Plasma Etching Method Research Articles

Deep Anisotropic Etching of Gaas with Chlorine-Based Chemistries and SU-8 Mask Using Rie and High Density ICP Etching Methods

AbstractGaAs-based micro-electro-mechanical systems (MEMS) are emerging technologies, which will lead to integration of new sensing and actuating devices with microwave and millimeter-wave electronics. However, developing the capability of selective deep etching of GaAs is a critical issue to be solved. This paper presents a study of a highly anisotropic deep GaAs etching. Two different plasma etching methods were studied for GaAs etching with chlorine-based chemistries: reactive ion etching (RIE) with Cl2/BCl3/SiCl4mixtures and high-density inductive coupled plasma (HDICP) etching with Cl2/BCl3 mixtures. A negative acting photoresist, SU-8, which allows high resolution, high aspect ratio patterning with strong resistance to etchants, was selected as the etching mask for this work. Process parameters were varied for best results, and the effects of the process parameters are presented. Issues such as etch selectivity of SU-8 and GaAs, reflow of SU-8, and loading effects were also investigated. An optimized etching process was developed to achieve a deep etch in excess of 300μm of GaAs with a single layer of SU-8 photoresist.

Hydrogen plasma etching method for depth analysis by x-ray photoelectron spectroscopy

An etching device using a hydrogen plasma has been developed for x-ray photoelectron spectroscopy (XPS) depth profile analysis of organic compounds. The effect of the hydrogen plasma discharge was investigated using a photoresist film containing benzene rings, C– O bonds and C– F bonds formed on an Si(100) wafer. The condenser-type discharge tube employed is composed of electrodes, an etch tunnel (shield tube) and a quartz glass tube. Both the electrodes and etch tunnel have many holes. Experimental results show that the etching rate of the photoresist film is 26.7 nm min−1 at an r.f. power of 200 W, a gas flow rate of 6.0 cc min−1 and a hydrogen gas pressure of 26.6 Pa. This rate is higher than that achieved by the use of a conventional high-speed etching ion gun. It is observed that the etched surface is flatter than that obtained by parallel plate electrodes and an Ar ion beam. The amounts of C, O and F after hydrogen plasma etching were not remarkably different from those before etching, and the shape of the C 1s spectrum did not show any change, indicating no change in chemical bonding. The results show that hydrogen plasma etching is very effective for depth profile analysis of organic polymers by XPS. Copyright © 2000 John Wiley & Sons, Ltd.

SiO 2 etching characteristics in DC magnetron plasmas by using an external magnetic field

In order to create a crystal resonator with a high clock frequency, a new magnetron plasma etching method has been developed. Generation of a stable plasma over a wide range of plasma characteristics was achieved for an external magnetic field type magnetron plasma apparatus based on investigation of the relationship of discharge current and voltage of CF 4 plasmas with and without Ar and O 2 as additive gases. By using such plasmas, the etching characteristics of cultured quartz crystals (SiO 2) were studied. The etching rates were approximately 80 nm/min for CF 4 plasmas and 14 nm/min for Ar plasmas. By mixing Ar and CF 4 gases, it was confirmed that ion-assist-etching took place by both chemical and physical means. Furthermore, it was found that etching rates increased up to a maximum of 105 nm/min in a plasma mixture containing 20% O 2 Etched crystal blanks (resonators) were obtained with a thickness of less than 10 μm and with a resonant frequency with a fundamental mode of about 187 MHz.

Advanced COPNA-resin as a low temperature curing resin for high-density electronic packages

A novel type of low temperature curing resin for both LSI packages and high-density electronic packages was synthesized. The resin, named advanced COPNA-resin, was synthesized from naphthalene and 1,4-benzenedimethanol under an acid catalyst. The resin could be cured at lower temperature than generally used polyimide resin by more than 100/spl deg/C. Beside the property of low temperature curing, the new resin exhibited attractive properties as an electronic insulating material of LSI packages and high-density packages: high glass transition temperature (250/spl deg/C), low dielectric constant (/spl epsi//sub r/3.1 for 1 MHz frequency), and small water absorption (0.37 wt.%). The resin could form thin films at the film thickness range from 5 to 20 /spl mu/m when the spin speed range was from 1000 to 5000 rpm. The obtained thin films exhibited sufficient planarity in practical uses, and a precisely patterning property by a plasma etching method. In this paper, we also carried out the analysis for reaction process of the B-staged advanced COPNA-resin by using infrared absorption spectroscopy and /sup 13/C-NMR spectroscopy.

