The application of channeling to masked ion beam lithography

Abstract

Various orientations of undoped single crystal silicon were examined from the standpoint of transmitted half-angle to determine the best orientation for masked ion beam lithography (MIBL). The effect of boron, present at a level of ∼ 10 20/ cm 3, was also determined. Transmitted angular distributions, for particles of incident energy in the range 80–180 keV, were measured using a moveable silicon surface barrier detector with a resolution of ∼ 3 keV and an acceptance angle of < 0.1°. Planar orientations yielded smaller transmitted half-angles than axial orientations without a significant loss in transmitted yield. The half-angle of particles transmitted along planes, unlike axes, was found to vary with azimuthal angle. The best orientation for use in MIBL was determined to be the {110} planar orientation. Half-angles for particles transmitted along this plane were smallest for scans perpendicular to the plane and largest for scans parallel to it. The presence of boron was found to increase the transmitted half-angle by ∼ 10% over the entire energy range.