KR20100084029A - Method for forming methla oxide layer and method for manufacturing metal oxide semiconductor thin film transistor - Google Patents

Abstract

The present invention relates to a method for forming a metal oxide layer and a method for manufacturing a metal oxide semiconductor thin film transistor, comprising the steps of preparing a substrate, depositing a metal oxide film on the substrate by a chemical vapor deposition method at a deposition temperature of 20 to 150 degrees and the deposition Provided are a method of forming a metal oxide layer and a method of manufacturing a metal oxide semiconductor thin film transistor, including performing a heat treatment process at a heat treatment temperature higher than the temperature.

As described above, the present invention can increase the film quality of the metal oxide by depositing the metal oxide at a low temperature, and performing heat treatment by a temperature, a time, and a method that will not damage the substrate.

Description

METHOD FOR FORMING METHLA OXIDE LAYER AND METHOD FOR MANUFACTURING METAL OXIDE SEMICONDUCTOR THIN FILM TRANSISTOR}

The present invention relates to a method for forming a metal oxide layer and a method for manufacturing a metal oxide semiconductor thin film transistor, which can improve the film quality of a metal oxide layer prepared at low temperature (about 100 degrees or less) by chemical vapor deposition (CVD). A method and a method of manufacturing a thin film transistor using such a metal oxide layer as an active layer.

Conventionally, insulating materials, semiconducting materials, and conductive materials have been deposited on insulating substrates (for example, glass, transparent plastic, acrylic, and stainless steel coated with insulating films) other than semiconductor substrates to fabricate various devices other than semiconductor devices. This makes it possible to fabricate devices such as thin film transistors on insulating substrates.

However, insulating substrates are more susceptible to heat than silicon substrates. That is, the insulating substrate has a problem in that deformation such as bending at high temperatures (about 300 degrees or more) easily occurs.

Due to such a problem, it is difficult to form a silicon thin film used as an active layer of a thin film transistor on an insulating substrate.

Recently, researches on a technique of using a metal oxide (eg, zinc oxide layer) formed by using a sputter as an active layer of a thin film transistor have been actively conducted. Metal oxides are materials that can implement all three properties of conductivity, semiconductivity and resistance, depending on the oxygen content.

However, when the metal oxide is formed on the insulating substrate through the sputtering method, there is a disadvantage that the thin film characteristics are not uniform for each substrate. In addition, as the number of thin film depositions increases, the composition of the target is changed to change the characteristics of the oxide. Due to such a disadvantage, the sputtering method has a problem in that the target must be frequently changed, resulting in a decrease in productivity and an increase in cost.

In addition, in recent years, active researches have been made to form thin film transistors on flexible substrates in addition to insulating substrates. However, flexible substrates are more susceptible to heat than insulating substrates. Therefore, the metal oxide formation process must be performed at a temperature of about 150 degrees or less. However, when the metal oxide is formed at a low temperature, the film quality of the metal oxide is lowered.

In order to solve the problems described above, after depositing the metal oxide by chemical vapor deposition (that is, organometallic chemical vapor deposition) at low temperature (about 150 degrees or less), rapid heat treatment is performed to prevent deformation of the substrate and to reduce the film quality of the metal oxide. It is an object of the present invention to provide a method for forming a metal oxide layer that can improve, improve productivity, and reduce production costs.

In addition, according to the present invention, a thin film transistor having excellent operating characteristics can be formed on a flexible or insulating substrate by using a metal oxide layer subjected to heat treatment after being deposited at a low temperature as an active layer of the thin film transistor, and damaging the substrate as well as lowering film quality. It is an object of the present invention to provide a metal oxide semiconductor thin film transistor manufacturing method capable of preventing a change.

Preparing a substrate according to the present invention, a metal oxide film on the substrate by a chemical vapor deposition at a deposition temperature of 20 to 150 degrees, and a metal comprising a step of performing a heat treatment process at a heat treatment temperature higher than the deposition temperature Provided are an oxide layer forming method.

The heat treatment temperature of the heat treatment step is 150 to 300 degrees, the heat treatment time is effective in the range of 2 to 30 seconds.

The heat treatment is performed by maintaining the same heat treatment temperature during the heat treatment time, or heat treatment by raising or lowering the heat treatment temperature according to the elapsed heat treatment time, or by heat treating the temperature in some sections of the heat treatment time higher than the temperature in the other sections. Alternatively, heating and cooling may be repeatedly performed a plurality of times during the heat treatment process, or the heat treatment may be performed by changing the heat treatment temperature a plurality of times to a first temperature and a second higher temperature.

It is preferable to use an insulating substrate or a flexible substrate as the substrate and to deposit the metal oxide film using a reaction gas containing a metal precursor and oxygen.

Depositing the metal oxide film and performing the heat treatment process may be performed continuously.

