Laser irradiation apparatus and method for manufacturing semiconductor device

Abstract

It is an object of the present invention to provide a laser irradiation apparatus being able to irradiate the irradiation object with the laser beam having homogeneous energy density without complicating the optical system. The laser irradiation apparatus of the present invention comprises a laser oscillator, an optical system for scanning repeatedly a beam spot of the laser beam emitted from the laser oscillator in a uniaxial direction over the surface of the irradiation object, and a position controlling means for moving the position of the irradiation object relative to the laser beam in a direction perpendicular to the uniaxial direction.

1 . A laser irradiation apparatus comprising: 
 a laser oscillator;    an optical system for forming a quasi-linear beam spot by scanning a laser beam emitted from the laser oscillator so as to move back and forth along a straight line; and    means for moving a position of an irradiation object relative to the laser beam in a direction which intersects a major axis of the quasi-linear beam spot;    wherein the irradiation object is moved by the means so that a first irradiation region irradiated with the quasi-linear beam spot partly overlaps a second irradiation region irradiated with the quasi-linear beam spot after the first irradiation region is irradiated, and    wherein a position of the quasi-linear beam spot is moved by the means from the first irradiation region to the second irradiation region before the first irradiation region is completely solidified.    
   
   
       2 . The laser irradiation apparatus according to  claim 1 , 
 wherein the optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       3 . The laser irradiation apparatus according to  claim 1 , 
 wherein the laser beam is scanned faster by the optical system than the irradiation object is moved by the means.    
   
   
       4 . The laser irradiation apparatus according to  claim 1 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       5 . The laser irradiation apparatus according to  claim 1 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       6 . A laser irradiation apparatus comprising: 
 a laser oscillator;    an optical system for scanning a laser beam emitted from the laser oscillator so as to move back and forth along a straight line; and    means for moving a position of an irradiation object relative to the laser beam in a direction which intersects a scanning direction of the laser beam;    wherein the laser beam is scanned along a wave-like line or a saw-like line over the irradiation object by the optical system and the means,    wherein when the laser beam is scanned along the wave-like line or the saw-like line from a first direction-turning point to a third direction-turning point through a second direction-turning point, a first beam spot irradiating the first direction-turning point partly overlaps a second beam spot irradiating the third direction-turning point, and    wherein the laser beam is scanned from the first direction-turning point to the third direction-turning point before the irradiation object irradiated with the first beam spot is completely solidified.    
   
   
       7 . The laser irradiation apparatus according to  claim 6 , 
 wherein the optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       8 . The laser irradiation apparatus according to  claim 6 , 
 wherein the laser beam is scanned faster by the optical system than the irradiation object is moved by the means.    
   
   
       9 . The laser irradiation apparatus according to  claim 6 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       10 . The laser irradiation apparatus according to  claim 6 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       11 . A laser irradiation apparatus comprising: 
 a laser oscillator;    an optical system for scanning a laser beam emitted from the laser oscillator so as to move back and forth along a straight line; and    means for moving a position of an irradiation object relative to the laser beam in a direction which intersects a scanning direction of the laser beam;    wherein the laser beam is scanned along a plurality of straight lines arranging at uniform intervals by the optical system and the means,    wherein a first irradiation region irradiated with the laser beam along a first straight line among the straight lines partly overlaps a second irradiation region irradiated with the laser beam along a second straight line adjacent to the first straight line, and    wherein the second irradiation region is irradiated with the laser beam before the first irradiation region is completely solidified.    
   
   
       12 . The laser irradiation apparatus according to  claim 11 , 
 wherein the optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       13 . The laser irradiation apparatus according to  claim 11 , 
 wherein the laser beam is scanned faster by the optical system than the irradiation object is moved by the means.    
   
   
       14 . The laser irradiation apparatus according to  claim 11 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       15 . The laser irradiation apparatus according to  claim 11 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       16 . A laser irradiation apparatus comprising: 
 a laser oscillator;    an optical system for scanning a laser beam emitted from the laser oscillator so as to move back and forth along a straight line; and    means for moving a position of an irradiation object relative to the laser beam in a direction which intersects a scanning direction of the laser beam;    wherein the laser beam is scanned along a wave-like line or a saw-like line over the irradiation object by the optical system and the means,    wherein when the laser beam is scanned along the wave-like line or the saw-like line from a first direction-turning point to a third direction-turning point through a second direction-turning point, a first beam spot irradiating the first direction-turning point partly overlaps a second beam spot irradiating the third direction-turning point, and    wherein the laser beam is scanned from the first direction-turning point to the third direction-turning point within 100 ns.    
   
   
       17 . The laser irradiation apparatus according to  claim 16 , 
 wherein the optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       18 . The laser irradiation apparatus according to  claim 16 , 
 wherein the laser beam is scanned faster by the optical system than the irradiation object is moved by the means.    
   
