MX2012005204A - Systems and methods for non-periodic pulse partial melt film processing. - Google Patents

Abstract

In one aspect the present description refers to a method for processing a thin film that includes, while advancing a thin film in a selected first direction, radiate a first region of the thin film with a first laser pulse and a second laser pulse. , each laser pulse provides a beam formed and having a creep that is sufficient to partially melt the thin film and the first region is re-solidified and crystallized, and radiate a second region of the thin film with a third laser pulse and a fourth laser pulse, each pulse provides a formed beam and has a creep that is sufficient to partially melt the region film, and the second region re-solidifies and crystallizes to form a second crystallized region, where the time interval and the second laser pulse It is less than half the time interval between the first laser pulse and the third laser pulse.

Description

SYSTEMS AND METHODS FOR THE PROCESSING OF FILMS BY PARTIAL FUSION THROUGH PULSES NO NEWSPAPERS Cross reference to related requests This application claims the priority of the North American application 61/264082 entitled "Systems and methods for the laser annealing of advanced excimeros" presented on November 24, 2009; 61/286643 entitled "Systems and methods for advanced excimer laser annealing," filed December 15, 2009; 61/291488 entitled "Systems and methods for advanced excimer laser annealing" filed December 31, 2009; 61/257657 entitled "Method for obtaining uniform films of polycrystalline silicon with small grain size with low density of defects between grains by crystallization with partial melting" presented on November 3, 2009; 61/257650 entitled "Method for obtaining uniform films of polycrystalline silicon with small grain size with low density of defects between grains by crystallization with partial melting", presented on November 3, 2009; 61 / 291,663 entitled "Advanced SLS with a single scan" filed on December 31, 2009; 61 / 294,288 entitled "Sequential Trip SLS" filed on January 12, 2010; 12/776756 entitled "Systems and methods for lateral solidification with sequential non-periodic pulse" filed on May 10, 2010 and international patent application PCT US2010 / PCT / 033565 entitled "Systems and methods for lateral solidification with non-periodic pulse sequential "submitted on May 4, 2010, the totality of each of the descriptions and are incorporated by reference in this document.

All patents, patent applications, patent publications and publications cited herein are explicitly incorporated by reference in their entirety. In the case of a conflict between the teachings of the application and the teachings of the incorporated document, the teachings of the application will prevail.

Field of the Invention The invention relates to a method for processing a thin film including, radiating a first region of the thin film with a first laser pulse and a second laser pulse, while advancing a thin film in a first selected direction, each laser pulse provides a formed ray and has a fluence that is sufficient to partially melt the thin film and the first region re-solidifies and crystallizes, and radiate a second region of the thin film with a third laser pulse and a fourth laser pulse, each pulse provides a formed beam and has a fluence that is sufficient to partially melt the J region film, and the second region re-solidifies and crystallizes to form a second crystallized region, in which the time interval and the second laser pulse is less than half the time interval between the first laser pulse and the third laser pulse .

Background of the Invention In the field of semiconductor processing, a number of techniques have been described for converting amorphous silicon thin films into p-or i-critical films. One such technique is the annealing of excimer lasers ("ELA"). ELA is a pulsed laser crystallization process that can produce polyethylene films with uniform crystal grains on substrates, such as, but not limited to, substrates that are heat intolerant (eg, glass and plastic) . Examples of ELA processes and systems are described in U.S. Patent Publication No. 20090309104, entitled "Systems and methods for creating polysilicon films controlled by crystallographic orientation" presented August 20, 2009; 20100065853, entitled "Process and Systems for the Processing of Laser Crystallization of Film Regions on a substrate using a linear type ray and structures of those film regions"; presented on March 9, 2006.

Conventional ELA tools use a single linear beam that continually scans at a low speed the surface of a sample with large overlap between pulses (eg, 95%) to establish a large number of pulses per unit area in a single scan. Thus, in ELA, a region of the film is radiated by an excimer laser to partially melt the film, which is subsequently crystallized. The repetitive partial melting of the film can lead to the formation of small grain polycrystalline films; however, the method frequently suffers from microstructural disuniformities, which can be caused by pulse-to-pulse energy fluctuations and non-uniform beam intensity profiles. Not only is a large number of pulses required to induce the cumulative effects that lead to a larger uniform grain size, but also to mitigate the effects of the edges of the short axis beam. In the beam edge segments of the beam, the energy is gradually reduced to zero. Depending on the location in the film, location-dependent variations may occur in the initial pulse energy sequence. This variation is not easily eliminated by the subsequent ELA process and can cause pixel brightness artifacts (ie, mura). Figure 1A illustrates a random microstructure that can be obtained with ELA. The Si film is irradiated several times to create the random polycrystalline film with a uniform grain size. Figure 1B represents a single conventional ELA scan, showing the cross section of the linear ray 101 on its short axis as beam 101 analyzes a film 104. Ray 101 advances in the direction of the arrow 102 and a region 103 of the film 104 can be radiated with multiple laser pulses as the ray 101 moves through the film 104.

Additionally, additional crystallization methods and tools have been reported that can be used to obtain a very high performance uniform grain structure ("UGS"). For example, a system of this type is described in the publication of the North American application no. 20070010104 entitled "Processes and systems for laser crystallization processing of film regions on a substrate using a line type ray and the structures of those film regions". UGS is a single pulse radiation process that may involve complete fusion crystallization ("CMC") or partial fusion crystallization ("PMC") of the film that is crystallizing. An additional feature of the UGS process is position control by firing laser pulses so that partial or complete fusion occurs only in those regions where the columns and rows of thin-film pixel ("TFT") transistors reside. When the separation distance between pulses exceeds the width of the linear ray, the radiated regions of the film (for example, amorphous Yes as deposited) remain between said columns. This selective area crystallization process ("SAC") can thus have very high performance since the average number of pulses per unit area could be less than one.

However, none of the above tools are especially well optimized for ELA for very large films, for example like those used in TVs that have a low pixel density. Conventional ELA is an inefficient process for these substrates, because time and resources are wasted when the substrate crystallizes between the pixel locations. While the UGS tools allow omitting these areas, the material obtained is significantly more defective than the typical ELA material and also the uniformity of the material may not be sufficient when typical radiation conditions are used.

Brief Description of the Invention A method and a non-periodic pulse tool are described by the sequential activation of the controlled position of lasers. The system can be implemented by several lasers to create distinct non-periodic laser pulses in the crystallization process, that is, different in that the results of each laser pulse is a cycle of fusion and independent partial solidification. Multiple lasers are used in a coordinated pulse sequence to radiate and crystallize selected areas of a film in a single scan or in multiple scans.

In one aspect, the present disclosure relates to a method of processing a thin film including, radiating a first region of the thin film with a first laser pulse and a second laser pulse, each laser pulse providing a beam formed and having a fluence that is sufficient to partially melt the thin film while advancing a thin film in a first selected direction, and for the first region to re-solidify and crystallize to form a first crystallized region, radiate a second region of the thin film with a third laser pulse and a fourth laser pulse, each pulse provides a formed beam and has a fluence that is sufficient to partially melt the thin film and the second region re-solidifies and crystallizes to form a second crystallized region , in which the time interval between the first laser pulse and the second laser pulse is less than tad of the time interval between the first laser pulse and the third laser pulse.

In some embodiments, the time interval between the first laser pulse and the second laser pulse is longer than a time interval for a melting and solidification cycle of the thin film. In some embodiments, each of the first laser pulse and the second laser pulse have the same energy density, each of the first laser pulse and the second laser pulse having a different energy density, each of the first pulse of the laser. laser and the second laser pulse reaches the same degree of fusion of the thin layer and each of the first laser pulse and the second laser pulse reaches a different degree of fusion of the thin layer. In some embodiments, the thin layer may be an amorphous silicon film lacking pre-existing crystallites. In some embodiments, the first laser pulse has a sufficient energy density to melt the amorphous silicon film and produce crystal structures with defective core regions. In some embodiments, the second laser pulse has a sufficient energy density to remelter the defective core regions to produce a uniform fine crystalline film.

In some embodiments, the thin layer may be an amorphous silicon film. In some embodiments, the thin layer is deposited by one of chemical vapor deposition of low pressure, chemical vapor deposition enhanced with plasma, crackling and electron beam evaporation.

In some embodiments, the thin layer may be a processed silicon film. In some embodiments, the processed silicon film is an amorphous silicon film lacking pre-existing crystallites which has subsequently been processed according to a method including advancing the amorphous silicon film in a selected second direction, radiating the amorphous silicon film with an extended laser pulse with sufficient fluence to partially melt the amorphous silicon film.

In some embodiments, the extended laser pulse is created by sequential accumulation of laser pulses from a plurality of laser sources in which the delay between pulses is sufficiently short to induce a single melt and solidification cycle. In some embodiments, the amorphous silicon film is obtained through chemical vapor deposition enhanced with plasma. In some embodiments, the extended laser pulse may have a pulse length greater than the full average width of 300 ns.

In some embodiments, the processed silicon film is a silicon film that is processed according to a method including advancing the silicon film in a second selected direction, radiating the silicon film with a laser pulse with sufficient fluence to completely melt the silicon film. In some embodiments, the laser pulse is created by the superposition of laser pulses from a plurality of laser sources.

In some embodiments, the method includes advancing the thin film in a selected second direction, radiating a third region of the thin film with a fifth laser pulse and a sixth laser pulse, each laser pulse providing a beam formed and having a fluence that is sufficient to partially melt the thin film and the third region re-solidifies and crystallizes to form a third crystallized region and radiate a fourth region of the thin film with a seventh laser pulse and an eighth laser pulse, each pulse provides a formed ray and has a fluence that is sufficient to partially melt the thin film and the fourth region re-solidifies and crystallizes to form a fourth crystallized region, in which the time interval between the fifth laser pulse and the sixth pulse Laser is less than half the time interval between the fifth laser pulse and the seventh laser pulse. In some embodiments, the second selected address is opposite to the first selected address and in the third region the second region is superimposed and the fourth overlaps the first region.

In some embodiments, the second selected address is the same as the first selected address and the third region overlaps the first region and the fourth region overlaps the second region. In some embodiments, the method includes moving the thin film in a direction perpendicular to the first selected direction prior to advancing the thin film in the second selected direction. In some modalities, every 1 I Laser pulse can be a beam in line with an upper part that has a uniform energy density. In some embodiments, each laser pulse may be a pulse of flood radiation.

Another aspect of the present disclosure relates to a thin film processed according to the above method. Another aspect of the present disclosure relates to a device with a thin film processed according to the above method, wherein the device includes a plurality of electronic circuits placed within a plurality of thin film crystallized regions. In some embodiments, the device can be a display device.

