Photoresist and Materials Processing

The sensitization of photoresist materials has been accomplished by several methods. Adequate adhesion of photoresist to a wafer surface is critical for proper process performance. A photoresist can be dispensed by several methods, including spin coating, spray coating, and dip coating. Exposure of a photoresist involves the absorption of radiation and subsequent photochemical change, generally resulting in a modification of dissolution properties. The absorption characteristics of a photoresist largely influence its resolution and process capabilities. The development of exposed photoresist is based on image-wise discrimination. To understand and optimize photoresist development, it is necessary to characterize exposure-dependent dissolution properties. Phenolic photoresists can be developed using buffered alkaline solutions such as sodium metal silicates. Surfactants are used as additives to photoresists, chemical etchants, and developers to improve surface activity or wetting. The application of chemical amplification has been the enabling factor in achieving highly sensitive photoresists for 248 and 193 nm applications.