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. Fourth quarterly report, December 20, 1976--March 20, 1977

Technical Report · Sun Mar 27 04:00:00 EST 1977

DOI:https://doi.org/10.2172/7309099· OSTI ID:7309099

Holden, S. C.

Two demonstrations of silicon slicing were made for solar cell application. 10 cm ingots of silicon were sliced into 225 wafers (full saw capacity) with over 94 percent yield in both cases. Wafers 0.48 mm thick were sliced with 0.25 mm kerf loss in 19 hours. The slice thickness duplicated currently used wafers. The second demonstration produced 0.30 mm thick slices with 0.25 mm kerf loss in 24 hours. This represents a current best effort with process conditions developed under this contract. Wafer surface damage is shown to be a fine microcrack structure which reduces to a faceted surface topography with 4 ..mu..m of etching. Abrasive particles used in MS sawing do not exhibit particle size degradation or wear of sharp edges. However, built-up silicon debris may effectively blunt cutting edges of the abrasive. Kerf loss was reduced to 0.20 mm in slicing a 10 cm ingot into 0.25 mm slices. This reduces the total silicon requirement per slice by 50 ..mu... Plans include the demonstration of full production capacity with the 0.15 mm thick blades used in this case and a cost analysis of MS sawing for solar cell applications. Limits of wafer thickness (250 ..mu..) and kerf loss (200 ..mu..) are identified for present slicing techniques. These are explained as a result of intrinsic misalignment in the major portion of the blade package used in MS sawing. Accumulation of small component errors is shown to result in 50 to 100 ..mu.. misalignment of blades possibly resulting in fatigue of thin blades (0.10 mm) and breakage of thin slices (less than 250 ..mu..).

• Research Organization: Varian Associates, Lexington, MA (USA). Lexington Vacuum Div.
• DOE Contract Number: NAS-7-100-954374
• OSTI ID: 7309099
• Report Number(s): ERDA/JPL/954374-77/1
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
ABRASIVES
ACCURACY
CRYSTAL STRUCTURE
CUTTING
DIMENSIONS
DIRECT ENERGY CONVERTERS
DISPERSIONS
ELEMENTS
ETCHING
EXPERIMENT PLANNING
FABRICATION
MACHINING
MICROSTRUCTURE
MIXTURES
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PLANNING
PRODUCTION
SEMIMETALS
SILICON
SILICON SOLAR CELLS
SLURRIES
SOLAR CELLS
SURFACE FINISHING
SURFACE PROPERTIES
SUSPENSIONS
THICKNESS