In one aspect, the present disclosure relates to a system for processing a thin film using non-periodic laser pulses including primary and secondary laser sources to generate laser pulses; a work surface for securing a thin film on a substrate; a platform for moving the thin layer with respect to the pulses of the beam and creating a direction of propagation of the laser beam pulses on the surface of the thin layer; and a computer for processing instructions for the synchronized pulsed laser phase to provide a first region of a thin film loaded on the mobile platform to be radiated by a first laser pulse from the primary source, a second region of the thin film to be radiated by a second laser pulse from the secondary source and a third region of the thin film to be radiated by a third laser pulse from the primary source, wherein processing instructions are provided to move the film relative to the lightning pulses in the direction propagation to radiate the first and second and third regions, in which the distance between the center of the first region and the center of the second region is less than half the distance between the center of the first region and the center of the third region, and in which the first, second and third laser pulses have a sufficient fluence to go partially thin layer. In some modalities, the stage moves at a constant speed.

Another aspect of the present disclosure relates to a method for converting an amorphous silicon film lacking pre-existing crystallites into a small grain film., the method includes advancing the amorphous silicon film in a selected first direction, radiating the amorphous silicon film with an extended laser pulse having sufficient fluence to partially melt the amorphous silicon film, where the small film grain It can have grains with average side dimensions smaller than the thickness of the film. In some embodiments, the extended laser pulse may have a pulse length of more than maximum full width of 300 ns and is a pulse of flood radiation. In some embodiments, the extended laser pulse is created by delayed accumulation of laser pulses from a multitude of laser sources in the delay between pulses is short enough to induce a unique fusion and solidification cycle. In some embodiments, the amorphous silicon film is obtained through chemical vapor deposition enhanced with plasma.

Another aspect of the present disclosure relates to a method for processing a thin film, including the application of a thin semiconductor film on a substrate, the thin layer having a bottom interface located on a lower surface adjacent to the substrate and an upper surface facing to the lower surface; and radiate the thin layer with a laser beam with an energy density greater than 1.3 times the full melting threshold of the film, the energy density is selected to completely melt the film; and wherein at the beginning of solidification a PAC layer is present to form a surface interface on the upper surface of the semiconductor film; where after irradiation and complete melting of the film a heterogeneous nucleation occurs in both the upper and lower interface and in which upon cooling the heterogeneous nucleation forms silicon grains with few defects in the lower surface of the film. In some embodiments, the laser beam has a pulse duration greater than 80 ns or from 200 ns to 400 ns. In some embodiments, the thin semiconductor film includes a silicon film having from about 100 nm to about 300 nm in thickness. In some embodiments, the substrate may be glass or quartz. In some modalities, the grains may be small grains. In some embodiments, the energy density of the laser beam is 1.4 times the local full melting threshold. In some embodiments, the PAC layer is formed by depositing a thin layer on the upper surface of the thin layer before radiation. In some embodiments, the boundary layer may be an oxide layer with a thickness of less than 50 nm. In some embodiments, the PAC layer is formed by radiating the thin layer in an oxygenated environment. In some embodiments, the oxygenated medium may be air. In some embodiments, the oxygenated medium may be oxygen only. In some embodiments, the substrate may be a stamped metallic film covered by an insulating film and in which the energy density is greater than 1.3 times the full melting threshold of the thin film. In one aspect the description refers to a lower gate TFT made in accordance with the above method, where the metallic interlayer film can be a gate of the lower part and the insulating film can be a gate dielectric.

The system and the non-periodic method present high performance ELA and selective area crystallization. Such a process is desirable for TV of active organic matrix ("AMOLED") ray emitting diodes and ultra-high definition liquid crystal ("UD-LCD"). For these two products, amorphous silicon lacks performance and stability, while low-performance low-temperature polysilicon ("LTPS") technology is not seen as cost-competitive in the required group sizes (eg, Gen8, up to 2.2x2.5m2).

Brief Description of the Figures The following description will be easier to understand with references to the following drawings in which: Figure 1A illustrates a random microstructure obtainable with ELA; Figure 1B represents a conventional single scan THE A; Figures 2A-2C depict exemplary energy profiles of laser pulses according to one embodiment of the present disclosure; Figure 2D represents an amorphous silicon film of chemical vapor deposition enhanced plasma radiated in a single shot (PECVD); Figure 3A represents a non-periodic pulse ELA system, according to one embodiment of the present disclosure; Figure 3B represents a sample used in the ELA system of non-periodic pulses, according to an embodiment of the present disclosure; Figure 4 shows an exemplary profile of the beam pulse, according to one embodiment of the present disclosure; Figure 5A depicts an ELA process of non-periodic pulses, according to one embodiment of the present disclosure; Figure 5B is an exploded view of the region 590 of Figure 5A according to one embodiment of the present disclosure; Figure 6 represents an ELA process of non-periodic pulses, according to an embodiment of the present description; Figure 7 shows a first scanning non-periodic pulses as described in Figure 5A and also includes a second scan in the reverse direction of the film, according to one embodiment of the present disclosure; Figure 8A describes the crystallographic structure of a film after radiation, according to an embodiment of the present disclosure; Figure 8B is an illustration of the crystal structure in Figure 9A, according to one embodiment of the present disclosure; Figure 8C shows an atomic force microscope ("AFM") scan of the surface of a film after radiation at a higher energy density but still in the PMC regime, according to one embodiment of the present disclosure; Figure 8 is an illustration of the crystal structure in Figure 8 according to one embodiment of the present disclosure; Figure 8E shows a circular region that formed after lateral crystallization of an unfused seed, according to an embodiment of the present disclosure; Figure 9 represents a response function of the thin film interface, according to one embodiment of the present disclosure; Figure 10A depicts FTR and BTR for an amorphous Si substrate on a 150 nm glass with an oxide layer of 300 nm in vacuum, according to one embodiment of the present disclosure; Figure 10B is similar to 10A except that 10B shows empty results, according to one embodiment of the present disclosure; Figure 11A shows a nanosecond time plot (x axis) versus normalized reflectance values (y axis) for an Si film of nm 200 with 300 nm of an air layer surface in air at 1.32 CMT and in vacuum at 1.4 CMT, according to one embodiment of the present description; Figure 11 B is an image of the microstructure obtained in the air environment.

Figure 11C is an image of the microstructure in the vacuum environment.

Detailed description of the invention The present disclosure relates to systems and methods for utilizing periodic laser pulse techniques in combination with partial melting crystallization and full melting crystallization techniques for polycrystalline films in a uniform manner. In some embodiments, ELA of non-periodic pulses is used to produce uniform fine-grain crystalline films of Si Amorgo films as deposited lacking pre-existing crystallites, for example films obtained by chemical vapor deposition of low pressure (LPCVD), deposition improved vapor chemistry with plasma (PECVD), crackling or electron beam evaporation. In some embodiments, a flood radiation method or producing a fine grain uniform crystalline film or to produce a precursor film of a non-periodic pulsed radiation method may be used. The flood radiation method can be the partial fusion process of two shots in which an amorphous silicon film devoid of any pre-existing crystallites (eg, a PECVD film) is transformed into two steps in a fine grain uniform crystalline film with grains having average lateral dimensions that exceed the thickness of the film, ie, small columnar grains. The flood radiation method can also be a partial fusion process of a single shot of extended duration in which an amorphous silicon film lacking any pre-existing grain (eg, a PECVD film) is transformed into a uniform crystalline film of fine grain with grains with average side dimensions less than the thickness of the film. The flood radiation method can also be a complete fusion process in which an amorphous silicon film of any kind with oxide interfaces at the top and bottom of the film is transformed into a small equiaxed grain Si film. with few defects.

An ELA tool and method of non-periodic pulses is described by sequential activation of laser controlled position. The system can be implemented by several lasers to create distinct non-periodic laser pulses in the crystallization process, for example, different in that the results of each laser pulse in a non-periodic and non-periodic partial solidification and fusion cycle in which the intervals between pulses are not the same. Multiple lasers are used in a coordinated pulse sequence to radiate and crystallize selected areas of a film in a single scan or in several scans. Several scans may be convenient to reach a greater number of melting and solidification cycles in regions of interest in order to benefit from the cumulative effects of multiple radiations observed in ELA leading to more uniform polycrystalline films, eg, greater distribution of grain size.

Pulse not newspapers Exemplary sequences of laser pulses are shown in Figures 2A-2C. The y-axis represents the density of energy and the x-axis represents time. Figure 2A shows a periodic laser pulse that can be used for a conventional ELA process. The periodic laser repetition rate results in a laser pulse pattern that is uniformly in the time domain. Figure 2B represents an example of the non-periodic pulse described here where a second pulse 105 is triggered in a time relationship very close to the first pulse 106. Then, a third pulse 107 is triggered in the time interval different than the interval between first pulse 106 and second pulse 105. Figure 2C illustrates an embodiment so that both the pulse and the laser power (energy density) of the laser pulses are different. Thus, the radiated film experiences a variable radiation energy and non-periodic pulse rate. Due to the relatively short time between the first pulse 106 and the second pulse 105, the regions radiated by the first pulse 106 and the second pulse 105 experience a greater overlap.

The time delay between the first pulse 106 and the second pulse 105 may be less than half the time interval between the first pulse 106 and the third pulse 107. In some embodiments, the time interval between the first pulse 106 and the second pulse 105 is less than one tenth or less of twentieth one or less one hundredth the time interval between first pulse 106 and third pulse 107. The time delay between first pulse 106 and second pulse 105 may be about three microns at about one millisecond, about five microseconds at about 500 microseconds and about 10 microseconds at about 100 microseconds.

Thus, Figure 2B and 2C present a non-periodic pulse pattern employing two closely spaced or a "train" of two laser pulses; However, a greater number of spaced pulses may be employed, for example, 3-5 or more, corresponding to three to five or more lasers or laser cavities. In such embodiments, where a greater number of closely spaced pulses of different lasers, for example, lasers are used from two different laser energy sources or two different laser carriers from the same laser energy source, the target region a p rop ore ion number is radiated more often. For example, n pulses from n laser sources can be closely spaced to form a train of n laser pulses and a single region will experience n radiations in a single scan. The beam can have similar widths as in the conventional ELA process.

