Novel diffusion effects in a dielectrically isolated BIMOS process using SOI substrates

The implementaton is discussed of a bulk BIMOS process which incorporates vertical bipolar devices on a thick (5 mu m) film silicon-on-insulator (SOI) substrate. When trench isolation is incorporated in such a process, fully dielectrically isolated devices can be fabricated. By appropriate application of the trench technology, no change in the electrical device parameters will be produced by such processing. It has been demonstrated that epitaxially thickened ZMR (zone-melting recrystallization) and SIMOX (separation by implantation of oxygen) substrates can support a wide range of devices such as those found in the BIMOS process. However, for device structures in which electrical parameters are sensitive to the diffusion of dopants in silicon it may be necessary to adjust the process to allow for small changes in diffusivity in SOI material. This has been demonstrated in the case of oxidation enhanced diffusion.< >