METHODS FOR PRODUCING UNIFORM LARGE-GRAINED AND GRAIN BOUNDARY LOCATION MANIPULATED POLYCRYSTALLINE THIN FILM SEMICONDUCTORS USING SEQUENTIAL LATERIAL SOLIDIFICATION

• US 20070202668A1
• Filed: 05/04/2007
• Published: 08/30/2007
• Est. Priority Date: 05/28/1996
• Status: Active Grant

• Current Assignee: James Im, Mark Crowder, Robert Sposili
• Original Assignee: James Im, Mark Crowder, Robert Sposili
• Inventors: Im, James, Sposili, Robert, Crowder, Mark
• Granted Patent: US 7,679,028 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 beamlets 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

1-6. -6. (canceled)

7. A system for processing a silicon thin film into a polycrystalline silicon thin film, comprising:

(a) an excimer laser for generating a plurality of excimer laser pulses of a predetermined fluence,

(b) an energy density modulator, optically coupled to said excimer laser, for controllably modulating said fluence of said excimer laser pulses emitted by said excimer laser;

(c) a beam homogenizer, optically coupled to said energy density modulator, for homogenizing said modulated laser pulses in a predetermined plane, said homogenized laser pulses each having a substantially predetermined size;

(d) a mask having one or more slits having a predetermined width, optically coupled to said beam homogenizer, for masking each said homogenized modulated laser pulse to generate one or more laser beamlets corresponding to each homogenized laser pulse, such that each beamlet has a shape defined by a length corresponding to the predetermined laser pulse size and a width corresponding to the slit width;

(e) a sample stage, optically coupled to said mask and adapted for translation, for receiving the one or more laser beamlets for each laser pulse to effect melting of a portion of any silicon thin film placed thereon corresponding to the shape of said laser beamlet; and

(f) a computer, coupled to said excimer laser and said energy density modulator, for controlling said controllable fluence modulation of said excimer laser pulses and relative positions of said sample stage and said mask, and for coordinating said excimer pulse generation and said fluence modulation with said relative positions of said sample stage and said mask, to thereby process said silicon thin film into a polycrystalline silicon thin film by sequential translation of said sample stage relative to said mask and irradiation of said thin film by one or more laser beamlets for each laser pulse at corresponding sequential locations thereon.

8. The system according to claim 7, wherein the mask is adapted for translation.

9. The system according to claim 7, wherein the system comprises instructions executable by a computer for:

(g) irradiating a silicon thin film with the laser beamlet to effect melting of a first portion of the thin film corresponding to the shape of the predefined slit pattern in the mask; and

(h) based on dimensions of the mask, translating at least one of the thin film and the excimer laser pulses relative to the other one of the thin film and the excimer laser pulse so as to reach a second location.

10. A system for processing a silicon thin film into a polycrystalline silicon thin film, comprising:

(a) a pulsed excimer laser for generating a plurality of excimer laser pulses;

each having a substantially predetermined size;

(b) a mask having one or more slits having a predetermined width, optically coupled to said pulsed excimer laser pulses, for masking each said laser pulse to generate one or more laser beamlets corresponding to each laser pulse, such that each beamlet has a shape defined by a length corresponding to the predetermined laser pulse size and a width corresponding to the slit width;

(c) a sample stage, optically coupled to said mask and adapted for translation, for receiving the one or more laser beamlets for each laser pulse to effect melting of a portion of any silicon thin film placed thereon corresponding to the shape of said laser beamlet;

(d) a computer, coupled to said excimer laser and said sample stage, for controlling said excimer laser pulses and relative positions of said sample stage and said mask, and for coordinating said excimer pulse generation with said relative positions of said sample stage and said mask; and

(e) instructions on a computer readable medium to thereby process said silicon thin film into a polycrystalline silicon thin film by sequential translation of said sample stage relative to said mask and irradiation of said thin film by one or more laser beamlets for each laser pulse at corresponding sequential locations thereon, wherein each of the irradiated portions is melted through a thickness of the thin film and a lateral growth is effectuated in each molten portion of the thin film.

11. The system according to claim 10, wherein the mask is adapted for translation.

12. The system according to claim 10, wherein the system comprises instructions executable by a computer for:

(g) irradiating a silicon thin film with the laser beamlet to effect melting of a first portion of the thin film corresponding to the shape of the predefined slit pattern in the mask; and

(h) based on dimensions of the mask, translating at least one of the thin film and the excimer laser pulses relative to the other one of the thin film and the excimer laser pulse so as to reach a second location.