The two consecutive pulses in a pulse train do not need to have the same energy density. For example, if the film is still hot from the first pulse, the second pulse could have a lower energy density than the first pulse. Also, a higher energy density can be used to compensate for changes in the optical properties in the first pulse (amorphous silicon that absorbs UV rays a little better than crystalline silicon). Suitable options for the energy density of the second pulse may take into account effects and possibly other aspects as well., in such a way that the film experiences the same degree of fusion. Here, the degree of fusion is understood as a melting measure independently of the details of the fusion, which can vary considerably depending on the precursor phase (amorphous or crystalline), heterogeneity (eg, uniformly defective or having defective nuclei surrounded by larger and cleaner grains) and the surface morphology (smooth or rough, for example, has periodicity similar to the wavelength of light). The same degree of fusion is achieved when the melting point during the second pulse is equivalent to that of the first pulse, for example approximately! 80% of the movie. In a multi-scan process that aims to benefit from the cumulative effects that lead to more uniform polycrystalline films it is desired that most pulses result in the same degree of fusion for the process to be more efficient.

Thus, as shown in Figure 2, the first laser pulse and the second laser pulse may have different energy densities. Specifically, Figure 2 represents the first laser pulse with a lower energy density than the second pulse. However, in some embodiments, the second laser pulse has a lower energy density than the first laser pulse. In addition, in a multiple scanning process, the deviation between the energy densities of the first pulse and the second pulse may be different or absent in different scans. For example, the displacement of the energy density between the first and second pulses in a first scan can be selected to compensate for a change in the optical sensing properties, while a second scan, the displacement can be selected to compensate for the temperature. In some embodiments, although the two pulses may have different energy densities, a second lower energy pulse may cause the same amount of fusion in the film as a first pulse of higher energy due to the residual heat in the film from the first pulse.

In one embodiment, the present system creates non-periodic laser pulses using coordinated pulsing of a plurality of laser sources (as is also possible using a single laser source that only has multiple laser cavities, eg, tubes) to produce a series of closely spaced pulses in the time domain. A plurality of laser sources can be incorporated into a single laser system. A laser system is a computer-controlled system that uses computer-controlled techniques to radiate a substrate by default, for example, the equipment controls the firing of the lasers and the day-moving movement and one or more laser cavities to produce one or more of the laser beams. Each laser beam corresponds to a laser source. Each laser beam can be produced from a stand-alone laser or a laser cavity that is part of a plurality of laser cavities contained within a laser system.

Tools that have multiple laser cavities, for example, tubes, have been previously described (1) increase the pulse energy per shot simultaneously and subsequently combine several pulses and (2) increase the pulse duration by delaying the firing of several tubes and subsequently combining them, as described in U.S. Pat. no. No. 7,364,952, entitled "Thin Film Processing Systems and Systems," issued April 29, 2008. In other words, the pulses are combined to offer a single modified melting and solidification cycle. The non-periodic ELA pulse is different since it uses the laser pulses of several separate melting and solidification cycles. However, the pulses are close enough in the time domain that they demonstrate a significant overlap, while the stage is traveling at high speed.

In addition, the non-periodic pulse tool and method ELA can also be used to perform the selective crystallization of areas of a film in order to crystallize only those areas of the film that will be formed as electronic components. The tool and method of non-periodic pulses provide selective crystallization in areas resulting in crystal growth in a first region of the film, followed by a break determined by the repetition rate of the lasers and then considerable overlap in the second pulses of two or more lasers resulting in the growth of the crystal in a second region of the film. The time between laser pulses gives rise to non-periodic laser pulse sequences and substantial overlap in radiated regions, which is explained in detail below. Such methods and systems can be used for ELA processes with high performance.

In in the selective crystallization of area, the film crystallizes in places where electronic devices are made (in a later process not discussed here). However, not all electronic devices need an equally uniform or even equally conductive material. For example, small TFTs can be much more demanding in terms of crystal uniformity than large TFTs or even large capacitors. Likewise, TFTs that are used for current driving may require better TFT uniformity used to change. Therefore, from a total area of a certain region to be crystallized, only a fraction must be crystallized with a high number of laser pulses to obtain a region of great crystal uniformity and conductivity, while the rest can be processed with fewer pulses or even a single pulse. The non-periodic pulse of selective area crystallization ELA provides a framework to scan only selected areas of a film, reducing processing time.

Non-periodic pulses ELA A non-periodic ALS system includes one or more of the following features: multiple lasers or laser tubes and means for delayed triggering of subsequent pulses to have a succession of brief pulses. The system may also include tripping the controlled position pulses so that the laser beam pulses radiate a specific position on the substrate. The timing of the two closely spaced pulses in time should be such that the radiated portion of the film is allowed to solidify between pulses, while the position control ensures that the radiated region is correctly on the substrate, for example, to create a column of TFT pixels or circuits. It is also desirable that the laser beam pulse has an upper beam profile with a beam width that is sufficient has the pulse sequence overlap in a selected region.

The number of laser sources can be chosen based on various considerations such as performance, laser power, panel size, screen size, system design and tool maintenance. A greater number of lasers will generally result in higher crystallization rates, but will also require a greater number of optical elements, which can result in more complicated and costly system design. Also, a greater number of lasers can cause a greater downtime of the tool due to the need for more frequent service, for example tube replacement. Exemplary values for the number of lasers can be two to four or more lasers each with a power of approximately 600 W or more to process glass panels that can be larger than two meters2 and possibly as large as five or 7.5 m2 for displays diameters as large as 30, 40, or 50 inches or more.

Non-periodic pulse ELA tools can offer the following benefits over conventional ELA and UGS tools: 1. Efficient power supply to preselected regions: under position control, intermediate pixels of TFTs / circuits regions do not crystallize unnecessarily. This leads to higher rates of effective crystallization. 2. Elimination of artifacts related to the edge of lightning: the edges of lightning do not affect the regions TFT / pixel circuit so that the crystallized regions all experience the same exact pulse sequence. 3. Optimization of the pulse sequence: the regions are radiated by a sequence of pulses from multiple laser sources and during a multitude of scans and as such the sequence can be optimized (for example, pulse energy, pulse duration, pulse preheating) ). 4. Mitigation of beam un-uniformities in the long axis by applying a perpendicular displacement between scanning (the de-uniformities in the short axis can also be mitigated with an effective parallel displacement within or between scans, that is, by changing the lateral position of the beam with respect to the regions of interest).

Multiple scans are normally required for ELA in non-periodic pulses to obtain satisfactory material uniformity. The operation of ALS SAC pulses of non-periodic pulses typically yields higher yields than conventional ALS. In addition, the number of pulses with the ALS of non-periodic pulses needed to obtain an acceptably uniform crystal structure may be less than that required with conventional ELA. In conventional ELA, the edges of the beam overlap in the area of interest resulting in variation in the crystal structures of the radiated region along the direction of the scan. The variation in the crystal structure was for example described by Im and Kim, Phase transformation mechanisms involved in the crystallization of excimer laser from amorphous silicon films, Appl. phys Lett. 63, (14), October 4, 1993, in which the variation in grain size as a function of energy density in partially melted low pressure steam chemical deposition films ("LPCVD") is discussed; Si amorfo LPCVD films are believed to contain small crystallites that trigger crystallization leading to films with a grain size that increases with energy density. In vapor-deposition chemistry films ("PECVD") enhanced with plasma, the melting and solidification processes are complicated by the absence of these grains. Thus, crystallization is preceded by the formation of crystals through a nucleation process. When the density of the nucleation is low, this can result in disc-shaped crystal structures, as for example visible at the end of a single shot, i.e., a pulse of a laser, radiated which is shown in the figure 2D in the film PECVD of Si amorfo. Figure 2D shows an edge region 120 of an amorphous Si film of a single shot PECVD. This edge region 120 has both a part of amorphous Si 122 and a part of crystalline Si 124. However, the transition region 126 between amorphous Si and crystalline Si is not a phylum, but a heterogeneous region containing a mixture of material crystalline and amorphous. The non-uniformity of the film after the first radiation is thus affected by the existence of grain size variation and crystal structures in the form of discs. These disuniformities can not easily be removed in later radiations. In conventional ELA, even after 10 pulses or more, the effect of the energy density gradient of the first ray pulse edge may be visible. Therefore, a large pulse number is necessary to erase the history of the first edge of the ray pulse.

As described herein, SAC using ELA of non-periodic pulses may require fewer pulses to achieve an equally uniformly crystallized film. As explained in more detail below, the energy profile on the short axis of a linear beam contains output edges that gradually change the energy density and a central planar region of relatively constant energy. The term "linear beam", as used herein, refers to a beam having a width substantially less than the length of the beam, i.e., the beam has a large proportion. In conventional ELA, the edges of the beam are an important source of disuniformity of the material. In non-periodic pulse ELA, the edges of the ray are located outside the region of interest so that the region of interest is radiated with the upper portion of a first pulse. In addition, the energy density of the beam can be optimized to create the most uniform starting material for the cumulative process to reduce the number of pulses required to achieve a desired level of material uniformity.

System to perform ELA of non-periodic pulses Figure 3 represents an ELA system of non-periodic pulses. The system includes a plurality of laser pulse sources 110, 110 'running for example at 308 nm (XeCI) or 248 nm or 351 nm. A series of mirrors 206, 208, 212 direct the laser beam to an example stage 180, which is capable of scanning in the y-direction. The beam is shaped as a linear beam with a length of for example about 360 mm, or about 470 mm, or about 720 mm or any suitable length for processing a glass panel into one, two or more scans. The system may also include a slit 140 which can be used to control the spatial profile of the laser beam and the energy density meter 216 for measuring the reflection of the slit 140. An optional obturator 228 can be used to block the beam when it is not present a sample or no radiation is desired. Sample 170 may be placed in step 180 for processing. In addition, homogenizers can be used to provide a more uniform upper beam profile. An attenuator can be used. The energy of the beam is controlled by controlling the laser directly. Step 180 may be a linear translation stage and may have the ability to make lateral translations. Optionally, the system may include a pulse extender 213 and a mirror 214 to create pulses of extended duration.

The translation step of the sample 180 is preferably controlled by a counting arrangement to effect translatations of the sample 170 in the planar direction, as well as, optionally, in the x direction and the z direction. In this way, the counting arrangement controls the relative position of the sample 170 with respect to the pulses of the radiation beam. The repetition and density of the energy of the pulses of the radiation beam are also controlled by the counting arrangement. Those specialized in the technique that instead of the ray source J J 110, 110 '(for example, excimer laser pulses), the pulse of the radiation beam can be generated by another known source of pulses of energy unsuitable to at least partially melt (and possibly melt fully its entire thickness) areas selected from the semiconductor thin film (e.g., silicon) of the sample 170 in the manner described below. Such known sources can be a pulse of solid-state lasers, an interrupted continuous-wave laser, a pulsed-electron beam and a pulsed-ion beam, etc. Normally, the radiation beam pulses generated by the sources of the beam 110 , 110 'provide a lightning intensity at the sample level in the range of 400 mJ / cm2, 1 J / cm2 or 1.5 or more, a pulse duration (FWHM) in the range of 10 to 300 nsec and a rate of pulse repetition in the range of 10 Hz-300 Hz at 600 Hz or 1.2 kHz or more.

