Local buried oxide technology for HV transistors integrated in CMOS

Abstract

Automotive applications require full dielectric isolation of the high voltage and analog components. Such isolation is typically realized by BCD technologies built on SOI. The drawbacks of using SOI wafers, i.e. deviation from the baseline bulk CMOS and increased overall cost, can be addressed by manufacturing local SOI islands in the standard bulk wafer. This paper presents a method to manufacture a local buried oxide using LoBOX technology and its integration to baseline CMOS. Our LoBOX technology is based on a sacrificial SiGe layer buried in bulk substrate and subsequently replaced with oxide. It is a general isolation solution that allows flexible local SOI and local BOX thickness. We have integrated our LoBOX technology in a 130 nm bulk CMOS process to demonstrate its feasibility. The manufactured HV transistors isolated with local BOX, feature almost identical performance as those manufactured on commercial SOI wafers.

The Versatile Use of SiGe for High-Performance Devices

“…Another application of sacrificial etching of SiGe is the creation of local buried oxide islands, for low power [10] or high voltage applications [11]. The details of the latter process are shown in Figure 6.…”