US PATENT SUBCLASS 438 / FOR 108
.~.~.~ Differential etching (156/633.1)

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438 /   HD   SEMICONDUCTOR DEVICE MANUFACTURING: PROCESS

983  DF  ZENER DIODES {1}
FOR 100  DF  .~ Etching of semiconductor precursor, substrates, and devices used in an electrical function (156/625.1) {17}
FOR 104  DF  .~.~ With uniting of preforms (e.g., laminating, etc.) (156/629.1) {2}
FOR 108.~.~.~ Differential etching (156/633.1) {1}
FOR 109  DF  .~.~.~.~> Metal layer etched (156/634.1)

DEFINITION

Classification: 438/FOR.108

Differential etching:

Foreign art collection for processes wherein an etching material (a) contacts selected surface areas of the substrate to remove a constituent part of the substrate at the selected surface areas only, or (b) treats the substrate at different rates in different areas to produce a nonuniform surface.