CN1315156C - Manufacturing method of polysilicon thin film - Google Patents

Abstract

A method for manufacturing a polycrystalline silicon film comprises sequentially forming an insulating layer, a first amorphous silicon layer and a top cover layer on a substrate, and performing a first laser annealing process to form a first polycrystalline silicon layer with at least one hole on the first amorphous silicon layer; removing the top cover layer and the partial insulating layer in the hole, forming a first opening in the insulating layer, and forming a second opening by the hole and the first opening; then forming a second amorphous silicon layer in the second opening and on the surface of the first polycrystalline silicon layer, wherein the second amorphous silicon layer is provided with a lower recess in the second opening; and finally, carrying out a second laser annealing process, and carrying out a crystal growth step by taking the lower concave part as a crystallization position so that a second polycrystalline silicon layer is formed by the second amorphous silicon layer and the first polycrystalline silicon layer. The invention can form the hole with the size smaller than the deep sub-micron without complex processes such as exposure, photoetching, forming a layer of deposition layer and the like; in addition, without the need of precise process condition control, the holes with the size suitable for the crystallization of the polysilicon film can be easily formed, and the process margin is larger.

Description

Manufacturing method of polysilicon thin film

technical field

The invention relates to a method for manufacturing a thin film transistor liquid crystal display (TFT-LCD) in the field of semiconductor devices, in particular to a method for manufacturing a polysilicon film of a thin film transistor array in a thin film transistor (transistor) liquid crystal display.

Background technique

Generally, active array liquid crystal displays can be divided into polysilicon thin-film transistors (transistors) and amorphous silicon thin-film transistors (transistors) due to their materials. Among them, polysilicon thin-film transistors can provide higher performance than amorphous silicon thin-film transistors because they can integrate driving circuits. Transistors have a high aperture ratio and lower costs, and another reason why polysilicon thin film transistor technology is highly praised is that polysilicon thin film transistors can greatly reduce the size of components to achieve high resolution. Generally, polysilicon thin film transistor liquid crystal displays must have Low-temperature manufacturing technology (about 450 to 550 degrees Celsius), low-temperature film-forming technology of high-quality gate insulating film, and large-area ion implantation technology are three elements.

Based on the consideration of the price of the glass substrate, the growth of the thin film is carried out in a low temperature state, so the introduction of the solid phase crystallization method (Solid Phase Crystallization, SPC) was first introduced, but the reaction temperature is still high, the reaction temperature is about 600 degrees and The crystallinity is poor, and then, excimer laser (laser, Excimer Laser) is developed to apply excimer laser (laser, Excimer Laser) crystallization (Excimer Laser Crystallization, ELC) or excimer laser (laser ) annealing (Excimer Laser Annealing, ELA) process, by using a laser to scan the amorphous silicon film to melt it, and then recrystallize it into a polysilicon film.

Since the excimer laser crystallization process has the ability to reduce the process temperature to less than 450 degrees Celsius, and the polysilicon film formed by the laser crystallization method has higher electron mobility and lower leakage current than the solid phase crystallization method, it can The use of a lower-priced glass substrate further reduces the cost of the process and obtains better characteristics of the thin film transistor component.

Please refer to FIG. 1A to FIG. 1D , which are schematic diagrams of the manufacturing process of a known polysilicon thin film.

First, please refer to FIG. 1A, the prior known method of manufacturing a polysilicon thin film is to provide a substrate 100, then form an insulating layer 102 on the substrate 100, and then, by photolithography etching technology, insulator An opening 104 is formed in the layer. Since there is no deep sub-micrometer (sub-micrometer) technology available in the current photolithography technology in the field of thin film transistors, the critical dimension of the formed opening 104 is about 1 micron. For the critical crystal size, the opening The size of 104 is still too large, which is not conducive to the crystallization of the polysilicon film.

In order to overcome this problem, as shown in FIG. 1B , an insulating layer 106 is formed on the insulating layer 102, and by depositing the insulating layer 106, the opening 104 formed by the insulating layer 102 is narrowed to become an opening 108, so as to be able to The size suitable for polysilicon thin film crystallization process.

Next, as shown in FIG. 1C, an amorphous silicon layer 110 is formed on the insulating layer 106 and in the opening 108, and the amorphous silicon layer 110 is irradiated with an excimer laser 112 of sufficient energy, so that the amorphous silicon layer 110 melted into liquid silicon.

