Abstract: A reduced pressure epitaxial deposition method is disclosed to maximize performance and leakage limited yield of devices formed in the epitaxial layer. The method includes specified prebake and deposition conditions designed to minimize arsenic (buried subcollector) and boron (buried isolation) autodoping effects when pressures below one atmosphere are selected in accordance with the subcollector-to-isolation area ratio.

Abstract: A method for fabricating self-aligned regions of semiconductor devices such as bipolar or field effect transistors using three masking layers which are selectively etchable with respect to each other on the surface of the semiconductor body. A dimensional mask is deposited over the three layers so that the set of all of the self-aligned impurity regions to be formed through the surface of the body are defined by etching the upper masking layer, with the intermediate layer acting as an etch-stop. Using conventional wet or dry resist processes, each subset of similar impurity regions may then be formed selectively through the intermediate and lower layers without the need for precisely aligning any subsequent mask.