1. Field of the Invention
The invention relates to a particle detector measuring instrument with a feed connection for a gaseous or liquid medium, and a measuring instrument for measuring the concentration of particles in the medium. The invention additionally relates to a device for processing semiconductor wafers which comprises such a particle measuring configuration, in order to control the processing on the basis of a signal generated by the measuring configuration.
During the production of particle-sensitive products, the contamination monitoring of the gas or liquid media processed assumes great importance. In particular during the production of electronic components on semiconductor wafers, because of the progressive automation and the structure widths becoming smaller and smaller, there is an increasing need for the most comprehensive contamination monitoring possible.
Particle measuring instruments are known which measure the concentration of particles within the gas or liquid medium. It is possible for solid-body particles or liquid particles in gases or solid-body particles in liquids to be detected. If, within a processing device for semiconductor production, the particle concentration has to be determined during operation (in situ), the measuring instrument is incorporated into a circulating or disposing medium flow. The particle measuring instrument is controlled via communication lines, and measured data values that are determined are interrogated. The instruments are constructed for use only within a specified range of fluctuation of operating conditions. If these operating conditions are exceeded, then there is a risk that erroneous measurements will be output, imparting a false image of the real relationships; in the limiting case, the particle measuring instrument can even be destroyed.
For example, in the area of deposition ovens for the thermal growth of layers, when the oven is being unloaded hot air can reach a particle sensor monitoring the mini environment, in such a way that the sensor is destroyed. In the area of wet-chemical processing with acids and alkalis, a pH of the liquid medium can rise in aggressive areas to such an extent that a sensor is likewise destroyed. In addition, the operating parameters of the medium can reach peak values within which the measuring sensor no longer operates reliably. In order to achieve permanent and automatic process monitoring, such conventional particle sensors are not reliable enough and are therefore unsuitable.