Fabrication of a prototype large capacity multiple blade slurry saw is considered. Design of the bladehead which will tension up to 1000 blades, and cut a 45 cm long silicon ingot as large as 12 cm in diameter is given. The large blade tensioning force of 270,000 kg is applied through two bolts acting on a pair of scissor toggles, significantly reducing operator set-up time. Tests with an upside-down cutting technique resulted in 100% wafering yields and the highest wafer accuracy yet experienced with MS slicing. Variations in oil and abrasives resulted only in degraded slicing results. A technique of continuous abrasive slurry separation to remove silicon debris is described

Fleming, J. R.

Holden, S. C.

English

S.C. Holden

J.R. Fleming

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Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the Low Cost Silicon Solar Array Project. Fifth quarterly report, March 21, 1977--May 27, 1977

The multiblade slurry technique capable of slicing 10 cm ingot into wafers 0.25 mm thick with only 0.20 mm kerf loss and 98% yield has been demonstrated. The total silicon requirement represents an ingot to sheet conversion of 0.95 m/sup 2//kg. Full production slicing tests have demonstrated the cost of MS slicing to contribute $40 to $50/m/sup 2/, with ''best effort'' estimates for today's configuration to be $30 to $35/m/sup 2/. By reducing material cost, and increasing the specific capacity of a saw to slice 900 wafers simultaneously, the long-term cost of MS slicing is estimated to be less than $10/m/sup 2/. The conversion of ingot to sheet is shown to be the most valuable contribution of slicing technology. At today's ingot costs, and with the thin wafer, low kerf loss slicing techniques demonstrated, the silicon material represents 5 to 10 times the cost of the wafering process in finished silicon wafers. Increasing the number of blades used in MS slicing from 100 to 150 to 225 to 300 has resulted in a reduction of yield to 33 to 70% for thin slicing, or an increase in wafer thickness to 0.30 mm slices. The limitation is intrinsic misalignment of multiple blades. A technique to correct this condition is presented and forms a key element in low cost slicing. Analysis of blade material accuracy shows that straightness and flatness specifications can be relaxed. The success of the blade alignment technique will allow lower thickness accuracy requirements. The goal is to use blade materials 50% as costly as used presently, reducing the cost of this expendible material

UNT (University of North Texas) Digital Library

NASA Technical Reports Server

Slicing of silicon into sheet material.  Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

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UNT (University of North Texas) Digital Library

NASA Technical Reports Server