Optimization of Pecvd Sin Films Using A Statistically Designed Experiment

1996 ◽  
Vol 446 ◽  
Author(s):  
Steven K. Brierley ◽  
Thomas E. Kazior ◽  
Lan Nguyen
Keyword(s):  
Plasma Frequency ◽  
Low Frequency ◽  
Index Of Refraction ◽  
Film Stress ◽  
Nitride Film ◽  
Bond Density ◽  
Deposition Parameters ◽  
Designed Experiment ◽  
Hydrogen Bound

AbstractA statistically designed experiment was run to optimize the deposition of PECVD SiN on GaAs substrates. Five deposition parameters were varied: RF power, temperature, pressure, plasma frequency, and ammonia/silane ratio. Four film properties were used to evaluate the quality of the nitride: the fraction of hydrogen bound to nitrogen atoms, the index of refraction (and its uniformity), thickness uniformity, and stress. From the screening phase of the experiment, it was determined that only the plasma frequency and ammonia/silane ratio influenced the quality of the nitride film. High frequency deposition was preferable to low frequency deposition since it resulted in lower film stress. The results of the optimization phase showed that SiN films with near‐zero stress, low N‐H bond density and good index of refraction could be obtained by deposition at a very low ammonia/silane ratio.

Correlation between Processing, Composition, and Mechanical Properties of PECVD-SiN, Thin Films

1990 ◽  
Vol 188 ◽  
Author(s):  
D. C. H. Yu ◽  
J. A. Taylor
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Silicon Substrate ◽  
Lattice Distortion ◽  
High Stress ◽  
Index Of Refraction ◽  
The Other ◽  
Film Stress ◽  
Intrinsic Stress ◽  
Bond Density

ABSTRACTThe inter-relationship between plasma processing, composition, and mechanical properties of PECVD-SiNx, thin films was investigated. Results showed that by varying the gas feeding ratio of NH3/SiH4N2, one can obtain PECVD-SiNx, films of different composition and streu levels. For high stress films, the deposition rate is low, values of index of refraction and Si/N ratio are small. On the other hand, film density of such films is high; values of Young's modulus and N-H/Si-H relative bond density are large. A model which correlates film stress to that contributed by (1) lattice distortion induced by Si-H and NH bondings, (2) ion bombardment, (3) thermal mismatch between PECVD-SiNx films and silicon substrate, and (4) intrinsic stress introduced during the formation of covalent Si-N bonding is proposed and examined in this work.

Dynamics of the processes in metal machining

1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Cutting Machine ◽  
Metal Machining

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.

Estimating the Quality of Thermionic Cathodes for Microwave Vacuum Tubes Using the Low-Frequency Noise Parameters

Vestnik MEI ◽  
2018 ◽  
Vol 5 (5) ◽  
pp. 120-127
Author(s):  
Mikhail D. Vorobyev ◽  
◽  
Dmitriy N. Yudaev ◽  
Andrey Yu. Zorin ◽  
◽  
...  
Keyword(s):  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Parameters ◽  
Thermionic Cathodes ◽  
Vacuum Tubes

Research of Wavelet Packet Analysis in the De-Noising of Ultrasonic Echo Signal

2011 ◽  
Vol 403-408 ◽  
pp. 1817-1822
Author(s):  
Xi Feng Zhou ◽  
Xiao Wu ◽  
Qian Gang Guo
Keyword(s):  
Signal To Noise Ratio ◽  
Wavelet Packet ◽  
Random Noise ◽  
Flaw Detection ◽  
Low Frequency ◽  
Local Analysis ◽  
Echo Signal ◽  
Wavelet Packet Analysis ◽  
Ultrasonic Flaw

The quality of ultrasonic flaw echo signal is the foundation of achieving qualitative and quantitative analysis in the in ultrasonic flaw detection. In practice, the flaw echo signals are often contaminated or even annihilation by random noise. According to the characteristics of ultrasonic flaw echo signal, wavelet packet has more accurate local analysis ability in low frequency and high frequency part. This paper discusses de-noising in ultrasonic signals based on wavelet packet analysis, and proposes an improved threshold approach for de-noising. The results show that: It remarkably raises the signal-to-noise ratio of ultrasonic flaw echo signal and improves the quality of signal with improved wavelet packet threshold.

scholarly journals Tunable Omnidirectional Band Gap Properties of 1D Plasma Annular Periodic Multilayer Structure Based on an Improved Fibonacci Topological Structure

2021 ◽  
Author(s):  
Hong-Mei Peng ◽  
Bao-Fei Wan ◽  
Peng-Xiang Wang ◽  
Dan Zhang ◽  
Hai-Feng Zhang
Keyword(s):  
Band Gap ◽  
Plasma Frequency ◽  
Incident Angle ◽  
Low Frequency ◽  
Interesting Phenomenon ◽  
Azimuthal Mode ◽  
One Dimensional ◽  
Theoretical Support ◽  
Omnidirectional Band Gap ◽  
High Reflection

Abstract In this paper, the characteristics of the omnidirectional band gap (OBG) for one-dimensional (1D) plasma cylindrical photonic crystals (PCPCs) are based on an improved Fibonacci topological (IFT) structure are studied. The influences of the azimuthal mode number, incident angle, plasma thickness, and plasma frequency on the OBG are discussed. It is concluded that increasing the azimuth modulus can significantly expand the bandwidth of the OBG, and the OBG can be moved to the low-frequency direction by increasing the plasma frequency. In addition, an interesting phenomenon can be found that when the number of azimuthal modes is equal to 2, the TM wave can produce an extra high reflection zone. It provides a theoretical support for designing the narrowband filters without introducing any physical defect layers in the structure.

