Motorola Corporation

Standard Microsystems Corporation

Patrick J Holly

Louis C Parrillo

Frank K Baker

Richard W Mauntel

Stephen J Cosentino

David R Rodriguez

David R Rice

A system, e.g. an integrated circuit or part, may include a plurality of pads, e.g. digital I/O pads, each comprising a physical pad and associated pad circuit. In case of an ESD event affecting one or more of the digital I/O pads, PMOS devices configured in an output buffer section between an I/O pad supply rail and the physical output pad&#x2014;within their respective pad circuits in the affected digital I/O pads&#x2014;may all be turned on in response to the ESD event. This may allow the capacitance of each pad, in some cases approximately 3 pF capacitance per pad, to charge up, absorbing the energy of the ESD event and reducing the peak voltage the integrated circuit or part experiences as a result of the ESD event. The reduced peak voltage may be directly correlated with improved ESD performance of the product.

Pad ESD spreading technique

A process of forming a conductive material layer in at least two steps by forming a conductive material layer from a plurality of thin layers of conductive material. The use of a two-step formation process for the conductive material layer permits process versatility in incorporating implantation steps and patterning steps between formation of the thin layers of conductive material. Direct transfer from dielectric layer formation to conductive material layer formation steps, and performing the intermediate process steps in the same piece of equipment as the thin conductive layer formation assists in adhesion of the thin layers to each other to form the total conductive material layer. The use of in situ doped semiconductor material, such as in situ doped polycrystalline silicon and in situ doped amorphous silicon reduces the exposure of other dopants that may be present to thermal cycles of high temperature, greater than 900.degree. C., that causes these dopants to migrate undesirably.

Multiple step formation of conductive material layers

A process for forming graded source/drain regions in semiconductor devices involves two ion implantation steps and an optional drive-in step. The first implantation is a low dose implant with high energy and/or low mass ions to form the deeper grading region. The second implant is a high does implant with low energy and/or high mass ions to form the shallower, lower resistivity source/drain region. Without the optional drive-in step, virtually no lateral grading takes place, resulting in little encroachment of the grading region under the gate. The use of a drive-in step between the two implant steps causes diffusion of the grading dopant, which increases the grading both laterally and vertically, resulting in better breakdown and capacitance characteristics, but increased encroachment under the gate. The present invention allows control over the lateral and vertical grading separately to optimize the trade-offs for a particular application.

Double-implant process for forming graded source/drain regions

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Tempe, AZ, United States of America

Patrick J Holly