Plasma Chemical Etching Research Articles

Изготовление сверхпроводниковых туннельных структур с использованием электронно-лучевой литографии

The technology for manufacturing submicron Nb - AlN - NbN tunnel junctions using electron beam lithography has been developed and optimized. Investigations have been carried out to select the exposure dose, development time, and plasma-chemical etching parameters to obtain the high quality of junctions (the ratio of the resistances below and above the gap Rj/Rn). The use of a negative resist ma-N 2400 with lower sensitivity and better contrast in comparison with a negative resist UVN 2300-0.5 has improved the reproducibility of the structure fabrication process. The submicron (area from 2.0 to 0.2 µm2) tunnel junctions Nb - AlN - NbN with high current density and quality parameter Rj / Rn> 15 were fabricated. The spread of parameters of submicron tunnel structures across the substrate and the reproducibility of the cycle-to-cycle process of fabrication of tunnel structures has been experimentally measured.

Исследование методов текстурирования светодиодов на основе гетероструктур AlGaAs/GaAs

Investigations of methods for texturing the light-emitting surface of IR light-emitting diodes (LEDs) (wavelength 850 nm) based on AlGaAs/GaAs heterostructures with Bragg reflectors have been carried out. Developed were methods of liquid and plasma-chemical etching of solid solution for creating peaks (pyramids) of different form, 0.2–1.5 µm height. Estimation of the effect of texturing methods and also configuration of peaks on the light-emitting diode electroluminescence intensity has been performed. The increase of the electroluminescence intensity by 25% has been achieved.

Deep Etching of LiNbO3 Using Inductively Coupled Plasma in SF6-Based Gas Mixture

This work is an extensive study of the plasma chemical etching (PCE) process of single-crystalline lithium niobate (LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) in the SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> /O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> based inductively coupled plasma (ICP). The influence of the main technological parameters of the LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PCE process, including the distance between the sample and the lower edge of the discharge chamber, as well as the temperature of the substrate holder on the etching process rate, has been studied. It was shown that changing the temperature of the substrate holder in the range from 100 to 200°C leads to a gradual rise of the etching rate from 127 to 282 nm/min. A further increase in the temperature to 250°C results in a sharp increase in the etching rate to 711 nm/min. The maximum achieved etching rate in experimental series which were aimed at determining the dependence of the LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> etching rate on the temperature of the substrate holder was 812 nm/min at a substrate holder temperature of 325 °C. With the help of X-ray photoelectron spectroscopy (XPS) technique was found and shown that during the etching process in fluorinated plasma the nonvolatile LiF compound is formed on the surface of the treated LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> . On the basis of the obtained results, the optimal process of deep (>80 μm) LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PCE was developed, with an etched wall inclination angle of 110°, with selectivity ratio to Cr mask of 20, and an etching rate of about 300 nm/min. [2020-0317] Index Terms-Heating, inductively coupled plasma, plasma etching, lithium niobate, SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> /O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma.

Self-Organization of Ge(Si) Nanoisland Groups on Pit-Patterned Si(100) Substrates

Space-arranged arrays of pits on Si(001) substrates were prepared using electron-beam lithography and plasma chemical etching. The positions of pits were arrange to the square and hexagonal lattices with a varying spacing. It was shown that the location of three-dimensional (3D) Ge nanoislands subsequently grown on the pit-patterned Si substrates depends on spacing for the both lattice types. In the case of the small spacing Ge nanoislands are located mainly inside the pits, while for the larger inter-pit distance the groups of Ge nanoislands at the pit periphery is also observed. This effect is interpreted in terms of critical volume for the 3D island nucleation which is achieved at the pit periphery with the increase of Ge amount deposited per pit. The effect of nanoisland growth, first inside the pits, then at their periphery was reproduced by Monte Carlo simulations of Ge growth on the pit-patterned Si substrates.

