Contact Resistivity of Laser Annealed SiGe for MEMS Structural Layers Deposited at 210°C

2011 ◽  
Vol 1299 ◽  
Author(s):  
Joumana El-Rifai ◽  
Ann Witvrouw ◽  
Ahmed Abdel Aziz ◽  
Robert Puers ◽  
Chris Van Hoof ◽  
...  
Keyword(s):  
Silicon Germanium ◽  
Laser Annealing ◽  
Contact Resistivity ◽  
Silicon Substrates ◽  
Lower Electrode ◽  
Micro Electro Mechanical Systems ◽  
High Hydrogen ◽  
Flexible Polymer ◽  
Major Disadvantage ◽  
Structural Layer

ABSTRACTLowering the silicon germanium (SiGe) deposition temperature from the current 450°C to below 250°C will enable processing Micro Electro-Mechanical Systems (MEMS) on flexible polymer instead of on rigid silicon substrates or glass carriers. A major disadvantage of such a low temperature deposition is that the films are amorphous, with high hydrogen content and yield poor electrical and mechanical properties. To ensure films suitable for MEMS applications, a post-deposition laser annealing (LA) treatment is used. It is essential that the contact resistance between the SiGe MEMS structural layer and any lower electrode is minimized. In this work we investigate what beneficial effect a LA treatment can have on the contact resistivity of an initially amorphous SiGe MEMS structural layer with a bottom TiN electrode. We report a minimum contact resistivity of 2.14×10−3Ωcm2.

Low Thermal Budget Techniques For Controlling Stress In Si1-XGeX Deposited At 210°C

2006 ◽  
Vol 910 ◽  
Author(s):  
Sherif Sedky ◽  
Omar Mortagy ◽  
Ann Witvrouw
Keyword(s):  
Physical Properties ◽  
Strain Gradient ◽  
Silicon Germanium ◽  
Laser Annealing ◽  
Excimer Laser Annealing ◽  
High Hydrogen ◽  
High Laser ◽  
The Cost ◽  
Low Thermal Budget ◽  
First Time

AbstractThis work reports, for the first time, on the possibility of realizing surface micromachined silicon germanium structures at 210°C, which have extremely low strain gradient (μm-1). This extremely low strain gradient is obtained by tuning the physical properties of Si1-xGex, locally, without affecting the underlying layers, by excimer laser annealing. Tuning the laser annealing condition to optimize the physical properties of PECVD Si1-xGex is challenging, especially for films deposited at low temperatures (~ 250°C or lower) due to the high hydrogen content and the poor adhesion of these films. Furthermore, optimizing some properties might be at the cost of others. To clarify this issue, it is interesting to note that reducing the electrical resistivity implies using high laser pulse fluence. This however will increase mean stress, strain gradient and surface roughness as will be shown in this work.

A Novel Gap Narrowing Process for Creating High Aspect Ratio Transduction Gaps for MEM HF Resonators

2008 ◽  
Vol 1139 ◽  
Author(s):  
Steve Stoffels ◽  
George Bryce ◽  
Rita Van Hoof ◽  
Bert Du Bois ◽  
Robert Mertens ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Silicon Germanium ◽  
High Frequency ◽  
Air Gaps ◽  
Processing Step ◽  
Process Methodology ◽  
Thick Layers ◽  
Validation Experiments ◽  
Structural Layer

AbstractIn this work a novel technique to create nanometer sized air gaps for high frequency (HF) mechanical resonators will be presented. The technique is based on the narrowing of initially wide gaps with a conformal “narrowing” layer. The novelty of this technique is that it enables the creation of narrow high-aspect ratio gaps (e.g. 100nm gaps in 10μm thick layers) without the need for complex lithography or high aspect ratio etching. Furthermore, the electrodes and the resonator itself can be patterned in a single processing step. The process methodology will be explained and validation experiments in a silicon-germanium (SiGe) based technology will be shown. This technology uses low temperature (∼450°C) poly silicon-germanium (SiGe) as the structural layer, which can be processed above CMOS, and therefore allows the fabrication of MEM devices above CMOS.

Heterostructures of GaAs and AlAs on Silicon: X-Ray Analysis and Excimer Laser Annealing

1988 ◽  
Vol 116 ◽  
Author(s):  
A. Georgakilas ◽  
M. Fatemi ◽  
L. Fotiadis ◽  
A. Christou
Keyword(s):  
Molecular Beam Epitaxy ◽  
Dislocation Density ◽  
Excimer Laser ◽  
Molecular Beam ◽  
Laser Annealing ◽  
High Resistivity ◽  
Silicon Substrates ◽  
Excimer Laser Annealing ◽  
X Ray ◽  
High Resistivity Silicon

AbstractOne micron thick AlAs/GaAs structures have been deposited by molecular beam epitaxy onto high resistivity silicon substrates. Subsequent to deposition, it is shown that Excimer laser annealing up to 120mJ/cm2 at 248nm improves the GaAs mobility to approximately 2000cm2 /v-s. Dislocation density, however, did not decrease up to 180mJ/cm2 showing that improvement in transport properties may not be accompanied by an associated decrease in dislocation density at the GaAs/Si interface.