The method may further include preparing a substrate on which a gate electrode and a gate insulating film are formed, depositing a metal oxide film on the substrate by a chemical vapor deposition method at a deposition temperature on the gate insulating film in an upper region of the gate electrode, and depositing a metal oxide film on the substrate. A method of manufacturing a metal oxide semiconductor thin film transistor comprising performing a heat treatment process at a higher heat treatment temperature to form a metal oxide active layer and forming a source and a drain electrode on the metal oxide active layer.

It is effective that the deposition temperature is 20 to 150 degrees and the heat treatment temperature is 150 to 400 degrees.

In addition, forming a gate electrode and a gate insulating film on the substrate according to the present invention, forming a source and drain electrode, a part of which overlaps the gate electrode respectively on the gate insulating film, and chemical vapor deposition at a deposition temperature And depositing a metal oxide layer on the entire structure, and performing a heat treatment process at a heat treatment temperature higher than the deposition temperature to form a metal oxide active layer on the gate electrode and overlapping the source and drain electrodes. It provides a metal oxide semiconductor thin film transistor manufacturing method comprising the step.

It is effective that the deposition temperature is 20 to 150 degrees and the heat treatment temperature is 150 to 400 degrees.

In addition, forming a source and drain electrode on the substrate according to the present invention, by depositing a metal oxide film on the entire structure by a chemical vapor deposition method at a deposition temperature, performing a heat treatment process at a heat treatment temperature higher than the deposition temperature, Forming a metal oxide active layer overlapping the source and drain electrodes with a portion thereof; forming a gate insulating film on the at least metal oxide active layer; and between the source and drain electrodes on the gate insulating film above the metal oxide active layer. It provides a metal oxide semiconductor thin film transistor manufacturing method comprising the step of forming the gate electrode to be located in.

The deposition temperature is 20 to 150 degrees, the heat treatment temperature is preferably 150 to 300 degrees.

In addition, depositing a metal oxide film on the entire structure by a chemical vapor deposition method at a deposition temperature according to the present invention, and performing a heat treatment process at a heat treatment temperature higher than the deposition temperature to form a metal oxide active layer on a substrate, the at least Forming a source and a drain electrode on both edges of the metal oxide active layer, and sequentially forming a gate insulating film and a gate electrode on the metal oxide active layer between the at least source and drain electrodes. Provided is a method for manufacturing a transistor.

It is effective that the deposition temperature is 20 to 150 degrees and the heat treatment temperature is 150 to 300 degrees.

As described above, the present invention can prevent damage such as bending of the substrate during the deposition process by depositing a metal oxide film at low temperature, and increase the grain size and change the crystallinity of the low temperature metal oxide film through a subsequent rapid heat treatment process. The film quality of the oxide film can be increased.

In addition, the present invention can reduce substrate damage due to heat treatment through optimization of the temperature and time of the rapid heat treatment process, and the heat treatment method.

In addition, the present invention can reduce the productivity as well as improve the production yield by depositing the metal oxide film by chemical vapor deposition.

In addition, the present invention can be used as a channel layer of a thin film transistor having a metal oxide semiconductor film produced through low temperature deposition and heat treatment to improve the operating characteristics of the thin film transistor.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. Like numbers refer to like elements in the figures.

1 and 2 are cross-sectional views illustrating a method of forming a metal oxide film according to an embodiment of the present invention. 3 is a graph illustrating a temperature change of a metal oxide film forming process according to an exemplary embodiment.

Referring to FIGS. 1 and 2, the metal oxide forming method of the present exemplary embodiment may be formed by first depositing the metal oxide film 110 on the substrate 100 by chemical vapor deposition (CVD), that is, organic metal chemical vapor deposition (MOCVD) at a low deposition temperature. To be deposited on. Thereafter, the heat treatment process is performed at a high heat treatment temperature higher than the deposition temperature.

Here, the substrate 100 may be an insulating substrate (eg, glass, transparent plastic, acrylic, stainless coated with an insulating film) or a flexible substrate. Of course, a semiconductor wafer such as silicon may be used as the substrate.

In this case, the metal oxide film 110 formed may include at least one of Zn oxide, Sn oxide, In oxide, Cd oxide, Ga oxide, Al oxide, and ITO (Indium Tin Oxide). Alternatively, at least one of the compounds of the oxides (Zn, Sn, In, Ga, Cd, Al calculation products) or alloy forms thereof (binary, ternary, quaternary) may be used. In this embodiment, Zn-based oxide is used as the metal oxide film 110. Diethylzinc (DEZ) or dimethylzinc (Dimethylzinc; DMZ) may be used as the metal precursor for this purpose. In the following description, the ZnO film is formed of the metal oxide film 110.

First, as shown in FIGS. 1 and 3, the metal oxide film 110 is formed on the substrate 100 by chemical vapor deposition at a deposition temperature.

That is, a metal precursor, that is, at least one of DEZ and DMZ and a reaction gas are supplied to the substrate 100. As a result, the metal precursor and the reactant gas react to form the metal oxide layer 110 on the substrate 100. It is preferable to use an oxygen-containing gas as the reaction gas.

