Globalfoundries Inc.

Advanced Micro Devices Corporation

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Stephan Kronholz

Vassilios Papageorgiou

Peter Javorka

Markus Lenski

Stephan-Detlef Kronholz

Carsten Reichel

Jan Hoentschel

Thorsten E Kammler

Rohit Pal

Frank Seliger

Frank Richter

Andreas Naumann

A semiconductor device includes drain and source regions positioned in an active region of a transistor and a channel region positioned laterally between the drain and source regions that includes a semiconductor base material and a threshold voltage adjusting semiconductor material positioned on the semiconductor base material. A gate electrode structure is positioned on the threshold voltage adjusting semiconductor material, and a strain-inducing semiconductor alloy including a first semiconductor material and a second semiconductor material positioned above the first semiconductor material is embedded in the semiconductor base material of the active region. A crystalline buffer layer of a third semiconductor material surrounds the embedded strain-inducing semiconductor alloy, wherein an upper portion of the crystalline buffer layer laterally confines the channel region including the sidewalls of the threshold voltage adjusting semiconductor material and is positioned between the second semiconductor material and the threshold voltage adjusting semiconductor material.

Performance enhancement in transistors by providing an embedded strain-inducing semiconductor material on the basis of a seed layer

In sophisticated semiconductor devices, transistors may be formed on the basis of a high-k metal gate electrode structure provided in an early manufacturing phase, wherein an efficient strain-inducing mechanism may be implemented by using an embedded strain-inducing semiconductor alloy. In order to reduce the number of lattice defects and provide enhanced etch resistivity in a critical zone, i.e., in a zone in which a threshold voltage adjusting semiconductor alloy and the strain-inducing semiconductor material are positioned in close proximity, an efficient buffer material or seed material, such as a silicon material, is incorporated, which may be accomplished during the selective epitaxial growth process.

When forming sophisticated semiconductor devices including complementary transistors having a reduced gate length, the individual transistor characteristics may be adjusted on the basis of individually provided semiconductor alloys, such as a silicon/germanium alloy for P-channel transistors and a silicon/phosphorous semiconductor alloy for N-channel transistors. To this end, a superior hard mask patterning regime may be applied in order to provide compatibility with sophisticated replacement gate approaches, while avoiding undue process non-uniformities, in particular with respect to the removal of a dielectric cap layer.

Complementary transistors comprising high-k metal gate electrode structures and epitaxially formed semiconductor materials in the drain and source areas

When forming sophisticated gate electrode structures, such as high-k metal gate electrode structures, an appropriate encapsulation may be achieved, while also undue material loss of a strain-inducing semiconductor material that is provided in one type of transistor may be avoided. To this end, the patterning of the protective spacer structure prior to depositing the strain-inducing semiconductor material may be achieved for each type of transistor on the basis of the same process flow, while, after the deposition of the strain-inducing semiconductor material, an etch stop layer may be provided so as to preserve integrity of the active regions.

Sophisticated gate electrode structures formed by cap layer removal with reduced loss of embedded strain-inducing semiconductor material

When forming sophisticated semiconductor devices including transistors with sophisticated high-k metal gate electrode structures and a strain-inducing semiconductor alloy, transistor uniformity and performance may be enhanced by providing superior growth conditions during the selective epitaxial growth process. To this end, a semiconductor material may be preserved at the isolation regions in order to avoid the formation of pronounced shoulders. Furthermore, in some illustrative embodiments, additional mechanisms are implemented in order to avoid undue material loss, for instance upon removing a dielectric cap material and the like.

Transistors with embedded strain-inducing material formed in cavities provided by an oxidizing etch process

When forming sophisticated high-k metal gate electrode structures, a threshold adjusting semiconductor alloy may be formed on the basis of selective epitaxial growth techniques and a hard mask comprising at least two hard mask layers. The hard mask may be patterned on the basis of a plasma-based etch process, thereby providing superior uniformity during the further processing upon depositing the threshold adjusting semiconductor material. In some illustrative embodiments, one hard mask layer is removed prior to actually selectively depositing the threshold adjusting semiconductor material.

Formation of a channel semiconductor alloy by forming a hard mask layer stack and applying a plasma-based mask patterning process

The threshold voltage of a sophisticated transistor may be adjusted by providing a specifically designed semiconductor alloy in the channel region of the transistor, wherein a negative effect of this semiconductor material with respect to inducing a strain component in the channel region may be reduced or over-compensated for by additionally incorporating a strain-adjusting species. For example, a carbon species may be incorporated in the channel region, the threshold voltage of which may be adjusted on the basis of a silicon/germanium alloy of a P-channel transistor. Consequently, sophisticated metal gate electrodes may be formed in an early manufacturing stage.

Adjusting of strain caused in a transistor channel by semiconductor material provided for threshold adjustment

In a transistor, a strain-inducing semiconductor alloy, such as silicon/germanium, silicon/carbon and the like, may be positioned very close to the channel region by providing gradually shaped cavities which may then be filled with the strain-inducing semiconductor alloy. For this purpose, two or more 'disposable' spacer elements of different etch behavior may be used in order to define different lateral offsets at different depths of the corresponding cavities. Consequently, enhanced uniformity and, thus, reduced transistor variability may be accomplished, even for sophisticated semiconductor devices.

Transistor with an embedded strain-inducing material having a gradually shaped configuration

The growth rate in a selective epitaxial growth process for depositing a threshold adjusting semiconductor alloy, such as a silicon/germanium alloy, may be enhanced by performing a plasma-assisted etch process prior to performing the selective epitaxial growth process. For example, a mask layer may be patterned on the basis of the plasma-assisted etch process, thereby simultaneously providing superior device topography during the subsequent growth process. Hence, the threshold adjusting material may be deposited with enhanced thickness uniformity, thereby reducing overall threshold variability.

Reduction of thickness variations of a threshold semiconductor alloy by reducing patterning non-uniformities prior to depositing the semiconductor alloy

In sophisticated semiconductor devices, an asymmetric transistor configuration may be obtained on the basis of a strain-inducing semiconductor alloy. To this end, strain relaxation implantation processes may be performed at the drain side according to some illustrative embodiments, while, in other cases, the deposition of the strain-inducing alloy may be performed in an asymmetric manner with respect to the drain side and the source side of the transistor.

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Dresden, Germany

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