Methods for producing uniform large-grained and grain boundary location manipulated polycrystalline thin film semiconductors using sequential lateral solidification

• US 20030096489A1
• Filed: 11/13/2002
• Published: 05/22/2003
• Est. Priority Date: 09/03/1999
• Status: Active Grant

• Current Assignee: James S. Im, Mark A. Crowder, Robert S. Sposili
• Original Assignee: James S. Im, Mark A. Crowder, Robert S. Sposili
• Inventors: Sposili, Robert S., Im, James S., Crowder, Mark A.
• Granted Patent: US 7,029,996 B2
• Time in Patent Office: Days
• US Class Current: 438/487
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/0626 Energy control of the laser beam B23K26/0622 takes precedence
• CPC Class Codes: B23K 26/066 by using masks
• 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 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0268 Shape of mask
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 21/02691 Scanning of a beam
• CPC Class Codes: H01L 27/1285 using control of the annealing or irradiation parameters, e.g. using different scanning direction or intensity for different transistors
• CPC Class Codes: H01L 27/1296 adapted to increase the uniformity of device parameters
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30

Abstract

Methods for processing an amorphous silicon thin film sample into a polycrystalline silicon thin film are disclosed. In one preferred arrangement, a method includes the steps of generating a sequence of excimer laser pulses, controllably modulating each excimer laser pulse in the sequence to a predetermined fluence, homoginizing each modulated laser pulse in the sequence in a predetermined plane, masking portions of each homoginized fluence controlled laser pulse in the sequence with a two dimensional pattern of slits to generate a sequence of fluence controlled pulses of line patterned beamlets, each slit in the pattern of slits being sufficiently narrow to prevent inducement of significant nucleation in region of a silicon thin film sample irradiated by a beamlet corresponding to the slit, irradiating an amorphous silicon thin film sample with the sequence of fluence controlled slit patterned beamilets to effect melting of portions thereof corresponding to each fluence controlled patterned beamlet pulse in the sequence of pulses of patterned beamlets, and controllably sequentially translating a relative position of the sample with respect to each of the fluence controlled pulse of slit patterned beamlets to thereby process the amorphous silicon thin film sample into a single or polycrystalline silicon thin film

Claims

1. A method for processing an amorphous silicon thin film sample into a polycrystalline silicon thin film, comprising the steps of:

(a) generating a sequence of excimer laser pulses;

(b) controllably modulating each excimer laser pulse in said sequence to a predetermined fluence;

(c) homoginizing each modulated laser pulse in said sequence in a predetermined plane;

(d) masking portions of each homoginized fluence controlled laser pulse in said sequence with a two dimensional pattern of slits to generate a sequence of fluence controlled pulses of line patterned beamlets, each slit in said pattern of slits being sufficiently narrow to prevent inducement of significant nucleation in region of a silicon thin film sample irradiated by a beamlet corresponding to said slit,

(e) irradiating an amorphous silicon thin film sample with said sequence of fluence controlled slit patterned beamlets to effect melting of portions thereof corresponding to each fluence controlled patterned beamlet pulse in said sequence of pulses of patterned beamlets; and

(f) controllably sequentially translating a relative position of said sample with respect to each of said fluence controlled pulse of slit patterned beamlets to thereby process said amorphous silicon thin film sample into a single or polycrystalline silicon thin film.

2. The method of claim 1, wherein said masking step comprises masking portions of each homoginized fluence controlled laser pulse in said sequence with a two dimensional pattern of substantially parallel straight slits spaced a predetermined distance apart and linearly extending parallel to one direction of said plane of homoginization to generate a sequence of fluence controlled pulses of slit patterned beamlets.

3. The method of claim 2, wherein said translating step comprises controllably sequentially translating said relative position of said sample in a direction perpendicular to each of said fluence controlled pulse of slit patterned beamlets over substantially said predetermined slit spacing distance, to the to thereby process said amorphous silicon thin film sample into polycrystalline silicon thin film having long grained, directionally controlled crystals.

4. The method of claim 1, wherein:

(a) said masking step comprises masking portions of each homoginized fluence controlled laser pulse in said sequence with a two dimensional pattern of substantially parallel straight slits of a predetermined width, spaced a predetermined distance being less than said predetermined width apart, and linearly extending parallel to one direction of said plane of homoginization to generate a sequence of fluence controlled pulses of slit patterned beamlets; and

(b) said translating step comprises translating by a distance less than said predetermined width said relative position of said sample in a direction perpendicular to each of said fluence controlled pulse of slit patterned beamlets, to the to thereby process said amorphous silicon thin film sample into polycrystalline silicon thin film having long grained, directionally controlled crystals using two laser pulses.