Плазмохимическое травление тонких пленок серебра для приложений плазмоники индуктивно-связанной аргоновой плазмой

The study focuses on the processes of plasma-chemical etching of silver films for the manufacture of photonic elements --- nanoscale light sources, and examines the theoretical foundations of etching processes and the process of plasma formation in plasma-chemical etching facilities. We assessed the introduced technology when forming topological elements in thin films of silver metal, and identified key problems, such as redeposition and non-volatility of the material. The paper presents the results of simulating the etching process for several critical submicron sizes, and, based on the simulation results, shows the dependences of the etching rates on the power of the plasma sources. The focus is on the formation of holes to create a nanoscale light source. Both positive and negative properties of the plasma-chemical etching method using a source of inductive-coupled plasma are considered, and the features of technological facilities used for these processes are outlined. The process of formation of nanoelements in a silver film and the effect of redeposition of material particles as a result of ion sputtering are considered. We propose a two-stage etching process, which makes it possible to form a vertical profile of the walls of the manufactured elements and to avoid the effect of redeposition. We also give recommendations for the processes of etching through an electron-beam resist in facilities with an inductive-coupled plasma source. By optimizing the thicknesses of the resistive mask and plasma sources, we obtained the results of etching nanoscale elements with preservation of geometric shapes

Плазмохимическое и жидкостное травление в постростовой технологии каскадных солнечных элементов на основе гетероструктуры GaInP/GaInAs/Ge

Investigation and development of a separating mesa-structure creating technology for fabricating multi-junction solar cells based on the GaInP/GaInAs/Ge heterostructure has been carried out. Studied were methods of etching of heterostructure layers: liquid chemical etching in the etchants based on HBr, H2O2, K2Cr2O7 and plasma-chemical etching in the stream of operating gas BCl3. The comparative analysis of etching methods was studied. The protective masks based on photoresist layer and TiOx/SiO2 were developed. Multi-junction solar cells with low parameters of leakage current less than 10-7 A at voltage 0,5-1 V were created.

Formation of carbon nanoscale elements of vacuum microelectronics by plasma treatment of SiC

The use of focused ion beams and atomic plasma chemical etching for forming an array of field emission structures on surface of SiC substrates is considered. SF6 was used as the fluorine-containing gas. Topology of formed elements was monitored using scanning electron microscopy method at Nova NanoLab 600. Dependences of geometric parameters of formed structures (topology of tip and its depth) on emission current were determined. Dependence of change in applied voltage and generated electric field of used to study probe on emission current density is also considered.

OES diagnostic of SF6/Ar gas mixture of ICP discharges for LiNbO3 etching

The results of a study of the influence of technological parameters of the process of plasma chemical etching in inductively coupled plasma on the emission spectra of fluorine and argon atoms are presented. The effects of inductively coupled plasma RF power, operating pressure and bias voltage were studied for 6 different sulfur hexafluoride argon (SF6/Ar) gas mixtures: SF6 (1.5 sccm)/Ar (9.2 sccm), SF6 (7.8 sccm)/Ar (10.8 sccm), SF6 (4.7 sccm)/Ar (6.0 sccm), SF6 (7.0 sccm)/Ar (4.9 sccm), SF6 (11.7 sccm)/Ar (5.4 sccm), SF6 (9.4 sccm)/Ar (3.3 sccm). It is shown that a decrease in the operating pressure and an increase in the RF power of the inductively coupled plasma leads to an increase in the relative intensity of both argon and fluorine lines. Variations in the bias voltage have no significant effect on the emission intensity of the spectral lines of Ar and F.

Features of the Vapor-Phase Epitaxy of GaAs on Nonplanar Substrates

The features of the surface shape of GaAs epitaxial layers grown on grooves several micrometers wide with vertical walls and an aspect ratio close to unity are investigated. The grooves are formed on the surface of a GaAs wafer in a plasma-chemical etching installation and overgrown by organometallic vapor-phase epitaxy under reduced pressure in a reactor.

Investigation of the Effect of Atomic Composition on the Plasma-Chemical Etching Rate of Silicon Nitride in High-Power Transistors Based on an AlGaN/GaN Heterojunction

The effect of atomic composition on the rate of the plasma-chemical etching of silicon nitride in high-power transistors based on an AlGaN/GaN heterojunction is studied. It is shown how the subsequent process of its plasma-chemical etching depends on the configuration of the incorporation of hydrogen impurity atoms into the molecular structure of silicon nitride deposited in the plasma. The dependence of the etching rate on the process parameters (the working pressure in the chamber, the plasma-generator power, the working-gas flows, and the deposition temperature) is investigated. It is shown that the etching rate of the HxSirNzHy film is independent directly on the hydrogen content but significantly depends on the ratio of [Si–H]/[N–H] bonds. The etching rate of HxSirNzHy in high-density plasma at low powers is much less dependent on the configuration of hydrogen bonds than the etching rate of this dielectric in a buffer etchant.

