Laser thin film poly-silicon annealing optical system
View Patent ↗A high energy, high repetition rate workpiece surface heating apparatus is disclosed which comprise a XeF laser producing a laser output light pulse beam, an optical system narrowing the laser output light pulse beam in the short axis of the laser output light pulse beam and expanding the laser output light pulse beam to form in a long axis of the beam a workpiece covering extent of the long axis, the optical system focuses the laser output light pulse beam at a field stop with a magnification sufficient to maintain an intensity profile that has sufficiently steep sidewalls to allow the field stop to maintain a sufficiently steep beam profile at the workpiece.
1. A high energy, high repetition rate workpiece surface heating mechanism comprising:
a pulsed gas discharge laser operating producing a laser output light pulse beam;
an optical system narrowing the laser output light pulse beam to less than 20 μm in a short axis of the laser output light pulse beam and expanding the laser output light pulse beam to form in a long axis of the beam a workpiece covering extent of the long axis;
the optical system including a field stop intermediate the laser and the workpiece;
the workpiece comprising a layer to be heated;
wherein the optical system focuses the laser output light pulse beam at a field stop with a magnification sufficient to maintain an intensity profile that has a sufficiently steep sidewall to allow the field stop to maintain a sufficiently steep beam profile at the workpiece without blocking the beam profile at too high an intensity level.
2. The apparatus of claim 1 , further comprising:
a high average power in the laser light output pulse beam as delivered to the workpiece.
3. The apparatus or claim 1 , further comprising:
a linebow correction mechanism in a short axis optical assembly.
4. The apparatus of claim 1 , further comprising:
the linebow correction mechanism comprises a plurality of weak cross cylinders.
5. The apparatus of claim 1 , further comprising:
the optical system comprises a catadioptic projection system.
6. The apparatus of claim 1 , further comprising:
wherein the line width due to laser diffraction and divergence is less than geometric limitations.
7. The apparatus or claim 1 , further comprising:
the system projects adjacent peaks of the nominal XeF spectrum to improve overall depth of focus through the separate center wavelengths of each respective adjacent peak having a different focal plane at the workpiece.
8. The apparatus of claim 1 , further comprising;
a linebow is correction mechanism within a field stop optical assembly correcting linebow at the field stop plane and within a workpiece projection optical assembly correcting linebow at the workpiece plane.
9. An apparatus comprising:
a pulsed gas discharge laser adapted to produce a laser output light pulse beam;
an optical system adapted to narrow the laser output light pulse beam to less than 20 μm in a short axis of the laser output light pulse beam and further adapted to expand the laser output light pulse beam to form in a long axis of the beam a workpiece covering extent of the long axis;
the optical system including a field stop intermediate the laser and the workpiece;
the workpiece comprising a layer to be heated;
wherein the optical system focuses the laser output light pulse beam at the field stop with a magnification sufficient to maintain an intensity profile that has a sufficiently steep sidewall to allow the field stop to maintain a sufficiently steep beam profile at the workpiece, and wherein the optical system is further adapted to trim the profile at the field stop at approximately the 5-10% intensity level.
10. The apparatus of claim 9 , wherein the laser light output pulse beam comprises a high average power as delivered to the workpiece.
11. The apparatus or claim 9 , wherein the apparatus further comprises a linebow correction mechanism disposed within a short axis optical assembly.
12. The apparatus of claim 11 , wherein the linebow correction mechanism comprises a plurality of weak cross cylinders.
13. The apparatus of claim 9 , wherein the optical system further comprises a catadioptic projection system.
14. The apparatus or claim 9 , wherein the apparatus is further adapted to project adjacent peaks of the nominal XeF spectrum to improve overall depth of focus through the separate center wavelengths of each respective adjacent peak having a different focal plane at the workpiece.
15. An apparatus comprising:
a pulsed gas discharge laser adapted to produce a laser output light pulse beam;
an optical system adapted to narrow the laser output light pulse beam to less than 20 μm in a short axis of the laser output light pulse beam and further adapted to expand the laser output light pulse beam to form in a long axis of the beam a workpiece covering extent of the long axis;
the optical system including a field stop intermediate the laser and the workpiece;
the workpiece comprising a layer to be heated;
wherein the optical system focuses the laser output light pulse beam at a field stop with a magnification sufficient to maintain an intensity profile that has a sufficiently steep sidewall to allow the field stop to maintain a sufficiently steep beam profile at the workpiece, but without trimming the intensity profile at or above its full width, half maximum values.
16. The apparatus of claim 15 , wherein the laser light output pulse beam comprises a high average power as delivered to the workpiece.
17. The apparatus or claim 15 , wherein the apparatus further comprises a linebow correction mechanism disposed within a short axis optical assembly.
18. The apparatus of claim 17 , wherein the linebow correction mechanism comprises a plurality of weak cross cylinders.
19. The apparatus of claim 15 , wherein the optical system further comprises a catadioptic projection system.
20. The apparatus or claim 15 , wherein the apparatus is further adapted to project adjacent peaks of the nominal XeF spectrum to improve overall depth of focus through the separate center wavelengths of each respective adjacent peak having a different focal plane at the workpiece.