Complex solid state physical investigations of metal layers on plastics

Several plastics were coated with different metal layers. Different plasma etching methods of plastics were used before deposition of metal layers. The adhesion strength depends on etching methods. With XPS it was shown that different bonds between C-C, C-H, C-Cl and C-O are existing. With X-ray diffraction methods it was found that decreasing peak intensities depend on increasing adhesion strengths.

Plasma Etching of Copper Films Using IR Light Irradiation

ABSTRACTCopper films are etched at a low temperature of 60 °C using a Cl2 plasma etching method with IR light irradiation. The etch rate is as high as 1 μm/min. The anisotropic Cu line patterns are obtained independent of the Cl2 gas flow rate and the etching pressure conditions. Moreover, there is no corrosion on the etched sample.

Bulk wave membrane quartz resonators fabricated by a hollow cathode RF plasma etching technique

A hollow cathode maskless plasma etching method for fabrication of thin quartz membranes is presented. A special geometric arrangement of electrodes and substrates allows the complete plasma structure (plasma sheath, bulk plasma) to be transferred to the substrate area during the etching process. The process has successfully been used in preparing thin quartz membranes with plane-convex and plane-parallel shape, and thicknesses of less than 5 mum. Vibration modes in these thin quartz membranes are calculated using the method of equivalent resonant radius. The membranes are used for realization of bulk acoustic wave resonators at fundamental frequencies above 60 MHz. Good agreement between theoretical and experimental characteristics is achieved.

Determination of trace metal impurities in graphite powders by acid pressure decomposition and inductively coupled plasma atomic emission spectrometry

The complete decomposition of graphite powders by an acid pressure decomposition method was investigated. A 0.5 g amount of graphite powder was completely decomposed by pressure decomposition with a mixture of 20 ml of nitric acid and 4 ml of sulfuric acid at 250 °C for 72 h. Excess of nitric acid in the solution was removed by heating on a hot-plate, then the remainder was diluted to 50 ml with water. Lithium, Na, K, Mg, Ca, Al, Fe, Ni, Cr, Sr, Ti and V in the solution were determined by inductively coupled plasma atomic emission spectrometry. The analytical results agreed with collaborative analytical values and the values obtained using an oxygen plasma etching method. The accuracy of the proposed method was superior to that of the ashing method, because the graphite powder is decomposed in a closed system without contamination from the environment or vessels used. The relative standard deviations (n= 5) were lower than 10% at the 1 µg g–1 level of metal impurities.

Adherent metallization of carbon-fibre-reinforced plastic composites using a combined vacuum/electrochemical deposition process

Carbon-fibre-reinforced plastic composites (CFCs) were metallized using plasma etching and plasma deposition methods in combination with a conventional electrodeposition process. This new approach yields highly adherent, thick metallic layers of Cu on CFCs at economic rates. In addition, the use of environmentally hazardous chemicals can be reduced to a minimum. Dry plasma etching was applied to pretreat the CFC samples and proved to yield superior adhesion results compared to conventional wet chemical etching or mechanical treatment. Electroless-deposited copper, sputtered copper and arc-ion-plated Cu and Cr were investigated as an adhesive intermediate layer between the CFC base material and the electrodeposited Cu top coating. Arc-ion-plated Cr-Cu two-component layers and multilayers were developed, which simultaneously provide high coating adhesion for the CFC matrix and exhibit a high electric conductivity for a subsequent electrodeposition process. The adhesion was measured using a z-axis pull test and a 90° peel test.

Observation of morphology of polystyrenic materials using oxygen plasma etching

The application of the plasma etching method to determine the size distribution of polybutadiene particles in high impact polystyrene is described

Plasma Etching Methods for the Formation of Planarized Tungsten Plugs Used in Multilevel VLSI Metallizations

The vias between two levels of metal interconnect in a multilevel metal system are filled using either selective or nonselective chemical vapor deposited (CVD) tungsten. Excess tungsten is then removed from the surface of the interlayer dielectric using planarization and etch back which leaves the vias filled with tungsten plugs. The uniformity of the etch‐back process can be effected by “micro‐loading” which causes local accelerated etching of the tungsten in the vias. Other nonuniformities in etch rate, resulting in trenching around the periphery of the tungsten vias, can be caused by contaminants in the CVD reactor chamber which are incorporated in the deposited film. Methods for eliminating such problems and optimizing coverage of the plugs by the overlying metal are described.