Finally, as shown in FIG. 1D, the molten liquid silicon crystallizes with the opening 108 as the crystallization site, so that the amorphous silicon layer 110 becomes a polysilicon layer 114, which is used for the source/drain region of the thin film transistor. and the channel area.

Yet, there is following problem in the manufacturing method of above-mentioned existing polysilicon thin film:

In the above-mentioned process, a photomask is required to form the opening 104, and a second layer of insulating layer 106 must be deposited after forming the opening 104 to adjust the size of the opening. The process is not only complicated, but also leads to a decrease in production capacity.

Moreover, by depositing the second layer of insulating layer 106 to adjust the size of the opening 108, if all the openings 108 on the substrate are to be of appropriate size, in fact, quite precise process condition control is required, so that the inventive process The margin becomes very small.

It can be seen that the above-mentioned existing polysilicon thin film manufacturing method still has many defects, and needs to be further improved urgently. In order to solve the defects of the existing polysilicon thin film manufacturing methods, relevant manufacturers have tried their best to find a solution, but no suitable design has been developed for a long time, and this is obviously a problem that the relevant industry is eager to solve.

In view of the defects in the above-mentioned existing manufacturing methods of polysilicon thin films, the inventor actively researches and innovates based on years of rich practical experience and professional knowledge engaged in the design and manufacture of such products, in order to create a new manufacturing method of polysilicon thin films , can improve the general existing polysilicon film manufacturing method, making it more practical. Through continuous research, design, and after repeated trial samples and improvements, the present invention with practical value is finally created.

Contents of the invention

The main purpose of the present invention is to overcome the defects of the existing polysilicon thin film manufacturing method and provide a new polysilicon thin film manufacturing method. The main technical problem to be solved is to make it unnecessary Forming a complex process such as a deposition layer can form pores smaller than sub-micron in size.

Another object of the present invention is to provide a method for manufacturing a polysilicon film. The technical problem to be solved is to make it easy to form holes (openings) with sizes suitable for polysilicon film crystallization without precise process condition control. ), and can have a larger process margin.

The purpose of the present invention and the solution to its main technical problems are achieved by adopting the following technical solutions. A method for manufacturing a polysilicon film according to the present invention at least includes the following steps: providing a substrate; sequentially forming an insulating layer, a first amorphous silicon layer and a top cover layer on the substrate; performing a a first excimer laser process, so that the first amorphous silicon layer forms a first polysilicon layer having at least one hole; removing the top cover layer; removing part of the insulation in the hole with a warm etching method layer, to form a first opening in the insulating layer, and the hole and the first opening form a second opening; a second amorphous silicon layer is formed in the second opening and on the surface of the first polysilicon layer silicon layer, wherein the second amorphous silicon layer has a depression at the position of the second opening; and performing a second excimer laser process, using the unmelted second amorphous silicon layer at the bottom of the second opening as In the crystallization position, the step of crystallization growth is performed so that the second amorphous silicon layer and the first polysilicon layer form a second polysilicon layer.

The purpose of the present invention and the solution to its technical problems can also be further realized by adopting the following technical measures.

In the aforementioned method for manufacturing a polysilicon film, the material of the top cover layer includes silicon dioxide.

In the aforementioned manufacturing method of the polysilicon film, the wet etching method for removing part of the insulating layer in the hole includes the wet etching method using hydrofluoric acid.

In the aforementioned method of manufacturing a polysilicon thin film, the diameter of the second opening is less than 1 micron.

The purpose of the present invention and its main technical problems are solved by adopting the following technical solutions. A method for manufacturing a polysilicon film according to the present invention at least includes the following steps: providing a substrate; sequentially forming an insulating layer, a first amorphous silicon layer and a top cover layer on the substrate; performing a a first excimer laser process, so that the first amorphous silicon layer forms a first polysilicon layer having at least one hole; removing the top cover layer; removing part of the insulating layer in the hole by wet etching , to form a first opening in the insulating layer, and the hole and the first opening form a second opening; a dielectric layer is formed in the second opening and on the surface of the first polysilicon layer, wherein The dielectric layer has a depression in the second opening; forming a second amorphous silicon layer on the dielectric layer; and performing a second excimer laser process, using the depression as a crystallization site, performing The step of crystallization growth makes the second amorphous silicon layer form a second polysilicon layer.

The purpose of the present invention and the solution to its technical problems can also be further realized by adopting the following technical measures.

