Catalyst-referred etching

K. Yagi, J. Murata, A. Kubota, Y. Sano, H. Hara, T. Okamoto, et al.. Catalyst-referred etching of 4H SiC substrate utilizing hydroxyl radicals generated from hydrogen peroxide molecules. Surf. Interface Anal. 40 (2008) 998—1001. 

Plasma chemical vaporization machining (PCVM) and elastic emission machining (EEM) are ultraprecision machining methods based on chemical reactions that were developed in our laboratory. Their concepts and the results of basic research were described in a previous edition of Crystal Growth Technology [1, 2]. In this chapter, the results on both PCVM and EEM achieved since the first pubH-cation are described. In addition, a new abrasive-free planarization method called catalyst-referred etching (CARE) is introduced in the last part of this chapter. 

Fig. 14.5 XPS spectra of Pt 4f5/2 and 4f7/2 over the Pt(3 wt%)-Ti02 catalysts used in several solutions, (a) Before etching, (b) after etching by argon ion for 10 min, (c) reference samples.

The selectivity of both PdsGa samples (as milled and etched) were much higher than for the reference catalyst Pd/Al203. However, the etched sample did not reach a steady-state in selectivity. During 20 hours of experiment, its selectivity continuously increased - a process that apparently is closely related with the deactivation of the catalyst. 

Before electroless plating plastic parts, the surfaces have to be treated to ensure good adhesion. The etching process usually involves the use of a chromic acid solution to provide a microscopically roughened surface to the plastic part. The catalytic process is sometimes referred to as seeding. Here very small particles of an inactive noble metal catalyst, normally palladium, are deposited into the micro-cracks created during the etching process. The palladium will act as active catalyst sites for chemical reduction of the electroless... 

Catalyst Metal ion M HFM Temp °C/ etching time Metal deposit Si morphology References... 

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