Paul S. Gleim

Thermal Stress and Plastic Deformation of Thin Silicon Slices

Thermal stress and subsequent plastic deformation can be caused in a thin slice of silicon by temperature gradients which arise during the transient periods of heat cycling. They arise either because of the radiation shielding effect of neighboring slices in a parallel row of slices, or the heat sink effect of the boat on which the slices stand, or because of the effect of both. Spacing between the parallel slices, type of boat used, heating and cooling rates, and furnace temperature affect the temperature gradients and the amount of plastic deformation. Study of slip patterns showed that the tangential component of thermal stress was responsible for slip, and that multiple slip was more common than single slip under the conditions investigated.

The influence of crystal orientation on silicon semiconductor processing

Silicon crystallographic orientation effects on semiconductor processing from single crystal growth through completed devices or circuits have been studied. The preferred octahedral crystal habit of silicon provides for stable crystal growth on the {111} plane, but the other low-index planes, {110} and {100}, are becoming more commonly used, in spite of greater difficulty in growth and processing of these crystals. Chemical and physical properties such as etch rates and Youngs modulus are affected by orientation. The effect of crystal orientation on technologies such as diffusion under film (DUF), dielectric isolation, epitaxy, selective etch and epitaxial refill, and simultaneous deposition of single crystal and polycrystal silicon are presented. In addition, orientation effects on processes of oxidation, diffusion, alloying, and scribing are discussed.