In the aforementioned method for manufacturing a polysilicon film, the material of the top cover layer includes silicon dioxide.

In the aforementioned manufacturing method of the polysilicon film, the wet etching method for removing part of the insulating layer in the hole includes the wet etching method using hydrofluoric acid.

In the aforementioned method of manufacturing a polysilicon film, the material of the dielectric layer includes silicon dioxide.

In the aforementioned method of manufacturing a polysilicon thin film, the diameter of the second opening is less than 1 micron.

The purpose of the present invention and its main technical problems are solved by adopting the following technical solutions. According to a method for manufacturing a polysilicon thin film proposed by the present invention, it at least includes the following steps: providing a substrate; sequentially forming an insulating layer, a first amorphous silicon layer and a top cover layer on the substrate; A first excimer laser process, so that the first amorphous silicon layer forms a first polysilicon layer with at least a first hole; remove the top cover layer; remove the hole in the hole by wet etching A part of the insulating layer is used to form a first opening in the insulating layer, and the first hole and the first opening form a second opening; a hole is formed in the second opening and on the surface of the first polysilicon layer. a dielectric layer, wherein there is a second hole in the dielectric layer at the second opening; a second amorphous silicon layer is formed on the dielectric layer; and a second excimer laser process is performed, wherein the The temperature of the second amorphous silicon layer on the second hole is higher than that of other parts of the second amorphous silicon layer, and crystallizes and grows so that the second amorphous silicon layer forms a second polysilicon layer.

The purpose of the present invention and the solution to its technical problems can also be further realized by adopting the following technical measures.

In the aforementioned method for manufacturing a polysilicon film, the material of the top cover layer includes silicon dioxide.

In the aforementioned manufacturing method of the polysilicon film, the wet etching method for removing part of the insulating layer in the hole includes the wet etching method using hydrofluoric acid.

In the aforementioned method of manufacturing a polysilicon film, the material of the dielectric layer includes silicon dioxide.

In the aforementioned method of manufacturing a polysilicon thin film, the diameter of the second opening is less than 1 micron.

Compared with the prior art, the present invention has obvious advantages and beneficial effects. As can be seen from the above technical solutions, in order to achieve the aforementioned object of the invention, the main technical contents of the present invention are as follows:

The invention proposes a method for manufacturing a polysilicon thin film. The method is to sequentially form an insulating layer, a first amorphous silicon layer and a top cover layer on a substrate, and then perform a first laser annealing process to make the first amorphous silicon The layer forms a first polysilicon layer having at least one hole. Then, the top cover layer is removed, and part of the insulating layer in the hole is removed to form a first opening in the insulating layer, and the hole and the first opening form a second opening. Then, a second amorphous silicon layer is formed in the second opening and on the surface of the first polysilicon layer, wherein the second amorphous silicon layer has a recess in the second opening. Finally, the second laser annealing process is carried out, and the second amorphous silicon layer that is not melted at the bottom of the second opening is used as the crystallization position to carry out the step of crystal growth, so that the second amorphous silicon layer and the first polysilicon layer form a second polysilicon layer.

The present invention also proposes another method for manufacturing a polysilicon thin film. The method is to sequentially form an insulating layer, a first amorphous silicon layer, and a top cover layer on a substrate, and then perform a first laser annealing process to make the first amorphous silicon film The crystalline silicon layer forms a first polysilicon layer having at least one hole. Then, the top cover layer is removed, and part of the insulating layer in the hole is removed to form a first opening in the insulating layer, and the hole and the first opening form a second opening. Then, a dielectric layer is formed in the second opening and on the surface of the first polysilicon layer, and a second amorphous silicon layer is formed on the dielectric layer, wherein the second amorphous silicon layer has a lower layer in the second opening. recess. Finally, the second laser annealing process is carried out, and the step of crystallization growth is carried out with the lower recess as the crystallization position, so that the second amorphous silicon layer forms the second polysilicon layer.

