A photomask set includes at least two masks that combine to form a device pattern in a semiconductor device. Orthogonal corners may be produced in a semiconductor device pattern to include one edge defined by a first mask and an orthogonal edge defined by a second mask. The mask set may include a first mask with compensation features and a second mask with void areas overlaying the compensation features when the first and second masks are aligned with one another, such that the compensation features are removed when patterns are successfully formed from the first and second masks. The compensation features alleviate proximity effects during the formation of device features.