Mechanical reliability effects of back-grinding upon GaAs LSI chips

The brittle damage layer of background GaAs LSI chips has been investigated through fracture toughness experiments, etching rate measurements, and SEM (scanning electron microscope) observations. The rough grinding damage which has a negative influence on the mechanical reliability of GaAs LSI chips penetrates to a 5-μm depth on the finished surface. This is a little larger than than expected because the ductile damage layer due to rough grinding is only 0.6 μm thick. However, this damage can be completely removed by 5-μm mirror grinding and 1-μm chemical etching, because the mirror grinding damage generates a 0.6-μm-thick ductile deformation layer and a negligibly thin brittle deformation layer, which do not influence mechanical reliability