Abstract: A method of forming a microwave integrated circuit substrate which includes via holes connecting the upper and lower surfaces of the substrate in which the upper end of the via hole is closed by a conductive membrane.

Abstract: The present invention is directed to a microwave integrated circuit formed on a substrate having via holes for either electrical grounding or heat dissipation or both and more particularly to a substrate including via holes which are filled with metal.

Abstract: A method of making a field effect transistor with a modified metal semiconductor Schottky barrier depletion region wherein a GaAs semiconductive active layer on a semiinsulating substrate is supplied with a pair of ohmic contacts and with a gate or barrier electrode between the ohmic contacts and spaced therefrom so that below the surface of the active layer upon which the barrier electrode and ohmic contacts are supplied, an electron-depletion region is formed between each ohmic contact and the gate or barrier electrode. According to the invention, this surface region is treated by bombardment with nitrogen or by the application of a layer thereto to modify the depth of the depletion region so that this depth beneath the treated surface region will differ from that beneath the gate or barrier electrode.

Abstract: A process for obtaining conductive and resistive elements in microwave circuits in which sequentially a layer of a thin film constituted by a high resistive material is deposited on an insulating substrate, a thin film of conductive material is deposited over the high resistence material, the high resistive film is removed by photoetching from areas which are to constitute resistive elements, a masking material is electrolytically grown on the areas constituting the resistive elements, a thick film of conductive material is electrolytically grown over the entire surface, a protecting material is deposited on areas to constitute conductive elements, the thick film of conductive material is removed by ionic erosion from areas unprotected in the previous step and residual protecting material is removed by differential chemical attack.