Methods for forming a P-type polysilicon layer in a semiconductor device

1. A method for forming a P-type polysilicon layer in a semiconductor device, comprising:

forming a first silicon atom layer on a semiconductor substrate by atomic layer deposition;

forming a first group IIIA element atom layer on the first silicon atom layer by atomic layer deposition:

forming a gate stack by repeatedly depositing second silicon atom layers and second IIIA element atom layers on the semiconductor substrate by atomic layer deposition several times, wherein the silicon atom layers and the group IIIA element atom layers in the gate stack are alternately deposited; and

forming a P-type polysilicon layer by thermally diffusing the plurality of group IIIA element atom layers in the gate stack into the plurality of silicon atom layers.

2. A method as defined in claim 1 , wherein the first and second silicon atom layers are respectively deposited to a thickness of about 5-100Å.

3. A method as defined in claim 1 , wherein the first and second group IIA element atom layers are respectively deposited to a thickness of about 5-50Å.

4. A method as defined in claim 1 , wherein the first and second group IIIA element atom layers comprise at least one of Al, Ga, In, or Tl.

5. A method as defined in claim 1 , wherein the first and second silicon atom layers are respectively deposited to a thickness of about 5-100Å and the first and second group IIIA clement atom layers arc respectively deposited to a thickness of about 5-50Å, and the first and second group IIIA element atom layers comprise at least one of Al, Ga, In, or Tl.

6. A method as defined in claim 1 , further comprising forming a gate insulating layer on the substrate before forming the gate stack.

7. A method for forming a P-type polysilicon layer in a semiconductor device, comprising:

depositing a silicon atom layer on a semiconductor substrate by atomic layer deposition;

depositing a group IIIA element atom layer on the silicon atom layer by atomic layer deposition:

repeating the silicon atom layer and group IIIA element atom layer depositing steps to form a gate stack: and

forming a P-type polysilicon layer by thermally diffusing the group IIIA element atom layers in the gate stack into the silicon atom layers.

8. A method as defined in claim 7 , wherein the silicon atom layers are respectively deposited to a thickness of about 5-100Å.

9. A method as defined in claim 7 , wherein the group IIIA element atom layers are respectively deposited to a thickness of about 5-50Å.

10. A method as defined in claim 7 , wherein the group IIIA element atom layers comprise at least one of Al, Ga, In, or TI.

11. A method as defined in claim 7 , wherein the method comprises depositing three silicon atom layers and three group IIIA element atom layers.

12. A method as defined in claim 7 , wherein the semiconductor substrate comprises silicon.

13. A method as defined in claim 10 , further comprising forming a gate insulating layer on the substrate before depositing the silicon atom layer and the group IIIA element atom layer.

14. A method as defined in claim 13 , wherein the gate insulating layer comprises an oxide layer.

15. A method as defined in claim 13 , further comprising forming a liner layer on sidewalls of the P-type polysilicon layer and the gate insulating layer.

16. A method as defined in claim 15 , further comprising forming a spacer layer on the liner layer.

17. A method as defined in claim 15 , further comprising forming first and second impurity regions in the substrate.

18. A method as defined in claim 16 , further comprising forming source and drain regions in the substrate.

19. A method as defined in claim 1 , wherein the method comprises depositing three silicon atom layers and three group IIIA element atom layers.

20. A method as defined in claim 1 , wherein the semiconductor substrate comprises silicon.