The Preparation of Semiconductor Devices by Lapping and Diffusion Techniques

A new approach to the fabrication of semiconductor devices has been investigated. This approach allows the processing of large semiconductor wafers to a point where they can be diced into numerous and identical devices. Lapping, instead of etching, is employed for all shaping of the units, and the high degree of precision built into the lapping apparatus is passed on to all of the devices prepared. The approach is applicable to the fabrication of a great variety of semiconductor devices. Unipolar, photo-unipolar, as well as bipolar transistors and negative resistance devices, have been fabricated. These devices exhibit superior electrical characteristics. Silicon power transistors have current transfer ratios in the 20 to 40 range and power gains from 30 to 40 db. Silicon unipolar transistors have transconductances in the neighborhood of 500 ¿mhos and input resistance of about 100 megohms. Silicon photo-unipolar transistors show a dc photo response of 2 to 20 a per 1m.