Mechanical Properties of Thermally Crystallized Boron-Doped Silicon Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
P. Scafidi ◽  
J. Cali ◽  
E. Bustarret
Keyword(s):  
Elastic Modulus ◽  
Internal Stress ◽  
Polycrystalline Silicon ◽  
Boron Concentration ◽  
Hydrogenated Silicon ◽  
Silicon Thin Films ◽  
Boron Doped ◽  
Amorphous Hydrogenated Silicon ◽  
Polycrystalline Silicon Films ◽  
P Type

AbstractP-type polycrystalline silicon films on silicon wafers were obtained by annealing at 575 °C boron-doped amorphous hydrogenated silicon (a-Si:H) films. During the anneal, the internal stress of the film changed from compression to tension. The crystallization kinetics became faster when increasing the boron concentration. The hardness and elastic modulus of each film were determined by nanoindentation. The elastic modulus increased systematically upon crystallization. Wafer curvature monitoring during the thermal cycle allowed us to derive the thermal expansion coefficient of a-Si:H for different boron doping levels. Above a critical temperature of 320°C, the internal stress of the a-Si:H films rapidly changed toward a tensile state, independent of the boron concentration. Analysis of the hydrogen-bonding configurations by Fourier transform infrared spectroscopy indicated that this rapid stress change was due to hydrogen out-diffusion. The evolution of the internal stress with time was followed during the 575°C crystallization isothermal plateau. The circular blistering and spalling observed upon annealing in some cases of low doping levels was correlated with the presence of microvoids and with the internal stress of the a-Si:H film.

Deposition and Characterization of In-Situ Boron Doped Polycrystalline Silicon Films for Microelectromechanical Systems Applications

1999 ◽  
Vol 605 ◽  
Author(s):  
J. J. McMahon ◽  
J. J. McMahon ◽  
J. M. Melzak ◽  
C. A. Zorman ◽  
J. Chung ◽  
...  
Keyword(s):  
Polycrystalline Silicon ◽  
Microelectromechanical Systems ◽  
Single Step ◽  
Boron Doped ◽  
Polysilicon Films ◽  
Polycrystalline Silicon Films ◽  
P Type ◽  
Deposition Conditions

AbstractIn an effort to develop thick, p-type polycrystalline silicon (polysilicon) films for microelectromechanical systems (MEMS) applications, in-situ boron-doped polysilicon films were deposited by a single-step APCVD process at susceptor temperatures ranging from 700°C to 955°C. The process produces boron-doped films at a deposition rate of 73 nm/min at 955°C. Spreading resistance measurements show that the boron doping level is constant at 2 × 1019 /cm3 throughout the thickness of the films. Doped films deposited at the low temperatures exhibit compressive stress as high as 666 Mpa; however films deposited at 955°C exhibited stress as low as 130 MPa. TEM and XRD show that the microstructure strongly depends on the deposition conditions. Surface micromachined, singly clamped cantilevers and strain gauges were successfully fabricated and used to characterize the residual stress of 5.0 µm-thick doped films deposited at a susceptor temperature of 955°C.

Deposition of Polycrystalline Silicon thin Films by Plasma Enhanced CVD

1992 ◽  
Vol 283 ◽  
Author(s):  
Russell E. Hollingsworth ◽  
Pawan K. Bhat
Keyword(s):  
High Frequency ◽  
Polycrystalline Silicon ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Grain Sizes ◽  
Silicon Thin Films ◽  
Boron Doped ◽  
Capacitance Voltage ◽  
Polycrystalline Silicon Films

ABSTRACTPolycrystalline silicon films have been grown using high frequency (110 MHz) rf plasma enhanced chemical vapor deposition with a hydrogen diluted silane gas. Polycrystalline growth was obtained when the silane fraction was less than 10% of the total gas mixture for all rf powers, in marked contrast to growth at 13.56 MHz where high power and more dilution are typically required for microcrystalline growth. Grains with [111] and [220] orientations were observed to have grain sizes up to 900 Angstroms. Room temperature free carrier concentrations as low as 5 × 1015 cm-3 for undoped films were determined by capacitance voltage measurements. Boron doped microcrystalline films were grown with conductivity as high as 8 (Ωcm) V

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.

On the Temperature Dependence of Resistivity of Polycrystalline Silicon Films

1987 ◽  
Vol 106 ◽  
Author(s):  
Mark S. Rodder ◽  
Dimitri A. Antoniadis
Keyword(s):  
Numerical Calculation ◽  
Polycrystalline Silicon ◽  
Amorphous Region ◽  
Defect States ◽  
Temperature Dependent ◽  
Step Process ◽  
Dependent Potential ◽  
Si Films ◽  
Polycrystalline Silicon Films ◽  
P Type

ABSTRACTIt is shown that the grain boundary (GB) in polycrystalline-silicon (poly-Si) films need not be modeled as a temperature-dependent potential barrier or as an amorphous region to explain the temperature (T) dependence of resistivity (ρ) in p-type poly-Si films at low T. Specifically, we consider that QB defect states allow for the tunneling component of current to occur by a two-step process. Incorporation of the two-step process in a numerical calculation of ρ vs. T results in excellent agreement with available data from 100 K to 300 K.

