Low cost high quality shallow isolation trench production in a silicon substrate

摘要

Shallow isolation trenches are formed in a silicon substrate by selectively implanting oxygen, thermally growing silicon dioxide and chemical-mechanical polishing (CMP). A shallow isolation trench oxide is formed in a silicon substrate (10) by: (a) forming a structured STI (shallow trench isolation) mask (12) layer directly on the substrate surface; (b) implanting oxygen into the exposed surface portions (14) to define implanted regions; (c) removing the STI mask; (d) thermally growing silicon dioxide on the surface to form silicon dioxide regions which replace the implanted regions; and (e) removing the oxide from the surface by CMP. An Independent claim is also included for a similar process which comprises: (a') forming a structured photoresist mask layer directly on the substrate surface; (b') implanting O2 into the exposed surface portions to define implanted regions; (c') removing the photoresist mask; (d') heating the substrate to 900-1000 deg C to grow silicon dioxide on the surface and to react the implanted O2 so that the implanted O2 regions are replaced by silicon dioxide; and (e') planarizing the structure. Preferred Features: Chemical-mechanical polishing is used for the planarizing step (e'). Oxygen implantation is carried out such that the peak concentration of implanted oxygen lies at about 2500 Angstrom below the substrate surface.