Silicon Electromachining Processes in Aqueous Solutions

1998 ◽  
Vol 546 ◽  
Author(s):  
M. Kovler ◽  
D. Starosvetsky ◽  
Y. Nemirovsky ◽  
J. Yahalom
Keyword(s):  
Aqueous Solutions ◽  
Etch Rate ◽  
Cathodic Polarization ◽  
High Rate ◽  
Alkaline Solutions ◽  
Potential Range ◽  
Etched Surface

AbstractHigh rate of etching of silicon was obtained by non conventional cathodic polarization in alkaline solutions. When the process was carried out at potentials more negative than −10 V it caused electropolishing of the etched surface. Shifting the potential in the cathodic direction increases the etch-rate parabolically and enhances the effect of polishing. The etch-rate increased by more than two orders of magnitude over the potential range from −10 to −40 V, and reached the value of about 250 micron/hour at 60 °C. Additionally, the etch-rate of n-Si was found to be markedly enhanced by illumination.

Cl2-Based ECR Etching of InGaP, AlInP and AIGaP

1996 ◽  
Vol 421 ◽  
Author(s):  
J. Hong ◽  
J. W. Lee ◽  
S. J. Pearton ◽  
C. Santana ◽  
C. R. Abernathy ◽  
...  
Keyword(s):  
Microwave Power ◽  
Etch Rate ◽  
Electron Cyclotron Resonance ◽  
High Rate ◽  
Chamber Pressure ◽  
Rf Power ◽  
Polymer Addition ◽  
Ar Plasma ◽  
Etch Rates ◽  
Etched Surface

AbstractHigh microwave power (1000W) Electron Cyclotron Resonance (ECR) Cl2/Ar plasma produce etch rates for In0.5Ga0.5P, Al0.5In0.5P and Al0.5Ga0.5P of ˜1um/min. at low pressure (1.5mTorr), moderate rf power levels (150W) and room temperature. Addition of Cl2 into Ar makes much smoother etched surface morphology as well as increasing the etch rate. All parameters, including microwave power, chamber pressure and rf power increase the etch rate of these alloys. Especially, there is at least a minimum rf power in order to get much higher etch rate with increasing microwave power. AlGaP in Cl2/Ar discharges has lower etch rates than InGaP or AlInP, which is similar to the results based on CH4/H2/Ar plasma chemistries. The Cl2/Ar chemistry enables smooth, high-rate etching without the need for polymer addition and thus simplifies the processing.

An Automatic Polarization Apparatus for Electrochemical Corrosion Studies

CORROSION ◽  
1969 ◽  
Vol 25 (12) ◽  
pp. 515-519 ◽  
Author(s):  
W. D. HENRY ◽  
B. E. WILDE
Keyword(s):  
Cathodic Polarization ◽  
Reference Electrode ◽  
Electrochemical Corrosion ◽  
304 Stainless Steel ◽  
Constant Current ◽  
Voltage Source ◽  
Potential Range ◽  
Alloy Development ◽  
Corrosion Studies ◽  
Potentiodynamic Anodic Polarization

Abstract Statistical alloy development programs in which electrochemical screening techniques are used require facilities to produce precision polarization data. Conventional equipment and techniques presently available for such programs are not entirely satisfactory. Therefore, modifications were made to readily available commercial equipment to significantly improve the attainable sensitivity and reproducibility. This paper describes in detail the procedures necessary to produce an apparatus that automatically measures and records anodic and cathodic polarization curves over an applied potential range of ±2.0 volts. Traverse rates between 2 × 10−3 and 3 × 104 volts per hour are attainable and can be used to polarize electrodes through zero volts (with respect to reference electrode) without the necessity of manual switching. A special mode switch is described in detail with which the basic electronic potentiostat can be used as a constant current or constant voltage source by manual selection. The results obtained from three typical polarization experiments: (1) potentiodynamic anodic polarization, (2) galvanodynamic cathodic polarization, and (3) galvanodynamic linear polarization of AISI Type 304 stainless steel in hydrogen saturated 1N H2SO4 at 25 C (77 F), showed the performance of the apparatus to be equal to or superior to that of conventional manual procedures.

Etch Rate and Surface Morphology of Plasma Etched Glass Substrates

2000 ◽  
Vol 657 ◽  
Author(s):  
Junting Liu ◽  
Nikolay I. Nemchuk ◽  
Dieter G. Ast ◽  
J. Gregory Couillard
Keyword(s):  
Plasma Etching ◽  
Glass Ceramic ◽  
Etch Rate ◽  
Glass Ceramics ◽  
Similar Rate ◽  
Optical Mems ◽  
Glass Substrates ◽  
Rate Limiting Step ◽  
Green Glass ◽  
Etched Surface

ABSTRACTMicro-machined transparent components are of interest for optical MEMS and miniaturized biological systems. The glass ceramic GC6 developed by Corning is optically transparent, has a softening point in excess of 900°C, and a thermal expansion coefficient matched to silicon. These properties make it useful for the construction of devices that combine thin film silicon electronics with MEMS systems.Both the ceramic precursor (green glass) and the glass ceramic etch at a similar rate, about 1/3 to 1/4 of that of SiO2 etched under the same conditions, indicating that chemistry rather than microstructure control the etch rate. The cleaning steps used to clean the glass precursor profoundly influence the degree of surface roughness that develops during subsequent plasma etching. In glass ceramics, the morphology of plasma etched surface is always very smooth and independent of the cleaning steps used. Assuming that the removal of spinel crystals is the rate limiting step in plasma etching glass ceramics can explain this observation.

