Patent ID: 8853091
Filing Date: 2014-10-07
Classification: H01L

Abstract:
1. A method for manufacturing a semiconductor die comprising the steps of: providing a semiconductor substrate; processing the substrate to a point where shallow trench isolations (STI) can be formed; depositing underlayers having a predefined thickness on the substrate; depositing a single masking layer having a first thickness on top of the underlayers, wherein the single masking layer is different composition from an underlying nitride layer; etching the single masking layer to have at least one area having a second thickness which is greater than zero and smaller than said first thickness; applying a photolithograthy process to create openings in a top photoresist layer where the shallow trench isolations are to be formed, wherein at least one opening is within an area having the first thickness and at least a second opening is within the at least one area having the second thickness; and etching the substrate to form silicon trenches wherein the depth of a silicon trench depends on the thickness of the single masking layer at the location of the respective opening.