TW202132899A - Substrate, patterning device and lithographic apparatuses - Google Patents

Abstract

A substrate, associated patterning device and a method. The substrate includes at least one periodic alignment mark and at least one neighboring structure. The alignment mark comprises at least a first part having a direction of periodicity in a first direction and at least a second part having a direction of periodicity in a second direction. Over the extent of a scan length of a scanning of a measurement spot over the alignment mark, the alignment mark is such that when a first region of the measurement spot comprises neighboring structure, a second region of the measurement spot comprises no parallel structure to the neighboring structure within the first region. The first region and second region comprise regions which correspond when one is rotated 180 degrees relative to the other within the measurement spot.

Description

Substrate, patterning device and lithography equipment

This description relates to, for example, methods and equipment that can be used to manufacture devices using lithography technology, and to methods of manufacturing devices using lithography technology. This description relates to metrology devices, and more specifically to metrology devices for measuring positions, such as alignment sensors and lithography equipment with such alignment sensors.

The lithography equipment is a machine that coats a desired pattern on a substrate (usually on a target portion of the substrate). The lithography equipment can be used, for example, in the manufacture of integrated circuits (IC). In that case, a patterning device (which is alternatively referred to as a mask or a reduction mask) can be used to produce circuit patterns to be formed on individual layers of the IC. This pattern can be transferred to a target portion (e.g., a portion including a die, a die, or several die) on a substrate (e.g., a silicon wafer). The pattern transfer is usually performed by imaging onto a layer of radiation-sensitive material (resist) disposed on the substrate. Generally speaking, a single substrate will contain a network of adjacent target portions that are sequentially patterned. These target parts are usually called "fields".

In the manufacture of complex devices, many lithographic patterning steps are usually performed to form functional features in a continuous layer on a substrate. Therefore, the remarkable aspect of the performance of the lithography device can properly and accurately place the coated pattern relative to the features placed in the previous layer (by the same device or a different lithography device). For this purpose, the substrate is provided with one or more sets of alignment marks. Each mark is a structure that can later be used to measure the position using a position sensor, which is usually an optical position sensor, or an alignment sensor (both terms are used synonymously).

The lithography equipment includes one or more alignment sensors, and the positions of the marks on the substrate can be accurately measured by the alignment sensors. It is known that different types of marks and different types of alignment sensors come from different manufacturers and different products from the same manufacturer. The type of sensor used in the lithography device is based on a self-referencing interferometer as described in US Patent No. 6,961,116, which is incorporated herein by reference in its entirety. Various enhancements and modifications of the position sensor have been developed, for example, as disclosed in US Patent Application Publication No. 2015-261097, which is incorporated herein by reference in its entirety.

It is desired to improve the alignment mark measured by the alignment sensor, especially one or more selected from the group consisting of: the size of the mark (for example, reducing its size), the scan length above the mark, the amount of the mark Measuring speed, signal processing of signals from markers, and/or performance of markers expressed in terms of reproducibility and/or accuracy.

In one aspect, a substrate is provided, which includes at least one periodic alignment mark and at least one adjacent structure, wherein the alignment mark includes at least a first portion having a periodic direction in a first direction and At least one second part having a periodic direction in a second direction, wherein within a range of a scan length of a scan of a measurement point above the alignment mark, the alignment mark is such that the measurement point When a first area includes an adjacent structure, a second area of the measurement point does not include the parallel structure of the adjacent structure in the first area, and the first area and the second area include the same amount The corresponding area when one area in the measuring point is rotated 180 degrees relative to the other area.

In one aspect, a substrate is provided, which includes at least one periodic alignment mark and at least one adjacent structure, wherein the alignment mark includes at least one first region having a periodic direction in a first direction, and At least one second area having a periodic direction in a second direction, and wherein the periodic direction of the alignment mark at each of its boundaries is not parallel to the at least one region adjacent to the respective boundary A direction of at least one edge defined by an adjacent structure.

In one aspect, a method for designing a periodic alignment mark is provided. The periodic alignment mark specifically has at least a first portion of a periodic direction in a first direction and in a second direction At least one second portion having a periodic direction, the method includes: determining a layout of at least one adjacent structure and a reserved area for an alignment mark; and based on the at least one adjacent to the alignment mark The orientation of the adjacent structure, the scan length to be used to measure the scanning length of one of the alignment sensor and one of the measurement points of the alignment sensor, and the size of the measurement point, determine the design of an alignment mark, the The alignment mark design ensures that a periodic direction of the adjacent adjacent structure captured in a first area of the measurement point is always not parallel to the alignment mark in a second area of the measurement point. In a periodic direction, the first zone and the second zone include the corresponding zones when one zone within the measurement point rotates 180 degrees relative to the other zone.

Also disclosed is a lithography device operable to perform the method as described herein.

The above and other aspects of the present invention will be understood from the consideration of the examples described below.

Before describing the embodiments of the present invention in detail, it is instructive to present an example environment for implementing the embodiments of the present invention.

Figure 1 schematically depicts the lithography apparatus LA. The equipment includes: an illumination system (illuminator) IL, which is configured to adjust the radiation beam B (such as UV radiation or DUV radiation); a patterning device support or support structure (such as a mask table) MT, which is constructed to support The patterning device (such as a mask) MA is connected to a first positioner PM configured to accurately position the patterning device according to certain parameters; two substrate tables (such as wafer tables) WTa and WTb, which Each is constructed to hold a substrate (such as a resist coated wafer) W, and each is connected to a second positioner PW configured to accurately position the substrate according to certain parameters; and a projection system (such as a refractive projection lens) System) PS, which is configured to project the pattern imparted to the radiation beam B by the patterning device MA onto the target portion C (for example, including one or more dies) of the substrate W. The reference frame RF connects various components and serves as a reference for setting and measuring the position of the patterning device and the substrate, and the position of the features on the patterning device and the substrate.

The lighting system may include various types of optical components for guiding, shaping or controlling radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof.

