Showing papers on "Etching (microfabrication) published in 2000"

Metal-assisted chemical etching in HF/H2O2 produces porous silicon

Abstract: A simple and effective method is presented for producing light-emitting porous silicon (PSi) A thin (d<10 nm) layer of Au, Pt, or Au/Pd is deposited on the (100) Si surface prior to immersion in a solution of HF and H2O2 Depending on the type of metal deposited and Si doping type and doping level, PSi with different morphologies and light-emitting properties is produced PSi production occurs on the time scale of seconds, without electrical current, in the dark, on both p- and n-type Si Thin metal coatings facilitate the etching in HF and H2O2, and of the metals investigated, Pt yields the fastest etch rates and produces PSi with the most intense luminescence A reaction scheme involving local coupling of redox reactions with the metal is proposed to explain the metal-assisted etching process The observation that some metal remains on the PSi surface after etching raises the possibility of fabricating in situ PSi contacts

Infrared Spectral Evidence for the Etching of Carbon Nanotubes: Ozone Oxidation at 298 K

Abstract: Single-walled nanotubes (SWNTs) are an interesting new molecular form of carbon in the fullerene family, first reported by Iijima in 1991.1 Intense research activity is now focused on these molecules2 and many applications are envisioned.2 It is necessary to understand the chemical processes and functionalization of SWNTs in order to pursue these applications. FTIR is one of the powerful techniques available to researchers to study these surface properties.3 For example, we have recently used transmission FTIR to study the thermal decomposition of carboxyl and quinone functional groups formed by acidic cutting of the SWNTs.4 These groups, located at the ends and at surface defect sites on the nanotubes,2,5-8 block the entry ports for Xe adsorption on the interior of the SWNTs.9 We report here FTIR spectroscopic studies of the oxidation and etching of SWNTs using ozone at 298 K, and the subsequent thermal stability of the oxygenated groups. It has been shown through microscopy that reactions appear to begin at the end caps or kink sites of the SWNTs, followed by reaction at the rim sites that remain after the end caps and kink sites are etched away.6,7,10 The enhanced reactivity of the end caps and kink sites, compared to the reactivity of the walls, can be understood by the increased strain at these sites causing a partial loss of conjugation.8 In fact, forming a hole at the end cap by oxidation has been calculated to be much more energetically favorable (9 eV) than formation of holes on the walls.11 Ozonolysis is a common way to oxidatively break carboncarbon double bonds at low temperatures.12-14 Studies of the reaction of ozone with C60 and C70 have been reported in detail (see for example refs 15-17). However, the reaction of ozone with carbon nanotubes has been mentioned only briefly,16,17 and no spectroscopic studies have been carried out. The SWNTs used in this study have a distribution of diameters near that of a (10,10) tube (13.6 Å).18 The final sample consists of a mixture of open and closed-end SWNTs.19 The samples were deposited via the drop/dry technique from a methanol suspension onto CaF2 pressed into a tungsten grid clamped between electrical leads. This sample and a bare CaF2 blank were then mounted in a stainless steel FTIR cell20 used previously for transmission studies of powders and dispersed opaque materials.21 The sample was heated to 373 K overnight in a vacuum (1 × 10-6 Torr after 16 h) to remove the solvent, followed by heating to 1073 K in a vacuum to remove most of the oxygen-containing functional