Integrated Device Technology, Inc.

Chung-Chyung Han

Jeong Yeol Choi

Chuen-Der Lien

Chung-Jen Chien

Ken-Chuen Mui

Cheun-Der Lien

A CMOS Structure is disclosed wherein two adjacent transistors of opposite conductivity each have a gate above their respective channel regions. Spacers are absent from the gate of one of the transistors. The structure is also characterized by lightly doped regions.

CMOS structure having a gate without spacers

A semiconductor substrate having a surface, a field oxide region at the surface and a gate structure above the surface are provided. A sidewall spacer is formed adjacent to the gate structure and a polysilicon layer is formed above the substrate, the polysilicon layer having raised first and second portions above the gate structure and field oxide region, respectively. A masking layer is formed above the polysilicon layer and then blanket etched to expose the raised first and second portions of the polysilicon layer which are subsequently removed to form a raised source/drain region from the polysilicon layer. Since the raised source/drain region is fabricated without using photolithography, high density MOSFETs are readily fabricated.

Mosfet with raised source and drain regions

A semiconductor substrate having a surface, a planarized field oxide region at the surface and a gate structure overlying the surface are provided. A sidewall spacer is formed adjacent to the gate structure and a polysilicon layer is formed overlying the substrate, the polysilicon layer having a raised first portion overlying the gate structure. A masking layer is formed overlying the polysilicon layer and then blanket etched to expose the raised first portion of the polysilicon layer which is subsequently removed. Since the raised first portion of the polysilicon layer is removed without using photolithography, high density MOSFETs are readily fabricated.

High density MOSFET with raised source and drain regions

A method of improving latch-up immunity and interwell isolation in a semiconductor device is provided. In one embodiment, an implant mask which has a variable permeability to implanted impurities is formed on the surface of a substrate having a first dopant region. A first portion of the implant mask overlies a first portion of the first dopant region. The structure is subjected to high energy implantation which forms a heavily doped region. A first portion of the heavily doped region is located along the lower boundary of the first dopant region. A second portion of the heavily doped region which extends along a side boundary of the first dopant region is formed by impurity ions which pass through the first portion of the implant mask. The heavily doped region improves latch-up immunity and interwell isolation without degrading threshold voltage tolerance. In alternative embodiments, one variable permeability mask is used to form the first dopant region and also to form the heavily doped region continuous with the first dopant region.

Method for improving latch-up immunity and interwell isolation in a

A structure for improving latch-up immunity and interwell isolation in a semiconductor device is provided. In one embodiment, a substrate has an upper surface and a first dopant region formed therein. The first dopant region has a lower boundary located below an upper surface of the substrate and a side boundary extending from the upper surface of the substrate to the lower boundary of the first dopant region. A heavily doped region having a first portion and a second portion located along the lower boundary and the side boundary of the first dopant region, respectively, has a substantially uniform dopant concentration greater than a dopant concentration of the first dopant region. The heavily doped region improves latch-up immunity and interwell isolation without degrading threshold voltage tolerance.

Structure for improving latch-up immunity and interwell isolation in a

A process for fabricating a CMOS structure using a single masking step to define lightly-doped source and drain regions for both N- and P-channel devices. The process forms disposable spacers adjacent to gate structures and at least one retrograde well. Retrograde wells are formed using one or more charged ions at different energy levels. In addition, heavily-doped source and drain regions are formed using blanket implants of two different conductivities into a semiconductor substrate having two contiguous wells of opposite conductivity type. By blanket implanting a first dopant into both wells, and then selectively implanting a second dopant, the diffusion of the second dopant is partially suppressed by the first dopant. The partial suppression of first dopant results in shallow implants being formed. Also disclosed is a process for forming contact openings and contact implants.

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San Jose, CA, United States of America

Chung-Chyung Han