A bearing assembly for an electrical motor, including a shaft, a housing, and a main bearing between the shaft and the housing, the shaft being surrounded by a rigid sleeve for functioning as an auxiliary bearing in case of a breakdown of the main bearing and as a grease sealing under normal operation. One embodiment includes a method for manufacturing a semiconductor device in which at least an uppermost wiring layer is formed by a damascene method. Once screened, the individual materials may be ranked or otherwise compared relative to each other with respect to the material characteristic under investigation.