Multilayer photoresist process utilizing an absorbant dye

Claim 1

An improved process of photoetching a substrate, of the portable-conformable-mask type wherein a first resist is deposited on the substrate to produce a bottom resist layer having a substantially planar top surface, a second resist is deposited as a top resist layer producing a multilayer substrate coating having the bottom resist layer sandwiched between the substrate and the top resist layer, the top resist layer is exposed to light in a range in which the second resist is insensitive, said light having been passed through a mask to expose only selected portions of the top resist layer, the top layer is developed to produce a portable-conformable-mask, and the layers of the substrate coating other than the top resist layer are processed to replicate the pattern of this portable-conformable-mask into such layers, the improvement comprising: selecting a dye which strongly absorbs light at the wavelengths used to expose the top resist: dissolving the dye in a layer of resist which is sandwiched between the substrate and the top layer; and replicating the pattern of the portable-conformable-mask into the layer of resist containing the dye by exposing this layer through an associated portable-conformable-mask which has been produced in a layer of resist above the layer of resist containing the dye and then developing the layer of resist containing the dye and then developing the layer of resist containing the dye, said exposure of the layer of resist containing the dye being at a wavelength at which the associated portable-conformable-mask is opaque and at which the layer containing the dye is photosensitive.