Globalfoundries Inc.

Nadja Zakowsky

Stephan Kronholz

Markus Lenski

Yew Tuck Chow

A method for forming field effect transistors (FETs) in a multiple wafers per batch epi-reactor includes, providing substrates having therein at least one semiconductor (SC) region with a substantially flat outer surface, modifying such substantially flat outer surface to form a convex-outward curved surface, forming an epitaxial semiconductor layer on the curved surface, and incorporating the epitaxial layer in a field effect transistor formed on the substrate. Where the SC region is of silicon, the epitaxial layer can include silicon-germanium. In a preferred embodiment, the epi-layer forms part of the FET channel. Because of the convex-outward curved surface, the epi-layer grown thereon has much more uniform thickness even when formed in a high volume reactor holding as many as 100 or more substrates per batch. FETs with much more uniform properties are obtained, thereby greatly increasing the manufacturing yield and reducing the cost.

Epitaxial channel formation methods and structures

When forming sophisticated transistors on the basis of a high-k metal gate electrode structure and a strain-inducing semiconductor alloy, a superior wet cleaning process strategy is applied after forming cavities in order to reduce undue modification of sensitive gate materials, such as high-k dielectric materials, metal-containing electrode materials and the like, and modification of a threshold voltage adjusting semiconductor alloy. Thus, the pronounced dependence of the threshold voltage of transistors of different width may be significantly reduced compared to conventional strategies.

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Radeburg, Germany

Nadja Zakowsky