groups on the original SWNT sample.4 This heating revealed the IR-active phonon mode of SWNTs near 1580 cm-1.4 The ozone was prepared at an initial purity of 97% (3% O2) in a corona discharge-based trapping and purification system described elsewhere22 and O3(g) was transferred directly to the FTIR cell. The initial ozone purity in the FTIR system was determined to be ∼70% O3 (g) due to decomposition on the stainless steel walls of the apparatus. Figure 1 presents the IR spectral changes of the SWNT sample caused by O3 exposure at 298 K. The spectral bands that develop at 1739, 1200, and 1040 cm-1 are indicative of the production of ester groups. The band at 1650 cm-1 is assigned to the CdO stretching mode of quinone groups, while the band at 1581 cm-1 is assigned to CdC double bonds located near the newly formed oxygenated groups.23,24 The origin of the bands at 1380 and 925 (1) Iijima, S. Nature 1991, 354, 56. (2) Dresselhaus, M. S.; Dresselhaus, G.; Eklund, P. C. Science of Fullerenes and Carbon Nanotubes; Academic Press: San Diego, 1996. (3) Vibrational Spectroscopy of Molecules on Surfaces Yates; J. T., Jr., Madey, T. E., Eds.; (Plenum: New York, 1987). (4) Kuznetsova, A.; Mawhinney, D. B.; Naumenko, V.; Yates, J. T., Jr.; Liu, J.; Smalley, R. E. Chem. Phys. Lett., in press. (5) Liu, J.; Rinzler, A. G.; Dai, H.; Hafner, J. H.; Bradley, R. K.; Boul, P. J.; Lu, A.; Iverson, T.; Shelimov, K.; Huffman, C. B.; Rodriguez-Macias, F.; Shon, Y. S.; Lee, T. R.; Colbert, D. T.; Smalley, R. E. Science 1998, 280, 1253. (6) Tsang, S. C.; Harris, P. J. F.; Green, M. L. H. Nature 1993 362, 520. (7) Ajayan, P. M.; Ebbesen, T. W.; Ichihashi, T.; Iijima, S.; Tanigaki, K.; Hiura, H. Nature 1993, 362, 522. (8) Srivastava, D.; Brenner, D. W.; Schall, J. D.; Ausman, K. D.; Yu, M. F.; Ruoff, R. S. J. Phys. Chem. B 1999, 103, 4330. (9) Kuznetsova, A.; Yates, J. T., Jr.; Liu, J.; Smalley, R. E. J. Chem. Phys., in press. (10) Ajayan, P. M.; Iijima, S. Nature 1993, 361, 333. (11) Mazzoni, M. S. C.; Chacham, H.; Ordejon, P.; Sanchez-Portal, D.; Soler, J. M.; Artacho, E. Phys. ReV. B 1999, 60, R2208. (12) Morrison, R. T.; Boyd, R. N. Organic Chemistry, 4th ed.; Allyn and Bacon: Boston, 1983. (13) Neeb, P.; Horie, O.; Moortgat, G. K. J. Phys. Chem. A 1998, 102, 6778. (14) Manoilova, O. V.; Lavalley, J. C.; Tsyganenko, N. M.; Tsyganenko, A. A. Langmuir 1998, 14, 5813. (15) Malhotra, R.; Kumar, S.; Satyam, A. J. Chem. Soc., Chem. Commun. 1994, 1339. (16) Deng, J. P.; Mou, C. Y.; Han, C. C. Fullerene Sci. Technol. 1997, 5, 1033. (17) Deng, J. P.; Mou, C. Y.; Han, C. C. Fullerene Sci. Technol. 1997, 5, 1325. (18) Rinzler, A. G.; Liu, J.; Dai, H.; Nikolaev, P.; Huffman, C. B.; Rodrı́guez-Macı́as, F. J.; Boul, P. J.; Lu, A. H.; Heymann, D.; Colbert, D. T.; Lee, R. S.; Fischer, J. E.; Rao, A. M.; Eklund, P. C.; Smalley, R. E. Appl. Phys. A. 1998, 67, 29. (19) Smalley, R. E., personal communication. (20) Basu, P.; Ballinger, T. H.; Yates, J. T., Jr. ReV. Sci. Instrum. 1988, 59, 1321. (21) Mawhinney, D. B.; Rossin, J. A.; Gerhart, K. Yates, J. T., Jr. Langmuir 1999, 15, 5, 4617. (22) (a) Yates, J. T., Jr. Experimental InnoVations in Surface Science; AIP/ Springer-Verlag, New York, 1998; p 702. (b) Zhukov, V.; Popova, I.; Yates, J. T., Jr. J. Vac. Sci. Technol. A, accepted for publication. (23) Socrates, G. Infrared Characteristic Group Frequencies; John Wiley & Sons: New York, 1980. (24) Fanning, P. E.; Vannice, M. A. Carbon 1993, 31, 721. Figure 1. Infrared modes resulting from the ozonation of SWNTs. The background spectrum of the nanotubes before ozone exposure has been subtracted so that the changes can be more clearly observed. Both CO2(g) and CO(g) are formed as well. 2383 J. Am. Chem. Soc. 2000, 122, 2383-2384

