Abstract: By forming an intermediate etch stop material or by appropriately positioning an additional etch stop material in a spacer structure of a polysilicon line, the probability of exposing a shallow doped region of an active semiconductor region during a critical contact etch step for forming rectangular contacts may be significantly reduced. Thus, leakage current, which may conventionally be created by etching into shallow doped regions during the contact etch step, may be reduced.

Abstract: A monitoring device (18, 19 or 21) for optically monitoring residual contamination of oil particles is arranged downstream of filter zone for filtering water (9) in order to block off, if necessary, a discharge line (7). Circulatory operation in which the liquid is recycled through the filter zone (9) is preferably first switched in on exceeding a threshold value for the residual contamination, in order to overcome any eventually occurring "apparent contamination", for example small air bubbles, there is also provided mechanisms for distinguishing between residual and apparent contamination.