Investigation of Gaas Deep Etching by Using Reactive Ion Etching Technique

1991 ◽  
Vol 240 ◽  
Author(s):  
Kuen-Sane Din ◽  
Gou-Chung Chi
Keyword(s):  
Etch Rate ◽  
Etch Depth ◽  
Etching Technique ◽  
Deep Etching ◽  
Plasma Resistance ◽  
Initial Stage ◽  
Long Time ◽  
Critical Requirement ◽  
Inducing Surface ◽  
Etch Profile

ABSTRACTRIE is an important technique in obtaining anisotropie etch profile. This is a critical requirement for very deep etching which needs long etch duration. Among many factors which affect RIE characteristics in deep etching, the following are most concerned: (1) the etch mask: needs suitable plasma resistance without significant plasma attack for extended etch time; (2) Long time stability in etch rate and surface conditions for the sample; (3) Etch profile: should be anisotropie with tolerable undercut In this work, CCl2F2 and SiCl4 were used with CCl2F2 as the main etchant. Ar was used in the initial stage for sputtering away surface residues prior to actual etching was performed. Three types of etch masks were prepared and their performance such as plasma was investigated. Multilayer metal etch mask has very low etch rate in plasma and its etch rate selectivity is around 300. The etch selectivities of GaAs to Si3N4 and to photoresist are 35 and 23, respectively. Etch mask can be chosen depending on the thickness of etch mask and the required GaAs etch depth. The etch rate of GaAs was found significantly increased when metal mask was applied. While PR mask is easier for inducing surface coating.

Development of Multiple-Step SOI DRIE Process for Superior Notch Reduction at Buried Oxide

2011 ◽  
Vol 254 ◽  
pp. 148-151
Author(s):  
Praveen Kumar Sampath ◽  
Muhamad Khairi Bin Safari ◽  
Lee Kian Ng ◽  
Ranganathan Nagarajan
Keyword(s):  
Etch Rate ◽  
Etch Depth ◽  
Buried Oxide ◽  
High Etch Rate ◽  
Etch Profile ◽  
Multiple Step

A novel two step etch process using the Bosch-etch mechanism to prevent notching on an SOI wafer is presented. The first etch step is used to attain the maximum etch depth with high etch rate and stop before the buried oxide (BOX). Followed by the second etch step with lower etch rate and tuned to soft land on the BOX to etch the remaining depth. In addition to that it is tailored to also provide a tapered etch profile which is beneficial in reducing the notch if over etching occurs.

Innovative electrochemical deep etching technique involving aluminum thermomigration

2007 ◽  
Vol 4 (6) ◽  
pp. 2175-2179 ◽  
Author(s):  
S. Kouassi ◽  
G. Gautier ◽  
L. Ventura ◽  
J. Semai ◽  
C. Boulmer-Leborgne ◽  
...  
Keyword(s):  
Etching Technique ◽  
Deep Etching

scholarly journals 3D-Forming and Autodesk Autocad at the Initial Stage of Engineering Training of Specialists in Technical Areas

2018 ◽  
Vol 7 (3.5) ◽  
pp. 1 ◽  
Author(s):  
V V. Telegin ◽  
I V. Telegin ◽  
A S. Stepanov
Keyword(s):  
Educational Process ◽  
Descriptive Geometry ◽  
Educational Institutions ◽  
Higher Educational Institutions ◽  
Modern Computer ◽  
Initial Stage ◽  
Long Time ◽  
Higher Educational ◽  
Engineering Training ◽  
Integration Of Methods

Descriptive geometry is one of the disciplines that for a long time is the basis for training engineers of various specializations. However, with the advent of modern computer 3D technologies, the place and role in engineering of many traditional disciplines requires rethinking. The article is devoted to the integration of methods of descriptive geometry into the educational process of preparing students of higher educational institutions.   

scholarly journals A Tool to Measure Maturity of an Employee Suggestion Scheme

2015 ◽  
Vol 6 (2) ◽  
pp. 4-13 ◽  
Author(s):  
Flevy Lasrado ◽  
Boštjan Gomišček
Keyword(s):  
Building Blocks ◽  
Development Stage ◽  
Evaluation Tool ◽  
Maturity Level ◽  
Initial Stage ◽  
Long Time ◽  
Innovation Capacity ◽  
Grading Scale ◽  
Creativity And Innovation ◽  
System Effectiveness

