High stability planar Zener diode - has split low doped N zones with higher doped N bridge zone under oxide layer

摘要

The planar zener diode design is for +-5 mV stability of breakdown voltage and is not affected by impurity level in the oxide layer. The n type zone (3) is diffused into the p type slice (2) in the form of three zones, two low doped n+ type (3a) with a smaller, shallower n++ type higher doped zone interconnecting them. The zener breakdown occurs along the base (7) of the higher doped n++ zone (3b) instead of at the oxide layer (4) with its etched central metallisation (5). A further metallisation (6) provides the connection to the p-type zone. The device is suitable for voltage regulation applications in vehicles.