摘要:
A thin film (at least one atomic layer to about 400 .ANG.) of nickel is electrolytically plated on top of electrolytically-plated gold electrodes in GaAs monolithic microwave integrated circuits (MMICs) without any additional photoresist masking step. The thin electrolytically-plated nickel film improves adhesion of a passivating dielectric layer (e.g., silicon dioxide, silicon nitride, and silicon oxynitride) formed on the electrolytically-plated gold electrodes. The electrolytically-plated nickel film can be removed locally to facilitate the fabrication of plated silver bumps (for off-chip electrical connections and thermal paths) on passivated flip chip MMICs.
摘要:
A multicell transistor for use in a circuit has an input ground plane for an input waveguide and an output ground plane for an output waveguide. The multicell transistor includes a gate electrode coupled to the input waveguide, a drain electrode coupled to the output waveguide, and a source electrode coupled to the input ground plane. An output ground strap spaced from the drain electrode couples the output ground plane to the source electrode. A pair of transmission lines are orthogonally connected to and extend from the gate electrode to form a pair of inductors for matching the impedances of the gate electrode and the input waveguide.
摘要:
A beam lead diode configuration is described, employing a planar proton bombarded conversion region and a low-permittivity dielectric separator. The diode enjoys the mechanical ruggedness of the conventional planar diodes and the electrical performance of conventional mesa-type diodes. The diode structure results in the absence of N-type mesa structures on the substrate, allowing fabrication by relatively low-cost, high-yield photolithographic processes.
摘要:
Mushroom-shaped, solder-capped, small-diameter (approximately 50 to 75 microns or less), metal bumps are used in the flip chip monolithic microwave integrated circuits (MMICs) attachment process to provide devices having improved solder volume uniformity. The operation of the MMIC device is extended to millimeter-wave frequencies. The self-alignment property of the solder reflow flip chip attachment process is retained, and enhanced by the solder cap that extends beyond the periphery of the metal bump. Solder flux instead of solder paste patterns are printed on the assembly substrate to facilitate flip chip attachment. The metal bumps comprise electroplated silver pillars having a first diameter capped with electroplated solder having a second diameter, where the second diameter is larger than the first diameter, and are formed using a multi-layer negative photoresist, multiple exposure processing sequence.
摘要:
A monolithic flip chip microwave integrated circuit module formed using titanium coated copper circuitry and a processing method. A dam is formed on a substrate by forming a thin protective layer such as titanium or other metal on a copper layer formed on a surface of the substrate to which a monolithic microwave integrated circuit is to be attached. The protective layer is oxidized upon exposure to air. Vias or openings are then formed in the oxidized protective layer. Solder is disposed in the openings in the oxidized protective layer, and is confined to the openings while solder is reflowed to attach the integrated circuit to the substrate. The oxidized protective layer serves a dual function that provides both a solder dam and a protective coating for the underlying copper circuitry. Copper surfaces not covered by the oxidized protective layer may be environmentally protected by depositing a thin layer containing electroless plated nickel and electroless plated gold.
摘要:
An integrated circuit assembly that prevents silver migration by providing conductive rims around oxidizable silver contacts that contact a substrate. Typically the silver contacts are supported by respective metal pads on the substrate with a contact potential existing at each contact-pad junction. In many applications an electrical circuit transmits electrical signals via the contacts to produce potential differences between the contacts and create electrical fields at their surfaces. The conductive rims have a work function that is sufficiently small to reduce the electric fields and contact potentials so as to inhibit the ionization of the oxidized contacts' surfaces and prevent silver migration across the metal pads and the substrate.
摘要:
A high power, flip-chip microwave monolithic integrated circuit (MMIC) assembly (30) has a high power microwave monolithic integrated circuit (MMIC) having a surface with an active area (72) in which heat is generated. The assembly also has a host substrate (34). A thermally conductive bump (51) formed over the surface of the MMIC has a first portion (51') in close proximity to and in thermal communication with the active area (72) of the MMIC and a second portion (51") which is in close proximity to and in thermal communication with the host substrate (34). The second portion (51") of the thermal bump (51) has a greater cross-sectional area than the first portion (51'). A multi-layer, multi-exposure method of manufacturing the improved thermal bump (51) includes several steps. A plating membrane (80) is formed on a surface of the MMIC (32). A first layer of negative photoresist is applied to the surface of the plating membrane (80), and is exposed with a first masked pattern of light. A second layer of negative photoresist is applied on top of the first layer of photoresist. The second layer of negative photoresist is exposed with a second masked pattern of light. Unexposed areas of the first and second layers of photoresist form a "T" shape. The first and second layers of photoresist are developed with a photoresist developer, thereby leaving a "T"-shaped via in the photoresist. An electrically and thermally conductive metal is plated onto the plating membrane and into the via to form a substantially "T"-shaped bump (51), which is then attached to a host substrate. The resulting bump has greater cross-sectional area at the host substrate than at the MMIC (32).
摘要:
A high power, flip-chip microwave monolithic integrated circuit (MMIC) assembly (30) has a high power microwave monolithic integrated circuit (MMIC) having a surface with an active area (72) in which heat is generated. The assembly also has a host substrate (34). A thermally conductive bump (51) formed over the surface of the MMIC has a first portion (51') in close proximity to and in thermal communication with the active area (72) of the MMIC and a second portion (51") which is in close proximity to and in thermal communication with the host substrate (34). The second portion (51") of the thermal bump (51) has a greater cross-sectional area than the first portion (51'). A multi-layer, multi-exposure method of manufacturing the improved thermal bump (51) includes several steps. A plating membrane (80) is formed on a surface of the MMIC (32). A first layer of negative photoresist is applied to the surface of the plating membrane (80), and is exposed with a first masked pattern of light. A second layer of negative photoresist is applied on top of the first layer of photoresist. The second layer of negative photoresist is exposed with a second masked pattern of light. Unexposed areas of the first and second layers of photoresist form a "T" shape. The first and second layers of photoresist are developed with a photoresist developer, thereby leaving a "T"-shaped via in the photoresist. An electrically and thermally conductive metal is plated onto the plating membrane and into the via to form a substantially "T"-shaped bump (51), which is then attached to a host substrate. The resulting bump has greater cross-sectional area at the host substrate than at the MMIC (32).
摘要:
A method of fabricating a normally “off” GaN heterostructure field effect transistor having a source and a drain including depositing a passivation layer patterned to cover a channel region between a source and a drain, forming a first opening in the passivation layer, the first opening for defining a gate area in the channel region and the first opening having a first length dimension along a direction of current flow between the source and the drain, and implanting ions in an implant area within the gate area, wherein the implant area has a second length dimension along the direction of current flow shorter than the first length dimension.
摘要:
A process for fabricating a combined micro electromechanical/gallium nitride structure. The micro electromechanical structure comprises a piezoelectric device, such as a piezoelectric switch or a bulk acoustic wave device. According to the process, high Q compact bulk acoustic wave resonators can be built. The process is applicable to technologies such as tunable planar filter technology, amplifier technology and high speed analog-to-digital converters.