Method for Manufacturing Silicon X-Ray Masks Via Plasma Chemical Etching

A simple method for manufacturing silicon masks for deep X-ray lithography, conducted with the application of exposure radiation of the spectral range (0.5–7 A), is described. This method is based on planar silicon technology, which is widely used in the production of semiconductor devices. A significant difference between this method and previously known analogues is that it does not apply the creation of a stop layer by doping during formation of the support membrane of the mask. As the initial blank, a standard (100) oriented silicon wafer is used. The silicon support membrane of the mask is formed in the final stage of its manufacture by plasma-chemical etching of the rear-side of the wafer to a predetermined depth. The thus obtained X-ray masks on a silicon wafer are characterized by relative ease of manufacture, radiation and chemical resistance, geometric stability, and relatively high levels of mechanical strength and X-ray transparency of the support membrane, depending on its thickness, which can be manufactured with good accuracy and within a fairly wide range of ~2.5–50 μm, depending on the purpose of the mask.

Dry etching of silicon carbide in ICP with high anisotropy and etching rate

A detailed study of the influence of technological parameters of the plasma chemical etching process in inductively coupled plasma on the etching rate of single-crystal silicon carbide is presented. The physicochemical substantiation of experimentally revealed patterns is given. The optimal gas mixture was determined in terms of the etching rate of SiC. It was experimentally established that the dependence of the etching rate of silicon carbide on the percentage of oxygen in the total gas mixture is non-linear. Thus, with an increase in the percentage of O2 up to 23%, the etching rate of SiC gradually increases to 560 nm/min, a further increase in the percentage of O2 leads to a sharp decrease in the etching rate of SiC up to 160 nm/min at an oxygen content of 31%. The effect of the distance between the sample and the plasma generation zone on the etching rate of SiC was studied. It was shown that the greatest increase in speed is caused by an increase in the bias voltage, so at Ubias = - 50 V the etching rate is 300 nm/min, and at Ubias = - 150 V the value of the etching rate is 840 nm/min. The optimal parameters of the plasma-chemical etching process were selected for high-speed directional etching of single-crystal silicon carbide substrates.

Research of Constructive and Technological Methods for Forming a Silicon Disk Resonator with Whispering Gallery Modes

This article presents the results of a computer simulation of whispering gallery modes in the structure of a silicon disk resonator with a wedge-shaped profile made on a silicon-on-isolator base (SOI). The rationale for the choice of silicon as a material for its manufacturing is given. The results of the study of the influence of the wedge angle on the whispering gallery mode parameters (WGM) are presented. The optimum wedge angle of a silicon disk resonator is determined, which ensures the minimum loss and maximum mode stability. The technological aspects of plasma-chemical etching processes for forming a wedge-shaped profile of the edge of a silicon disk resonator are studied.

Influence of the Finite-Size Effect on the Cluster Ion Emission of Silicon Nanostructures

The finite-size effect increasing the emission of polyatomic cluster ions from silicon nanostructures as compared to a macroscopic sample has been studied. This study has been performed for the first time in periodic structures with 10- and 50-nm-wide combs fabricated by electron beam lithography with subsequent plasma chemical etching. It has been shown that the yield of polyatomic cluster ions from structures with the comb whose effective width is comparable with the projective range of a bombarding bismuth ion in silicon is much higher than the yield from macroscopic samples, e.g., by more than a factor of 5 for 28Si10− (m/z = 280). This effect has been explained by a partial limitation of dissipation channels for the energy released by the bombarding ion in the volume of the structure, which stimulates a more efficient development of nonlinear collision cascades in such a volume and, as a result, increases the yield of polyatomic cluster ions.

