In-Situ Optical Pyrometry in the CVD of Metallic Thin Films for Real Time Contro of the Growth

In-situ temperature measurement is essential in CVD in order to control the temperature of the growing films. This is frequently achieved by optical pyrometry because it is a sensitive, convenient, and inexpensive tecnique that can be used in corrosive atmospheres. In this work, in-situ IR pyrometry has been used, not for direct measurement of the temperature, but for real time monitoring of the early stages of the growth of metallic-type thin films, selected as a model system. Significant variations in the pyrometric signal where observed during the metal-organic (MO) CVD of CrCXxNy thin films due to changes of emissivity of the film/substrate system. The pyrometric signal (or emissivity)depends predominantly on the nature, thickness, and surface roughness of the growing film. As a result, fruitful information as to the formation of an interphase, or the existence of an induction period, can be obtained in real time by this detection tecnique. Radiation pyrometry can be used as a surface diagnostic tool for the growth of a large variety of thin film materials that exhibit an emissivity sufficiently different from that of the substrate.