CN108761997A - The preparation method of light shield and thin film transistor (TFT) - Google Patents

Abstract

The present invention provides a photomask, comprising a first light-shielding film and a second light-shielding film parallel to and opposite to the first light-shielding film, the first light-shielding film includes a first light-shielding film facing the second light-shielding film section, the first section includes a first side facing the second light-shielding film, the first side is a zigzag structure protruding toward the second light-shielding film, and the second light-shielding film includes a The first section is spaced opposite to the second section, the second section includes a second side facing the first section, and the second side is a zigzag structure opposite to the first side. The present invention also provides a method for preparing a thin film transistor. Exposure is performed by using the photomask, and light interferes when passing through the zigzag structure of the photomask, so that the pattern finally exposed through the photomask is linear, ensuring The uniform and equal width of the channel between the source and the drain of the prepared small-size thin film transistor is improved, and the electrical performance of the thin film transistor is improved.

Description

Fabrication method of photomask and thin film transistor

technical field

The invention relates to the field of display technology, in particular to a method for preparing a photomask and a thin film transistor.

Background technique

At present, Thin Film Transistor-Liquid Crystal Display (TFT-LCD, Thin Film Transistor-Liquid Crystal Display) has been widely used in televisions, computer screens, notebook computers, mobile phones and other electronic display products. In the field of TFT-LCD display, with the continuous improvement of screen resolution, the pixel size is continuously reduced, which puts forward higher requirements for design and manufacturing process. Thin-film crystal diodes are the smaller structures in pixels, and despite their small size, they play a vital role in charging the pixels. Therefore, there are high requirements for the size control of thin film crystal diodes.

In the thin film transistor of the pixel, there is generally a 3T (the third TFT) with the smallest size, and the design of the photomask forming the source and drain of the 3T is generally shown in Figure 1. However, due to the fillet effect during exposure, the source and drain electrodes of this small-sized TFT will be deformed during final shaping, as shown in Figure 2. At this time, the channel part between the source and the drain is deformed, so that the difference between different parts such as L-mid and L-tail will become larger, which will lead to the difference between the channel and the channel during the actual operation of the 3T device. The design values vary greatly, so new design methods are needed to ensure the stability of the channel width.

Contents of the invention

The object of the present invention is to provide a photomask, which can ensure the uniform width of the channel when forming the source and drain of the thin film transistor.

The invention also provides a preparation method of the thin film transistor.

The mask of the present invention includes a first light-shielding film and a second light-shielding film parallel to and opposite to the first light-shielding film, the first light-shielding film includes a first section facing the second light-shielding film, The first section includes a first side facing the second light-shielding film, the first side is a zigzag structure protruding toward the second light-shielding film, and the second light-shielding film includes a The first section is spaced opposite to the second section, the second section includes a second side facing the first section, and the second side is a zigzag structure opposite to the first side.

Wherein, the first section includes a first end surface connected to the first side, the plane where the first end surface is located intersects with the vertices of the sawtooth in the sawtooth structure of the first side, and the second section It includes a second end surface connected to the second side, and the plane where the second end surface is located intersects with the vertices of the sawtooth in the sawtooth structure of the second side.

Wherein, the photomask includes a semi-permeable film, and the first light-shielding film and the second light-shielding film are arranged on the surface of the semi-permeable film.

Wherein, the height of the sawtooth in the sawtooth structure of the first side and the second side is between 0.5 μm and 2.0 μm.

Wherein, the semi-permeable film includes a first side and a second side that are parallel and opposite to each other, the first light-shielding film includes a third section that is opposite to the first section, and the third section extends out of the The first side of the semi-permeable membrane, the second light-shielding film includes a fourth segment opposite to the second segment, and the fourth segment extends out of the second side of the semi-permeable membrane.

Wherein, the first end surface of the first segment in the first light-shielding film is spaced apart from the second side of the semi-permeable film, and the second end surface of the second segment in the second light-shielding film is spaced from the second side of the semi-permeable film. The first sides of the semi-permeable membrane are arranged at intervals.

