Defect-Free Zero Birds-Beak SWAMI Process
Original Publication Date: 1988-Jun-01
Included in the Prior Art Database: 2005-Feb-15
The conventional SWAMI (sidewall masked isolation) process technique for achieving a "birds-beak"-free planar isolation suffers from a severe dislocation and edge-defect generation problem due to a lack of control of the stress relief oxide undercut. The disclosed enhancement to the SWAMI process involves the addition of a removable polysilicon sidewall to increase the length of the sidewall footing without significant undercut of the sidewall. The process flow of the SWAMI technique is illustrated in Figs. 1-4. In Fig. 1, the stress relief oxide (SRO) 1 is first grown on the silicon substrate 2, followed by deposition of silicon nitride (Si3N4) 3. After photoresist (PR) masking, the pattern illustrated in the figure is obtained by etching away unwanted areas of 1,2 and 3. In Fig.