The present invention also proposes another method for manufacturing a polysilicon thin film. The method is to sequentially form an insulating layer, a first amorphous silicon layer, and a top cover layer on a substrate, and then perform a first laser annealing process to make the first amorphous silicon film The crystalline silicon layer forms a first polysilicon layer having at least one first hole. Next, the top cover layer is removed, and part of the insulating layer in the first hole is removed to form a first opening in the insulating layer, and the first hole and the first opening form a second opening. Then, a dielectric layer is formed in the second opening and on the surface of the first polysilicon layer, wherein a second hole is formed in the dielectric layer of the second opening, and then a second amorphous silicon layer is formed on the dielectric layer . Finally, the second laser annealing process is carried out, wherein the temperature of the second amorphous silicon layer above the second hole is higher than that of the second amorphous silicon layer in other parts, prolonging the time required for the crystallization of liquid silicon, so that the second amorphous silicon layer The crystalline silicon layer is crystallized and grown to form a second polysilicon layer.

By means of the above technical solution, the method for manufacturing the polysilicon thin film of the present invention has at least the following advantages:

1. The present invention forms a top cover layer on the amorphous silicon layer, and performs a laser annealing process to crystallize the amorphous silicon layer into a polysilicon layer, that is, it is possible to form in the polysilicon layer and even the insulating layer the size of which is less than sub-micron. hole. Therefore, there is no need to perform complicated processes such as exposure, photolithography, and forming a deposition layer, and the production capacity can be increased.

2. The present invention does not require precise control of process conditions such as the formation of the top cover layer and the first laser annealing process, that is, holes with a size smaller than sub-micron in depth can be formed in the polysilicon layer or even the insulating layer as the crystallization site, so the present invention The invention can have a large process margin.

3. In the process of forming the dielectric layer of the present invention, even if the step coverage of the dielectric layer is poor and there are holes in the dielectric layer, the present invention can still carry out the crystallization growth process of the polysilicon film to form a component with good The characteristic polysilicon thin film can also make the present invention have a higher process margin.

To sum up, the manufacturing method of the special polysilicon thin film of the present invention does not need to perform complicated processes such as exposure, photolithography, and forming a layer of deposition layer, that is, it can form holes with a size smaller than sub-micron; in addition, it does not require precision Controlling the process conditions, that is, holes (openings) with a size suitable for crystallization of polysilicon thin films can be easily formed, and a large process margin can be obtained. It has the above-mentioned many advantages and practical value, it is indeed innovative in the manufacturing method, and has made great progress in technology, and has produced easy-to-use and practical effects, and has extensive industrial application value, so it is more suitable for practical use , Sincerely a novel, progressive and practical new design.

The above description is only an overview of the technical solutions of the present invention. In order to understand the technical means of the present invention more clearly and implement them according to the contents of the description, the preferred embodiments of the present invention and accompanying drawings are described in detail below.

Description of drawings

1A to 1D are schematic diagrams of the manufacturing process of the known polysilicon thin film

2A to 2E are schematic cross-sectional process diagrams of a manufacturing method for forming a polysilicon film according to a first embodiment of the present invention.

3A to 3F are schematic cross-sectional process diagrams of a method for manufacturing a polysilicon thin film according to a second embodiment of the present invention.

4A to 4F are schematic cross-sectional process diagrams of a method for manufacturing a polysilicon thin film according to a third embodiment of the present invention.

100, 200: substrate 300, 400: substrate

102, 106, 202: insulating layer 302, 402: insulating layer

104, 108, 214, 216: opening 314, 316, 414, 416: opening

110, 204, 218, 304: amorphous silicon layer 318, 404, 418: amorphous silicon layer

112: excimer laser (laser) 114, 210, 224, 310: polysilicon layer

324, 410, 424: polysilicon layer 206, 306, 406: top cover layer

208, 308, 408: the first laser annealing process 212, 312, 412, 420: holes

220, 320: The concave place 222, 322: The second laser annealing process

422: Second laser annealing process 317, 417: Dielectric layer

226, 326, 426: Arrows

Detailed ways

The specific manufacturing method, steps, features and effects of the manufacturing method of the polysilicon thin film according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

first embodiment

Please refer to FIG. 2A to FIG. 2E , which are schematic cross-sectional process diagrams of a manufacturing method for forming a polysilicon film according to a first embodiment of the present invention.

First, please refer to FIG. 2A. The method for manufacturing a polysilicon thin film according to a preferred embodiment of the present invention is to provide a substrate 200, which is, for example, a silicon wafer, a glass substrate or a plastic substrate. An insulating layer 202, the material of the insulating layer 202 is, for example, silicon dioxide, and the method of formation is, for example, low pressure chemical vapor deposition (Low Pressure Chemical Vapor Deposition, LPCVD) method, plasma enhanced chemical vapor deposition (Plasma Enhanced Chemical VaporDeposition, A silicon dioxide layer is formed on the substrate 200 by a PECVD method or a sputtering (Sputter) method. Next, an amorphous silicon layer 204 is formed on the insulating layer 202. The amorphous silicon layer 204 is formed by, for example, low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition or sputtering.

