Polycrystalline silicon technology for bipolar integrated circuits

Polycrystalline silicon regions in the epitaxial layer of integrated circuits can perform isolation and buried-layer contact, and form surface elements such as field plates, capacitors, crossunders, and electrostatic shields. Recent experimental developments include new methods of selective growth and doping of these polycrystalline regions to provide very high voltage breakdown, low parasitic capacitance, and smooth surfaces with excellent pattern definition.