Patent ID: 7864294

Claim:
A mask for producing a semiconductor device, the mask comprising: a glass substrate; a layer of transmissive material positioned on the glass substrate, the transmissive material being different from a material of the glass substrate; and an interface between the glass substrate and the layer of transmissive material, the mask having a first trench therein and a second trench therein, the first trench having a selected width and formed to produce a first phase delay, a portion of the glass substrate being located at a bottom of the first trench, the first trench having a depth that is above the interface of the transmissive material and the glass substrate, such that a sidewall of the first trench is formed from a portion of only the layer of transmissive material, the second trench adjacent to the first trench and having the selected width and formed to produce a second phase delay different from the first phase delay, the second trench having a depth below the interface of the transmissive material and the glass substrate, such that a sidewall of the second trench is formed from both a portion of the layer of transmissive material and a portion of the glass substrate.