Manufacturing method of display device
View Patent ↗In crystallization of a silicon film by annealing using a linear-shaped laser beam having a width of the short axis of the beam is ununiform, the profile (intensity distribution) of the laser beam is evaluated and the results are fed back to a condition of oscillating the laser beam or an optical condition for projecting the laser beam onto the silicon film, whereby a display device comprising a high-quality crystalline silicon film is manufactured. The energy distribution of the linear-shaped laser beam is determined by a detector type CCD camera which is moved stepwise in the directions in which its long axis and short axis extend, respectively, and a value obtained by dividing an accumulated intensity E in the long axis direction obtained by accumulating the detected signal in the direction parallel to the short axis by the square root of the width W of the short axis of the above linear-shaped laser beam in each position of the long axis: E/√{square root over ( )}(W), is determined in all the positions of a cross section of the linear-shaped laser beam to evaluate the above intensity distribution.
1. A manufacturing method of a flat display device for obtaining an active matrix substrate for use in a display device by placing a substrate with an amorphous semiconductor film or a granular poly-crystalline semiconductor film formed on the main surface thereof on a stage, and irradiating and annealing a plurality of regions of the amorphous semiconductor film or granular poly-crystalline semiconductor film on the substrate with a laser light shaped into a long and narrow beam while scanning the regions in a direction crossing the long axis direction of the shaped long and narrow laser beam to reform the amorphous semiconductor film or the granular poly-crystalline semiconductor film into a band-like poly-crystalline semiconductor film,
the method comprising:
monitoring a beam profile of the laser light on the substrate,
calculating a maximum power density and a width of the short axis of the beam in the scanning direction from the monitored beam profile, and
scanning and irradiating with the laser light at a constant speed while adjusting laser output based on the calculated maximum power density and the width of the short axis of the beam.
2. A manufacturing method of a flat display device according to claim 1 , wherein
the laser light is continuous-wave laser light or quasi-continuous-wave laser light, and
in adjusting laser output of the radiated laser,
the width of the short axis of the beam in the scanning direction is calculated at regular time intervals from the beam profile on the substrate while scanning with the laser light at a constant speed, and
the laser output is adjusted to a value obtained by multiplying laser output set at the start of irradiation or in advance by the square root of a ratio of the calculated beam width of the short axis to the width of the short axis set at the start of irradiation or in advance.
3. A manufacturing method of a flat display device according to claim 2 , wherein
adjustment of the laser output is performed by a continuously variable transmittance filter comprising a ½ wave plate and a polarizing beam splitter.
4. A manufacturing method of a flat display device according to claim 2 , wherein
adjustment of the laser output is carried out by adjusting a voltage applied to an EO modulator for performing amplitude modulation of the laser light.
5. A manufacturing method of a flat display device according to claim 1 , wherein
the laser light is continuous-wave laser light or quasi-continuous-wave laser light, and
in adjusting laser output of the radiated laser E t , a beam width (the width of the short axis) W t in the scanning direction is calculated at regular time intervals from the beam profile on the insulating substrate while scanning with the laser light at a constant speed,
a laser output E t is adjusted to a value obtained by multiplying a laser output E 0 set at the start of irradiation or in advance by the square root of a ratio of the calculated beam width W t of the short axis to the width W 0 of the short axis set at the start of irradiation or in advance (E t =E 0 ×√(W t /W 0 )).
6. A manufacturing method of a flat display device according to claim 5 , wherein
adjustment of the laser output is performed by a continuously variable transmittance filter comprising a ½ wave plate and a polarizing beam splitter.
7. A manufacturing method of a flat display device according to claim 5 , wherein
adjustment of the laser output is carried out by adjusting a voltage applied to an EO modulator for performing amplitude modulation of the laser light.
8. A manufacturing method of a flat display device according to claim 1 , wherein
the laser light is continuous-wave laser light or quasi-continuous-wave laser light, and
in adjusting laser output of the radiated laser the beam width (the width of the short axis) W(t) of the laser light in the scanning direction on the substrate when scanning the insulating substrate at a constant speed is determined in advance, and
a radiated laser output E(t) is adjusted to a value obtained by multiplying the laser output E 0 set at the start of irradiation or in advance by the square root of a ratio of the width W(t) of the short axis determined in advance to the width W 0 of the short axis set at the start of irradiation or in advance, (E(t)=E 0 ×√(W t /W 0 )).
9. A manufacturing method of a flat display device according to claim 8 , wherein
adjustment of the laser output is performed by a continuously variable transmittance filter comprising a ½ wave plate and a polarizing beam splitter.
10. A manufacturing method of a flat display device according to claim 8 , wherein
adjustment of the laser output is carried out by adjusting a voltage applied to an EO modulator for performing amplitude modulation of the laser light.
11. A manufacturing method of a flat display device according to claim 1 , wherein
scanning and irradiating with the laser light at a constant speed of the substrate is performed while adjusting laser output based on the calculated maximum power density and width of the short axis of the beam so that the temperature rise in a laser irradiated portion becomes constant.