Wherein, the first section includes a third side opposite to the first side, the third side is a zigzag structure protruding away from the first side, and the second section includes a The second side is opposite to the fourth side, and the fourth side is a zigzag structure protruding away from the second side.

Wherein, the plane where the first end surface of the first section is located intersects with the apex of the sawtooth in the sawtooth structure of the third side, and the second end surface of the second section intersects with the sawtooth apex of the fourth side. The vertices of the sawtooth in the structure intersect.

Wherein, the light transmittance of the first light-shielding film and the second light-shielding film is 0%.

The preparation method of the thin film transistor of the present invention comprises:

providing a substrate;

forming a first metal layer on the substrate;

A photomask is used to pattern the first metal layer to form a source and a drain, wherein the photomask is the above-mentioned photomask.

The photomask of the present invention is provided with a zigzag structure at the relative position of the first light-shielding film and the second light-shielding film. During the exposure process, light interferes when passing through the zigzag structure, so that the pattern finally exposed through the photomask It is linear and utilizes the optical compensation effect of the zigzag structure to ensure uniform and equal width of the channel between the source and drain of the prepared small-sized thin film transistor and improve the electrical performance of the thin film transistor.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 is a schematic structural diagram of a photomask in the prior art.

FIG. 2 is a source and drain pattern prepared by using the mask described in FIG. 1 .

FIG. 3 is a schematic structural view of the first embodiment of the photomask of the present invention.

FIG. 4 is a schematic structural view of the second embodiment of the photomask of the present invention.

Fig. 5 is a flow chart of the manufacturing method of the thin film transistor of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Referring to FIG. 3 , a preferred embodiment of the present invention provides a photomask 100 , which is used to form specific patterns in the manufacturing process of thin film transistors, and is especially suitable for manufacturing thin film transistors with small sizes. The photomask 100 includes a first light shielding film 10 and a second light shielding film 20 parallel to and opposite to the first light shielding film 10, and the first light shielding film 10 includes a film facing the second light shielding film 20. The first segment 11, the first segment 11 includes a first side 111 facing the second light-shielding film 20, the first side 111 is a zigzag structure protruding toward the second light-shielding film 20, so The second light-shielding film 20 includes a second section 21 opposite to the interval of the first section 11, the second section 21 includes a second side 211 facing the first section 11, and the second side 211 is a zigzag structure opposite to the first side 111 .

When using the photomask of the present invention to pattern the metal layer to form the source and drain in the thin film transistor manufacturing process, due to the zigzag structure on the first light-shielding film and the second light-shielding film in the photomask The existence of the light will interfere when passing through the sawtooth structure, so that the final pattern inside the channel between the source and the drain is the original design of the straight line, and the sawtooth compensation principle makes the source and drain The edge uniformity of the channel pattern between is better.

The first section 11 includes a first end surface 112 connected to the first side 111, the plane where the first end surface 112 is located intersects with the vertex of the sawtooth in the sawtooth structure of the first side 111, the The second segment 21 includes a second end surface 212 connected to the second side 211 , and the plane of the second end surface 212 intersects the vertex of the sawtooth in the sawtooth structure of the second side 211 . In this embodiment, the sawtooth in the sawtooth structure of the first side 111 and the second side 211 is acute-angled, and the bottommost acute-angled sawtooth vertex in the sawtooth structure of the first side 111 is located at On the first end surface 112 of the first section 11 , the apex of the uppermost acute-angled sawtooth in the sawtooth structure of the second side 211 is located on the second end surface 212 of the second section 21 . It can be understood that, in other implementations of this embodiment, the sawtooth in the sawtooth structure of the first side 111 and the second side 211 can also be right angled or obtuse, as long as light can pass through Interference will occur when the sawtooth pattern is formed so that the final pattern is a straight line. Further, the height of the sawtooth in the sawtooth structure of the first side 111 and the second side 211 is between 0.5 μm and 2.0 μm, preferably, the height of the sawtooth is about 1.0 μm to 1.5 μm . Further, the first light-shielding film 10 and the second light-shielding film 20 are made of metal material chromium, and their light transmittance is 0%.

