Electrical Defect Test for Silicon and Aluminum Metal Oxide Semiconductor Process
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
The Silicon and Aluminum Metal Oxide Semiconductor (SAMOS) process [IBM J. Res. Develop. 24, 268-282 (May 1980)] employs a polysilicon field shield separated from the silicon substrate by a thin nitrideoxide dual dielectric. This field shield is physically shorted to the silicon substrate with first level metallization. As a result, defects in the dielectric which occur between the field shield and the p-type substrate are inconsequential. Defects in the dielectric which occur in areas where the field shield passes over n-type diffusions, however, short the diffusion to the substrate and render the diffusion inoperative. Defects of this type can be major detractors in defect-limited yield of SAMOS products. Since they are in the silicon-nitride-oxide semiconductor structure, they are known as SNOS defects.