Lateral MOSFET with buried drain extension layer

摘要

An integrated circuit containing an extended drain MOS transistor which has a drift layer, an upper RESURF layer over and contacting an upper surface of the drift layer, and a buried drain extension below the drift layer which is electrically connected to the drift layer at the drain end and separated from the drift layer at the channel end. A lower RESURF layer may be formed between the drift layer and the buried drain extension at the channel end. Any of the upper RESURF layer, the drift layer, the lower RESURF layer and the buried drain extension may have a graded doping density from the drain end to the channel end. A process of forming an integrated circuit containing an extended drain MOS transistor which has the drift layer, the upper RESURF layer, and the buried drain extension.

主权项

1. An integrated circuit, comprising:
a semiconductor substrate having a first conductivity type; an epitaxial layer disposed on a top surface of the semiconductor substrate, the epitaxial layer having the first conductivity type; and an extended drain metal oxide semiconductor (MOS) transistor including:
a drift layer formed in the epitaxial layer, the drift layer having a second conductivity type opposite of the first conductivity type, and the drift layer contacting a drain diffused contact region and proximate to a channel region of the extended drain MO S transistor;an upper RESURF layer formed in the epitaxial layer over the drift layer to contact a top surface of the drift layer spaced apart from a source diffused contact region, the upper RESURF layer having the first conductivity type; anda buried drain extension formed in the substrate, the buried drain extension abutting the drift layer below the drain diffused contact region and separated from the drift layer below the channel region, the buried drain extension having the second conductivity type.