A planar one-dimensional particle-in-cell simulation with Monte Carlo Collisions (PIC/MCC) package has been used to study 13.56 MHz argon discharge including metastables species. Reactions such as metastable creation, ionization from the metastable state, metastable quenching to resonant level and collisions between two metastables were taken into account. The effect of pressure and applied voltage on the metastable density was examined. At high pressure and high voltage the metastable profile is slightly peaked at the sheath edges. At low pressure and low voltage the metastable profile are rather flat and the plasma density profile has a peak in the center of the discharge. The shape of the profile is determined by mean free path for electrons and metastables in the discharge. For high voltage and high-pressure cases an essential part of the ionization comes from multiple step ionization and metastable-metastable collisions.
