Femtosecond laser-induced formation of submicrometer spikes on a semiconductor substrate

Patent metadata

Field	Value
Publication number	US-10361083-B2
Application number	US-201514836609-A
Country	US
Kind code	B2
Filing date	Aug 26, 2015
Priority date	Sep 24, 2004
Publication date	Jul 23, 2019
Grant date	Jul 23, 2019

Abstract

The present invention generally provides semiconductor substrates having submicron-sized surface features generated by irradiating the surface with ultra short laser pulses. In one aspect, a method of processing a semiconductor substrate is disclosed that includes placing at least a portion of a surface of the substrate in contact with a fluid, and exposing that surface portion to one or more femtosecond pulses so as to modify the topography of that portion. The modification can include, e.g., generating a plurality of submicron-sized spikes in an upper layer of the surface.

First claim

What is claimed is:

1. A method for processing a silicon substrate, comprising:
disposing a solid substance on a surface of a silicon substrate, wherein said solid substance comprises an electron-donating constituent,
placing said surface in contact with a liquid such that at least a portion of said liquid is in contact with said solid substance,
subsequently, irradiating said surface of the substrate with a plurality of laser pulses having a pulse width in a range of about 50 femtoseconds to about 500 femtoseconds in presence of said liquid on said surface so as to incorporate said electron-donating constituent of said solid substance as a plurality of inclusions within an upper layer of the substrate.

2. The method of claim 1 , wherein said electron-donating constituent is a sulfur-containing substance such that said inclusions comprise sulfur.

3. The method of claim 1 , wherein said solid substance comprises sulfur powder.

4. The method of claim 1 , wherein said liquid comprises an aqueous solution.

5. The method of claim 1 , wherein said liquid comprises any of water, alcohol, sulfuric acid and silicon oil.

6. The method of claim 1 , wherein said semiconductor substrate is any of a doped and undoped silicon wafer.

7. The method of claim 1 , wherein said laser pulses have a wavelength of less than or about 800 nm.

8. The method of claim 1 , wherein said upper layer has a thickness in a range of about 100 nm to about 1 micrometer.

9. The method of claim 1 , wherein the laser pulses are applied to a plurality of surface locations and wherein a number of the laser pulses applied to each surface location is in a range of 1 to about 2500.

10. The method of claim 1 , wherein placing said surface in contact with said liquid comprises disposing a layer of said liquid having a thickness in a range of about 1 mm to about 20 mm on said surface.

11. The method of claim 1 , wherein each of said laser pulses has an energy in a range of about 10 microjoules to about 400 microjoules.

Assignees

• Harvard College

Inventors

• Mazur Eric
• Shen Mengyan

Classifications

• H10P72/0422

  for wet etching · CPC title

• H10P50/00

  Etching of wafers, substrates or parts of devices · CPC title

• H10P32/1404

  using predeposition followed by drive-in of impurities into the semiconductor surface, e.g. predeposition from a gaseous phase · CPC title

• H10P32/171

  being group IV material · CPC title

• H10P14/3816

  Pulsed laser beam · CPC title