Showing papers on "Isotropic etching published in 1981"

The design of plasma etchants

Abstract: Theory and practice of plasma etching are critically reviewed. Some unifying principles are extended to explain a large body of experimental data, encompassing more than 20 substrate materials in dozens of etchant gas mixtures. These basic concepts can be used to select new etchants and plasma etching parameters.

Chemical Etching Characteristics of ( 001 ) InP

Abstract: The chemical etching characteristics of are studied through an mask in the solutions of various etching systems: (i) , (ii) , (iii) , (iv) , and (v) . The etched depth is evaluated by using a calibrated optical microscope. The etching profiles are examined by cleaving the wafer in orthogonal directions along the (110) and (10) planes. Various etching profiles, such as V‐shaped, reverse mesashaped ones, and nearly vertical walls, are formed by stripes being etched on the (001) planes. The indexes of the etch‐revealed planes are identified by making a comparison with the calculated angle between the (001) surface and etch‐side plane. The utility of these etching solutions is also discussed for a variety of device applications.

Chemical etching and cleaning procedures for Si, Ge, and some III‐V compound semiconductors

Abstract: Chemical etching and cleaning procedures that produce the most abrupt dielectric discontinuities between bulk and ambient (cleanest and/or smoothest surfaces) are determined by ellipsometry for single crystals of Si, Ge, and some III‐V compounds. Differences among high‐symmetry orientations for Si and Ge indicate that preferential etching may be a factor in minimizing the amount of interface material left at a surface.

A novel anisotropic dry etching technique

Abstract: We have developed a dry etching technique in which the chemically reactive species and the energetic ions are independently controlled. This technique, which we call ion beam assisted etching (IBAE), is accomplished by impinging a chemically reactive gas from a jet and an ion beam from a Kaufman ion source upon the sample. It is based upon the work of Coburn et al., 1 and differs fundamentally from reactive ion etching (RIE), which relies upon a plasma to produce both the chemically active species and the energic ions. In IBAE the partial pressure of the reactive gas can be as high as several Pa (tens of microns) at the sample surface while the chamber pressure can easily be maintained at about 1×10−2 Pa (10−4 Torr). Although a variety of reactive gases and sample materials have been characterized, the presentation will concentrate on using Cl2 as a reactive gas and an argon ion beam. The anisotropic character of this etching technique has been found to depend on the angles that the gas jet and the ion be...

Apparatus and method for plasma-assisted etching of wafers

Abstract: In a plasma-assisted etching apparatus and method designed to pattern silicon dioxide in a plasma derived from a mixture of trifluoromethane and ammonia, surfaces in the reaction chamber are coated with a layer of silicon. Contamination of wafers during the etching process is thereby substantially reduced. In practice, this leads to a significant increase in the yield of acceptable chips per wafer.

SF 6, a Preferable Etchant for Plasma Etching Silicon

Abstract: is a far more selective etchant for silicon than when excited to a plasma discharge. This applies to good advantage in parallel plate reactors where under given conditions of rf power and pressure the etch ratio of silicon to is 30:1 but with only 7:1. In contrast to the deposition of carbon in a process sulfur has not been found on a silicon surface etched in . The selectivity of an etching process cannot be shifted sufficiently in favor of by adding hydrogen, it can also not be increased much in favor of silicon by adding oxygen. The reaction product is . No other silicon compound than appeared in the mass spectrum. 1% in argon achieves etch rates of more than 100 nm/min with moderate rf energy. is also a useful etchant for with etch rates of 100 nm/min.

Plasma etching of polyimide

Abstract: An improvement in the formation of multilayer metallization systems wherein vias are formed in a dielectric insulating layer of polyimide which overlies a layer of metal such as aluminum. In accordance with the invention, the residual film remaining after oxygen plasma etching of the polyimide is efficiently removed by a second plasma etching utilizing a mixture of argon and hydrogen.

Characteristics of submicron pores obtained by chemical etching of nuclear tracks in polycarbonate films

Abstract: Calibrated pores in the range 102–2×103 A have been obtained by chemical etching of polycarbonate thin films irradiated with high energy krypton ions (500 MeV, Kr25+). Both the amorphous and the crystalline forms of polycarbonate (Makrofol, Bayer), further designated by their respective trade names N and KG, have been investigated up to thicknesses of 60 μm, close to the theoretical ion range of 77 μm. From conductivity studies, three different domains have been separated around the ion track: A highly damaged core of radius ?50 A with a fast etching rate vT ≊104 A/min, an intermediate zone of radius ?500 A with an etching rate vI = 0.9 A/min, an outer region with an etching rate equal to that of the undamaged material, vG = 0.47 A/min. These observations are compatible with the delta ray model for track formation in plastic materials. Scanning electron microscope investigations have revealed that the pores formed in the N material are straight cylinders with a narrow distribution of the pore entrance dia...

