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Aluminum oxide films were etched using low energy argon ions generated by a microwave electron cyclotron resonance (ECR) source argon plasma. The argon ion energies were controlled by biasing substrates placed on a 13.56 MHz capacitively coupled electrode. Reactively sputtered aluminum oxide films were used to study the relationship between the dc bias applied to these substrates and the etch rate of their films. In situ x-ray photoemission spectra of the Al 2p and O 1s transitions showed that the ECR plasma was effective in completely removing native aluminum oxide and adventitious hydrocarbon in 1 min at ion energies as low as 100 eV. This preclean technology did not change the dielectric breakdown distribution of antenna structures with 12-nm-thick gate oxide capacitors.

The hydrogenating effect of a low-temperature, electron cyclotron resonance excited H2 plasma on the surface chemistry of thermal SiO2 films is analyzed in situ by x-ray photoemission spectroscopy and static secondary ion mass spectrometry. Hydrogenation with this nominal 10 eV proton flux results in Si-(O4), H-Si-(O3), (H2)-Si-(O2), (H2)-Si-O, and H-Si-(Si3) bonding states to the complete exclusion of Si—OH bond formation. A simple thermodynamic argument accounts for the exclusivity of Si—H bonds terminating the outermost (O3)-Si-O-Si-(O3) network of a thick SiOx<2 film, thereby transforming what is normally a hydrophilic surface into one that is hydrophobic.

Through‐the‐wafer via connections can provide low impedance contacts for normalGaAs FET's which significantly improve device characteristics. In this paper, we describe the use of a simple, thick, positive resist mask together with reactive ion etching in low pressure SiCl4/Cl2 mixtures. This process provides controlled via profiles suitable for connections through 100 μm thick substrates. The use of this process in the fabrication of a monolithic distributed amplifier resulted in a significant improvement in gain.

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