A semiconductor device provided with a substrate made of material except for semiconductors and having thermal conductivity greater than that of the semiconductor material. The semiconductor device provides, on the support, a metal layer, a primary mesa, and electrodes formed on the primary mesa. The metal layer, which is in contact with the primary mesa, may be made of at least one of tungsten (W), molybdenum (Mo), and tantalum (Ta) with a thickness of the 10 to 60 nm.

A power amplifier module includes a first substrate and a second substrate, at least part of the second substrate being disposed in a region overlapping the first substrate. The second substrate includes a first amplifier circuit and a second amplifier circuit. The first substrate includes a first transformer including a primary winding having a first end and a second end and a secondary winding having a first end and a second end; a second transformer including a primary winding having a first end and a second end and a secondary winding having a first end and a second end; and multiple first conductors disposed in a row between the first transformer and the second transformer, each of the multiple first conductors extending from the wiring layer on a first main surface to the wiring layer on a second main surface of the substrate.

Methods of manufacturing a heterojunction bipolar transistor are described herein. An exemplary method can include providing a base/emitter stack, the base/emitter stack comprising a substrate, an etch stop layer over the substrate, an emitter contact layer over the etch stop layer, an emitter over the emitter contact layer, and/or a base over the emitter. The exemplary method further can include forming a collector. The exemplary method also can include wafer bonding the base to the collector. Other embodiments are also disclosed herein.

A target element to be protected and a protrusion are arranged on a substrate. An insulating film arranged on the substrate covers the target element and at least a side surface of the protrusion. An electrode pad for external connection is arranged on the insulating film. The electrode pad at least partially overlaps the target element and the protrusion as seen in plan view. A maximum distance between the upper surface of the protrusion and the electrode pad in the height direction is shorter than a maximum distance between the upper surface of the target element and the electrode pad in the height direction.

A radio frequency module includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier; and a first circuit component. The power amplifier includes: a first amplifying element; a second amplifying element; and an output transformer that includes a primary coil and a secondary coil. An end of the primary coil is connected to an output terminal of the first amplifying element, another end of the primary coil is connected to an output terminal of the second amplifying element, an end of the secondary coil is connected to an output terminal of the power amplifier, the first amplifying element and the second amplifying element are disposed on the first principal surface, and the first circuit component is disposed on the second principal surface.

A device assembly includes a functional substrate having one or more electronic components formed there. The functional substrate has a cavity extending from a first surface toward a second surface of the functional substrate at a location that lacks the electronic components. The device assembly further includes a semiconductor die placed within the cavity with a pad surface of the semiconductor die being opposite to a bottom of the cavity. The functional substrate may be formed utilizing a first fabrication technology and the semiconductor die may be formed utilizing a second fabrication technology that differs from the first fabrication technology.

A bipolar transistor includes a collector layer, a base layer, and an emitter layer that are formed in this order on a compound semiconductor substrate. The emitter layer is disposed inside an edge of the base layer in plan view. A base electrode is disposed on partial regions of the emitter layer and the base layer so as to extend from an inside of the emitter layer to an outside of the base layer in plan view. An insulating film is disposed between the base electrode and a portion of the base layer, with the portion not overlapping the emitter layer. An alloy layer extends from the base electrode through the emitter layer in a thickness direction and reaches the base layer. The alloy layer contains at least one element constituting the base electrode and elements constituting the emitter layer and the base layer.

A compound semiconductor device comprises a heterojunction bipolar transistor including a plurality of unit transistors, a capacitor electrically connected between a RF input wire and a base wire for each unit transistor of the unit transistors, and a bump electrically connected to emitters of the unit transistors. The unit transistors are arranged in a first direction. The bump is disposed above the emitters of the unit transistors while extending in the first direction. The transistors include first and second unit transistors, the respective emitters of the first and second unit transistors being disposed on first and second sides, respectively, of a second direction, perpendicular to the first direction, with respect to a center line of the bump extending in the first direction. The capacitor is not covered by the bump, and respective lengths of the respective base wires connected respectively to the first and second unit transistors are different.

Flexible transistors and electronic circuits incorporating the transistors are provided. The flexible transistors promote heat dissipation from the active regions of the transistors while preserving their mechanical flexibility and high-frequency performance. The transistor designs utilize thru-substrate vias (TSVs) beneath the active regions of thin-film type transistors on thin flexible substrates. To promote rapid heat dissipation, the TSVs are coated with a material having a high thermal conductivity that transfers heat from the active region of the transistor to a large-area ground.

A bipolar transistor includes a collector layer, a base layer, and an emitter layer that are formed in this order on a compound semiconductor substrate. The emitter layer is disposed inside an edge of the base layer in plan view. A base electrode is disposed on partial regions of the emitter layer and the base layer so as to extend from an inside of the emitter layer to an outside of the base layer in plan view. An insulating film is disposed between the base electrode and a portion of the base layer, with the portion not overlapping the emitter layer. An alloy layer extends from the base electrode through the emitter layer in a thickness direction and reaches the base layer. The alloy layer contains at least one element constituting the base electrode and elements constituting the emitter layer and the base layer.