At this time, the deposition temperature is preferably 150 degrees or less. Preferably it is effective to carry out at a temperature of less than 100 degrees. As shown in FIG. 3, it is preferable to keep the deposition temperature constant during the deposition process of the metal oxide film 110. The deposition temperature refers to a process temperature for depositing the metal oxide film 110 and refers to a temperature inside the chamber.

Here, it is preferable that the range of vapor deposition temperature is 20-150 degree | times. Of course, it is more effective that the deposition temperature is in the range of 30 to 100 degrees. By maintaining the deposition temperature range as described above, it is possible to prevent damage to the substrate 100 such as deformation by depositing the metal oxide film 110. In this case, when the metal oxide film 110 is deposited at a temperature higher than the above range, the flexible substrate having a thin thickness may be damaged. When the metal oxide film 110 is deposited at a temperature lower than the above range, the deposition rate of the metal oxide film 110 may decrease rapidly. Therefore, it is preferable to deposit the metal oxide film 110 within the deposition temperature in the above range. In addition, in order to increase the deposition rate of the metal oxide film 110 while minimizing deformation of the substrate 100, it is preferable to maintain the deposition temperature in the range of 50 to 90 degrees.

As described above, in the present exemplary embodiment, the metal oxide layer 110 may be deposited by chemical vapor deposition, thereby increasing productivity and reducing production cost, compared to sputtering using a conventional target. In addition, a uniform metal oxide film 110 may be formed on the plurality of substrates 100.

Subsequently, as shown in FIGS. 2 and 3, a heat treatment process is performed on the metal oxide film 110 at a heat treatment temperature higher than the deposition temperature.

Through the heat treatment process, the film quality of the metal oxide film 110 may be improved. That is, the grain size and crystallinity of the low-temperature deposited metal oxide film 110 may be changed through a heat treatment process. Through this, a high quality metal oxide film 110 can be manufactured.

At this time, the heat treatment process is performed under process conditions that can minimize the thermal stress applied to the substrate 100. Since the heat treatment process is performed at a temperature higher than the temperature of the deposition process, the substrate 100 may be bent due to thermal stress unless the conditions of the heat treatment process are optimized.

For this purpose, the heat treatment process uses rapid heat treatment equipment that can raise the temperature instantaneously. This may cause a problem that the substrate 100 is heated to a high temperature during the heat treatment process due to a long heat treatment process time when the heat treatment temperature rises slowly. At this time, the temperature increase rate of the heat treatment equipment has a range of 100 to 400 degrees per second, it is effective that the temperature reduction rate also has a range of 50 to 300 degrees per second.

Through this, the metal oxide film 110 may be heat-treated at an instantaneously high temperature, and the temperature may be lowered before the substrate 100 is heated by the heat of the heat treatment process. Through this, thermal stress of the substrate 100 may be minimized.

In addition, the heat treatment temperature which is the temperature of the heat treatment process is preferably carried out in the range of 150 to 300 degrees. Here, when the temperature is lower than the temperature, the grain size and crystallinity of the metal oxide film 110 do not change or the degree of change thereof is insignificant. When the temperature is higher than the temperature, a thermal stress (heat burden) applied to the substrate 100 increases, thereby causing a problem that the substrate 100 is damaged.

And, the heat treatment process time is effective to perform within the range of 2 seconds to 30 minutes. At this time, when the process time is smaller than the change in the metal oxide film 110 by heat treatment does not occur. In addition, when larger than the time range, damage to the substrate 100 due to heat occurs.

That is, as shown in FIG. 3, the grain size of the metal oxide film 110 is increased by continuously heating the metal oxide film 110 at the same heat treatment temperature during the heat treatment process time, and the crystallinity of the metal oxide film 110 is increased. To change.

Of course, it is not limited to this, Various modifications are possible. That is, the heat treatment may be performed by varying the heat treatment temperature according to the process time.

4 to 8 are views showing a temperature change for the heat treatment process according to a modification of the embodiment.

First, as in the modification of FIG. 4, the heat treatment may be performed by increasing the heat treatment temperature according to the heat treatment time. In FIG. 4, the heat treatment temperature is sequentially increased (ie changed) twice, and heat treatment is performed using three different heat treatment temperatures. That is, the heat treatment is performed at the first temperature at the start of the heat treatment process, and then the heat treatment is performed within a second temperature range higher than the first temperature after a predetermined time. The heat treatment is performed at a third temperature higher than the second temperature for the remaining time. Of course, the present invention is not limited thereto, and the heat treatment may be performed by increasing the heat treatment temperature at least once. That is, the heat treatment may be performed at a number less or more than three different temperatures (ie, first to third temperatures).

Here, it is preferable that the average temperature of the changed temperatures in the heat treatment process is a value within the aforementioned heat treatment temperature range. Of course, the present invention is not limited thereto, and the changed temperature is preferably a value within the heat treatment temperature range.