Silicon VLSI Technology: Fundamentals, Practice and Modeling

Abstract: (NOTE: Chapters 3-11 include an Introduction, Historical Development and Basic Concepts, Manufacturing Methods and Equipment, Measurement Methods, Models and Simulation, Limits and Future Trends in Technologies and Models, Summary of Key Ideas, References, and Problems.) 1. Introduction and Historical Perspective. Introduction. Integrated Circuits and the Planar Process-Key Inventions That Made It All Possible. Semiconductors. Semiconductor Devices. Semiconductor Circuit Families. Modern Scientific Discovery-Experiments, Theory and Computer Simulation. The Plan for This Book. 2. Modern CMOS Technology. CMOS Process Flow. 3. Crystal Growth, Wafer Fabrication and Basic Properties of Silicon Wafers. 4. Semiconductor Manufacturing- Clean Rooms, Wafer Cleaning and Gettering. 5. Lithography. 6. Thermal Oxidation and the Si/SiO2 Interface. 7. Dopant Diffusion. 8. Ion Implantation. 9. Thin Film Deposition. 10. Etching. 11. Backend Technology.

Evaluation of size effect on mechanical properties of single crystal silicon by nanoscale bending test using AFM

Abstract: This paper describes a nanometer-scale bending test for a single crystal silicon (Si) fixed beam using an atomic force microscope (AFM). This research focuses on revealing the size effect on the mechanical property of Si beams ranging from a nano- to millimeter scale. Nanometer-scale Si beams, with widths from 200 to 800 nm and a thickness of 255 nm, were fabricated on an Si diaphragm by means of field-enhanced anodization using AFM and anisotropic wet etching. The efficient condition of the field-enhanced anodization could be obtained by changing the bias voltage and the scanning speed of the cantilever. Bending tests for micro- and millimeter-scale Si beams fabricated by a photolithography technique were also carried out using an ultraprecision hardness tester and scratch tester, respectively. Comparisons of Young's modulus and bending strength, of Si among the nano-, micro-, and millimeter scales showed that the specimen size did not have an influence on the Young's modulus in the [110] direction, whereas it produced a large effect on the bending strength. Observations of the fractured surface and calculations of the clack length from Griffith's theory made it clear that the maximum peak-to-valley distance of specimen surface caused the size effect on the bending strength.

Self-ordered pore structure of anodized aluminum on silicon and pattern transfer

Abstract: A practical approach of transferring a hexagonal array of nanosized pores produced in porous alumina into silicon and other substrates is discussed. The alumina pores have dimensions of 25–250 nm pore diameters and 50–300 nm pore spacings depending on the anodization conditions used. The characteristics of the alumina pores and the alumina–silicon interface are studied for different substrate materials and anodizing conditions. The unique structure of the barrier layer allows for the alumina to be directly used as an etch mask for pattern transfer into the silicon substrate.

Supercritical etching compositions and method of using same

Abstract: A supercritical etching composition and method for etching an inorganic material of a semiconductor-based substrate are provided. The method includes providing a semiconductor-based substrate having an exposed inorganic material and exposing the substrate to the supercritical etching composition, whereby exposed inorganic material is removed from the substrate. In one embodiment, the supercritical etching composition includes a supercritical component, which is not capable of etching a particular exposed inorganic material, and a nonsupercritical etching component, which is capable of etching the particular exposed inorganic material. In another embodiment, the supercritical etching composition includes a supercritical component, which is capable of etching the particular exposed inorganic material.

