Latch-Up Free CMOS Structure
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
This article relates generally to integrated circuit construction and, more particularly, to a method of constructing CMOS devices to prevent conduction latch-up. Unwanted conduction latch-up due to minority carriers injected by forward-biased emitter-base junctions can be prevented by forming a recessed n-channel CMOS structure to block the carriers. Referring to Fig. 1, p- substrate 1 is implanted with a high dose of arsenic over its entire surface to form n+ layer 2. An epitaxial n- layer 3 is grown on top of the wafer, and photoresist 4 is exposed and developed to define the p-channel device region. Reactive ion etching with a FREON 12* and oxygen process is used to remove the exposed n- epitaxial layer 3 and underlying n+ layer 2.