At this time, the heat treatment time at each temperature is preferably the same. That is, the time of heat treatment at the first temperature and the time of heat treatment at the second temperature and the third temperature are the same. Of course, the present invention is not limited thereto, and the heat treatment time at each temperature may be different. At this time, various heat treatment times can be adjusted. However, it is effective that the time for heat treatment at the first temperature is longest and the time for heat treatment at the third temperature is shortest. This can increase the heat treatment time at low temperature and reduce the heat treatment time at high temperature, thereby reducing thermal stress (thermal damage) on the substrate 100 with respect to the heat treatment temperature.

In addition, as in the modification of FIG. 5, the heat treatment may be performed by lowering the heat treatment temperature step by step according to the heat treatment time. In FIG. 5, the heat treatment temperature is lowered (ie changed) three times in sequence to perform heat treatment using three different heat treatment temperatures. That is, the heat treatment is performed at the first temperature, which is the highest temperature at the beginning of the heat treatment process, and then the heat treatment is performed within a second temperature range lower than the first temperature after a predetermined time. The heat treatment is performed at a third temperature lower than the second temperature for the remaining time.

In addition, as in the modification of FIG. 6, the heat treatment may be performed by increasing the temperature in some sections higher than the temperature in the other sections. As shown in FIG. 6, the heat treatment is performed at the first temperature at the instant of starting the heat treatment process. Subsequently, in the high temperature heating section (P section in FIG. 6), the heat treatment is performed at a second temperature higher than the first temperature. After the high temperature section, heat treatment is performed again at the first temperature. Through this, the film quality of the metal oxide film 110 may be improved. That is, by providing a high temperature heating section in the middle of the heat treatment process, grain size of the metal oxide film 110 may be increased and crystallinity may be improved. As shown in FIG. 4, the average of the first temperature and the second temperature is preferably a value within the aforementioned heat treatment temperature range. Of course, the present invention is not limited thereto, and the changed temperature is preferably a value within the heat treatment temperature range. In addition, the high temperature heating section is preferably in the range of 10 to 50% of the entire heat treatment process section. Of course, the high temperature heating section is more preferably in the range of 15 to 40%. At this time, when the high temperature heating section is smaller than the above range, the grain size of the metal oxide film 110 does not increase as much as the target. In addition, when larger than the above range, the substrate 100 may be bent due to thermal stress.

In addition, as in the modification of FIG. 7, heating and cooling may be repeatedly performed during the heat treatment process. That is, the heating can be performed in a pulse type as shown in FIG. This is carried out alternately between heating and stopping heating, without continuously heating during the heat treatment process. This may be performed by repeatedly performing an operation of rapidly heating and rapidly cooling through a rapid heat treatment apparatus during the heat treatment process.

At this time, the width of the heating section and the cooling section is preferably the same.

Not limited to this, it is preferable that the width of the cooling section is longer than the width of the heating section. Through this, only the metal oxide layer 110 may be heated, and the substrate 100 may be prevented from being damaged by heat.

In addition, the sum of one heating section and one cooling section is preferably in the range of 0.1 to 50% of the entire heat treatment step. For example, when the time of the entire heat treatment process section is 10 seconds, the sum of one heating section and one cooling section is 0.01 to 5 seconds. More preferably, the sum of the one heating section and the one cooling section is effective in the range of 1 to 30%. As described above, the heating and cooling can be repeated to effectively heat only the metal oxide film 110, and damage to the substrate 100 due to the heat of the heat treatment process can be prevented. In addition, the present invention is not limited thereto, and the temperature of the heating section may be variously changed as in the modification of FIGS. 4 to 6.

In addition, as in the modification of FIG. 8, the first heating for heating to the first temperature and the second heating for heating to a second temperature lower than the first temperature may be repeated a plurality of times during the heat treatment process.

This is carried out by repeatedly performing the operation of rapidly heating to a first temperature through a rapid heat treatment apparatus and then heating to a second lower temperature during the heat treatment process.

As such, the grain size of the metal oxide film 110 can be increased and crystallinity can be improved by heating the metal oxide film 110 without causing a large temperature change.

As described above, the temperature in the heat treatment process may vary depending on the substrate used. This is because the deformation value of the substrate varies with temperature. In particular, in the case of depositing a metal oxide thin film on a flexible substrate (or a flexible insulating substrate) and performing heat treatment, as described above, it is effective to vary the temperature according to the flexible substrate.