The patterning device support MT holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithography equipment, and other conditions (such as whether or not to hold the patterning device in a vacuum environment). The patterned device support can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterned device. The patterning device support MT may be, for example, a frame or a table, which may be fixed or movable as needed. The patterning device support can ensure that the patterning device is in a desired position relative to the projection system, for example.

The term "patterning device" as used herein should be broadly interpreted as referring to any device that can be used to impart a pattern to the radiation beam in its cross-section so as to produce a pattern in the target portion of the substrate. It should be noted that, for example, if the pattern imparted to the radiation beam includes phase shift features or so-called auxiliary features, the pattern may not exactly correspond to the desired pattern in the target portion of the substrate. Generally, the pattern imparted to the radiation beam will correspond to a specific functional layer generated in the target portion in the device (such as an integrated circuit).

As depicted here, the device is of the transmissive type (for example, using a transmissive patterning device). Alternatively, the device may be of the reflective type (for example, using a programmable mirror array of the type mentioned above, or using a reflective mask). Examples of patterned devices include masks, programmable mirror arrays, and programmable LCD panels. Any use of the term "reduced mask" or "mask" herein can be regarded as synonymous with the more general term "patterned device". The term "patterning device" can also be interpreted as a device that stores the pattern information used to control such a programmable patterning device in digital form.

The term "projection system" as used herein should be broadly interpreted as covering any type of projection system suitable for the exposure radiation used or other factors such as the use of immersion liquid or the use of vacuum, including refraction, reflection , Catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof. Any use of the term "projection lens" herein can be regarded as synonymous with the more general term "projection system".

The lithography equipment may also belong to the following type: at least a part of the substrate may be covered by a liquid (for example, water) having a relatively high refractive index, so as to fill the space between the projection system and the substrate. The immersion liquid can also be applied to other spaces in the lithography device, such as the space between the mask and the projection system. The immersion technique is well known in the art to increase the numerical aperture of the projection system.

In operation, the illuminator IL receives a radiation beam from the radiation source SO. For example, when the source is an excimer laser, the source and the lithography device may be separate entities. In such cases, the source is not considered to form part of the lithography device, and the radiation beam is transmitted from the source SO to the illuminator IL by means of a beam delivery system BD including, for example, a suitable guiding mirror and/or beam expander . In other cases, for example, when the source is a mercury lamp, the source may be an integral part of the lithography device. The source SO and the illuminator IL together with the beam delivery system BD (when needed) can be referred to as a radiation system.

The illuminator IL may include, for example, an adjuster AD, an accumulator IN, and a condenser CO for adjusting the angular intensity distribution of the radiation beam. The illuminator can be used to adjust the radiation beam to have the desired uniformity and intensity distribution in its cross section.

The radiation beam B is incident on the patterning device MA held on the patterning device support MT, and is patterned by the patterning device. After having traversed the patterning device (eg, mask) MA, the radiation beam B passes through the projection system PS, and the projection system PS focuses the beam onto the target portion C of the substrate W. By means of the second positioner PW and the position sensor IF (for example, an interferometric measuring device, a linear encoder, a 2-D encoder or a capacitive sensor), the substrate table WTa or WTb can be accurately moved, for example, to The different target parts C are positioned in the path of the radiation beam B. Similarly, the first positioner PM and another position sensor (which is not explicitly depicted in FIG. 1) can be used, for example, to compare the path of the radiation beam B after mechanical extraction from the mask library or during scanning. Position the patterning device (e.g., mask) MA accurately.

The patterning device alignment marks M1, M2 and the substrate alignment marks P1, P2 can be used to align the patterning device (such as the mask) MA and the substrate W. Although the substrate alignment marks as illustrated occupy dedicated target portions, the substrate alignment marks may be located in the spaces between the target portions (these marks are referred to as scribe lane alignment marks). Similarly, in the case where more than one die is provided on the patterning device (eg, mask) MA, the patterning device alignment mark may be located between the die. Smaller alignment marks can also be included in the die among the device features. In this case, it is necessary to make the marks as small as possible and do not require any imaging or procedure conditions that are different from adjacent features. The following further describes the alignment system for detecting alignment marks.

The depicted device can be used in multiple modes. In the scanning mode, when the pattern imparted to the radiation beam is projected onto the target portion C, the patterning device support (for example, the mask stage) MT and the substrate stage WT are simultaneously scanned (that is, a single dynamic exposure) . The speed and direction of the substrate table WT relative to the patterning device support (for example, mask table) MT can be determined by the magnification (reduction ratio) and image reversal characteristics of the projection system PS. In the scanning mode, the maximum size of the exposure field limits the width of the target part (in the non-scanning direction) in a single dynamic exposure, and the length of the scanning motion determines the height of the target part (in the scanning direction). As is well known in the art, other types of lithography equipment and operating modes are possible. For example, the stepping mode is known. In the so-called "unmasked" lithography, the programmable patterning device is kept stationary but with a changing pattern, and the substrate table WT is moved or scanned.

Combinations and/or variants of the above-described usage modes or completely different usage modes can also be adopted.

The lithography equipment LA belongs to the so-called dual stage type, which has two substrate tables WTa, WTb and two stations (exposure station EXP and measurement station MEA), and the substrate tables can be exchanged between the two stations. . While exposing one substrate on one substrate stage at the exposure station, another substrate can be loaded on the other substrate stage at the measuring station and various preparatory steps are performed. This achieves a significant increase in the output of the equipment. The preliminary step may include using the level sensor LS to map the surface height profile of the substrate, and using the alignment sensor AS to measure the position of the alignment mark on the substrate. If the position sensor IF cannot measure the position of the substrate table when the substrate table is at the measuring station and at the exposure station, a second position sensor can be provided to enable tracking of the substrate table at two stations The position relative to the frame of reference RF. Instead of the dual stage configuration shown, other configurations are known and available. For example, other lithography equipment that provides a substrate stage and a measuring stage are known. These substrate stages and measurement stages are connected together when the preliminary measurement is performed, and then they are not connected when the substrate stage undergoes exposure.

