Method of producing semiconductor devices

摘要

A recess or pit in a body of silicon is produced by crystallographically damaging a portion of the body and etching that portion to provide a substantially flat bottomed pit. Fig. 1 shows a silicon body 4 subjected to the predetermined pressure of a 3-sided diamond point 6 by means of a weighted lever 8. The body is then etched in a boiling 30% solution of potassium hydroxide for 10 minutes. Fig. 2 shows a silicon wafer 2 suitable for a transistor having an emitter recess 4 and a collector recess 6 produced as above. Sodium hydroxide may be used as the etchant and additives such as ethylene glycol (which tends to flatten the bottom of the recess) or sodium carbonate (to raise the boiling point) may be used. The effect of different concentrations of etchant on recess shape is discussed. The crystallographic damage may be caused by rotation of or scratching by the diamond point.