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Investigating New Precursors for Silicon Dioxide

Raija Matero 1Suvi Haukka Marko Tuominen 

1. ASM Microchemistry, Väinö Auerin katu 12 A, Helsinki 00560, Finland

Abstract

Silicon dioxide is a widely used material in semiconductor industry. It is used for instance as a gate oxide and as a dielectric layer in dynamic random access memories (DRAM). Recently, other possible applications have evolved that would require good step coverage and good SiO2 filling capabilities, for example shallow trench isolation (STI). ALD has been proposed as a possible technique to meet these more stringent requirements. Unfortunately, the growth rate per cycle has traditionally been low for ALD SiO2 processes making the processing economically non-viable. New precursors with higher reactivity enabling higher growth rate are therefore needed.

In this study, two silicon precursors were tested: tris(dimethylamino)silane (trisDMAS) and SAM.24 from Air Liquide. Ozone was used as the oxygen source. The depositions were done in ASM Pulsar®2000 ALCVD™ reactor on 200 mm silicon wafers. The film thickness and uniformity were determined with a spectroscopic ellipsometer.

TrisDMAS was tested at 250 – 325 °C. Only very low growth rates were obtained when a 0.2-s trisDMAS pulse was used, the growth rate was increased from 0.07 to 0.09 Å/cycle with increasing deposition temperature. The film non-uniformity was also increased with increasing temperature from 5.4 to 10% (Uf 1σ). The highest growth rate was achieved with 0.5-s precursor pulses at 275 °C: 0.15 Å/cycle. The non-uniformity% was 4.8.

Depositions using SAM.24 were done at 250 and 300 °C. When 0.5-s precursor pulses were used, the growth rate and non-uniformity% were 0.15 Å/cycle and 4.8% at 250 °C, and 0.35 Å/cycle and 4.7% at 300 °C. A higher growth rate of 0.4 Å/cycle was achieved both at 250 and 300 °C using 1.0-s precursor pulses.

In this paper, the effect of deposition parameters on the growth of SiO2 will be presented.

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2007, Symposium C, by Raija Matero
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-14 15:25
Revised:   2009-06-07 00:44