Experimental study of nanoparticle generation during high-density plasma chemical vapor deposition of poly-Silicon films

High-density plasma processes with plasma densities exceeding 10(11) cm(-3) are being employed more in semiconductor fabrication processes because they provide higher deposition rates and highly anisotropic etching. However, relatively few studies on the formation of contaminant particles during these processes have been reported. In this work, particles generated during inductively-coupled plasma chemical vapor deposition (CVD) of poly-Si films are investigated using transmission electron microscopy (TEM). At 10 and 12 mTorr, TEM measurements were performed to obtain particle diameter and morphology information. The particle sizes were found to be highly uniform with relative standard deviations much less than 0.2. Furthermore, the surface morphologies of the particles changed from smooth to rough as the particles grew. These observations suggest that particle growth occurs by surface deposition of molecules (or ions). Initially, particle growth rates are constant regardless of particle diameter, which is consistent with transport or surface-reaction-limited growth in the free-molecule regime. As particles grow, particle growth rates gradually decrease until they vary in inverse proportion to the square of the particle diameter. We hypothesize that this decrease occurs when the particle's surface area is sufficient to cause depletion of depositing molecule (or ion) concentrations.