The exemplary system of Figure 3 can be used to carry out the processing of the semiconductor thin film of the sample 170 in the manner described below in more detail. A mask / slit can be used in the exemplary system of the present disclosure to define the profile resulting in the masked beam pulse and the reduction of the non-uniformity of the adjacent portions and the edge regions of the semiconductor thin film portions. when these 3 A portions they are radiated by such pulses of lightning masked and then crystallized.

For example, a linear beam for the non-periodic pulse process ELA may have a width of about 100 or less than 300 microns to about 400 to 600 or more microns. The fluence of the ELA rays is selected so as not to induce complete melting of the film. Therefore, the ELA beam should have a fluence of less than about 5% to 30% or more of the creep value that induces complete melting in the given film. The yield value that induces complete melting depends on the thickness of the film and the duration of the pulse. In addition, ELA rays could have relatively low repetition rates of about 300 Hz to about 600 Hz. The described high power lasers provide sufficient energy per pulse to provide sufficient energy density throughout a radiated region so the pulse You can melt a movie within that region.

The linear beam of ELA can be created from a laser source of relatively low frequency, as used in certain systems available from JSW (The Japaese Steel Works, Ltd., located at Gate City Ohsaki-West Tower, 11-1, Osaki 1-chome, Shinagawa-ku, Tokyo, Japan). High frequency lasers, such as available in TCZ, are not well suited for the ELA process of non-periodic pulses as the required scanning speed, which is dictated by the pulse repetition rate and the separation of the TFT or circuits, is It gets very high As illustrated in Figure 3B, a thin semiconductor film 175 of the sample 170 can be placed directly on, for example, a glass substrate 172 and can be supplied in one or more intermediate layers 177 there. The semiconductive thin film 175 can have a thickness between 100 Angstrom and 10,000 Angstrom (1 miera) as long as at least certain necessary areas can be melted at least partially or totally along its thickness.

According to an exemplary embodiment of the present disclosure, the semiconductor thin film 175 may be composed of silicon, (eg, a thin film of amorphous silicon), germanium, silicon germanium (SiGe), etc., all of which preferably have low levels of impurities. It is also possible to use other semiconductor elements or materials for the semiconductor thin film 175. The intermediate layer 177, which is located immediately below the semiconductor thin film 175, may be composed of silicon oxide (S i O 2), silicon nitride. (Si3N "), and mixtures of oxide, nitride or other materials.

An exemplary profile of the beam pulse 200 is illustrated in FIG. 4, which can also be formed by the optical components of the system illustrated in Figure 3A or produced by a mask. In this exemplary embodiment, the energy density of the lightning pulse 200 has a profile 220 with an energy density that is below the full melting threshold, i.e., the energy density of the lightning pulse that completely melts the film. In particular, this profile 220 includes an upper portion 205, a forward portion 210 and an edge portion 215. The upper portion 205 of this embodiment extends for a width of C, within which the energy density is approximately constant. The width c can be between 100 microns to 1 mm. The front portion 210 may extend a distance D1 (e.g., between 50 and 100 microns), and the edge portion 215 can be extended a distance D2 (for example, also between 50 and 100 pm). The front potion 210 has a section with a length of D1P, which extends from the point when the energy density is approximately constant to a point below the crystallization threshold, ie the energy density of the lightning pulse that crystallizes the movie. Also, the edge potion 215 has a section with a length of D2P that extends from the crystallization threshold point, to a greater point when the energy density is approximately constant. The upper part 205 is commonly called the "upper" part of the beam.

The system may also include several projection lenses to activate the simultaneous scanning of several sections of a thin film. A system that allows simultaneous scanning of several sections of a thin film is described in U.S. Patent No. 7,364,952, entitled "System and method for processing thin films". Although the method and system have been described using a dual laser source, additional lasers can also be used.

The pattern of the non-periodic laser pulse is preferably obtained by the deflection shot of a plurality of lasers of the same repetition rate. As noted above, the lasers can be controlled by a computer system to produce the pulse energy profiles depicted in Figures 2B-2C. As mentioned above, in the described modalities, two laser tubes appear, more than two laser tubes can be used for ALS of non-periodic pulses. For example, three, four, five or more laser tubes, each laser pulses emitted independently can be used to provide up to three, four, five or more radiations in each part of the film during each scan.

The film 170 can be an amorphous or polycrystalline semiconductor film, for example a silicon film. The film can be a continuous movie or a discontinuous movie. For example, if the film is a discontinuous film, it can be a film with a lithographic pattern or a film deposited selectively. If the film is a selectively deposited film, it can be through chemical vapor deposition, sputtering, or a thin film processed in solution, for example ink jet printing of silicon based inks. ELA methods of non-periodic pulses Figure 5A depicts an ELA process of non-periodic pulses. Figure 5A shows an exemplary illustration of a film that has been radiated by two sets of two laser pulses, in which the first two laser pulses occur very close in time, followed by a delay (during which the substrate continues to advance in the direction - and as indicated by arrow 980), and the second two laser pulses also occur together in time. The process includes at least four radiation steps, with two radiation steps (steps 1 and 3) corresponding to the main laser pulses and two radiation steps (steps 2 and 4) corresponding to the secondary laser pulses.

Figure 5A illustrates sequential translates of the thin film 175 of the sample 170 with respect to the linear type ray pulses 164 formed by the optical components of the system of Figure 3A and / or patterned by a mask. Figure 5B is an exploded view of the region 590 in Figure 5A. In this exemplary illustration of the radiation of the semiconductor thin film 175 in the sample 170, the sample 170 moves in a negative direction (arrow 980) with respect to the direction of the linear type ray 164. When the sample 170 is moved in this way to a position such that the linear type ray 164 points towards a first row 510 of the thin film 175, the source of the beam 110 is driven by the counting arrangement so that a first linear type pulse of lightning 410 of a primary source of laser 110 radiates and at least partially melts, one or more portions 511-519 in the first row 510 of the semiconductor thin film 175. The profile and length of the first linear type pulse 410 is shown in figure 5 its sta nc i I n corresponds to the profile and length of the pulse 200 illustrated in FIG. 4. The width c of the top 205 of the first pulse 410 is preferable to be wide enough to radiate and partially fusing the cross sections of all portions 511-519 in region 910. These portions can be designed to place certain structures (eg, TFT) therein so they can be used to define the pixels. The re-solidified parts that are partially melted would probably have small grain regions, but include relatively uniform material. The melted portions 511-519 re-solidify and crystallize in such a way that they have a uniform crystal grain growth.

Second, a second pulse linear beam 410 of a secondary laser source 110 'radiates the thin layer 175 to induce partial melting of the thin layer 175. The hat portion of the second ray pulse line 410 radiates a second region 920 of the thin film 175 to partially melt the entire cross sections of portions 511-519. As shown in Figure 5, region 910 and 920 have significant overlap and form a first crystallized region 960. In the non-periodic pulse described ELA process, the overlap between the first region and the second region may be greater than 70%, higher 85%, more than 90%, more than 95% or more than 99%.

After the first row 510 is radiated and partially melted using linear type pulses 410 and 410 as described above, the sample 170 moves in the negative direction (through a control of the counting arrangement so that the lightning 164 collision in a second row 520 of the semiconductor thin film 175 in the sample 170. As for the first row 510 and upon reaching the second row 520, the primary laser source 110 is driven by a counting arrangement to generate a third linear type pulse 420 from the main laser radiating and at least partially or totally melting one or more sections 521 -529 in region 940 of the second row 520 in substantially the same way as described above with respect to the radiation of the first row 510. Next, a fourth linear pulse ray 420 of the laser secondary source 110 'radiates the thin layer 175 to induce partial melting of the thin layer 175 including or sections 521 -529. The upper portion of the fourth linear beam pulse 420 radiates a fourth region 950 of the thin film 175. As shown in Figure 5, the third region 940 and the fourth region 950 have a significant overlap to form a second crystallized region 970. In the non-periodically described ELA process, the overlap between the first and the second region may be greater than 70%, greater than 85%, greater than 90%, greater than 95% or greater than 99%.

This translation of the sample 170 (whereby the incidence of the linear type ray 164 is shifted from the first row 510 to the second row 520 of the semiconductor thin film 175) is executed a distance D. The distance D may also refer to a periodicity of the rows of pixels or separation of the pixels because the translation of the sample 170 through the distance D is performed for other rows of the sample 170.

The translation of the sample 170 with respect to the incidence of the beam 164 can be performed continuously (for example, non-stop). The computing arrangement can control the lasers 110, 110 'to generate the corresponding pulses 410, 410', 420 420 'based on a predefined frequency. In this way, it is possible to define the translation speed V of the sample 170 with respect to the incision in the semiconductor thin film 175 of the linear type pulses 410 ', 410, 420', 420 in such a way that the respective rows 510 , 520 of the thin film 175 are accurately radiated by the pulses. For example, this velocity V of the translation of the sample 170 can be defined as follows: V = Dxf | aser where i a r is the frequency of each of the lasers. Therefore, if the distance D is 200pm and the fiaSer is 300 Hz, the speed V can be approximately 6 cm / sec, which can be a constant speed.

While the sample 170 does not have to be continuously moved with respect to the incidence of the beam 164, the operation of a main laser source 110 and a secondary laser source 110 'can be controlled on the basis of a positional signal provided by the step of translation 180. This signal can indicate the position of the sample 170 relative to the position of the incidence of the linear type ray 164. Based on the data associated with that signal, the counting arrangement can direct the performance of the laser sources 110 , 110 'and the translation to the sample 170 to achieve effective radiation of specific parts (e.g., rows) of the semiconductor thin film 170. Therefore, the location of controlled radiation of at least parts of the semiconductor thin film 175 it can be achieved by means of a ray of linear type 164.

All four radiations partially fuse the region and the molten region then rapidly solidifies to form a crystallized region. The area of the thin layer 175 where the first region 910 and the second region 920 overlap constitutes the first crystallized region 960. The area of the thin layer 175 where the third region 940 and the fourth region 950 overlap constitutes the second crystallized region 970 The speed of the film and the repetition rate (frequency) of the first and second laser pulses determine the location of the posterior crystallized regions on the film. In one or more embodiments, the first and second crystallized regions 960 and 970 may also overlap, as the film is scanned in the direction y, the surface of the entire film may be crystallized.

