Improved Isolation Process for Cmos Technology
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
The need to improve circuit density mandates the use of a field oxidation process capable of yielding a shorter "bird's beak" than existing semi-recessed oxide (SROX) processes. However, any process which relies on an oxidation masking material not capable of withstanding the physical and chemical environment of n-well drive-in processes could not be implemented without giving up the dual self-aligned field tailor implant feature. This article describes a process which not only provides much less bird's beak than current SROX processes but significantly reduces boron depletion in the field regions and boron encroachment in the device regions. Following initial preparation of the substrate 11 and epitaxy 12, a pad oxide film 13 of approximately 50 nm thickness is grown.