Systems and methods for producing silicon slim rods
A method and system for preparing polysilicon slim rods, the method and system including: placing a piece of polysilicon on a fixture; applying a predetermined laser beam or abrasive jet to the piece of polysilicon; and separating a polysilicon slim rod from the piece of polysilicon. The laser beam may be used for either cutting or for cracking depending on the operating parameters chosen. There may also be various combinations of cutting and cracking used in order to separate the slim rod from the piece of polysilicon. For example, the laser cut may be a scribing and/or partial cut and the separation may be completed by cracking the remaining silicon. In this case, the cracking may be accomplished by, for example, mechanical bending or laser cracking. Generally speaking, a laser beam used for cracking may be different from and have differing operating parameters from a laser beam used for cutting.
1. A method for preparing polysilicon slim rods, the method comprising:
placing a piece of polysilicon on a fixture;
applying a first predetermined laser beam having a wavelength configured to be moderately absorbed by polysilicon to a first side of the piece of polysilicon, wherein the first predetermined laser beam is formed by at least one laser and configured to produce a non-circular, collimated laser spot extended in a direction of a desired separation;
applying a second predetermined laser beam to a second side, opposite the first side, of the piece of polysilicon, wherein the second predetermined laser beam is formed by at least one laser and configured to produce a non-circular, collimated laser spot extended in the direction of the desired separation;
applying a cooling air let to the first side to cool the first side of the piece of polysilicon;
contacting the second side with a cooled chuck to cool the second side of the piece of polysilicon; and
separating a polysilicon slim rod from the piece of polysilicon, wherein the polysilicon slim rod has a width between approximately 6 mm and 12 mm.
2. The method for preparing polysilicon of claim 1 wherein the first predetermined laser beam is configured to cut the piece of polysilicon.
3. The method for preparing polysilicon of claim 2 wherein the first predetermined laser beam is configured based on a thickness of the piece of silicon along a cut line, a cut depth, and an effect of the second predetermined laser beam.
4. The method for preparing polysilicon of claim 1 wherein the first predetermined laser beam is configured to crack the piece of polysilicon.
5. The method for preparing polysilicon of claim 1 wherein the first predetermined laser beam is configured such that the process feed rate and laser power are controlled by measuring a crack tip position relative to the first predetermined laser beam.
6. The method for preparing polysilicon of claim 1 further comprising:
applying an assist gas during the application of the first predetermined laser beam.
7. The method for preparing polysilicon of claim 1 further comprising:
applying compression to the piece of polysilicon.
8. The method for preparing polysilicon of claim 1 further comprising:
texturizing at least a portion of a surface of the piece of polysilicon prior to applying the first or second predetermined laser beam.
9. The method for preparing polysilicon of claim wherein
the cooling air jet is applied to the piece of polysilicon after or during the application of the first or second predetermined laser beam.
10. The method for preparing polysilicon of claim 1 further comprising:
scribing the piece of polysilicon prior to applying the first or second predetermined laser beam.
11. The method for preparing polysilicon of claim 9 wherein the cooling is applied by cooling jets and the cooling is humidified.