A power amplifier comprising amplifier circuits of multiple stages. Each of the amplifier circuits of multiple stages includes a bipolar transistor and a base electrode. The bipolar transistor included in each of the amplifier circuits of multiple stages includes a collector layer, a base layer placed on the collector layer, and an emitter mesa placed on part of the region of the base layer. The emitter mesa has a shape elongated in one direction in plan view. The base electrode includes a base main portion arranged in such a manner as to be separated from the emitter mesa with a gap in a direction orthogonal to a lengthwise direction of the emitter mesa in plan view. The base main portion has a shape elongated in a direction parallel to the lengthwise direction of the emitter mesa in plan view and is electrically connected to the base layer.

Solder bumps are placed in direct contact with the silicon substrate of an amplifier integrated circuit having a flip chip configuration. A plurality of amplifier transistor arrays generate waste heat that promotes thermal run away of the amplifier if not directed out of the integrated circuit. The waste heat flows through the thermally conductive silicon substrate and out the solder bump to a heat-sinking plane of an interposer connected to the amplifier integrated circuit via the solder bumps.

Aspects of the disclosure provide an integrated circuit (IC) structure with a bipolar transistor stack within a substrate. The bipolar transistor stack may include: a collector, a base on the collector, and an emitter on a first portion of the base. A horizontal width of the emitter is less than a horizontal width of the base, and an upper surface of the emitter is substantially coplanar with an upper surface of the substrate. An extrinsic base structure is on a second portion of the base of the bipolar transistor stack, and horizontally adjacent the emitter. The extrinsic base structure includes an upper surface above the upper surface of the substrate.

The present disclosure provides a semiconductor structure and a manufacturing method thereof. In the manufacturing method, a first P-type semiconductor layer is provided, and an N-type semiconductor layer and a second P-type semiconductor layer are formed in sequence on the first P-type semiconductor layer. The first P-type semiconductor layer, the N-type semiconductor layer and the second P-type semiconductor layer all include a GaN-based material. When the first P-type semiconductor layer is provided, its upper surface is controlled to be a Ga surface; when the N-type semiconductor layer is formed, its upper surface is controlled to be an N surface; when the second P-type semiconductor layer is formed, its upper surface is controlled to be an N surface. By use of the directivity of wet etching, etching is started from the N surface of the second P-type semiconductor layer and automatically stopped on the Ga surface of the first P-type semiconductor layer 12, thereby avoiding over-etching of the first P-type semiconductor layer and decreased hole carrier concentration. Afterwards, dry etching is performed on the second P-type semiconductor layer and stopped on the upper surface of the N-type semiconductor layer, thus helping to reduce a contact resistance of an electrical connection structure of the N-type semiconductor layer.

A vertical bipolar transistor device is disclosed. The vertical bipolar transistor device includes a heavily-doped semiconductor substrate, a first semiconductor epitaxial layer, at least one first doped well, and an external conductor. The heavily-doped semiconductor substrate and the first doped well have a first conductivity type. The first semiconductor epitaxial layer has a second conductivity type. The first semiconductor epitaxial layer is formed on the heavily-doped semiconductor substrate. The first doped well is formed in the first semiconductor epitaxial layer. The external conductor is arranged outside the heavily-doped semiconductor substrate and the first semiconductor epitaxial layer and electrically connected to the heavily-doped semiconductor substrate and the first semiconductor epitaxial layer.

Solder bumps are placed in direct contact with the silicon substrate of an amplifier integrated circuit having a flip chip configuration. A plurality of amplifier transistor arrays generate waste heat that promotes thermal run away of the amplifier if not directed out of the integrated circuit. The waste heat flows through the thermally conductive silicon substrate and out the solder bump to a heat-sinking plane of an interposer connected to the amplifier integrated circuit via the solder bumps.

Dual-base two-sided bipolar power transistors which use an insulated field plate to separate the emitter/collector diffusions from the nearest base contact diffusion. This provides a surprising improvement in turn-off performance, and in breakdown voltage.

A method of manufacturing a semiconductor device is provided. The method includes: providing a substrate including a first semiconductive region of a first conductive type and gate structures over the first semiconductive region, wherein a gap between the gate structures exposes a portion of the first semiconductive region; and forming a second semiconductive region of a second conductive type in the gap starting from the exposed portion of the first semiconductive region. The forming of the second semiconductive region includes: growing, in a chamber, an epitaxial silicon-rich layer having a first sidewall adjacent to the gate structures and a first central portion; and, in the chamber, shaping the epitaxial silicon-rich layer to form a second sidewall adjacent to the gate structures and a second central portion, wherein a first height difference between the first sidewall and the first central portion is greater than a second height difference between the second sidewall and the second central portion.

A semiconductor device is provided that has a semiconductor substrate, a drift layer of a first conductivity type formed in the semiconductor substrate, a base region of a second conductivity type formed in the semiconductor substrate and above the drift layer, and an accumulation region of the first conductivity type provided between the drift layer and the base region and having an impurity concentration higher than an impurity concentration in the drift layer, wherein the accumulation region has a first accumulation region and a second accumulation region that is formed more shallowly than the first accumulation region is and on a side of a boundary with a region that is different from the accumulation region in a planar view.

A method of forming a lateral bipolar junction transistor (LBJT) that includes providing a germanium containing layer on a crystalline oxide layer, and patterning the germanium containing layer stopping on the crystalline oxide layer to form a base region. The method may further include forming emitter and collector extension regions on opposing sides of the base region using ion implantation, and epitaxially forming an emitter region and collector region on the crystalline oxide layer into contact with the emitter and collector extension regions. The crystalline oxide layer provides a seed layer for the epitaxial formation of the emitter and collector regions.