High-efficiency line-forming optical systems and methods for defect annealing and dopant activation

Patent metadata

Field	Value
Publication number	US-9711361-B2
Application number	US-201715437055-A
Country	US
Kind code	B2
Filing date	Feb 20, 2017
Priority date	Nov 24, 2014
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

High-efficiency line-forming optical systems and methods for defect annealing and dopant activation are disclosed. The system includes a CO 2 -based line-forming system configured to form at a wafer surface a first line image having between 2000 W and 3000 W of optical power. The line image is scanned over the wafer surface to locally raise the temperature up to a defect anneal temperature. The system can include a visible-wavelength diode-based line-forming system that forms a second line image that can scan with the first line image to locally raise the wafer surface temperature from the defect anneal temperature to a spike anneal temperature. Use of the visible wavelength for the spike annealing reduces adverse pattern effects and improves temperature uniformity and thus annealing uniformity.

First claim

What is claimed is:

1. A method of performing defect annealing at a defect anneal temperature T D of a semiconductor wafer having a surface that includes a pattern, comprising:
forming from a CO 2 laser a light beam having a wavelength of nominally 10.6 microns and a first intensity profile with a Gaussian distribution in at least a first direction;
passing at least 50% of the light beam in the first direction to form first transmitted light;
focusing the first transmitted light at an intermediate focal plane to define a second intensity profile having a central peak and first side peaks immediately adjacent the central peak;
truncating the second intensity profile within each of the first side peaks to define second transmitted light that forms on the wafer surface a first line image having between 2000 W and 3000 W of optical power and an intensity uniformity of within +/−5% over a first line length in the range from 5 mm to 100 mm; and
scanning the first line image over the wafer surface to locally raise a temperature of the wafer surface to the defect anneal temperature T D .

2. The method according to claim 1 , wherein the defect anneal temperature T D is in the range 650° C.≦T D ≦1100° C.

3. The method according to claim 1 , further including performing spike annealing at a spike anneal temperature by:
forming a second line image at the wafer surface using a second light beam having a visible wavelength, wherein the second line image at least partially overlaps the first line image; and
scanning the second line image to locally raise the temperature of the wafer surface from the defect anneal temperature to the spike anneal temperature T A .

4. The method according to claim 3 , wherein the spike anneal temperature T A is in the range 1150° C.≦T A ≦1350° C.

5. The method according to claim 3 , wherein the first line image has a first width and the second line image has a second width that is between 5% and 25% of the first width.

6. The method according to claim 3 , wherein the first width is in the range from 25 microns to 1 mm.

7. The method according to claim 3 , including forming the second light beam using a laser diode light source and line-forming optics operably arranged relative thereto.

8. The method according to claim 3 , wherein the second wavelength is between 500 nm and 1000 nm.

9. The method according to claim 3 , wherein the second line image has a second line length in the range between 5 mm and 100 mm and an intensity uniformity of within +/−5%.

10. The method according to claim 3 , wherein the wafer surface temperature has a variation from the spike anneal temperature due to pattern effects, and wherein the variation is no more than 60° C.

11. A method of performing defect annealing of a semiconductor wafer having a surface with a pattern and a defect anneal temperature, comprising:
a) emitting an initial light beam from a CO 2 laser source, wherein the initial light beam has a wavelength of 10.6 microns;
b) passing the initial light beam through a beam-conditioning optical system to form a conditioned light beam having a first intensity profile with a Gaussian distribution in at least a first direction;
c) truncating the first intensity profile of the conditioned light beam using a first slit aperture to define first transmitted light that constitutes at least 50% of the conditioned light beam;
d) using a relay optical system, relaying the first transmitted light to an object plane that also defines an intermediate focal plane at which is operably disposed a second slit aperture, the relay optical system defining at the intermediate focal plane a second intensity profile having a central peak and first side peaks immediately adjacent the central peak;
e) using the second slit aperture, truncating the second intensity profile in the first direction and within each of the first side peaks to define second transmitted light;
f) using the relay optical system, forming form the second transmitted light a first line image at the wafer surface, wherein the first line image includes between 2000 W and 3000 W of optical power, has a first length in the range from 5 mm to 100 mm, and has an intensity uniformity of within +/−5%; and
g) scanning the first line image over the wafer surface to locally raise a temperature of the wafer surface to the defect anneal temperature.

12. The method according to claim 11 , wherein the act g) of scanning comprises supporting the wafer on a chuck and moving the chuck relative to the first line image.

13. The method according to claim 12 , further comprising using the chuck to heat the wafer.

14. The method according to claim 11 , wherein the defect anneal temperature is in the range from 650° C. to 1100° C.

15. The method according to claim 11 , further comprising:
generating a visible light beam;
forming from the visible light beam a second line image at the wafer surface that at least partially overlaps the first line image and that scans with the first line image to locally raise the temperature of the wafer surface from the defect annealing temperature to a spike anneal temperature, and wherein the second line image has an intensity variation of within +/−5%; and
wherein the wafer surface temperature has a variation from the spike anneal temperature due to pattern effects from the pattern on the surface of the semiconductor wafer, and wherein said variation is no more than 60° C.

16. The method according to claim 15 , further comprising using a diode-based line-forming optical system to generate the visible light beam and to form the second line image.

17. The method according claim 15 , wherein the spike anneal temperature is in the range from 1150° C. to 1350° C.

18. The method according to claim 15 , wherein the first and second line images have respective first and second widths, and wherein the second width is in the range from 5% to 25% of the first width.

19. The method according to claim 11 , wherein each first side peak is defined by a maximum value MX and first and second minimum values m1 and m2, wherein the second minimum value m2 is farther from the central peak than the first minimum value m1, and wherein the second slit aperture is configured to truncate the second intensity profile between the maximum value MX and the second minimum value m2 in each first side peak.

20. The method according to claim 11 , wherein the optical relay system comprises reflective optical components.

Assignees

• Ultratech Inc

Inventors

• Hawryluk Andrew M
• Anikitchev Serguei

Classifications

• H10P95/90

  Thermal treatments, e.g. annealing or sintering · CPC title

• H10P34/42 Primary

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

• H10P72/0436

  mainly by radiation · CPC title

• H01L21/2636

  Electricity · mapped topic

• B23K26/066

  by using masks · CPC title