Haruhisa Kinoshita

PbTe‐Pb1−xSnxTe superlattices prepared by a hot wall technique

The PbTe‐Pb0.8Sn0.2Te superlattices were made by the hot wall technique on BaF2 substrates. Two superlattices with the period thickness of 100 and 200 A were analyzed by sputtering‐Auger electron spectroscopy and good results were obtained. The interdiffusions of Pb and Sn across the junction were also investigated and the diffusion coefficients of Pb and Sn at 300 °C were found to be 1.8 and 2.9×10−17 cm2/sec, respectively.

(p/n) PbTe multiple‐layer films prepared by a hot wall technique

The PbTe multiple‐layer structures with alternating types of conductivity (p/n) were made by the hot wall technique. The net carrier density of multiple‐layer films (obtained by Hall‐effect measurements) decreased by an order of magnitude compared to singly doped films. These multiple‐layer films indicated sensitive photoconduction and their structures were confirmed by I‐V and C‐V measurements.

Preparation of electrically conductive diamond-like carbon films using i-C4H10/N2 supermagnetron plasma

Electrically conductive diamond-like carbon (DLC) films were deposited by supermagnetron plasma chemical vapor deposition. The deposition was made on Si and glass wafers using mixed isobutane (i-C4H10) and N2 gases. The physical properties of deposited film were measured and analyzed. Fourier transform infrared spectroscopy measurements revealed that the absorption due to N–H, C–N, and C≡N bonds increased with increases in N2 gas concentration. The increase in electrical conductivity could be attributed to C–N and C≡N bond creation in the DLC films. The lowest resistivity, 0.17 Ω cm, was achieved at an N2 concentration of 70%, gas pressure of 50 mTorr, lower electrode temperature of 160 °C, and rf powers of 1 kW/1 kW. The lowest resistivity film was 1750 kg/mm2 hard, harder than glass (1340 kg/mm2). Raman spectroscopy measurements revealed two peak D and G bands, and the D band was more intense than the G band. The optical band gap decreased with increases in the N2 concentration. Hall measurements showed...

Intermittent chemical vapor deposition of thick electrically conductive diamond-like amorphous carbon films using i-C4H10/N2 supermagnetron plasma

Electrically conductive diamond-like amorphous carbon (DAC) films with nitrogen (DAC:N) were deposited on Si and SiO2 wafers using the i-C4H10/N2 supermagnetron plasma chemical vapor deposition (CVD) method. Resistivity and hardness decreased with increase of upper electrode rf power (UPRF) under constant lower electrode rf power (LORF). Film thickness increased linearly to over 0.3 μm with deposition time via intermittent deposition. The film exhibited good adhesion to the substrate. Low-resistance thick films were deposited using alternating multilayer CVD at UPRF/LORFs of 1 kW/1 kW and 300 W/300 W. In the deposited alternating multiple layers, resistivity significantly decreased with the increase of H layer (1 kW/1 kW) thickness, and film thickness significantly increased with the increase of L layer (300 W/300 W) thickness. By the deposition of H/L multiple layers, a film of 2.1 μm thickness and 0.14 Ω cm resistivity was obtained.

A new supermagnetron plasma etcher remarkably suited for high performance etching

A new type of plasma etcher named a supermagnetron plasma etcher equipped with two parallel cathodes and an annular permanent magnet was developed. Using the supermagnetron plasma etcher, two kinds of experiments for the high rate etching of SiO2 and the highly uniform etching of photoresist and SiO2 under a stationary magnetic field were investigated. In the etchings of 6‐in.‐diam bare and patterned SiO2 wafers, high etch rates of 570 and 710 nm/min were obtained, respectively, using C2F6 gas of 7.5 mTorr. The etch selectivities of SiO2 to Si became as high as 6–15 using CHF3 gas at 3–6 mTorr. In a stationary magnetic field, the highly uniform etching of photoresist and SiO2 were also obtained using two types of supermagnetron plasma etchers. The etch uniformities depend on rf powers supplied to the upper and lower cathodes, gas pressure, and the position of a magnet, etc. High etch uniformities of ±5% were obtained without the rotation of a magnetic field in the etching of 3‐in.‐diam photoresist film an...

