Conformal deposition of a silicon-oxide and a fluorocarbon on a nano-shaped material in supercritical carbon dioxide
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0890-Y08-14.1
Conformal deposition of a silicon-oxide and a fluorocarbon on a nano-shaped material in supercritical carbon dioxide Takashi Shimizu, Kenichi Ishii, and Eiichi Suzuki Nanoelectronics Institute, National Institute of Advanced Industrial Science and Technology 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan ABSTRACT A novel surface engineering of nano-shaped materials, i.e., surface coating in supercritical fluid is proposed. Conformal deposition of a silicon-oxide thin film in supercritical carbon dioxide (scCO2) where O2 gas is miscible as an oxidizing agent is demonstrated. A uniform silicon-oxide film has been deposited even on backside of a nano-shaped SiO2, which is hard in the standard chemical vapor deposition. Filling of a Si-oxide into the horizontal gap has also been successfully achieved. Deposition of a fluorocarbon in scCO2 were tried to investigate surface modification using scCO2, and a hydrophilic SiO2 surface became water-repellent after the surface modification. These results indicate that the developed surface engineering in the supercritical fluid is promising technology in nanoscale device fabrication and micro (nano-) electromechanical systems. INTRODUCTION Recently, conformal deposition of a thin film is more and more important for a microelectronic device fabrication. Both complete conformal coverage of a narrow via and complete filling of the narrow via are one of the major topics for the ultra large semiconductor integrated circuit technology [1]. Complete conformal coverage of a complex 3-dimensional (3-D) micro (nano) structure is also promising for micro sensors and/or micro electromechanical devices (MEMS). It will supply several additional physical/chemical properties after construction of the final 3-D structure, which will be effective for controlling or adjusting device parameters. However, the complete conformal coverage of the 3-D structure requires conformal backside deposition with a film, which is difficult even for the chemical vapor deposition (CVD) method. Therefore a new technology for the conformal backside deposition of the film in which uniform nucleation can be achieved on the backside surface of the 3-D structure is required. In this paper, we propose a novel surface engineering of a nano-shaped material using supercritical fluid. We propose conformal backside deposition (CBD) of a film on a 3-dimensional micro (nano) shaped material under supersaturated supercritical solution induced by thermal heating under constant pressure (SSS-H or triSH). We show CBD of an oxide film on a nano-eave of SiO2, which was fabricated by dry etching process. An attempted to control hydrophilic/hydrophobic surface of the 3-dimensional nano-eave using the supercritical solution is also demonstrated. CONFORMAL BACKSIDE DEPOSITION USING SUPERCRITICAL SOLUTION Our strategy to obtain conformal backside coverage of the nano-shaped material with the deposited film is to enhance nucleation of the film on backside surface of the nano-shaped material. Figure 1 shows a schematic diagr
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