HOME

TheInfoList



OR:

Strained silicon is a layer of
silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...
in which the silicon
atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished fr ...
s are stretched beyond their normal interatomic distance. This can be accomplished by putting the layer of silicon over a
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...
of silicon–germanium (). As the atoms in the silicon layer align with the atoms of the underlying silicon germanium layer (which are arranged a little further apart, with respect to those of a bulk silicon crystal), the links between the silicon atoms become stretched, thereby leading to strained silicon. Moving these silicon atoms further apart reduces the atomic forces that interfere with the movement of electrons through the transistors and thus improved
mobility Mobility may refer to: Social sciences and humanities * Economic mobility, ability of individuals or families to improve their economic status * Geographic mobility, the measure of how populations and goods move over time * Mobilities, a conte ...
, resulting in better chip performance and lower energy consumption. These
electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...
s can move 70% faster allowing strained silicon
transistor A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semicondu ...
s to switch 35% faster. More recent advances include deposition of strained silicon using
metalorganic Metal-organic compounds (jargon: metalorganics, metallo-organics) are a class of chemical compounds that contain metals and organic ligands, but lacking direct metal-carbon bonds. Metal β-diketonates, metal alkoxides, metal dialkylamides, transi ...
vapor-phase epitaxy (
MOVPE Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD), is a chemical vapour deposition method used to produce single- or polycrystalline thin films. ...
) with metalorganics as starting sources, e.g. silicon sources (
silane Silane (Silicane) is an inorganic compound with chemical formula . It is a colorless, pyrophoric gas with a sharp, repulsive, pungent smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental ...
and dichlorosilane) and germanium sources ( germane,
germanium tetrachloride Germanium tetrachloride is a colourless, fuming liquid with a peculiar, acidic odour. It is used as an intermediate in the production of purified germanium metal. In recent years, GeCl4 usage has increased substantially due to its use as a reagent ...
, and
isobutylgermane Isobutylgermane (IBGe, Chemical formula: (CH3)2CHCH2GeH3, is an organogermanium compound. It is a colourless, volatile liquid that is used in MOVPE (Metalorganic Vapor Phase Epitaxy) as an alternative to germane. IBGe is used in the deposition ...
). More recent methods of inducing strain include doping the source and drain with lattice mismatched atoms such as
germanium Germanium is a chemical element; it has Symbol (chemistry), symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid or a nonmetal in the carbon group that is chemically ...
and
carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...
.
Germanium Germanium is a chemical element; it has Symbol (chemistry), symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid or a nonmetal in the carbon group that is chemically ...
doping of up to 20% in the P-channel
MOSFET upright=1.3, Two power MOSFETs in amperes">A in the ''on'' state, dissipating up to about 100 watt">W and controlling a load of over 2000 W. A matchstick is pictured for scale. In electronics, the metal–oxide–semiconductor field- ...
source and drain causes uniaxial compressive strain in the channel, increasing hole mobility.
Carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...
doping as low as 0.25% in the N-channel MOSFET source and drain causes uniaxial tensile strain in the channel, increasing
electron mobility In solid-state physics, the electron mobility characterizes how quickly an electron can move through a metal or semiconductor when pushed or pulled by an electric field. There is an analogous quantity for Electron hole, holes, called hole mobilit ...
. Covering the NMOS transistor with a highly stressed
silicon nitride Silicon nitride is a chemical compound of the elements silicon and nitrogen. (''Trisilicon tetranitride'') is the most thermodynamically stable and commercially important of the silicon nitrides, and the term ″''Silicon nitride''″ commonly re ...
layer is another way to create uniaxial tensile strain. As opposed to wafer-level methods of inducing strain on the channel layer prior to MOSFET fabrication, the aforementioned methods use strain induced during the MOSFET fabrication itself to alter the carrier mobility in the transistor channel.


History

The idea of using germanium to strain silicon for the purpose of improving field-effect transistors appears to go back at least as far as 1991. In 2000, an MIT report investigated theoretical and experimental hole mobility in SiGe heterostructure-based PMOS devices. In 2003,
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
was reported to be among primary proponents of the technology. In 2002,
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer compo ...
had featured strained silicon technology in its 90nm
x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...
Pentium Pentium is a series of x86 architecture-compatible microprocessors produced by Intel from 1993 to 2023. The Pentium (original), original Pentium was Intel's fifth generation processor, succeeding the i486; Pentium was Intel's flagship proce ...
microprocessors series in early 2000. In 2005,
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer compo ...
was sued by AmberWave company for alleged patent infringement related to strained silicon technology.


See also

*
Strain engineering Strain engineering refers to a general strategy employed in semiconductor manufacturing to enhance device performance. Performance benefits are achieved by modulating strain, as one example, in the transistor channel, which enhances electron mobil ...
*
Hall effect The Hall effect is the production of a voltage, potential difference (the Hall voltage) across an electrical conductor that is wikt:transverse, transverse to an electric current in the conductor and to an applied magnetic field wikt:perpendicul ...
* Piezo effect


References


Further reading


Development of New Germanium Precursors for SiGe Epitaxy
Presentation at 210th ECS Meeting (SiGe Symposium), Cancun, Mexico, October 29, 2006. * {{cite journal, doi=10.1016/j.jcrysgro.2006.10.194 , title=Safer alternative liquid germanium precursors for relaxed graded SiGe layers and strained silicon by MOVPE , date=2007 , last1=Shenai , first1=Deo V. , last2=Dicarlo , first2=Ronald L. , last3=Power , first3=Michael B. , last4=Amamchyan , first4=Artashes , last5=Goyette , first5=Randall J. , last6=Woelk , first6=Egbert , journal=Journal of Crystal Growth , volume=298 , pages=172–175 , bibcode=2007JCrGr.298..172S Germanium Silicon, Strained Semiconductor material types Silicon