Muneo Furuse

Effect of baking temperature and air exposure on the outgassing rate of type 316L stainless steel

The outgassing rates of a vacuum remelted type 316L stainless steel were measured as a function of baking temperatures, baking durations, and air exposure/baking cycles. Long‐time baking, as was expected, reduced the outgassing rate of the stainless steel. A subsequent air exposure and short‐time baking in vacuum was found to reduce the outgassing rate much more than the preceding long‐time baking. The outgassing rate after baking qAB was reduced with the repeated air exposure/baking cycles at a constant baking temperature. After a few air exposure/baking cycles, qAB was not reduced and remained constant with a further air exposure/baking cycle. This indicates that the surface of the stainless steel reached the steady state with respect to the outgassing as a result of the repeated air exposure/baking cycles. For this thoroughly degassed state, the effect of baking temperature was evaluated in the range of 150 to 450 °C. Six‐hour baking at 150 °C was sufficient to attain the outgassing rate of 1.3×10−10 P...

Spatial Distribution and Transport of an Electron Cyclotron Resonance Plasma Generated Using Dominant-Mode Microwave

The relationship between the plasma uniformity and the microwave electric field was investigated for various levels of microwave power by introducing only the dominant-mode microwave: either the circular TE11 mode or the rectangular TE10 mode. The plasma uniformity was found to change in three stages according to the electron density depending on the microwave transmission characteristics in the plasma. The fluctuations of the plasma emission were also investigated in several types of discharges. A fixed spatial distribution of the microwave electric field was found to be effective for stabilizing the plasma. The high-density plasma above 1×1011 cm-3 was found to be more stable.

The origins and elimination of oval defects in GaAs layers grown by molecular beam epitaxy

Oval defects in GaAs layers are serious impediments to GaAs device fabrication. Of particular importance is the relationship between the droplets deposited on the crucible walls and the number of oval defects. These droplets previously believed to be gallium oxides are shown to consist of GaAs shells covering the Ga particles. By increasing the wall temperature of the crucible orifice, and reducing the arsenic beam intensity, the density of droplets is reduced, thus decreasing oval defects. Using a uniform‐heated Ga effusion cell and adjusting the cell configuration, the droplets can be reduced substantially and the defect density can be reduced from >104 cm−2 to less than 200 cm−2.

Spatial Distribution Measurement of Microwave Electric Field Using Thermal Sensitive Paper in a Microwave Etching System

A method for 2-D measurement of microwave electric field distribution using thermal sensitive paper has been developed. This measurement method has little influence on the microwave propagation and the plasma generation. In a cavity-resonator microwave plasma generation system, the relationship between the plasma uniformity and the microwave electric field distribution was investigated using this method. The cavity-resonator microwave plasma source was found to generate high-density plasma stably and uniformly over a large area through the excitation of a ring-shaped microwave electric field in the cavity resonator.

Production of highly uniform electron cyclotron resonance plasmas by distribution control of the microwave electric field

We have developed the apparatus that can measure the three-dimensional distribution of microwave electric field intensity in electron cyclotron resonance (ECR) plasmas to investigate production and control of ECR plasmas. The relationship between the plasma properties of ECR plasmas and the microwave electric field intensity in plasmas is studied. We have confirmed that the pattern of the radial distribution of the ion saturation current at the electrode is the same as that of the microwave electric field intensity at the ECR zone. If the distribution of microwave electric field intensity at the ECR zone is uniform, the distribution of plasma density on the electrode becomes uniform, even if the distribution of microwave electric field intensity of the other zone is not uniform. Therefore, in order to obtain the optimum distribution of plasma density on the electrode, the distribution of microwave electric field intensity at the ECR zone must be controlled.

Slant Slot Antenna-Type Electron Cyclotron Resonance Plasma Source

A new compact electron cyclotron resonance (ECR) plasma source, which is termed slant-slot antenna-type ECR plasma source, is presented. Using this plasma source an ion saturation current density Iis of 6.2 mA/cm2±5.2% was obtained over a diameter of 300 mm under ambient conditions of Cl2 gas at 0.7 Pa. The features of the plasma source are an independent circular TM011 mode cavity resonator and slot antennas mounted in the shape of a ring at a constant slant angle to the surface current flowing at the bottom of the cavity resonator. As the result, microwaves of TE01 mode and others having a ring-shaped the electric field distribution can be introduced into the reaction chamber with high stability. This plasma source can generate a plasma with a ring-shaped Iis distribution stably, and it can control the Iis distribution by means of both the configuration of the magnetic field and the pattern of slot antennas. Therefore, the plasma source can generate a uniform plasma under a wide range of discharge conditions.