Abstract: Integrated circuits with stressed transistors are provided. Stressing transistors may increase transistor threshold voltage without the need to increase channel doping. Stressing transistors may reduce total leakage currents. It may be desirable to compressively stress N-channel metal-oxide-semiconductor (NMOS) transistors and tensilely stress P-channel metal-oxide-semiconductor (PMOS) transistors to reduce leakage currents. Techniques that can be used to alter the amount of stressed experienced by transistors may include forming a stress-inducing layer, forming a stress liner, forming diffusion active regions using silicon germanium, silicon carbon, or standard silicon, implementing transistors in single-finger instead of multi-finger configurations, and implanting particles. Any combination of these techniques may be used to provide appropriate amounts of stress to increase the performance or decrease the total leakage current of a transistor.

Abstract: Asymmetric transistors such as asymmetric pass transistors may be formed on an integrated circuit. The asymmetric transistors may have gate structures. Symmetric pocket implants may be formed in source-drains on opposing sides of each transistor gate structure. Selective heating may be used to asymmetrically diffuse the implants. Selective heating may be implemented by patterning the gate structures on a semiconductor substrate so that the spacing between adjacent gate structures varies. A given gate structure may be located between first and second adjacent gate structures spaced at different respective distances from the given gate structure. A larger gate structure spacing leads to a greater substrate temperature rise than a smaller gate structure spacing. The pocket implant diffuses more in portions of the substrate with the greater temperature rise, producing asymmetric transistors.

Abstract: Nonvolatile memory element circuitry is provided that is based on metal-oxide-semiconductor transistor structures. A nonvolatile memory element may be based on a metal-oxide-semiconductor transistor structure that has a gate, a drain, a source, and a body. During programming operations, control circuitry floats the body while applying a positive voltage to the drain and a negative voltage to the source. This causes the drain and source, which serve as the collector and emitter in a parasitic bipolar transistor, to break down. The drain-to-source (collector-to-emitter) breakdown causes sufficient current to flow through the source to alter the source electrode and thereby increase the resistance of the source significantly. During sensing operations, control circuitry may apply a voltage across the drain and source while grounding the body to determine whether the memory element has been programmed.

Abstract: An integrated circuit with memory elements is provided. The memory elements may have memory element transistors with body terminals. Body bias control circuitry may supply body bias voltages that strengthen or weaken memory element transistors to improve read and write margins. The body bias control circuitry may dynamically control body bias voltages so that time-varying body bias voltages are supplied to memory element transistors. Address transistors and latch transistors in the memory elements may be selectively strengthened and weakened. Process variations may be compensated by weakening fast transistors and strengthening slow transistors with body bias adjustments.

Abstract: A method for improving analog circuits performance using a circuit design using forward bias and a modified mixed-signal process is presented. A circuit consisting plurality of NMOS and PMOS transistors is defined. The body terminal of the NMOS transistors are coupled to a first voltage source and the body terminal of the PMOS transistors are coupled a second voltage source. Transistors in the circuit are selectively biased by applying the first voltage source to the body terminal of each selected NMOS transistor and applying the second voltage source to the body terminal of each selected PMOS transistor. In one embodiment, the first voltage source and the second voltage source are modifiable to provide forward and reverse bias to the body terminal of the transistors.

Abstract: An integrated circuit is provided with groups of transistors that handle different maximum voltage levels. The transistors may be metal-oxide-semiconductor transistors having body, source, drain, and gate terminals. The gate of each transistor may have a gate insulator and a gate conductor. The gate conductor may be formed from a semiconductor such as polysilicon. Adjacent to the gate insulator, the polysilicon gate conductor may have a depletion layer. The depletion layer may have a thickness that is related to the doping level in the polysilicon gate conductor. By reducing the doping level in the polysilicon gates of some of the transistors, the equivalent oxide thickness of those transistors is increased, thereby enhancing their ability to withstand elevated voltages without experiencing gate oxide breakdown due to hot carrier injection effects.

Abstract: Metal-oxide-semiconductor transistors are provided. A metal-oxide-semiconductor transistor may be formed on a semiconductor substrate. Source and drain regions may be formed in the substrate. A gate insulator such as a high-K dielectric may be formed between the source and drain regions. A gate may be formed from multiple gate conductors. The gate conductors may be metals with different workfunctions. A first of the gate conductors may form a pair of edge gate conductors that are adjacent to dielectric spacers. An opening between the edge gate conductors may be filled with the second gate conductor to form a center gate conductor. A self-aligned gate formation process may be used in fabricating the metal-oxide-semiconductor transistor.

Abstract: Mixed gate metal-oxide-semiconductor transistors are provided. The transistors may have an asymmetric configuration that exhibits increased output resistance. Each transistor may be formed from a gate insulating layer formed on a semiconductor. The gate insulating layer may be a high-K material. Source and drain regions in the semiconductor may define a transistor gate length. The gate length may be larger than the minimum specified by semiconductor fabrication design rules. The transistor gate may be formed from first and second gate conductors with different work functions. The relative sizes of the first and gate conductors in a given transistor control the threshold voltage for the transistor. A computer-aided design tool may be used to receive a circuit design from a user. The tool may generate fabrication masks for the given design that include mixed gate transistors with threshold voltages optimized to meet circuit design criteria.

Abstract: Metal-oxide-metal capacitors with bar vias are provided for integrated circuits. The capacitors may be formed in the interconnect layers of integrated circuits. Stacked bar vias and metal lines in the interconnect layers may be connected to form conductive vertical plates that span multiple interconnect layers. The capacitors with bar vias may be formed by placing multiple vertical plates formed from stacked bar vias and metal lines parallel to each other, alternating the polarity of adjacent vertical parallel plates to form multiple parallel plate capacitors. The parallel plates may be interconnected to form first and second terminals in a capacitor.

Abstract: A method for improving analog circuits performance using a circuit design using forward bias and a modified mixed-signal process is presented. A circuit consisting plurality of NMOS and PMOS transistors is defined. The body terminal of the NMOS transistors are coupled to a first voltage source and the body terminal of the PMOS transistors are coupled a second voltage source. Transistors in the circuit are selectively biased by applying the first voltage source to the body terminal of each selected NMOS transistor and applying the second voltage source to the body terminal of each selected PMOS transistor. In one embodiment, the first voltage source and the second voltage source are modifiable to provide forward and reverse bias to the body terminal of the transistors.

Abstract: A varactor may have a first terminal connected to a gate. The gate may be formed from a p-type polysilicon gate conductor. The gate may also have a gate insulator formed from a layer of insulator such as silicon oxide. The gate insulator may be located between the gate conductor and a body region. Source and drain contact regions may be formed in a silicon body region. The body region and the source and drain may be doped with n-type dopant. The varactor may have a second terminal connected to the n-type source and drain. A control voltage may be used to adjust the level of capacitance produced by the varactor between the first and second terminals. A positive control voltage may produce a larger capacitance than a negative control voltage. Application of the negative control voltage may produce a depletion layer in the p+ polysilicon gate layer.