scholarly journals Synthesis and Characterization of LPCVD Polysilicon and Silicon Nitride Thin Films for MEMS Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
N. Sharma ◽  
M. Hooda ◽  
S. K. Sharma
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Silicon Nitride ◽  
Chemical Vapor ◽  
Process Conditions ◽  
Mems Devices ◽  
Material Deposition ◽  
Wide Range ◽  
Pressure Chemical ◽  
Annealing Effects

Inherent residual stresses during material deposition can have profound effects on the functionality and reliability of fabricated MEMS devices. Residual stress often causes device failure due to curling, buckling, or fracture. Typically, the material properties of thin films used in surface micromachining are not very well controlled during deposition. The residual stress, for example, tends to vary significantly for different deposition conditions; experiments were carried out to study the polysilicon and silicon nitride deposited by Low Pressure Chemical Vapor Deposition (LPCVD) method at wide range of process conditions. High temperature annealing effects on stress in case polysilicon are also reported. The reduced residual stress levels can significantly improve device performance, reliability, and yield as MEMS devices become smaller.

Microbridge Testing of Thin Films Under Small Deformation

1999 ◽  
Vol 594 ◽  
Author(s):  
T. Y. Zhang ◽  
Y. J. Su ◽  
C. F. Qian ◽  
M. H. Zhao ◽  
L. Q. Chen
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Silicon Nitride ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Chemical Vapor ◽  
Small Deformation ◽  
Nitride Film ◽  
Silicon Nitride Film ◽  
Pressure Chemical

AbstractThe present work proposes a novel microbridge testing method to simultaneously evaluate the Young's modulus, residual stress of thin films under small deformation. Theoretic analysis and finite element calculation are conducted on microbridge deformation to provide a closed formula of deflection versus load, considering both substrate deformation and residual stress in the film. Silicon nitride films fabricated by low pressure chemical vapor deposition on silicon substrates are tested to demonstrate the proposed method. The results show that the Young's modulus and residual stress for the annealed silicon nitride film are respectively 202 GPa and 334.9 MPa.

Dissolution Behavior of Silicon Nitride Thin Films in a Simulated Ocular Environment

2020 ◽  
Author(s):  
Christoph Schade ◽  
Alex Phan ◽  
Kevin Joslin ◽  
Phuong Truong ◽  
Frank Talke
Keyword(s):  
Chemical Vapor Deposition ◽  
Silicon Nitride ◽  
Vapor Deposition ◽  
Saline Solution ◽  
Protective Layer ◽  
Chemical Vapor ◽  
Dissolution Behavior ◽  
Mems Devices ◽  
Pressure Chemical ◽  
Functional Membrane

Abstract The time dependent dissolution of silicon nitride is studied in a simulated eye environment (controlled saline solution) as a function of temperature and pressure. Silicon nitride films manufactured by plasma-enhanced chemical vapor deposition (PECVD) and low-pressure chemical vapor deposition (LPCVD), respectively, were tested. The results revealed that both film types showed evidence of dissolution i.e., the films dissolved in the saline solution over time. At 37°C, PECVD and LPCVD silicon nitride membranes dissolved at a rate of 1.3 nm/day and 0.3 nm/day, respectively. It was found that at 23°C, the dissolution rate of the PECVD samples reduced to just 0.2 nm/day. Dissolution was not observed in samples tested in deionized water at 37°C. Titanium oxide layers (TiO2) were tested as protective layers to stop the dissolution. The results are important for implantable MEMS devices where silicon nitride is used as a functional membrane or as a protective layer.

scholarly journals Nanomechanical spectroscopy of ultrathin silicon nitride suspended membranes

2021 ◽  
Vol 93 (5) ◽  
pp. 50301
Author(s):  
Sanket S. Jugade ◽  
Anuj Aggarwal ◽  
Akshay K. Naik
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Silicon Nitride ◽  
Chemical Vapor ◽  
Intrinsic Stress ◽  
Nanomechanical Resonator ◽  
Pressure Chemical ◽  
Suspended Membrane ◽  
Nano Electromechanical System

Mechanical properties of a nanomechanical resonator significantly impact the performance of a resonant Nano-electromechanical system (NEMS) device. We study the mechanical properties of suspended membranes fabricated out of low-pressure chemical vapor deposited silicon nitride thin films. We fabricated doubly-clamped membranes of silicon nitride with thickness less than 50 nm and length varying from 5 to 60 μm. The elastic modulus and stress in the suspended membranes were measured using Atomic Force Microscope (AFM)-based nanomechanical spectroscopy. The elastic moduli of the suspended membranes are significantly higher than those of corresponding on-substrate thin films. We observed a reduction in net stress after the fabrication of suspended membrane, which is explained by estimating the thermal stress and intrinsic stress. We also use a mathematical model to study the stress and thickness-dependent elastic modulus of the ultrathin membranes. Lastly, we study the capillary force-gradient between the SiNx suspended membrane-Si substrate that could collapse the suspended membrane.

