Patent ID: 7964435

Claim:
A method for diffusing dopant into a semiconductor, wherein: (a) a first desired diffusion depth to which the dopant is to be diffused into the semiconductor at a first location to form a diffusion region for a first device is determined; (b) a diffusion mask is formed over the semiconductor; (c) a first diffusion window is formed in the mask, wherein the first diffusion window aligns with the first location and wherein the first diffusion window has a first size that is greater than the first desired diffusion depth; and (d) dopant is diffused into the semiconductor at the first location to the first desired diffusion depth during a first diffusion operation, wherein all dopant that is to be diffused into the diffusion region of the first device is delivered through the first diffusion window during the first diffusion operation; wherein the improvement comprises: controlling the first diffusion depth based on the size of the first diffusion window, wherein the first size is selected as a function of the first desired diffusion depth, and wherein the larger the first size of the first diffusion window, the shallower the dopant diffusion depth.