Abstract: 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.

Abstract: 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.

Abstract: High quality epitaxial layers of monocrystalline materials can be grown overlying monocrystalline substrates such as SiC or sapphire by forming a compliant substrate for the growing the monocrystalline layers. Devices and methods for fabricating silicon carbide based heterojunction bipolar devices such as transistors and diodes. These devices are suitable for high power and/or high speed and/or high temperature electronic applications.

Abstract: A new type of electrochemical cell is described which can be used for generating electricity, or in an electrolysis mode can produce gases such as hydrogen and oxygen. The cell is constructed from laterally positioned catalyst layers as electrodes with the gap between the catalyst layers having interposed a solid polymer exchange membrane which provides an ion conductive path from the first catalyst layer to the second. The catalyst layers and the electrolyte are in the form of thin films on the surface of a supporting substrate. A plurality of these cells may be formed on the substrate and interconnected electrically forming a network of series and/or parallel connected cells. Means are provided to feed fuel and oxidant to the electrodes as separate gases through channels.

Abstract: 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.

Abstract: 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.