Selective epitaxial growth structure and isolation

A method of fabricating dielectrically isolated integrated circuit devices, comprising the following steps:

• (i) forming a plurality of subcollector regions in a monocrystalline silicon substrate having upper and lower portions, said step (i) including the step of doping said upper portion of said substrate in accordance with types of devices to be formed, said lower portion of said substrate forming said subcollector regions, said step (i) further including the following steps:
• (i)(a) forming a masking layer over said substrate;
• (i)(b) etching a plurality of holes in said masking layer;
• and
• (i)(c) anisotropically etching a plurality of active device regions in said substrate through said holes;
• (ii) growing an oxide layer in said active device regions over portions of said substrate where said devices are to be formed;
• (iii) etching first regions in said oxide layer over said subcollector regions by anisotropically etching a self-aligned hole in said oxide layer in each of said active device regions, said self-aligned hole being directly beneath a corresponding one of said holes in said masking layer;
• and
• (iv) forming said devices by selective epitaxial growth at least in said first regions.