Photoresist process for reactive ion etching of metal patterns for

Abstract

The process is based upon applying a layer of release agent which is a solution of a polysulfone constituent and a dye, applied to the surface of a polysilicon layer. Thereafter, the photoresist layer can be applied on top of the release agent layer. Then, the photoresist can be optically exposed and developed and its alignment measured. If the alignment of the resultant photoresist structures is found to be incorrect, rework can be easily accomplished by dissolving the release agent in a suitable solvent. This allows the existing photoresist structures to be removed. Then the rework cycle can continue by applying a new layer of the release agent and dye solution and followed by a new photoresist layer. If the original photoresist layer or the reworked photoresist layer is found to have been properly aligned, then the normal processing steps can continue. The process also provides for an improved control over back reflected and diffracted light during the optical exposure step. The presence of a dye which is selected to have an absorption cross-section which peaks at an optical wavelength approximately equal to the emission peak for the wavelength of the exposure light, enables any portion of the exposure light which passes through the photoresist and into the release layer, to be absorbed before it has a chance to be reflected or diffracted back up into the photoresist layer. This enables the photoresist to be uniformly exposed even when it passes over structures which lie beneath the release layer and which might otherwise cause unwanted reflection or diffraction of the exposure light.