CN112151354A - Surface treatment method for polycrystalline silicon film - Google Patents
Surface treatment method for polycrystalline silicon film Download PDFInfo
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- CN112151354A CN112151354A CN201910562548.8A CN201910562548A CN112151354A CN 112151354 A CN112151354 A CN 112151354A CN 201910562548 A CN201910562548 A CN 201910562548A CN 112151354 A CN112151354 A CN 112151354A
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- amorphous silicon
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02518—Deposited layers
- H01L21/02521—Materials
- H01L21/02524—Group 14 semiconducting materials
- H01L21/02532—Silicon, silicon germanium, germanium
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02518—Deposited layers
- H01L21/02587—Structure
- H01L21/0259—Microstructure
- H01L21/02595—Microstructure polycrystalline
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02656—Special treatments
- H01L21/02658—Pretreatments
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02656—Special treatments
- H01L21/02664—Aftertreatments
- H01L21/02667—Crystallisation or recrystallisation of non-monocrystalline semiconductor materials, e.g. regrowth
- H01L21/02675—Crystallisation or recrystallisation of non-monocrystalline semiconductor materials, e.g. regrowth using laser beams
Abstract
A method for treating the surface of polysilicon film includes such steps as providing a substrate consisting of glass, silicon nitride layer, silicon oxide layer and amorphous silicon layer with primary oxide layer; performing a first cleaning step on the substrate to remove impurities on a surface of the substrate; performing a first wet etching step on the substrate from which the impurities have been removed to remove a native oxide layer on the amorphous silicon layer; performing a second cleaning step on the substrate from which the native oxide layer on the amorphous silicon layer has been removed, so as to form an oxide layer on the amorphous silicon layer; performing a second wet etching step on the amorphous silicon layer with the oxide layer to remove a part of the oxide layer on the amorphous silicon layer; washing and drying the substrate; and performing a laser irradiation step on the amorphous silicon layer so that the amorphous silicon layer forms a polycrystalline silicon layer with a rough surface.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a polycrystalline silicon film surface treatment method.
Background
In the prior art, the polysilicon thin film is manufactured by cleaning the polysilicon thin film on a substrate before laser irradiation and growing an oxide layer. Wherein the substrate comprises glass, a silicon nitride (SiNx) layer and a silicon oxide (SiOx) layer from bottom to top in sequence, an amorphous silicon layer is arranged on the silicon oxide layer, and the step of cleaning the substrate at least comprises the following steps: first, metal ions and organic substances on the surface of the substrate are removed by Ozone water (Ozone water) having a concentration of 20ppm to 25 ppm. And then removing the native oxide layer by using hydrofluoric acid (HF) with the concentration of 0.5-1%, wherein the removed thickness is 2nm-4 nm. Then, an oxide layer is formed on the surface of the amorphous silicon by using ozone water having a concentration of 20ppm to 25 ppm. The substrate is then washed with water and dried. Finally, an Excimer Laser Annealing (ELA) process is performed to complete the fabrication of the polysilicon. The average roughness of the surface of the polysilicon prepared by the method is 10 nm-13 nm, the thickness of the silicon nitride layer is 50 nm-100 nm, the thickness of the silicon oxide layer is 200 nm-300 nm, and the thickness of the amorphous silicon layer is 40 nm-60 nm.
However, in the process of fabricating the polysilicon thin film according to the above-mentioned process method, excimer laser is used to irradiate the surface of the amorphous silicon, but a Native oxide layer (Native oxide) is formed on the surface of the amorphous silicon, and the Native oxide layer causes the roughness of the polysilicon surface after laser crystallization to be increased, so that when the polysilicon thin film is used as a TFT display, the coverage (coverage) of the gate insulating layer deposited on the polysilicon thin film is deteriorated, resulting in the occurrence of leakage current.
Disclosure of Invention
In view of the drawbacks of the prior art, the primary objective of the present invention is to disclose a method for treating the surface of a polysilicon thin film, which comprises a step of cleaning the amorphous silicon thin film with ozone water and a step of wet etching, wherein the roughness of the polysilicon thin film formed by the method is reduced by 10% -46% compared with the roughness of the polysilicon thin film formed by the prior art when the amorphous silicon thin film is irradiated by excimer laser annealing.
