Semiconductor substrate and its preparation method

Abstract

The present invention provides a semiconductor substrate and a method for preparing the same. The method includes: heat-treating a nitrogen-doped silicon substrate to diffuse nitrogen from the silicon substrate to the surface of the silicon substrate, thereby forming nucleation sites of a predetermined size on the surface of the silicon substrate by the nitrogen; and growing a polycrystalline silicon thin film on the nucleation sites to form a semiconductor substrate.

Claims

1. A method for preparing a semiconductor substrate, the method comprising: A nitrogen-doped silicon substrate is heat-treated to diffuse nitrogen from the substrate to the surface of the substrate, thereby forming nucleation sites of a predetermined size on the surface of the substrate. A polycrystalline silicon thin film is then grown on the nucleation sites to form a semiconductor substrate.

2. The method for preparing a semiconductor substrate as described in claim 1, wherein, The growth of a polycrystalline silicon thin film at the nucleation site includes: forming a seed layer at the nucleation site; and growing a polycrystalline silicon layer on the seed layer.

3. A method for preparing a semiconductor substrate as described in claim 1 or 2, wherein, The nitrogen doping concentration in the silicon substrate is greater than 1E18atom / cm3.

4. A method for preparing a semiconductor substrate as described in claim 1 or 2, wherein, The heat treatment is a rapid heat treatment at 600°C to 1000°C.

5. A method for preparing a semiconductor substrate as described in claim 1 or 2, wherein, The size of the nucleation sites is in the range of 20 to 40 nm, and the grain size of the polycrystalline silicon film is in the range of 80 to 120 nm.

6. The method for preparing a semiconductor substrate as described in claim 5, wherein, In the polycrystalline silicon thin film, the difference between the maximum and minimum grain size is less than 50% of its average grain size.

7. The method for preparing a semiconductor substrate as described in claim 2, wherein, The step of forming the seed layer includes: performing a heat treatment at a temperature of 900°C for 10 minutes to form the seed layer with a grain size in the range of 20~40 nm.

8. The method for preparing a semiconductor substrate as described in claim 7, wherein, The step of growing a polycrystalline silicon layer on the seed layer includes: performing a heat treatment at a temperature of 950°C for 30 minutes to form the polycrystalline silicon layer with a grain size in the range of 80~120 nm.

9. A method for preparing a semiconductor substrate as described in claim 1 or 2, wherein, The steps for growing polycrystalline silicon thin films include: growing polycrystalline silicon thin films using atmospheric pressure chemical vapor deposition, low pressure chemical vapor deposition, or plasma-enhanced chemical vapor deposition.

10. A method for preparing a semiconductor substrate as described in claim 9, wherein, The step of growing the polycrystalline silicon thin film is carried out at a temperature of 400~1000℃ for a duration of 10~60 minutes.

11. A method for preparing a semiconductor substrate as described in claim 1 or 2, wherein, The semiconductor substrate has a resistance greater than 1000 ohm-cm, and the polycrystalline silicon thin film has a resistivity greater than 1000 ohm-cm.

12. A method for preparing a semiconductor substrate as described in claim 1 or 2, wherein, The preparation method further includes: pulling a nitrogen-doped single-crystal silicon rod; and cutting a nitrogen-doped silicon substrate from the single-crystal silicon rod.

13. A semiconductor substrate, the semiconductor substrate comprising: Nitrogen-doped silicon substrate; And a polycrystalline silicon thin film disposed on the silicon substrate; wherein the average grain size of the polycrystalline silicon thin film is in the range of 80~120 nm, and the difference between the maximum grain size and the minimum grain size in the polycrystalline silicon thin film is less than 50% of its average grain size.

14. The semiconductor substrate as described in claim 13, wherein, The polycrystalline silicon thin film includes: a seed layer formed on the silicon substrate; and a polycrystalline silicon layer formed on the seed layer.

15. The semiconductor substrate as described in claim 13 or 14, wherein, The nitrogen doping concentration in the silicon substrate is greater than 1E18atom / cm3.

16. The semiconductor substrate as described in claim 14, wherein, The average grain size of the seed layer is in the range of 20~40 nm.

17. The semiconductor substrate as described in claim 13 or 14, wherein, The resistivity of the silicon substrate is greater than 1000 ohm-cm, and the resistivity of the polycrystalline silicon thin film is greater than 1000 ohm-cm.

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