FIG. 2 illustrates the steps for exposing a target portion (such as a die) on the substrate W in the dual stage apparatus of FIG. 1. The left side of the dashed box shows the steps performed at the measuring station MEA, and the right side shows the steps performed at the exposure station EXP. Sometimes, one of the substrate tables WTa, WTb will be at the exposure station and the other at the measurement station, as described above. For the purpose of this description, it is assumed that the substrate W has been loaded into the exposure station. At step 200, a new substrate W′ is loaded into the device by a mechanism not shown in the figure. The two substrates are processed in parallel in order to increase the throughput of the lithography equipment.

First, referring to the newly loaded substrate W', this substrate can be a previously unprocessed substrate, which is prepared using a new photoresist for the first exposure in the device. However, generally speaking, the described lithography process will only be one of a series of exposure and processing steps, so that the substrate W'has passed through this equipment and/or other lithography equipment several times, and can also undergo subsequent processes . Especially for the problem of improving the stacking performance, the task is to ensure that the new pattern is accurately applied in the correct position on the substrate that has undergone one or more cycles of patterning and processing. These processing steps gradually introduce distortions into the substrate, and these distortions must be measured and corrected to achieve satisfactory stacking performance.

The previous and/or subsequent patterning steps (as just mentioned) can be performed in other lithography equipment, and the previous and/or subsequent patterning steps can even be performed in different types of lithography equipment. For example, some layers in the device manufacturing process that are extremely demanding in terms of parameters such as resolution and overlay can be executed in more advanced lithography tools than other layers that are less demanding. Therefore, some layers can be exposed in an immersion lithography tool, while other layers can be exposed in a "dry" tool. Some layers can be exposed to tools working at DUV wavelengths, while other layers are exposed using EUV wavelength radiation.

At 202, the alignment measurement using the substrate mark P1 and the like and the image sensor (not shown) is used to measure and record the alignment of the substrate with respect to the substrate table WTa/WTb. In addition, the alignment sensor AS will be used to measure several alignment marks across the substrate W'. In one embodiment, these measurements are used to create a "wafer grid" that very accurately maps the distribution of marks across the substrate, including any distortion relative to the nominal rectangular grid.

At step 204, the level sensor LS is used to measure a map of the substrate height (Z) relative to the X-Y position. Conventionally, the height map is only used to achieve accurate focusing of the exposure pattern. It can additionally be used for other purposes.

When the substrate W'is loaded, the recipe data 206 is received to define the exposure to be performed, and one or more attributes of the substrate and the pattern previously obtained on it and to be obtained. The measurements of the substrate position, wafer grid, and height map obtained at 202 and 204 are added to these recipe data, so that the complete set of recipe and measurement data 208 can be transferred to the exposure station EXP. The measurement of the alignment data includes, for example, the X position and the Y position of the alignment target formed in a fixed or nominally fixed relationship with the product pattern of the product as the lithography process. These alignment data obtained just before the exposure are used to generate an alignment model using the parameters that fit the model to the data. These parameters and alignment model will be used during the exposure operation to correct the position of the pattern applied in the current lithography step. The model in use interpolates the position deviation between the measured positions. The conventional alignment model may include four, five, or six parameters, which together define the translation, rotation, and scaling of the "ideal" grid in different sizes. Advanced models that use more parameters are known.

At 210, the substrates W'and W are exchanged, so that the measured substrate W'becomes the substrate W entering the exposure station EXP. In the example device of FIG. 1, this exchange is performed by exchanging the supports WTa and WTb in the device, so that the substrates W and W'are still accurately clamped and positioned on their supports to retain the substrate table and Relative alignment between the substrates themselves. Therefore, once the tables have been exchanged, in order to use the measurement information 202, 204 for the substrate W (previously W') to control the exposure step, it is necessary to determine the distance between the projection system PS and the substrate table WTb (previously WTa) Relative position. At step 212, patterning device alignment is performed using patterning device alignment marks M1, M2. In steps 214, 216, and 218, scanning motion and radiation pulses are applied to successive target positions across the substrate W to complete the exposure of several patterns.

By using the alignment data and height map obtained at the measuring station during the execution of the exposure step, these patterns are accurately aligned with respect to the desired position and especially with respect to the features previously placed on the same substrate. At step 220, the exposed substrate currently marked as W" is unloaded from the device to subject it to etching or other processes according to the exposure pattern.

Those familiar with the art will know a simplified overview of the many extremely detailed steps involved in an example described above as a real manufacturing situation. For example, there will often be separate stages of coarse and fine measurement using the same or different marks, rather than measuring alignment in a single pass. The coarse and/or fine alignment measurement steps may be performed before the height measurement or after the height measurement, or may be performed alternately.

Measuring the position of the mark can also provide information about the deformation of the substrate on which the mark, for example in the form of a wafer grid, is placed. The deformation of the substrate can occur by, for example, electrostatically clamping the substrate to the substrate stage and/or heating the substrate when the substrate is exposed to radiation.

FIG. 3 is a schematic block diagram of an embodiment of the alignment sensor AS. The radiation source RSO provides a light beam RB of radiation having one or more wavelengths, and the light beam RB is turned onto a mark (such as a mark AM on the substrate W) by a turning optics as an illumination spot SP. In this example, the turning optics include a spot mirror SM and an objective lens OL. The width (for example, the diameter) of the illumination spot SP of the illumination mark AM may be slightly smaller than the width of the mark itself.

The radiation diffracted by the marker AM is collimated (via the objective lens OL in this example) into an information-carrying beam IB. The term "diffraction" is intended to include zero-order diffraction (which may be referred to as reflection) from the mark. For example, the self-referencing interferometer SRI disclosed in the aforementioned US Patent No. 6,961,116 interferes with the light beam IB by itself, and the light beam is received by the photodetector PD thereafter. Additional optics (not shown) may be included to provide separate beams in the event that more than one wavelength is generated by the radiation source RSO. The photodetector can be a single element, or it can include multiple pixels as needed. The light detector may include a sensor array.