Piezoresistive Properties of Boron-Doped PECVD Micro- and Polycrystalline Silicon films

1994 ◽  
Vol 343 ◽  
Author(s):  
M. Le Berre ◽  
M. Lemiti ◽  
D. Barbier ◽  
P. Pinard ◽  
J. Cali ◽  
...  
Keyword(s):  
Polycrystalline Silicon ◽  
Grazing Angle ◽  
Amorphous State ◽  
Silicon Films ◽  
Gauge Factor ◽  
X Ray Diffraction ◽  
Boron Doped ◽  
Polycrystalline Silicon Films ◽  
Oriented Material

ABSTRACTThe electrical and piezoresistive properties of in-situ doped PECVD silicon films deposited on oxided silicon wafers have been investigated. One series of films was deposited in the so-called microcrystalline state at 450°C. The other set of samples was deposited in the amorphous state at 320°C and subjected to rapid thermal annealing. Structural properties (grain size, texture, residual stress) were evaluated experimentally through TEM and grazing angle X ray diffraction and related to the measured gauge factor. A maximum longitudinal gauge factor of 28 is measured in the case of advantageously textured microcrystalline material, the magnitude of the gauge factor decreasing sharply for randomly oriented material. For the amorphous deposited and subsequently annealed material, the longitudinal gauge factor is in the range 22–27 depending on dopant concentration. These experimental features are compared to the results of a theoretical approach of piezoresistance in polysilicon. We derive various expressions of the gauge factor according to the assumptions of either constant stress or constant strain within the aggregate. In the case of untextured films, analytical Voigt-Reuss-Hill averages for the elements of piezoresistive and elastoresistive tensors lead to greatly simplified expressions. Theoretical estimates are shown to be in reasonable agreement with the experimental measurements. This confirms the great potential of PECVD microcrystalline and polycrystalline silicon for strain gauges.

A study of optical absorption in amorphous hydrogenated silicon thin films of varied thickness

2010 ◽  
Vol 256 (18) ◽  
pp. 5667-5671 ◽  
Author(s):  
J. Müllerová ◽  
L. Prušáková ◽  
M. Netrvalová ◽  
V. Vavruňková ◽  
P. Šutta
Keyword(s):  
Thin Films ◽  
Optical Absorption ◽  
Hydrogenated Silicon ◽  
Silicon Thin Films ◽  
Amorphous Hydrogenated Silicon

Optical absorption in PECVD deposited thin hydrogenated silicon in light of ordering effects

Open Physics ◽  
2009 ◽  
Vol 7 (2) ◽  
Author(s):  
Jarmila Müllerová ◽  
Veronika Vavruňková ◽  
Pavel Å utta
Keyword(s):  
Chemical Vapour ◽  
Optical Transmittance ◽  
Band Gap Energy ◽  
Absorption Coefficients ◽  
Hydrogenated Silicon ◽  
Transmittance Spectra ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Ordering Effects ◽  
Amorphous Hydrogenated Silicon

AbstractWe report results obtained from measurements of optical transmittance spectra carried out on a series of silicon thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) from silane diluted with hydrogen. Hydrogen dilution of silane results in an inhomogeneous growth during which the material evolves from amorphous hydrogenated silicon (a-Si:H) to microcrystalline hydrogenated silicon (µc-Si:H). Spectral refractive indices and absorption coefficients were determined from transmittance spectra. The spectral absorption coefficients were used to determine the Tauc optical band gap energy, the B factor of the Tauc plots, E 04 (energy at which the absorption coefficient is equal to 104 cm−1), and the Urbach energy as a function of the hydrogen dilution. The results were correlated with microstructure, namely volume fractions of the amorphous and crystalline phase with voids, and with the grain size.

ChemInform Abstract: UHV Study of Hydrogen Atom Induced Etching of Amorphous Hydrogenated Silicon Thin Films.

ChemInform ◽  
2010 ◽  
Vol 32 (39) ◽  
pp. no-no
Author(s):  
Thomas Zecho ◽  
Birgit D. Brandner ◽  
Juergen Biener ◽  
Juergen Kueppers
Keyword(s):  
Thin Films ◽  
Hydrogen Atom ◽  
Hydrogenated Silicon ◽  
Silicon Thin Films ◽  
Amorphous Hydrogenated Silicon

Fast Deposition of Polycrystalline Silicon Films by Hot-Wire CVD

1995 ◽  
Vol 377 ◽  
Author(s):  
A. R. Middya ◽  
A. Lloret ◽  
J. Perrin ◽  
J. Huc ◽  
J. L. Moncel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Polycrystalline Silicon ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Hot Wire ◽  
Crystalline Orientation ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Si Films ◽  
Polycrystalline Silicon Films

ABSTRACTPolycrystalline silicon thin films have been deposited at fast growth rates (50 Å/s) by hotwire chemical vapour deposition (HW-CVD) from SiH4/H2 gas mixtures at low substrate temperature (400–500°C). The surface morphology of these films consists of 0.5 – 2.0μm dendritic grains as seen by electron microscopy. The films have a columnar morphology with grains starting from the substrate either on glass or c-Si. Even the 150 nm thick initial layer is polycrystalline. The preferential crystalline orientation of the poly-Si film is apparently not governed by the radiative source but strongly depends on the type and orientation of the substrate. A strong hydrogen dilution (>90%) of silane is essential to obtain poly-Si films with optimal crystalline structure.

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