Then, a top cover layer 206 is formed on the amorphous silicon layer 204. The material of the top cover layer 206 is, for example, silicon dioxide. The method of formation is, for example, low pressure chemical vapor deposition or plasma enhanced chemical vapor deposition. Alternatively, a silicon dioxide layer is formed on the substrate 200 by sputtering. Thereafter, a first laser annealing process 208 is performed, wherein the first laser annealing process 208 is, for example, irradiating the cap layer 206 with an excimer laser, so that the amorphous silicon layer 204 is almost completely melted, and the excimer The energy density of the laser is, for example, about 50 to 500 mJ/cm ² .

Next, as shown in FIG. 2B , the amorphous silicon layer 204 undergoes a crystallization step to form a polysilicon layer 210 . Furthermore, since the capping layer 206 is formed on the amorphous silicon layer 204 , when the amorphous silicon layer 204 is crystallized to form the polysilicon layer 210 , a plurality of holes 212 will be randomly formed in the polysilicon layer 210 . (Only represented by a hole 212 in Fig. 2B)

In the above process, the reason for forming the hole 212 in the polysilicon layer 210 is mainly because the cohesive force of the polysilicon itself will be greater than the adhesion of the polysilicon to the top cover layer (silicon dioxide), so when the amorphous silicon layer 204 is crystallized into polysilicon When the layer 210 is formed, the polysilicon layer 210 shrinks inward to form a hole 212 . Moreover, the formed holes 212 can have a size smaller than sub-micron (ie, smaller than 1 micron), so they can be used in subsequent crystal growth processes.

Next, as shown in FIG. 2C , the top cover layer 206 is removed, wherein the method for removing the top cover layer 206 is, for example, a wet etching method using hydrofluoric acid, or an anisotropic dry etching is applied to the top cover layer 206. craft. Then, part of the insulating layer 202 in the hole 212 is removed to form an opening 214 in the insulating layer 202 in the hole 212 , wherein the method of removing the part of the insulating layer 202 is, for example, formed by wet etching. The diameter of the opening 214 formed by the above-mentioned process is less than about 0.5 micron, so that the crystallization site can be formed in the subsequent process. Moreover, both the hole 212 and the opening 214 form the opening 216 .

Next, as shown in FIG. 2D, a layer of amorphous silicon layer 218 is formed in the polysilicon layer 210 and the opening 216, wherein the amorphous silicon layer 218 is, for example, formed by low-pressure chemical vapor deposition or plasma-enhanced chemical vapor deposition. Or formed by sputtering. Moreover, the formed amorphous silicon layer 218 has a recess 220 at the position of the opening 216 . Then, a second laser annealing process 222 is performed, wherein the second laser annealing process 222 is, for example, irradiating the amorphous silicon layer 218 with an excimer laser, and the energy density of the excimer laser is, for example, 50 to 500 mJ/cm ² left and right, so that the amorphous silicon layer 218 and the polysilicon layer 210 are almost completely melted, and, due to the profile of the opening 216, there will be part of the unmelted amorphous silicon layer 218 at the bottom of the opening 216, as the crystallization step of the subsequent crystallization position. Finally, as shown in FIG. 2E , the amorphous silicon layer 218 that is not completely melted at the bottom of the opening 216 is used as the crystallization site (crystallization site) to carry out the crystallization growth step, so that the molten amorphous silicon layer 218 and the polysilicon layer 210 are separated from the crystallization site. 220 lateral growth (lateral growth, ie the direction indicated by arrow 226 ) to form the polysilicon layer 224 .

second embodiment

Please refer to FIG. 3A to FIG. 3F , which are schematic cross-sectional process diagrams of a method for manufacturing a polysilicon thin film according to a second embodiment of the present invention.

First please refer to FIG. 3A, the method for manufacturing a polysilicon thin film according to the second embodiment of the present invention is to provide a substrate 300, such as a silicon wafer, a glass substrate or a plastic substrate, on the substrate 300 An insulating layer 302 is formed on the substrate. The material of the insulating layer 302 is, for example, silicon dioxide. The forming method is, for example, low-pressure chemical vapor deposition, plasma-enhanced chemical vapor deposition, or sputtering. A silicon dioxide layer is formed on the insulating layer 300, and then an amorphous silicon layer 304 is formed on the insulating layer 302. formed by sputtering.