The mask 100 includes a semi-permeable film 30 , and the first light-shielding film 10 and the second light-shielding film 20 are disposed on a surface of the semi-permeable film 30 . Specifically, the semipermeable film 30 includes a first side 31 and a second side 32 that are parallel and opposite to each other, and the first light shielding film 10 includes a third end 12 that is opposite to the first section 11. The third end 12 extends out of the first side 31 of the semi-permeable film 30, the second light-shielding film 20 includes a fourth end 22 opposite to the second section 21, and the fourth end 22 extends out of the The second side 32 of the semi-permeable membrane 30 is formed so as to form the source electrode and the drain electrode with complete shapes during the patterning process. Further, the first end surface 112 of the first section 11 in the first light-shielding film 10 is spaced apart from the second side 32 of the semi-permeable film 30 , and the second section in the second light-shielding film 20 The second end surface 212 of 21 is spaced apart from the first side 31 of the semi-permeable membrane 30 to reduce the amount of etching during the formation of the source and drain. Generally speaking, the semi-permeable film 30 is made of metal chromium oxide, and its light transmittance is less than 1, so as to improve pixel end difference and improve resolution. In this embodiment, the light transmittance of the semi-permeable film 30 is preferably 40%, and the light transmittance of the semi-permeable film 30 in the mask 100 of the present invention is not limited to 40%.

Further, the semi-permeable membrane 30 also includes a third side 33 and a fourth side 34 connecting the first side 31 and the second side 32, the third side 33 and the fourth side 34 are parallel And relative settings. Referring again to FIG. 1 , in the first embodiment of the photomask 100 of the present invention, the first section 11 of the first light shielding film 10 includes a third side 113 opposite to the first side 111 , the third side 113 is a straight line, the third side 113 is aligned with the third side 33 of the semi-permeable film 30, the second section 21 of the second light shielding film 20 includes the second The side 211 is opposite to the fourth side 213 , the fourth side 213 is a straight line, and the fourth side 213 is aligned with the fourth side 34 of the semipermeable membrane 30 .

Please refer to FIG. 4 , in the second embodiment of the photomask 100 of the present invention, the difference from the above-mentioned first embodiment is that the third side 113 protrudes away from the first side 111 The plane where the first end face 112 is located intersects with the vertex of the sawtooth in the sawtooth structure of the third side 113, and the fourth side 213 is a sawtooth protruding away from the second side 211 structure, the plane where the second end surface 212 is located intersects with the vertices of the sawtooth in the sawtooth structure of the fourth side 213, so that the pattern forming the outside of the channel between the source and the drain is the originally designed straight line , the channel pattern between the source and the drain is further improved, and the electrical performance of the prepared thin film transistor is improved. Likewise, the height of the sawtooth in the sawtooth structure of the third side 113 and the fourth side 114 is between 0.5 μm˜2.0 μm, preferably, the size of the sawtooth is about 1.0 μm˜1.5 μm.

The photomask of the present invention is provided with a zigzag structure on the relative position of the first light-shielding film and the second light-shielding film. When the source and drain of the thin film transistor are formed by exposure using the photomask, the light will interfere with the sawtooth of the zigzag structure. After passing through the semi-permeable film to form a linear pattern, and the end of the sawtooth structure corresponds to the apex of the sawtooth to compensate for the rounded corner effect during the exposure process, making the final pattern closer to a right angle, ensuring the formation of thin film transistors with smaller sizes The uniform width of the channel between the source and the drain improves the electrical performance of the thin film transistor.

Please refer to FIG. 5 , the present invention also provides a method for manufacturing a thin film transistor, which is used for manufacturing a thin film transistor with a smaller size, such as the third thin film transistor with the smallest size among pixel thin film transistors. The preparation method of the thin film transistor comprises:

S1, providing a substrate. The substrate includes a base substrate, a gate disposed on the base substrate, and a gate insulating layer covering the gate.