According to the above object, the present invention discloses a method for treating the surface of a polysilicon thin film, comprising the steps of providing a substrate comprising, in order from bottom to top, glass, a silicon nitride layer, a silicon oxide layer and an amorphous silicon layer, wherein the amorphous silicon layer has a native oxide layer thereon; performing a first cleaning step on the substrate to remove impurities on a surface of the substrate; performing a first wet etching step on the substrate from which the impurities have been removed to remove a native oxide layer on the amorphous silicon layer; performing a second cleaning step on the substrate from which the native oxide layer on the amorphous silicon layer has been removed, so as to form an oxide layer on the amorphous silicon layer; performing a second wet etching step on the amorphous silicon layer with the oxide layer to remove a part of the oxide layer on the amorphous silicon layer; washing and drying the substrate; and performing a laser irradiation step on the amorphous silicon layer so that the amorphous silicon layer forms a polycrystalline silicon layer with a rough surface.
In a preferred embodiment of the present invention, the first cleaning step and the second cleaning step are performed by using ozone water.
In a more preferred embodiment of the invention, the concentration of the ozonated water is 20ppm to 25 ppm.
In a preferred embodiment of the present invention, the impurities are metal ions and/or organic substances.
In a preferred embodiment of the present invention, the first wet etching step and the second wet etching step are respectively performed by using hydrofluoric acid, and the concentration of the hydrofluoric acid is 0.1% -0.25%.
In a preferred embodiment of the present invention, the first wet etching step removes a native oxide layer on the amorphous silicon layer to a thickness of 2nm to 4 nm.
In a more preferred embodiment of the present invention, the first wet etching step is performed for 40 seconds to 60 seconds.
In a more preferred embodiment of the present invention, the second wet etching step is performed for 5 seconds to 10 seconds.
In a preferred embodiment of the present invention, the laser irradiation of the amorphous silicon layer is performed by excimer laser annealing (excimer laser annealing).
In a more preferred embodiment of the present invention, the roughness of the rough surface of the polysilicon layer is 6nm to 9 nm.
Drawings
FIG. 1 is a flow chart illustrating a method for treating a surface of a polysilicon film in accordance with the disclosed technique.
FIGS. 2A-2E are schematic cross-sectional views illustrating steps of a polysilicon thin film surface treatment method in accordance with the disclosed technique.
Detailed Description
So that the manner in which the above recited features and advantages of the present invention can be understood and attained by a person skilled in the art, a more particular description of the invention, briefly summarized above, may be had by reference to the appended drawings, in which like reference numerals refer to like elements, features, and embodiments. The drawings referred to below are schematic representations relating to the features of the invention and are not necessarily drawn to scale. The description of the embodiments related to the present invention will not be repeated, except for those skilled in the art.
Please refer to fig. 1 first. FIG. 1 is a flow chart illustrating a method for treating a surface of a polysilicon film in accordance with the disclosed technique. The steps of fig. 1 are also illustrated in conjunction with the steps of fig. 2A-2E. In fig. 1, step 10: a substrate is provided. In this step, the substrate is sequentially stacked from bottom to top into a glass layer 30, a silicon nitride layer 32, a silicon oxide layer 34 and an amorphous silicon layer 36, and the amorphous silicon layer 36 has a native oxide layer 38 thereon. There may be some impurities left in the substrate, such as metal ions and/or organic matters, so that in order to remove these impurities, step 12 is performed: a first cleaning step is performed on the substrate to remove impurities on the surface of the substrate. In this step, the substrate cleaning solution is made of ozone water 500 having a concentration of 20ppm to 25 ppm.
Then step 14: a first wet etching step is performed on the substrate from which the impurities have been removed to remove a native oxide layer on the amorphous silicon layer. In this step, hydrofluoric acid 520 with a concentration of 0.1% -0.25% is used as an etching solution, and the substrate is etched for 40 seconds-60 seconds, so that the native oxide layer 38 on the amorphous silicon layer 36 can be removed under the above etching conditions, and the thickness of the native oxide layer 38 is 2nm-4nm, as shown in fig. 2C.
In step 16: and performing a second cleaning step on the substrate from which the native oxide layer on the amorphous silicon layer has been removed, so as to form an oxide layer on the amorphous silicon layer. In this step, the cleaning solution of the second cleaning step is performed using ozone water 502 having a concentration of 20ppm to 25ppm, and an oxide layer 40 is formed on the amorphous silicon layer 36 during the cleaning.
Then, in step 18: a second wet etch step is performed on the amorphous silicon layer with the oxide layer to remove a portion of the oxide layer 402 on the amorphous silicon layer 36. In this step, hydrofluoric acid 522 with a concentration of 0.1% -0.25% is also used as an etching solution for 5 seconds-10 seconds to remove the oxide layer 402 formed in step 16.
