Use of nanoparticle-based solution processed technologies such as inkjet printing of inorganic material offers a potential strong reduction of silicon thin films production cost for large area electronic devices such as thin film transistors, solar cells or thermoelectric devices. After deposition a thermal step is required to restore the material functional properties. Classical thermal heating does not allow sufficient reduction of both process temperature and time. In contrast microwave sintering offers the key advantage of energy and processing time saving. Previous studies on heating of silicon particles have shown strong dependence on the surface chemistry of the particles: the presence of an oxide inhibits sintering below temperatures around 1100 °C. It is shown here by Raman spectroscopy on thin-films that onset of microwave sintering occurs at much lower temperature (~800 °C). Shrinkage of compacts is monitored for both types of sintering using classical thermal dilatometry and custom in situ real time temperature and shrinkage monitoring system. Two shrinkage stages are identified. Principal shrinkage stage during microwave heating takes place at lower temperature than for thermal sintering. Nevertheless densities obtained by microwave annealing are smaller. Major role of cavity atmosphere is put in evidence.