Uniform large-grained and grain boundary location manipulated polycrystalline thin film semiconductors formed using sequential lateral solidification and devices formed thereon

Abstract

Methods for processing an amorphous silicon thin film sample into a polycrystalline silicon thin film are disclosed. One method includes generating a sequence of excimer laser pulses, controllably modulating each pulse to a predetermined fluence, homoginizing each modulated pulse in a predetermined plane, masking portions of each homoginized pulse with a 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 corresponding to each fluence controlled patterned beamlet pulse, and controllably sequentially translating a relative position of the sample with respect to each of the fluence controlled pulse of slit patterned beamlets.

1 . A system for processing a silicon thin film into a polycrystalline thin film, comprising:
 (a) an excimer laser for generating a plurality of excimer laser pulses of a predetermined fluence;   (b) a mask having one or more slits of a predetermined width, optically coupled to said excimer laser, for masking each of said laser pulses to generate one or more laser beamlets corresponding to each of said laser pulses, such that each beamlet has a shape defined by a length and a width, said width being determined by said predetermined slit width;   (c) a sample stage, optically coupled to said mask and adapted for translation and for holding said silicon thin film, for receiving said one or more laser beamlets for each of said homogenous laser pulses to effect melting of a portion of said silicon thin film corresponding to said shape of said laser beamlet; and   (d) a computer, coupled to said excimer laser, for controlling 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, 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 said one or more laser beamlets for each of said homogenized laser pulses at corresponding sequential locations therein.   
     
     
         2 . The system according to  claim 1 , wherein said mask is adapted for translation. 
     
     
         3 . The system according to  claim 1 , further comprising a beam homogenizer for homogenizing said laser pulses in a predetermined plane, said homogenized laser pulses each having a substantially predetermined size. 
     
     
         4 . The system according to  claim 1 , wherein said computer is adapted to controllably modulate said predetermined fluence of said excimer laser pulses. 
     
     
         5 . The system according to  claim 1 , further comprising a computer readable medium storing instructions executable by said computer for:
 (f) irradiating said silicon thin film with said laser beamlet to effect melting of a first portion of said silicon thin film corresponding to said shape of said predefined slit pattern in said mask; and   (g) based on dimensions of said mask, translating at least one of said thin film and said excimer laser pulses relative to the other so as to reach a second location.   
     
     
         6 . The system of  claim 1 , wherein said length corresponds to said predetermined size of said homogenized laser pulses. 
     
     
         7 . An apparatus for making a laterally extending crystalline region in a film of semiconductor material on a substrate having at least a surface region comprising a material which is different from said semiconductor material and which is inert with respect to crystal growth in said film, comprising:
 (a) a pulsed radiation beam source for providing a plurality of radiation beam pulses;   (b) a beam mask adapted to receive said plurality of laser beam pulses and for defining a plurality of masked laser beam pulses, each having an intensity pattern for irradiating said film;   (c) a sample translation stage optically coupled to said beam mask, and adapted for holding said substrate while at least a portion of said film is irradiated by said masked laser beam pulses and for translating said substrate in a lateral direction with respect to said masked laser beam pulses from a first position to at least a second position;   wherein when said sample translation stage is in said first position, a first portion of said semiconductor film is positioned to be irradiated by a first of said masked laser beam pulses so as to melt said semiconductor material in a first portion throughout its thickness, and when said sample translation stage is in said second position, a second portion of said semiconductor film is positioned to be irradiated by a second of said masked laser beam pulses so as to melt said semiconductor material in a second portion throughout its thickness, and   wherein said second portion overlaps said first portion such that at least one semiconductor crystal formed in said first portion as a result of said irradiating in said first position and subsequent solidification is in both said first portion and said second portion.   
     
     
         8 . The apparatus of  claim 7 , wherein said sample translation stage is further adapted for translating said substrate in a lateral direction with respect to said masked laser beam pulses from said second position to at least a third position;
 wherein when said sample translation stage is in said third position, a third portion of said semiconductor film is positioned to be irradiated by a third of said masked laser beam pulses so as to melt said semiconductor material in a third portion throughout its thickness, and   wherein said third portion overlaps said second portion such that at least one semiconductor crystal formed in said second portion as a result of said irradiating in said second position and subsequent solidification is in both said second portion and said third portion.   
     
     
         9 . The apparatus of  claim 7 , wherein said radiation beam pulses comprise laser beam pulses.