Integrated Device Technology, Inc.

Mosys, Inc.

Cadence Design Systems, Inc.

Jeong Yeol Choi

Chuen-Der Lien

Chung-Chyung Han

Chung-Jen Chien

Lifeng Wu

Alvin Chen

Zhihong Liu

Bruce W McGaughy

Stephen Fung

Zhijian Ma

Ken-Chuen Mui

Cheun-Der Lien

Fu-Chieh Hsu

Shih-Ked Lee

Sang-Yun Lee

Chunbo Liu

Long-Ching Wang

Jae Hong Jeong

Jeng-Jiun Yang

Ping F Chen

Kyle W Terrill

Tsengyou Syau

Guo-Qiang (Patrick) Lo

Chung Chyung Han

Pao-Lu Louis Huang

Jingkun Fang

Gang Zhang

Pauli Hsueh

Kuilong Wang

Ohm-Guo Pan

Yingbo Jia

An embedded memory system includes an array of random access memory (RAM) cells, on the same substrate as an array of logic transistors. Each RAM cell includes an access transistor and a capacitor structure. The capacitor structure is fabricated by forming a metal-insulator-metal capacitor in a dielectric layer. The embedded RAM system includes fewer metal layers in the memory region than in the logic region.

System with logic and embedded MIM capacitor

Method of forming a MIM capacitor

A method of forming an embedded DRAM cell having multiple-thickness gate dielectrics. An oxidation-enhancing dopant is selectively implanted into a well region in an area that is exposed by a first mask. A thermal oxidation step simultaneously produces the field dielectric for two distinct devices each having a different oxide thickness. The method is applicable to quad-density DRAM cells using fewer oxidation steps. The method is also applicable to planar DRAM cells, and does not require increasing the number of masks during the fabrication of planar DRAM cells.

Embedded DRAM with multiple gate oxide thicknesses

A method and apparatus for selectively restoring data in a non-volatile memory array based on failure type. Weakened data and erroneous data are identified by performing two readings of a specific memory section. Alternatively, an error correction code is used after a first reading of data to identify erroneous data. The manner in which data is restored will depend on whether the data changed because of an erase failure or a program failure. If only a program failure occurred then the data will be reprogrammed without an intervening erase step. If the data experienced an erase failure, then the data will be erased prior to being programmed with correct data.

Method and apparatus for restoring data in a non-volatile memory

An embedded memory system that includes DRAM cells and logic transistors. The capacitor of the embedded memory responds to a positive bias voltage of &#xbd; Vdd. The wordline driver of a p-channel access transistor applying the positive power supply voltage when the p-channel access FET is not being accessed and a voltage lower than the threshold voltage of the p-channel access FET is being accessed. For DRAM cells containing an n-channel access FET, the wordline driver applies either a negative voltage or the ground voltage to the n-channel access FET when the DRAM cell is not being accessed. A second voltage composed of Vdd and a boosted voltage is applied to the n-channel FET when the DRAM cell is being accessed.

Embedded DRAM with bias-independent capacitance

Data restoration method for a non-volatile memory

The present invention is directed to a number of improvements in methods for reliability simulations in aged circuits whose operation has been degraded through hot-carrier or other effects. A plurality of different circuit stress times can be simulated within a single run. Different aging criteria may be used for different circuit blocks, circuit block types, devices, device models and device types. The user may specify the degradation of selected circuit blocks, circuit block types, devices, device models and device types independently of the simulation. Device degradation can be characterized in tables. Continuous degradation levels can be quantized. Techniques are also described for representing the aged device in the netlist as the fresh device augmented with a plurality of independent current sources connected between its terminals to mimic the effects of aging in the device. The use of device model cards with age parameters is also described. To further improve the circuit reliability simulation, a gradual or multi-step aging is used instead of the standard one step aging process. Many of these features can be embedded within the circuit simulator. A user data interface is also presented to implement these techniques and further allow users to enter their device models not presented in the simulator. For example, a proprietary model of, say, the substrate current in an NMOS could used be with a SPICE simulator employing a different model to simulate the aging of the circuit.

