Patent ID: 8450212

Claim:
A method, comprising: forming an organic polymer layer on a semiconductor substrate; forming a patterned photoresist layer over said organic polymer layer, said patterned photoresist layer having a first opening and a second opening, said second opening wider than said first opening; performing a first reactive ion etch to transfer the pattern of said first and second openings into said organic polymer layer to form a first trench and a second trench in said organic polymer layer, said second trench wider than said first trench, said first trench extending into but not through said organic polymer layer, said second trench extending through said organic polymer to said semiconductor substrate, said first reactive ion etch forming a first polymer layer on sidewalls of said first trench and a second polymer layer on sidewalls of said second trench, said second polymer layer thicker than said first polymer layer; and performing a second reactive ion etch to extend said first trench through said organic polymer layer to said semiconductor substrate, said second reactive ion etch removing said second polymer layer from sidewalls of said second trench.