Surface Changes during A.C. Etching of Aluminum

Abstract: Electrochemical etching of Al with alternating current produces a high density of cubic etch pits covered with a film of oxide or hydroxide Micrographs of the metal and film structures are presented and a model is proposed to explain the observations Calculations demonstrate the feasibility of film deposition from acid solution when a high cathodic current density is applied A critical feature is that the high aluminum salt concentration near the metal surface hinders proton mobility

Two step plasma etching

Abstract: A method of etching a variable thickness material on a substrate through an opening or openings is disclosed. The method includes a first etch step in which the material is isotropically etched until the substrate material is first exposed defining a first end point. Thereafter, a second anisotropic etch is performed until all of the remaining material at the opening or openings is removed. Preferably the etching is by dry plasma etching and the first end point is detected by monitoring the change in concentration of a reactive species. The change is sharply defined by taking a second derivative of the curve of the change in intensity of the peak of the sensed species.

Reactive ion etching for VLSI

Abstract: Reactive Ion Etching (RIE) is a dry etching technique that is used to etch 1-µm and submicrometer patterns into films of silicon and silicon compounds. RIE is suitable for VLSI applications because etching is anisotropic and proceeds via chemical reactions with the substrate. Anisotropic etching allows faithful reproduction of resist patterns into the films that make up a device, and chemical etching allows development of selective etching by manipulating the composition of the plasma. The RIE reactor is described and examples of its use to fabricate 1-µm MOSFET's are given. Concerns arising from the presence of a voltage between the substrates and the plasma, radiation damage of SiO 2 and contamination of silicon, are discussed.

Manufacture of semiconductor device

Abstract: PURPOSE:To obtain a high-density memory easy to be fined by a method wherein an (n) layer and a (p) layer in a capacitance section are formed by the self-alignment of a gate electrode, mask alignment is omitted, a capacitance electrode is also shaped to the upper section of the gate electrode through SiO2 and mask re-alignment is omitted. CONSTITUTION:The surface of a p-type Si substrate 1 is isolated by an oxide film 2, a gate oxide film 3 and a poly Si gate electrode 4 are shaped, and an n layer 5 is formed through the implantation of P ions. The layer 5 is coated with CVDSiO2 6, a side wall 6 is attached on the electrode 4 through isotropic etching and an n layer 7 is shaped through the implantation of As ions. B is implanted in depth deeper than P and As by using a resist mask. A high melting-point metal 9 is sputtered and annealed, thus forming an silicide layer 10 on the surfaces of the substrate 1 and the electrode 4. The metal 9 not reacted is removed, and the surfaces are coated with a thermal oxide film 11. A capacitance electrode 12 consisting of poly Si is annexed, thus completing a semiconductor device. Since the margin of mask alignment is unnecessitated, the semiconductor device can be fined, and not only the resistance of the surfaces of the electrode 4 and the diffusion layers 5, 7 is lowered by a metallic silicide and the working speed of the device is increased but also photo-engraving processes are decreased, thus reducing cost.

Self-aligned pole tips

Abstract: A method is disclosed for precisely aligning the pole tips of a thin film magnetic head. Two separate metallic layers, such as Permalloy (Ni-Fe alloy) are separated by a layer of insulating material such as silicon dioxide or AL 2 O 3 which will serve as the insulative spacer of the final magnetic head. A photo-resist is applied to the surface of the top metallic layer in an imagewise configuration to establish the shape of the top pole. The top pole is then etched and the photo-resist removed. The top electrode is then encapsulated with a protective metal and is used as a mask during the chemical etching of the insulative layer, the bottom electrode being used as an etch stop. This integral structure is then used as a mask during the chemical etching of the bottom electrode, resulting in pole tips which are precisely aligned.