For example, polycarbonate (PC) has a substrate deformation temperature of 215 degrees. Therefore, it is preferable to perform heat treatment at a lower temperature. That is, it is effective to heat-treat at a temperature of about 180 degrees. In addition, polyethersulfone (PES) has a deformation temperature of 223 degrees. Therefore, heat treatment at a temperature of about 180 degrees is effective. In addition, polyimide has a deformation temperature of 360 degrees. Therefore, heat treatment at about 180 or less is effective. Of course, the heat treatment may be performed at 200 degrees or less. Polynorbonene has a deformation temperature of 169 degrees. Therefore, it is effective to carry out the heat treatment at a temperature of 150 degrees or less. Also, the polyarylate has a deformation temperature of 325 degrees. Therefore, heat treatment at a temperature of 250 degrees or less is effective. In addition, polyetheretherketone (PEEK) has a deformation temperature of 140 degrees, but it is possible to perform heat treatment at a temperature of 250 or less. In addition, polyetherimide (PEI) has a deformation temperature of 215 degrees. Therefore, heat treatment at 200 degrees or less is effective. In addition, polyethylenenaphthalate (PEN) has a deformation temperature of 120 degrees, but it is effective to perform heat treatment at a temperature of 150 degrees or less. In addition, the polyethylene terephthalate (poly (ethyl ene terephthalte); PET) is preferably carried out a heat treatment at a temperature of 130 degrees or less.

In addition, if stainless steel is used as the substrate, the heat treatment temperature may be increased to a range of 500 degrees or less. Of course, when using an organic substrate, since the strain temperature is 480 degrees, the heat treatment can be performed in the range of about 400 degrees or less.

In the following, changes in thin film characteristics before and after heat treatment of the metal oxide film 110 fabricated according to the present embodiment will be described using experimental results.

9 is a SEM (Scanning Electron Micorscope) photograph of a metal oxide film formed according to an embodiment. 10 illustrates X-ray diffraction (XRD) measurement results of a metal oxide film formed according to an embodiment.

In this experiment, the metal oxide film 110 was deposited by CVD deposition at 100 degrees, and rapidly heated at a temperature of about 250 degrees for 20 minutes.

9A is a SEM photograph of the metal oxide film 110 before heat treatment. That is, the metal oxide film 110 is deposited on the substrate 100 manufactured by CVD at a temperature of 100 degrees, and then the photographed metal oxide film 110 is photographed using SEM equipment. FIG. 9B is a SEM photograph of the metal oxide film 110 after heat treatment. That is, after performing the heat treatment method within the range that does not damage the substrate 100, the deposited metal oxide film 110 is a photograph of the heat-treated metal oxide film 110 by using the SEM equipment.

Accordingly, as shown in the photograph of FIG. 9, it can be seen that the grain size of the metal oxide film 110 before and after the heat treatment (FIG. 9A) and after the heat treatment (FIG. 9B) changes. That is, it can be seen that the grain size of the metal oxide film 110 after the heat treatment is greatly increased.

In addition, when the degree of crystallization is examined through XRD measurement as shown in FIG. 10, it can be seen that only the peak 002 of the single crystal form is grown before the heat treatment. However, the metal oxide film 110 after the heat treatment showed a form in which the 002 peak was lowered and 100 peaks and 101 peaks were grown. Therefore, it can be seen that the crystallinity of the low-temperature deposited metal oxide film 110 is changed through heat treatment.

Hereinafter, a method of manufacturing a thin film transistor using the metal oxide semiconductor fabricated by the above method as an active layer will be described.

11 is a view for explaining a method of manufacturing a metal oxide semiconductor thin film transistor according to the first embodiment of the present invention.

First, as shown in FIG. 11A, a gate electrode 210 and a gate insulating film 220 are formed on a substrate 200.

In the present exemplary embodiment, a transparent substrate such as glass, plastic, and acrylic, which are insulating substrates, or a stainless substrate coated with an insulating layer may be used as the substrate 200. Of course, a flexible substrate may be used as the substrate 200.

First, a first conductive layer for a gate electrode is formed on the substrate 200 through a deposition method using a CVD method, a PVD method, a sputtering method, or the like. At this time, it is preferable to use Cr, Mo, Al, Cu, Nd, W, Ti, Au, Ta, and a transparent conductive film containing ITO and ZnO and the alloy metals thereof as the first conductive layer. Of course, the first conductive layer may be manufactured in a plurality of layers in consideration of the conductive characteristics and the resistance characteristics. Subsequently, a photosensitive film is coated on the first conductive layer, and then a lithography process using a first mask is performed to form a first photosensitive film mask pattern. An etching process using the first photoresist mask pattern as an etching mask is performed to form the gate electrode 210. Subsequently, a predetermined strip process is performed to remove the first photoresist mask pattern. At this time, although not shown, it is preferable that the gate line (or word line, first wiring) connected to the gate electrode 210 is formed together according to an element formed on the substrate.

Of course, the gate electrode 210 may be directly formed on the substrate 200 through sputtering using a shadow mask. In addition, the gate electrode 210 may be formed through a printing technique.

Subsequently, a gate insulating layer 220 is formed on the substrate 200 on which the gate electrode 210 is formed. Here, it is preferable to use an inorganic insulating material including an oxide film and / or a nitride film as the gate insulating film 220. Of course, the present invention is not limited thereto, and an organic insulating material may be used.

