Electron Cyclotron Resonance-reactive Ion Etching Research Articles

Microfabrication of Transparent Thermoplastic Resin Plates by Dry Etching

This paper describes the microfabrication of transparent thermoplastic plates, polymethyl-methacrylate, polycarbonate, and cyclic olefin polymer by an electron cyclotron resonance-reactive ion etching (ECR-RIE) system. The system was adopted for the microstructure with smooth surface and high-aspect ratio. The etching was carried out using O2/CF4 plasma. The etching conditions are set at 13.56 MHz high-frequency output of 100 W (self-bias voltage: -430 V--310 V) and the stage temperature of -15°C. We have examined the surface roughness and the optical properties at the range of process pressure 0.05-0.5 Pa. The surface roughness of etched substrates is below 20 nm and the average transmittance is over 98% at the process pressure of 0.05 Pa.

Raman scattering study of GaN nanostructures obtained by bottom-up and top-downapproaches

GaN nanocolumnar structures were grown by plasma-assisted molecular beam epitaxy(PAMBE) and also fabricated by electron cyclotron resonance reactive ion etching(ECR-RIE) of a compact GaN film parallel to the [111] direction of the Si(111) substrates.Scanning electron microscopy shows that the nanocolumns fabricated by PAMBE havea length of about 300–500 nm with diameters ranging from 20 to 150 nm whilenanowhiskers formed by RIE have diameters of 40–80 nm and a height between 1.4 and1.7 µm. A comparative study of the vibrational spectrum (including optical and interfacephonons) of the nanostructures using conventional macro-Raman and micro-Ramanscattering as well as surface-enhanced Raman scattering is presented.

Improved Etched Surface Morphology in Electron Cyclotron Resonance-Reactive Ion Etching of GaN by Cyclic Injection of CH4/H2/Ar and O2 with Constant Ar Flow

Electron cyclotron resonance reactive ion etching (ECR-RIE) conditions for GaN using CH4/H2/Ar are investigated. GaN can be etched even with continuous etching using CH4/H2/Ar when Ar gas of a higher flow rate is introduced, but only rough etched surfaces are obtained. A cyclic injection method using CH4/H2/Ar etching gas and O2 ashing with constant Ar flow is introduced for GaN etching for the first time, and a rather high etch rate and very smooth etched surfaces are successfully obtained. The cyclic injection of CH4/H2 and O2 prevents deposition of carbon polymers by oxygen plasma, and constant Ar flow removes the surface oxidized layer formed during the O2 ashing by Ar+ ion etching. Under the optimized etching condition, an etch rate of 34 nm/min and a good morphology of etched surfaces (rms of less than 1.0 nm) are obtained.

Fabrication and characteristics of lateral type GaN field-emission arrays using metalorganic chemical vapor deposition

Lateral type GaN field-emission diodes were fabricated by metalorganic chemical vapor deposition. In forming the pattern, two kinds of procedures were proposed: a selective etching method with electron cyclotron resonance-reactive ion etching (ECR-RIE) or a simple selective growth utilizing Si3N4 film as the masking layer. The device fabricated using ECR-RIE exhibited electrical characteristics such as a turn-on voltage of 35 V for a 7 μm gap and an emission current of ∼580 nA/10 tips at an anode-to-cathode voltage of 100 V. The field emission characteristics of GaN tips were attributed to the tip structure, low electron affinity and short distance between the cathode and anode tips.

Electron Cyclotron Resonance-Reactive Ion Etching of III-V Semiconductors by Cyclic Injection of CH4/H2/Ar and O2 with Constant Ar Flow

Electron cyclotron resonance-reactive ion etching (ECR-RIE) is very useful for fabricating semiconductor photonic devices and integrated circuits (PICs). The mixture gas of CH4/H2 is used for etching III-V semiconductors, but the carbon polymer film deposited on the surface during the etching process presents some problems. Thus, the polymer film must be ashed off using an O2 plasma. We introduced the cyclic injection of CH4/H2/Ar and O2 to ECR-RIE, and demonstrated that it was very useful for etching of InP. However, compound semiconductors containing Al (e.g., AlGaAs and InAlAs) react with oxygen and an alumina layer is formed, which cannot be etched by CH4/H2 etching. Therefore, we used a new cyclic etching process with constant Ar flow in the chamber to remove this alumina layer by Ar ion etching, and obtained good results for etching rate and surface morphology for the compound semiconductors containing Al. We also proposed a suitable combination of three cyclic etching procedures (continuous etching, cyclic etching without constant Ar flow and cyclic etching with constant Ar flow) for etching the multilayer heterostructure of III-V semiconductors including InP and/or compound semiconductors containing Al.

