Method of making semiconductor device including a first set of windows in a mask with larger ratio of surface area than a second set of windows

摘要

A method of creating two or more semiconductor elements of different characteristics in one and the same semiconductor substrate. Two antimony-diffused regions are formed in a p-type semiconductor region (of a semiconductor substrate for providing embedded layers for two field-effect transistors of unlike characteristics. Then the substrate is overlaid with a mask bearing two different patterns of windows. Then phosphor is introduced into the substrate through the mask windows to create phosphor-diffused regions in overlying relationship to the antimony-diffused regions. The two window patterns of the mask are such that the two phosphor-diffused regions differ in mean phosphor concentration. The embedded layers for the two FETs are obtained as an n-type epitaxial layer is subsequently formed on the p-type semiconductor region in which have been created the antimony-diffused regions and phosphor-diffused regions.