Method of forming gettering layer

Patent metadata

Field	Value
Publication number	US-9721809-B2
Application number	US-201314029225-A
Country	US
Kind code	B2
Filing date	Sep 17, 2013
Priority date	Sep 20, 2012
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

Disclosed herein is a method of forming a gettering layer for capturing metallic ions on the back side of a semiconductor wafer formed with devices on the face side thereof. The method includes irradiating the back-side surface of the semiconductor wafer with a pulsed laser beam having a pulse width corresponding to a thermal diffusion length of 10 to 230 nm, to thereby form the gettering layer.

First claim

What is claimed is:

1. A method of forming a gettering layer configured to capture metallic ions on a back-side surface of a semiconductor wafer formed with a plurality of devices on a face-side surface thereof, the method comprising:
irradiating the back-side surface of the semiconductor wafer with a pulsed laser beam to form the gettering layer of a depth of 10 to 230 nm, wherein the gettering layer is formed from the same material as the remainder of the semiconductor wafer, wherein the semiconductor wafer is a silicon wafer, and a pulse width of the pulsed laser beam is set in the range from 1 to 500 ps, and
wherein a relation of v/h≦2d is established, where h (kHz) is the repetition frequency of the pulsed laser beam, v (mm/sec) is the feed rate of the pulsed laser beam, and d (micron) is the spot diameter of the pulsed laser beam.

2. The method of forming a gettering layer according to claim 1 , wherein the wavelength of the pulsed laser beam is set to be not more than 1,550 nm.

3. The method of forming a gettering layer according to claim 2 , wherein the wavelength of the pulsed laser beam is set to be not more than 1,064 nm.

4. The method of forming a gettering layer according to claim 1 , wherein the entire back-side surface of the semiconductor wafer is irradiated with the pulsed laser beam.

5. The method of claim 4 , wherein the irradiating is performed in a spiral pattern.

6. The method of claim 4 , wherein the irradiating is performed in a parallel line pattern.

7. The method of claim 1 , wherein the pulsed laser beam is passed through a condenser prior to irradiating the back-side surface of the semi-conductor wafer.

8. The method of claim 7 , wherein the condenser includes an objective lens.

9. The method of claim 8 , wherein said objective lens has a diameter that is approximately equal to the diameter of the semiconductor wafer.

10. The method of claim 7 , wherein the back-side surface of said semiconductor wafer is composed of silicon, and further wherein the back-side surface of said semiconductor wafer directly faces said condenser.

11. The method of claim 1 , wherein the feed rate is at least 1000 mm/sec.

12. The method of claim 1 , wherein the wavelength of the pulsed laser beam is set between about 515 nm and about 1,064 nm.

Assignees

• Disco Corp

Inventors

• Morikazu Hiroshi
• Hattori Nao

Classifications

• H10P36/03

  within silicon bodies · CPC title

• H10P34/42 Primary

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

• H10P36/00 Primary

  Gettering within semiconductor bodies · CPC title

• H01L21/322 Primary

  Electricity · mapped topic

• H01L21/268

  Electricity · mapped topic