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In this work, the thermal reactive ion etching (TRIE) technique for etching hard-to-etch materials is presented. The TRIE technique employs a self-heated cathode and a thermally insulated aluminum plate is placed on the cathode of a regular reactive ion etching (RIE) system. By optimizing the beam size to support the sample stage, the temperature of the stage can be increased to a desired temperature without a cathode heater. The technique was used to etch a bulk titanium plate. An etch rate of 0.6 μm/min and an etch selectivity to nickel of 100 were achieved with SF6 plasma. The proposed technique makes a regular RIE system a more powerful etcher without the use of chlorine gas, a cathode heater, and an inductively coupled plasma source.

Strain and stress at the Si surface have been studied by photoreflectance (PR) spectroscopy. A Si diaphragm structure has been fabricated in order to produce the surface strain caused by N2 gas pressure which changes the PR spectra of the Si diaphragm. The transition energy obtained from the PR peak energy of approximately 3.4 eV is proportional to the surface stress, which is calculated by elastic analysis. Additionally, PR spectroscopy was applied to measure stress at the interface between the Si and thermal oxide. As the SiO2 growth temperature increases, the interface stress decreases. From our experimental results, it is considered that PR spectroscopy is effective as a contactless and nondestructive monitoring technique for Si surface stress.

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