Plasma polishing processes applied on optical materials: A review

2021 ◽  
pp. 251659842110388
Author(s):  
Hari Narayan Singh Yadav ◽  
Manjesh Kumar ◽  
Abhinav Kumar ◽  
Manas Das
Keyword(s):  
Surface Quality ◽  
Optical Materials ◽  
Gas Flow ◽  
Fused Silica ◽  
Mixed Gas ◽  
Polishing Process ◽  
Power Rate ◽  
Gas Flow Ratio ◽  
Optics Fabrication ◽  
The Impact

Nowadays, the surface quality of the material is crucial for industry and science. With the development of micro-electronics and optics, the demand for surface quality has become more and more rigorous, making optical surface polishing more and more critical. Plasma polishing technology is conceived as an essential tool for removing surface and subsurface damages from traditional polishing processes. The plasma processing technology is based on plasma chemical reactions and removes atomic-level materials. Plasma polishing can easily nano-finish hard-brittle materials such as ceramics, glass, crystal, fused silica, quartz, Safire, etc. The optical substrate with micro-level and nano-level surface roughness precision is in demand with the advancement in optics fabrication. The mechanical properties of super-finished optics materials are being used to fulfill the requirement of modern optics. This article discusses the processing of different types of freeform, complex and aspheric optical materials by the plasma polishing process used mainly by the optical industry. The plasma polishing devices developed in the last decade are thoroughly reviewed for their working principles, characteristics and applications. This article also examines the impact of various process parameters such as discharge power, rate of gas flow, mixed gas flow ratio and pressure on the plasma polishing process.

Hydrogen Concentration Analysis in Pecvd and Rtcvd Silicon Nitride Thin Films and It's Impact on Device Performance

2001 ◽  
Vol 664 ◽  
Author(s):  
C. Y. Wang ◽  
E. H. Lim ◽  
H. Liu ◽  
J. L. Sudijono ◽  
T. C. Ang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Threshold Voltage ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Gate Oxide ◽  
Nitride Film ◽  
Device Performance ◽  
Gas Flow Ratio ◽  
The Impact

ABSTRACTIn this paper the impact of the ESL (Etch Stop layer) nitride on the device performance especially the threshold voltage (Vt) has been studied. From SIMS analysis, it is found that different nitride gives different H concentration, [H] in the Gate oxide area, the higher [H] in the nitride film, the higher H in the Gate Oxide area and the lower the threshold voltage. It is also found that using TiSi instead of CoSi can help to stop the H from diffusing into Gate Oxide/channel area, resulting in a smaller threshold voltage drift for the device employed TiSi. Study to control the [H] in the nitride film is also carried out. In this paper, RBS, HFS and FTIR are used to analyze the composition changes of the SiN films prepared using Plasma enhanced Chemical Vapor deposition (PECVD), Rapid Thermal Chemical Vapor Deposition (RTCVD) with different process parameters. Gas flow ratio, RF power and temperature are found to be the key factors that affect the composition and the H concentration in the film. It is found that the nearer the SiN composition to stoichiometric Si3N4, the lower the [H] in SiN film because there is no excess silicon or nitrogen to be bonded with H. However the lowest [H] in the SiN film is limited by temperature. The higher the process temperature the lower the [H] can be obtained in the SiN film and the nearer the composition to stoichiometric Si3N4.

A Study on Pressure Stability in Double-Sided Polishing Process

2010 ◽  
Vol 126-128 ◽  
pp. 64-69
Author(s):  
Wei Li ◽  
Cheng Jin ◽  
Xiao Zhen Hu
Keyword(s):  
Surface Quality ◽  
Operation Mode ◽  
Gear Ratio ◽  
Wafer Surface ◽  
Polishing Process ◽  
Key Factor ◽  
Pressure Stability ◽  
The Stability ◽  
The Impact ◽  
Polishing Pressure

How to achieve the precision double-sided polishing process is a important issue for wafer manufacturing, it depends on machining condition such as machining environment, polishing speed, polishing operation mode, polishing pressure, polishing fluid etc. The key factor to the wafer surface quality is the stability of the polishing pressure. This paper analyzes the impact of double-sided polishing pressure in polishing process, using AMESim software to simulate the pressure standard deviation’s changes under diffrent polishing pressures, and carries out some experiments to identify the impact of polishing parameters (such as the ring gear ratio, polishing speed, polishing pressure) to the polishing pressure stability and the wafer surface quality.

