Abstract: A method of making a semiconductor device with self-aligned ohmic contacts which exhibits substantially reduced shadowing. The gate material is covered with a layer of gate mask material. The gate mask material is selectively removed to form a gate mask having sidewalls with slope profiles of an inclination sufficient to avoid maximum shadow encroachment for subsequent material depositions. Gate mask material is characterized by the sidewalls having an angularity relative to the surface of the substrate which is at least as great as the angle of evaporative deposition of ohmic contact material from a point evaporative source to the extreme gate position on the substrate.

Abstract: A (GaAs-resident) application specific monolithic microwave integrated circuit (ASMMIC) is fabricated through the use of footprints that include a portion of the metallization through which the circuit components within the wafer are to be interconnected. The metallization is a three layers structure, the first two layers of which include strategically arranged reactance circuit components (MIM) capacitors. A first of the three metal layers is formed on a first surface of the substrate which contains a plurality of semiconductor device regions and conductive material for ohmic contact to the regions, so that portions of the first metal layer are in ohmic contact with the conductive material. The first metal layer provides the bottom plate of the MIM capacitors. A dielectric layer, which serves as the dielectric insulator of the MIM capacitors, is formed on second portions of the first metal layer.

Abstract: A method and resulting circuit structure (10) are disclosed for sputtering metallic silicide gates (18) on gallium arsenide integrated circuit structures. Silicon and metallic layers (14,15,14') are sputtered onto a gallium arsenide substrate (12) for stable high-temperature gate metallizations on VLSI structures.

Abstract: A self-aligned MESFET is formed by implanting a first (channel) region in a first surface portion of a gallium arsenide substrate. A dielectric layer is formed on the surface of the substrate and portions of this layer are selectively removed, to leave a relatively thick substitutional gate mesa overlying a first surface portion of the first region and a relatively thin protective portion, contiguous with the substitutional gate, overlying a second surface portion of the first region, so that the substitutional gate has sidewalls extending above the protective portion. Sidewall spacers are formed contiguous with the sidewalls of the substitutional gate, so as to overlie surface portions of the protective portion of the dielectric layer contiguous with the substitutional gate. Ions are implanted into the substrate using the substitutional gate and the sidewall spacers as a mask, thereby forming source and drain regions in the first region.

Abstract: A GaAs logic circuit including a current control FET that provides high current for switching an output FET, but limits the forward biasing of the output FET at the end of a transition to input logic 1 by controlling the steady state value of current to a gate of the output FET, which limits the voltage applied to the gate of the output FET to a given value. A bias circuit referenced to the voltage applied to the source of the output FET applies a nominal gate voltage to the current control FET. The value of the nominal gate voltage is such as is required to limit the value of the steady state current to the gate of the output FET to that which limits the voltage applied to such gate to the desired given value. Such nominal gate voltage is obtained by shifting the source voltage by the amount of the nominal threshold voltage V.sub.Te of an enhancement-mode FET of the bias circuit. If the nominal threshold voltage V.sub.

Abstract: A process for producing a semiconductor device includes depositing a layer of insulator material onto a supporting substrate of the type having a surface which includes a channel region below the surface thereof containing a carrier concentration of a desired conductivity type, removing selected portions of the insulator material to form a substitutional gate on the substrate surface, forming side walls bounding substitutional gate to define an effective masking area in cooperation with the substitutional gate, ion implanting a dopant into the unmasked region of the substrate, removing the side walls, annealing the resultant device, removing the substitutional gate, depositing gate metal and first and second ohmic contacts in correct positional relation to one another on the substrate, and depositing metallic interconnects in electrical communication with the ohmic contacts to produce a semiconductor device.

Abstract: A GaAs logic circuit uses a first FET to control the application of a logic signal from an input to an output. The first FET inherently has parasitic gate-to-source and gate-to-drain diodes. A control signal applied to the gate of the first FET controls the application of the logic signal to the output through the first FET. For a first FET that is an enhancement mode GaAs device, the gate current tends to forward bias such diodes under all operating conditions and tends to significantly increase the gate current. For a first FET that is a depletion-mode device, adverse operating temperatures can cause such tendency to forward bias these diodes and other circuit diodes. A limiter FET connected to the gate to limit the gate current and thus limits the forward biasing of the parasitic and circuit diodes. This reduces the effect on the gate current of variations in the power supplies to the FET, process variations and operating temperature variations.