Substrate processing apparatus

An apparatus for coating substrates by vapour deposition consists of a plurality of work stations in each of which is mounted an apertured mask which may be brought accurately into alignment with a substrate, a source of vaporizable material and a monitor slide which is coated at the same time as the substrate to determine the thickness of the deposit. The apparatus described (not shown) contains 24 such work stations, each of which contains a mask which may be moved from a position of rest in a horizontal plane upwards in contact with the substrate. The latter may also move from one work station to the next (with a differently apertured mask) thus providing multi-coats on the substrate. Alternatively 24 substrates can be coated in a single vacuum evaporation stage using the same or different masks in each station. The apparatus (not shown) consists of a bell jar 1, Fig. 1, mounted on a base plate 2 and divided by vertical sectors forming the work stations. In each station is mounted a source 54 of coating material, which may be varied from station to station. Substrates 77B, masks 80B, and monitor slides 72A, Fig. 2, are mounted on circumferential pairs of rails, e.g. 78, 79, which are moved as required by external cranks operating concentric central shafts having laterally extending arms supporting the rails. In operation, Figs. 4A, 4B, the substrate 77B mounted on carriers above the mask 80B is moved over the mask which then rises in is brought into accurate alignment by studs and spring members. The upper surface of the substrate is in contact with a copper cooling pad 66 above which liquid nitrogen circulates through tubes 67-71. Vaporized material passes upwards to the coating zone through a slot in a movable shutter 60, Fig. 2, and coats the substrate through the mask and also a limited area of a monitor slide 72A, which is connected to a resistance meter to record the thickness of the coating. The vaporizable material 54, Fig. 5, is mounted in a small diameter carbon channel mounted at each end in solid carbon plugs, connected to an electrical power source. Coatings described are (1) tin through a mask (2) insulating layer of silicon monoxide without a mask (3) lead through a mask.