In this example, the turning optics including the spot mirror SM can also be used to block the zero-order radiation reflected from the mark, so that the information-carrying light beam IB only contains the higher-order diffracted radiation from the mark AM (this is not necessary to measure, But the signal-to-noise ratio can be improved).

One or more intensity signals SI are supplied to the processing unit PU. The X position and/or Y position value of the substrate relative to the reference frame is output by the combination of the optical processing performed in the block SRI and the calculation processing performed in the unit PU.

A single measurement of the described type only fixes the position of the mark within a certain range corresponding to a pitch of the mark. In combination with this measurement, a rougher measurement technique is used to identify, for example, which period of a sine wave is the period containing the marked position. Repeat the same procedure at different wavelengths for the coarser and/or finer levels to improve the accuracy and/or for the stable detection of the mark, regardless of the material used to make the mark and the placement of the mark above it and/ Or the materials below.

The mark or alignment mark may comprise a series of strips formed on or in a layer provided on the substrate or (directly) formed in the substrate. The strips can be regularly spaced apart and act as grating lines, so that the mark can be regarded as a diffraction grating with a known spatial period (pitch). Depending on the orientation of these raster lines, the marker can be designed to allow measurement of the position along the X axis or along the Y axis (which is oriented substantially perpendicular to the X axis). The mark containing the strips arranged at +45 degrees and/or -45 degrees with respect to both the X axis and the Y axis allows the combination of the X amount using the technique described in US Patent Application Publication No. US 2009/195768 For measurement and Y measurement, the publication is incorporated herein by reference in its entirety.

The alignment sensor uses the radiation spot to optically scan each mark to obtain a periodically changing signal, such as a sine wave. The phase of this signal is analyzed to determine the position of the mark, and therefore the position of the substrate relative to the alignment sensor, which in turn is fixed relative to the reference frame of the lithography device. The so-called coarse and fine marks related to different (coarse and fine) mark sizes can be provided, so that the alignment sensor can distinguish between different cycles of the periodic signal and the exact position (phase) within the cycle. Marks with different pitches can also be used for this purpose.

When performing alignment by using an alignment sensor to measure the position of the alignment mark on the substrate, it is necessary to reduce the area (coverage area) of the alignment mark so that many of the alignment marks can be accommodated. On the substrate; included in the die, located between the product structure, where the substrate space is "expensive." Therefore, when scanning alignment sensors (for example, scan marks with insufficient light spots to generate SRI signals), it is necessary to reduce the required scan length on the marks to maintain sufficient accuracy and/ Or reproducibility (repro). In addition, it is still necessary to perform alignment detection on the same mark in the X and Y directions (for example, two directions parallel to the substrate plane) to further reduce the use area (and depending on the situation when measuring both directions at the same time) Reduce alignment time and increase throughput).

To achieve this goal, it is proposed that the alignment mark has a size equivalent to the light spot size of the measurement point of the alignment sensor. Therefore, it is proposed that the maximum range of the mark (such as the maximum length in the X and Y directions) is not more than 50%, not more than 40%, not more than 30%, not more than 20 than the maximum range of the light spot (such as width or diameter). %, not more than 10% or not more than 5%. The mark may be a square (or more generally a rectangle) with a side length that is only slightly larger than the maximum range of the light spot or even the same size as the maximum range of the light spot. The mark may be smaller than the spot size. In various cases, the result is that the light spot is overfilled on the mark during scanning; that is, during at least part of the measurement scan, the adjacent structure of the alignment mark is also included in the light spot.

One problem with overfilling measurement is that adjacent structures affect the accuracy of the measurement. When the mark exclusion area is just larger than the size of the light spot (in two directions), it is inevitable to scan one or more adjacent structures, which affects the measurement position of the mark. This is not desired and should be reduced or minimized. One method is to reduce the scan length. However, the shorter scan length of several detection cycles results in poor reproducibility. Generally, when scanning more cycles, the reproducibility is improved, but then the influence of one or more adjacent structures on the alignment position increases.

Therefore, it is proposed to provide a two-dimensional alignment mark, in which the entire range of the alignment scan length (such as the proposed or predetermined scan length for alignment measurement) of the measurement point on the alignment mark is within the measurement point The periodic direction of any captured adjacent structure (for example, a product structure that may include a periodic pattern) is always not parallel to the alignment mark at the interference zone corresponding to the 180-degree rotation in the measurement point. In this way, for all interference zone pairs within the measurement point (one zone in a pair contains at least one adjacent structure), the other zone of the interference pair will not contain parallel structures.

The concept is based on the basic operation of a self-referencing interferometer SRI that forms the center of many alignment sensors. When performing a partial scan of a mark with an adjacent structure, it is conceivable that the sensor will operate as follows. Obtain an image, and interfere with the image with a 180-degree rotated copy of the image. When the two images overlap and have different (non-parallel) orientation lines (local gratings), the images do not give a signal or the signal is very weak. However, when two images have parallel lines (at the same distance), the images give strong signals. In all the examples described below, it can be observed that for a shorter scan length, at least one adjacent structure is always not parallel to the mark after the 180-degree image rotation (ie, the corresponding 180-degree rotation position within the measurement point) The marked part of the interference.

In one embodiment, this can be achieved by providing a two-dimensional alignment mark in which the periodic direction at each edge is not parallel to the direction of at least one adjacent structure adjacent to the edge. Therefore, the proposed alignment mark can be optimized with respect to the orientation of at least one adjacent structure (e.g., a product structure that may include a periodic pattern).

Figure 4 illustrates several proposals for smaller alignment marks with X and Y detectability, the smaller alignment marks being designed to minimize crosstalk from one or more adjacent structures. In all cases, the periodic direction of adjacent structures is not parallel to the marking structure in which the light spot rotates 180 degrees. For example, each edge may not be parallel to adjacent structures adjacent to the edge.

