Abstract: The disclosure provides bipolar transistor structures with a semiconductor base film within an opening of an isolation layer, and related methods. A structure according to the disclosure includes a semiconductor base film on a collector terminal. The semiconductor base film includes a first portion within an opening of an isolation layer. The first portion includes an intrinsic semiconductor. A second portion of the semiconductor base film is on the first portion. The second portion includes a sidewall adjacent the isolation layer and a lower surface on the isolation layer. A semiconductor film is on an upper surface of the first portion of the isolation layer and adjacent a sidewall of the second portion of the isolation layer. An emitter is on the semiconductor film.

Abstract: An isolation stack for a bipolar transistor (BT), and related methods, are provided. A structure of the disclosure includes a first isolation layer on a subcollector. A first air gap is between the first isolation layer and a collector of a bipolar transistor (BT). A second isolation layer is on the first isolation layer and adjacent an intrinsic base of the BT. A second air gap is above the second isolation layer adjacent the intrinsic base of the BT and below an extrinsic base of the BT. The second isolation layer defines a physical boundary between the first air gap and the second air gap.

Abstract: The disclosure provides a structure base portions having different germanium concentrations, and related methods. A structure of the disclosure includes a base region including a first portion on a first emitter/collector (E/C) terminal and including germanium (Ge). A Ge concentration in the first portion varies with respect to distance from the first E/C terminal. A second portion is on the first portion and includes Ge. A third portion is between the second portion and a second E/C terminal and includes Ge. A Ge concentration in the third portion varies with respect to distance between the second portion and the second E/C terminal.

Abstract: The disclosure provides bipolar transistor structures with a semiconductor film, and related methods. A structure of the disclosure includes an intrinsic base on a collector. The collector has a first doping type. A semiconductor film is on the intrinsic base and horizontally surrounds the intrinsic base. The semiconductor film horizontally encapsulates the intrinsic base. An emitter having the first doping type is on a first portion of the semiconductor film. An extrinsic base having a second doping type is on a second portion of the semiconductor film.

Abstract: The disclosure provides an isolation stack for a bipolar transistor (BT), and related methods. A structure of the disclosure includes a first isolation layer on a subcollector. A first air gap is between the first isolation layer and a collector of a BT. A second isolation layer is on the first isolation layer and adjacent an intrinsic base of the BT. A third isolation layer is on the second isolation layer, vertically between the second isolation layer and an extrinsic base of the BT. A second air gap is adjacent the third isolation layer and below the extrinsic base.

Abstract: Disclosed are semiconductor structure embodiments of a semiconductor-on-insulator region on a bulk substrate. The semiconductor-on-insulator region includes an upper semiconductor layer above and physically separated from the substrate by insulator-containing cavities (e.g., by dielectric layer and/or a pocket of trapped air, of trapped gas, or under vacuum) and, optionally, by a lower semiconductor layer. Disclosed method embodiments include forming openings that extend vertically through the upper semiconductor layer, through a sacrificial semiconductor layer and, optionally, through a lower semiconductor layer to the substrate. Then, a selective isotropic etch process is performed to form cavities, which extend laterally off the sides of the openings into the sacrificial semiconductor layer.

Abstract: Structures for a microfluidic channel and methods of forming a structure for a microfluidic channel. The structure comprises a trench in a semiconductor substrate and a semiconductor layer inside the trench. The trench has an entrance and a sidewall extending from the entrance into the semiconductor substrate. The semiconductor layer has a first portion surrounding a portion of the trench to define a cavity and a second portion positioned to obstruct the entrance to the trench. The second portion of the semiconductor layer is thicker than the first portion of the semiconductor layer.

Abstract: Structures for a microfluidic channel and methods of forming a structure for a microfluidic channel. The structure comprises a trench in a semiconductor substrate and a semiconductor layer inside the trench. The trench has an entrance and a sidewall extending from the entrance into the semiconductor substrate. The semiconductor layer has a first portion surrounding a portion of the trench to define a cavity and a second portion positioned to obstruct the entrance to the trench. The second portion of the semiconductor layer is thicker than the first portion of the semiconductor layer.

Abstract: Disclosed are semiconductor structure embodiments of a semiconductor-on-insulator region on a bulk substrate. The semiconductor-on-insulator region includes an upper semiconductor layer above and physically separated from the substrate by insulator-containing cavities (e.g., by dielectric layer and/or a pocket of trapped air, of trapped gas, or under vacuum) and, optionally, by a lower semiconductor layer. Disclosed method embodiments include forming openings that extend vertically through the upper semiconductor layer, through a sacrificial semiconductor layer and, optionally, through a lower semiconductor layer to the substrate. Then, a selective isotropic etch process is performed to form cavities, which extend laterally off the sides of the openings into the sacrificial semiconductor layer.