Then, a top cover layer 306 is formed on the amorphous silicon layer 304. The material of the top cover layer 306 is, for example, silicon dioxide. The method of formation is, for example, low pressure chemical vapor deposition or plasma enhanced chemical vapor deposition. Alternatively, a silicon dioxide layer is formed on the substrate 300 by sputtering. Thereafter, a first laser annealing process 308 is performed, wherein the first laser annealing process 308 is, for example, irradiating the top cover layer 306 with an excimer laser, so that the amorphous silicon layer 304 is almost completely melted, and the excimer laser The energy density is, for example, about 50 to 500mJ/cm ² ,

Next, as shown in FIG. 3B , the amorphous silicon layer 304 is melted and crystallized to form a polysilicon layer 310 . Furthermore, as in the first embodiment, when the amorphous silicon layer 304 is crystallized to form the polysilicon layer 310 , a plurality of holes 312 will be randomly formed in the polysilicon layer 310 . (Only represented by a hole in Figure 3B)

Next, as shown in FIG. 3C , the top cover layer 306 is removed. The method for removing the top cover layer 306 is, for example, a wet etching method using hydrofluoric acid, or an anisotropic dry etching process is applied to the top cover layer 306. . Then, part of the insulating layer 302 in the hole 312 is removed to form an opening 314 in the insulating layer 302 in the hole 312 , wherein the method of removing the part of the insulating layer 302 is, for example, formed by wet etching. The diameter of the opening 314 formed by the above process is less than about 0.5 μm, so it can be suitable for subsequent processes to form crystallization sites. Moreover, both the hole 312 and the opening 314 form the opening 316 .

Next, as shown in FIG. 3D, a dielectric layer 317 is formed in the polysilicon layer 310 and the opening 316, wherein the dielectric layer 317 is formed by, for example, a low pressure chemical vapor deposition method, a plasma enhanced chemical vapor phase A silicon dioxide layer is formed on the substrate 300 by deposition or sputtering. Moreover, the formed dielectric layer 317 will correspond to the contour of the opening 316 and have a recess 320 at the position of the opening 316 .

Next, as shown in FIG. 3E, a layer of amorphous silicon layer 318 is formed on the dielectric layer 317, wherein the amorphous silicon layer 318 is, for example, formed by low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition or A layer of amorphous silicon is formed on the substrate 300 by sputtering. Then, a second laser annealing process 322 is performed, wherein the second laser annealing process 322 is, for example, irradiating the amorphous silicon layer 318 with an excimer laser, and the energy density of the excimer laser is, for example, 50 to 500 mJ/cm ² so that the amorphous silicon layer 322 is almost completely melted.

Finally, as shown in FIG. 3F , the crystallization growth step is performed on the lower recess 320 as the crystallization position (crystallization position), so that the molten amorphous silicon layer 318 grows laterally along the dielectric layer 317 from the lower recess 320 (also That is, the direction indicated by the arrow 326 ) to form the polysilicon layer 324 .

In the second embodiment above, the polysilicon film is formed under the condition that the step coverage of the dielectric layer is good. However, due to the small size of the holes (openings), poor step coverage may occur during the deposition of the dielectric layer. situation, the present invention can also be applied to this situation, and please refer to the following

Description of Examples.

third embodiment

Please refer to FIG. 4A to FIG. 4F , which are schematic cross-sectional process diagrams of a method for manufacturing a polysilicon thin film according to a third embodiment of the present invention.

First please refer to FIG. 4A, the method for manufacturing a polysilicon thin film according to the third embodiment of the present invention is to provide a substrate 400, such as a silicon wafer, a glass substrate or a plastic substrate, on the substrate 400 An insulating layer 402 is formed. The material of the insulating layer 402 is, for example, silicon dioxide. The forming method is, for example, low-pressure chemical vapor deposition, plasma-enhanced chemical vapor deposition, or sputtering on the substrate 400. A layer of silicon dioxide is formed on the insulating layer 402, and then an amorphous silicon layer 404 is formed on the insulating layer 402. formed by sputtering.

