Partial Etching of Trench Isolation to Form Self-Aligned Devices
Original Publication Date: 1985-May-01
Included in the Prior Art Database: 2005-Feb-18
This article describes a process and structure for the formation of a self-aligned p+ extrinsic base region. This extrinsic base is self-aligned to the trench and can be used to form a self-aligned guard ring Schottky barrier diode (SBD). The process employs the technique of partial trench etching to define a p+ dopant along the trench sidewall. With proper control of the trench depth and p+ dopant concentration, self-aligned NPN structures, which have a high doped extrinsic base in addition to a butted n+ emitter, can be fabricated. Fig. 1 shows a butted emitter NPN after the isolation pattern has been defined in photoresist which was used to reactive ion etch (RIE) the underlying pyro masking layer 11 and subsequent photoresist strip. Fig. 2 shows the trench etched to a depth of approximately 5000 15%.