As shown in Figure 5A, the first and second crystallized regions 960 and 970 do not overlap. Therefore, the non-periodic pulse sequence can be used to selectively crystallize only certain regions of interest, e.g., TFT or pixel circuits 511-519 and TFT or circuits 521 -529 in an active array device, such as a screen or a sensor arrangement. In this SAC mode, there is no overlap between the first and second crystallized regions 960 and 970. Due to the lack of superposition, the stages in which the sample is made can move at a higher speed to increase the space between the crystallized regions. and second 960 and 970 to match the periodicity of matrix type electronic players. That increase in phase velocity can result in a significant increase in overall processing performance. For example, in the pixel matrix of a screen, the density of the electronic players is quite low, for example, it has a pixel pitch of several hundred μ? or more, for example, more than 1 mm or more, a considerable increase in performance can be achieved only by crystallizing those regions. Consequently, the stage can be moved at faster speeds for a laser pulse given full crystallization of the selected areas in the film. Exemplary performance values for an ELA system of non-periodic pulses are referred to in the examples section of this application. Therefore, the improvement to the performance of the non-periodic pulses of the SAC allows more competitive performances for large panels, for example, panels of Gen8 (-2.20 x 2.50 m2), as is necessary for the manufacture of large televisions.

Figure 6 represents a scan similar to the scan shown in Figure 5A, except that the first and third pulses of linear rays 1000, 1010 have a lower energy density than the second and fourth linear beam pulses 1020 and 1030. Figure corresponds to the energy densities represented in Figure 7C. The energy densities may range from about 20% to about 70% of the completed melting threshold. Generally, in the non-periodic ELA pulse, the first melting and solidification cycle can be optimized to provide the most uniform crystal structure to benefit the cumulative process in ELA resulting in material with sufficient uniformity with low defect density. For example, the first pulse may have an energy density greater than the complete fusion threshold. This higher energy density, for example, could easily be achieved by simultaneous firing of the first two pulses to result in only one melting and solidification cycle (that is, they are not different). Similarly, the first two pulses can be triggered with a small delay to form a combined pulse that has a longer pulse duration that can benefit from the uniformity of partially molten material even more, particularly when the starting material is PECVD deposited on a film. of Yes.

Figure 7 represents a first non-periodic pulse scan as described in Figure 5A and also includes a second scan in the reverse direction of the film 1100. In the first scan of Figure 7, five regions 1110, 1112, 1114, 1116 and 1118 are radiated as the scan continues in a first direction 1120. As we have discussed with respect to Figure 5A, each of the five regions 1110, 1112, 1114, 1116 and 1118 correspond to a region radiated by a first pulse. of linear beam 1122 and an area radiated by a second linear beam pulse 1124. Each radiation produces the partial melting and subsequent crystallization of the radiated region. The superposed region formed by the region radiated by a first linear beam pulse 1122 and the region radiated by the second linear beam pulse 1124 corresponds to the first region 1110. After all five regions of the film have been radiated in a first scanning, the film travels in the positive x-direction and a second scan occurs in the opposite direction to the first scan, in the direction of arrow 1130. A conventional multi-scan ELA technique is described in 2010 WO / 056990 entitled "Systems and methods for the crystallization of thin films". In some embodiments, the film does not move in the x direction before scanning or the film may be shifted in the negative x direction between the first and second scans. The second scan, as shown in FIG. 7, results in radiated regions 1132, 1134 and 1136, etc. This multi-pass scan can provide a higher quality crystallographic film. The movie can be scanned one, two, three, four, five or more times.

Therefore, the ELA system of non-periodic pulses may be able to execute multiple scans to arrive at a number of pulses that are desired, for example, a four-laser tube system can be used in a process of five scans to reach a total of 20 pulses per unit area of the film. The technique allows an exact control of the pulse energy sequence for each segment of the film. For example, in ELA non-periodic pulses, it may be the first pulse in each train of pulses during the first scan with less fluence than subsequent scans. In some embodiments, the last pulses to affect the surface may have a low energy density to induce surface melting in order to reduce the roughness of the surface of the films processed by ELA. In addition, each segment of the TFT of pixels or circuits or any part of it can have the exact same pulse energy density sequence so beam radiation can be completely avoided. The avoidance of beam edges to affect the areas of interest means that the cumulative process can more rapidly converge to a material with desirable uniformity and as such, the total number of pulses of such material can be reduced compared to the conventional ELA process. Therefore, the benefits of the method are two: reduction of the average number of pulses as a result of the selective crystallization of area and the number of pulses in areas of interest due to the initial reduced non-uniformity of the material and after the first pulse as result of avoiding radiation with the edges of the beam.

Compared with the previously discussed ELA methods, the lightning width in the selective area crystallization of non-periodic ALS pulses can often be smaller; it just needs to be as wide as the width of the regions that crystallized. Therefore, there are surplus energy that can be used to increase the length of the beam. A beam length can be made using larger projection lenses. In addition, the beam can be divided into different optical viewing paths to simultaneously crystallize several regions in the film during digitalization of the lightning pulses. By increasing the length of the region transformed into a scan, the total number of scans needed to fully crystallize the film can be reduced.

In addition, ELA periodic pulse-selective area crystallization can be used to precisely align the upper portion of the beam that the region of interest is not radiated by the posterior edges of the beam. Ideally, the first radiation of the area of interest should be with the upper portion of the beam or at least be a portion of the linear beam having a similar energy density above the crystallization threshold of the film. In this way, selectively radiate the film in such a way that the ray edges do not radiate the region of interest in the film, the number of scans necessary to create the required microstructure and uniformity within the film can be reduced.

In some embodiments, optical components can be used to divide the rays into two or more linear rays that are each directed to another TFT column of pixels or pixel circuits (or at least, places where they will later be manufactured TFT or pixel circuits). In this way, using a ray divided into two linear rays, twice the number of pulses per unit area can be obtained so that even less scanning is necessary to reach full crystallization. The multitude of parallel line beams can be used to impinge on adjacent columns of TFT / pixel circuits or can be used to impinge on non-adjacent columns. The multitude of line rays can be generated by the known ways of dividing rays and orienting them in separate optical tracks. The split rays can also be assembled to jointly travel part of the optical path, for example through the projection lenses or even immediately after the separation. The split rays can travel parallel to each other and at an angle slightly offset from each other. Dividing the rays while maintaining the beam length would result in rays that are approximately 1 μm wide, where m is the number of linear rays.

The concrete parameters of the ELA method of non-periodic pulses depend on the width of the beam, which in turn may depend on the width of the region to be crystallized. For example, the size of the active matrix device may suggest certain dimensions in pixels. Pixel dimensions can result in new pixel designs that take advantage of the non-periodic ELA processing capabilities. For example, a 55-inch screen with a pixel pitch of 660 prn may require crystallized regions as wide as 300 pM. Greater contraction of the dimensions in pixels (for example for high definition screens) and the optimization of the design towards a more suitable distribution with non-periodic ALS crystallization schemes, can reduce the dimension of this region for example below 150 pm. The optimization can also include different pixel designs in two adjacent columns: TFT / circuits in the adjacent columns can be placed close together so that they can be superimposed within a single radiation, after the distance traveled in a region close to to be radiated can be even greater.

Apart from pixel TFT, TFTs can also be convenient at the periphery of the screen, for example to make row and column controllers. The row controllers must have superior performance to process video signals. In some embodiments, SAC provides an area of sufficient crystallized material to integrate the desired controllers into the periphery of the screen. In other modalities, the non-periodic ALS pulse may be followed by independent crystallization measures to more fully crystallize the periphery of the screen. This could be done using the same laser and optical path by performing conventional ELA scanning in those regions. Alternatively, this could be done using a solid state laser formed of a narrow linear beam to perform sequential side solidification ("SLS") or ELA. Alternatively, a 2D projection radiation tool for performing for example 2-shot SLS (i.e., two laser pulses per unit area, as shown in U.S. Patent Application Serial No. 12 / 063,814 entitled "Systems and Methods for uniform lateral sequential solidification of fine films using high frequency lasers, "filed October 31, 2008) or point SLS (ie, SLS using a mask with a dot pattern as shown in U.S. Patent No. 7,645,337 entitled "Systems and methods for creating films of controlled crystallographic guidance" issued on January 12, 2010). This could be integrated into the same tool to benefit from the precision stages. As used in the present, a firing process x refers to radiate each specific area of the film x times.

As described above, the selective crystallization area involves crystallizing only the regions of interest eg an electronic device of the matrix or circuit type. Thus, the locations of the crystallized regions must be aligned with respect to the locations of the nodes in the electronic circuit or device of the matrix type. Consequently, in order to implement the SAC, sample alignment techniques should be applied. The step of the alignment of the sample can be achieved according to various techniques. In one technique, sample alignment can be established using a crystallization system that also has the ability to place the sample in such a way that the position of the sample can be reproduced in other processing steps for the fabrication of electronic devices. A common way is when the panel is equipped with fiducial marks or alignment that are detected before crystallization and to which the crystallization process is aligned. Such exemplary alignment methods are used in lithographic processes to produce thin film transistors where precision submicrometrica is in superimpose diverse characteristics of said devices. The sample alignment in SAC does not need to be as accurate as in lithography. For example, the crystallized region may be larger than the region of interest by several microns or ten or more microns on each side.

In another technique, the alignment of the sample is established by detecting the location of crystallized regions prior to the manufacture of the electronic devices. The location can be achieved by detecting regions where electronic components will be placed. Regions can be detected because the change from amorphous to crystalline can be microscopically visible as a result of a change in optical properties.

A sample alignment system can include an automated system for detecting fiducials and aligning the sample to a known position with respect to the fiducial. For example, the system may include a computing arrangement to control movement and respond to an optical detector that can detect fiducials in the film. The optical detector can be, for example, a CCD camera.

Crystallization by uniform partial melting of Si amorfo films PECVP As we have mentioned previously, partial melting crystallization techniques are those in which one or more radiations are used to crystallize a silicon film in which at least the last pulse does not induce complete melting of the film. In some embodiments, a method of partial melting by flood radiation or producing a uniform fine grain crystalline film or producing a precursor film by a method of non-periodic pulse radiation may be used. The method of partial melting by flood radiation can be a partially partial two-shot fusion process in which an amorphous silicon film devoid of any pre-existing crystallites (eg, a PECVD film) is transformed into two steps in a crystalline film uniform fine grain with grains with average side dimensions that exceed the thickness of the film. The method of partial melting by flood radiation can also be a partial fusion process of a single shot of prolonged duration in which an amorphous silicon film lacking any pre-existing crystallite (eg, a PECVD film) is transformed into a fine grain uniform crystalline film with grains with average side dimensions less than the thickness of the film.