Hole Formation in a Diamond Substrate of Hybrid-Monolithic Integral SHF Schemes

In this paper, we study the technological process of separating a heteroplate from a polycrystalline diamond film (PDF-Si), separating a whole plate from sacrificial silicon. The hole formation in a diamond substrate from PDF via laser milling and plasma-chemical etching is studied. Plasma-chemical etching provided batch hole fabrication based on planar technology and precision lithography. The technological modes of hole etching through an aluminum mask via reactive ion etching with an inductively coupled plasma source (RIE-ICP) were optimized. The hole etching rate in the PDF was ~ 1.1 μm/min. A mathematical model of the technological process is developed. Etching is shown to occur mainly in oxygen. The technological process is adapted for the plasma-chemical etching setup “Plasma TM5”. The possibility of etching in a PDF holes 100 μm in diameter and more than 300 μm deep was studied. The etching rate was shown to depend on the hole depth and is nonlinear in nature, with etching of the hole walls and the aluminum mask.

ICP etching of SiC with low surface roughness

Silicon Carbide (SiC) has a wide range of applications in various fields, such as high-strength composite materials, materials for abrasive applications, and etc., but the most interesting is a single-crystal silicon carbide, 3C-SiC, 4H-SiC, 6H-SiC, which is widely used in the electronics industry. Authors investigated the process of plasma-chemical etching of the SiC (6H-SiC) in the relatively high temperatures range of the substrate holder (100 – 250 °C) in thespecifically designed state-of-art plasma-chemical etching system based on the inductively coupled plasma source. The system allows to independently vary the energy and density of ionswhichare reacting with the surface of the processed material. Also, the temperature of the substrate holder can be varied and precisely controlled in the temperature range from 20 to 400 °C in order to get smooth surface of the etched structures (Rms < 5 nm) in the SF6/O2 gases mixture. As a result of the study, the dependence of the mean square surface roughness of etched structures on the temperature of the substrate holder was determined. Was shown, that the substrate holder temperature increase leads to the reduction of the etched structures surface roughness. The physicochemical substantiation of the revealed dependence is given. The authors managed to achieve a root square roughness of the surfaces of the etched structures about 3.3 nm when the initial roughness of SiC substrates was about 9 nm.

Исследование влияния атомарного состава на скорость плазмохимического травления нитрида кремния в силовых транзисторах на основе AlGaN/GaN-гетероперехода

The effect of atomic composition on the rate of plasma chemical etching of silicon nitride in power transistors based on an AlGaN / GaN heterojunction is studied. It is shown how the subsequent process of its plasma-chemical etching depends on the configuration of the incorporation of hydrogen impurity atoms into the molecular structure of the silicon nitride deposited in the plasma. The dependence of the etching rate on the parameters of the process (the working pressure in the chamber, the power of the plasma generator, the flow of working gases, the deposition temperature) is investigated. It was shown that the etching rate of the HxSirNzHy film does not depend directly on the hydrogen content, but significantly depends on the ratio of [Si-H] / [N-H] bonds. The etching rate of HxSirNzHy in a high-density plasma at low powers is much less dependent on the configuration of hydrogen bonds than the etching rate of this dielectric in a buffer etchant.

Influence of operation parameters on BOSCH-process technological characteristics

Authors investigated direct plasmachemical etching of silicon with Bosch-process using installation for inductively coupled plasma (PLATRAN-100) in gas area consist of SF6 and CHF3 gases in etching and deposition steps respectively. Defined correlations of etching rate, selectivity Si/photoresist, anisotropy, etch uniformity and sidewall angle on flow rate of polymerizing gas and electrical bias on deposition step. It is shown that increasing of CHF3 flow rate leads to higher etch selectivity Si/photoresist, anisotropy and uniformity of silicon but increase etching rate and sidewall angle. Also there was demonstrated that increasing of electrical bias on deposition step leads to higher silicon etching rate, uniformity and sidewall angle but at the same time decrease anisotropy and selectivity Si/photoresist. Authors reached etch selectivity Si/photoresist about 38 with etch uniformity 99.3% and depth about 18 mkm. The highest speed of silicon etch was 3.12 μm/min with uniformaty 99.7% and sidewall angle 89.6 °.

Особенности газофазной эпитаксии GaAs на непланарных подложках

Abstract The features of the surface shape of GaAs epitaxial layers grown on grooves several micrometers wide with vertical walls and an aspect ratio close to unity are investigated. The grooves are formed on the surface of a GaAs wafer in a plasma-chemical etching installation and overgrown by organometallic vapor-phase epitaxy under reduced pressure in a reactor.

Improved oxidation resistance of CoNiCrAlTaHfY/Co coating on C/C composites by vapor phase surface alloying

Abstract