Monitoring of surface roughness of plasma-deposited films using optical microscopy-measured dark particle...

We present a dark field microscopy for the measurement of film surface roughness. The underlying principle is that a darker region in a film surface represents a deeper place from the top surface. The performance of the imaging system was demonstrated for silicon nitride films deposited in a SiH4-NH3 plasma. The system provided distributions of particles and the tendency of particle counts was compared with that of AFM-measured surface roughness. A strong correlation identified between them represents that the system is a viable alternative to AFM. The system is expected to find applications to roughness measurement during a real-time plasma processes.