International Business Machines Corporation

Deborah A Tucker

Steven M Shank

James Spiros Nakos

Dale Warner Martin

Jay Sanford Burnham

James J Quinlivan

Beth A Ward

Michael C Triplett

Wing clipper quilt template

Quilt trimmer template

A gate stack structure. The structure includes (a) a semiconductor region and (b) a gate stack on top of the semiconductor region. The gate stack includes (i) a gate dielectric region on top of the semiconductor region, (ii) a first gate polysilicon region on top of the gate dielectric region, and (iii) a second gate polysilicon region on top of the first gate polysilicon region and doped with a type of dopants. The structure further includes (c) a diffusion barrier region and a spacer oxide region on a side wall of the gate stack. The diffusion barrier region (i) is sandwiched between the gate stack and the spacer oxide region and (ii) is in direct physical contact with both the first and second gate polysilicon regions, and (iii) comprises a material having a property of preventing a diffusion of oxygen-containing materials through the diffusion barrier region.

Gate stacks

Quilt template

A structure and fabrication method for a gate stack used to define source/drain regions in a semiconductor substrate. The method comprises (a) forming a gate dielectric layer on top of the substrate, (b) forming a gate polysilicon layer on top of the gate dielectric layer, (c) implanting n-type dopants in a top layer of the gate polysilicon layer, (d) etching away portions of the gate polysilicon layer and the gate dielectric layer so as to form a gate stack on the substrate, and (e) thermally oxidizing side walls of the gate stack with the presence of a nitrogen-carrying gas. As a result, a diffusion barrier layer is formed at the same depth in the polysilicon material of the gate stack regardless of the doping concentration. Therefore, the n-type doped region of the gate stack has the same width as that of the undoped region of the gate stack.

Methods such as Remote Plasma Nitridation (RPN) are used to introduce nitrogen into a gate dielectric layer. However, these methods yield nitrided layers where the layers are not uniform, both in cross-sectional profile and in nitrogen profile. Subjecting the nitrided layer to an additional NO anneal process increases the uniformity of the nitrided layer.

Thermal nitrogen distribution method to improve uniformity of highly doped ultra-thin gate capacitors

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Westford, VT, United States of America

Deborah A Tucker