Development of Stable a-Si/a-SiGe Tandem Solar Cell Submodules Deposited by a Very High Hydrogen Dilution at Low Temperature

1998 ◽  
Vol 507 ◽  
Author(s):  
Masaki Shima ◽  
Masao Isomura ◽  
Eiji Maruyama ◽  
Shingo Okamoto ◽  
Hisao Haku ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Silicon Germanium ◽  
Structural Variations ◽  
High Hydrogen ◽  
Hydrogen Dilution ◽  
Hydrogen Radicals ◽  
Amorphous Silicon Germanium ◽  
Hydrogenated Amorphous ◽  
Very High

ABSTRACTThe world's highest stabilized efficiency of 9.5% (light-soaked and measured by the Japan Quality Assurance Organization (JQA)) for an a-Si/a-SiGe superstrate-type solar cell submodule (area: 1200 cm2) has been achieved. This value was obtained by investigating the effects of very-high hydrogen dilution of up to 54:1 (= H2: SiH4) on hydrogenated amorphous silicon germanium (a-SiGe:H) deposition at a low substrate temperature (Ts). It was found that deterioration of the film properties of a-SiGe:H when Ts decreases under low hydrogen dilution conditions can be suppressed by the high hydrogen dilution. This finding probably indicates that the energy provided by hydrogen radicals substitutes for the lost energy caused by the decrease in Ts and that sufficient surface reactions can occur. In addition, results from an estimation of the hydrogen and germanium contents of a-SiGe:H suggest the occurrence of some kinds of structural variations by the high hydrogen dilution. A guideline for optimization of a-SiGe:H films for solar cells can be presented on the basis of the experimental results. The possibility of a-SiGe:H as a narrow gap material for a-Si stacked solar cells in contrast with microcrystalline silicon (μ c-Si:H) will also be discussed from various standpoints. At present, a-SiGe:H is considered to have an advantage over μ1 c-Si:H.

Doping and crystallization of amorphous SiGe films with an excimer (KrF) laser

1995 ◽  
Vol 10 (8) ◽  
pp. 1884-1888 ◽  
Author(s):  
S. Krishnan ◽  
M.I. Chaudhry ◽  
S.V. Babu
Keyword(s):  
Silicon Germanium ◽  
Room Temperature ◽  
Laser Pulses ◽  
Laser Exposure ◽  
Silicon Substrates ◽  
A Value ◽  
Crystal Film ◽  
Krf Laser ◽  
Amorphous Silicon Germanium

Amorphous silicon germanium (a-SiGe) films, deposited on silicon substrates at room temperature in a molecular beam epitaxy system, were transformed into a single-crystal film and doped with phosphorus by exposure to KrF laser pulses. Electron channeling patterns showed that laser exposure resulted in crystallization of the undoped a-SiGe films. The SiGe films were doped by laser irradiation, using a phosphorus spin-on-dopant. The sheet resistance of the doped films decreased with increasing numbers of pulses, reaching a value of about ∼ 5 × 104 ohms/□ after 15 pulses. I-V data from mesa-type n-SiGe/p-Si diode devices were used to determine the effect of laser processing on the quality of the SiGe films.

High-speed amorphous silicon germanium infrared sensors prepared on crystalline silicon substrates

1998 ◽  
Vol 45 (9) ◽  
pp. 2085-2088 ◽  
Author(s):  
Jyh-Jier Ho ◽  
Y.K. Fang ◽  
Kun-Hsien Wu ◽  
W.T. Hsieh ◽  
S.C. Huang ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Silicon Germanium ◽  
High Speed ◽  
Crystalline Silicon ◽  
Silicon Substrates ◽  
Infrared Sensors ◽  
Amorphous Silicon Germanium

Thermodynamic and Kinetic Studies of Pulsed-Laser Annealing from Transient Conductivity Measurements

1984 ◽  
Vol 35 ◽  
Author(s):  
P.S. Peercy ◽  
Michael O. Thompson
Keyword(s):  
Melting Temperature ◽  
Silicon Germanium ◽  
Laser Annealing ◽  
Pulsed Laser ◽  
Kinetic Studies ◽  
Alloy System ◽  
Velocity Versus ◽  
Solidification Velocity ◽  
Molten Layer ◽  
Amorphous Si

ABSTRACTSimultaneous measurements of the transient conductance and time-dependent surface reflectance of the melt and solidification dynamics produced by pulsed laser irradiation of Si are reviewed. These measurements demonstrate that the melting temperature of amorphous Si is reduced 200 ± 50 K from that of crystalline Si and that explosive crystallization in amorphous Si is mediated by a thin (≤ 20 nm) molten layer that propagates at ~ 15 m/sec. Studies with 3.5 nsec pulses permit an estimate of the dependence of the solidification velocity on undercooling. Measurements of the effect of As impurities on the solidification velocity demonstrate that high As concentrations decrease the melting temperature of Si (~ 150 K for 7 at.%), which can result in surface nucleation to produce buried melts. Finally, the silicon-germanium alloy system is shown to be an ideal model system for the study of superheating and undercooling. The Si50Ge50 alloy closely models amorphous Si, and measurements of layered Si-Ge alloy structures indicate superheating up to 120 K without nucleation of internal melts. The change in melt velocity with superheating yields a velocity versus superheating of 17 ± 3 k/m/sec.

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