Measurement of the angular motion parameters of the mirror of the scanning device

2021 ◽  
pp. 3-7
Author(s):  
Petr A. Pavlov ◽  
Elena M. Ivashchenko
Keyword(s):  
Angular Velocity ◽  
Angular Position ◽  
Low Frequency ◽  
Frequency Region ◽  
Angular Motion ◽  
Main Attention ◽  
Scanning Angle ◽  
Scanning Device ◽  
Environmental Monitoring System

A scanning device for a space-based environmental monitoring system has been investigated. The main attention is paid to the study of the parameters of the angular motion of the mirror of the scanning device, the uniformity of rotation of which largely determines the quality of the image of the Earth's surface. The principle and results of measuring the parameters of the mirror rotation carried out in a wide angular range are considered. The measurements were performed using a dynamic goniometer-autocollimator, which has been calibrated at the State Standard of Plane Angle Unit GET 22-2014. The repeatability of the average angular velocity of the scanning device mirror and the repeatability of the initial scanning angle are calculated. Nonstationarity in mathematical expectation and variance in random deviations of the angular motion of the mirror from the linear law of scanning is noted. The use of wavelet analysis revealed the frequency of excitation of oscillations in the low-frequency region of the spectrum. The possibility of using the a dynamic goniometer-autocollimator for measuring not only the angular position of the scanning device mirror, but also the angular velocity is shown.

scholarly journals Investigation of intracochlear dual actuator stimulation in a scaled test rig

2017 ◽  
Vol 3 (2) ◽  
pp. 119-122
Author(s):  
Wouter J. van Drunen ◽  
Sarra Kacha Lachheb ◽  
Anatoly Glukhovskoy ◽  
Jens Twiefel ◽  
Marc C. Wurz ◽  
...  
Keyword(s):  
Low Frequency ◽  
Acoustic Stimulation ◽  
Residual Hearing ◽  
Frequency Range ◽  
Test Rig ◽  
Profound Hearing Loss ◽  
Ongoing Research ◽  
Electric Acoustic Stimulation ◽  
Single Implant

AbstractFor patients suffering from profound hearing loss or deafness still having respectable residual hearing in the low frequency range, the combination of a hearing aid with a cochlear implant results in the best quality of hearing perception (EAS – electric acoustic stimulation). In order to optimize EAS, ongoing research focusses on the integration of these stimuli in a single implant device. Within this study, the performance of piezoelectric actuators, particularly the dual actuator stimulation, in a scaled uncoiled test rig was investigated.

Mind–body interactive qigong improves physical and mental aspects of quality of life in inpatients with stroke: A randomized control study

2019 ◽  
Vol 18 (8) ◽  
pp. 658-666 ◽  
Author(s):  
Ching-Hsiang Chen ◽  
Kuo-Sheng Hung ◽  
Yu-Chu Chung ◽  
Mei-Ling Yeh
Keyword(s):  
Quality Of Life ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Standard Care ◽  
Low Frequency ◽  
Control Group ◽  
Subacute Stroke ◽  
Interactive Exercise

Background: Stroke, a medical condition that causes physical disability and mental health problems, impacts negatively on quality of life. Post-stroke rehabilitation is critical to restoring quality of life in these patients. Objectives: This study was designed to evaluate the effect of a mind–body interactive qigong intervention on the physical and mental aspects of quality of life, considering bio-physiological and mental covariates in subacute stroke inpatients. Methods: A randomized controlled trial with repeated measures design was used. A total of 68 participants were recruited from the medical and rehabilitation wards at a teaching hospital in northern Taiwan and then randomly assigned either to the Chan-Chuang qigong group, which received standard care plus a 10-day mind–body interactive exercise program, or to the control group, which received standard care only. Data were collected using the National Institutes of Health Stroke Scale, Hospital Anxiety and Depression Scale, Short Form-12, stroke-related neurologic deficit, muscular strength, heart rate variability and fatigue at three time points: pre-intervention, halfway through the intervention (day 5) and on the final day of the intervention (day 10). Results: The results of the mixed-effect model analysis showed that the qigong group had a significantly higher quality of life score at day 10 ( p<0.05) than the control group. Among the covariates, neurologic deficit ( p=0.04), muscle strength ( p=0.04), low frequency to high frequency ratio ( p=0.02) and anxiety ( p=0.04) were significantly associated with changes in quality of life. Conversely, heart rate, heart rate variability (standard deviation of normal-to-normal intervals, low frequency and high frequency), fatigue and depression were not significantly associated with change in quality of life ( p >0.05). Conclusions: This study supports the potential benefits of a 10-day mind–body interactive exercise (Chan-Chuang qigong) program for subacute stroke inpatients and provides information that may be useful in planning adjunctive rehabilitative care for stroke inpatients.

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