Method for Manufacturing Simox Wafer

Abstract

A SIMOX wafer having a BOX layer with a thin film thickness is obtained without a reduction in productivity or deterioration in quality. In a method for manufacturing a SIMOX wafer comprising: a step of forming a first ion-implanted layer in a silicon wafer; a step of forming a second ion-implanted layer that is in an amorphous state; and a high-temperature heat treatment step of maintaining the wafer in an oxygen contained atmosphere at a temperature that is not lower than 1300° C. but less than a silicon melting point for 6 to 36 hours to change the first and the second ion-implanted layers into a BOX layer, a gas containing chlorine that is not less than 0.1 volume % but less than 1.0 volume % is mixed into an atmosphere during temperature elevation in the high-temperature heat treatment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a method for manufacturing a SIMOX wafer according to an embodiment of the present invention in the step order;

FIG. 2 is a view showing a change in the wafer when a high-temperature heat treatment according to the present invention is applied; and

FIG. 3 is a view showing a profile of a temperature and a time corresponding to FIGS. 1(a) to 1(d).

Claims

1. A method for manufacturing a SIMOX wafer comprising the following sequential steps: forming a first ion-implanted layer at a first depth in a silicon wafer by heating the wafer at a temperature in the range from 200 to 600° C. and implanting oxygen ions from a surface of wafer at the rate of 5×1016 to 3×1017 atoms/cm2;cooling the wafer to a temperature in the range from room temperature to 200° C. and implanting oxygen ions from the surface of the wafer at the rate of 1×1014 to 1×1016 atoms/cm2 to form a second ion-implanted layer that is in an amorphous state at a second depth in the wafer such that the second ion-implanted layer becomes continuous with the first ion-implanted layer on a front surface side of the wafer; andwherein the wafer is elevated to a temperature that is not lower than 130° ° C. but less than the melting point of silicon while maintaining the wafer in an atmosphere containing oxygen and a gas containing chlorine that is not less than 1.0 volume % mixed therewith during elevation of the temperature and maintaining the temperature for 6 to 36 hours to change the first and the second ion-implanted layers into a BOX layer.

2. The method of claim 1 wherein the temperature during formation of the first ion-implanted layer is in the range from 300 to 500° C.

3. The method of claim 1 wherein the oxygen ions are implanted at the rate of 1×1017 to 1.5×1017 atoms/cm2 to form the first ion-implanted layer.

4. The method of claim 1 wherein an implantation energy of from 40 to 220 keV is used for the ion implantation step to form the first ion-implanted layer.

5. The method of claim 4 wherein implantation energy of from 140 to 180 keV is used for the ion implantation step to form the first ion-implanted layer.

6. The method of claim 1 wherein the first ion-implanted layer is implanted at a first depth of 100 to 600 nm from the surface in parallel with the wafer surface.

7. The method of claim 6 wherein the first ion implanted layer is implanted at a first depth of 300 to 400 nm from the surface in parallel with the wafer surface.

8. The method of claim 1 wherein the wafer is cooled to between 20 to 30° C.

9. The method of claim 1 wherein the oxygen ion are implanted at the rate of 1×1015 to 1.5×1016 atoms/cm2 to form the second ion-implanted layer.

10. The method of claim 1 wherein implantation energy of from 140 to 180 keV is used to form the second ion-implanted layer.

11. The method of claim 1 wherein the second ion-implanted layer is formed at a depth of 100 to 400 nm from the wafer surface between the first ion-implanted layer and the wafer surface and in parallel with the wafer surface.

12. The method of claim 1 wherein the second ion-implanted layer is formed at a depth of 300 to 400 nm from the wafer surface between the first ion-implanted layer and the wafer surface and in parallel with the wafer surface.

13. The method of claim 1 wherein the temperature is elevated to between 1320 and 1350° C.

14. The method of claim 1 wherein the wafer is maintained at a temperature not lower than 1300° C. but less than the melting point of silicon for from 12 to 24 hours.

15. The method of claim 1 wherein the volume of the gas containing chlorine is between 0.1 to 1.0 volume %.

16. The method of claim 1 wherein the gas containing chlorine is selected from the group consisting of HCl, Cl2, trichloroethylene, and trichloroethane.

17. The method of claim 1 wherein the gas containing chlorine is mixed into a mixed atmosphere of an inert gas.

18. The method of claim 16 wherein the amount of gas containing chlorine is from 0.2 to 0.5 volume %.

19. The method of claim 16 wherein the inert gas is argon or a nitride containing oxygen.

20. The method of claim 1 wherein after the temperature elevation, the atmosphere is an oxidizing atmosphere of an oxygen gas having a content of from 5.0 to 100.0%.

21. The method of claim 19 wherein after the temperature elevation, the atmosphere is an oxidizing atmosphere of an oxygen gas having a content of from 10 to 50 volume %.

22. A SIMOX wafer prepared by the method of claim 1.