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Chemical Etch Rate of Plasma‐Enhanced Chemical Vapor Deposited SiO2 Films: Effect of Deposition Parameters

1997; Institute of Physics; Volume: 144; Issue: 8 Linguagem: Inglês

10.1149/1.1837908

1945-7111

R. S. Besser, P. J. Louris, R. G. Musket,

Copper Interconnects and Reliability

One of the most used diagnostics for characterizing silica thin films is the etch rate (ER) in acidic, fluoride‐based solutions The ER measurement is relatively easy, fast, and cheap, which makes it attractive as an in‐process monitor. For microelectronics, this monitor is extremely useful when it indicates the electrically insulating qualities of the film. In this paper we consider the chemical etching behavior of plasma‐enhanced chemical vapor deposited thin films prepared over wide ranges of deposition parameters. The ER, breakdown field strength, refractive index, density, oxygen to silicon ratio and residual stress of the resulting films showed wide variation. Correlations of these properties to the deposition parameters showed that the ER is an excellent monitor for breakdown strength and electrically insulating properties of these films. Slow etching rate was found to result from a higher substrate temperature, higher pressure, lower silane flow, and higher power. While many physical features of the film affect ER, we found that variations in the porosity of the film were dominating. Consistent with this picture, greater magnitudes of compressive stress resulted in slower ER, but only on relatively porous films deposited at low temperature. Composition did not have an appreciable effect.