APPARATUS AND METHOD FOR REPEATEDLY FABRICATING THIN FILM SEMICONDUCTOR SUBSTRATES USING A TEMPLATE
Mechanisms are disclosed by which a semiconductor wafer, silicon in some embodiments, is repeatedly used to serve as a template and carrier for fabricating high efficiency capable thin semiconductor solar cells substrates. Mechanisms that enable such repeated use of these templates at consistent quality and with high yield are disclosed.
1 . A method for making a thin film semiconductor substrate, said method comprising:
providing a reusable semiconductor template;
forming a sacrificial release layer on a front side of said reusable semiconductor template;
epitaxially depositing a thin film semiconductor substrate conformally to said sacrificial release layer;
releasing said thin film semiconductor substrate from said reusable semiconductor template by separation at said sacrificial release layer; and
reconditioning said reusable semiconductor template to remove excess epitaxially deposited thin film semiconductor substrate material to enable production of a second thin film semiconductor substrate.
2 . The method of claim 1 , wherein said semiconductor comprises silicon.
3 . The method of claim 2 , wherein said silicon comprises monocrystalline silicon.
4 . The method of claim 1 , further comprising using a laser to define a boundary of said thin film semiconductor substrate prior to said step of releasing, thereby aiding said step of releasing.
5 . The method of claim 1 , further comprising using bevel grinding of said template containing said epitaxially deposited thin film semiconductor substrate to define a boundary of said thin film semiconductor substrate prior to said step of releasing, thereby aiding said step of releasing.
6 . The method of claim 1 , wherein said step of reconditioning comprises polishing or grinding epitaxially deposited material from a beveled edge of said reusable semiconductor template.
7 . The method of claim 1 , wherein said step of reconditioning comprises lapping or grinding epitaxially deposited material from a surface of said reusable semiconductor template.
8 . The method of claim 1 , wherein said step of reconditioning comprises removing epitaxially deposited material from a back side of said reusable semiconductor template.
9 . The method of claim 1 , wherein said step of reconditioning comprises tape bevel grinding or polishing epitaxially deposited material from a beveled edge of said reusable semiconductor template.
10 . The method of claim 1 , wherein said step of reconditioning comprises removing epitaxially deposited material from said reusable semiconductor template using laser ablation.
11 . The method of claim 10 , wherein said laser ablation uses a water jet guide.
12 . The method of claim 1 , wherein said step of reconditioning comprises removing epitaxially deposited material from said reusable semiconductor template using sonication.
13 . The method of claim 1 , wherein said step of reconditioning comprises removing epitaxially deposited material from said reusable semiconductor template high pressure water or high pressure gas.
14 . The method of claim 1 , wherein said step of reconditioning comprises removing epitaxially deposited material from said reusable semiconductor template using kiss grinding.
15 . The method of claim 1 , wherein said step of reconditioning comprises removing epitaxially deposited material from said a beveled edge of said reusable semiconductor template using programmable precision bevel grinding.
16 . The method of claim 1 , wherein said reusable semiconductor template is tracked within the production process and repeated depositions are carried out in different orientations of said template in order to have symmetric edge and backside depositions.
17 . The method of claim 1 , further comprising measuring the thickness or the weight of said reusable semicondor template prior to a reconditioning area grinding or lapping, in order to determine necessary material removal at said grinding or lapping step or in order to bin it with like templates for subsequent batch lapping or grinding processes.
18 . A method for making a thin film semiconductor substrate, said method comprising:
providing a reusable semiconductor template;
forming a sacrificial release layer on a front side of said reusable semiconductor template;
epitaxially depositing a thin film semiconductor substrate conformally to said sacrificial release layer, said depositing step achieving a reduced back side and edge deposition via at least one of a backside gas purging process or an edge shadow mask; and
releasing said thin film semiconductor substrate from said reusable semiconductor template by separation at said sacrificial release layer.
19 . A method for making a thin film semiconductor substrate, said method comprising:
providing a reusable semiconductor template;
forming a sacrificial release layer on a front side of said reusable semiconductor template;
epitaxially depositing a thin film semiconductor substrate conformally to said sacrificial release layer;
releasing said thin film semiconductor substrate from said reusable semiconductor template by separation at said sacrificial release layer;
performing at least one of a silicon etch, a metal clean, and an organic clean on said reusable semiconductor template to remove residue from previously produced and released thin film semiconductor substrates and on-template processes performed on said thin film semiconductor substrates; and
reconditioning said reusable semiconductor template to enable production of a second thin film semiconductor substrate.