S2, forming a first metal layer on the substrate. Specifically, the first metal layer is formed on the substrate by using physical vapor deposition, chemical vapor deposition or electron evaporation technology, and the material of the first metal layer includes but is not limited to Al, Ag, Cu, Mo or Ti, etc. one or more conductive materials.

S3, patterning the first metal layer by using a photomask to form a source electrode and a drain electrode. Wherein, the photomask is the above-mentioned photomask 100 . Specifically, the patterning process includes coating photoresist, exposure, etching, and photoresist removal. In the exposure step, the above-mentioned photomask 100 is used for exposure, so that the formed channel between the source electrode and the drain electrode The uniform width is beneficial to improve the electrical performance of the thin film transistor.

It should be noted that the preparation method of the thin film transistor described in this application also includes forming an insulating layer, a buffer layer, a passivation layer and other functional layers on the source and the drain to form a complete thin film transistor structure, This application does not describe in detail here.

What is disclosed above is only a preferred embodiment of the present invention, and certainly cannot limit the scope of rights of the present invention with this. Those of ordinary skill in the art can understand the whole or part of the process of realizing the above-mentioned embodiment, and make according to the claims of the present invention The equivalent changes still belong to the scope covered by the invention.

Claims (10)

1. A light shield, characterized in that, the light shield comprises a first light shielding film and a second light shielding film parallel and opposite to the first light shielding film, the first light shielding film comprises a second light shielding film parallel to the second light shielding film The first section facing the light-shielding film, the first section includes a first side facing the second light-shielding film, and the first side is a zigzag structure protruding toward the second light-shielding film, so The second shading film includes a second section spaced opposite to the first section, the second section includes a second side facing the first section, and the second side is opposite to the first side Saw-toothed structure with opposing sides. 2. The photomask according to claim 1, wherein the first section includes a first end face connected to the first side, and the plane where the first end face is located is the same as the plane of the first side The apex of the sawtooth in the sawtooth structure intersects, the second section includes a second end face connected to the second side, and the plane where the second end face is located is the same as the apex of the sawtooth in the sawtooth structure of the second side intersect. 3. The photomask according to claim 2, wherein the photomask comprises a semi-permeable film, and the first light-shielding film and the second light-shielding film are disposed on a surface of the semi-permeable film. 4 . The photomask according to claim 1 , wherein the height of the sawtooth in the sawtooth structure of the first side and the second side is between 0.5 μm and 2.0 μm. 5. The photomask according to claim 3, wherein the semi-permeable film includes a first side and a second side that are parallel and oppositely arranged, and the first light-shielding film includes a side that is arranged oppositely to the first section. The third section, the third section extends out of the first side of the semi-permeable film, the second light-shielding film includes a fourth section opposite to the second section, the fourth section extends out of the the second side of the semipermeable membrane. 6. The photomask according to claim 5, wherein the first end surface of the first section in the first light-shielding film is spaced from the second side of the semi-permeable film, and the second light-shielding film The second end surface of the second section of the membrane is spaced apart from the first side of the semi-permeable membrane. 7. The photomask of claim 2, wherein the first section includes a third side disposed opposite to the first side, the third side facing away from the first side The second section includes a fourth side opposite to the second side, and the fourth side is a zigzag structure protruding away from the second side. 8. The photomask according to claim 7, wherein the plane where the first end face of the first section is located intersects with the apex of the sawtooth in the sawtooth structure of the third side, and the second section The second end surface of the fourth side intersects with the vertices of the sawtooth in the sawtooth structure of the fourth side. 9 . The photomask according to claim 1 , wherein the light transmittance of the first light-shielding film and the second light-shielding film is 0%. 10. A method for preparing a thin film transistor, comprising: providing a substrate; forming a first metal layer on the substrate; Patterning the first metal layer by using a photomask to form the source and the drain, wherein the photomask is the photomask described in any one of claims 1-9.