Etching Mechanism of Vitreous Silicon Dioxide in HF-Based Solutions

Abstract: A reaction mechanism is proposed for the dissolution process of silicon dioxide networks in aqueous HF-based solutions. Etch experiments with thermally grown silicon dioxide were used to create a model for the etch process. Literature data on the etching of other vitreous silicon dioxide materials were used to refine the model. A new method, using a quartz microbalance, is used to monitor the etch rate in situ and to establish the reactive species. The first reaction step determines the rate of the etch process. It is the substitution of a surface SiOH group, which is bonded to three bridging oxygen atoms, by an SiF group. Due to an acid/base equilibrium reaction of the silanol groups on the surface with its protonated and deprotonated forms, the substitution reaction rate is pH dependent. At low pH ( 1.5), the elimination of...

Differences in anisotropic etching properties of KOH and TMAH solutions

Abstract: We compared the anisotropic etching properties of KOH and TMAH solutions. We used hemispherical specimens of single-crystal silicon whose surface exhibited every crystallographic orientation, in order to evaluate the etching properties as a function of the orientation. We carried out a series of experiments using different etchant concentrations and etching temperatures. The orientation dependence in the etching rates of the surface crystals significantly differed between the two etchants, especially for the (111) and (221) planes. We conclude that the two etchants have different etching mechanisms at least in an area including these two planes. The etching rates varied with etchant concentration and etching temperature. The concentrations that maximized the etching rate were 25 wt.% for KOH and 20 wt.% for TMAH. The activation energies in KOH and TMAH were almost the same for the (100), (110), and (320) planes but not for the (221) and (111) planes. Etchant circulation had a significant effect on the etching rates in diluted TMAH solution but not in KOH solution. The roughness of the (100) plane in KOH was one order smaller than that in TMAH.

Micromachining of buried micro channels in silicon

Abstract: A new method for the fabrication of micro structures for fluidic applications, such as channels, cavities, and connector holes in the bulk of silicon wafers, called buried channel technology (BCT), is presented in this paper. The micro structures are constructed by trench etching, coating of the sidewalls of the trench, removal of the coating at the bottom of the trench, and etching into the bulk of the silicon substrate. The structures can be sealed by deposition of a suitable layer that closes the trench. BCT is a process that can be used to fabricate complete micro channels in a single wafer with only one lithographic mask and processing on one side of the wafer, without the need for assembly and bonding. The process leaves a substrate surface with little topography, which easily allows further processing, such as the integration of electronic circuits or solid-state sensors. The essential features of the technology, as well as design rules and feasible process schemes, will be demonstrated on examples from the field of /spl mu/-fluidics.

Etch method using a dielectric etch chamber with expanded process window

Abstract: A method for etching a dielectric in a thermally controlled plasma etch chamber with an expanded processing window The method is adapted to incorporate benefits of a the thermal control and high evacuation capability of the chamber Etchent gases include hydrocarbons, oxygen and inert gas Explanation is provided for enablling the use of hexafluoro-1,3-butadiene in a capacitively coupled etch plasma The method is very useful for creating via, self aligned contacts, dual damascene, and other dielectric etch

Reactive ion beam etching method and a thin film head fabricated using the method

Abstract: A reactive ion beam etching method which employs an oxidizing agent in a plasma contained in an ion source (10) to control carbonaceous deposit (e.g., polymer) formation within the ion source and on the substrate. After operating the ion source with a plasma having a carbonaceous deposit forming species, a plasma (Ar+O2ions) containing an oxidizing agent (species) is generated within the ion source. Preferably, within the ion source a plasma is maintained essentially continuously between the time that the carbonaceous deposit forming species is present and the time that the oxidizing agent is present. Preferably, a reactive ion beam containing an oxidizing species is incident upon the sample at an angle which enhances the selectivity of the carbonaceous deposit (e.g., polymer) etching relative to other materials upon which the ion beam impinges. A thin film magnetic head (52, 54, 56, 58) is fabricated according to a pole (52, 58) trimming process which employs RIBE with an oxidizing species to remove any carbonaceous material (e.g., polymer) deposits formed during a previous fluorocarbon based RIBE step.

