| 摘要 |
PURPOSE: A heterojunction bipolar transistor(HBT) and a method for forming the same are provided to etch a window through a selected area of indium gallium phosphide layer. CONSTITUTION: A window etching method etches a window through a selected are of indium gallium phosphide layer(InGap)(20). The method forms a silicon nitride layer(32) on a surface of indium gallium phosphide layer(InGap)(20), forms a window through a selected part of a silicon nitride layer(32) exposing a lower part of the selected area of the indium gallium phosphide layer(InGap)(20), and removes an exposed lower part of the indium gallium phosphide layer(InGap)(20). Thereby, a under-cutting of a lateral direction of indium gallium phosphide layer(InGap)(20) is prevented, and a sub-micron window is accurately formed.
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