Following step 20: the substrate was washed with water and dried. And step 22: and performing a laser irradiation step on the amorphous silicon layer so that the amorphous silicon layer forms a polycrystalline silicon layer with a rough surface. In this step, the amorphous silicon layer 36 is irradiated by Excimer Laser Annealing (ELA) 540. According to the above steps 10-20, the surface roughness of the polysilicon thin film 362 can be reduced to 10% -46% of the prior art, and if the roughness in the prior art is 10 nm-13 nm, the roughness can be reduced to 6nm-9 nm. Which is advantageous for the application of the polysilicon film 362 in the subsequent process.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; while the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (10)
1. The surface treatment method of the polycrystalline silicon film is characterized by comprising the following steps:
providing a substrate, wherein the substrate sequentially comprises glass, a silicon nitride layer, a silicon oxide layer and an amorphous silicon layer from bottom to top, and a native oxide layer is arranged on the amorphous silicon layer;
performing a first cleaning step on the substrate to remove impurities on a surface of the substrate;
performing a first wet etching step on the substrate from which the impurities have been removed to remove the native oxide layer on the amorphous silicon layer;
performing a second cleaning step on the substrate from which the native oxide layer on the amorphous silicon layer has been removed, so that an oxide layer is formed on the amorphous silicon layer;
performing a second wet etching step on the amorphous silicon layer with the oxide layer to remove a portion of the oxide layer on the amorphous silicon layer;
washing and drying the substrate; and
and performing a laser irradiation step on the amorphous silicon layer, so that the amorphous silicon layer forms a polycrystalline silicon layer with a rough surface.
2. The method for surface treatment of polysilicon thin film according to claim 1, wherein the first cleaning step and the second cleaning step are performed using ozone water.
3. The method for surface treatment of polycrystalline silicon thin film according to claim 2, wherein the concentration of the ozone water is 20ppm to 25 ppm.
4. The method for surface treatment of a polysilicon thin film according to claim 1, wherein the impurities are metal ions and/or organic substances.
5. The method for treating the surface of a polysilicon thin film according to claim 1, wherein the first wet etching step and the second wet etching step are respectively performed by using hydrofluoric acid, and the concentration of the hydrofluoric acid is 0.1% -0.25%.
6. The method for surface treatment of polysilicon thin film according to claim 1, wherein the first wet etching step is performed to remove the native oxide layer on the amorphous silicon layer to a thickness of 2nm to 4 nm.
7. The method for surface treatment of a polycrystalline silicon thin film according to claim 1, 5 or 6, wherein the first wet etching step is performed for 40 seconds to 60 seconds.
8. The method for surface treatment of a polycrystalline silicon thin film according to claim 1 or 5, wherein the second wet etching step is performed for 5 seconds to 10 seconds.
9. The method of claim 1, wherein the laser irradiation of the amorphous silicon layer is performed by excimer laser annealing (excimer laser annealing).
10. The surface treatment method of a polycrystalline silicon thin film according to claim 1, wherein the roughness of the roughness surface of the polycrystalline silicon layer is 6nm to 9 nm.
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| CN201910562548.8A CN112151354A (en) | 2019-06-26 | 2019-06-26 | Surface treatment method for polycrystalline silicon film |
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| CN201910562548.8A CN112151354A (en) | 2019-06-26 | 2019-06-26 | Surface treatment method for polycrystalline silicon film |
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| CN104465371A (en) * | 2014-12-31 | 2015-03-25 | 深圳市华星光电技术有限公司 | Excimer laser annealing pretreatment method, thin film transistor and production method of thin film transistor |
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| CN105261592A (en) * | 2015-10-30 | 2016-01-20 | 深圳市华星光电技术有限公司 | Method for preparing low temperature polycrystalline silicon with low surface roughness, and low temperature polycrystalline silicon |
| CN107393832A (en) * | 2017-08-11 | 2017-11-24 | 武汉华星光电半导体显示技术有限公司 | A kind of method for improving polysilicon surface flatness |
| CN109742015A (en) * | 2019-01-08 | 2019-05-10 | 京东方科技集团股份有限公司 | Film surface processing method and film surface processing equipment |
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2019
- 2019-06-26 CN CN201910562548.8A patent/CN112151354A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US20030089911A1 (en) * | 2001-08-27 | 2003-05-15 | Kenji Kasahara | Semiconductor device and method of manufacturing the same |
| KR20070067262A (en) * | 2005-12-23 | 2007-06-28 | 삼성에스디아이 주식회사 | Crystallization method and method of fabricating tft using the same |
| CN103367446A (en) * | 2012-03-26 | 2013-10-23 | 英飞凌科技奥地利有限公司 | Stress-reduced field-effect semiconductor device and method for forming therefor |
| CN103745925A (en) * | 2013-11-14 | 2014-04-23 | 上海和辉光电有限公司 | Planarization polysilicon film manufacturing method |
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Application publication date: 20201229 |