Abstract: Systems, methods, and apparatus for an improved body tie construction are described. The improved body tie construction is configured to have a lower resistance body tie exists when the transistor is “off” (Vg approximately 0 volts). When the transistor is “on” (Vg>Vt), the resistance to the body tie is much higher, reducing the loss of performance associated with presence of body tie. Space efficient Body tie constructions adapted for cascode configurations are also described.

Abstract: Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are possible where the amplifier is configured to operate in at least an active mode and a standby mode. Circuital arrangements can reduce bias circuit and stacked transistors standby current during operation in the standby mode and to reduce impedance presented to the gates of the stacked transistors during operation in the active mode while maintaining voltage compliance of the stacked transistors during both modes of operation.

Abstract: FET designs that exhibit low leakage in the presence of the edge transistor phenomenon. Embodiments includes nFET designs in which the work function ?MF of the gate structure overlying the edge transistors of the nFET is increased by forming extra P+ implant regions within at least a portion of the gate structure, thereby increasing the Vt of the edge transistors to a level that may exceed the Vt of the central conduction channel of the nFET. In some embodiments, the gate structure of the nFET is modified to increase or “flare” the effective channel length of the edge transistors relative to the length of the central conduction channel of the FET. Other methods of changing the work function ?MF of the gate structure overlying the edge transistors are also disclosed. The methods may be adapted to fabricating pFETs by reversing or substituting material types.

Abstract: Structures and methods for better optimizing the performance of all the circuitry of an SOI IC. Embodiments include SOI IC having dual-thickness active areas, such that digital and non-RF analog circuitry may be fabricated on a relatively thin active layer while RF circuitry may be fabricated on a relatively thick active layer. Fabrication of RF circuitry on the relatively thick active layer allows for improvements to the RON*COFF figure of merit for the FET devices, and for optimizations not feasible for RF circuitry fabricated on a relatively thin active layer. Structures and methods for two-level shallow-trench isolation (STI) structures and electrical contacts are disclosed. Some embodiments may include a substrate contact extending from the substantially planar upper surface of a dielectric layer overlaying the thin and thick active areas to at least the BOX layer.

Abstract: A transistor stack can include a combination of floating and body tied devices. Improved performance of the RF amplifier can be obtained by using a single body tied device as the input transistor of the stack, or as the output transistor of the stack, while other transistors of the stack are floating transistors. Transient response of the RF amplifier can be improved by using all body tied devices in the stack.

Abstract: Integrated circuit structures that significantly reduce the resistance associated with the body contact region and substrate region contact of a field-effect transistor (FET) compared to conventional designs. Embodiments include a FET having a body contact region, and optionally a substrate region contact, that includes germanium (Ge) alone or as an alloy with silicon (SiGe) and/or as a layered combination with silicon (e.g., a layer of Ge on a layer of Si). A first method includes fabricating a body contact region of a field-effect transistor by fabricating the field-effect transistor with an Si body contact region, and diffusing or implanting Ge within the Si. A second method includes fabricating a body contact region of a field-effect transistor by fabricating the field-effect transistor with an Si body contact region, etching away at least part of the Si body contact region to form a well, and depositing Ge within the well.

Abstract: Methods and structures for mitigating back-gate effects in a radio frequency (RF) silicon-on-insulator (SOI) substrate, RF-SOI, are presented. According to one aspect, a first implant or junction is formed in a region of a trap-rich layer (TRL) of the RF-SOI that is located below a first circuit/device to protect. The first implant or junction is fully contained within the TRL. A planar surface area of the first implant and/or junction fully contains a projection of a planar surface area of the first circuit and/or device. The first implant or junction is biased via a through BOX contact (TBC) that penetrates the BOX layer at a shallow trench isolation region formed in the RF-SOI. According to another aspect, a second implant or junction is formed in a region of the TRL below a second circuit/device. The first and second implants or junctions are disjoint and separated by an undoped region of the TRL.