Method for patterning films using reactive ion etching thereof

Abstract: In the patterning of an organic layer on a VLSI wafer by means of reactive oxygen (or other) ion anisotropic etching, build-ups of oxides (or other compounds) on the sidewalls of apertures formed in the organic layer are removed prior to etching the material, typically aluminum, of the VLSI wafer located at the bottom of these apertures, using the patterned organic layer as an etch mask.

Manufacture of semiconductor device

Abstract: PURPOSE:To form the angle-cut contact hole in a sectional shape by a method wherein an isotropic etching is performed on the substance film provided on a semiconductor substrate and then an anisotripic etching is performed. CONSTITUTION:A thermal oxide film 3 and a CVDPSG film 4 are successively formed on the Si substrate having a diffusion layer on the surface, and a contact hole is formed by firstly performing an isotropic etching and then performing an anisotropic etching using a photoresist film 5 as a mask. Through these procedures, the angle-cut contact hole in the sectional shape is formed and the breaking of wire on a wiring layer can be prevented. Further, said section can be made more smoothly by performing a heat treatment and a glass frow on the PSG film 4.

Nb/Nb oxide/Pb-alloy Josephson tunnel junctions

Abstract: A procedure is described for fabricating thin film Nb/Nb oxide/Pb-alloy Josephson tunnel junctions that satisfies the principal requirements for integrated circuit design and fabrication. A deposited Nb film, evaporated from an e-gun heated source, was patterned by chemical etching to form a base electrode. A junction was completed by plasma etching and plasma oxidizing the Nb junction area to form a tunnel barrier and by depositing a Pb alloy counterelectrode. Josephson tunnel junctions with Nb/Nb oxide/Pb-Au-In structures were prepared with low excess subgap currents in the current-voltage (I-V) curve and with reproducible and stable I-V characteristics. Variations in junction current density from run-run were ± 15%. Seven 3-junction interferomeeters out of a population of 50,000 were shorted (99.99% yield) for causes not immediately attributable to photoresist-related defects. No changes in Josephson current were detected after thermal cycling 17,000 interferometers 1,800 × between room temperature and 4.2°K, after storing them for 2 years at 5°C, or after annealing 5,000 interferometers for 4.5 hours at 70°C.

Metal dissolution process using H2 O2 --H2 SO4 etchant

Abstract: An improved process for dissolution of metals by etching, and particularly the etching of copper in printed circuit board processing or the like, using an aqueous H 2 O 2 --H 2 SO 4 etching solution, in which the concentration of H 2 SO 4 in the etching solution is allowed to decrease during use of the etching solution from an initial, relatively high level at the time the etching solution is put into use, to a final, relatively low level. When a predetermined concentration of dissolved etched metal exists in the etching solution, the etching solution is removed from use, H 2 SO 4 is added to increase the concentration of H 2 SO 4 in the etching solution to approximately the initial, relatively high level, and the metal is precipitated out of the etching solution.

Dry etching method and device therefor

Abstract: A dry etching method and device involve induction of a magnetic field having field lines perpendicular to an electric field by magnets which are arranged in the vicinity of a cathode within a reaction chamber, on the surface of the cathode being placed a sample to be etched by a plasma of an etchant gas.

Plasma etching electrode

Abstract: A planar plasma etcher (10) wherein a plurality of projections (36, 136, 236) extend from one electrode (18), with each projection aligned with a wafer (22) placed on the second electrode (20) to provide uniform etching across the surface of each wafer. The surface of the projection facing the wafer can take several forms depending on etching conditions, including convex, concave or frusto-conical.

Process and gas mixture for etching aluminum

Abstract: Process and gas mixture for etching aluminum in a plasma environment in a planar reactor. The gas mixture comprises a primary etching gas and a secondary gas which controls the anisotropic character of the etch. A stable uniform plasma is generated at relatively high pressure and power levels, and this provides substantially faster removal of aluminum than has heretofore been possible in planar reactors.

Semiconductor device design and process

Abstract: A method for fabricating a gate-source structure for a recessed-gate static induction transistor. Source impurities are implanted prior to forming the recessed gates. The recessed gates are formed by a first isotropic etching step and a second anisotropic etching step which results in a unique overhanging protective layer used to protect the walls of the grooves during implantation of gate impurities in the bottom of the grooves. Implantations are driven and activated to form gate and source regions, the protective layer is removed and metal deposited to form electrodes. The procedure minimizes the required number of masking steps and associated mask registration problems.