Then, a top cover layer 406 is formed on the amorphous silicon layer 404. The material of the top cover layer 406 is, for example, silicon dioxide. The method of formation is, for example, low pressure chemical vapor deposition or plasma enhanced chemical vapor deposition. Alternatively, a silicon dioxide layer is formed on the substrate 400 by sputtering. Thereafter, a first laser annealing process 408 is performed, wherein the first laser annealing process 408 is, for example, irradiating the top cover layer 406 with an excimer laser, so that the amorphous silicon layer 404 is almost completely melted, and the excimer laser The energy density is, for example, about 50 to 500 mJ/cm ² .

Next, as shown in FIG. 4B , the amorphous silicon layer 404 is melted and crystallized to grow to form a polysilicon layer 410 . Furthermore, as described in the foregoing embodiments, when the amorphous silicon layer 404 is crystallized to form the polysilicon layer 410, a plurality of holes 412 (only one hole is shown in FIG. 4B ) will be randomly formed in the polysilicon layer 410 .

Next, as shown in FIG. 4C , the top cover layer 406 is removed, wherein the method for removing the top cover layer 406 is, for example, a wet etching method using hydrofluoric acid, or an anisotropic dry etching process is applied to the top cover layer 406. . Then, part of the insulating layer 402 in the hole 412 is removed to form an opening 414 in the insulating layer 402 in the hole 412 , wherein the method of removing the part of the insulating layer 402 is, for example, a wet etching method. The diameter of the opening 414 formed by the above process is less than about 0.5 μm, so it can be used in subsequent processes to form crystallization sites. Moreover, both the hole 412 and the opening 414 form an opening 416 .

Next, as shown in FIG. 4D, a dielectric layer 417 is formed in the polysilicon layer 410 and the opening 416, wherein the material of the dielectric layer 417 is, for example, silicon dioxide, and the forming method is, for example, a low pressure chemical vapor deposition method. , plasma-enhanced chemical vapor deposition or sputtering to form a silicon dioxide layer on the substrate 400, and, in this embodiment, due to the poor step coverage of the electrical layer 417, A hole 420 is formed in the dielectric layer 417 at the opening 416 .

Next, as shown in FIG. 4E, a layer of amorphous silicon layer 418 is formed on the dielectric layer 417, wherein the amorphous silicon layer 418 is, for example, formed by low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition or formed by sputtering. Then, a second laser annealing process 422 is performed, wherein the second laser annealing process 422 is, for example, irradiating the amorphous silicon layer 418 with an excimer laser, and the energy density of the excimer laser is, for example, 50 to 500 mJ/cm ² about.

Finally, as shown in FIG. 4F , the amorphous silicon layer 418 is melted and crystallized to grow to form a polysilicon layer 424 . In this embodiment, the dielectric layer 417 has a hole 420. When the second laser annealing process 422 is performed, due to the poor thermal conductivity of the hole 420, heat will be accumulated above the hole 420. Therefore, during the crystallization process, the hole 420 The temperature of the upper amorphous silicon layer 418 is higher than that of the two sides, and can maintain a longer crystallization time. Therefore, the crystallization position in this embodiment is the lowest temperature point on both sides (not shown in the figure), and grows laterally along the dielectric layer 417 from the crystallization position toward the direction of the hole 420 (that is, as shown by the arrow 426 direction), and the polysilicon layer 424 with good crystal grains can also be formed.

Moreover, although not shown in the above-mentioned first to third embodiments, the present invention can also form a layer and the insulating layer 202 between the substrate 200, 300, 400 and the insulating layer 202, 302, 402 , 302 , 402 are insulating layers of different materials, such as silicon nitride, to serve as buffer protection layers for the substrates 200 , 300 , 400 .

As mentioned above, the present invention forms a top cover layer on the amorphous silicon layer, and performs a laser annealing process to crystallize the amorphous silicon layer into a polysilicon layer, that is, it can form a layer smaller than a deep layer in the polysilicon layer or even the insulating layer. Micron pores. Therefore, there is no need to perform complicated processes such as exposure, photolithography, and forming a deposition layer, and the production capacity can be increased.

Moreover, the present invention does not require precise control of process conditions such as the formation of the top cover layer and the first laser annealing process, that is, holes with a size smaller than sub-micron in depth can be formed in the polysilicon layer or even the insulating layer as the crystallization site, so the present invention The invention can have a large process margin.