5. The method of claim 4, wherein said predetermined width is approximately 4 micrometers, said predetermined spacing distance is approximately 2 micrometers, and said translating distance is approximately 3 micrometers.

6. The method of claim 1, wherein said masking step comprises masking portions of each homoginized fluence controlled laser pulse in said sequence with a two dimensional pattern of substantially parallel straight slits spaced a predetermined distance apart and linearly extending at substantially 45 degree angle with respect to one direction of said plane of homoginization to generate a sequence of fluence controlled pulses of slit patterned beamlets.

7. The method of claim 6, wherein said translating step comprises controllably sequentially translating said relative position of said sample in a direction parallel to said one direction of said plane of homoginization over substantially said predetermined slit distance, to thereby process said amorphous silicon thin film sample into polycrystalline silicon thin film having long grained, directionally controlled crystals that are disoriented with respect to the XY axis of the thin silicon film.

8. The method of claim 1, wherein:

(a) said masking step comprises masking portions of each homoginized fluence controlled laser pulse in said sequence with a two dimensional pattern of substantially parallel straight slits of a predetermined width, spaced a predetermined distance being less than said predetermined width apart, and linearly extending at substantially 45 degree angle with respect to one direction of said plane of homoginization to generate a sequence of fluence controlled pulses of slit patterned beamlets; and

(b) said translating step comprises translating by a distance less than said predetermined width said relative position of said sample in a direction parallel to said one direction of said plane of homoginization, to the to thereby process said amorphous silicon thin film sample into polycrystalline silicon thin film having long grained, directionally controlled crystals that are disoriented with respect to the XY axis of the thin silicon film using two laser pulses.

9. The method of claim 8, wherein said predetermined width is approximately 4 micrometers, said predetermined spacing distance is approximately 2 micrometers, and said translating distance is approximately 3 micrometers.

10. The method of claim 1, wherein said masking step comprises masking portions of each homoginized fluence controlled laser pulse in said sequence with a two dimensional pattern of intersecting straight slits, a first group of straight slits being spaced a first predetermined apart and linearly extending at substantially 45 degree angle with respect to a first direction of said plane of homoginization, and a second group of straight slits being spaced a second predetermined distance apart and linearly extending at substantially 45 degree angle with respect to a second direction of said plane of homoginization and intersecting said first group at substantially a 90 degree angle, to generate a sequence of fluence controlled pulses of slit patterned beamlets.

11. The method of claim 10, wherein said translating step comprises controllably sequentially translating said relative position of said sample in a direction parallel to said first direction of said plane of homoginization over substantially said first predetermined slit spacing distance, to thereby process said amorphous silicon thin film sample into polycrystalline silicon thin film having large diamond shaped crystals.

12. The method of claim 1, wherein said masking step comprises masking portions of each homoginized fluence controlled laser pulse in said sequence with a two dimensional pattern of sawtooth shaped slits spaced a predetermined distance apart and extending generally parallel to one direction of said plane of homoginization to generate a sequence of fluence controlled pulses of slit patterned beamlets.

13. The method of claim 12, wherein said translating step comprises controllably sequentially translating said relative position of said sample in a direction perpendicular to each of said fluence controlled pulse of slit patterned beamlets over substantially said predetermined slit spacing distance, to the to thereby process said amorphous silicon thin film sample into polycrystalline silicon thin film having large hexagonal crystals.

14. A method for processing an amorphous silicon thin film sample into a polycrystalline silicon thin film, comprising the steps of:

(a) generating a sequence of excimer laser pulses;

(b) homoginizing each laser pulse in said sequence in a predetermined plane;

(c) masking portions of each homoginized laser pulse in said sequence with a two dimensional pattern of substantially opaque dots to generate a sequence of pulses of dot patterned beamlets;

(d) irradiating an amorphous silicon thin film sample with said sequence of dot patterned beamlets to effect melting of portions thereof corresponding to each dot patterned beamlet pulse in said sequence of pulses of patterned beamlets; and

(e) controllably sequentially translating said sample relative to each of said pulses of dot patterned beamlets by alternating a translation direction in two perpendicular axis and in a distance less than the super lateral grown distance for said sample, to thereby process said amorphous silicon thin film sample into a polycrystalline silicon thin film.