Low-temperature polysilicon membrane and preparation method thereof, thin-film transistor and display device

• US 9,559,159 B2
• Filed: 04/23/2014
• Issued: 01/31/2017
• Est. Priority Date: 12/24/2013
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: BOE Technology Group Co., Ltd.
• Inventors: Zhang, Huijuan
• Primary Examiner(s): Nguyen, Dao H
• Application Number:
  US14/421,955
• Publication Number:
  US 20160035819A1
• Time in Patent Office: 1,014 Days
• Field of Search: 257/66, 257/71, 257/72, 257/88, 257/E21.134, 257/E21.413, 257/E21.461, 257/E29.278, 257/E29.292, 257/E33.053, 257/E33.062, 438/24, 438/149, 438/166, 438/479, 438/486, 438/487, 438/778
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02502 consisting of two layers
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 27/1281 by using structural features to control crystal growth, e.g. placement of grain filters
• CPC Class Codes: H01L 27/1285 using control of the annealing or irradiation parameters, e.g. using different scanning direction or intensity for different transistors
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/6675 Amorphous silicon or polysilicon transistors
• CPC Class Codes: H01L 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785

Abstract

A method for preparing an LTPS membrane, including: forming an amorphous silicon (a-Si) layer (S3) on a substrate (S1) by a patterning process, in which the a-Si layer (S3) comprises a plurality of convex structures (S32) and etched areas (S31) which are disposed along circumference of the plurality of convex structures and partially etched; and performing excimer laser crystallization (ELC) on the a-Si layer (S3) and obtaining the LTPS membrane. A thin-film transistor (TFT) and a display device are further disclosed, which are used for overcoming poor uniformity of the polysilicon membrane prepared by the ELC technology.

Claims

1. A method for preparing a low temperature poly-silicon (LTPS) membrane, comprising:

forming a pattern of an amorphous silicon (a-Si) layer on a substrate by a patterning process, wherein the a-Si layer comprises a plurality of convex structures and an etched area which is disposed along circumference of the plurality of convex structures and partially etched, and the plurality of convex structures are connected to each other by amorphous silicon in the etched area;

depositing an insulation layer, used for preventing heat loss on a surface of the a-Si layer, on the a-Si layer of the substrate; and

performing excimer laser crystallization (ELC) on the a-Si layer with the insulation layer being on the surface of the a-Si layer and obtaining the LTPS membrane.

2. The method according to claim 1, comprising:

forming a buffer layer on the substrate and forming the a-Si layer on the buffer layer on the substrate.

3. The method according to claim 2, wherein the forming the pattern of the a-Si layer on the substrate by the patterning process comprises:

depositing a layer of a-Si membrane on the substrate; and

selectively etching the a-Si membrane, forming an etched area of the a-Si layer in an etched area of the a-Si membrane, and forming the plurality of convex structures of the a-Si layer in non-etched areas of the a-Si membrane.

4. The method according to claim 1, wherein the forming the pattern of the a-Si layer on the substrate by the patterning process comprises:

depositing a layer of a-Si membrane on the substrate; and

selectively etching the a-Si membrane, forming the etched area of the a-Si layer in an etched area of the a-Si membrane, and forming the plurality of convex structures of the a-Si layer in non-etched areas of the a-Si membrane.

5. The method according to claim 1, wherein the plurality of convex structures are equidistantly distributed on the a-Si layer.

6. The method according to claim 1, wherein the insulation layer comprises a silicon dioxide (SiO₂) or silicon nitride (SiNx) single-layer film or a SiO₂ and SiNx composite layer film.

7. A low temperature poly-silicon (LTPS) membrane, prepared by the method according to claim 1.

8. A thin-film transistor (TFT), adopting the LTPS membrane according to claim 7 as an active layer.

9. A display device, comprising the TFT according to claim 8.

10. A method for manufacturing a thin film transistor (TFT), comprising:

forming a pattern of an a-Si layer on a substrate by a first patterning process, wherein the a-Si layer comprises a plurality of convex structures and an etched area which is disposed along circumference of the plurality of convex structures and partially etched, and the plurality of convex structures are connected to each other by amorphous silicon in the etched area;

depositing an insulation layer, used for preventing heat loss on a surface of the a-Si layer, on the a-Si layer of the substrate;

performing an ELC process on the a-Si layer with the insulation layer being on the surface of the a-Si layer and obtaining an LTPS membrane; and

forming a pattern of an active layer by performing a second patterning process on the LTPS membrane.

11. The method according to claim 10, before the forming the pattern of the a-Si layer, further comprising:

forming a buffer layer on the substrate;

or forming a pattern of a gate electrode on the substrate by a third patterning process and forming a buffer layer on the substrate provided with the gate electrode.

12. The method according to claim 10, wherein the forming the pattern of the a-Si layer on the substrate by the first patterning process comprises:

depositing a layer of a-Si membrane on the substrate; and

selectively etching the a-Si membrane, forming the etched area of the a-Si layer in an etched area of the a-Si membrane, and forming the plurality of convex structures of the a-Si layer in non-etched areas of the a-Si membrane.

13. The method according to claim 10, wherein the plurality of convex structures are equidistantly distributed on the a-Si layer.

14. The method according to claim 10, after the performing the ELC process on the a-Si layer, further comprising:

removing the insulation layer on the LTPS membrane.