Microscale material testing of single crystalline silicon: process effects on surface morphology and tensile strength

Abstract: The mechanical properties of single-crystalline silicon are measured by uniaxial tension tests from microscale beam specimens patterned by four different common silicon etchants — KOH, EDP, TMAH and XeF2. SOI wafers are used to prepare test samples, which are 3–5 μm thick, 20–100 μm wide, and 6 mm long beam specimens; these are monolithically mounted on a temporary frame. A uniaxial tension test has been designed to accommodate microscale test requirements such as sample handling, sample alignment, and friction elimination. Stress and strain are measured using a commercial load cell and a laser interferometry system, respectively. Young's modulus of silicon in the 〈110〉 direction is measured to be 169.2±3.5 GPa, very close to the widely accepted value of 168.9 GPa obtained from a macroscale sample by an ultrasonic method. The fracture strength in the 〈110〉 direction is measured to vary from 0.6 to 1.2 GPa, and is apparently affected by the etching process employed to make the microscale specimen. As surface defects are expected to be the main factor determining the strength of the specimen, surface morphology is examined not only as a function of etchants but also as a function of mask-to-crystal direction misalignment after KOH etching. In the case of samples prepared by KOH etching, measured fracture strengths are 0.94 and 0.72 GPa from samples with 0° and 2° misalignments, respectively.

Nanostructured Thin Films of Organic–Organometallic Block Copolymers: One-Step Lithography with Poly(ferrocenylsilanes) by Reactive Ion Etching

Abstract: The deposition of thin films of inorganic nanoclusters as a route to one-step lithography has been achieved using block copolymers with inherent inorganic (Fe and Si) components. Nanodomains of the organometallic part are resistant to removal during the subsequent O2 etch, which results in well-ordered and separate domains of iron and silicon oxides, as can be seen in the Figure.

Gas pulsing for etch profile control

Abstract: Etch profile control with pulsed gas flow and its applications to etching such as anisotropic etching of high aspect ratio features and etching of self-aligned contact structures in various processes. Pulsing can be applied according to this invention to the flow rate of a gas such as an etchant gas, a gas that leads to the deposition of a protective layer, a gas that modifies the deposition of a protective layer, and a gas that modifies etching.

40% efficient thin-film surface-textured light-emitting diodes by optimization of natural lithography

Abstract: In conventional light-emitting diodes (LEDs), the external efficiency is limited by total internal reflection at the semiconductor-air interface. The problem can be overcome by the concept of the nonresonant cavity LED, which is an LED with a textured top surface and a rear reflector. The surface is textured using natural lithography. A monolayer of randomly positioned polystyrene spheres acts as a mask for dry etching. We present details about the optimization of the parameters of the texturing process for GaAs/AlGaAs LEDs. The studied parameters are the size of the spheres, the distribution of the spheres on the surface and the etching depth. Using optimized texturing conditions, we have realized un-encapsulated top-emitting oxide-confined GaAs/AlGaAs nonresonant cavity LEDs with an external quantum efficiency of 40%.

Plasma processing of tungsten using a gas mixture comprising a fluorinated gas and oxygen

Abstract: A method and apparatus for etching of a substrate comprising both a polysilicon layer and an overlying tungsten layer. The method comprises etching the tungsten layer in a chamber using a plasma formed from a gas mixture comprising a fluorinated gas (such as CF4, NF3, SF6, and the like) and oxygen.

Apparatus and methods for upgraded substrate processing system with microwave plasma source

Abstract: An apparatus and methods for an upgraded CVD system that provides a plasma for efficiently cleaning a chamber, according to a specific embodiment. Etching or depositing a layer onto a substrate also may be achieved using the upgraded CVD system of the present invention. In a specific embodiment, the present invention provides an easily removable, conveniently handled, and relatively inexpensive microwave plasma source as a retrofit for or a removable addition to existing CVD apparatus. In a preferred embodiment, the remote microwave plasma source efficiently provides a plasma without need for liquid-cooling the plasma applicator tube. In another embodiment, the present invention provides an improved CVD apparatus or retrofit of existing CVD apparatus capable of producing a plasma with the ability to efficiently clean the chamber when needed.

