Method of self-aligning a trench isolation structure to an implanted well region.

摘要

A method for self-aligning an isolation structure to a diffusion region. A first masking layer is formed on a semiconductor substrate, the first masking layer having at least one aperture sidewall which is substantially perpendicular to the semiconductor substrate. Dopant ions are implanted into the semiconductor substrate through the first masking layer to form a doped region. Sidewall spacers are then defined on the sidewalls of the aperture, and a sidewall image reversal process is carried out such that the sidewall spacers define trench apertures in a masking structure. Finally, isolation trenches are etched into the semiconductor substrate through the masking structure. Alternatively, the implantation step is carried out after the sidewall spacers are defined on the first masking layer. Alternatively, first sidewall spacers are defined, followed by the implantation step and the formation of second sidewall spacers.