Liquid immersion doping

Patent metadata

Field	Value
Publication number	US-9805931-B2
Application number	US-201514838433-A
Country	US
Kind code	B2
Filing date	Aug 28, 2015
Priority date	Aug 28, 2015
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

Methods for processing of a workpiece are disclosed. A fluid that contains a desired dopant is prepared. The workpiece is immersed in this fluid, such that the dopant is able to contact all surfaces of the workpiece. The fluid is then evacuated, leaving behind the dopant on the workpiece. The dopant is then subjected to a thermal treatment to drive the dopant into the surfaces of the workpiece. In certain embodiments, a selective doping process may be performed by applying a mask to certain surfaces prior to immersing the workpiece in the fluid. In certain embodiments, the fluid may be in a super-critical state to maximize the contact between the dopant and the workpiece.

First claim

What is claimed is:

1. A method of doping a workpiece, comprising:
immersing the workpiece in super-critical fluid containing dopant;
removing the super-critical fluid from the workpiece, wherein residue of the dopant remains on exposed surfaces of the workpiece; and
applying a thermal treatment to drive the dopant into the workpiece, wherein the removing and the applying are performed at least partly simultaneously.

2. The method of claim 1 , further comprising applying a mask to portions of the workpiece prior to the immersing and removing the mask after removing the super-critical fluid.

3. The method of claim 1 , wherein the removing and the applying are performed using a laser.

4. The method of claim 1 , wherein the removing comprises changing pressure or temperature of the super-critical fluid to cause the super-critical fluid to change phase.

5. The method of claim 1 , wherein the super-critical fluid comprises water.

6. The method of claim 1 , wherein the dopant comprises boron, arsenic or phosphorus.

7. A method of doping a workpiece having a feature length of 5 nm or less, comprising:
immersing the workpiece in a gas containing a dopant, wherein the gas is compressed by increasing pressure or temperature so that a ratio of mean free path of the gas to the feature length is less than 1;
removing the gas, wherein residue of the dopant remains on exposed surfaces of the workpiece; and
performing a thermal treatment to drive the dopant into the workpiece, wherein the removing and the performing are performed at least partly simultaneously.

8. The method of claim 7 , wherein the ratio is less than 0.01.

9. The method of claim 7 , wherein the dopant is dissolved in the gas after the gas is compressed.

10. The method of claim 7 , further comprising applying a mask to portions of the workpiece prior to the immersing and removing the mask after removing the gas.

11. The method of claim 7 , wherein the removing and the applying are performed using a laser.

12. The method of claim 7 , wherein the gas comprises water.

13. The method of claim 7 , wherein the workpiece comprises silicon and the dopant comprises boron, arsenic or phosphorus.

14. A method of doping a workpiece having a predetermined feature length of 5 nm or less, comprising:
immersing the workpiece in a fluid having a ratio of a mean free path of the fluid to the predetermined feature length is less than 1, wherein the fluid contains a dopant;
removing the fluid from the workpiece by changing pressure or temperature, so that the fluid becomes a gas and wherein the dopant remains on exposed surfaces of the workpiece; and
performing a thermal treatment to drive the dopant into the workpiece, wherein the removing and the performing are performed at least partly simultaneously.

15. The method of claim 14 , wherein the fluid is a liquid.

16. The method of claim 14 , wherein the fluid is a super-critical fluid.

Assignees

• Varian Semiconductor Equipment Ass Inc

Inventors

• Sinclair Frank
• Scheuer Jay T
• Lee William Davis
• Kellerman Peter L

Classifications

• H10P34/42

  with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20) · CPC title

• H10P32/1408

  from or through or into an external applied layer, e.g. photoresist or nitride layers · CPC title

• H10P32/174

  being Group III-V material · CPC title

• H10P32/16

  between a solid phase and a liquid phase · CPC title

• H10P32/14

  within a single semiconductor body or layer in a solid phase; between different semiconductor bodies or layers, both in a solid phase · CPC title