As shown in FIG. 11B, a metal oxide semiconductor film 231 is formed on the gate insulating film 220.

The metal oxide semiconductor film 231 is manufactured by a chemical vapor deposition method using a metal precursor and a reactant gas as in the foregoing manufacturing method. Subsequently, the metal oxide semiconductor film 231 is heat treated through a heat treatment process.

At this time, since the metal oxide semiconductor film 231 is formed on the gate insulating film 220 instead of the insulating substrate 200, the deposition maximum temperature of the metal oxide semiconductor film 231 is reduced by about 2 to 40% compared to the substrate 200. Can be. This is because the metal oxide semiconductor film 231 grows better on the gate insulating film 220 composed of an oxide film and / or a nitride film than the glass, plastic, or flexible substrate. Therefore, the metal oxide semiconductor film 231 may be deposited at a temperature between 100 degrees and below at room temperature.

In this embodiment, the maximum temperature of the heat treatment process may also be increased by 1 to 50%. The gate insulating film 220 composed of an oxide film and a nitride film has stable characteristics without thermal changes within the aforementioned heat treatment temperature range. Therefore, the temperature of the heat treatment process can be carried out in the range of 150 to 400 degrees.

Although not shown, an ohmic contact layer for reducing contact surface resistance and reducing leakage current may be further formed on the metal oxide semiconductor film 231.

As shown in FIG. 11C, the metal oxide semiconductor layer 231 is etched to form the metal oxide active layer 230, and the source and drain electrodes 250 and 260 are formed on the metal oxide active layer 230.

To this end, first, a photosensitive film is coated on the metal oxide semiconductor film 231. Subsequently, a lithography process using the second mask is performed to form a second photosensitive film mask pattern. The second photoresist mask pattern is positioned on the metal oxide semiconductor film 231 above the gate electrode 210. That is, the second photoresist mask pattern is manufactured to shield the metal oxide semiconductor film 231 in the upper region of the gate electrode 210. An etching process using the second photoresist mask pattern as an etching mask is performed to remove the exposed metal oxide semiconductor film 231 to form the metal oxide active layer 230 in the upper region of the gate electrode 210. Subsequently, a predetermined strip process is performed to remove the second photosensitive film mask pattern.

Thereafter, a second conductive layer is formed on the gate insulating layer 220 on the metal oxide active layer 230. At this time, it is preferable to use Cr, Mo, Al, Cu, Nd, W, Ti, Au, Ta, and a transparent conductive film containing ITO and ZnO and alloy metals thereof as the second conductive layer. Of course, the second conductive layer may be manufactured in a plurality of layers in consideration of the conductive characteristics and the resistance characteristics. Subsequently, after the photosensitive film is coated on the second conductive layer, a lithography process using a third mask is performed to form a third photoresist mask pattern. An etching process using the third photoresist mask pattern as an etching mask is performed to form source and drain electrodes 250 and 260.

Subsequently, a predetermined strip process is performed to remove the third photoresist mask pattern. In this case, although not shown, a source line (or data line) connected to the source electrode 250 and a drain line connected to the drain electrode 260 may be formed together according to the manufactured device.

Through the above-described process, a thin film transistor having a metal oxide active layer 230 deposited at a low temperature and having an improved film quality through heat treatment may be manufactured. In the above description, the thin film transistor is manufactured through three masking operations (photoresist coating / lithography / removal film removal), but the present invention is not limited thereto, and the thin film transistor may be manufactured through fewer or more masking operations.

As such, the reaction rate of the thin film transistor may be improved by fabricating the metal oxide active layer 230 having improved film quality through heat treatment. In addition, the metal oxide active layer 230 may be fabricated at low temperature by chemical vapor deposition, and the manufacturing process of the metal oxide thin film may be simplified, and the characteristics of the thin film may be prevented from changing. This increases productivity for thin film transistors and reduces costs with water.

The thin film transistor of the present embodiment described above may be used as a switching element of a display panel. When used as a switching element of a display panel, a passivation film is formed on the entire surface of the substrate 200 including the thin film transistor, and a passivation film is formed on the passivation film. Then, a pixel electrode is formed on the protective film. In this case, the pixel electrode is connected to the drain electrode 260 through a through hole passing through the passivation layer and the passivation layer.

The thin film transistor manufacturing method of this embodiment is not limited to the above-described embodiment, and various modifications are possible. The description overlapping with the above-described embodiment will be omitted. The description of the embodiments described below and the description of the above-described embodiments may be applied to each other.

12 is a view for explaining a method of manufacturing a metal oxide semiconductor thin film transistor according to a second embodiment of the present invention.

As shown in FIG. 12A, a gate electrode 210 is formed on the substrate 200, and a gate insulating layer 220 covering the gate electrode 210 is formed. Source and drain electrodes 250 and 260 are formed on the gate insulating layer 220 to partially overlap the gate electrode 210.

