Lawrence D. Dyer

Dislocation-free Czochralski growth of 〈110〉 silicon crystals

Abstract Previous difficulties in growing dislocation-free 〈110〉 silicon crystals were examined experimentally and a pragmatic solution was proposed, that of introducing one or more bulges into the stem between the seed and the crystal. The new stem growth procedure yielded ten dislocation-free out of ten crystals in the laboratory. Dislocations parallel to the growth axis were shown to grow away from the axis under the influence of an increasing stem diameter, and also to multiply in some cases. The rate of losing dislocations by changing the stem diameter exceeded the rate of gaining dislocations by multiplication, however. The favourable results obtained with the 〈110〉 stem growth procedure are consistent with previous authors concepts of the immobilization of dislocations at low stem diameters and their release at larger diameters. Possible causes of the diversion of the axial dislocations are discussed.

Prevention of Hertzian cracks in the handling of semiconductor ingots

Abstract Brittle contact damage can be conveniently divided into two types: blunt indenter (Hertzian) cracking and sharp indenter cracking. Hertzian fracture is familiar to most people in the form of the small cone crack that appears when a pebble hits a glass window. The purpose of the present paper is to describe the occurrence and prevention of such cracking in silicon crystals. A review is given of Hertzian fracture, its study on silicon, and features that allow one to recognize its occurrence. The important influences of impact loading, tangential force, and surface damage are described. Two places in silicon slice manufacturing where Hertzian damage to crystal ingots may be a substantial problem are described. These problems will likely also occur in the manufacture of gallium arsenide and mercury cadmium telluride.