Elektrochemisches Verhalten der Nitrophenole und ihrer Reduktionsprodukte an Graphitelektroden/ Electrochemical Behavior of the Nitrophenols and Their Reduction Products at Graphite Electrodes

1981 ◽  
Vol 36 (7) ◽  
pp. 840-845 ◽  
Author(s):  
Elli Theodoridou ◽  
Dimitrios Jannakoudakis
Keyword(s):  
Aqueous Solutions ◽  
Electrochemical Behavior ◽  
Ph Dependence ◽  
Chemical Oxidation ◽  
Potential Range ◽  
Cyclic Voltammograms ◽  
Hanging Mercury Drop Electrode ◽  
Oxidation Peak ◽  
Graphite Electrodes ◽  
Reduction Potentials

Abstract The electrochemical reduction of the isomeric nitrophenols at graphite electrodes is investigated in aqueous solutions with pH = 1-13 and is compared with the electro-chemical oxidation of their reduction products. o-Nitrophenol and p-nitrophenol are reduced to the corresponding amines, as the observed oxidation peaks in their cyclic voltammograms can be simulated by those of o-and p-aminophenol. m-Nitrophenol is reduced to m-hydroxylaminophenol, as its oxidation peak appears at much more negative » potential than that of m-aminophenol, within the potential range of the oxidation of phenylhydroxylamine. The pH-dependence of the reduction potentials of the nitrophenols at the graphite electrodes is discussed in comparison with that at a hanging mercury drop electrode.

scholarly journals Formation of carboxylic acids during degradation of monosaccharides

2008 ◽  
Vol 26 (No. 2) ◽  
pp. 113-131 ◽  
Author(s):  
O. Novotný ◽  
K. Cejpek ◽  
J. Velíšek
Keyword(s):  
Free Radicals ◽  
Aqueous Solutions ◽  
Carboxylic Acids ◽  
Sodium Hydroxide Solution ◽  
Model Systems ◽  
Alkaline Solutions ◽  
Hydroxycarboxylic Acids ◽  
Acid Type ◽  
Cannizzaro Reaction ◽  
Benzilic Acid

The formation of low molecular carboxylic and hydroxycarboxylic acids as well as sugar and deoxysugar acids from monosaccharides (D-glucose, D-fructose, D-arabinose, DL-glyceraldehyde, and 1,3-dihydroxyacetone) was studied in three different model systems: aqueous and alkaline solutions of potassium peroxodisulfate (K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>), and sodium hydroxide solution. In total, 3 low molecular carboxylic acids (formic, acetic and propionic), 24 hydroxycarboxylic acids, and 12 corresponding lactones were identified and quantified by GC/MS. Formic, acetic, and propionic acids were isolated by extraction with diethyl ether and directly analysed by GC/MS; hydroxycarboxylic acids and their lactones were monitored as their trimethylsilylated derivatives using the same method. Formic, acetic, L-lactic, glycollic, DL-2,4-dihydroxybutanoic acids and aldonic acids derived from the parent sugars were the most abundant compounds in all model systems. Within the models investigated, the yield of carboxylic acids and hydroxycarboxylic acids (together with their lactones) ranged between 9.3–22.2% (n/n) and between 3.6–116.9% (n/n), respectively. The amount of acids was significantly lower in aqueous solutions of K<sub>2</sub>S<sub>2</sub>O<sub>8</sub> than in the alkaline solutions. The data obtained indicate that lower carboxylic acids are formed by both subsequent reactions (oxidation and/or intramolecular Cannizzaro reaction) of the sugar fragmentation products and direct decomposition of some intermediates such as uloses or hydroperoxides derived from the parent sugars. The acids possessing the original sugar skeleton are formed as a result of sugar oxidation or benzilic acid type rearrangement of deoxyuloses. Lower acids may also be formed by a recombination of free radicals.

Effects of Additive Gas on SiO2 Etching

1992 ◽  
Vol 279 ◽  
Author(s):  
Yasuhiro Miyakawa ◽  
Jun Hashimoto ◽  
Naokatsu Ikegami ◽  
Jun Kanamori
Keyword(s):  
Integrated Circuit ◽  
Vertical Profile ◽  
Etch Rate ◽  
Critical Dimension ◽  
Key Technology ◽  
Precise Control ◽  
Heavily Doped ◽  
Etched Surface ◽  
Sio2 Etching

ABSTRACTPrecise control of critical dimension(CD) loss (defined as the length of the top of contact hole minus the bottom of resist in this paper) and etched profile of contact holes is a key technology in the fabrication of Ultra Large Scaled Integrated Circuit(ULSI). In case of fine contact hole etching, small CD loss and vertical profile is essential. We have found out that N2 addition to Ar/CHF3/CF4 sharpens etched profile with CD loss kept small. And N2 addition also increases etch rate without a heavy deterioration of selectivity of SiO2 versus heavily doped n-type poly cry stall ine Si(n+ poly Si). Mechanisms of changes in etching characteristics have been investigated and discussed with the emphasis on adlayer formed on etched surface.

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