As shown in FIG. 12B, the metal oxide active layer 230 overlapping the source and drain electrodes 250 and 260 may be formed on the gate electrode 210.

Here, in order to form the metal oxide active layer 230, first, a metal oxide film is deposited at a low temperature (ie, a temperature of about 100 degrees or less) and heat-treated at a higher temperature to form a metal oxide semiconductor film. Subsequently, the metal oxide semiconductor layer is etched using the mask pattern to form a metal oxide active layer 230 that serves as a channel between the gate electrode 210 and the source and drain electrodes 250 and 260.

Of course, the present embodiment is not limited thereto, and a metal oxide layer may be formed at a low temperature, etched to form a metal oxide active layer 230, and then a heat treatment process may be performed. Through this, damage to the substrate 200 by the heat treatment process can be suppressed.

13 is a view for explaining a method of manufacturing a metal oxide semiconductor thin film transistor according to a third embodiment of the present invention.

As shown in FIG. 13A, source and drain electrodes 250 and 260 are formed on the substrate 200. The metal oxide semiconductor film 231 is formed on the entire surface of the substrate 200.

The metal oxide semiconductor film 231 is deposited at low temperature by chemical vapor deposition. Then, a heat treatment step for heating the metal oxide semiconductor film 231 is performed.

As shown in FIG. 13B, the metal oxide semiconductor layer 231 is etched to form a metal oxide active layer 230 in which part of the source and drain electrodes 250 and 260 overlap with each other.

Subsequently, the gate insulating film 220 is formed on the entire structure. Thereafter, the gate electrode 210 is formed in the upper region of the metal oxide active layer 230 to be positioned between the source and drain electrodes 250 and 260.

In the present embodiment, the heat treatment process may be performed after the metal oxide active layer 230 is formed as in the previous embodiment.

14 is a view for explaining a method of manufacturing a metal oxide semiconductor thin film transistor according to a fourth embodiment of the present invention.

As shown in FIG. 14A, a metal oxide semiconductor film 231 is formed on the substrate 200.

As described above, the metal oxide semiconductor film 231 is formed by depositing a metal oxide on the substrate 200 at a low temperature by chemical vapor deposition, and heat-treating it to a temperature higher than the deposition temperature.

As shown in FIG. 14B, the metal oxide semiconductor layer 231 is etched using a mask to form an island-shaped metal oxide active layer 230. Subsequently, source and drain electrodes 250 and 260 are formed in the edge region of the metal oxide active layer 230, and the gate insulating layer 220 and the gate electrode 210 are formed in the central region.

In this case, a portion of the source and drain electrodes 250 and 260 may overlap the metal oxide active layer 230. In addition, the gate insulating layer 220 may be formed in regions above the source and drain electrodes 250 and 260.

As described above, a thin film transistor may be manufactured to improve operating characteristics of the thin film transistor. Furthermore, the film quality performance of the metal oxide active layer 220 used as the channel layer may be increased by performing a heat treatment process when fabricating the metal oxide active layer 220. As a result, the mobility of the carrier in the channel layer is increased, thereby improving operating characteristics of the thin film transistor.

15 is a graph for explaining operating characteristics of a thin film transistor before and after heat treatment of a channel layer.

FIG. 15A is a graph (IV curve) showing an operating characteristic of a thin film transistor using a metal oxide active layer 220 which is deposited at a low temperature and not subjected to heat treatment as a channel layer, and FIG. 15B is a channel. It is a graph showing the operating characteristics of the thin film transistor using the metal oxide active layer 220 which is deposited at a low temperature as a layer and subjected to heat treatment. 15C is a table showing changes in grain size of the channel layer and changes in characteristics of the thin film transistor.

15A and 15B, the drain current I _D increases as the gate voltage V _G increases. However, it can be seen that the magnitude of the drain current flowing at the same gate voltage is higher in FIG. This shows that the mobility in FIG. 15B is higher than that in FIG. 15A. In this calculation, the mobility of the channel region of the thin film transistor of FIG. 15A is 0.113 cm 2 / Vs, but the mobility of the channel region of the thin film transistor of FIG. 15B is 0.645 cm 2 / Vs.

When the heat treatment is performed as shown in FIG. 15C, the grain size of the channel layer is increased from 20 nm to 40 nm, and the threshold voltage is also lowered from 18.9 V to 13.4 V. FIG. On current was also 2.6E-5A before heat treatment, but on current after heat treatment was improved to 2.2E-4.

As such, when the metal oxide active layer 220 which is formed at a low temperature as the channel layer of the thin film transistor and undergoes the heat treatment process is used, the operating characteristics of the thin film transistor may be improved.

The present invention is not limited to the above-described embodiments, but may be implemented in various forms. In other words, the above embodiments are provided to complete the disclosure of the present invention and to fully inform those skilled in the art of the scope of the present invention, and the scope of the present invention should be understood by the claims of the present application. do.

