Process of fabricating semiconductor device having isolating oxide rising out of groove

摘要

When an isolating oxide (15c) is formed in a silicon substrate (11), a side wall (14a) is formed on the inner wall of a mask (14a) consisting of a lower silicon oxide layer (12a) and an upper silicon nitride layer (12b) for forming a groove (11a) in the silicon substrate (11) in such a manner as to be laterally spaced from the inner wall of the upper silicon nitride layer (12b), and the isolating oxide (15c) is formed from a silicon oxide layer deposited over the mask (12b) after removal of the side wall (14a) by using a polishing, thereby preventing the isolating oxide (15c) from undesirable side etching during an etching step for the lower silicon oxide layer (12a).