Omission of thick Si3N4 layers in ISA schemes

The present invention provides a process which comprises: (a) producing an ion-implantation resistant island on a substrate; (b) growing ion-implantation resistant sidewalls on the island; (c) implanting a first impurity; (d) removing the sidewalls; (e) implanting a second impurity where the sidewalls were; (f) growing a conformal etchable coating over the surface of the device; (g) masking to define an area spaced from and exterior to the area where the sidewalls were; (h) removing the conformal etchable coating in the area of step (g); (i) etching a deep trench in the area where the conformal coating was removed; (j) implanting a third impurity into the deep trench. Following island removal, the emitter and base of a bipolar transistor are formed in the area where the island existed.