Bromine/methanol polishing of <100> InP substrates

The dependence of bromine/methanol polishing of <100>InP on a number of major parameters - wafer area, applied pressure, rotational speed, and flow rate - has been studied in detail. For a one volume percent solution, the polishing rate is linearly proportional to flow rate, inversely proportional to wafer area, and independent of pressure and rotational speed. Hence, under our experimental conditions, the polishing action is limited by transport of Br to the wafer surface, and mechanical abrasion of the wafer by the pad is insignificant. The surface topography is controlled by the wafer size and by a parameter ν, defined as the ratio of flow rate/wafer area. For v ν --0.48 ml/(min cm/sup 2/), free etching occurs and pits form on the wafer surface. In addition, as lateral dimensions of the wafer shrink to < --2 cm, surface topography degrades due to edge effects. Under the proper conditions, polishing rates as high as 6 μm/min may be obtained while maintaining excellent surface topography. The polished wafers are free of subsurface damage, as revealed by defect etching