   
       19 . The laser irradiation apparatus according to  claim 16 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       20 . The laser irradiation apparatus according to  claim 16 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       21 . A laser irradiation apparatus comprising: 
 a laser oscillator;    an optical system for scanning a laser beam emitted from the laser oscillator so as to move back and forth along a straight line; and    means for moving a position of an irradiation object relative to the laser beam in a direction which intersects a scanning direction of the laser beam;    wherein the laser beam is scanned along a plurality of straight lines arranging at uniform intervals by the optical system and the means,    wherein a first irradiation region formed by scanning the irradiation object with the laser beam along a first straight line among the straight lines partly overlaps a second irradiation region formed by scanning the irradiation object with the laser beam along a second straight line adjacent to the first straight line, and    wherein the laser beam is scanned from the first irradiation region to the second irradiation region within 100 ns.    
   
   
       22 . The laser irradiation apparatus according to  claim 21 , 
 wherein the optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       23 . The laser irradiation apparatus according to  claim 21 , 
 wherein the laser beam is scanned faster by the optical system than the irradiation object is moved by the means.    
   
   
       24 . The laser irradiation apparatus according to  claim 21 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       25 . The laser irradiation apparatus according to  claim 21 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       26 . A laser irradiation apparatus comprising: 
 a laser oscillator; and    an optical system for scanning a laser beam emitted from the laser oscillator along a plurality of straight lines arranging at uniform intervals;    wherein a first quasi-linear beam spot formed by scanning the laser beam along a first straight line among the straight lines partly overlaps a second quasi-linear beam spot formed by scanning the laser beam along a second straight line adjacent to the first straight line, and    wherein the second quasi-linear beam spot is formed by scanning the laser beam before an irradiation region irradiated with the first quasi-linear beam spot is completely solidified.    
   
   
       27 . The laser irradiation apparatus according to  claim 26 , 
 wherein the optical system comprises a first optical system for scanning the laser beam in a first direction and a second optical system for scanning the laser beam in a direction which intersects the first direction.    
   
   
       28 . The laser irradiation apparatus according to  claim 26 , 
 wherein each of the first optical system and the second optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       29 . The laser irradiation apparatus according to  claim 26  further comprising: 
 means for moving a position of the irradiation object relative to the laser beam.    
   
   
       30 . The laser irradiation apparatus according to  claim 26 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       31 . The laser irradiation apparatus according to  claim 26 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       32 . A laser irradiation apparatus comprising: 
 a laser oscillator; and    an optical system for scanning a laser beam emitted from the laser oscillator along a plurality of straight lines arranging at uniform intervals;    wherein a first quasi-linear beam spot formed by scanning the laser beam along a first straight line among the straight lines partly overlaps a second quasi-linear beam spot formed by scanning the laser beam along a second straight line adjacent to the first straight line, and    wherein the second quasi-linear beam spot begins to be formed by scanning the laser beam before an irradiation region irradiated with the first quasi-linear beam spot is completely solidified.    
   
   
       33 . The laser irradiation apparatus according to  claim 32 , 
 wherein the optical system comprises a first optical system for scanning the laser beam in a first direction and a second optical system for scanning the laser beam in a direction which intersects the first direction.    
   
   
       34 . The laser irradiation apparatus according to  claim 32 , 
 wherein each of the first optical system and the second optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       35 . The laser irradiation apparatus according to  claim 32  further comprising: 
 means for moving a position of the irradiation object relative to the laser beam.    
   
   
       36 . The laser irradiation apparatus according to  claim 32 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       37 . The laser irradiation apparatus according to  claim 32 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       38 . A laser irradiation apparatus comprising: 
 a laser oscillator; and    an optical system for scanning a laser beam emitted from the laser oscillator along a plurality of straight lines arranging at uniform intervals;    wherein a first quasi-linear beam spot formed by scanning the laser beam along a first straight line among the straight lines partly overlaps a second quasi-linear beam spot formed by scanning the laser beam along a second straight line adjacent to the first straight line, and    wherein the second quasi-linear beam spot is formed within 100 ns after forming the first quasi-linear beam spot.    
   
   
       39 . The laser irradiation apparatus according to  claim 38 , 
 wherein the optical system comprises a first optical system for scanning the laser beam in a first direction and a second optical system for scanning the laser beam in a direction which intersects the first direction.    
   
   
       40 . The laser irradiation apparatus according to  claim 38 , 
 wherein each of the first optical system and the second optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       41 . The laser irradiation apparatus according to  claim 38  further comprising: 
 means for moving a position of the irradiation object relative to the laser beam.    
   
   
       42 . The laser irradiation apparatus according to  claim 38 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       43 . The laser irradiation apparatus according to  claim 38 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       44 . A laser irradiation apparatus comprising: 
 a laser oscillator; and    an optical system for scanning a laser beam emitted from the laser oscillator along a wave-like line or a saw-like line;    wherein when the laser beam is scanned along the wave-like line or the saw-like line from a first direction-turning point to a third direction-turning point through a second direction-turning point, a first beam spot centering on the first direction-turning point partly overlaps a second beam spot centering on the third direction-turning point, and    wherein the laser beam is scanned from the first direction-turning point to the third direction-turning point before an irradiation region irradiated with the first beam spot is completely solidified.    
   
