Oxygen diffusion process on the copper surface by contact resistance

It is known that very thin oxide film on the metal surface makes tunneling effect of electron. In the case of copper surface, there is a very thin insulation film on the top and fairly thick semiconductor layer is made the inner side if copper is left in the air so long time. Our purpose is to clarify the oxygen diffusion speed by measuring contact resistance between Au-Cu on the hot plate. Contact resistance is rapidly reducing to a low value, while the oxidation temperature is kept at 220 deg C. The thickness of oxide layer was measured by AES after the measurement to clarify the relationship between oxidation time versus film thickness. It is understood that film structure is changed from the thin insulator type to a semiconductor one within a few minutes. The diffusion speed is estimated about 10nm per minute at 220 deg C for single crystal oriented for (100). It is concluded that the diffusion speed of oxygen of crystal copper is 1.7 times higher than the one of poly crystal type.