XPS study of interface formation of CVD SiO2 on InSb

Abstract: The interfacial chemistry of CVD SiO2 films deposited on thin native oxides grown on InSb substrates is examined using X-ray photoemission spectroscopy (XPS) and a relatively benign chemical etching technique for depth profiling. An intensity analysis of XPS spectra is used to derive the compositional structure of the interfaces obtained in the SiO2/native oxide/InSb system. Peak positions in these spectra are used to follow the change in substrate surface potential during the etch sequence, and to establish the chemical nature of the species formed during deposition and subsequent processing. Reaction of the substrate with oxygen resulted in an In-rich native oxide and 1-2 monolayers of excess elemental Sb at the native-oxide/substrate interface, incompletely oxidized silane reduced the native oxide, leaving less than 1 monolayer of elemental In at the SiO2/native oxide interface. Etch removal of this thin In-rich layer leads to a change in the substrate surface potential of 0.06 eV, corresponding to a net increase in positive charge. The results are consistent with simple thermodynamic considerations; they are also compared to previously reported studies of deposited dielectrics on III-V compound semiconductors.

Fabrication of x‐ray masks using anisotropic etching of (110) Si and shadowing techniques

Abstract: We describe a process for producing x‐ray masks of grating patterns with extremely smooth line edges. The technique developed by Flanders, in which a square‐wave profile relief grating in polyimide is obliquely shadowed with an x‐ray absorber, is followed, except that the original square‐wave structure is produced in (110) silicon by anisotropic chemical etching rather than in SiO2 by reactive ion etching. In this way, significant improvements in edge acuity are achieved because relief grating sidewalls are defined by atomic (111) planes. Holographic lithography is used to expose grating patterns in AZ 1350 over a thin Si3N4 layer on the (110) Si. The Si3N4 is patterned by reactive ion etching and serves as the mask for anisotropically etching the square‐wave‐profile grooves. At the proper crystallographic orientation the groove sidewalls are defined by (111) planes, and groove bottoms are approximately flat. The structure in Si is then transferred to polyimide which is obliquely shadowed and forms the x‐...

Crystallographic facets chemically etched in GaInAsP/InP for integrated optics

Abstract: Vertical crystallographic (011) planes were exposed on (100) GaInAsP/InP double heterostructures (DH) by a newly developed chemical etchant and method. This method provides optically flat, mirror quality facets reproducibly and could be very attractive in integrated optics and optoelectronic devices.

Non-Destructive Analysis of the Si-SiO2Interface by Electron Energy Loss Spectroscopy Study

Abstract: Thin SiO2 (up to ~60 A thick) grown thermally on crystal Si (111) and (100) substrates was examined without any destructive treatments such as ion sputtering and chemical etching by electron energy loss spectroscopy (ELS) technique. The non-destructive ELS measurements were based on an employment of tunable escape length (~10 to several tens A) of probing electrons with different energies of 0.2–2.3 keV. With incident energies above critical ones dependent on oxide thickness, the loss spectra indicated a new feature at the transition energy of ~7.7 eV, which was identified to be associated with the Si–SiO2 interface, probably interfacial plasmons of the Si–SiO2 couple. The possible presence of roughness or undulation in the Si–SiO2 interface, which was considered to be a sharp one in the chemical structure, was discussed.

Crystallographic polarity and chemical etching of CdxHg1−xTe

Abstract: The absolute crystallographic polarity of CdxHg1−xTe crystals (x?0.2) has been determined using the anomalous scattering of x rays and correlated with the chemical etching characteristics. It is shown that Cr Kα radiation adequately distinguishes 333 and 333 reflections, and that the reflected intensities agree closely with theoretical calculations. Using a range of chemical etchants it is reported that dislocation etch pits are revealed on the (111) or A face, i.e., the face terminating with triply bonded Cd (Hg) atoms or singly bonded Te atoms, and not on the (111) or B face.

Reactive ion etching for submicron structures

Abstract: The etch resistance of PMMA was measured under various reactive ion etching conditions and compared with that of silicon dioxide, silicon and Shipley AZ 1350 resist. The resulting profiles transferred into the substrates masked with PMMA were also studied under various reactive ion etching conditions. This study showed that PMMA can be used as a masking resist for etching silicon dioxide using fluorine‐deficient etch gases. Linewidths with dimensions of 0.1 μm have been obtained in silicon dioxide with usable selectivity between PMMA and silicon dioxide.