Abstract: Systems, methods, and apparatus for an improved body tie construction are described. The improved body tie construction is configured to have a lower resistance body tie exists when the transistor is “off” (Vg approximately 0 volts). When the transistor is “on” (Vg>Vt), the resistance to the body tie is much higher, reducing the loss of performance associated with presence of body tie. Space efficient Body tie constructions adapted for cascode configurations are also described.

Abstract: Three-dimensional (3-D) integrated circuit structures and circuits that enable high performance FET switch arrays while consuming less planar area than conventional 2-D IC dies. In one embodiment, an integrated FET switch circuit includes a first wafer/die including a first set of groups of FET cells, and a second wafer/die joined to the first wafer/die through hybrid bonding interconnects and including a second set of groups of FET cells, wherein a first side drain bus of each group in the first wafer/die is connected through the hybrid bonding interconnects to a second side source bus of a first corresponding group in the second wafer/die; and wherein a second side source bus of each group in the first wafer/die is connected through the hybrid bonding interconnects to a first side drain bus of a second corresponding group in the second wafer/die.

Abstract: Electronic circuits and methods encompassing an RF switch comprising a plurality of series-coupled (stacked) integrated circuit (IC) SOI MOSFETs having a distributed back-bias network structure comprising groups of substrate contacts coupled to a bias voltage source through a resistive ladder. The distributed back-bias network structure sets the common IC substrate voltage at a fixed DC bias but resistively decouples groups of MOSFETs with respect to RF voltages so that the voltage division characteristics of the MOSFET stack are maintained. The distributed back-bias network structure increases the voltage handling capability of each MOSFET and improves the maximum RF voltage at which a particular MOSFET is effective as a switch device, while mitigating loss, leakage, crosstalk, and distortion. RF switches in accordance with the present invention are particularly useful as antenna switches.

Abstract: Systems, methods, and apparatus for an improved protection from charge injection into layers of a device using resistive structures are described. Such resistive structures, named s-contacts, can be made using simpler fabrication methods and less fabrication steps. In a case of metal-oxide-semiconductor (MOS) field effect transistors (FETs), s-contacts can be made with direct connection, or resistive connection, to all regions of the transistors, including the source region, the drain region and the gate.

Abstract: Structures and methods for better optimizing the performance of all the circuitry of an SOI IC. Embodiments include SOI IC having dual-thickness active areas, such that digital and non-RF analog circuitry may be fabricated on a relatively thin active layer while RF circuitry may be fabricated on a relatively thick active layer. Fabrication of RF circuitry on the relatively thick active layer allows for improvements to the RON*COFF figure of merit for the FET devices, and for optimizations not feasible for RF circuitry fabricated on a relatively thin active layer. Two methods of forming shallow-trench isolation (STI) structures in both active layers are described. A first method forms STIs in the thin active layer first, then in the thick active layer. A second method forms STIs in the thin active layer first and partial STIs in the thick active layer, then completes the partial STIs in the thick active layer.

Abstract: A high-voltage switching device that can be fabricated in a standard low-voltage process, such as CMOS, and more specifically SOI CMOS. Embodiments include integrated circuits that combine, in a unitary structure, a FET device and an integrated, co-fabricated modulated resistance region (MRR) controlled by one or more Voltage-Drop Modulation Gates (VDMGs). The VDMGs are generally biased independently of the gate of the FET device, and in such a way as to protect each VDMG from excessive and potentially destructive voltages. In a first embodiment, an integrated circuit high voltage switching device includes a transistor structure including a source, a gate, and an internal drain; an MRR connected to the internal drain of the transistor structure; at least one VDMG that controls the resistance of the MRR; and a drain electrically connected to the MRR. Each VDMG at least partially depletes the MRR upon application of a bias voltage.

