Patent ID: 8658541

Claim:
A method for fabricating shallow trench isolation (STI) structure recesses, comprising: providing a substrate having a patterned mask layer formed thereon corresponding to one or more STI structure recesses to be etched; etching the substrate through the patterned mask layer using a plasma formed from a process gas to form the one or more STI structure recesses on the substrate, wherein the one or more STI structure recesses comprises a plurality of first STI structure recesses grouped into a first region having a first density and a plurality of second STI structures recess grouped into a second region having a second density, wherein the second density is greater than the first density, and wherein the process gas and a source power used to form the plasma are continuously provided while etching the substrate through the patterned mask layer; and pulsing the plasma by pulsing a bias power provided to a substrate support for at least a portion of etching the substrate to control a width of the one or more STI structure recesses, wherein a ratio of an etch depth of the first STI structure recesses in the first region to an etch depth of the second STI structure recesses in the second region is controlled by pulsing the bias power.