Last week I was in the beautiful city of Boston, among the red brick skyscrapers and the rarefied atmosphere of Harvard and MIT for Compound Semiconductor Week (CSW). CSW (actually 3 ½ days) is a combination of two conferences, the International Symposium on Compound Semiconductors and the Internal Conference on Indium Phosphide and Related Materials. It brings together academics, students and industrial scientists to present on topics ranging from antimonide based IR detectors, the use of graphene to make Field Effect Transistors (FETs) to the Metal-Organic Chemical Vapour Deposition (MOCVD) synthesis of GaN. As an applications engineer who spends a lot of time thinking about plasma and making holes in samples, it was interesting to discuss completed devices and the other process which go into forming them.

Oxford Instruments Plasma Technology was presenting a poster on the ICP etching InP with chlorine and argon. The mainstream process of etching InP with methane, chlorine and hydrogen has many advantages including a wide process window and low substrate temperature. However, hydrogen can alter the electrical properties of semiconductors and the process produces carbon-based polymers which coat the sample and chamber increasing process steps and cleaning times. The chlorine-argon process is polymer and hydrogen free and provides an alternative process for certain types of InP etching. The process can be tracked using optical emission spectroscopy (OES) which looks at the spectrum of light from the plasma to determine which layers are being etching.

There was a keynote session on gallium oxide. β-Ga₂O₃ is a transparent conducting oxide with an exceptionally high band gap (≥4.8 eV) and a very high breakdown electrical field (E_br = 8 × 10⁶ V cm⁻¹). This makes it an ideal material for the next generation of high-frequency communication systems and energy-efficient power electronics. Current devices are scaled close to the limits of their operating voltages. New materials will have to be found if the energy efficiency of devices is going to continue to increase. Papers were discussed on diverse topics from the synthesis of Ga₂O₃ via melt growth and vapour phase epitaxy, the difficult of doping β-Ga₂O₃ and the formation of solid solutions with Al₂O₃ to the production of complete test devices such as FETs.

The conference provided an excellent overview of the current research in the semiconductor community. Now to get back to work so I have data to present at CSW2019 in Japan!

For any questions about Oxford Instruments Plasma Technology processes or products send an email to: plasma-experts@oxinst.com

Author: Dr Katie Hore