5 - CVD Processes and Equipment

Abstract

This chapter discusses the chemical vapor deposition (CVD) processes. The factors controlling a CVD process are the thermodynamic, mass transport, and kinetic considerations, and also the chemistry of the reaction, the processing parameters of temperature, pressure, and chemical activity. The various CVD processes comprise the thermal CVD, laser and photo CVD, and plasma CVD. The difference between these processes is the method of applying the energy required for the CVD reaction to take place. The heating methods used in thermal CVD include various types of reactors such as the hot-wall reactors, cold-wall reactors, atmospheric and low-pressure reactors, and ultra-high vacuum reactors. The chapter discusses two methods based on photon activation, which are the laser and photo CVD. Laser CVD occurs as a result of the thermal energy from the laser coming in contact with and heating an absorbing substrate. The wavelength of the laser is such that little or no energy is absorbed by the gas molecules, while in photo CVD the chemical reaction is activated by the action of photons of the ultraviolet (UV) radiation, which have sufficient energy to break the chemical bonds in the reactant molecules.