Hot carrier circuit reliability simulation

The present invention is directed to a number of improvements in methods for hot-carrier device degradation modeling and extraction. Several improvements are presented for the improvement of building device degradation models, including allowing the user to select a device parameter used to build the device degradation model independent of the device parameter selected. The user can also select the functional relation between stress time and degradation level. To further improve accuracy, multiple acceleration parameters can be used to account for different regions of the degradation process. Analytical functions may be used to represent aged device model parameters, either directly or by fitting measured device parameters versus device age values, allowing devices with different age values to share the same device model. The concept of binning is extended to include device degradation. In addition to a binning based on device width and length, age is added. In an exemplary embodiment, only devices with minimum channel length have degraded models constructed. The present invention also allows the degradation of one device parameter to be determined based on an age value derived from another parameter. In yet another aspect, a degraded device is modeled as a fresh device with a voltage source connected to a terminal.

Hot-carrier device degradation modeling and extraction methodologies

A photomask and a method for forming a photomask are disclosed in which die regions that define features for a process step of a semiconductor fabrication process are formed on a photomask and a test pattern for a different process step is formed in a blading area of the photomask. Also, a method for forming test structures is disclosed in which the photomask is exposed to transfer the test pattern to a semiconductor substrate. The process step that is associated with the test pattern is then performed, forming a test structure on the semiconductor substrate. By utilizing blading areas of photomasks and including test patterns for different process steps on the same photomask, more test structures can be obtained, without the need to generate additional photomasks for testing purposes.

Method for forming photomask having test patterns in blading areas

The present invention is directed to methods for reliability simulations in aged circuits whose operation has been degraded through hot-carrier or other effects by allowing design rules on degradation to be included in the netlist. Once the hot-carrier circuit simulation is launched, the rules are checked and the reliability design rule violations are reported. The process can be performed on either the layout or schematic window. The design rule criteria can be any device parameter and can be expressed in absolute or relative terms. The criteria can be based on device type, model card name, instance geometry, or temperature. Additionally, values can be set prior to beginning the simulation.

Hot-carrier reliability design rule checker

A method for forming self-aligned contact devices in a core region of a semiconductor substrate and non-self-aligned contact devices in a non-core region of the semiconductor substrate is disclosed in which a single gate film stack is used for forming gate structures in both the core region and in the non-core region. A dielectric layer is formed over a semiconductor substrate and a gate film stack is formed over the dielectric layer. The gate film stack is then patterned so as to form gate structures within both the core region and the non-core region.

Method for forming hybrid device gates

Methods, apparatus and computer program products for modeling integrated circuits having dense devices therein that experience linewidth (e.g., gate electrodes) reductions during fabrication are provided. For dense devices having electrical paths therein and first and second gate electrodes that overlie the electrical path, operations include determining an electrical gate length of the first gate electrode by evaluating a change in current through the electrical path relative to a change in gate length of the second gate electrode. The operation to determine the electrical gate length of the first gate electrode includes evaluating a change in simulated drain-to-source current through the electrical path relative to a change in the electrical gate length of the second gate electrode.

Methods, apparatus and computer program products for modeling integrated circuit devices having reduced linewidths

A static random access memory (SRAM) cell is given increased stability and latch-up immunity by fabricating the PMOS load transistors of the SRAM cell to have a very low drain/source dopant concentration. The drain/source regions of the PMOS load transistors are formed entirely by a P&#x2212;&#x2212; blanket implant. The PMOS load transistors are masked during subsequent implant steps, such that the drain/source regions of the PMOS load transistors do not receive additional P-type (or N-type) dopant. The P&#x2212;&#x2212; blanket implant results in PMOS load transistors having drain/source regions with dopant concentrations of 1e17 atoms/cmor less. The dopant concentration of the drain/source regions of the PMOS load transistors is significantly lower than the dopant concentration of lightly doped drain/source regions in PMOS transistors used in peripheral circuitry.

SRAM system having very lightly doped SRAM load transistors for improving SRAM cell stability and method for making the same

A ternary CAM system includes a main memory cell configured to store complementary data signals D/D&num;. A first transistor has a source coupled to receive data signal D&num;, and a gate coupled to receive a compare signal C. A second transistor has a source coupled to receive data signal D, and a gate coupled to receive complementary compare signal C&num;. A third transistor has a gate coupled to drain regions of the first and second transistors. A mask cell storing a mask value is coupled to the source of the third transistor. A pre-charged match line is coupled to the drain of the third transistor. If compare signals C/C&num; match data signals D/D&num;, then the third transistor is turned off, thereby isolating match line and mask cell. If compare signals C/C&num; don't match data signals D/D&num;, then the third transistor is turned on, thereby coupling mask cell and match line.

Compact ternary content addressable memory cell

Growing community of inventors

Palo Alto, CA, United States of America

Jeong Yeol Choi