Figure 4(a) shows a target configuration suitable for embedding in at least one adjacent structure, the at least one adjacent structure including Y-directed adjacent structures NS _Y (shown on the left and right in Figure 4(a)) and X Orient adjacent structures NS _X (shown at the top and bottom sides in Figure 4(a)). The target consists of a square area divided into four triangular areas defined by two diagonal axes. The measurement point MS at the leftmost end of the scan length is also shown. _{The alignment mark is designed so that any adjacent structure (here, adjacent structure NS Y} ) in the measurement point in the first zone IR of the corresponding interference zone pair of the measurement point MS is always not parallel to the corresponding interference zone pair. The alignment marks in the second region IR' are oriented. The corresponding pairs of regions IR and IR' are corresponding, which means that when one region rotates 180 degrees with respect to the light spot of the other region, these regions will overlap.

In embodiments including many of the embodiments disclosed herein, this can be achieved by making the periodic directions in the regions perpendicular to the corresponding peripheral edges of the regions (ie, the edges shared by both the region and the complete target region) , And therefore adjacent to the adjacent structure) the periodic direction of the adjacent structure to achieve. However, those familiar with this technology should realize that other configurations may also achieve the same effect. Figure 4(b) shows a complementary design with all orientations reversed (X vs. Y and Y vs. X).

Figures 4(c) and 4(d) show complementary designs for embedding in at least one adjacent structure, which are all oriented in a single direction (X direction NS _X in Figure 4(c) and Figure 4(d) in the Y direction NS _Y ). In each case, the marker includes a square-in-square configuration, where the inner square area has the same orientation as the adjacent structure, and the outer area is perpendicular to the inner area and adjacent structures. It should be noted that the inner zone does not need to be square, it only needs to be a zone oriented with adjacent structures and (respectively) surrounded by vertically oriented zones.

Figures 4(e) and 4(f) show complementary configurations that replace the configurations depicted in Figures 4(a) and 4(b), respectively. In each case, the configurations include the combination of targets arranged in squares in squares as depicted in Figures 4(a) and 4(b), where Figure 4(e) has Figure 4(a) in its central area. ) And has the goal of Figure 4(b) in its outer area. The goal in Figure 4(f) is the opposite.

Figure 4(g) shows a configuration in which two adjacent sides of the target are surrounded by X-direction adjacent structures NS _X and the other two adjacent sides of the target are surrounded by Y-direction adjacent structures NS _Y. Here, the target includes an outer oblique orientation area (for example, oriented at 45 degrees) and an inner oblique orientation area oriented perpendicular to the outer area (for example, 135 degrees). Here, although it is illustrative, the shape of the inner region is a rhombus. In this example, the measurement point MS is shown to illustrate the relative size of the example relative to the target.

When scanning for any one of the marks illustrated in FIG. 4 close to the center of the mark, the influence of the surrounding structure on the measurement position APD is minimized. This allows sufficient scan length (e.g. some scans on adjacent structures) for acceptable reproducibility. It should be noted that the embodiment of FIG. 4 is only illustrative, and there are many other configurations that can be envisaged within the scope of the present disclosure and depend on the configuration of adjacent structures.

Figure 5 illustrates another embodiment of an alignment mark structure that can be used to help ensure that adjacent structures are not rotated 180 degrees parallel to the light spot. This embodiment can replace or be used in combination with other embodiments described herein. In this embodiment, a smaller alignment mark is proposed relative to the excluded area (the area reserved for alignment without product structure). Figure 5 shows the smaller mark in the exclusion zone (marked as x-direction dimension EZ _X ), and there is a significant gap between the mark and the adjacent structure NS _X. The measurement point MS is also shown, which includes a pair of corresponding interference regions (for example, when one region is rotated 180 degrees with respect to the light spot of the other region). It can be seen that when the first region IR includes the adjacent structure NS _X , the corresponding region IR' does not include structure and therefore there will be no interference signal. However, it should be noted that the benefits of smaller marks will come at the expense of signal strength and reproducibility.

When using a self-referenced interferometer (SRI)-based tool, the effect of one or more of the proposals described herein is to suppress the influence of the surrounding structure at the measured alignment position by an order of magnitude. The self-reference interferometer aligned with the sensor produces an overlap of the relative area of rotation of the mark around the scanning position. By making the mark periodically non-parallel to adjacent adjacent structures rotated by 180 degrees to the light spot, at least one adjacent structure does not interfere and therefore does not contribute to the alignment signal (or at least contributes much less). This effect can be used to suppress the influence from the surrounding structure in the bottom layer or from the same layer of the upper layer.

It is proposed that these methods can be used in combination with one or more of improved fitting methods and smaller light spots.

A method for designing an alignment mark is also proposed. The method includes: determining the layout of at least one adjacent structure (such as a product structure) and a reserved area for the alignment mark; and based on the neighboring adjacent to the alignment mark The orientation of the structure, the scanning length of the measurement point of the alignment sensor used to measure the alignment mark, and the size of the measurement point are used to determine the alignment mark design. The alignment mark design ensures that it is captured within the measurement point The periodic direction of adjacent structures is always not parallel to the periodic direction of the alignment mark in the 180-degree rotation interference position within the measurement point. This can be achieved by indicating the orientation of the adjacent adjacent structures that will be captured in the proposed scan and by appropriately selecting the alignment mark orientation for the alignment mark in the corresponding interference zone of the light spot.

Proposing the described concept can enable X and/or Y detection using underfill marks from a single scan of smaller (eg, 50×50 µm or less, or 2500 µm ^{2 or less) marks.} This method may only require a scan length of 4 to 10 µm to obtain sufficient reproducibility.