Low-Damage Indium Phosphide Sidewall Formation by Reactive Ion Etching

We investigated the sidewall damage of InP mesa structures formed by electron-cyclotron-resonance reactive ion etching (ECR-RIE) using CH4/H2. It was found that the reverse current of a p-i-n junction is affected by O2 plasma treatment used for the removal of hydrocarbon deposited during etching. The reverse current was reduced by removing the hydrocarbon, but the excessive O2 plasma treatment led to an extreme increase in the reverse current. Under optimized O2 plasma treatment conditions, the reverse current was reduced to the same level as that of the mesa formed by wet etching. Auger electron spectroscopy (AES) measurements show that phosphorus depletion and oxidization are occurred at the sidewall during the excessive O2 plasma treatment.

Effect of N2 Addition on Aluminum Alloy Etching by Electron Cyclotron Resonance Reactive Ion Etching and Magnetically Enhanced Reactive Ion Etching

Aluminum alloy etching is an important process in ultra-large-scale integration (ULSI) fabrication. We investigated the effect of N2 addition to Cl2+BCl3 gas mixture on aluminum-copper alloy etching by electron cyclotron resonance reactive ion etching (ECR-RIE) and magnetically enhanced reactive ion etching (MERIE). In ECR-RIE, N2 addition was effective in suppressing residues and post-etch corrosion of aluminum alloy interconnects; on the other hand, in MERIE, N2 addition promoted the formation of residues and post-etch corrosion. This difference is probably caused by BClX+ in plasma, because it was found by mass spectral analysis that N2 addition increased the amount of BClX+ in plasma of ECR-RIE, but it decreased that in plasma of MERIE.

Rapid thermal low-pressure metal-organic chemical vapor deposition (RT-LPMOCVD) of semiconductor, dielectric and metal film onto InP and related materials

Abstract Rapidly thermal low-pressure metal-organic chemical vapor deposition (RT-LPMOCVD) was explored as a way to carry out a number of critical steps in the processing of InP-based laser devices, under a vacuum environment. Single-wafer integrated processes (SWIP) employing a multi-chamber cluster tool are suggested as an alternative approach to sequential hybrid batch processing. This work includes demonstrations of the processes for each of the required modules of the cluster. The following processes were realized by means of the RT-LPMOCVD technique: 1. 1. Wafer cleaning using tertiarybutylphosphine (TBP). The InP wafers were annealed at a low protective ambient pressure. Wafer surfaces were degradation-free after being heat-treated at temperatures up to 750 °C for times as long as 30 s under a TBP ambient. 2. 2. III–V semiconductor film deposition. InP and InGaAs layers, undoped and Zn-doped, with low impurity backgrounds were grown using tertiarybutylphosphine (TBP), tertiarybutylarsine (TBA), trimethylindium (TMIn), trimethylgallium (TMGa), and dimethylzinc (DMZn). 3. 3. Deposition of SiO 2 spacer layers onto epitaxially grown InGaAs and InP layers. The SiO 2 films were deposited using a gas mixture of O 2 and 2% diluted SiH 4 in Ar. 4. 4. Reactive ion etching (RIE) of the InP-based material in an electron cyclotron resonance-reactive ion etching (ECR-RIE) chamber. A stainless-steel mask (25 μm thick) with openings (500 μm long and 50–250 μm wide) was aligned on top of the wafer, and RIE of SiO 2 layers was performed through the mask openings. 5. 5. Cleaning of the semiconductor contacting stripes by heating the wafer at 500 °C under a TBP ambient. 6. 6. Metallization of TiN x and W films to produce ohmic contacts and barrier layers. The American Cyanamid tetrakis (dimethylamido) titanium (DMATi) Cypure TM product was used as the TiN x precursor, which was reduced with NH 3 . The W films were deposited using a W 6 source reduced by H 2 .

Proposal of Trench-Oxide Metal-Oxide-Semiconductor Structure and Computer Simulation of Silicon Quantum-Wire Characteristics

We propose “trench-oxide metal-oxide-semiconductor (MOS)” structures as a novel formation method of silicon-based low-dimensional quantum structures, which are considered to be basic elements of future ultrahigh-speed and ultralarge-scale integrated devices. In this method, the applied gate voltage forms the potential well confined in an additional direction defined by ultrafine “trenches” on the oxide layer of the MOS structure. We characterize “trench-oxide MOS” quantum wire structures by two-dimensional numerical calculation of the shape of the potential well, the subband energy levels and the electron density, and investigate the possibility of the experimental observation of quantized density of states peculiar to quantum wires, by measuring capacitance-gate voltage (C-V) characteristics of “trench-oxide MOS capacitors.” We also have successfully fabricated “trench-oxide MOS” quantum wires with the width of 16 nm using electron beam (EB) lithography and electron cyclotron resonance reactive ion etching (ECR-RIE).