Abstract: A field effect transistor (FET) with an underlying airgap and methods of manufacture are disclosed. The method includes forming an amorphous layer at a predetermined depth of a substrate. The method further includes forming an airgap in the substrate under the amorphous layer. The method further includes forming a completely isolated transistor in an active region of the substrate, above the amorphous layer and the airgap.

Abstract: A field effect transistor (FET) with an underlying airgap and methods of manufacture are disclosed. The method includes forming an amorphous layer at a predetermined depth of a substrate. The method further includes forming an airgap in the substrate under the amorphous layer. The method further includes forming a completely isolated transistor in an active region of the substrate, above the amorphous layer and the airgap.

Abstract: Various embodiments include field effect transistors (FETs) and methods of forming such FETs. One method includes: forming a first set of openings in a precursor structure having: a silicon substrate having a crystal direction, the silicon substrate substantially abutted by a first oxide; a silicon germanium (SiGe) layer overlying the silicon substrate; a silicon layer overlying the SiGe layer; a second oxide overlying the silicon layer; and a sacrificial layer overlying the second oxide, wherein the first set of openings each expose the silicon substrate; undercut etching the silicon substrate in a direction perpendicular to the crystal direction of the silicon substrate to form a trench corresponding with each of the first set of openings; passivating exposed surfaces of at least one of the SiGe layer or the silicon layer in the first set of openings; and at least partially filling each trench with a dielectric.

Abstract: The disclosure relates to semiconductor structures and, more particularly, to structures for preventing dicing damage on photonics wafers. The structure includes: an optical waveguide structure to optical fiber interface formed on an integrated circuit; and a groove formed in a substrate and which includes a structure preventing a fluid pressure of a dicing operation from damaging the substrate along the groove.

Abstract: Various embodiments include field effect transistors (FETs) and related integrated circuit (IC) layouts. One FET includes: a silicon substrate including a set of trenches; a first oxide abutting the silicon substrate; a silicon germanium (SiGe) layer overlying the silicon substrate; a silicon layer overlying the SiGe layer; a second oxide overlying the silicon layer, wherein the silicon layer includes a plurality of salicide regions; a gate structure overlying the second oxide between adjacent salicide regions; and a first contact contacting the gate structure; a second contact contacting one of the salicide regions; a third oxide partially filling the set of trenches and extending above the silicon layer overlying the SiGe layer; and an air gap in each of the set of trenches, the air gap surrounded by the third oxide.

Abstract: A field effect transistor (FET) with an underlying airgap and methods of manufacture are disclosed. The method includes forming an amorphous layer at a predetermined depth of a substrate. The method further includes forming an airgap in the substrate under the amorphous layer. The method further includes forming a completely isolated transistor in an active region of the substrate, above the amorphous layer and the airgap.

Abstract: Device structure and fabrication methods for a bipolar junction transistor. One or more trench isolation regions are formed in a substrate to define a device region having a first width. A protect layer is formed on a top surface of the one or more trench isolation regions and a top surface of the device region. An opening is formed in the protect layer. The opening is coincides with the top surface of the first device region and has a second width that is less than or equal to the first width of the first device region. A base layer is formed that has a first section on the device region inside the first opening and a second section on the protect layer.

Abstract: Device structure and fabrication methods for a bipolar junction transistor. One or more trench isolation regions are formed in a substrate to define a device region having a first width. A protect layer is formed on a top surface of the one or more trench isolation regions and a top surface of the device region. An opening is formed in the protect layer. The opening is coincides with the top surface of the first device region and has a second width that is less than or equal to the first width of the first device region. A base layer is formed that has a first section on the device region inside the first opening and a second section on the protect layer.

Abstract: Device structures and fabrication methods for a heterojunction bipolar transistor. A first base layer is formed on a first device region of a substrate. A first emitter is formed that defines a first junction with the first base layer. A second base layer is formed on a second device region of a substrate. A second emitter is formed that defines a second junction with the second base layer. The first base layer and the second base layer differ in thickness, composition, concentration of an electrically-active dopant, or a combination thereof.

Abstract: Electrical fuses and methods for forming an electrical fuse. A semiconductor substrate is implanted to define a modified region in the semiconductor substrate. Trenches that surround the modified region and that penetrate into the semiconductor substrate to a depth greater than a depth of the modified region are formed in the modified region so as to define a fuse link of the electrical fuse. The substrate is removed from beneath the fuse link with a selective etching process that removes the semiconductor substrate with a first etch rate that is higher than a second etch rate of the modified region.

Abstract: Device structures and fabrication methods for a bipolar junction transistor. A first semiconductor layer is formed on a substrate containing a first terminal. An etch stop layer is formed on the first semiconductor layer, and a second semiconductor layer is formed on the etch stop layer. The second semiconductor layer is etched to define a second terminal at a location of an etch mask on the second semiconductor layer. A first material comprising the etch stop layer and a second material comprising the second semiconductor layer are selected such that the second material of the second semiconductor layer etches at a greater etch rate than the first material of the etch stop layer. The first semiconductor layer may be a base layer that is used to form an intrinsic base and an extrinsic base of the bipolar junction transistor.