Effect of CHF3/Ar Gas Flow Ratio on Self-masking Subwavelength Structures Prepared on Fused Silica Surface

2018 ◽  
Vol 33 (2) ◽  
pp. 349-355
Author(s):  
Jingjun Wu ◽  
Xin Ye ◽  
Jin Huang ◽  
Laixi Sun ◽  
Yong Zeng ◽  
...  
Keyword(s):  
Gas Flow ◽  
Silica Surface ◽  
Fused Silica ◽  
Subwavelength Structures ◽  
Flow Ratio ◽  
Gas Flow Ratio ◽  
Ar Gas

scholarly journals Study on the optical quality and strength of glass edges after the grinding and polishing process

2020 ◽  
Vol 5 (3) ◽  
pp. 411-428 ◽  
Author(s):  
Paulina Bukieda ◽  
Katharina Lohr ◽  
Jens Meiberg ◽  
Bernhard Weller
Keyword(s):  
Surface Quality ◽  
Microscopic Analysis ◽  
Optical Quality ◽  
Special Focus ◽  
Polishing Process ◽  
Research Project ◽  
Tensile Stresses ◽  
Edge Strength ◽  
The Impact ◽  
Grinding And Polishing

Abstract Glass edges result from cutting glass sheets and a further optional finishing. The mechanical interference into the brittle material glass causes flaws and cracks at the edge surface. Those defects have an influence on the strength of the whole glazing. Within the scope of a research project at the Institute of Building Construction from the Technische Universität Dresden, the grinding and polishing process is examined in terms of characteristic visible effects on the glass edge and the edge strength. Thereby a special focus of the research project is the impact of various polishing cup wheels for the chamfer surface of annealed glass. The article presents some basics about the processing steps of glass edges surfaces, introduces the considered grinding and polishing cup wheels and gives an overview of the performed experimental examinations. A microscopic analysis enables a characterisation of typical defects at the surfaces. Furthermore, four-point bending tests are performed to determine the bending tensile stresses at failure. The combination of both methods enables an analysis of the fracture-causing defect before destruction and a correlation between the optical surface quality and the bending tensile stresses. Additionally, the microscopy could be used to support the adjustment of a grinding machine and control reproducible edge qualities. The evaluation shows that a special development of polishing cup wheels for the chamfer can improve the surface quality and consequently increases the edge strength.

Investigation of Chemical Vapor Deposited Graphene Film on Oxide Substrate

2015 ◽  
Vol 815 ◽  
pp. 18-21
Author(s):  
Tao Huang ◽  
Lin Chen ◽  
Qing Qing Sun ◽  
Peng Zhou ◽  
David Wei Zhang
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Graphene Film ◽  
Chemical Vapor ◽  
Graphene Films ◽  
Gas Flow Ratio ◽  
Device Applications ◽  
Grown Graphene ◽  
The Impact

Graphene is a novel two dimensional material with exceptional properties. Chemical vapor deposition of graphene on metal substrates is widely used to prepare high quality graphene film. However, the graphene films need to be transferred to oxide substrates for device applications. A chemical vapor deposition approach for direct growth of graphene films on zinc oxide was demonstrated in the present investigation. Raman spectra were used to characterize the grown graphene films. The impact of the growth temperature, time and gas flow ratio on the layer number and crystallite size of graphene was investigated.

Carbon Nanotubes Preparation Using Carbon Monoxide from the Pyrolysis Flame

2009 ◽  
Vol 87-88 ◽  
pp. 104-109 ◽  
Author(s):  
Bao Min Sun ◽  
Yuan Chao Liu ◽  
Zhao Yong Ding
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Monoxide ◽  
Electron Microscope ◽  
Carbon Nanotube ◽  
Gas Flow ◽  
Experimental System ◽  
Spray Pyrolysis Method ◽  
Effective Diameter ◽  
Mixed Gas ◽  
The Impact

Carbon nanotube is a new kind of carbon material. Synthesis of carbon nanotubes from V-type pyrolysis flame is a kind of novel technique. It needs simple laboratory equipments and normal atmosphere pressure. The V-type pyrolysis flame experimental system is introduced. Carbon source is the carbon monoxide which is carried to the middle pipe of V-type pyrolysis flame combustor. Heat source is from acetylene /air premixed flame. Pentacarbonyl iron, served as catalyst, is transported by spray- pyrolysis method into the burner. The carbon nanotubes were characterized by scanning electron microscope and transmission electron microscope. The diameter of carbon nanotubes is approximate 20nm and its length is dozens of microns. The impact of the temperature, reactant composition and catalyst was analyzed to reveal the rule of carbon nanotube growth. Carbon nanotubes with good form and less impurity can be captured when the temperature was from 800°C to 1000°C and carbon monoxide/hydrogen/helium mixed gas flow was supplied. The effective diameter of pentacarbonyl iron nanoparticles is approximate from 5nm to 20nm in the process of carbon nanotube formation. Mechanism of carbon nanotube base on the V-type pyrolysis flame method was proposed. The carbon “dissolved-proliferation-separate out” theory can be used to explain how the pentacarbonyl iron catalyses carbon monoxide to form carbon nanotubes.

scholarly journals The High-Rate Sealed MRPC to Promote Pollutant Exchange in Gas Gaps: Status on the Development and Observations

