Dislocation-Free Silicon on Sapphire by Wafer Bonding

概要

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A 300 μm thick silicon wafer with oxide of 200 A in thickness which prevents void formation is sticked with a sapphire wafer at room temperature. To avoid the crack generation of a silicon wafer, a sticked wafer is heated up to 270C for 2 h and then a silicon layer is removed by grinding from 525 μm to 10 μm. To remove grinding damage and to further thin the silicon layer to 3 μm, KOH etching at 80C is used. Finally, to obtain the silicon layer having the thickness range of 0〜3 μm, polishing is employed. Although the high density of dislocations is observed in the 2.2 μm thick specimen annealed at 900C for 2 h, however, when the specimen is thinned down to 0.2 μm, silicon layer becomes dislocation-free, as confirmed by double crystal X-ray topography and transmission electron micro-scope (TEM). The thin oxide between silicon and sapphire plays an important role in the prevention of diffusion of boron as a contaminant at the bonded interface.
社団法人応用物理学会の論文
1994-01-30