Transistor-based sensors and fabrication methods for a transistor-based sensor. A semiconductor layer is arranged over a substrate, and an interconnect structure is arranged over the semiconductor layer and the substrate. The semiconductor layer includes first sections composed of a semiconductor material, second sections composed of the semiconductor material, and cavities. The first sections have an alternating arrangement with the second sections in a lateral direction. The semiconductor material of the first sections is polycrystalline, and the semiconductor material of the second sections is single-crystal. First and second openings each extend in a vertical direction through the metallization levels of the interconnect structure to the semiconductor layer or through the substrate to the semiconductor layer. The first opening defines a first fluid inlet coupled to the cavities, and the second opening defines a first fluid outlet coupled to the cavities.

Device structures and fabrication methods for a bipolar junction transistor. A trench isolation region surrounds an active region that includes a collector. A base layer is arranged over the active region, and a semiconductor layer is arranged on the base layer. The semiconductor layer includes a stepped profile with a first section having a first width adjacent to the base layer and a second section having a second width that is less than the first width. An emitter is arranged on the second section of the semiconductor layer.

A method for manufacturing a self-aligned SiGe HBT device by nonselective epitaxy. An expected germanium concentration, an expected boron doping percent and an expected carbon concentration can be obtained within a wide range by low-temperature selective epitaxy of SiGe. However, due to the influences of different doping ratios on the selectivity of epitaxial growth, a desired impurity distribution can be obtained after repeated experiments when selective epitaxy is used for device research and development, thus, delaying the research and development progress. According to the method of the present disclosure, nonselective epitaxy is adopted in an extrinsic base region, so that a deposition layer can be monocrystalline or polycrystalline, process complexity is low, and device performance is good.

Provided is a high ruggedness HBT, including a first emitter cap layer and a second emitter cap layer formed between an emitter layer and an ohmic contact layer, or only an emitter cap layer is formed between them. When the first and second emitter cap layers are provided, bandgaps of the first or second emitter cap layer are changed, and the ruggedness of the HBT is improved. When an emitter cap layer is provided, an electron affinity of at least a portion of the emitter cap layer is less than or approximately equal to an electron affinity of the emitter layer, and the ruggedness of the HBT is improved.

The present disclosure relates to a bipolar transistor semiconductor device including: a substrate layer, a collector epitaxial layer supported by the substrate layer, a base region supported by a portion of the collector epitaxial layer, and an emitter region supported by a portion of the base region. The emitter region includes a polysilicon material.

The disclosure provides a high ruggedness HBT structure, including: a sub-collector layer on a substrate and formed of an N-type III-V semiconductor material; a collector layer on the sub-collector layer and formed of a III-V semiconductor material; a base layer on the collector layer and formed of a P-type III-V semiconductor material; an emitter layer on the base layer and formed of one of N-type semiconductor materials of InGaP, InGaAsP and InAlGaP; a first emitter cap layer on the emitter layer and formed of one of undoped or N-type semiconductor materials of Al.sub.xGa.sub.1-xAs, Al.sub.xGa.sub.1-xAs.sub.1-yN.sub.y, Al.sub.xGa.sub.1-xAs.sub.1-zP.sub.z, Al.sub.xGa.sub.1-xAs.sub.1-wSb.sub.w, and In.sub.rAl.sub.xGa.sub.1-x-rAs, x having a highest value between 0.05x0.4, and y, z, r, w0.1; a second emitter cap layer on the first emitter cap layer and formed of an N-type III-V semiconductor material; and an ohmic contact layer on the second emitter cap layer and formed of an N-type III-V semiconductor material.

A semiconductor device, such as a heterojunction bipolar transistor (HBT), may include an extrinsic base region that is connected to a collector region via semiconductor material formed in an opening in one or more dielectric layers interposed between the extrinsic base region and the collector region. The extrinsic base region may be formed from monocrystalline semiconductor material, such as silicon or silicon germanium, via selective epitaxial growth. An intrinsic base region may be formed adjacent to the extrinsic base region and may be interposed directly between the collector region and an intrinsic emitter region. A HBT with such an arrangement may have reduced base-collector capacitance and reduced base resistance compared to some conventional HBTs.

This specification discloses methods for integrating a SiGe-based HBT (heterojunction bipolar transistor) and a Si-based BJT (bipolar junction transistor) together in a single manufacturing process that does not add a lot of process complexity, and an integrated circuit that can be fabricated utilizing such a streamlined manufacturing process. In some embodiments, such an integrated circuit can enjoy both the benefits of a higher RF (radio frequency) performance for the SiGe HBT and a lower leakage current for the Si-based BJT. In some embodiments, such an integrated circuit can be applied to an ESD (electrostatic discharge) clamp circuit, in order to achieve a lower, or no, yield-loss.

Device structures and fabrication methods for a bipolar junction transistor. A trench isolation region surrounds an active region that includes a collector. A base layer is arranged over the active region, and a semiconductor layer is arranged on the base layer. The semiconductor layer includes a stepped profile with a first section having a first width adjacent to the base layer and a second section having a second width that is less than the first width. An emitter is arranged on the second section of the semiconductor layer.

A thin Ge layer is formed between an SiGe intrinsic base and single-crystal Si extrinsic base structures to greatly simplify the fabrication of raised-base SiGe heterojunction bipolar transistors (HBTs). The fabrication process includes sequentially depositing the SiGe intrinsic base, the Ge, and Si extrinsic base layers as single-crystal structures over a patterned silicon wafer while the wafer is maintained inside a reaction chamber. The Ge layer subsequently functions as an etch stop, and protects the crystallinity of the underlying SiGe intrinsic base material during subsequent dry etching of the Si extrinsic base layer, which is performed to generate an emitter window. A wet etch then removes residual Ge from the emitter window to expose a contact portion of the SiGe layer surface without damage. A polysilicon emitter structure is formed in the emitter window, and then salicide is formed over the base stacks to encapsulate the SiGe and Ge structures.