Method for providing high resolution, highly defined, thick film patterns

Abstract

A thick film patterned substrate is provided by laminating together a number of layers of dry photoresist without utilizing a baking step so as to provide an increased thickness resist without shrinkage, coefficient of expansion mismatch or damage to the photographic properties of the final structure. The increased thickness resist is adhered to a substrate, followed by selectively exposing the resist in a single step, developing the resist by directing a pressurized mist to the top surface of the resist and depositing material at the exposed portions of the substrate to the level established by the laminated layers. In the lamination process, the polyethylene release sheet normally used for a layer is peeled off and the layer is laminated to the substrate with the application of heat and pressure. This is followed by peeling off the polyester oxygen barrier sheet from the top of the dry resist. The next resist layer with its release sheet removed is laid on top of the first layer and laminated to the first layer by the application of heat and pressure, with the process being repeated for a number of layers until the desired thickness is achieved. The laminated dry resist and pressurized mist permits patterning of conductive films having a thick film conductivity, with resolution and line uniformity comparable to that obtainable with thin film techniques. For increased pattern definition the top polyester layer is peeled off, with an oil film being substituted to perform as an oxygen barrier and to permit intimate contact of the mask with the top surface of the laminated resist.