solutions. We used a solid hemispherical specimen of singlecrystal
silicon as shown in Fig.1. The radius of the hemisphere
was 22 mm, and its sphericity was less than 10 pm. The surface
was polished to a mirror finish. The surface roughness was 0.005
to 0.007 pm in Ra. All crystallographic orientations appeared on
the hemispherical surface. Measuring the profile before and after
etching and noting the change enabled us to calculate the etching
rate of any orientation. The profile measurement was carried out
using an UPMC550-CARAT (Carl Zeiss Co.) three-dimensional
measuring machine. The surface profile was probed every 2 deg
of latitude ranging from 20 to 90 deg and every 2 deg of longitude
ranging from 0 to 360 deg. The total number of probe points was
6480.