Fracture Behavior of Single- and Polycrystalline Silicon Films for MEMS Applications

2005 ◽  
Vol 297-300 ◽  
pp. 551-556 ◽  
Author(s):  
Dong Il Son ◽  
Jong Jin Kim ◽  
Dong Il Kwon
Keyword(s):  
Fracture Toughness ◽  
Resonance Frequency ◽  
Fracture Strength ◽  
Polycrystalline Silicon ◽  
Electrostatic Force ◽  
Silicon Film ◽  
Silicon Films ◽  
Microtensile Testing ◽  
The Mean ◽  
Doping Condition

Fracture behaviors of silicon films were evaluated by microtensile methods. We fabricated two types of specimens using surface micromachining, one for a test device for microtensile testing only and the other for a microtensile-compatible resonating device driven by alternating electrostatic force. The piezoelectric-driven uniaxial stress-strain measurement system was designed to evaluate the mechanical properties of thin films. We used UV adhesive to grip the device to the microtensile system, and the grip was made of UV-transparent glass in order to cure the underlying UV adhesive layer. To assess fracture toughness, we used newly proposed methods combining resonance frequency and microtensile methods. The fracture strength of single- and polycrystalline silicon showed dependence on geometry and doping condition. By varying the geometry, we analyzed the effect of the CMP side and the dry-etched side on changes in the mean fracture strength. Atomic force microscopy observation showed that the larger flaws of the dry-etched side were significant in decreasing the mean fracture strength. Fracture toughness based on fracture mechanics with a precrack was evaluated by newly proposed methods combining resonance frequency and microtensile techniques. The measured toughness was independent of specimen geometry but dependent on doping condition. The measured fracture toughness of notched specimens was 33% higher than that of pre-cracked specimens, even though the notch radius was as small as 1.4µm. The effects of notch-tip radius and doping on fracture toughness of silicon film were also analyzed.

Mechanical Properties of Transparent Polycrystalline Silicon Nitride

2006 ◽  
Vol 317-318 ◽  
pp. 305-308 ◽  
Author(s):  
Rak Joo Sung ◽  
Takafumi Kusunose ◽  
Tadachika Nakayama ◽  
Yoon Ho Kim ◽  
Tohru Sekino ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Young’S Modulus ◽  
Fracture Strength ◽  
Polycrystalline Silicon ◽  
Volume Fraction ◽  
Young's Modulus ◽  
Β Phase ◽  
Α Phase

A novel transparent polycrystalline silicon nitride was fabricated by hot-press sintering with MgO and AlN as additives. The mixed powder with 3 wt.% MgO and 9 wt.% AlN was sintered at 1900oC for 1 hour under 30 MPa pressure in a nitrogen gas atmosphere. Transparent polycrystalline silicon nitride was successfully fabricated. The mechanical properties such as density, hardness, young’s modulus, fracture strength and fracture toughness were evaluated. The effect of α/β phase on the mechanical properties of transparent polycrystalline silicon nitride was investigated. The properties were changed depending on the amount of α/β phase. The hardness and Young's modulus increased with increasing the volume fraction of α-phase fraction as a reflection of the higher hardness of α-phase Si3N4. The fracture toughness and fracture strength decreased with decreasing the volume fraction of β-phase Si3N4.

Ni-Induced Selective Nucleation and Solid Phase Epitaxy of Large-Grained Poly-Si on Glass

1999 ◽  
Vol 587 ◽  
Author(s):  
Rosaria A. Puglisi ◽  
Hiroshi Tanabe ◽  
Claudine M. Chen ◽  
Harry A. Atwater ◽  
Emanuele Rimini
Keyword(s):  
Amorphous Silicon ◽  
Polycrystalline Silicon ◽  
Crystalline Silicon ◽  
Solid Phase ◽  
Silicon Film ◽  
Crystallization Rate ◽  
Silicon Films ◽  
Solid Phase Epitaxy ◽  
Tem Analysis ◽  
Glass Substrates

