Quantitative analysis on the oxygen diffusion in pyramidal textured surfaces of silicon and copper via transmission electron microscopy

Abstract

In the process of microelectronic device fabrication, the oxygen atom plays a double role. It oxidizes Si producing the SiO2 layer. Moreover, it oxidizes the metal electrodes causing failures and enters the semiconductor acting as an impurity recombination center. This phenomenon is closely related to the oxygen diffusion in the material surface. Although a textured material surface is frequently used, the oxygen diffusion inside this surface is rarely studied. Studies are available only for planar material surfaces. In this work, monocrystalline Si slices with a pyramidal textured surface and a series of Cu films, which were deposited onto this substrate, were thermally oxidized. The oxygen diffusion in such textured surfaces was quantitatively analyzed via transmission electron microscopy. The oxygen distribution and the variation in the oxygen:cation atomic concentration ratio as a function of the oxide thickness were obtained. Thus, suboxide diffusion layers of SiOx and CuOx were found for the surfaces. In addition, the oxidation rate of the textured material surface was significantly reduced due to its lower oxygen partial pressure when compared to a planar surface. These results can be used to control the oxide thickness, to resist the electrode oxidation, and to reduce the concentration of oxygen recombination centers when using a textured material surface for optoelectronic devices.