Systems and methods for inducing crystallization of thin films using multiple optical paths

• US 8,034,698 B2
• Filed: 10/16/2007
• Issued: 10/11/2011
• Est. Priority Date: 09/16/2003
• Status: Expired due to Fees

• Current Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Original Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Inventors: Im, James S.
• Primary Examiner(s): Smith; Zandra
• Assistant Examiner(s): Perkins; Pamela E
• Application Number:
  US11/873,038
• Publication Number:
  US 20080176414A1
• Time in Patent Office: 1,456 Days
• Field of Search: None
• US Class Current: 438/487
• CPC Class Codes: C30B 1/04 Isothermal recrystallisation
• CPC Class Codes: G03F 7/70041 by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control
• CPC Class Codes: G03F 7/70725 control
• CPC Class Codes: H01L 21/02488 Insulating materials
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02595 polycrystalline
• CPC Class Codes: H01L 21/02678 Beam shaping, e.g. using a mask
• CPC Class Codes: H01L 21/0268 Shape of mask
• CPC Class Codes: H01L 21/02683 Continuous wave laser beam
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 21/02691 Scanning of a beam
• CPC Class Codes: Y10T 117/10 Apparatus
• CPC Class Codes: Y10T 117/1004 with means for measuring, testing, or sensing
• CPC Class Codes: Y10T 117/1008 with responsive control means

Abstract

The present invention is directed to systems and methods for irradiating regions of a thin film sample(s) with laser beam pulses having different energy beam characteristics that are generated and delivered via different optical paths. An exemplary method includes generating laser beam pulses having energy beam characteristics, directing a first pulse onto a first optical path, modulating the pulse'"'"'s energy beam characteristics, and irradiating at least a portion of a first region of the thin film with the pulse to induce crystallization of the portion of the first region. The method also includes directing a second pulse onto a second optical path, modulating the pulse'"'"'s energy beam characteristics so as to be different from the energy beam characteristics of the first pulse, and irradiating at least a portion of a second region of the thin film with the second pulse to induce crystallization of the portion of the second region.

Claims

1. A method of processing a thin film, comprising:

(a) generating a plurality of laser beam pulses using a laser source having energy beam characteristics;

(b) directing a first generated laser beam pulse from the laser source onto a first optical path, wherein said first optical path includes at least one optical element;

(c) modulating said energy beam characteristics of said first optical path-directed laser beam pulse via said at least one optical element of said first optical path;

(d) irradiating at least a portion of a first region of said thin film with said first optical path-directed laser beam pulse to induce melting and a subsequent crystallization of said portion of said first region;

(e) directing a second generated laser beam pulse from the same laser source onto a second optical path, wherein said second optical path includes at least one optical element;

(f) modulating said energy beam characteristics of said second optical path-directed laser beam pulse via said at least one optical element of said second optical path, wherein said energy beam characteristics of said second optical path-directed laser beam pulse is different from said energy beam characteristics of said first optical path-directed laser beam pulse; and

(g) irradiating at least a portion of a second region of said thin film with said second optical path-directed laser beam pulse to induce melting and a subsequent crystallization of said portion of said second region.

2. The method of claim 1, further comprising:

repeating steps (b)-(d) until said melting and crystallization of said first region of said thin film is induced; and

repeating steps (e)-(g) until said melting and crystallization of said second region of said thin film is induced, wherein said first region of said thin film has a first grain structure and said second region of said thin film has a second grain structure.

3. The method of claim 2, wherein at least one of the first and second grain structures comprises an elongated, grain-boundary location controlled grain structure.

4. The method of claim 2, further comprising:

wherein the first laser beam pulse irradiates a first portion of said first region and, in

repeating steps (b)-(d), the second laser beam pulse irradiates a second portion of said first region at a preselected distance from said first portion of said first region; and

wherein a third laser beam pulse irradiates a first portion of said second region and, in repeating steps (e)-(g), a fourth laser beam pulse irradiates a second portion of said second region at a preselected distance from said first portion of said second region.

5. The method of claim 4, wherein said preselected distance from said first portion of said first region to said second portion of said first region is controlled by moving said thin film.

6. The method of claim 4, wherein said preselected distance from said first portion of said first region to said second portion of said first region is a distance less than the lateral crystal growth which is induced in said first portion by said first laser beam pulse.

