United Microelectronics Corp.

Tsun-Tsai Chang

Chen-Chung Hsu

Ming-Tsung Liu

Larry Lin

Vicent Liu

The invention provides a photodiode structure having a first conductive type substrate and at least an isolation region, the photodiode structure comprising a doped second conductive type region, wherein the doped second conductive type region is formed in the substrate at a distance from the neighboring isolation region, and a mask layer covering at least a peripheral strip near the edge of the isolation region so that the doped second conductive type region is exposed.

Photodiode structure having mask to reduce leakage current

A buried contact structure is provided for forming a contact between a source/drain region of a MOSFET and polysilicon conducting line. The polysilicon conducting line is formed on a field oxide region and extends onto the surface of the semiconductor substrate near the source/drain region. A polysilicon sidewall structure is formed in contact with the vertical edge of the polysilicon conducting line and the horizontal surface of the source/drain region to provide contact between the polysilicon conducting line and the source/drain region.

Buried contact structure

A process for fabricating a protective shield for polysilicon loads in SRAM devices is disclosed. The protective shield enables to protect the polyloads from resistance characteristics degradation during the subsequent plasma-based processing steps in the fabrication of the memory device after the polyloads are formed. The polyloads are formed in a photolithography procedure by utilizing a photomask defining the resistive and conductive portions of the polyloads. The process comprises the steps of forming a shield silicon oxide layer over the surface of the memory device in process, including the polyloads, and forming a shield silicon nitride layer on the top of the shield silicon oxide layer. The protective shield is then formed by etching in the shield silicon oxide and nitride layers utilizing a protective photomask. The protective photomask is the same photomask utilized in the formation of the polyloads in the previous photolithography procedural step of the fabrication of the memory device.

Process for fabricating shield for polysilicon load

A shield structure is formed over each of the undoped or lightly doped polysilicon load devices of a 4T SRAM cell. The shield structure may be a metal such as aluminum, titanium or tungsten and serves to protect the undoped or lightly doped resistor within a polysilicon load device from charge-induced damage during ion implantation or plasma processing steps performed on the SRAM after formation of the polysilicon load device. The polysilicon load device is defined by depositing a layer of photoresist, exposing the photoresist through a master load mask, etching, and implanting into the exposed polysilicon. After the load device is formed, a dielectric layer is deposited and then a layer of conductive material is deposited. Dummy conductor structures are formed from the layer of conductive material using photolithography and the master load mask.

Method of manufacturing an SRAM load shield

A buried contact structure formed on a semiconductor substrate. A single polysilicon layer is formed on a field oxide layer. The polysilicon layer is patterned and etched to form an interconnect layer. A silicide layer is formed on the sidewall of the interconnect layer. The silicide layer connects a buried contact region with the interconnect layer to make electrical contact between the interconnect layer and a source/drain region.

Method of fabricating a buried contact structure for SRAM

A process for coding and code marking a read-only memory device makes use of a buffer layer, such as silicon nitrides (Si.sub.3 N.sub.4) or silicon oxynitrides (SiN.sub.x O.sub.y), to form a code mark therein. Owing to the etching selectivity between the buffer layer and an underlying layer, for example, silicon oxides, the programmed region not covered by the word lines will not suffer from etching damage while forming the code mark. Therefore, the coding and code marking process can employ the same mask layer, but without the need for two different photomasking procedures to implement code programming and identification code marking.

Growing community of inventors

Hsinchu, Taiwan

Tsun-Tsai Chang