Step and flash imprint lithography for sub-100-nm patterning

Abstract: Step and Flash Imprint Lithography (SFIL) is an alternative to photolithography that efficiently generates high aspect-ratio, sub-micron patterns in resist materials. Other imprint lithography techniques based on physical deformation of a polymer to generate surface relief structures have produced features in PMMA as small as 10 nm, but it is very difficult to imprint large depressed features or to imprint a thick films of resist with high aspect-ratio features by these techniques. SFIL overcomes these difficulties by exploiting the selectivity and anisotropy of reactive ion etch (RIE). First, a thick organic 'transfer' layer (0.3 micrometer to 1.1 micrometer) is spin coated to planarize the wafer surface. A low viscosity, liquid organosilicon photopolymer precursor is then applied to the substrate and a quartz template applied at 2 psi. Once the master is in contact with the organosilicon solution, a crosslinking photopolymerization is initiated via backside illumination with broadband UV light. When the layer is cured the template is removed. This process relies on being able to imprint the photopolymer while leaving the minimal residual material in the depressed areas. Any excess material is etched away using a CHF3/He/O2 RIE. The exposed transfer layer is then etched with O2 RIE. The silicon incorporated in the photopolymer allows amplification of the low aspect ratio relief structure in the silylated resist into a high aspect ratio feature in the transfer layer. The aspect ratio is limited only by the mechanical stability of the transfer layer material and the O2 RIE selectivity and anisotropy. This method has produced 60 nm features with 6:1 aspect ratios. This lithography process was also used to fabricate alternating arrays of 100 nm Ti lines on a 200 nm pitch that function as efficient micropolarizers. Several types of optical devices including gratings, polarizers, and sub-wavelength structures can be easily patterned by SFIL.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Method of producing silicon thin film, method of constructing SOI substrate and semiconductor device

Abstract: To decrease the thickness of a silicon thin film to a desired value without deterioration of the quality thereof while avoiding the surface roughness due to speed increasing oxidation of crystal defect portions occurring when conducting the conventional sacrificial oxidation, effect of dust particles, etc. and also avoiding deterioration of high pressure resistance of the oxide film associated with the surface roughness. A silicon ultrathin film SOI layer is produced in the following two steps: preparing a SOI wafer having a silicon thin film, which exhibits less precipitation of oxygen, thereon by the SIMOX method or the semiconductor bonding method, and cleaning the SOI wafer with an alkali solution such as SC1 and TMAH, so as to utilize the etching action of the aqueous cleaner.

Dislocation density in GaN determined by photoelectrochemical and hot-wet etching

Abstract: Defects in GaN layers grown by hydride vapor-phase epitaxy have been investigated by photoelectrochemical (PEC) etching, and by wet etching in hot H3PO4 acid and molten potassium hydroxide (KOH). Threading vertical wires (i.e., whiskers) and hexagonal-shaped etch pits are formed on the etched sample surfaces by PEC and wet etching, respectively. Using atomic-force microscopy, we find the density of “whisker-like” features to be 2×109 cm−2, the same value found for the etch-pit density on samples etched with both H3PO4 and molten KOH. This value is comparable to the dislocation density obtained in similar samples with tunneling electron microscopy, and is also consistent with the results of Youtsey and co-workers [Appl. Phys. Lett. 73, 797 (1998); 74, 3537 (1999)].

Self-trimming method on looped patterns

Abstract: A method of self-trimming pattern, includes forming a pattern containing a plurality of regular or irregular features within a first material deposited on a substrate, depositing a conformal layer of second material, and etching the second material to form spacers of the second material along the sidewalls of the features in the first material.