1 and 2 are cross-sectional views for explaining a metal oxide film forming method according to an embodiment of the present invention.

3 is a graph showing a temperature change in a metal oxide film forming process according to an embodiment.

4 to 8 is a view showing a temperature change for the heat treatment process according to a modification of one embodiment.

9 is a SEM (Scanning Electron Micorscope) photo of the metal oxide film formed according to one embodiment.

10 is an X-ray diffraction (XRD) measurement result of the metal oxide film formed according to one embodiment.

11 is a view for explaining a method for manufacturing a metal oxide semiconductor thin film transistor according to the first embodiment of the present invention.

12 is a view for explaining a metal oxide semiconductor thin film transistor manufacturing method according to a second embodiment of the present invention.

13 is a view for explaining a metal oxide semiconductor thin film transistor manufacturing method according to a third embodiment of the present invention.

14 is a view for explaining a metal oxide semiconductor thin film transistor manufacturing method according to a fourth embodiment of the present invention.

15 is a graph for explaining operating characteristics of a thin film transistor before and after heat treatment of a channel layer.

<Explanation of symbols for major symbols in the drawings>

100, 200: substrate 110: metal oxide layer

210: gate electrode 220: gate insulating film

230 metal oxide active layer 231 metal oxide semiconductor film

Claims (13)

Preparing a substrate; Depositing a metal oxide film on the substrate by chemical vapor deposition at a deposition temperature of 20 to 150 degrees; And The metal oxide layer forming method comprising the step of performing a heat treatment at a heat treatment temperature higher than the deposition temperature. The method according to claim 1, The heat treatment temperature of the heat treatment step is 150 to 300 degrees, the heat treatment time is in the range of 2 to 30 seconds metal oxide layer forming method. The method according to claim 1, The heat treatment is performed by maintaining the same heat treatment temperature during the heat treatment time, or heat treatment by raising or lowering the heat treatment temperature according to the elapsed heat treatment time, or by heat treating the temperature in some sections of the heat treatment time higher than the temperature in the other sections. Or heat-treatment by repeatedly heating and cooling a plurality of times during the heat-treatment process, or changing the heat-treatment temperature a plurality of times to a first temperature and a second higher temperature. The method according to claim 1, Using an insulating substrate or a flexible substrate as the substrate, A metal oxide layer forming method for depositing the metal oxide film using a reaction gas containing a metal precursor and oxygen. The method according to claim 1, And depositing the metal oxide film and performing the heat treatment process. Providing a substrate on which a gate electrode and a gate insulating film are formed; Depositing a metal oxide film on the substrate by a chemical vapor deposition at a deposition temperature on the gate insulating layer in the upper region of the gate electrode, and performing a heat treatment at a heat treatment temperature higher than the deposition temperature to form a metal oxide active layer; And Forming a source and a drain electrode on the metal oxide active layer. The method according to claim 6, The deposition temperature is 20 to 150 degrees, the heat treatment temperature is 150 to 400 degrees metal oxide semiconductor thin film transistor manufacturing method. Forming a gate electrode and a gate insulating film on the substrate; Forming a source and a drain electrode on a portion of the gate insulating layer, the portions of which overlap each of the gate electrodes; A metal oxide film is deposited on the entire structure by a chemical vapor deposition method at a deposition temperature, and a heat treatment process is performed at a heat treatment temperature higher than the deposition temperature. The metal is positioned above the gate electrode and overlaps the source and drain electrodes with a portion thereof. A metal oxide semiconductor thin film transistor manufacturing method comprising the step of forming an oxide active layer. The method according to claim 8, The deposition temperature is 20 to 150 degrees, the heat treatment temperature is 150 to 400 degrees metal oxide semiconductor thin film transistor manufacturing method. Forming source and drain electrodes on the substrate; Depositing a metal oxide film on the entire structure by chemical vapor deposition at a deposition temperature and performing a heat treatment at a heat treatment temperature higher than the deposition temperature to form a metal oxide active layer overlapping the source and drain electrodes; Forming a gate insulating film on the at least metal oxide active layer; And Forming the gate electrode on the gate insulating layer above the metal oxide active layer so as to be positioned between the source and drain electrodes. The method according to claim 10, The deposition temperature is 20 to 150 degrees, the heat treatment temperature is 150 to 300 degrees metal oxide semiconductor thin film transistor manufacturing method. Depositing a metal oxide film on the entire structure by chemical vapor deposition at a deposition temperature, and performing a heat treatment process at a heat treatment temperature higher than the deposition temperature to form a metal oxide active layer on the substrate; Forming source and drain electrodes on at least both edges of the metal oxide active layer; And sequentially forming a gate insulating film and a gate electrode on the metal oxide active layer between the at least source and drain electrodes. The method according to claim 12, The deposition temperature is 20 to 150 degrees, the heat treatment temperature is 150 to 300 degrees metal oxide semiconductor thin film transistor manufacturing method.

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