The present invention can also be characterized by the following items: 1. A substrate comprising at least one periodic alignment mark and at least one adjacent structure, wherein the alignment mark comprises a periodic direction in a first direction At least a first part and a second part having a periodic direction in a second direction, wherein, within a range of a scan length of a scan of a measurement point above the alignment mark, the alignment mark So that when a first area of the measurement point includes an adjacent structure, a second area of the measurement point does not include the parallel structure of the adjacent structure in the first area, and the first area and the second area The second zone includes the corresponding zone when one zone in the measurement point is rotated 180 degrees relative to the other zone. 2. The substrate as stated in clause 1, wherein the second area includes a portion of the alignment mark, and the portion of the alignment mark includes a periodicity that is not parallel to the adjacent structure in the first area . 3. The substrate as stated in clause 2, wherein the adjacent structure has a periodic characteristic, and the portion of the alignment mark includes the periodicity that is not parallel to the adjacent structure in the first region A periodicity. 4. The substrate as stated in any one of clauses 1 to 3, wherein the periodic direction of the alignment mark at each of its one or more boundaries is not parallel to the direction adjacent to the respective boundary One direction of at least one edge defined by the adjacent structure. 5. The substrate as stated in any one of clauses 1 to 4, wherein the first direction is perpendicular to the second direction. 6. The substrate as stated in clause 5, wherein: adjacent to each of the boundaries of the alignment mark, the periodic direction of the adjacent structure is substantially in the first direction; A part includes an inner region having a periodic direction in the first direction; and the second part surrounds the first part and has a periodic direction in the second direction. 7. The substrate as stated in clause 5, wherein: adjacent to each of a pair of first opposite boundaries of the alignment mark, the periodic direction of the adjacent structure is in the first direction; adjacent In each of a pair of second opposite boundaries of the alignment mark, the periodic direction of the adjacent structure is in the second direction; and the alignment mark includes: a pair of first portions, each portion adjacent to One of the boundaries of the second pair of opposite boundaries is separate and has a periodic direction in the first direction, and a pair of second parts, each part being adjacent to one of the boundaries of the first pair of opposite boundaries One is separate and has a periodic direction in the second direction. 8. The substrate as stated in clause 7, wherein the alignment mark is a rectangle, and each of the parts includes a triangle defined by one of the borders and diagonals of the rectangle. 9. The substrate as stated in clause 8, wherein each of the parts is further divided into sub-parts so that: each of the first part pair has an outer sub-part in the first direction A periodic direction, and a periodic direction in the second direction of an inner sub-part, and each of the second pair of parts has a periodic direction in the second direction of an outer sub-part , And an inner sub-part has a periodic direction in the first direction. 10. The substrate as stated in clause 4, wherein: the adjacent structure has a periodic characteristic; adjacent to each of a pair of first adjacent borders of the alignment mark, the adjacent structure has a periodicity The sexual direction is in a third direction; adjacent to each of a pair of second adjacent borders of the alignment mark, a periodic direction of the adjacent structure is in a fourth direction perpendicular to the third direction; The first part includes an inner zone having a periodic direction in the first direction; and the second part surrounds the first zone and has a periodic direction in the second direction. 11. The substrate as stated in Clause 10, wherein the third direction and the fourth direction are respectively parallel to a first coordinate axis and a second coordinate axis of a coordinate system of the substrate. 12. The substrate as stated in any one of clauses 1 to 11, wherein the first direction and the second direction are respectively parallel to a first coordinate axis and a second coordinate axis of a coordinate system of the substrate. 13. The substrate as stated in any one of clauses 1 to 12, wherein the size of the alignment mark is 50 µm × 50 µm or less, or 2500 µm ² or less. 14. The substrate as stated in any one of clauses 1 to 13, wherein the alignment mark is relatively small relative to an area reserved for it, and the area does not contain adjacent structures, so that the alignment mark is adjacent to There is a gap between the structures; and when the first area of the measurement point includes the adjacent structure, the second area of the measurement point includes the gap. 15. The substrate as stated in clause 14, wherein one of the alignment marks has a size less than 70% of the same size of the area reserved for it. 16. A substrate comprising at least one periodic alignment mark and at least one adjacent structure, wherein the alignment mark comprises at least a first portion having a periodic direction in a first direction and a second direction At least one second portion having a periodic direction, and wherein the periodic direction of the alignment mark at each of its boundaries is not parallel to at least one defined by the adjacent structure adjacent to the respective boundary One direction of the edge. 17. The substrate as stated in clause 16, wherein the first direction is perpendicular to the second direction. 18. The substrate as stated in Clause 16 or Clause 17, wherein the adjacent structure has a periodic characteristic, and the periodic direction of the alignment mark at each of the boundaries is perpendicular to the adjacent The periodic direction of the adjacent structure at the boundary. 19. The substrate as stated in any one of clauses 16 to 18, wherein: adjacent to each of the boundaries of the alignment mark, a periodic direction of the adjacent structure is substantially in the first In a direction; the first part includes an inner region having a periodic direction in the first direction; and the second part surrounds the first part and has a periodic direction in the second direction. 20. The substrate as recited in any one of clauses 16 to 18, wherein each of a pair of first opposite boundaries adjacent to the alignment mark, the periodic direction of the adjacent structure is in the first In a direction; adjacent to each of a pair of second opposite boundaries of the alignment mark, the periodic direction of the adjacent structure is in the second direction; and the alignment mark includes: a first partial pair , Each part is adjacent to one of the boundaries of the second pair of opposite boundaries and has a periodic direction in the first direction, and a second part pair, each part being adjacent to the first pair of opposite boundaries One of the boundaries is separate and has a periodic direction in the second direction. 21. The substrate as stated in Clause 20, wherein the alignment mark is a rectangle, and each of the parts includes a triangle defined by one of the borders and diagonals of the rectangle. 22. The substrate as stated in clause 21, wherein each of the parts is further divided into sub-parts so that: each of the first part pair has an outer sub-part in the first direction A periodic direction, and a periodic direction in the second direction of an inner sub-part, and each of the second pair of parts has a periodic direction in the second direction of an outer sub-part , And an inner sub-part has a periodic direction in the first direction. 23. The substrate as stated in clause 16 or clause 17, wherein: the adjacent structure has a periodic characteristic; adjacent to each of a pair of first adjacent borders of the alignment mark, the adjacent A periodic direction of a structure is in a third direction; adjacent to each of a pair of second adjacent borders of the alignment mark, a periodic direction of the adjacent structure is in a first direction perpendicular to the third direction In four directions; the first part includes an inner zone having a periodic direction in the first direction; and the second part surrounds the first zone and has a periodic direction in the second direction. 24. The substrate as stated in Clause 23, wherein the third direction and the fourth direction are respectively parallel to a first coordinate axis and a second coordinate axis of a coordinate system of the substrate. 25. The substrate as recited in any one of clauses 16 to 24, wherein the first direction and the second direction are respectively parallel to a first coordinate axis and a second coordinate axis of a coordinate system of the substrate. 26. The substrate as recited in any one of clauses 16 to 25, wherein the alignment mark is relatively small relative to an area reserved for it, and the area does not include adjacent structures, so that the alignment mark is adjacent to There are gaps between the structures. 27. The substrate as stated in clause 26, wherein one of the alignment marks has a size less than 70% of the same size of the area reserved for it. 28. The substrate as stated in any one of clauses 16 to 27, wherein the size of the alignment mark is 50 µm × 50 µm or less, or 2500 µm ² or less. 29. A patterning device, comprising a plurality of patterns for forming alignment marks on a substrate, the patterning device is configured to pattern a substrate to obtain as described in any one of clauses 1 to 28 The substrate of the statement. 30. A method for designing a periodic alignment mark having at least a first portion with a periodic direction in a first direction and a periodic direction in a second direction A second part, the method comprising: determining a layout of at least one adjacent structure and a reserved area therein for an alignment mark; and based on the orientation of the at least one adjacent structure adjacent to the alignment mark, To be used to measure the scan length of one of the alignment marks and one of the measurement points of the alignment sensor and the size of the measurement point, determine the design of an alignment mark, and the design of the alignment mark ensures that A periodic direction of the adjacent structure captured in a first area of the measuring point is always not parallel to a periodic direction of the alignment mark in a second area of the measuring point, the first The first zone and the second zone include the corresponding zones when one zone in the measurement point is rotated 180 degrees with respect to the other zone. 31. The method as set forth in clause 30, which includes indicating the orientation of the adjacent adjacent structure to be captured during scanning, and selecting non-parallel to the adjacent for the alignment mark in the corresponding 180 degree rotation area The alignment marks of adjacent structures are oriented. 32. The method as set forth in Clause 30 or Clause 31, which further comprises exposing the periodic alignment mark on a substrate that also includes the adjacent structure at least when all exposure steps are completed. 33. The method as stated in clause 32, wherein the alignment mark comprises any one of the alignment marks contained on the substrate of any one of clauses 1 to 28. 34. A lithography device that is operable to perform the method as stated in item 32 or item 33. 35. The lithography equipment as stated in clause 34, comprising: a patterning device support for supporting the patterning device as stated in clause 29; and a substrate support for supporting One substrate.

