No abstract

Very smooth and vertical etching of InP by Cl2 reactive ion beam etching has been achieved under high temperature (≈200°C), high ion energy (≈1 keV) and low Cl2 pressure (∼10-5 Torr). The roughness is estimated to be a few nm by scanning tunneling microscopy and no contamination except for Cl was observed by in situ Auger electron spectroscopy. Under these etching conditions, the etched depth is precisely controlled (σ=22 nm) by simply monitoring the electrode curtent of the ion accelerating grid. Other III-V compound semiconductors, such as GaAs, InGaAs, AlGaInP and InAlAs have also been etched smoothly and vertically. Multilayers of these materials, such as InP/InGaAsP, AlGaInP/GaInP, and InAlAs/InGaAs/InP have been etched without steps between the layers on the sidewalls.

A photoeletronic bistable device with selectable light output channels has been fabricated for implementation in photonic switching and processing systems. The device is a variation of the vertical to surface transmission electrophotonic device. Output in the stimulated light emission mode was successfully obtained from different waveguide channels by external electronic switching. Output channels could be switched at a rate of 400 Mb/s. The potential versatility of this device has been experimentally confirmed in programmable or switchable optical interconnections.

It has been found that a reactive ion beam etching (RIBE) using Cl2 gas is useful for microfabrication of Y-Ba-Cu-O superconductors. The etching yield enhancement of Y-Ba-Cu-O is observed for Cl2 RIBE. The etching yield of Y-Ba-Cu-O at 400 V accelerating voltage, 2×10−3 Torr Cl2 pressure for Cl2 RIBE is 2, which is twice that for Ar ion beam etching. Y-Ba-Cu-O submicron patterns have been fabricated by focused ion beam lithography and Cl2 RIBE. Moreover, a Y-Ba-Cu-O superconducting line with a 4-μm linewidth has been fabricated by annealing an as-sputtered Y-Ba-Cu-O line pattern.

A new in situ fabrication process for GaAs is developed. In this process, electron- cyclotron-resonance oxygen plasma is used for the first time to form an oxide mask for Cl2 gas etching. Using this technique, the time and oxygen gas pressure required for the oxidation are drastically reduced, compared to other oxidation methods. Line patterns with submicron width are successfully fabricated by partial modification of the oxide mask by electron beam irradiation and subsequent Cl2 gas etching.