Altera Corporation

Altera Corporaton

Jeffrey Xiaoqi Tung

Qi Xiang

Jun Liu

Albert Ratnakumar

Irfan Rahim

Andy Louie Lee

Jeffrey T Watt

Yanzhong Xu

Srinivas Perisetty

Shankar Sinha

Shih-Lin S Lee

Ning Cheng

Fangyun Richter

Che Ta Hsu

Wilson Wong

Weiqi Ding

William Bradley Vest

Charles Chu

Lu Zhou

Mao Du

Yanzhong Yu

Asymmetric transistors may be formed by creating pocket implants on one source-drain terminal of a transistor and not the other. Asymmetric transistors may also be formed using dual-gate structures having first and second gate conductors of different work functions. Stacked transistors may be formed by stacking two transistors of the same channel type in series. One of the source-drain terminals of each of the two transistors is connected to a common node. The gates of the two transistors are also connected together. The two transistors may have different threshold voltages. The threshold voltage of the transistor that is located higher in the stacked transistor may be provided with a lower threshold voltage than the other transistor in the stacked transistor. Stacked transistors may be used to reduce leakage currents in circuits such as memory cells. Asymmetric transistors may also be used in memory cells to reduce leakage.

Integrated circuits with asymmetric and stacked transistors

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.

Method of fabricating integrated circuit transistors with multipart gate conductors

In an illustrative embodiment, holes are formed in an insulating layer where the gates of NMOS and PMOS transistors are to be formed; and a hard mask spacer layer is formed on the exposed surfaces. Next, spacers are formed on the sidewalls of the holes by anisotropically etching the spacer layer to remove the portion of the spacer layer exposed at the bottom of each hole while leaving some of the spacer layer formed on the sidewalls of the holes. A high-k dielectric layer is then formed between the spacers; and a metal layer is formed on the high-k dielectric layer. Bulk metal layer is then formed on the metal layer. Chemical mechanical polishing is performed to remove the bulk gate metal down to the insulating layer, thereby isolating individual NMOS and PMOS gate structures.

High-k dielectric device and process

An insulating layer is formed on a semiconductor substrate; and holes are patterned in the insulating layer where transistor gates are to be formed. A hard mask spacer layer is formed on the upper surface of the insulating layer and the holes. Next, the spacer layer is anisotropically etched to remove the portion of the spacer layer exposed at the bottom of each hole as well as the portion of the spacer layer on the upper surface of the insulating layer. However, the etching process does not remove all of the portion of the spacer layer formed on the substantially vertical sidewalls of the holes. A high-k dielectric layer is then formed on the remaining vertical portion of the spacer layer and on the exposed upper surfaces of the substrate and the insulating layer. A metal layer is then formed on the high-k dielectric layer; and individual gate structures are completed.

Integrated circuit transistors with multipart gate conductors

Integrated circuits such as programmable integrated circuits may have configuration random-access memory elements. The configuration random-access memory elements may be loaded with configuration data to customize programmable circuitry on the integrated circuits. Each memory element may have a bistable element that is powered using a positive power supply voltage and a negative power supply voltage. Programmable transistors in the programmable circuitry may have gates coupled to outputs of the bistable elements. The programmable transistors may have gate insulators that are thinner than gate insulators in the transistors of the bistable elements and may have threshold voltages of about zero volts. During operation, some of the configuration random-access memory elements may supply negative voltages to their associated programmable transistors so that the programmable transistors are provided with gate-source voltages of less than zero volts.

Programmable integrated circuit with thin-oxide passgates

Circuits and techniques for operating a memory cell on an integrated circuit (IC) are disclosed. A disclosed memory cell includes a first inverter coupled to a second inverter to form a first connection and a second connection. The first connection is operable to receive at least a first data signal at a first voltage and the second connection is operable to receive at least a second data signal at a second voltage. A first oxide capacitor and a second oxide capacitor are coupled to the first and second connections respectively. Both the first and second oxide capacitors are coupled to receive a programming signal at a third voltage that may be operable to rupture either one of the first or second oxide capacitor.

Circuits and methods for hardening volatile memory circuits through one time programming

Mixed gate varactors are provided. The mixed gate varactors may include a semiconductor region of a given doping type. A first terminal for the varactor may be formed from a gate structure on the semiconductor region. A second terminal for the varactor may be formed from a heavily doped region in the semiconductor region that has the same doping type as the given doping type. A third terminal for the varactor may be formed from a heavily doped region in the semiconductor region that has a different doping type than the given doping type. The gate structure may include multiple gate conductors on a gate insulator. The gate insulator may be a high-K dielectric. The gate conductors may be metals or other materials that have different work functions. A conductive layer such as a layer of polysilicon may electrically connect the first and second gate conductors.

Mixed-gate metal-oxide-semiconductor varactors

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.

Stressed transistors with reduced leakage

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.

Memory elements with body bias control

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.

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Milpitas, CA, United States of America

Jeffrey Xiaoqi Tung