Abstract: A process for forming grooves of different depths using a single masking step is presented. In the preferred embodiment of the present invention a photoresist material is used as a single masking layer. The grooves of different types are defined in the masking layer such that the image for a first type groove is narrower in width than the image for a second type groove. The grooves are then formed by subsequent etching steps using conventional etching and anisotropic etching techniques. The grooves are etched to different depths by calculating the proper thickness of a protective layer in relationship to the different groove widths which will allow the deeper groove to be etched without affecting the shallower groove.

Abstract: A process for fabricating doped regions in a semiconductor substrate 10 beneath regions of oxidized silicon 21 includes the steps of fabricating a first mask 23 over the substrate 10 except where field regions 21 are desired, introducing p type impurity 30 in to the unmasked regions, oxidizing the silicon substrate 10 except where overlayed by the first mask 23 to form field regions 21, fabricating a second mask 28/23 over the semiconductor substrate 10 except for second field regions, introducing n conductivity type impurity 32 into the second field regions, and oxidizing the substrate to form second field regions 21.