Ultrahigh-resolution leak-testing method using liquid-nitrogen chilled vacuum integration chamber

摘要

An ultrahigh-resolution leak-testing method has been developed for microelectromechanicalsystem (MEMS) sensors such as a vibrating angular-rate sensor housed in a vacuum package. In this method, a package filled with helium gas was kept in a small integration chamber to accumulate helium gas leaking from the package. After the accumulation, the chamber was chilled with liquid-nitrogen, and background gases except helium gas were adsorbed on the wall of the chamber because the boiling point of nitrogen is much lower than those of the background gases. The leak-rate resolution of the method reached 1×10{sup}(-17) (Pa·m{sup}3/s) under the conditions of a baking time of 120 minutes at 150°C, an evacuation time of 60 minutes, and an integration time of 6-13 days. This resolution is 10{sup}5 times superior to that of the conventional vacuum integration method. The accuracy of the leak rate measured was verified using a standard helium gas leak source.