AbstractWe investigated the formation of large-grain polycrystalline silicon films on glass substrates for application in low-cost thin film crystalline silicon solar cells. Since use of glass substrates constrains process temperatures, our approach to form large-grain polycrystalline silicon templates is selective nucleation and solid phase epitaxy (SNSPE). In this process, selective crystallization of an initially amorphous silicon film, at lithographically predetermined sites, enables grain sizes larger than those observed via random crystallization. Selective heterogeneous nucleation centers were created on undoped, 75 nm thick, amorphous silicon films, by masked implantation of Ni islands, followed by annealing at temperatures below 600 °. At this temperature, the Ni precipitates into NiSi2 particles that catalyze the transition from the amorphous to the crystalline Si phase. Seeded crystallization begins at the metal islands and continues via lateral solid phase epitaxy (SPE), thus obtaining crystallized regions of several tens of square microns in one hour. We have studied the dependence of the crystallization rate on the Ni-implanted dose in the seed, in the 5×1015/cm3 - 1016/cm3range. The large grained polycrystalline Si films were then used as a substrate for molecular beam epitaxy (MBE) depositions of 1 [.proportional]m thick Si layers. Transmission electron microscopy (TEM) analysis showed a strong correlation between the substrate morphology and the deposited layer. The layer presented a large grain morphology, with sizes of about 4 [.proportional]m.

APCVD Deposition of Si Film on SiO2 Patterned Si (111) Substrates for Solar Cells

2011 ◽  
Vol 295-297 ◽  
pp. 1211-1216
Author(s):  
Chun Yan Duan ◽  
Bin Ai ◽  
Jian Jun Lai ◽  
Chao Liu ◽  
You Jun Deng ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Polycrystalline Silicon ◽  
Silicon Film ◽  
Standard Condition ◽  
Chemical Vapor ◽  
Silicon Films ◽  
Triangular Prism ◽  
Pressure Chemical ◽  
Si Films ◽  
Surface Morphologies

We have investigated the deposition of silicon films on SiO2 patterned Si(111) substrates by atmospheric pressure chemical vapor deposition (APCVD) under standard condition. Oxidized silicon wafers with different sizes of circular and striated patterns were used as substrates for deposition of 35 μm silicon films. The influence of surface morphologies of substrates on epitaxial Si films has been discussed. The crystalline structures of the epitaxial Si films rely on the prepatterned substrates. Triangular prism-shaped grains have been obtained after depositing silicon film on substrates with circular patterns. While different size polycrystalline silicon grains appear on surfaces of Si films grown on SiO2 regions of substrates along the axis of striated patterns. Twins defects were observed in epitaxial Si films grown on SiO2 layers of the pretreated substrates.

Tensile Strength and Fracture Toughness of Surface Micromachined Polycrystalline Silicon Thin Films Prepared Under Various Conditions

1997 ◽  
Vol 505 ◽  
Author(s):  
Toshiyuki Tsuchiya ◽  
Jiro Sakata ◽  
Yasunori Taga
Keyword(s):  
Thin Films ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Polycrystalline Silicon ◽  
Electrostatic Force ◽  
Annealed Film ◽  
Process Conditions ◽  
Silicon Thin Films ◽  
Tensile Tester ◽  
Mechanical Devices

ABSTRACTA new tensile tester for thin films was developed to evaluate the reliability of the microelectro- mechanical devices. This tester uses the grip that fixes a thin film specimen to a probe by electrostatic force. We applied this tester for polycrystalline silicon (poly-Si) thin films prepared under various conditions. The microstructure of the film is controlled by the crystallizing temperature. The process conditions and the microstructures that contribute to the strength of poly-Si film are identified by the tensile strength and the fracture toughness. The mean tensile strength of each specimen size ranges from 1.8 to 3.7 GPa, and the fracture toughness calculated from the strength of the notched specimen ranges from 1.9 to 4.5 MN/m3/2. The 1000°C annealed film has higher strength and toughness than the other films because of the high annealing temperature and the small grain size. The contributions to the strength are evaluated by the additional annealing at 1000°C for the low temperature annealed films.

