Semiconductor manufacturing using optical ablation

• US 7,115,514 B2
• Filed: 10/01/2004
• Issued: 10/03/2006
• Est. Priority Date: 10/02/2003
• Status: Active Grant

• Current Assignee: Rayd LLC
• Original Assignee: Raydiance, Inc. (Coherent Corp.)
• Inventors: Stoltz, Richard
• Primary Examiner(s): Deo, Duy-Vu N.
• Assistant Examiner(s): Tran, Binh X.
• Application Number:
  US10/957,271
• Publication Number:
  US 20050074974A1
• Time in Patent Office: 732 Days
• Field of Search: 438/690, 438/940, 438/463
• US Class Current: 438/690
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: Y10S 438/94 Laser ablative material removal

Abstract

The present invention relates to methods and systems for ablation based material removal configuration for use in semiconductor manufacturing that includes the steps of generating an initial wavelength-swept-with-time optical pulse in an optical pulse generator, amplifying the initial pulse, compressing the amplified pulse to a duration of less than about 10 picoseconds and applying the compressed optical pulse to the wafer surface, to remove material from, e.g., wafer surface.

Claims

1. A method of removing material from a surface of a semiconductor wafer comprising the steps of:

generating an initial wavelength-swept-with-time optical pulse in an optical pulse generator;

amplifying the initial pulse;

compressing the amplified pulse to a duration of less than about 10 picoseconds, to generate a compressed optical pulse; and

applying the compressed optical pulse to the wafer surface, to remove material from the wafer surface;

wherein the step of amplifying is done with a fiber-amplifier and the step of compressing is done with an air-path between gratings compressor, and the initial wavelength-swept-with-time optical pulses is between about 10 picoseconds and about 3 nanoseconds and the compressed optical pulse has a sub-picosecond duration and an energy density on the surface is between about 2 and about 10 times an optical ablation threshold of the surface.

2. The method of claim 1, wherein the material removal is done in a line to give minimal-pressure ablation scribing, wherein stress-increasing scratching of the surface is reduced.

3. The method of claim 1, further comprising a step of sensing a composition of material being removed.

4. The method of claim 1, wherein the fiber amplifier is an erbium-doped fiber amplifier.

5. The method of claim 1, wherein the air-path between gratings compressor is a Treacy grating compressor.

6. The method of claim 1, wherein the compressing is done with a chirped fiber compressor.

7. A method of removing material from a surface of a semiconductor wafer comprising the steps of:

generating an initial wavelength-swept-with-time optical pulse in an optical pulse generator;

amplifying the initial pulse;

compressing the amplified pulse to a duration of less than about 10 picoseconds, to generate a compressed optical pulse; and

applying the compressed optical pulse to the wafer surface, to remove material from the wafer surface;

wherein pulse energy density and ablation rate are independently controlled.

8. The method of claim 7, wherein the wafer has a silicon, GaAs, or InP substrate.

9. The method of claim 7, wherein the amplifying is done with one or more fiber-amplifier, one or more semiconductor optical amplifier or combinations thereof.

10. The method of claim 7, wherein the material removal is used to replace a dry-etching step.

11. The method of claim 7, wherein the step of amplifying uses one or more optical amplifiers in a train mode.

12. The method of claim 7, wherein the compressed optical pulse is generally circular with an area of between about 1 and 50 micron in diameter when applied to the surface.

13. The method of claim 7, wherein two or more fiber amplifiers are used in a train mode and two or more fiber amplifiers are used with one compressor.

14. The method of claim 7, wherein the compressed optical pulse is scanned on the wafer surface using one or more piezoelectrically driven mirror.

15. The method of claim 7, wherein the material removal is done in a line to give ablation trench digging.

16. The method of claim 7, wherein the material includes copper or a noble metal.

17. The method of claim 7, further comprising a step of sensing a composition of material being removed.

18. The method of claim 17, wherein a composition of material being sensed is analyzed to determine when the material removal reaches an indication layer.

19. A method of removing material from a surface of a semiconductor wafer comprising the steps of:

generating an initial wavelength-swept-with-time optical pulse in an optical pulse generator;

amplifying the initial pulse;

compressing the amplified pulse to a duration of less than about 10 picoseconds, to generate a compressed optical pulse; and

applying the compressed optical pulse to the wafer surface, to remove material from the wafer surface;

wherein a pulse energy density, a fiber amplifier operating temperature and an ablation rate are independently controlled.