In addition, in the process of forming the dielectric layer, even if there is a second hole in the dielectric layer due to the poor step coverage of the dielectric layer, the present invention can still carry out the crystallization growth process of the polysilicon film, and can also The present invention has a higher process margin.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the method and technical content disclosed above to make some changes or modifications to equivalent embodiments with equivalent changes, but any content that does not depart from the technical solution of the present invention, Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims (14)

1. A method for manufacturing a polysilicon film, characterized in that it at least comprises the following steps: providing a substrate; sequentially forming an insulating layer, a first amorphous silicon layer and a top cover layer on the substrate; performing a first excimer laser process, so that the first amorphous silicon layer forms a first polysilicon layer having at least one hole; remove the top cover layer; removing part of the insulating layer in the hole by wet etching to form a first opening in the insulating layer, and the hole and the first opening form a second opening; forming a second amorphous silicon layer in the second opening and on the surface of the first polysilicon layer, wherein the second amorphous silicon layer has a depression at the position of the second opening; and Carrying out a second excimer laser process, taking the unmelted second amorphous silicon layer at the bottom of the second opening as the crystallization site, and performing a crystal growth step to make the second amorphous silicon layer and the first polysilicon layer layer forms a second polysilicon layer. 2. The method for manufacturing a polysilicon thin film according to claim 1, wherein the material of the top layer comprises silicon dioxide. 3. The method of manufacturing polysilicon thin film according to claim 1, wherein said method of removing part of the insulating layer in the hole by wet etching comprises wet etching using hydrofluoric acid. 4. The method for manufacturing a polysilicon thin film according to claim 1, wherein the diameter of the second opening is less than 1 micron. 5. A method for manufacturing a polysilicon film, characterized in that it at least includes the following steps: providing a substrate; sequentially forming an insulating layer, a first amorphous silicon layer and a top cover layer on the substrate; performing a first excimer laser process, so that the first amorphous silicon layer forms a first polysilicon layer having at least one hole; remove the top cover layer; removing part of the insulating layer in the hole by wet etching to form a first opening in the insulating layer, and the hole and the first opening form a second opening; forming a dielectric layer in the second opening and on the surface of the first polysilicon layer, wherein the dielectric layer has a depression in the second opening; forming a second amorphous silicon layer on the dielectric layer; and Carrying out a second excimer laser process, taking the recess as the crystallization position, and performing a crystallization growth step so that the second amorphous silicon layer forms a second polysilicon layer. 6. The method for manufacturing a polysilicon thin film according to claim 5, wherein the material of the top layer comprises silicon dioxide. 7. The method for manufacturing polysilicon thin film according to claim 5, wherein said wet etching method for removing part of the insulating layer in the hole comprises wet etching using hydrofluoric acid. 8. The method for manufacturing a polysilicon thin film according to claim 5, wherein the material of the dielectric layer comprises silicon dioxide. 9. The method for manufacturing a polysilicon thin film according to claim 5, wherein the diameter of the second opening is less than 1 micron. 10. A method for manufacturing a polysilicon film, characterized in that it at least includes the following steps: providing a substrate; sequentially forming an insulating layer, a first amorphous silicon layer and a top cover layer on the substrate; performing a first excimer laser process, so that the first amorphous silicon layer forms a first polysilicon layer having at least a first hole; remove the top cover layer; removing part of the insulating layer in the hole by wet etching to form a first opening in the insulating layer, and the first hole and the first opening form a second opening; forming a dielectric layer in the second opening and on the surface of the first polysilicon layer, wherein a second hole is formed in the dielectric layer at the second opening; forming a second amorphous silicon layer on the dielectric layer; and performing a second excimer laser process, wherein the temperature of the second amorphous silicon layer on the second hole is higher than that of other parts of the second amorphous silicon layer, and crystallizes and grows to make the second amorphous silicon layer The silicon layer forms a second polysilicon layer. 11. The method for manufacturing a polysilicon thin film according to claim 10, wherein the material of the top layer comprises silicon dioxide. 12. The method of manufacturing polysilicon thin film according to claim 10, wherein said wet etching method to remove part of the insulating layer in the hole comprises a hydrofluoric acid wet etching method. 13. The method of manufacturing a polysilicon thin film according to claim 10, wherein the material of the dielectric layer comprises silicon dioxide. 14. The method for manufacturing a polysilicon thin film according to claim 10, wherein the diameter of the second opening is less than 1 micron.

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