Advanced Micro Devices Corporation

Globalfoundries Inc.

Manfred Horstmann

Karsten Wieczorek

Rolf Stephan

Andy C Wei

Thorsten E Kammler

Thomas Feudel

Jan Hoentschel

Frederick N Hause

Joe Bloomquist

Sven Beyer

Peter Javorka

Christoph Schwan

Frank Wirbeleit

Patrick Press

Stephan Kruegel

Gert Burbach

Karla Romero

Kerstin Ruttloff

Michael Raab

Wolfgang Buchholtz

Markus Forsberg

Kai Frohberg

Martin Gerhardt

Christian Krueger

Christian Kr&uuml;ger

Ralf Richter

Markus Lenski

Roman Boschke

Joerg Hohage

Martin Trentzsch

Ralf Van Bentum

Andreas Gehring

Peter Huebler

Mark Craig

Bernd Engelmann

Tilo Mantei

Thomas Heller

Markus Forseberg

Christian Hobert

A method of forming a field effect transistor comprises providing a substrate comprising a biaxially strained layer of a semiconductor material. A gate electrode is formed on the biaxially strained layer of semiconductor material. A raised source region and a raised drain region are formed adjacent the gate electrode. Ions of a dopant material are implanted into the raised source region and the raised drain region to form an extended source region and an extended drain region. Moreover, in methods of forming a field effect transistor according to embodiments of the present invention, a gate electrode can be formed in a recess of a layer of semiconductor material. Thus, a field effect transistor wherein a source side channel contact region and a drain side channel contact region located adjacent a channel region are subject to biaxial strain can be obtained.

Method of forming a field effect transistor

By combining an anneal process for adjusting the effective channel length and a substantially diffusion-free anneal process performed after a deep drain and source implantation, the vertical extension of the drain and source region may be increased substantially without affecting the previously adjusted channel length. In this manner, in SOI devices, the drain and source regions may extend down to the buried insulating layer, thereby reducing the parasitic capacitance, while the degree of dopant activation and thus series resistance in the extension regions may be improved. Furthermore, less critical process parameters during the anneal process for adjusting the channel length may provide the potential for reducing the lateral dimensions of the transistor devices.

Enhancing transistor characteristics by a late deep implantation in combination with a diffusion-free anneal process

By recessing drain and source regions, a highly stressed layer, such as a contact etch stop layer, may be formed in the recess in order to enhance the strain generation in the adjacent channel region of a field effect transistor. Moreover, a strained semiconductor material may be positioned in close proximity to the channel region by reducing or avoiding undue relaxation effects of metal silicides, thereby also providing enhanced efficiency for the strain generation. In some aspects, both effects may be combined to obtain an even more efficient strain-inducing mechanism.

Technique for providing stress sources in transistors in close proximity to a channel region by recessing drain and source regions

In a memory cell, the drive current capabilities of the transistors may be adjusted by locally providing an increased gate dielectric thickness and/or gate length of one or more of the transistors of the memory cell. That is, the gate length and/or the gate dielectric thickness may vary along the transistor width direction, thereby providing an efficient mechanism for adjusting the effective drive current capability while at the same time allowing the usage of a simplified geometry of the active region, which may result in enhanced production yield due to enhanced process uniformity. In particular, the probability of creating short circuits caused by nickel silicide portions may be reduced.

Drive current adjustment for transistors by local gate engineering

By forming isolation trenches of different types of intrinsic stress on the basis of separate process sequences, the strain characteristics of adjacent active semiconductor regions may be adjusted so as to obtain overall device performance. For example, highly stressed dielectric fill material including compressive and tensile stress may be appropriately provided in the respective isolation trenches in order to correspondingly adapt the charge carrier mobility of respective channel regions.

Semiconductor device comprising isolation trenches inducing different types of strain

In a mesa isolation configuration for forming a transistor on a semiconductor island, an additional planarization step is performed to enhance the uniformity of the gate patterning process. In some illustrative embodiments, the gate electrode material may be planarized, for instance, on the basis of CMP, to compensate for the highly non-uniform surface topography, when the gate electrode material is formed above the non-filled isolation trenches. Consequently, significant advantages of the mesa isolation strategy may be combined with a high degree of scalability due to the enhancement of the critical gate patterning process.