Residual Stress Variation in Polysilicon Thin Films

2006 ◽  
Author(s):  
Andrew J. Mueller ◽  
Robert D. White
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Compressive Stress ◽  
Chemical Vapor ◽  
Stress Variation ◽  
Wafer Curvature ◽  
Mechanical Methods ◽  
Chemical Vapor Deposited ◽  
Pressure Chemical ◽  
Deposited Films

This paper compares the use of four mechanical methods for characterization of residual stress variation in low pressure chemical vapor deposited (LPCVD) polysilicon thin films deposited, doped, and annealed under different conditions. Stress was determined using buckling structures, vibrating microstructures, static rotating structures and the wafer curvature method. After deposition of 1.0 μm of polysilicon at 625°C and 588°C the stress in the wafers is 230 MPa compressive (stdev = 1.2 MPa) and 340 MPa compressive (stdev = 10.4 MPa), respectively. Deposition of 0.6 μm at 580°C results in a tensile stress of 66 MPa (stdev= 52 MPa). Following doping, all stresses are compressive. Boron doping of the 625°C and 588°C deposited films produces a compressive stress of 149 MPa (stdev= 28.6 MPa) and 100 MPa (stdev= 29.5 MPa). Phosphorous doping of the 588°C and 580°C deposited films produces a compressive stress of 54 MPa (stdev = 0.3 MPa) and 80 MPa (stdev= 5.3 MPa), respectively. Annealing through rapid thermal processing (RTP) at temperatures of 1000°C – 1100°C reduced the stresses by 20-50 MPa, but the stresses remained compressive. These values are measured using the wafer curvature method. Values obtained from the other microstructure methods agree with stresses determined by wafer curvature with the exception of the rotating structures which showed 20% lower stress readings.

Transient Thermoreflectance Measurement of Thermal Conductivity of Nanoscale Silicon Nitride Thin Films

2007 ◽  
Author(s):  
SuYuan Bai ◽  
ZhenAn Tang ◽  
ZhengXing Huang ◽  
JiaQi Wang
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Bulk Material ◽  
Chemical Vapor ◽  
Interfacial Thermal Resistance ◽  
Silicon Nitride Films ◽  
Pressure Chemical ◽  
Material Values ◽  
Thermal Conductivities

The present work measured the thermal conductivities of the silicon nitride films prepared by lower pressure chemical vapor deposition (LPCVD) with thicknesses ranging from 100 nm to 200 nm. The measurements were made at room temperature using the transient photothermal reflectance technique, which is a non-contacting and non-destructive optical approach. The data measured were fitted by genetic algorithm to get the thermal conductivity of thin films and interfacial thermal resistance simultaneously. The results show that thermal conductivities of these films are lower than corresponding bulk material values. The interfacial thermal resistances are in the order of 10−8 m2K/W. It cannot be neglected for the very thin films. Some comparison and analysis for the results were discussed.

PHOTOLUMINESCENCE OF Si-RICH SiNx FILMS DEPOSITED BY LPCVD UNDER DIFFERENT CONDITIONS

2007 ◽  
Vol 21 (26) ◽  
pp. 4583-4592 ◽  
Author(s):  
XIAOBO WANG ◽  
YUZHEN LIU ◽  
DAPENG CHEN ◽  
LIJUN DONG ◽  
CHAO CHEN
Keyword(s):  
Thin Films ◽  
Silicon Nitride ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Silicon Nanoclusters ◽  
Amorphous Silicon Nitride ◽  
Pressure Chemical ◽  
Pl Emission ◽  
Gap States

The silicon-rich silicon-nitride thin films deposited by low pressure chemical vapor deposition at 800° C ~950° C , using dichlorosilane and ammonia as precursors, have the mosaic structure of crystallized silicon nanoclusters embedded in amorphous silicon nitride matrix, showing visible photoluminescence (PL) emission at room temperature with one to five separate peaks. The microstructures of the films change with the deposition temperatures and flux ratios of dichlorosilane to ammonia, which causes changes in the PL spectra of the films. In this paper, we report the experimental results and try to explain it with our gap states model.

A Novel Direct Liquid Injection Low Pressure Chemical Vapor Deposition System (DLI-LPCVD) for the Deposition of Thin Films

2017 ◽  
Vol 19 (8) ◽  
pp. 1700193 ◽  
Author(s):  
Mattias Vervaele ◽  
Bert De Roo ◽  
Jolien Debehets ◽  
Marilyne Sousa ◽  
Luman Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Low Pressure ◽  
Liquid Injection ◽  
Pressure Chemical ◽  
Direct Liquid Injection
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