Redistribution of Implanted Species in Polycrystalline Silicon Films on Silicon Substrate

2007 ◽  
Vol 264 ◽  
pp. 7-12 ◽  
Author(s):  
F. Salman ◽  
J. Arnold ◽  
Peng Zhang ◽  
Guan Gyu Chai ◽  
Fred A. Stevie ◽  
...  
Keyword(s):  
Polycrystalline Silicon ◽  
Secondary Ion Mass Spectrometry ◽  
Silicon Film ◽  
Silicon Films ◽  
Si Substrates ◽  
Poly Silicon ◽  
Ar Gas ◽  
Polycrystalline Silicon Films ◽  
Secondary Ion ◽  
Diffusion Behaviors

Redistributions of implanted species after thermal annealing in polycrystalline silicon (poly-silicon) were studied by secondary ion mass spectrometry. Ten different elements were implanted into poly-silicon films grown on Si substrates. The implanted energies were chosen such that the expected ion range is within the poly-silicon film. Thermal anneals were carried out at temperatures between 300°C and 1000°C in flowing high purity Ar gas. Three different diffusion behaviors have been observed for these elements. For Be, Na, Ga, and Cr, most of the implanted ions diffused out to the surface of the poly-silicon film after anneal at 1000°C. For K, Ca, Ti, and Ge, the impurity ions diffused deeper into the bulk after anneal at 1000°C. For Cl and Mn ions, the concentration distributions became narrower when annealed at high temperatures.

The Effect of Substrate Temperature on the Crystallinity and Stress of Ion Beam Sputtered Silicon on Various Substrates

1994 ◽  
Vol 338 ◽  
Author(s):  
Cynthia G. Madras ◽  
L. Goldman ◽  
P.Y. Wong ◽  
I.N. Miaoulis
Keyword(s):  
Vapor Deposition ◽  
Polycrystalline Silicon ◽  
Physical Vapor Deposition ◽  
Ion Beam ◽  
Silicon Film ◽  
Silicon Films ◽  
Thermally Stable ◽  
Ion Beam Sputtering ◽  
Wide Range ◽  
Polycrystalline Silicon Films

ABSTRACTAmorphous and polycrystalline silicon films are commonly used in a wide range of microelectronic and optical devices. Polycrystalline silicon is conventionally deposited by chemical vapor deposition (CVD) at temperatures in excess of 600°C. At these high deposition temperatures, thermal diffusion of dopants and thermally induced chemical reactions may occur within the substrate or device. Also, substrates with low melting temperatures such as germanium, may undergo irreversible deformation. In the present study, ion beam sputtering has been shown to enable the deposition of a stable polycrystalline silicon film on germanium as well as on silicon and glass substrates at temperatures as low as 350-400°C. The crystallization properties of silicon on the different substrate surfaces is reported. Crystallinity of the ion beam sputtered silicon films as a function of deposition temperature and substrate type is measured by X-Ray diffraction. These polysilicon films are shown to be thermally stable, have randomly oriented crystals, and have good adhesion to the substrates despite high compressive deposition stresses ranging from 700MPa to 1000MPa. Magnetron sputtered silicon films deposited on substrates in the same temperature range produced only completely amorphous films, with lower stresses and which are also thermally stable. This study demonstrated the feasibility of depositing extremely hard polycrystalline silicon films on germanium and other substrates by means of physical vapor deposition at temperatures as low as 350°C.

Interface morphology of thermal oxide grown on polycrystalline silicon by different processes

1992 ◽  
Vol 50 (2) ◽  
pp. 1396-1397
Author(s):  
H. Yen ◽  
E. P. Kvam ◽  
R. Bashir ◽  
S. Venkatesan ◽  
G. W. Neudeck
Keyword(s):  
Integrated Circuits ◽  
Polycrystalline Silicon ◽  
Silicon Films ◽  
Interface Morphology ◽  
Oxide Interface ◽  
Poly Silicon ◽  
Thermal Oxide ◽  
Grain Orientations ◽  
Polycrystalline Silicon Films ◽  
P Type

Polycrystalline silicon, when highly doped, is commonly used in microelectronics applications such as gates and interconnects. The packing density of integrated circuits can be enhanced by fabricating multilevel polycrystalline silicon films separated by insulating SiO2 layers. It has been found that device performance and electrical properties are strongly affected by the interface morphology between polycrystalline silicon and SiO2. As a thermal oxide layer is grown, the poly silicon is consumed, and there is a volume expansion of the oxide relative to the atomic silicon. Roughness at the poly silicon/thermal oxide interface can be severely deleterious due to stresses induced by the volume change during oxidation. Further, grain orientations and grain boundaries may alter oxidation kinetics, which will also affect roughness, and thus stress.Three groups of polycrystalline silicon films were deposited by LPCVD after growing thermal oxide on p-type wafers. The films were doped with phosphorus or arsenic by three different methods.

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