2006 Volume 90 Issue 5 Pages 288-296
Super-high-pressure mercury discharge lamps have been used as UV light sources in the photolithography exposure process. It is well known that these lamps applied internal pressure is more than 1MPa and the outer bulb temperatures reach over 500°C. Thus, the safety for rupture of the lamps has been a very important issues in their design. In this study, the effects of the following two factors on the rupture characteristics of the sealed parts were investigated experimentally, (1) joule heating in the current operation, (2) heat conduction from the discharge. In addition, the finite element calculation (FEM) was carried out to investigate the stress distribution in the sealed parts. The experimental results showed that the rupture occurred in the cooling process when the maximum temperature of the sealed parts was more than 1200°C. The numerical results showed that the maximum value of the maximum principal stress σ1 occurred near the point where a rupture initiated in the experiments. In addition, the experimental results were in fairly good agreements with the FEM results. The authors proposed that the maximum temperature of the sealed parts should be less than 1000°C during operation to prevent the lamp rupture.