Abstract Employee Suggestion Schemes have been used in organizations for a long time due to the fact that they enable fostering of creative ability of employees. However, they must be used effectively and in a sustainable manner to better the creativity and innovation capacity of organizations in order to improve competitive advantage. Therefore there is a need to understand the maturity of Employee Suggestion Schemes. This paper proposes a new, structured evaluation tool for assessing an organizational Employee Suggestion Scheme maturity. It suggests five building blocks: Leadership and Work Environment, System Capability, System Effectiveness, Organizational Encouragement and System Barriers, each of them characterized by several relevant indicators and an assessment/grading scale in order for an organization to be able to determine the maturity level of their Employee Suggestion Scheme as: Initial stage, Development stage or Advanced stage. Organizations should apply this tool to assess the maturity level of their Employee Suggestion Scheme and draw a roadmap for its improvements.

Effect of Pre-Oxidation on the Steam Oxidation of Heat-Resistant Steel T92

2018 ◽  
Vol 37 (8) ◽  
pp. 733-739
Author(s):  
Xu Hong ◽  
Liang Zhiyuan ◽  
Ding Jianliang ◽  
Zhao Qinxin ◽  
Guan Shipian
Keyword(s):  
Mass Gain ◽  
Oxide Thickness ◽  
Steam Oxidation ◽  
Resistant Steel ◽  
Ion Diffusion ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Initial Stage ◽  
Long Time ◽  
Lower Oxidation

AbstractEffect of pre-oxidation on the steam oxidation of T92 heat-resistant steel at 650 °C was investigated. The results show that the mass gain and the oxide thickness of T92 sample with pre-oxidation treatment were lower than that of T92 sample after exposure in steam at 650 °C. The compact and discrete Cr-rich oxide which formed on the pre-oxidized specimen hindered ion diffusion, leading to the lower oxidation rate. The effect of pre-oxidation worked at the initial stage due to the protective Cr-rich layer formed in air gas. After a long time exposure in steam, the pre-oxidation influence decreased slowly and eventually disappeared. What’s more, the adhesion property of oxide scale was improved by pre-oxidation.

Temperature Dependence of Ar Sputtering of CoSi2 Thin Films on Si and SiO2

1991 ◽  
Vol 235 ◽  
Author(s):  
Q. Z. Hong ◽  
J. M. E. Harper
Keyword(s):  
Thin Films ◽  
Temperature Dependence ◽  
Etch Rate ◽  
Elevated Temperatures ◽  
Ion Sputtering ◽  
Second Stage ◽  
Silicide Layer ◽  
Initial Stage ◽  
Co Concentration ◽  
Argon Ion

ABSTRACTThe temperature dependence of 300 eV argon ion sputtering of CoSi2 thin films in the range 50–600°C has been investigated. At temperatures above 400°C, the etch rate of CoSi2 on Si is significantly reduced, while the underlying Si reacts with the Co atoms diffusing from the silicide surface. As a result, the silicide layer effectively moves into the substrate during Ar bombardment. During sputtering of CoSi2 on Sio2, the thickness of the silicide layer decreases almost linearly with bombarding time until all the silicide is removed. Similar behavior is observed in low temperature sputtering of CoSi2 on (100) Si and evaporated Si. However, at elevated temperatures (400°C< <600°C), sputtering of CoSi2 on Si undergoes two consecutive stages. During the initial stage, the thickness of the silicide layer decreases at the same rate as that of the silicide on SiO2, and is accompanied by an enrichment in Co concentration near the surface. During the second stage, the etch rate of the silicide is reduced to only one third of the rate during the initial stage.

Gel Formation in Natural Rubber Latex: 1. Effect of (NH4)2HPO4 and TMTD/ZnO Additives

2003 ◽  
Vol 76 (5) ◽  
pp. 1177-1184 ◽  
Author(s):  
L. Tarachiwin ◽  
J. T. Sakdapipanich ◽  
Y. Tanaka
Keyword(s):  
Natural Rubber Latex ◽  
Gel Formation ◽  
Rubber Latex ◽  
Tetramethylthiuram Disulfide ◽  
Gel Content ◽  
Gel Fraction ◽  
Initial Stage ◽  
High Ammonia ◽  
Long Time ◽  
Long Storage

