X-Ray Reflectometry Study of the State of the Surface Layer of Polished Silicon Substrates Depending on the Methods of Their Cleaning

The state of the surface layer of polished silicon substrates and the effect of surface-cleaning procedures, such as washing in an ultrasonic bath, etching, and vacuum annealing, is studied. The X-ray reflectivity technique is used to determine the root-mean-square (rms) roughness, thickness, and density of the damaged surface layer. It is shown that the substrates have a damaged surface layer 1.5 nm thick, which is most pronounced after annealing at 350°С. Based on the etching procedures and subsequent vacuum annealing, an approach is proposed for cleaning the surface from contaminants, the damaged layer, and obtaining substrates with a root-mean-square roughness of σ z = 0.42 nm. This approach can be used, in particular, for the deposition of thin organic films.