Laser annealing method
View Patent ↗In crystallizing an amorphous silicon film by illuminating it with linear pulse laser beams having a normal-distribution type beam profile or a similar beam profile, the linear pulse laser beams are applied in an overlapped manner. There can be obtained effects similar to those as obtained by a method in which the laser illumination power is gradually increased and then decreased in a step-like manner in plural scans.
1. A method of manufacturing a thin film transistor comprising:
forming a semiconductor film including amorphous silicon having a thickness of 150 to 1000 Å over a substrate;
emitting a pulse laser light at a rate of N pulses per second;
shaping the pulse laser light into a beam having a cross section perpendicular to a propagation direction of the beam, said cross section having a width and a length, wherein the length is longer than the width, wherein the beam has a normal-distribution type energy profile of width L (m) perpendicular to the length direction, where L is larger than zero, and the beam having substantially a constant energy distribution along a lengthwise direction;
applying the beam to a portion of the semiconductor film; and
scanning the semiconductor film with the beam perpendicular to the lengthwise direction of the cross section at a speed V (m/s) in order to crystallize said semiconductor film,
wherein the number of beams applied to said portion in one scan satisfies a relationship 3≦LN/V≦100, and
wherein the width L (m) is defined as a beam in a region having 5% or more of an energy density with respect to a maximum energy density of the beam on the irradiation surface.
2. The method of claim 1 , wherein the width is 0.1 to 1 cm.
3. The method of claim 1 , wherein the length is 10 to 30 cm.
4. The method of claim 1 , wherein the scanning step is conducted in air.
5. The method of claim 1 , an average single-pulse energy density of the beam is set at 100 to 500 mJ/cm 2 .
6. The method of claim 1 , wherein the pulse laser comprises an excimer laser.
7. The method of claim 1 , wherein the number of beams applied to said portion in one scan satisfies a relationship 10≦LN/V≦30.
8. A method of manufacturing a thin film transistor comprising:
forming a semiconductor film including amorphous silicon having a thickness of 150 to 1000 Å over a substrate;
crystallizing the semiconductor film by performing a heat treatment to the semiconductor film;
emitting a pulse laser light at a rate of N pulses per second;
shaping the pulse laser light into a beam having a cross section perpendicular to a propagation direction of the beam, said cross section having a width and a length, wherein the length is longer than the width, wherein the beam has a normal-distribution type energy profile of width L (m) perpendicular to the length direction, where L is larger than zero, and the beam having substantially a constant energy distribution along a lengthwise direction;
applying the beam to a portion of the crystallized semiconductor film; and
enhancing a crystallinity of the crystallized semiconductor film by scanning with the beam perpendicular to the length direction of the cross section at a speed V (m/s),
wherein the number of beams applied to said portion in one scan satisfies a relationship 3≦LN/V≦100, and
wherein the width L (m) is defined as a beam in a region having 5% or more of an energy density with respect to a maximum energy density of the beam on the irradiation surface.
9. The method of claim 8 , wherein the width is 0.1 to 1 cm.
10. The method of claim 8 , wherein the length is 10 to 30 cm.
11. The method of claim 8 , wherein the scanning step is conducted in air.
12. The method of claim 8 , an average single-pulse energy density of the beam is set at 100 to 500 mJ/cm 2 .
13. The method of claim 8 , wherein the pulse laser comprises an excimer laser.
14. The method of claim 8 , wherein the number of beams applied to said portion in one scan satisfies a relationship 10≦LN/V≦30.
15. A method of manufacturing a thin film transistor comprising:
forming a semiconductor film including amorphous silicon having a thickness of 150 to 1000 Å over a substrate;
emitting a pulse laser light at a rate of N pulses per second;
shaping the pulse laser light into a beam having a cross section perpendicular to a propagation direction of the beam, said cross section having a width and a length, wherein the length is longer than the width, wherein the beam has a trapezoidal energy profile of width L (m) perpendicular to the length direction, where L is larger than zero, and the beam having substantially a constant energy distribution along a lengthwise direction;
applying the beam to a portion of the semiconductor film; and
scanning the semiconductor film with the beam perpendicular to the lengthwise direction of the cross section at a speed V (m/s) in order to crystallize said semiconductor film,
wherein the number of beams applied to said portion in one scan satisfies a relationship 3≦LN/V≦100, and
wherein the width L (m) is defined as a beam in a region having 5% or more of an energy density with respect to a maximum energy density of the beam on the irradiation surface.
16. The method of claim 15 , wherein the width is 0.1 to 1 cm.
17. The method of claim 15 , wherein the length is 10 to 30 cm.
18. The method of claim 15 , wherein the scanning step is conducted in air.
19. The method of claim 15 , an average single-pulse energy density of the beam is set at 100 to 500 mJ/cm 2 .
20. The method of claim 15 , wherein the pulse laser comprises an excimer laser.
21. The method of claim 15 , wherein the number of beams applied to said portion in one scan satisfies a relationship 10≦LN/V≦30.
22. The method of claim 15 , wherein the beam has substantially a constant energy distribution along the direction.
23. A method of manufacturing a thin film transistor comprising:
forming a semiconductor film including amorphous silicon having a thickness of 150 to 1000 Å over a substrate;
crystallizing the semiconductor film by performing a heat treatment to the semiconductor film;
emitting a pulse laser light at a rate of N pulses per second;
shaping the pulse laser light into a beam having a cross section perpendicular to a propagation direction of the beam, said cross section having a width and a length, wherein the length is longer than the width, wherein the beam has a trapezoidal energy profile of width L (m) perpendicular to the length direction, where L is larger than zero, and the beam having substantially a constant energy distribution along a lengthwise direction;
applying the beam to a portion of the crystallized semiconductor film; and
enhancing a crystallinity of the crystallized semiconductor film by scanning with the beam perpendicular to the lengthwise direction of the cross section at a speed V (m/s),
wherein the number of beams applied to said portion in one scan satisfies a relationship 3≦LN/V≦100, and
wherein the width L (m) is defined as a beam in a region having 5% or more of an energy density with respect to a maximum energy density of the beam on the irradiation surface.
24. The method of claim 23 , wherein the width is 0.1 to 1 cm.
25. The method of claim 23 , wherein the length is 10 to 30 cm.
26. The method of claim 23 , wherein the scanning step is conducted in air.
27. The method of claim 23 , an average single-pulse energy density of the beam is set at 100 to 500 mJ/cm 2 .
28. The method of claim 23 , wherein the pulse laser comprises an excimer laser.
29. The method of claim 23 , wherein the number of beams applied to said portion in one scan satisfies a relationship 10≦LN/V≦30.
30. The method of claim 23 , wherein the beam has substantially a constant energy distribution along the direction.