Abstract: Disclosed are semiconductor structure embodiments of a semiconductor-on-insulator region on a bulk substrate. The semiconductor-on-insulator region includes an upper semiconductor layer above and physically separated from the substrate by insulator-containing cavities (e.g., by dielectric layer and/or a pocket of trapped air, of trapped gas, or under vacuum) and, optionally, by a lower semiconductor layer. Disclosed method embodiments include forming openings that extend vertically through the upper semiconductor layer, through a sacrificial semiconductor layer and, optionally, through a lower semiconductor layer to the substrate. Then, a selective isotropic etch process is performed to form cavities, which extend laterally off the sides of the openings into the sacrificial semiconductor layer.

Abstract: Methods of forming structures with electrical isolation. A dielectric layer is formed over a semiconductor substrate, openings are patterned in the dielectric layer that extend to the semiconductor substrate, and a semiconductor material is epitaxially grown from portions of the semiconductor substrate that are respectively exposed inside the openings. The semiconductor material, during growth, defines a semiconductor layer that includes first portions respectively coincident with the openings and second portions that laterally grow from the first portions to merge over a top surface of the dielectric layer. A modified layer containing a trap-rich semiconductor material is formed in the semiconductor substrate.

Abstract: Methods of forming structures with electrical isolation. A dielectric layer is formed over a semiconductor substrate, openings are patterned in the dielectric layer that extend to the semiconductor substrate, and a semiconductor material is epitaxially grown from portions of the semiconductor substrate that are respectively exposed inside the openings. The semiconductor material, during growth, defines a semiconductor layer that includes first portions respectively coincident with the openings and second portions that laterally grow from the first portions to merge over a top surface of the dielectric layer. A modified layer containing a trap-rich semiconductor material is formed in the semiconductor substrate.

Abstract: Disclosed are semiconductor structure embodiments of a semiconductor-on-insulator region on a bulk substrate. The semiconductor-on-insulator region includes an upper semiconductor layer above and physically separated from the substrate by insulator-containing cavities (e.g., by dielectric layer and/or a pocket of trapped air, of trapped gas, or under vacuum) and, optionally, by a lower semiconductor layer. Disclosed method embodiments include forming openings that extend vertically through the upper semiconductor layer, through a sacrificial semiconductor layer and, optionally, through a lower semiconductor layer to the substrate. Then, a selective isotropic etch process is performed to form cavities, which extend laterally off the sides of the openings into the sacrificial semiconductor layer.

Abstract: Fabrication methods and device structures for a heterojunction bipolar transistor. A trench isolation region is formed that surrounds an active region of semiconductor material, a collector is formed in the active region, and a base layer is deposited that includes a first section over the trench isolation region, a second section over the active region, and a third section over the active region that connects the first section and the second section. An emitter is arranged over the second section of the base layer, and an extrinsic base layer is arranged over the first section of the base layer and the third section of the base layer. The extrinsic base layer includes a first section containing polycrystalline semiconductor material and a second section containing single-crystal semiconductor material. The first and second sections of the extrinsic base layer intersect along an interface that extends over the trench isolation region.

Abstract: Structures that integrate airgaps with a field-effect transistor and methods for forming a field-effect transistor with integrated airgaps. A first semiconductor layer is formed on a substrate, and a second semiconductor layer is formed over the first semiconductor layer. A source/drain region of a field-effect transistor is formed in the second semiconductor layer. An airgap is located in the first semiconductor layer, The airgap is arranged in a vertical direction between the source/drain region and the substrate.

Abstract: Fabrication methods and device structures for a heterojunction bipolar transistor. A trench isolation region is formed that surrounds an active region of semiconductor material, a collector is formed in the active region, and a base layer is deposited that includes a first section over the trench isolation region, a second section over the active region, and a third section over the active region that connects the first section and the second section. An emitter is arranged over the second section of the base layer, and an extrinsic base layer is arranged over the first section of the base layer and the third section of the base layer. The extrinsic base layer includes a first section containing polycrystalline semiconductor material and a second section containing single-crystal semiconductor material. The first and second sections of the extrinsic base layer intersect along an interface that extends over the trench isolation region.

Abstract: Structures that integrate airgaps with a field-effect transistor and methods for forming a field-effect transistor with integrated airgaps. A first semiconductor layer is formed on a substrate, and a second semiconductor layer is formed over the first semiconductor layer. A source/drain region of a field-effect transistor is formed in the second semiconductor layer. An airgap is located in the first semiconductor layer, The airgap is arranged in a vertical direction between the source/drain region and the substrate.