   
       45 . The laser irradiation apparatus according to  claim 44 , 
 wherein the optical system comprises a first optical system for scanning the laser beam in a first direction and a second optical system for scanning the laser beam in a direction which intersects the first direction.    
   
   
       46 . The laser irradiation apparatus according to  claim 44 , 
 wherein each of the first optical system and the second optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       47 . The laser irradiation apparatus according to  claim 44  further comprising: 
 means for moving a position of the irradiation object relative to the laser beam.    
   
   
       48 . The laser irradiation apparatus according to  claim 44 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       49 . The laser irradiation apparatus according to  claim 44 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       50 . A laser irradiation apparatus comprising: 
 a laser oscillator; and    an optical system for scanning a laser beam emitted from the laser oscillator along a wave-like line or a saw-like line;    wherein when the laser beam is scanned along the wave-like line or the saw-like line from a first direction-turning point to a third direction-turning point through a second direction-turning point, a first beam spot centering on the first direction-turning point partly overlaps a second beam spot centering on the third direction-turning point, and    wherein the laser beam is scanned from the first direction-turning point to the third direction-turning point within 100 ns.    
   
   
       51 . The laser irradiation apparatus according to  claim 50 , 
 wherein the optical system comprises a first optical system for scanning the laser beam in a first direction and a second optical system for scanning the laser beam in a direction which intersects the first direction.    
   
   
       52 . The laser irradiation apparatus according to  claim 50 , 
 wherein each of the first optical system and the second optical system is an acousto-optic element, a polygon mirror, or a resonant scanner.    
   
   
       53 . The laser irradiation apparatus according to  claim 50  further comprising: 
 means for moving a position of the irradiation object relative to the laser beam.    
   
   
       54 . The laser irradiation apparatus according to  claim 50 , 
 wherein the laser oscillator is a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       55 . The laser irradiation apparatus according to  claim 50 , 
 wherein the laser oscillator is a continuous wave laser oscillator.    
   
   
       56 . A method of manufacturing a semiconductor device comprising: 
 first scanning a first region of a semiconductor film with a laser beam along a first direction to melt the first region; and    second scanning a second region of the semiconductor film with the laser beam along a second direction to melt the second region, after scanning the first region,    wherein the first region partly overlaps the second region and at least a portion of the first region is in a molten state during scanning the second region with the laser beam.    
   
   
       57 . The method of manufacturing a semiconductor device according to  claim 56 , 
 wherein a crystal grows continuously from the first region to the second region through a region in which the first region overlaps the second region.    
   
   
       58 . The method of manufacturing a semiconductor device according to  claim 56 , 
 wherein when a part of the second region is irradiated with the laser beam, a part of the first region overlapped with the second region is in a molten state at least partly due to the first scanning of the first region with the laser beam.    
   
   
       59 . The method of manufacturing a semiconductor device according to  claim 56 , 
 wherein the first region and the second region have a linear shape, and    wherein the first direction is the same as the second direction and the first region partly overlaps the second region along the first direction.    
   
   
       60 . The method of manufacturing a semiconductor device according to  claim 56 , 
 wherein the laser beam is emitted from a continuous wave laser oscillator.    
   
   
       61 . The method of manufacturing a semiconductor device according to  claim 56 , 
 wherein the laser beam is emitted from a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       62 . A method of manufacturing a semiconductor device comprising: 
 crystallizing a semiconductor film by irradiating the semiconductor film with a laser beam;    wherein the semiconductor film is scanned with the laser beam along a wave-like line or a saw-like line;    wherein when the laser beam is scanned along the wave-like line or the saw-like line from a first direction-turning point to a third direction-turning point through a second direction-turning point, a first beam spot centering on the first direction-turning point partly overlaps a second beam spot centering on the third direction-turning point; and    wherein the second beam spot is formed by scanning the laser beam before the semiconductor film irradiated with the first beam spot is completely solidified.    
   
   
       63 . The method of manufacturing a semiconductor device according to  claim 62 , 
 wherein the laser beam is emitted from a continuous wave laser oscillator.    
   
   
       64 . The method of manufacturing a semiconductor device according to  claim 62 , 
 wherein the laser beam is emitted from a pulsed laser oscillator with a repetition rate of 100 MHz or more.    
   
   
       65 . A method of manufacturing a semiconductor device comprising: 
 crystallizing a semiconductor film by irradiating the semiconductor film with a laser beam;    wherein the semiconductor film is scanned with the laser beam along a comb-like line,    wherein when the laser beam is scanned along the comb-like line from a first angle to a fourth angle through second and third angles, a first beam spot centering on the first angle partly overlaps a second beam spot centering on the fourth angle, and    wherein the second beam spot is formed by scanning the laser beam before the semiconductor film irradiated with the first beam spot is completely solidified.    
   
   
       66 . The method of manufacturing a semiconductor device according to  claim 65 , 
 wherein the laser beam is emitted from a continuous wave laser oscillator.    
   
   
       67 . The method of manufacturing a semiconductor device according to  claim 65 , 
 wherein the laser beam is emitted from a pulsed laser oscillator with a repetition rate of 100 MHz or more.