The work of Professor James Im has shown that super lateral growth ("SLG") can occur in single shot radiation processes with an energy density close to the full melting threshold so that an "almost complete fusion" is obtained ( Im et al, APL 63, 1993, p. 1969) giving as resulting in lateral growth of grains with low density of defects between the grains. Such material can be used to create TFT with mobilities up to 100 cm2 / Vs. However, the TFT uniformity of this material is poor, since the grain size is very sensitive to (1) the pulse energy density, (2) the inhomogeneities in the precursor film, and (3) if a totally amorphous film, the stochastic nature of the crystal nucleation process. Multiple radiations in this SLG regimen, however, can result in grains of more uniform sizes. This is possible thanks to the formation of the roughness of the periodic surface in the film according to the wavelength of the radiated light, resulting in a process of self-stabilization. This has been marketed as ELA, commonly by a linear beam. As noted above, the ELA process is a cumulative process in an initially non-uniform polycrystalline film converging to a more uniform state due to multiple radiations in the almost complete melting regime. However, the ELA process can be more effective if the initial polycrystalline state is uniform.

As we have commented previously, a more uniform polycrystalline film can be obtained by means of a UGS system or an ELA system. Non-periodic pulses in the regions of interest are not radiated with the edges of the beam. However, even the regions initially radiated with the upper portion of the ray may suffer from non-uniformity as a result of heterogeneities in the precursor film and, in the case of a completely amorphous film, the stochastic nature of the crystal nucleation process. . The present disclosure relates to methods and systems for performing partial melt crystallization to create an initial crystallized uniform polycrystalline film which may be beneficial to increase the efficiency of the ELA processes described above (conventional and non-periodic pulses). In other embodiments, the material obtained from PMC with greater uniformity can in itself be used to create thin film electronic devices without further processing of ELA. This can be beneficial in situations where lower performance thin film devices (eg, less than 100 cm2 / Vs or 10 cm2 / Vs) are sufficient but the uniformity of the film is still critical.

Partial melting crystallization (ie, crystallization at energy densities below the almost complete melting threshold) was previously described for amorphous Si films deposited by LPCVD in Im and Kim, Phase transformation mechanisms involved in the crystallization of amorphous silicon film excimer laser, Appl. phys Lett. 63, (14), October 4, 1993. This study indicated that Si LPCVD films are not completely amorphous and there are small crystallites in the films that promote crystallization. Due to the high density of grains, the lateral distance between crystallites is extremely small and crystal growth occurs predominantly in a direction perpendicular to the plane of the film. The very small size of the grains makes this material attractive to make TFT uniform. Such crystallization of LPCVD films in a single shot is what is known as UGS methods that are performed with flood radiation tools that are also capable of synchronized radiation in the laser pulse phase (see U.S. Patent Application No. 2006 publication). -0030164 A1, entitled "Process and system for laser crystallization processing of film regions on a substrate to minimize edge areas and a structure of those film regions" using a two-dimensional projection system and the North American patent application Publication No. 2007-0010104 A1, entitled "Processes and systems for laser crystallization processing of film regions on a substrate using a linear type ray and the structures of those regions of the film" using an ELA lightning system linear).

Potentially, this can be a method for manufacturing LTPS devices with very high performance. Such devices are currently considered products of UD-LCD TV (for example approximately 2000 x 4000 pixels, 480 Hz and 80") so it is concluded that the amorphous silicon has an insufficient level of performance (approximately 1 cm2 / Vs for a TFT Yes of channel n compared to 30 or even 50 cm2 / Vs for UGS TFT of channel n).

The PMC microstructure that has very small columnar grains in no way achieves its partial melting energy density regime. Studies have shown that it can not be used whose partial melting crystallization as currently understood in the manufacture of TFT LTPS of small uniform grains. ariucci et al (Thin solid films 427 (2003) 91-95) for example shows that very heterogeneous and partially highly defective materials can be obtained (defective nuclei surrounded by larger and cleaner grains through lateral growth).

Figure 8A shows an AFM scan of the surface of a film after a radiation at the lower end of the PMC regime. It shows the disc-shaped structures surrounded by large protuberances indicative of lateral growth and correspondingly lateral mass flow as a result of Si expansion after solidification. Figure 8B is an illustration of the crystal structure in Figure 8A. The crystal structure at 8B has a defective core 800. This structure is the result of a low density of nucleation events that promote lateral crystallization and result in disk-like structures. The conditions of initial growth are far from equilibrium. As the crystals are highly defective. As the growth fronts move to each other, enough heat is released and leads to significant reheating of the film. Overheating can result in lateral growth with less defect density.

Figure 8C shows an AFM scan of the surface of a film after radiation at a higher energy density but still in the PMC regime. Figure 8D is an illustration of the crystal structure of Figure 8C. Here, the additional heat introduced from the higher energy density radiation results with the defective core regions that were formed in the initial stages of the phase transformation. The melting threshold of the defective core region is smaller than the outer ring of low defect density and as such preferably melts. The re-growth in these energy densities will start in the outer ring and proceed inward. This start produces a small protrusion in the center as a result of Si expansion after solidification. These protuberances are visible in the scan of the AFM in Figure 8C. The re-fusion of the defective core regions can result in films that are more uniform. Figure 8D is an illustration of the crystal structure obtained at sufficient energy densities for almost complete melting of the film. Figure 8E shows a circular region that is formed laterally to the crystallization of a non-molten seed.

The secondary fusion of the defective core regions may be influenced by the temporal profile of the laser pulse. For example, the excimer lasers available from Coherent, Inc. (Santa Clara, CA) tend to have a temporal profile that shows intensity peaks. The first peak may lead to the initial explosive crystallization of the film, while the second peak may result in selective re-fusion with defective nuclei of the regions formed during the initial stages. The temporal profile of the laser is known to be variable with time, especially with the aging of the laser gases. Ultimately, over time, a third peak of intensity may appear. Thus, while the material after the core melts again can be more uniform, it is not easily reproducible during many pulses of a laser tool. Other lasers may have only a single intensity peak and the details of re-fusion within the same pulse will likely be different.

One way to improve the reproducibility of this microstructure is to radiate the film twice. The first pulse can be optimized to obtain the defective core material, while the second pulse can be optimized to re-merge and thus clean the central regions. This can be done by two scans or a stage and radiate the procedure in which two pulses are radiated at each location before the platform moves to the next location.

The present disclosure relates to a system for providing such a partial fusion crystallization process by two-part radiation in a more efficient manner, namely in a single scan. An ELA system of non-periodic pulses can be used to generate a first laser pulse of the two-part process to obtain an intermediate microstructure that has large grains but poor uniformity throughout the film, while a second pulse is used to clean the intermediate microstructure to create a definitive uniform film. The present method teaches the delayed activation of the second pulse (and possibly the fluence control of the first or second pulse) to achieve a window of energy density optimized for the re-fusion core regions. The late trigger has been suggested before, but only to mimic the extension of the pulse duration and without optical losses through mirrors. Since the pulses are close and can overlap, this means that the film is not completely cooled or possibly is not yet fully solidified at the arrival of the second pulse, resulting in a more efficient use of energy density. In addition, the energy densities of the first and second pulses can be the same or they can be different. However, because the film can not be completely cooled before the arrival of a second pulse, the film may experience a different degree of fusion from the second pulse compared to the first pulse.

The starting films are typically Si films on glass coated with SiO2, quartz wafers, or Si-oxidized, with a thickness of about 40 nm to 100 nm or even up to 200 nm. Thinner films are generally preferred since the deposition time is reduced and the energy density necessary to reach a desired level of fusion is decreased. The pulses can have pulse durations of approximately 30 ns FWHM or more for example up to 300 ns FWHM or more. Generally, shorter pulses are more efficient in melting Si films since less heat is lost to the underlying substrate and higher performance can be established. The films can be radiated over the entire density of the partial fusion energy.

In another embodiment the disc-shaped regions are completely avoided while using films devoid of microcrystallites (as obtained by PECVD). Disk-shaped regions can be avoided by increasing the density of nucleation. A higher nucleation density can lead to more vertical crystallization processes, resulting in less lateral growth and less lateral mass flow. A higher nucleation density can be achieved by changing to longer pulse durations because with long durations of long pulses, the amorphous Si melting front moves more slowly. As it becomes visible in the response function of the interface ("IRF") shown in Figure 9, (which describes the speed of the solid-liquid interface with respect to its temperature) this means that the temperature of the same it is more supercooled with respect to the melting temperature of crystalline Si txm. The IRF in Figure 9 shows the temperature of the x-axis and the speed of the glass front on the y-axis. The solidification is the region of and positive of the graph and the fusion is the region and negative of the graph. The dotted line corresponds to amorphous silicon, while the solid line corresponds to crystalline silicon.

Thus, during a long 900 pulse with slow fusion characteristics, nucleation begins rapidly and under deep supercooling conditions as indicated at point 905 of the IRF curve of Si amorphous. From the classical theory of nucleation it is known that in deep supercooling results in higher nucleation rates. Thus, a large number of nuclei are formed within a short time and before the film begins to overheat as a result of the release of heat of fusion as the nuclei begin to grow (a phenomenon known as recalescence). This high nucleation density substantially eliminates the lateral growth of the region because the nucleation growth will occur in the vertical direction. Substantial lateral growth can create a less homogeneous structure and an uneven surface of the film. Thus, by using long lasting pulses, which impart less energy per unit of time in the film, a film similar to that obtained with (some) LPCVD films can be obtained, where there are previously high densities of microcrystallites.

With a brief pulse 910, on the other hand, the fusion front moves quickly and is less perennial. The condition schematically corresponds to 915 of the IRF. While supercooling is less than films radiated with long pulses, it is still sufficient for nucleation to occur, albeit at a lower rate. Therefore, fewer cores are formed in the short time interval before an important recalescence occurs resulting in additional heating of the film at temperatures where nucleation is stopped. Due to the lower density of nucleation, these types of films will experience more lateral growth and this will result in heterogeneous crystal growth.

The regular excimer laser pulse may be short enough to allow the short pulse stage, whereas, using the 8x pulse extender (to create a FWHM pulse of approximately 300 ns), pulses may be created to be long enough to move in the long pulse stage. Alternatively, the elongated pulse can be created using multiple laser tubes each fired in short sequence to induce a single melting and solidification cycle.