Abstract The rubber from commercially obtained high-ammonia latex (commercial HA-latex) increased in gel content significantly after long preservation of the latex with 1.0% w/v tetramethylthiuram disulfide (TMTD) and zinc oxide (ZnO). Deproteinization of the HA-latex did not decrease the gel content. The gel fraction of deproteinized commercial HA-latex (DPHA-latex) was not solubilized by toluene containing 1.0% ethanol, showing that the gel fraction is composed of chemically crosslinked rubber. The addition of (NH4)2HPO4, which is usually added to fresh latex (FL-latex) to remove excess amounts of Mg2+ ions by centrifugation, decreased the gel formation in FL-latex preserved with 0.6 % v/v NH4OH due to the removal of Mg2+ ions. The excess amounts of (NH4)2HPO4 accelerated the gel formation in preserved FL-latex and commercial HA-latex. The addition of 0.1% w/v TMTD/ZnO to preserved FL-latex treated with 5% w/v (NH4)2HPO4 caused an increase of gel content during storage. The gel formation in the commercial HA-latex during long time storage was presumed to be caused by excess amounts of Mg2+ ions, TMTD/ZnO and (NH4)2HPO4. Here, TMTD/ZnO accelerated the gel formation at the initial stage of storage, while (NH4)2HPO4 affected in long storage.

Feature Size and Density Effects in Wet Selective Etching of GaAs/AlAs p-HEMT Structures with Organic Acid - Peroxide Solutions.

2003 ◽  
Vol 799 ◽  
Author(s):  
Vinay S. Kulkarni ◽  
Kanti Prasad ◽  
William Quinn ◽  
Frank Spooner ◽  
Changmo Sung
Keyword(s):  
Surface Morphology ◽  
Organic Acid ◽  
Etch Rate ◽  
Low Noise ◽  
Wet Etching ◽  
Low Noise Amplifiers ◽  
Etch Depth ◽  
Feature Size ◽  
Selective Etch ◽  
Etch Stop

ABSTRACTPseudomorphic HEMT (p-HEMT) devices are used in a number of wireless communication applications including power amplifiers in the 17–50 GHz range, low noise amplifiers and switches. Selective wet etching is often used to form the gate regions of these devices to avoid plasma damage associated with dry etching. We have investigated the wet etching of small (8μm to 0.5μm) features with organic acid - hydrogen peroxide solutions. Two acid solutions were used as a selective etchant for GaAs using AlAs etch stop layers in a p-HEMT structure grown by MBE. The etched features were characterized by AFM, SEM, and TEM techniques. The etch depth uniformity and reproducibility were found to depend on a number of factors including feature size, feature density, etching chemistry, agitation and surface tension. When features with a range of size and density were placed in close proximity in a layout we found that the etch rate of the different features was a function of density, size and most importantly the etch chemistry. One etchant solution exhibited a 12% difference in etch rate from the smallest feature to the largest, while another solution exhibited uniform etching of all features regardless of size or density. Both solutions produced specular etched surfaces in GaAs and AlGaAs. However, the AlAs etch stop showed a non-uniform surface morphology after etching. The surface morphology of the AlAs etch stop is one factor that limits the over etch which can be designed into the process. The most important factors to be considered in designing a selective etch process will be presented.

Behavioural Contrast in Discrete-Trial Discriminations: Effects of Non-Reinforcement

1975 ◽  
Vol 27 (2) ◽  
pp. 259-271 ◽  
Author(s):  
Euan M. Macphail
Keyword(s):  
Response Rates ◽  
Simultaneous Presentation ◽  
Fixed Interval ◽  
Frustration Theory ◽  
Simultaneous Discrimination ◽  
Positive Trial ◽  
Discrete Trial ◽  
Initial Stage ◽  
Frequent Response ◽  
Critical Requirement

Six pigeons performed an acquisition and three reversals of a discrete trial simultaneous discrimination in which responses to the positive key were reinforced on a fixed-interval 5-s schedule; trials were terminated by either a response to the negative key or the delivery of a reinforcement. In the initial stage of acquisition and each reversal, where errors were most frequent, response rates rose and latencies fell on positive trials; these effects declined as errors decreased. The birds were also run in two yoked control conditions, and results showed that the critical requirement for the positive trial rate and latency changes was neither the simultaneous presentation of two stimuli nor the formation of a discrimination, but the occurrence of non-reinforced responses. The similarity of these phenomena to conventional behavioural contrast is emphasized, and the results are discussed in terms of frustration theory.

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