Raytheon Company

Bae Systems Information and Electronic Systems Integration Inc.

Philip A Lamarre

Robert L Mozzi

Multilayer resist systems and techniques used for liftoff or planarizing topography wherein the dimensions and thicknesses of the layers are independently controlled. The undercut may also be independently controlled for precision structures.

Lithographic semiconductor manufacturing using a multi-layered process

A positive photoresist adhesion promoter which is provided as a thin layer between a resist such as polymethylmethacrylate for use on gallium arsenide is described. The positive photoresist adhesion promoter includes a mixture of a positive photoresist with an organic solvent. The use of the positive adhesion promoter increases the resistance of the resist such as PMMA to chemical stress during subsequent processing steps for the circuit. An alternative arrangement is to use a composition of the photoresist to be deposited as the masking layer as adhesion promoter layer and processing the adhesion promoter layer to induce cross linking in the resin component of the photoresist material to thus provide a tenacious bond between the adhesion promoter layer and the material of the substrate, such as gallium arsenide.

Photoresist adhesion promoter

A method of patterning a photoresist layer to provide an aperture having retrograde sidewalls is described. Illumination may be through a conical prism arrangement or a conical reflecting mirror and cylindrical mirror arrangement. The method includes the step of directing energy towards a mask which selectively exposes portions of a photoresist layer disposed on the substrate. The energy is directed to the mask at an oblique angle with respect to the normal to the surface of the substrate. The underlying photoresist layer is obliquely sensitized by the obliquely directed illumination. The portions of the layer which are obliquely sensitized are removed leaving behind an aperture having retrograde sidewalls. The retrograde sidewalls are a preferred photoresist profile for easy and reliable lift-off of deposited material from the semiconductor substrate.

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Waltham, MA, United States of America

Philip A Lamarre