Therefore, a homogeneous crystalline film can be obtained through a partial pulse fusion process using long pulses with slow melting characteristics. This film can be used as a precursor film for a conventional ELA or non-periodic pulse process.

Crystallization by complete fusion In another aspect, the radiation in the complete melting regime is used to generate a uniform fine grain crystalline film or to produce a polycrystalline film initially crystallized which will benefit the subsequent cumulative process of ELA. Full-melt crystallization (CMC) is a technique in which single-shot radiation is used to completely melt Si films, and then the film is crystallized through nucleation (see US application 10 / 525,288, entitled "Process and system for laser crystallization processing of film regions on a substrate to provide substantial uniformity and structure of those film regions"). CMC is what is known as UGS methods that are performed with radiation tools that are also capable of synchronized radiation in the laser phase of flooding pulses (see US application 10 / 525,297, entitled "Process and system for laser crystallization processing. of regions of film on a substrate to minimize edge areas and a structure of those regions of film, "using a 2D projection system and the North American application 11 / 373,772 entitled" Processes and systems for laser crystallization processing of regions of film on a substrate using a linear type ray and structures of those regions of the film, "using an ELA system of linear ray).

The CMC method described here focuses on causing heterogeneous nucleation in a thin film to form Si films of equiaxed fine grains with few defects. The system uses pulses of high energy density, for example, more than 1.3 to 1.4 times the melting threshold completed of the film. The processing is done in the ambient air or any atmosphere that contains oxygen. The process can be performed by films with a surface layer of oxide or PAC of less than about 50 nm in thickness. The system uses pulses with relatively long durations, from about 80 ns to about 500 ns (for example, 200 ns or 400 ns) in combination with a relatively thin Si film (in the range of 100 nm to 300 nm) in wafers of Si02 crystal, quartz. By selecting the process parameters to induce a certain desired scenario of heterogeneous nucleation, instead of a homogeneous nucleation step described in the prior art, nucleation can be achieved both at the interface between the film and the oxide surface layer and the film and the substrate. As a result of the aforementioned parameters, low defect density crystals can be formed.

The described CMC method can be used for the manufacture of LTPS low performance devices with a very high gain. These devices are currently considered for UD-LCD TV products (for example, approximately 2000 x 4000 pixels, 480 Hz, 80 inches) for which amorphous silicon is considered to be underperforming (approximately 1 cm2 / Vs for TFT channel n of amorphous Si compared to up to 30 or even 50 cm2 / Vs TFT of channel n of UGS).

It is known that complete fusion results in a variety of nucleic acids induced by nucleation depending on the radiation conditions and the sample configuration; a description of the process can be found in Hazair S., et al., "Solidification initiated by the nucleation of thin films of Si," Mater. Res Soc. Symp. Proc. Vol. 979 (2007). Many of these microstructures are characterized by a high degree of heterogeneity (variable grain sizes, highly defective regions), which will result in poor uniformity of the devices. For example, the subject of the Hazair documentary is the formation of flower-shaped grains (fig-Si) in which a defective core region is surrounded by a ring of low density grain defects in the shape of petals.

A particular microstructure, however, seems to be an exception to this and was first described in S.R. Stiffler, o.m. Thompson and P.S. Peercy, Phys Rev. Lett. 60, 2519 (1988). This microstructure consists of small grains uniformly distributed throughout the thickness of the film and with a density of defects between grains very low. It is expected that said microstructure results in good uniformity of the device and possibly a reasonable level of device performance. This is true even for lower gate TFT because, unlike many other ways to prepare small grain Si (including deposition techniques), the crystals in and near the bottom have low defects density and larger size. However, questions remain about the mechanisms of formation of this crop and therefore the conditions required to obtain this reproducibility.

The Si of small equiaxed grain (sec-Si) was described by Stiffler as the result of homogeneous nucleation, that is, the nucleation of solids along most of the liquid instead of only at the interfaces. Stiffler bases his conclusions on a combination of transient reflectance data ("TR") and transient conductance data ("TC") that showed a simultaneous drop in front-side reflectance and film conductance. This was held to indicate nucleation throughout most of the film. For twenty years it has been the accepted model to explain the presence of grains within most of the film (ie, not rounded the surface or the lower interface). Recently, based on TR studies, it has been discovered that the Striffler model is inaccurate.

The present TR studies instead present a model where it has been postulated that seg-Si is the result of heterogeneous nucleation (ie, on an interface) followed by volumetric recalescensia, re-fusion and re-solidification of defective core structures . Thus, the initial stages of this scenario are equivalent to those that lead to flg-Si, with the difference that the defective core regions will melt and solidify into grains of low density of defects to form seg-Si For the Stiffler data, the characterization of the microstructure is based on flat images SEM TEM and AFM of top view. However, this is insufficient to explain all the characteristics of the TR data. Specifically, the Stiffler model was unable to explain the fall in posterior TR ("BTR") that occurred before the fall in the frontal TR ("FTR") that could be observed from the experiments in the vacuum atmosphere and with the elimination of the surface layer of native S02 before the laser radiation.

At present, based on the characterization of the TEM microstructure in the lower plane as well as the transverse view, it has been determined that such a fall of TR results in a microstructure with smaller grains near the lower zone which seems to grow upwards and It gets bigger at the top of the movie. On the other hand, the almost simultaneous fall of BTR and FTR is a necessary (but not sufficient) condition for the formation of the seg-Si microstructure as was observed for the first time by Stiffler (and it is also expected to be the most optimal for make TFT uniforms).

Commonly, it is understood that heterogeneous nucleation will take place only at the interface of the lower part of the film. The fall of the front TR corresponds to the appearance of the nucleation of the upper interface (that is, on and near the surface) of the film. Next, a simultaneous appearance of the nucleation on both sides of the film (as evidenced by the simultaneous decay of TR signal on the front and back sides of TR) produces approximately twice the amount of latent heat that is released to the film and therefore a much more effective / extensive re-f u s i / n / re -so I i d i f i cation of the regions of defective nuclei. The nucleation in and near the surface requires the presence of an interface. An interface of this type could be for example with an (native) oxide. These oxide films may be present before radiation or they may be formed during radiation when oxygen is present. Depending on the atmosphere, other surface reactions may occur that can lead to the formation of suitable interfaces for nucleation. further, it was discovered that without that upper layer (for example, by removing native oxide) and the ability of said upper layer to form during radiation (for example, by radiation under vacuum), in fact no surface nucleation occurred and it was not formed according to S-like the one observed by Stiffler. Finally, in some radiated samples with relatively low energy density, a simultaneous fall of TR signal was observed, but no seg-Si Stiffler was observed. It is currently believed that this may be the result of complete remelting of the solids formed through nucleation at the upper interface. In addition, thinner films of 100 nm can also see a simultaneous fall of TR, however the amount of latent heat in the volume of the film seems insufficient to cause a very effective / extensive re-melting / re-solidification. of defective core regions.

Figure 10A and 10B represent the results of recent TR studies. Figure 10A depicts FTR and BTR of 150 nm of amorphous Si on a glass substrate without surface oxide layer under vacuum. The bottom line of the 1400 chart is the radiation experienced by the film. The above lines are reflectance values for different CMT values. The x-axis of Figure 10A is the nanosecond time, the y-axis is a normalized reflectance value. Figure 10B is similar to 10A except that Figure 10B shows results in the air. Figure 10B shows that the BTR signal drops (a series of signals found in the lower part of the graph above the laser signal) before the FTR drop below the energy density of 1.38 CMT in which the FTR signal it seems to begin to fall simultaneously to the BTR. Thus, even in the non-empty scenario, more energy is required to obtain microstructure of sec-Si. As shown in Figure 1 OA and 10B, because the difference in reflectance between solid and liquid is so great, the beginning of the transformation from solid to liquid and vice versa can be distinguished from the data TR. The heterogeneous nucleation can be deduced taking into account location and BTR data and the resulting microstructure (shown in Figure 11 B). Figure 11 depicts a nanosecond time plot (x axis) versus normalized reflectance values (y axis) for an Si film of 200 nm in the air at 1.32 CMT 1500 and in a vacuum in 1.4 CMT 1510. Figure 11 B is an image of the microstructure obtained in the air environment. Figure 11C is an image of the microstructure obtained in the vacuum environment. As can be seen in the two figures, Figure 11 B shows large crystals throughout the 1520 thickness of the film. Figure 11 shows good quality of the glass near the surface of the film, but poor little crystals near the interface with the 1540 substrate. Thus, it can be seen that the true sec-Si 3D is obtained in the air where the reaction can occur surface to form the oxide layer for the heterogeneous nucleation on the surface as well as at the bottom interface, not in the vacuum where the heterogeneous nucleation can occur only at the bottom of the interface.

The present method is of special interest for the manufacture of lower gate TFT because unlike many other ways of preparing small grain Si (including deposition techniques), the crystals in and near the bottom have the low density of defects and bigger size. Therefore, the typical lower LTPS TFT gate suffers from low mobility and perhaps also high leakage current. The manufacture of TFT bottom door requires the formation of a stamped metal film (the gate) under the Si film and separated from it by an insulating layer (gate dielectric). During laser radiation, one of those metal films will act as a heat sink and will result in a displacement of the energy density of the full local melting threshold (CMT). It was found that the condition to arrive at the formation of seg-Si remains the same whenever this local displacement in CMT is taken into account. For example, for a metal with a thickness of 100 nm separated by the silicon film of an oxide film of 100 nm thick, the displacement at the full melting threshold could normally be 15% to 20% higher. A condition for the formation of sec-If so, radiate with an energy density greater than 1.3 to 1.4 times the local CMT. Care should be taken that the energy density is not too high to cause damage to the surrounding film, it has no heat reducers through agglomeration or ablation. For example, for a 100 nm thick film on 100 nm thick oxide above a 100 nm metal gate, the film can be radiated at the 1.4 times local full melting threshold or between approximately 1.61 and 1.68 times the threshold Full melting of the film that surrounds it, which is below the threshold of damage to the film.

The experimental conditions used by Stiffler are somewhat different from the conditions of the present process. Stiffler uses a shorter laser pulse (30 ns compared to the one described for approximately 80 ns) and also uses more thermally conductive substrates: SOI (Si film on a thin Si02 substrate of 250 nm over Si) or Si over sapphire. Generally, homogeneous nucleation requires very rapid cooling. Process conditions currently described as glass substrates and longer pulses result in a less rapid tempering, therefore a lower probability of homogeneous nucleation and a higher probability of heterogeneous nucleation. The oxide thickness that Stiffler uses is not enough to prevent rapid cooling. Therefore, the glass substrate gives much slower cooling than the Stiffler configuration. Thus, the present method implements useful and practical conditions in which the Stiffier material can be obtained by virtue of the correct understanding of what happens.