In addition, as will be appreciated, the embodiments of the marks described herein are formed on a substrate. Therefore, in one embodiment, the patterning device will have one or more patterns to form an embodiment of the mark. For example, the mask may have one or more patterns formed thereon, and when the patterns are projected onto the resist-coated substrate, the patterns are formed on the substrate to form marks.

Although specific embodiments have been described above, it should be understood that the present invention can be practiced in other ways than those described.

Although the above can specifically refer to the use of the embodiments of the present invention in the context of optical lithography, it should be understood that the embodiments of the present invention can be used in other applications (for example, imprint lithography), and in the context of content Where permitted, it is not limited to optical lithography. In imprint lithography, the topography in the patterning device defines the pattern produced on the substrate. The configuration of the patterning device can be pressed into the resist layer supplied to the substrate on which the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist is cured, the patterning device is removed from the resist, leaving a pattern in it.

The terms "radiation" and "beam" as used herein cover all types of electromagnetic radiation, including ultraviolet (UV) radiation (for example, having a wavelength of or about 365, 355, 248, 193, 157 or 126 nm) and polar Ultraviolet (EUV) radiation (e.g. having a wavelength in the range of 1 to 100 nm), and particle beams such as ion beams or electron beams.

The term "lens" can refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components, as permitted by the context of the content. Reflective components are likely to be used in equipment operating in the UV and/or EUV range.

Although specific embodiments of the present invention have been described above, it should be understood that the present invention can be practiced in other ways than those described. For example, the embodiments of the present invention may take the form of a computer program containing one or more machine-readable instruction sequences to implement all or part of the method as described herein, or use a computer program with such a computer program therein. The form of data storage media (such as semiconductor memory, magnetic disks, or optical disks).

The breadth and scope of the present invention should not be limited by any of the exemplary embodiments described above, but should only be defined according to the scope of the following patent applications and their equivalents.

200: Step 202: Step 204: Step 206: Recipe Data 208: Measurement Data 210: Step 212: Step 214: Step 216: Step 218: Step 220: Step AD: Adjuster AM: Mark APD: Measurement Position AS: Alignment sensor B: Radiation beam BD: Beam delivery system C: Target part CO: Concentrator EXP: Exposure station EZ _X : Dimensions in x direction IB: Information carrying beam IF: Position sensor IL: Illumination system IN : Integrator IR: first zone IR': second zone LA: lithography equipment LS: level sensor M1: patterning device alignment mark M2: patterning device alignment mark MA: patterning device MEA: volume Measuring station MS: measuring point MT: patterning device support NS _X : X-oriented adjacent structure NS _Y : Y-oriented adjacent structure OL: objective lens P1: substrate alignment mark P2: substrate alignment mark PM: first positioning PS: Projection system PW: Second locator RB: Beam PD: Light detector PU: Processing unit RF: Reference frame RSO: Radiation source SI: Intensity signal SM: Spot mirror SO: Radiation source SP: Illumination spot SRI: Self-reference interferometer W: Substrate W': Substrate W": Substrate WT: Substrate table WTa: Substrate table WTb: Substrate table

The embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 depicts the lithography equipment;

Figure 2 schematically illustrates the measurement and exposure procedures in the equipment of Figure 1;

Figure 3 is a schematic illustration of an adjustable alignment sensor according to an embodiment;

4 (a), 4 (b), 4 (c), 4 (d), 4 (e), 4 (f), and 4 (g), which depicts a diagram according to the present invention Several alignment marks of the embodiment; and

Fig. 5 depicts another example of an alignment mark according to an embodiment of the present invention.

