Mass production back-grinding/wafer-thinning technology for GaAs devices

The first mass-production back-grinding technology applicable to a fully-automatic wafer-thinning process in GaAs device manufacturing is described. Excellent productivity has been realized because the brittleness of GaAs has been overcome. A mirror-like stress-free surface was obtained by utilizing the wafer-rotating downfeed grinding method with slight chemical etching. The thickness of the deformed layer due to back-grinding was evaluated at 0.6 mu m. The wafer bow and the changes in electrical characteristics of GaAs devices caused by this layer were eliminated by chemical etching. The threshold voltages of GaAs MESFETs were confirmed to shift negatively by no more than 5 mV. This technology has been successfully demonstrated in several kinds of GaAs device fabrication processes.<
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