A compact electron cyclotron resonance(ECR) plasma system composed of a microwave generator and a magnet coil was fabricated. A Langmuir single probe was used to investigate the plasma characteristics of the system through I-V measurements. The performance of the compact ECR plasma system was tested for the case of silicon etching reaction with $CF_{4}/O_{2}$(30%) mixed gas. Electron density and etch rate increased to maximum values and then decreased with increasing argon gas pressure, but electron temperature changed in the opposite way. The electron density and the electron temperature of argon gas plasma were 0.85${ imes}~5.5{ imes}10^{10}cm^{-3}$ and 4.5~6.0 eV, respectively, in the pressure range from $3{ imes}10^{4}$ to 0.05Torr. The etch rate reached a maximum value at the position of 2.5cm from the bottom of plasma cavity. Etch rate uniformity was $pm$6% across 6cm wafer. Anisotropic index was 0.75 at 1.5${ imes}10^{-4}$Torr.