Abstract: A method of making a semiconductor structure includes forming a trench through a shallow trench isolation (STI) structure and into a substrate, and forming a liner including an electrical insulator material on sidewalls of the trench. The method also includes forming a core including a high thermal conductivity material in the trench and on the liner, and forming a cap in the trench and on the core.

Abstract: Methods of forming bipolar device structures and bipolar device structures. An opening may be formed in a device layer of a silicon-on-insulator substrate that extends to a buried insulator layer of the silicon-on-insulator substrate. An intrinsic base layer may be grown within the device layer opening by lateral growth on opposite first and second sidewalls of the device layer bordering the opening. A first collector of a first bipolar junction transistor of the device structure may be formed at a first spacing from the first sidewall. A second collector of a second bipolar junction transistor of the device structure may be formed at a second spacing from the second sidewall. An emitter, which is shared by the first bipolar junction transistor and the second bipolar transistor, is formed inside the opening. Portions of the intrinsic base layer may supply respective intrinsic bases for the first and second bipolar junction transistors.

Abstract: Device structures for a bipolar junction transistor and methods of fabricating a device structure for a bipolar junction transistor. A first semiconductor layer is formed on a substrate, and a second semiconductor layer is formed on the first semiconductor layer. The first semiconductor layer, the second semiconductor layer, and the substrate are etched to define first and second emitter fingers from the second semiconductor layer and trenches in the substrate that are laterally positioned between the first and second emitter fingers. The first semiconductor layer may function as a base layer in the device structure.

Abstract: Device structure and fabrication methods for a bipolar junction transistor. An emitter layer is formed on a base layer and etched to form an emitter of the device structure. The emitter layer has a concentration of an element that varies as a function of the thickness of the emitter layer. The etch rate of the emitter layer varies as a function of the concentration of the element such that the emitter has a variable width over the thickness of the emitter layer.

Abstract: Device structure and fabrication methods for a bipolar junction transistor. A base layer is formed and an emitter is formed on a first portion of the base layer. A dopant-containing layer is deposited on a second portion of the base layer. Dopant is transferred from the dopant-containing layer into the second portion of the base layer to define an extrinsic base of the device structure.

Abstract: Electrical fuses and methods for forming an electrical fuse. A semiconductor substrate is implanted to define a modified region in the semiconductor substrate. Trenches that surround the modified region and that penetrate into the semiconductor substrate to a depth greater than a depth of the modified region are formed in the modified region so as to define a fuse link of the electrical fuse. The substrate is removed from beneath the fuse link with a selective etching process that removes the semiconductor substrate with a first etch rate that is higher than a second etch rate of the modified region.

Abstract: Disclosed are structures and methods of forming the structures so as to have a photodetector isolated from a substrate by stacked trench isolation regions. In one structure, a first trench isolation region is in and at the top surface of a substrate and a second trench isolation region is in the substrate below the first. A photodetector is on the substrate aligned above the first and second trench isolation regions. In another structure, a semiconductor layer is on an insulator layer and laterally surrounded by a first trench isolation region. A second trench isolation region is in and at the top surface of a substrate below the insulator layer and first trench isolation region. A photodetector is on the semiconductor layer and extends laterally onto the first trench isolation region. The stacked trench isolation regions provide sufficient isolation below the photodetector to allow for direct coupling with an off-chip optical fiber.

Abstract: Fabrication methods, device structures, and design structures for a bipolar junction transistor. An intrinsic base layer is formed on a semiconductor substrate, an etch stop layer is formed on the intrinsic base layer, and an extrinsic base layer is formed on the etch stop layer. A trench is formed that penetrates through the extrinsic base layer to the etch stop layer. The trench is formed by etching the extrinsic base layer selective to the etch stop layer. The first trench is extended through the etch stop layer to the intrinsic base layer by etching the etch stop layer selective to the intrinsic base layer. After the trench is extended through the etch stop layer, an emitter is formed using the trench.

Abstract: Disclosed are structures and methods of forming the structures so as to have a photodetector isolated from a substrate by stacked trench isolation regions. In one structure, a first trench isolation region is in and at the top surface of a substrate and a second trench isolation region is in the substrate below the first. A photodetector is on the substrate aligned above the first and second trench isolation regions. In another structure, a semiconductor layer is on an insulator layer and laterally surrounded by a first trench isolation region. A second trench isolation region is in and at the top surface of a substrate below the insulator layer and first trench isolation region. A photodetector is on the semiconductor layer and extends laterally onto the first trench isolation region. The stacked trench isolation regions provide sufficient isolation below the photodetector to allow for direct coupling with an off-chip optical fiber.