A semiconductor structure including a substrate, a BJT, a first interconnect structure and a second interconnect structure is provided. The substrate has a first side and a second side opposite to each other. The BJT is located at the first side. The BJT includes a collector, a base and an emitter. The collector is disposed in the substrate. The base is disposed on the substrate. The emitter is disposed on the base. The first interconnect structure is located at the first side and electrically connected to the base. The second interconnect structure is located at the second side and electrically connected to the collector. The first interconnect structure further extends to the second side. The first interconnect structure and the second interconnect structure are respectively electrically connected to an external circuit at the second side. The semiconductor structure can have better overall performance.

A bipolar junction transistor (BJT) containing sensor that includes a vertically oriented stack of an emitter overlying a supporting substrate, a base region present directly atop the emitter and a collector atop the base region. A first extrinsic base region is in contact with a first sidewall of a vertically oriented base region. The first extrinsic base region is electrically contacted to provide the bias current of the bipolar junction transistor during sensor operation. A second extrinsic base region is in contact with a second sidewall of the base region. The second extrinsic base region includes a sensing element. A sample trench is present adjacent to the BJT having a trench sidewall provided by the sensing element.

A method includes forming a deep well region of a first conductivity type in a substrate, implanting a portion of the deep well region to form a first gate, and implanting the deep well region to form a well region. The well region and the first gate are of a second conductivity type opposite the first conductivity type. An implantation is performed to form a channel region of the first conductivity type over the first gate. A portion of the deep well region overlying the channel region is implanted to form a second gate of the second conductivity type. A source/drain implantation is performed to form a source region and a drain region of the first conductivity type on opposite sides of the second gate. The source and drain regions are connected to the channel region, and overlap the channel region and the first gate.

A bipolar junction transistor (BJT) containing sensor that includes a vertically oriented stack of an emitter overlying a supporting substrate, a base region present directly atop the emitter and a collector atop the base region. A first extrinsic base region is in contact with a first sidewall of a vertically oriented base region. The first extrinsic base region is electrically contacted to provide the bias current of the bipolar junction transistor during sensor operation. A second extrinsic base region is in contact with a second sidewall of the base region. The second extrinsic base region includes a sensing element. A sample trench is present adjacent to the BJT having a trench sidewall provided by the sensing element.

A vertical, single column compound semiconductor bipolar junction transistor device includes an all-around extrinsic base. Homojunction and heterojunction devices are formed using III-V compound semiconductor materials with appropriate bandgaps. Fabrication of the transistor device includes epitaxially growing a III-V compound semiconductor base region on a heavily doped III-V compound semiconductor bottom layer. A polycrystalline emitter/collector layer and the all-around extrinsic base are grown on the base region.

A vertical, single column compound semiconductor bipolar junction transistor device includes an all-around extrinsic base. Aspect ratio trapping is employed during fabrication of the transistor device on a silicon substrate. Homojunction and heterojunction devices are formed using III-V materials with appropriate bandgaps. The emitter of the device may be electrically connected by a lateral buried metal contact.

A vertical, single column compound semiconductor bipolar junction transistor device includes an all-around extrinsic base. Homojunction and heterojunction devices are formed using III-V compound semiconductor materials with appropriate bandgaps. Fabrication of the transistor device includes epitaxially growing a III-V compound semiconductor base region on a heavily doped III-V compound semiconductor bottom layer. A polycrystalline emitter/collector layer and the all-around extrinsic base are grown on the base region.

A vertical, single column compound semiconductor bipolar junction transistor device includes an all-around extrinsic base. Homojunction and heterojunction devices are formed using III-V compound semiconductor materials with appropriate bandgaps. Fabrication of the transistor device includes epitaxially growing a III-V compound semiconductor base region on a heavily doped III-V compound semiconductor bottom layer. A polycrystalline emitter/collector layer and the all-around extrinsic base are grown on the base region.

A method includes forming a deep well region of a first conductivity type in a substrate, implanting a portion of the deep well region to form a first gate, and implanting the deep well region to form a well region. The well region and the first gate are of a second conductivity type opposite the first conductivity type. An implantation is performed to form a channel region of the first conductivity type over the first gate. A portion of the deep well region overlying the channel region is implanted to form a second gate of the second conductivity type. A source/drain implantation is performed to form a source region and a drain region of the first conductivity type on opposite sides of the second gate. The source and drain regions are connected to the channel region, and overlap the channel region and the first gate.

Structures for a cascode integrated circuit and methods of forming such structures. A field-effect transistor of the structure includes a gate electrode finger, a first source/drain region, and a second source/drain region. A bipolar junction transistor of the structure includes a first terminal, a base layer with an intrinsic base portion arranged on the first terminal, and a second terminal that includes one or more fingers arranged on the intrinsic base portion of the base layer. The intrinsic base portion of the base layer is arranged in a vertical direction between the first terminal and the second terminal. The first source/drain region is coupled with the first terminal, and the first source/drain region at least partially surrounds the bipolar junction transistor.