Semiconductor device and manufacture thereof

Abstract: PROBLEM TO BE SOLVED: To provide a manufacture for a semiconductor device capable of preventing a shape failure of a hole and reducing an electrical failures such as short-circuit, and to provide the semiconductor device. SOLUTION: In a manufacture of a semiconductor device, after a BPSG film 110 is formed on a silicon substrate 100, an auxiliary hole 120 is formed which reaches a specified depth at a position forming a contact hole 118 of the BPSG film 110 and has a diameter larger than the contact hole 118. Thus, a polysilicon sidewall 114 formed in a side part of a polysilicon film 112 is formed at the sometime in a sidewall of the auxiliary hole 120. As a result, by the use of an etching mask 116 comprising the polysilicon film 112 and the polysilicon sidewall 114, a contact hole 118 having no shape failure can be formed.

Integrated shallow trench isolation approach

Abstract: A method for processing a silicon substrate disposed in a substrate process chamber includes transferring the substrate into the substrate process chamber. The substrate having a hard mask formed thereon and a patterned photoresist overlying the hard mask to expose portions of the hard mask. The chamber being the type having a source power system and a bias power system. The method further includes etching the exposed portions of the hard mask to expose portions of the silicon substrate underlying the hard mask. Thereafter, the patterned photoresist is exposed to a first plasma formed from a first process gas to remove the photoresist from the hard mask. Thereafter, the exposed silicon substrate is etched by exposing the substrate to a second plasma formed from a second process gas by applying RF energy from the source power system and biasing the plasma toward the substrate. The substrate is transferred out of the substrate processing chamber.

Method for making a semiconductor device comprising a stack alternately consisting of silicon layers and dielectric material layers

Abstract: The invention concerns a method for making a semiconductor device consisting of a silicon substrate whereon is formed a stack of layers. The stack comprises at least first and second successive assemblies each consisting, relative to the substrate, a thin lower SiGe layer and a thin upper silicon layer. It consists in forming on the thin upper silicon layer of the second assembly a thin silicon dioxide layer (18) so that said layer maintains the layers of the stack in place, at least on the two opposite lateral sides of the stack; then successively etching laterally and selectively the SiGe layers to form tunnels which are filled with a dielectric substance.

High quality mechanical etching of brittle materials by powder blasting

Abstract: The old technique of sandblasting has recently been developed into a versatile etching technique for brittle materials, capable of producing structures larger than 100 μm. The paper introduces the technique and discusses the mechanism behind the process on the base of theoretical models. The characteristics of patterned etching are illustrated by the evolution of trench-like structures and by the wear of mask patterns, while also some technological aspects will be addressed. With both experimental results and theoretical considerations, it will present the versatility of powder blasting as well-controllable etching process for a wide range of brittle materials.

High temperature tungsten etching process

Abstract: A method of etching a tungsten film, comprising the steps of supporting a semiconductor substrate having a tungsten film thereon on a substrate support in an interior of a plasma etcher, supplying process gas to the interior of the plasma etcher, energizing the process gas into a plasma state, etching the tungsten film by exposing the substrate to the plasma, and heating the substrate to a temperature of at least 100° C. during the etching step. The etching step can include a low temperature main etch below 100° C. followed by a high temperature overetch above 100° C., the process gas including a fluorine containing gas during the main etch and a chlorine containing gas during the overetch. The tungsten film can be located over a dielectric film which serves as a stop layer during the etching step. The tungsten film can be pure tungsten and the dielectric layer can be a silicon oxide film having a thickness of 200 Å or less.

GaN and related materials II

Abstract: 1, Laser Diodes 2. GaN and AlGaN Devices: Field Effect Transistors and Photodetectors 3. Growth and Doping of and Defects in III-Nitrides 4. Structural and Electronic Properties of AlGaN 5. Theory of Laser Gain in Group III-Nitride Quantum Wells 6. Electronic and Optical Properties of Bulk and QW Structure 7. Materials Theory Based Modelling of GaN Devices 8. Erbium Doping of III-V Nitrides 9. Thermodynamic and Electronic Properties of GaN and Related Alloys 10. GaN Device Processing 11. Contacts to GaN 12. Ion Implantation Advances in Group III-Nitride Semiconductors 13. Inductively Coupled Plasma Etching of III-V Nitrides 14. Low Energy Electron Enhanced Etching (LE4) of III-N Materials