The present invention addresses a problem associated with exposing a photoresist layer of non-uniform thickness. Oftentimes, trench patterns etched into a layer of a semiconductor structure will have trenches of varying sizes. Larger trenches in the structure become filled with photoresist material, while smaller trenches do not leading to non-uniformity of photoresist layer thickness with respect to the large and small trenches. The present invention addresses this non-uniformity in photoresist layer thickness by employing at least two exposure steps when exposing the photoresist layer. A first exposure step exposes portions of the photoresist layer corresponding to the large trenches using a first reticle and first energy level. Next, a second exposure step exposes portions of the photoresist layer corresponding to the small trenches using a second reticle and second energy level. The first and second energy levels corresponding to proper exposure of the respective photoresist layer portions of different thicknesses.