TW261694B - Stress free field oxide process of integrated circuit - Google Patents

Abstract

A stress free field oxide process of integrated circuit includes the following steps: (1) supplying one substrate; (2) forming one pad oxide on the substrate surface; (3) etching the specified area of pad oxide till the substrate bottom for forming opening to expose the substrate area on which field oxide will be formed; (4) with the pad oxide as mask etching the substrate to form one deep trench in the opening; (5) depositing one Si3N4 layer on the pad oxide surface and in the trench; (6) depositing one Al-Si alloy layer covering on the Si3N4 layer; (7) etching off the Al-Si alloy layer, thereby forming multiple silicon nodules on the Si3N4 layer surface; (8) oxidizing the silicon nodules to form multiple SiO2 nodules; (9) with the SiO2 nodules as mask etching the Si3N4 layer and the substrate part uncovered by the pad oxide, used for forming multiple Si pillars in the opening of the substrate; (10) through those Si pillar gaps implanting selectively ion into the substrate to form channel stop layer; (11) oxidizing those Si pillars into SiO2 in which the increased volume by oxidization compensates those Si pillar gaps and the trench depth, constituting one flat field oxide area; (12) removing those SiO2 nodules, the Si3N4 layer and the pad oxide layer to complete stress free field oxide area of the integrated circuit.