Micropatterning of Chemical-Vapor-Deposited Diamond Films in Electron Beam Lithography

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Abstract
The micropatterning of chemical-vapor-deposited (CVD) diamond films using electron beam lithography technology has been investigated. The use of metal naphthenates as mask resist materials is proposed, because of their resistance to oxygen plasma in order to form an oxide film on the surface. The exposure characteristics of metal naphthenates, as well as the etching characteristics of CVD diamond and metal naphthenate films processed with electron cyclotron resonance (ECR) oxygen plasma were investigated. Furthermore, the crystal structure of CVD diamond micropatterns fabricated by this process was evaluated using Raman spectroscopy. We found that the metal naphthenates exhibited negative exposure characteristics upon electron beam irradiation. The sensitivity and the gamma value were 2.4×10-3 C/cm2 and 1.6, respectively. A maximum etching selectivity of 10 was obtained under etching conditions of a microwave power of 300 W and oxygen gas flow rate of 3 sccm. Line micropatterns 1 µm and 0.5 µm in width with a height of approximately 1 µm were fabricated with an etching time of 1 h. The crystal structure of the CVD diamond films after etching and the line micropatterns fabricated by this process remained constant; Raman spectra indicated only the presence of a diamond (sp3 bonding) peak at 1333 cm-1.