Low-temperature reactive ion etching and microwave plasma etching of silicon

A new low-temperature reactive ion etching and microwave plasma etching method is described. Highly anisotropic silicon etching with extremely small width shifts has been performed with high selectivities of 30 for organic resist films. High etch rates of 500 and 1000 nm/min by reactive ion etching and microwave plasma etching, respectively, were achieved with a SF6 gas plasma at low wafer temperatures from −130 to −100 °C. It is concluded that lower temperatures during plasma treatment yield lower side etching and increase the dry etch resistance of organic masks.

An argon plasma etching method for the investigation of the microstructure of crazes in PVC gas pipes

An argon plasma etching method for the investigation of the microstructure of crazes in PVC gas pipes

Fabrication of a multitrack, thin-film head

Thin-film magnetic heads with a high track density of 25 tracks per 3.81 mm have been fabricated. The write current density is the same as that of the conventional sendust audio head. The head consists of a two-layer, high aspect ratio coil, formed by the reactive plasma etching method, and spin-coated PIQ varnish layers as the insulation layers to provide a smooth surface for subsequent coil layers and the Ni-Fe alloy layer.

The tadpole-shaped structures in human non-necrotizing granulomas.

We scrutinized the secondary lysosomal vesicle of the epitheloid cell from 9 patients whose biopsy specimens show multiple non-necrotizing granulomas by light microscopy (LM). In 4 of the 9 patients, we found tadpole-shaped structures (TSS) approximately tenfold larger than the size of the mycobacteriophage by transmission electron microscopy (TEM). In addition, we used a plasma etching method on epon-embedded tissue and successfully demonstrated the stereoscopic appearance of the TSS by scanning electron microscopy (SEM). The identified TSS were further analyzed with an X-ray energy dispersive spectrometer for their microchemistry. The TSS appeared to be integral structures by TEM and SEM and did not contain any nonbiologic elements when analyzed with the X-ray energy dispersive spectrometer. Their location as well as their morphologic features and microchemistry suggested that the TSS are a microorganism and related to the formation of the granulomas in our 4 patients.

Microfabrication Technique by Gas Plasma Etching Method

The gas plasma etching technique is investigated as a tool of etching micro-patterns ranged from a few microns to submicrons mainly with polycrystalline silicon films as materials to be etched. The gas plasma etching is verified to be the “nearly ideal” chemical etching. The undercutting at the top of the polycrystalline silicon film is nearly equal to the film thickness. It has been found that the etching in the diffused plasma is more suitable for etching micro-patterns and that the resist deformation is not observed after etching. The etching profile depends on the film thickness as well as on the applied RF power.

Elektrochemische Speicherung und Oxidation von Wasserstoff mit der intermetallischen Verbindung LaNi 5: H. Ewe, E. W. Justi und K. Stephan, Institute für Technische Physik der Technischen Universität Braunschweig, Mendelssohnstrasse 1B, D33 Braunschweig, Bundesrepublik, West Germany. Energy Conversion13, 109–113 (1973)

Two-dimensional (2D) transition metal dichalcogenides (TMDs) like molybdenum diselenide (MoSe2) have recently gained considerable interest since their properties are complementary to those of graphene. Unlike gapless graphene, the band structure of MoSe2 can be changed from the indirect band gap to the direct band gap when MoSe2 changed from bulk material to monolayer. This transition from multilayer to monolayer requires atomic-layer-precision thining of thick MoSe2 layers without damaging the remaining layers. Here, we present atomic-layer-precision thinning of MoSe2 nanaosheets down to monolayer by using SF6 + N2 plasmas, which has been demonstrated to be soft, selective and high-throughput. Optical microscopy, atomic force microscopy, Raman and photoluminescence spectra suggest that equal numbers of MoSe2 layers can be removed uniformly regardless of their initial thickness, without affecting the underlying SiO2 substrate and the remaining MoSe2 layers. By adjusting the etching rates we can achieve complete MoSe2 removal and any disired number of MoSe2 layers including monolayer. This soft plasma etching method is highly reliable and compatible with the semiconductor manufacturing processes, thereby holding great promise for various 2D materials and TMD-based devices.