2021 ◽  
Vol 11 (11) ◽  
pp. 4722
Author(s):  
Botan Wang ◽  
Xiaolong Chen ◽  
Yi Wang ◽  
Dong Han ◽  
Baohong Guo ◽  
...  
Keyword(s):  
Gas Flow ◽  
High Rate ◽  
Stable Operation ◽  
Beam Test ◽  
High Luminosity ◽  
Rate Test ◽  
3D Printed ◽  
Resistive Plate Chambers ◽  
The Impact ◽  
Current Behavior

This work reports the latest observations on the behavior of two Multigap Resistive Plate Chambers (MRPC) under wide high-luminosity exposures, which motivate the development and in-beam test of the sealed MRPC prototype assembled with low-resistive glass. The operation currently being monitored, together with previous simulation results, shows the impact of gas pollution caused by avalanches in gas gaps, and the necessity to shrink the gas-streaming volume. With the lateral edge of the detector sealed by a 3D-printed frame, a reduced gas-streaming volume of ~170 mL has been achieved for a direct gas flow to the active area. A high-rate test of the sealed MRPC prototype shows that, ensuring a 97% efficiency and 70 ps time resolution, the sealed design results in a stable operation current behavior at a counting rate of 3–5 kHz/cm2. The sealed MRPC will become a potential solution for future high luminosity applications.

Two-Phase Flows in Mini-/Micro-Gas Flow Channels of PEM Fuel Cells

2013 ◽  
Author(s):  
Sung Chan Cho ◽  
Yun Wang
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Fluid Model ◽  
Pem Fuel Cells ◽  
Two Phase ◽  
Micro Gas Flow ◽  
Two Fluid Model ◽  
The Impact ◽  
Two Fluid ◽  
Phase Pressure

In this paper, two-phase flow dynamics in a micro channel with various wall conditions are both experimentally and theoretically investigated. Annulus, wavy and slug flow patterns are observed and location of liquid phase on different wall condition is visualized. The impact of flow structure on two-phase pressure drop is explained. Two-phase pressure drop is compared to a two-fluid model with relative permeability correlation. Optimization of correlation is conducted for each experimental case and theoretical solution for the flows in a circular channel is developed for annulus flow pattern showing a good match with experimental data in homogeneous channel case.

Carbon Nanotube-Induced Planarization of Conjugated Polymers in Solution

2004 ◽  
Vol 858 ◽  
Author(s):  
Jian Chen ◽  
Rajagopal Ramasubramaniam ◽  
Haiying Liu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Conjugated Polymers ◽  
Spectroscopic Study ◽  
Surface Quality ◽  
Hybrid Materials ◽  
Conjugated Polymer ◽  
Visible Absorption ◽  
The Impact ◽  
Conformational Interaction

ABSTRACTThe understanding of the conformational interaction between conjugated polymers and carbon nanotubes in solution is essential to develop the applications of carbon nanotubes, particularly conjugated polymer-carbon nanotube hybrid materials. The visible absorption spectroscopic study shows that curved carbon nanotube surfaces can induce the planarization of individual conjugated polymers such as poly(p-phenyleneethynylene)s and poly(3-alkylthiophene)s in solution. The impact of nanotube surface quality on the interaction between carbon nanotubes and conjugated polymers is investigated.

High Performance MEMS Thermal Gyroscope

2012 ◽  
Author(s):  
Nilgoon Zarei ◽  
Albert M. Leung ◽  
John D. Jones
Keyword(s):  
External Force ◽  
High Performance ◽  
Gas Flow ◽  
Element Model ◽  
Minimal Impact ◽  
Mems Gyroscope ◽  
Force Finding ◽  
Dimensional Finite Element ◽  
To Come ◽  
The Impact

This paper reports modeling a new design of Thermal MEMS gyroscope through the use of the Comsol Multiphysics software package. Being very small and having no movable parts have made thermal MEMS gyroscope very practical. Previously designed Thermal MEMS gyroscope shows some limitation such as being vulnerable to gravity force. Finding a technique to increase the range of thermal MEMS gyroscope reliability motivated us to come up with a new design that we will refer to as the ‘Forced Convection MEMS gyroscope’. A two-dimensional finite-element model of the device has been developed to investigate its performance. An external force has been introduced to the system to create a higher-velocity hot gas stream that will be deviated more in response to rotation. The external force should be great enough that convection currents resulting from gravity or acceleration will have minimal impact on the gyroscope sensitivity. A heating element can still be used, but its primary purpose is now to warm the flowing gas so that it can be detected by the sensors. In this paper we will also show that, in order to completely eliminate the impact of gravity and increase the sensitivity of the gyroscope, it is possible to eliminate the heaters entirely and instead use heated sensors to detect gas currents. In other words, the sensors are working as hot-wire anemometers. Our simulations suggest that this design variant results in higher sensitivity. We have also carried out optimization studies to identify the best location for the heaters and sensors. A prototype of this device has been fabricated based on MEMS techniques, and an external pump is used to produce an oscillating gas flow within the device.

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