Particle measurements on technical surfaces

Technical surfaces are found everywhere in the close environment of the critical product. These surfaces are e.g. the walls of a process chamber, the inner shield of a transportation box for silicon wafers or the surface of a cleanroom working table. The materials are plasstics, non-ferrous metals of metals. At the moment it is not possible to examine the cleanness level of such a surface in a large area and within a economical timre range. The way of examining technical surfaces under a Scanning Electron Microscope (SEM) requires a work-intensive sample taking. Also the size of a probe is limited. With a non destructive image processing system at an optical microscope such surfaces can be examined on their dgree of contamination within a very short time and in a large area. Particles down to 0,5 fm are detected depending on the roughness of the surface. Combined with a statistical computer evaluation and an x-y-stage the image processing system can record and evaluate the particle con taminsation of a technical surface within a very short time. The duration of the measurement also depends at the particle concentration on the surface. Using such an installation cleansing procedures and their effects on technical surfaces which are applied in "clean" manufacturing equipment can be compared.