Abstract: Methods and devices to address body leakage current generation and bias voltage distribution associated with body leakage current in an OFF state of a FET switch stack are disclosed. The devices include charge redistribution arrangements and bridge networks to perform coupling/decoupling to/from the FET switch stack. Detailed structures of such bridge networks are also described.

Abstract: Integrated circuits (ICs) that avoid or mitigate creation of changes in accumulated charge in a silicon-on-insulator (SOI) substrate, particularly an SOI substrate having a trap rich layer. In one embodiment, a FET is configured such that, in a standby mode, the FET is turned OFF while maintaining essentially the same VDS as during an active mode. In another embodiment, a FET is configured such that, in a standby mode, current flow through the FET is interrupted while maintaining essentially the same VGS as during the active mode. In another embodiment, a FET is configured such that, in a standby mode, the FET is switched into a very low current state (a “trickle current” state) that keeps both VGS and VDS close to their respective active mode operational voltages. Optionally, S-contacts may be formed in an IC substrate to create protected areas that encompass FETs that are sensitive to accumulated charge effects.

Abstract: Methods and devices to address the undesired DC voltage distribution across switch stacks in OFF state are disclosed. The disclosed devices include charge control elements that sample the RF signal to generate superimposed voltages at specific points of the switch stack biasing circuit. The provided voltages help reducing the drooping voltages on drain/source/body terminals of the transistors within the stack by supplying the current drawn by drain/source terminals of the stacked transistors and/or by sinking the body leakage current exiting the body terminals of such transistors. Methods and techniques teaching how to provide proper tapping points in the biasing circuit to sample the RF signal are also disclosed.

Abstract: Systems, methods, and apparatus for an improved protection from charge injection into layers of a device using resistive structures are described. Such resistive structures, named s-contacts, can be made using simpler fabrication methods and less fabrication steps. In a case of metal-oxide-semiconductor (MOS) field effect transistors (FETs), s-contacts can be made with direct connection, or resistive connection, to all regions of the transistors, including the source region, the drain region and the gate.

Abstract: FET designs that exhibit low leakage in the presence of the edge transistor phenomenon. Embodiments includes nFET designs in which the work function ?MF of the gate structure overlying the edge transistors of the nFET is increased by forming extra P+ implant regions within at least a portion of the gate structure, thereby increasing the Vt of the edge transistors to a level that may exceed the Vt of the central conduction channel of the nFET. In some embodiments, the gate structure of the nFET is modified to increase or “flare” the effective channel length of the edge transistors relative to the length of the central conduction channel of the FET. Other methods of changing the work function ?MF of the gate structure overlying the edge transistors are also disclosed. The methods may be adapted to fabricating pFETs by reversing or substituting material types.

Abstract: FET designs, and in particular NMOSFET designs based on SOI fabrication technology, that exhibit low leakage in the presence of the edge transistor phenomenon. Embodiments include FETs in which the threshold voltage VTE of the edge FETs is increased to a level that is at least equal to the threshold voltage VTC of the central conduction channel FET using a novel dual work function configuration of a high dielectric constant (high-?) replacement metal gate (RMG) structure. One embodiment encompasses a FET including an RMG structure overlying a doped silicon region, the RMG structure including: an interface insulator formed over the doped silicon region; a high-? material formed over the interface insulator; an N-type work function material overlaying and in contact with a central portion of the high-? material; and a P-type work function material overlaying and in contact with at least one edge portion of the high-? material.

Abstract: Methods and devices to address the undesired DC voltage distribution across switch stacks in OFF state are disclosed. The disclosed devices include charge control elements that sample the RF signal to generate superimposed voltages at specific points of the switch stack biasing circuit. The provided voltages help reducing the drooping voltages on drain/source/body terminals of the transistors within the stack by supplying the current drawn by drain/source terminals of the stacked transistors and/or by sinking the body leakage current exiting the body terminals of such transistors. Methods and techniques teaching how to provide proper tapping points in the biasing circuit to sample the RF signal are also disclosed.