At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

American Telephone and Telegraph, Co.

Kwing F Lee

Ran-Hong Yan

Tzu-Yin Chiu

Gen M Chin

Maureen Y Lau

Mark D Morris

Ronald C Hanson

William T Lynch

Avinoam Kornblit

Alexander M Voshchenkov

Joseph Lebowitz

Abbas Ourmazd

Alexander M Voschenkov

A method for manufacturing an MOS device, such as a PMOS transistor, on a silicon wafer. The method includes steps leading to the formation of a polysilicon gate electrode, and at least one ion-implantation step for forming source and drain junction regions in the silicon wafer. The method further comprises, before the ion-implantation step, the step of forming a first sidewall contactingly disposed adjacent the polysilicon gate electrode. The ion-implantation step is then performed such that the resulting source and drain junction regions are at least partially excluded from that portion of the silicon wafer that directly underlies the polysilicon gate electrode and the sidewall. In preferred embodiments of the invention, a first ion-implantation step is performed after the first sidewall is formed, then a second sidewall is formed adjacent and contiguous with the first sidewall, and then a second ion-implantation step is performed, resulting in the formation of further source and drain junction regions which are at least partially excluded from that portion of the silicon wafer that directly underlies the polysilicon gate electrode and the first and second sidewalls.

Method for making a MOS device

A silicon MOSFET is provided, which can be made with an effective channel length of under one micrometer without incurring severe short-channel effects. The MOSFET includes first and second channel regions located between the source and drain regions, the first channel region overlaying the second channel region. The second channel region has a higher carrier density than the first channel region, and functions as a buried ground plane.

Insulated gate field-effect transistor with pulse-shaped doping

A process for creating bipolar and CMOS transistors on a p-type silicon substrate is disclosed. The silicon substrate has typical n+ buried wells and field oxide regions to isolate the individual transistor devices. In accordance with the process, stacks of material are created over the gate elements of the CMOS devices and over the emitter elements of the bipolar transistors. The stacks of material over the gate elements have a silicon dioxide gate layer in contact with the epitaxial layer of the substrate, and the stacks of material over the emitter elements have a polycrystalline silicon layer in contact with the epitaxial layer. Walls of silicon dioxide are created around the stacks in order to insulate the material within the stacks from the material deposited outside of the walls. Polycrystalline silicon in contact with the epitaxial layer is deposited outside the walls surrounding the stacks. All polycrystalline silicon layers in contact with the epitaxial layer are implanted with appropriate dopants such that these layers serve as reservoirs of dopant in order to simultaneously create the source and drain elements of the CMOS devices and the emitter elements of the bipolar devices during a heating step in the process. A tungsten layer is deposited over the polycrystalline layer in order to provide a conductive coupling to aluminum electrodes.

Process for manufacturing semiconductor BICMOS device

A process for creating bipolar and CMOS transistors on a p-type silicon substrate is disclosed. The silicon substrate has a typical n+ buried wells and field oxide regions to isolate the individual transistor devices. In accordance with the process, stacks of material are created over the gate elements of the CMOS devices and over the emitter elements of the bipolar transistors. The stacks of material over the gate elements have a silicon dioxide gate layer in contact with the epitaxial layer of the substrate, and the stacks of material over the emitter elements have a polycrystalline silicon layer in contact with the epitaxial layer. Walls of silicon dioxide are created around the stacks in order to insulate the material within the stacks from the material deposited outside of the walls. Polycrystalline silicon in contact with the epitaxial layer is deposited outside the walls surrounding the stacks. All polycrystalline silicon layers in contact with the epitaxial layer are implanted with appropriate dopants such that these layers serve as reservoirs of dopant in order to simultaneously create the source and drain elements of the CMOS devices and the emitter elements of the bipolar device during a heating step in the process. A tungsten layer is deposited over the polycrystalline layer in order to provide a conductive coupling to aluminum electrodes.

Growing community of inventors

Aberdeen, NJ, United States of America

Kwing F Lee