7. The method of claim 1, wherein said laser irradiation of said first and second regions comprises a sequential lateral solidification process (SLS).

8. The method of claim 1, wherein said thin film comprises a semiconductor material.

9. The method of claim 1, wherein said first region comprises an integration region of said thin film.

10. The method of claim 9, wherein said second region comprises a pixel region of said thin film.

11. The method of claim 1, wherein said first optical path includes a first mask having a first masking pattern and said second optical path includes a second mask having a second masking pattern.

12. The method of claim 11, wherein said first masking pattern is configured to facilitate crystallization of said portion of said first region of a first preselected grain length or first grain orientation and said second masking pattern is configured to facilitate crystallization of said portion of said second region of a second preselected grain length or second grain orientation.

13. The method of claim 1, wherein said first optical path includes a first mask and a first projection lens and said second optical path includes a second mask and a second projection lens.

14. The method of claim 13, wherein said first optical path further includes a first variable-focus field lens and said second optical path further includes a second variable-focus field lens.

15. The method of claim 14, wherein said first optical path further includes a first attenuator and a first homogenizing lens element and said second optical path further includes a second attenuator and a second homogenizing lens element.

16. The method of claim 1, wherein said first and second generated laser beam pulses are generated by at least one of the following laser sources:

continuous wave laser, solid state laser and excimer laser.

17. The method of claim 1, wherein irradiation conditions of said first region and said second region are selected from those suitable for at least one of the following:

sequential laser solidification, excimer laser anneal and uniform grain structure crystallization.

18. The method of claim 17, wherein said irradiation conditions of said first region are suitable for sequential laser solidification and said irradiation conditions of said second regions are suitable for uniform grain structure crystallization.

19. The method of claim 1, wherein after crystallization the mobility of said at least a portion of said first region of said film is greater than the mobility of said at least a portion of said second region.

20. A method of processing a plurality of thin films, comprising:

(a) generating a plurality of laser beam pulses having energy beam characteristics;

(b) directing a generated laser beam pulse onto a first optical path, wherein said first optical path includes at least one optical element;

(c) modulating said energy beam characteristics of said first optical path-directed laser beam pulse via said at least one optical element of said first optical path;

(d) irradiating a portion of a region of a first thin film with said first optical path-directed laser beam pulse to induce melting and a subsequent crystallization of said portion of said region of said first thin film;

(e) directing a generated laser beam pulse onto a second optical path, wherein said second optical element includes at least one optical element;

(f) modulating said energy beam characteristics of said second optical path-directed laser beam pulse via said at least one optical element of said second optical path, wherein said energy beam characteristics of said second optical path-directed laser beam pulse is different from said energy beam characteristics of said first optical path-directed laser beam pulse; and

(g) irradiating a portion of a region of a second thin film with said second optical path-directed laser beam pulse to induce melting and a subsequent crystallization of said portion of said region of said second thin film.

21. The method of claim 20, further comprising:

(h) repeating steps (b)-(d) until said melting and crystallization of said region of said first thin film is induced; and

(i) repeating steps (e)-(g) until said melting and crystallization of said region of said second thin film is induced, wherein said region of said first thin film has a first grain structure and said region of said second thin film has a second grain structure.

22. The method of claim 21, further comprising:

(j) directing a generated laser beam pulse onto said second optical path;

(k) modulating said energy beam characteristics of said second optical path-directed laser beam pulse via said at least one optical element of said second optical path;

(l) irradiating a portion of another region of said first thin film with said second optical path-directed laser beam pulse to induce melting and a subsequent crystallization of said portion of said another region of said first thin film;

(m) directing a generated laser beam pulse onto said first optical path;

(n) modulating said energy beam characteristics of said first optical path-directed laser beam pulse via said at least one optical element of said first optical path, wherein said energy beam characteristics of said first optical path-directed laser beam pulse is different from said energy beam characteristics of said second optical path-directed laser beam pulse; and

(o) irradiating a portion of another region of said second thin film with said first optical path-directed laser beam pulse to induce melting and a subsequent crystallization of said portion of said another region of said second thin film.

23. The method of claim 22, further comprising:

(p) repeating steps (j)-(l) until said melting and crystallization of said another region of said first thin film is induced; and

(q) repeating steps (m)-(n) until said melting and crystallization of said another region of said second thin film is induced.