Low Temperature Deposition of SiO2 by Distributed Electron Cyclotron Resonance Plasma‐Enhanced Chemical Vapor Deposition

Abstract

Silicon dioxide thin films have been deposited at low substrate temperatures (Ts < 120~ using a microwave plasma. A new type of microwave excitation, the distributed electron cyclotron resonance (DECR), which provides high density plasma (~ 1011 cm -3) of low-energy ions, has been used. Pure N20 and Sill4 are mixed in the discharge. At constant pressure (0.1 pa), the ratio of N20 flow to Sill4 flow (Ro) was varied from 1-9. We have studied the effects of the gas phase composition at two different microwave powers (800 and 1200 W) on the refractive index, atomic composition, infrared absorption bands, etch rate, and electrical properties of the films. For ratio Ro larger than 4, near-stoichiometric films are obtained, with N and H atomic contaminations below 2 and 5 atomic percent (a/o), respectively, even at low temperature and without post deposition annealing. For Ro = 9, the films have physical and chemical properties similar to those obtained by RF plasma enhanced chemical vapor deposition at 350~ in terms of refractive index in the range of 1.47-1.48, etch rate in "P-etch" (6/~/s), and Si-O-Si stretching mode vibration (1058 cm-1). These films exhibit, at Ro = 9 and 1200 W, electrical resistivity of 10 ~ 1] cm and critical field larger than 3.5 MV cm -~, without post-deposition annealing.

Electrical properties of electron cyclotron resonance plasma-deposited silicon dioxide: effect of the oxygen to silane flow ratio

“…Critical fields, E c , were obtained from quasistatic currentvoltage measurements performed with a constant-voltage ramp with the device biased in accumulation. E c is defined as the field to pass 1 nA cm −2 through the Al gate [4]. In order to obtain more evidence on the nature of the defects present in the films, devices with two different contact areas were measured.…”

“…Plasma-enhanced chemical vapour deposition (PECVD) at very low temperatures has produced SiO 2 films of respectable electrical quality in comparison with thermally grown oxides. A large effort is currently being devoted to investigate the electrical properties of PECVD SiO 2 deposited at low temperatures [1][2][3][4][5]. We have recently reported low-temperature deposition by electron cyclotron resonance (ECR) plasmas of SiO 2 layers with optical, infrared and etching properties very close to those of thermal oxide [6].…”