Method of enhancing lithography capabilities during gate formation in semiconductors having a pronounced surface topography

In a dual stress liner approach, an intermediate etch stop material may be provided on the basis of a plasma-assisted oxidation process rather than by deposition so the corresponding thickness of the etch stop material may be reduced. Consequently, the resulting aspect ratio may be less pronounced compared to conventional strategies, thereby reducing deposition-related irregularities which may translate into a significant reduction of yield loss, in particular for highly scaled semiconductor devices.

Etch stop layer of reduced thickness for patterning a dielectric material in a contact level of closely spaced transistors

By incorporating nitrogen into the P-doped regions and N-doped regions of the gate electrode material prior to patterning the gate electrode structure, yield losses due to reactive wet chemical cleaning processes may be significantly reduced.

Method for reducing defects of gate of CMOS devices during cleaning processes by modifying a parasitic PN junction

By forming a substantially continuous and uniform semiconductor alloy in one active region while patterning the semiconductor alloy in a second active region so as to provide a base semiconductor material in a central portion thereof, different types of strain may be induced, while, after providing a corresponding cover layer of the base semiconductor material, well-established process techniques for forming the gate dielectric may be used. In some illustrative embodiments, a substantially self-aligned process is provided in which the gate electrode may be formed on the basis of layer, which has also been used for defining the central portion of the base semiconductor material of one of the active regions. Hence, by using a single semiconductor alloy, the performance of transistors of different conductivity types may be individually enhanced.

Semiconductor device comprising NMOS and PMOS transistors with embedded Si/Ge material for creating tensile and compressive strain

By embedding a silicon/germanium mixture in a silicon layer of high tensile strain, a moderately high degree of tensile strain may be maintained in the silicon/germanium mixture, thereby enabling increased performance of N-channel transistors on the basis of silicon/germanium material. In other regions, the germanium concentration may be varied to provide different levels of tensile or compressive strain.

Tensile strain source using silicon/germanium in globally strained silicon

By forming bulk-like transistors in sensitive RAM areas of otherwise SOI-based CMOS circuits, a significant savings in valuable chip area may be achieved since the RAM areas may be formed on the basis of a bulk transistor configuration, thereby eliminating hysteresis effects that may typically be taken into consideration by providing transistors of increased transistor width or by providing body ties. Hence, the benefit of high switching speed may be maintained in speed-critical circuitry, such as CPU cores, while at the same time the RAM circuit may be formed in a highly space-efficient manner.

Method for manufacturing semiconductor device comprising SOI transistors and bulk transistors

By forming a stressed dielectric layer on different transistors and subsequently relaxing a portion thereof, the overall process efficiency in an approach for creating strain in channel regions of transistors by stressed overlayers may be enhanced while nevertheless transistor performance gain may be obtained for each type of transistor, since a highly stressed material positioned above the previously relaxed portion may also efficiently affect the underlying transistor.

Stress transfer in an interlayer dielectric by providing a stressed dielectric layer above a stress-neutral dielectric material in a semiconductor device

By introducing a atomic species, such as carbon, fluorine and the like, into the drain and source regions, as well as in the body region, the junction leakage of SOI transistors may be significantly increased, thereby providing an enhanced leakage path for accumulated minority charge carriers. Consequently, fluctuations of the body potential may be significantly reduced, thereby improving the overall performance of advanced SOI devices. In particular embodiments, the mechanism may be selectively applied to threshold voltage sensitive device areas, such as static RAM areas.

SOI transistor having a reduced body potential and a method of forming the same

By forming a portion of a PN junction within strained silicon/germanium material in SOI transistors with a floating body architecture, the junction leakage may be significantly increased, thereby reducing floating body effects. The positioning of a portion of the PN junction within the strained silicon/germanium material may be accomplished on the basis of implantation and anneal techniques, contrary to conventional approaches in which in situ doped silicon/germanium is epitaxially grown so as to form the deep drain and source regions. Consequently, high drive current capability may be combined with a reduction of floating body effects.

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Duerrroehrsdorf-Dittersbach, Germany

Manfred Horstmann