Abstract: A thin film semiconductor gas sensor including a metal oxide semiconductor sensor layer whose electrical resistance changes in dependence upon the nature and concentration of a gas being detected and having a heating element integrated therewith is improved by forming the sensor from a semiconductor body having a shell zone located relatively close to an outer surface of such body and being doped to the point of degeneration, with two spaced apart metal contact strips being positioned on such doped shell zone for connection with a current source to heat the sensor.

Abstract: The disclosure pertains to alignment procedure applicable in the case of x-ray lithography which is to be effected with the help of a mask which is arranged between the semiconductor body and the radiation source. The disclosure is characterized by a fixed association of the mask with respect to the semiconductor body during alignment and a relative displacement of the source location of the x-ray beam with respect to the mask and semiconductor body for example by bodily movement of the x-ray source components. With this system, by displacement of the radiation beam at its source end by the order of millimeters one can obtain an effective adjustment of the mask with respect to the substrate of the order of approximately 0.1 .mu.m.

Abstract: In the illustrative disclosure, alignment of x-ray masks, with elements in the submicron range for x-ray lithographic replication, is carried out with the use of through-bores in the set of masks and in the substrates. A single point x-ray source may be used to produce widely offset parallel beams defining the bore alignment axes, or the bores may be formed with oblique axes converging at a point, so as to be usable with diverging x-ray beams from a point x-ray source.