Electron cyclotron resonance plasma source for metalorganic chemical vapor deposition of silicon oxide films

Abstract

An electron cyclotron resonance (ECR) plasma source was employed for low-temperature (50–300 °C) metalorganic plasma-enhanced chemical vapor deposition of silicon oxide films. The plasma was excited in mixtures of oxygen and tetraethylorthosilicate vapor, and oxygen and tris(trimethylsiloxy)boron (TTMSB) vapor. The operation pressure range was 1–50 mTorr; oxygen and metalorganic vapor flow rates varied from 10 to 100 sccm. Microwave power (f=2.45 GHz, P=100–1500 W) was introduced into a 15-cm-diam ECR chamber via a microwave quartz introduction window. A static magnetic field in the plasma chamber was generated by two Helmholtz coils. It had intensity near the microwave window, Bvw=875–935 G in a narrow plasma mode, and Bvw=1000–1100 G in a uniform plasma mode. Silicon dioxide films were deposited onto a 10-cm-diam silicon wafer located at 16 cm from the source output. A line-averaged plasma density N̄e was measured with a microwave interferometer (35 MHz) at 11 cm from the source output. In the mixture of TTMSB vapor and oxygen (20 mTorr), N̄e was 1.5–1.7×1011 cm−3 and then decreased as pressure grew. The film deposition rate increased with TTMSB flow rate; it had a maximum value of 1200 Å/min at total pressure of 15–20 mTorr.