Physical properties of nitrogen-doped diamond-like amorphous carbon films deposited by supermagnetron plasma chemical vapor deposition

Diamond-like amorphous carbon films doped with nitrogen (DAC:N) were deposited on Si and glass wafers intermittently using i-C4H10/N2 repetitive supermagnetron plasma chemical vapor deposition. Deposition duration, which is equal to a plasma heating time of wafer, was selected to be 40 or 60 s, and several layers were deposited repetitively to form one thick film. DAC:N films were deposited at a lower-electrode temperature of 100 °C as a function of upper- and lower-electrode rf powers (200 W/200 W–1 kW/1 kW) and N2 concentration (0%–80%). With an increase in N2 concentration and rf power, the resistivity and the optical band gap decreased monotonously. With increase of the deposition duration from 40 to 60 s, resistivity decreased to 0.03Ω cm and optical band gap decreased to 0.02 eV (substantially equal to 0 eV within the range of experimental error), at an N2 concentration of 80% and rf power of 1 kW(/1 kW).

Probe diagnostics of supermagnetron plasma with applications of continuous and pulse-modulated rf electric fields

Parameters of supermagnetron plasma produced by rf (radio frequency) pulse, with 49.6 ms on and 0.4 ms off, were investigated by probe characteristics measured at 10–100 μs after the rf pulse in order to avoid disturbance in the measurement. The plasma parameters obtained by a continuous rf electric field and the phase differences of the rf electric field to both parallel electrodes were compared with those of rf pulse plasma. A double probe was mainly used in Ar as a standard gas, and a single probe was used in He gas for rf electric field free measurements using pulse-modulated rf plasma. He gas was used for extended time measurements because of a low probe contamination as a result of sputtering from two electrodes. A high electron density of an order of 1011 cm−3 was observed at low gas pressure (20 mTorr) for Ar plasma, and a low electron temperature of 1.1–1.2 eV was observed for He rf plasma. As for an rf phase difference dependence between two rf powers supplied to two parallel electrodes, maximum...

Diamond-Like Amorphous Carbon Films Deposited for Field-Emission Use by Upper-Electrode-RF-Power-Controlled Supermagnetron Plasma

Nitrogenated and hydrogenated diamond-like amorphous carbon (DAC:N and DAC:H) films were synthesized using i-C4H10/(N2 and H2) supermagnetron plasma, respectively. The upper- and lower-electrode rf powers (UPRF/LORF) were controlled to be 100–800/100 W, and N2 and the H2 concentrations were selected to be 25 and 20%, respectively. In the DAC:N layer deposited at 300/100 W, the nitrogen atom concentration was measured to be 1.7 mass %. In the case of DAC:N film, the lowest threshold electric field intensity (ETH) was observed to be 12 V/µm at the growth condition of 300/100 W. In the case of a DAC:H planar structure, the lowest ETH was 13 V/µm for 800/100 W deposition. In both types in the films with the lowest ETH, we observed the same optical band gap of approximately 1.2 eV. The optimum distribution and size of sp2 CC nanoclusters formed in both the DAC layers probably caused the ETH to decrease.

Luminescence Properties of Amorphous Carbon Films Formed Using Supermagnetron Plasma

Polymer-like amorphous carbon (a-COx:H and a-CNx:H) films were deposited using two types of supermagnetron plasma, i.e., Ar sputter and i-C4H10/N2 chemical vapor deposition (CVD), respectively. The sp2 clustering of these films was proved experimentally by Raman scattering and the estimation of optical band gap. The photoluminescence (PL) and electroluminescence (EL) properties of these films were measured and analyzed. As a result, a-COx:H films deposited by Ar sputtering showed similar peak energies for PL and EL (1.9–2.0 eV), while a-CNx:H films deposited by i-C4H10/N2 CVD showed large shifts between peak energies for PL (2.2 eV) and EL (1.7 eV). The differences in peak energies in the latter were ascribed to the luminescence characteristics caused by sp2 clusters embedded in the sp3 carbon matrix.

Electrical conductive hard-carbon (diamond-like carbon) films formed by i-C4H10/N2 supermagnetron plasma chemical vapor deposition method

Abstract Electrical conductive hard-carbon (diamond-like carbon, DLC) films were formed using a supermagnetron plasma chemical vapor deposition (CVD) method. Using a mixture of i -C 4 H 10 and N 2 gases, DLC films were deposited on thermally oxidized Si wafers, and the film deposition rate, hardness, and resistivity were measured. Two rf powers of the same frequency (13.56 MHz) with a rf phase difference of 180° were supplied to each electrode. The lowest resistivity of 1.7×10 3 Ωcm was observed at a N 2 concentration of 70%, at a gas pressure of 50 mtorr, an electrode temperature of 80°C, and at rf powers of 900 W/900 W. In this case, measured film deposition rate and hardness were 2300 A/min and 1700 kg/mm 2 , respectively.