Samples created according to embodiments of the present disclosure include Si films on glass coated with SiO2, quartz at 100 to 300 nm (or also oxidized Si wafers). A system based on an excimer laser (308 nm) was used to radiate films with different pulse durations (30 ~ 250 n sec FWHM) and energy densities. On-site analysis is performed by transient reflectance measurements, front and rear. The characterization of the radiated materials was carried out with TEM. See also, Yikang "Update of vacuum experiments: analysis of the microstructure" (September 2, 2009).

EXAMPLES For large diameter televisions, pixel separation can be 660 p.m. With a 600 Hz laser, the scanning speed can thus be ~ 40 cm / s. Such a condition could be achieved by a pulse of 0.8J formed in a beam of 100 m x 75 cm for a pulse of -640 mJ / cm2 assuming an optical efficiency of 60%. Then, using a 4-tube laser, five superimposed scans are needed to reach full crystallization. For a 2.2x2.5 panel, m2 the crystallization time is then three parallel scans x (250 cm / 40 cm / s) x 5 superimposed scans = 93.75 s. Taking an acceleration / deceleration time of 10 seconds between parallel scans and a loading and unloading time. The total process time is then ~ 95 + + 5x5 + 2x 10 + 60 = 200s. More conservatively, a process time of five minutes can be assumed. Then that equals 60/5 x 24 x 30 = ~ 8.5k panels / month.

A conventional shot 20, that is, 20 laser pulses per unit area of the film, the ELA process would require the simultaneous firing of the four laser tubes to obtain a beam of 400 pm x 75 cm. For 20 shots, the scanning speed would be 1.2 cm / s and the crystallization time would be 3 x (250 / 1.2) = 625s. The total time of the process, ignoring the acceleration / deceleration times, is then 625 + 2x10 + 60 = 705s. More conservatively, a process time of 12.5 minutes can be assumed, and the performance is ~ 3.4k panels / month.

While examples of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention. By way of example, it is appreciated that the advance of a thin film in a selected direction can be achieved by keeping the laser beam stopped and moving the film in relation to the laser source, as well as the mode in which the film is stopped and the beam It is moving.

Claims (49)

1. A method of processing a thin film comprising: while a thin film is advanced in a selected first direction, radiate a first region of the thin film with a first laser pulse and a second laser pulse, each laser pulse provides a formed beam and has a fluence that is sufficient to partially melt the thin film and the first region re-solidifies and crystallizes to form a first crystallized region; Y radiate a second region of the thin film with a third laser pulse and a fourth laser pulse, each pulse provides a formed beam and has a fluence that is sufficient to partially melt the thin film and the second region re-solidifies and crystallizes to form a second crystallized region, wherein the time interval between the first laser pulse and the second laser pulse is less than half the time interval between the first laser pulse and the third laser pulse.

2. The method of claim 1, wherein the time interval between the first laser pulse and the second laser pulse is longer than a time interval for a melting and solidification cycle of the thin film.

3. The method of claim 1, wherein each of the first laser pulse and the second laser pulse have the same energy density.

4. The method of claim 1, wherein each of the first laser pulse and the second laser pulse have a different energy density.

5. The rei indication method 1, in which each of the first laser pulse and the second laser pulse achieves the same degree of fusion of the thin layer.

6. The method of claim 1, wherein each of the first laser pulse and the second laser pulse reaches a different degree of melting of the thin layer.

7. The method of claim 6, wherein the thin film comprises an amorphous silicon film lacking pre-existing crystallites.

8. The method of claim 7, wherein the first laser pulse has a sufficient energy density to melt the amorphous silicon film and produce crystal structures having defective core regions.

9. The method of claim 8, wherein the second laser pulse has a sufficient energy density to remelter the defective core regions to produce a uniform fine crystalline film.

10. The method of claim 1, wherein the thin film comprises an amorphous silicon film.

11. The method of claim 1, wherein the thin layer is deposited using one of chemical vapor deposition of low pressure, chemical vapor deposition enhanced with plasma, sputtering and electron beam evaporation.

12. The method of claim 1, wherein the thin film comprises a processed film of silicon.

13. The method of claim 12, wherein the processed silicon film is an amorphous silicon film lacking pre-existing crystallites which has subsequently been processed according to a method comprising: while advancing the amorphous silicon film in a selected second direction, radiate the amorphous silicon film with an extended laser pulse having sufficient fluence to partially melt the amorphous silicon film.

14. The method of claim 13 wherein the extended laser pulse is created by sequential accumulation of laser pulses from a multitude of laser sources, wherein the delay between pulses is sufficiently short to induce a single melt and solidification cycle.

15. The method of claim 13, wherein the amorphous silicon film is obtained through chemical vapor deposition enhanced with plasma.

16. The method of claim 13, wherein the extended laser pulse has a pulse length of more than 300 ns the maximum half full width.

17. The rei indication method 12, wherein the processed silicon film is a silicon film processed according to a method comprising: while advancing the silicon film in a selected second direction, radiate the silicon film with a laser pulse with sufficient fluence to completely melt the silicon film.

18. The method of claim 17, wherein the laser pulse is created by accumulation of laser pulses from a plurality of laser sources.

19. The method of claim 1, comprising while advancing the thin film in a second selected direction, radiate a third region of the thin film with a fifth laser pulse and a sixth laser pulse, each laser pulse provides a formed beam and has a fluence that is sufficient to partially melt the thin layer and the third region re-solidifies and crystallizes to form a third crystallized region; Y radiate a fourth region of the thin film with a seventh laser pulse and an eighth laser pulse, each pulse provides a formed beam and has a fluence that is sufficient to partially melt the thin layer and the fourth region re-solidifies and crystallizes to form a fourth crystallized region, in the time interval between the fifth laser pulse and the sixth laser pulse is less than half the time interval between the fifth laser pulse and the seventh laser pulse.

20. It is the method of claim 19, wherein the second selected direction is opposite to the first selected direction and the third region is superimposed on the second region and the fourth region is superimposed on the first region.

21. The method of claim 19, wherein the second selected address is the same as the first selected address and the third region is superimposed on the first region and the fourth region is superimposed on the second region.

22. The method of claim 19, which consists in moving the thin layer in a direction perpendicular to the first selected direction before advancing the thin film in the second selected direction.

The method of claim 1, wherein each laser pulse comprises a linear beam with an upper part having a uniform energy density.

24. The method of claim 1, wherein each laser pulse comprises a pulse of flood radiation.

25. A thin film processed according to the method of claim 1.

26. A device composed of a thin film processed according to the method of claim 1, according to which the device comprises a plurality of electronic circuits placed within a plurality of thin film crystallized regions.

27. The device of claim 26, wherein the device consists of a display device.

28. A system for processing a thin film using non-periodic laser pulses comprising: primary and secondary laser sources for generating laser pulses; a work surface for securing a thin film on a substrate; a platform for moving the thin layer with respect to the pulses of the beam and creating a direction of propagation of the laser beam pulses on the surface of the thin layer; Y a computer having processing instructions to synchronize the laser pulses to provide a first region of a thin film loaded on the mobile platform to be radiated with a first laser pulse from the primary source, a second region of the thin film to be radiated with a second laser pulse from the secondary source and a third region of the thin film to be radiated by a third laser pulse from the primary source, where the processing instructions for moving the film with respect to the beam pulses in the propagation direction for radiating the first, second and third regions are provided, where the distance between the center of the first region and the center of the second region is less than half the distance between the center of the first region and the center of the third region, and wherein the first, second and third laser pulses have sufficient fluence to partially melt the thin layer.

29. The system of claim 28, wherein the step moves at a constant speed.

30. A method of converting an amorphous silicon film lacking pre-existing crystallites into a small grain film, the method comprising: While advancing the amorphous silicon film in a selected first direction, radiating the amorphous silicon film with an extended laser pulse has sufficient fluence to partially melt the amorphous silicon film, wherein the small film grain comprises of grains with average lateral dimensions less than the thickness of the film.

31. The method of claim 30, wherein the extended laser pulse comprises a pulse length of more than 300 ns of the maximum full-width medium and is a pulse of flood radiation.

32. The method of claim 30, wherein the extended laser pulse is created by delayed superposition of laser pulses from a plurality of laser sources, the delay between pulses being sufficiently short to induce a single melting and solidification cycle.

33. The method of claim 30, wherein the amorphous silicon film is obtained through chemical vapor deposition enhanced with plasma.

34. A method for processing a thin film, comprising providing a thin semiconductor film on a substrate, the thin layer having a bottom interface located on a lower surface adjacent to the substrate and a top surface opposite the bottom surface; Y radiate the thin layer with a laser beam with an energy density greater than 1.3 times the full melting threshold of the film, the energy density is selected to completely melt the film; wherein at the beginning of the solidification a PAC layer is present to form a surface interface on the upper surface of the semiconductor film; in which after irradiation and complete fusion of the film heterogeneous nucleation occurs at the interface of the upper part and the interface of the lower part, and where after cooling the heterogeneous nucleation forms low silicon grains in defects in the lower surface of the film.

35. The method of claim 34, wherein the laser beam has a pulse duration greater than 80 ns.

36. The method of claim 34, wherein the laser beam has a pulse duration greater than 200 ns.

37. The method of claim 34, wherein the laser beam has a pulse duration greater than 400 ns.

38. The method of claim 34, according to which the semiconductor thin film comprises a silicon film with a thickness ranging from about 100 nm to about 300 nm.

39. The method of claim 34, according to which the substrate consists of glass.

40. The method of claim 34, according to which the substrate consists of quartz.

41. The method of claim 34, wherein the grains consist of small equiaxed grains.

42. The method of claim 34, wherein the energy density of the laser beam is 1.4 times the local full melting threshold.

43. The method of claim 34, wherein the PAC layer is formed by depositing a thin layer on the upper surface of the thin layer prior to radiation.

44. The method of claim 43, wherein the PAC layer consists of an oxide layer with a thickness of less than 50 nm.

45. The method of claim 34, wherein the boundary layer is formed by radiating the thin layer in an oxygenated environment.

46. The method of claim 45, wherein the oxygenated environment consists of air.

47. The method of claim 45, according to which the oxygenated environment consists of only oxygen

48. The method of claim 34, wherein the substrate consists of a metal interlayer film covered by an insulating film and in which the energy density is greater than 1.3 times the full melting threshold of the thin film.

49. A lower gate TFT made in accordance with the method of claim 48 in which the metal interlayer film consists of a gate of the lower part and the insulating film consists of a gate dielectric.