Method and apparatus for irradiating a semiconductor material surface by laser energy
A method for irradiating semiconductor material is provided which includes selecting a region of a semiconductor layer surface, irradiating the region with an excimer laser which has a beam spot size, and adjusting the beam spot size to match the selected region size. Further, an apparatus for irradiating semiconductor material is provided. The apparatus includes an excimer laser for irradiating a selected region of a semiconductor layer surface, the laser has a laser beam spot size, and a system for adjusting the laser beam spot size to match the selected region size.
1. A method for irradiating semiconductor material comprising:
selecting a region of a semiconductor material layer surface, the region having a region size and shape;
creating on the semiconductor material layer surface, using an optical system with variable image magnification, an image of a mechanically variable aperture comprising movable blades defining a beam spot size and a shape of an excimer laser beam whose size and shape are mechanically variable;
said image being the closest to the size and shape of the selected region while mechanically variable aperture in its fully open position;
mechanically varying the size and the shape of the mechanically variable aperture by moving the movable blades for adjusting the laser beam spot size and the shape, so that the laser beam spot matches the size and the shape of the selected region; and
irradiating the region of the semiconductor material layer surface with the excimer laser beam having the adjusted beam spot size and the adjusted shape.
2. The method according to claim 1 , further comprising aligning the beam spot in XYZ-direction with the selected region.
3. The method according to claim 1 , further comprising homogenizing the laser beam before matching the beam spot size and the adjusted shape to the selected region size and shape.
4. The method according claim 1 , wherein the selected region is one full die.
5. An apparatus for irradiating semiconductor material comprising:
an excimer laser for irradiating a selected region of a semiconductor material layer surface having a region size and shape, the laser having a laser beam spot size and shape; and
an optical system with variable image magnification for creating, on the semiconductor material layer surface, an image of a mechanically variable aperture comprising movable blades defining the size and the shape of the laser beam spot, said image being the closest to the size and shape of the selected region while the variable aperture is in its fully open position; and
means for mechanically varying the size and the shape of the aperture by moving the movable blades for adjusting the size and the shape of the laser beam spot to the selected region size and shape.
6. The apparatus according to claim 5 , further comprising means for aligning the beam spot in XYZ-direction with the selected region.
7. The apparatus according to claim 5 , further comprising a beam homogenizer positioned before the means for adjusting the laser beam spot size and the laser beam spot shape.
8. Use of an apparatus according to claim 5 for making semiconductor material.
9. The apparatus according to claim 5 , wherein the excimer laser is adapted to produce a laser beam with an energy density between 1 and 10 J/cm 2 .
10. The apparatus according to claim 5 , wherein the beam spot size matches one full die.
11. The apparatus of claim 5 , wherein the means for aligning the laser beam spot in XYZ-direction comprises a camera positioned above the material layer surface for obtaining an image of the material layer surface.
12. The apparatus of claim 11 , further comprising means to process the image to locate plural alignments marks etched on the semiconductor material layer surface.