MOSFET device with localized stressor

Abstract

MOSFETs having localized stressors are provided. The MOSFET has a stress-inducing layer formed in the source / drain regions, wherein the stress-inducing layer comprises a first semiconductor material and a second semiconductor material. A treatment is performed on the stress-inducing layer such that a reaction is caused with the first semiconductor material and the second semiconductor material is forced lower into the stress-inducing layer. The stress-inducing layer may be either a recessed region or non-recessed region. A first method involves forming a stress-inducing layer, such as SiGe, in the source / drain regions and performing a nitridation or oxidation process. A nitride or oxide film is formed in the top portion of the stress-inducing layer, forcing the Ge lower into the stress-inducing layer. Another method embodiment involves forming a reaction layer over the stress-inducing layer and performing a treatment process to cause the reaction layer to react with the stress-inducing layer.

Description

TECHNICAL FIELD [0001] The present invention relates generally to semiconductor devices, and more particularly, to metal-oxide-semiconductor field-effect transistors and methods of manufacture. BACKGROUND [0002] Size reduction of metal-oxide-semiconductor field-effect transistors (MOSFET), including reduction of the gate length and gate oxide thickness, has enabled the continued improvement in speed, performance, density, and cost per unit function of integrated circuits over the past few decades. To further enhance transistor performance, MOSFET devices have been fabricated using strained channel regions located in portions of a semiconductor substrate. Strained channel regions allow enhanced carrier mobility to be realized, thereby resulting in increased performance when used for n-channel (NMOSFET) or for p-channel (PMOSFET) devices. Generally, it is desirable to induce a tensile strain in the n-channel of an NMOSFET transistor in the source-to-drain direction to increase electro...

AI Technical Summary

Benefits of technology

[0007] These and other problems are generally reduced, solved or circumvented, and technical advantages are generally achieved, by embodiments of the present invention, which provides a strained semiconductor device to improve the operating characteristics of the semiconductor device and a method of manufacture.

Problems solved by technology

This approach, however, can be difficult to process in addition to presenting junction leakage concerns as a result of the blanket semiconductor alloy layer.

The level of germanium in the epitaxially grown semiconductor alloy layer can be difficult to control.

In addition, the presence of a blanket semiconductor alloy layer allows an unwanted interface between the source / drain regions to exist, possibly introducing junction leakage

To increase the Ge concentration in the recessed area, however, creates process challenges.

For example, increasing the Ge concentration during the epitaxial growth results in a higher density of dislocations and defects in the SiGe layer.

Degraded selectivity and deposition process windows are also of concern.

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