IR: Zone 1

IR': second zone

MS: measuring point

NS _X : X directional adjacent structure

NS _Y : Y directional adjacent structure

Claims (17)

A substrate comprising at least one periodic alignment mark and at least one adjacent structure, Wherein the alignment mark includes at least a first part having a periodic direction in a first direction and a second part having a periodic direction in a second direction, Wherein, within the range of a scan length scanned by one of the measurement points above the alignment mark, the alignment mark makes that when a first area of one of the measurement points includes adjacent structures, the measurement point is A second zone does not include parallel structures of the adjacent structures in the first zone, and The first area and the second area include areas corresponding to when one area in the measurement point rotates 180 degrees with respect to the other area. The substrate of claim 1, wherein the second area includes a portion of the alignment mark, and the portion of the alignment mark includes a periodicity that is not parallel to the adjacent structure in the first area. The substrate of claim 2, wherein the adjacent structure has a periodic characteristic, and the portion of the alignment mark includes a periodicity that is not parallel to the periodicity of the adjacent structure in the first region. The substrate of any one of claims 1 to 3, wherein the periodic direction of the alignment mark at each of its one or more boundaries is not parallel to the adjacent structure adjacent to the respective boundary One direction of at least one edge defined. The substrate according to any one of claims 1 to 3, wherein the first direction is perpendicular to the second direction. Such as the substrate of claim 5, where: Adjacent to each of the boundaries of the alignment mark, the periodic direction of the adjacent structure is substantially in the first direction; The first portion includes an inner region having a periodic direction in the first direction; and The second part surrounds the first part and has a periodic direction in the second direction. Such as the substrate of claim 5, where: Adjacent to each of a pair of first opposite boundaries of the alignment mark, the periodic direction of the adjacent structure is in the first direction; Adjacent to each of a pair of second opposite borders of the alignment mark, the periodic direction of the adjacent structure is in the second direction; and The alignment mark contains: A pair of first portions, each portion being adjacent to each of the boundaries of the second pair of opposite boundaries and having a periodic direction in the first direction, and A second part pair, each part being adjacent to each of the boundaries of the first opposite boundary pair and having a periodic direction in the second direction. A substrate comprising at least one periodic alignment mark and at least one adjacent structure, The alignment mark includes at least one first portion with a periodic direction in a first direction and at least one second portion with a periodic direction in a second direction, and The periodic direction of the alignment mark at each of its boundaries is not parallel to a direction of at least one edge defined by the adjacent structure adjacent to the respective boundary. Such as the substrate of claim 8, wherein the first direction is perpendicular to the second direction. Such as the substrate of claim 8 or claim 9, wherein the adjacent structure has a periodic characteristic, and the periodic direction of the alignment mark at each of the boundaries is perpendicular to the adjacent to the boundary The periodic direction of adjacent structures. Such as the substrate of claim 8 or claim 9, where: Adjacent to each of the boundaries of the alignment mark, a periodic direction of the adjacent structure is substantially in the first direction; The first portion includes an inner region having a periodic direction in the first direction; and The second part surrounds the first part and has a periodic direction in the second direction. Such as the substrate of claim 8 or claim 9, where Adjacent to each of a pair of first opposite boundaries of the alignment mark, the periodic direction of the adjacent structure is in the first direction; Adjacent to each of a pair of second opposite borders of the alignment mark, the periodic direction of the adjacent structure is in the second direction; and The alignment mark contains: A pair of first portions, each portion being adjacent to each of the boundaries of the second pair of opposite boundaries and having a periodic direction in the first direction, and A second part pair, each part being adjacent to each of the boundaries of the first opposite boundary pair and having a periodic direction in the second direction. Such as the substrate of claim 8 or claim 9, where: The adjacent structure has a periodic characteristic; Adjacent to each of a first adjacent boundary pair of the alignment mark, a periodic direction of the adjacent structure is in a third direction; Adjacent to each of a second adjacent boundary pair of the alignment mark, a periodic direction of the adjacent structure is in a fourth direction perpendicular to the third direction; The first portion includes an inner region having a periodic direction in the first direction; and The second part surrounds the first zone and has a periodic direction in the second direction. A patterning device includes a plurality of patterns for forming alignment marks on a substrate, and the patterning device is configured to pattern a substrate to obtain a substrate according to any one of claims 1 to 13. A method for designing a periodic alignment mark having at least a first portion having a periodic direction in a first direction and one of a periodic direction in a second direction In the second part, the method includes: Determining a layout of at least one adjacent structure and a reserved area for an alignment mark; and Based on the orientation of the at least one adjacent structure adjacent to the alignment mark, a scan length to be used for measuring a scan of a measurement point of an alignment sensor of the alignment mark and the measurement point Determine the size of an alignment mark design that ensures that a periodic direction of the adjacent adjacent structure captured in the first area of one of the measurement points is always not parallel to one of the measurement points A periodic direction of the alignment mark in the second area. The first area and the second area include areas corresponding to when one area in the measurement point rotates 180 degrees with respect to the other area. The method of claim 15, which further includes exposing the periodic alignment mark on a substrate, and the substrate includes the adjacent structure at least when all the exposure steps are completed. The method of claim 16, wherein the alignment mark includes any one of the alignment marks included on the substrate of any one of claims 1-13.

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