EXPERIMENTAL STUDY ON SPUTTER ION PUMP FOR WIDE PRESSURE RANGE

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The experimental investigation of a sputter ion pump were performed for wide pressure range. The vacuum chamber has a diameter of 6 inches and an length of 200mm. The Lanthanum hexaboride (LaB6) disk of 50mm diameter are used for sputter cathode. The experimental device consists of discharge section and analysis one. The measurements involves ionization gauge, partial pressure gauge, electro static probe for plasma parameters and XPS measurement. The experiment was done by using a glow discharge plasma' and to create boron like thin films on the chamber wall surface. The preliminary experiment showed that the boron film formed on the vacuum wall can pump effectively water vapor. The experiment investigate the correlations between partial pressures of H2O,H2, O2 and plasma parameters of density, temperature and sputter film characteristics during a sputter discharge. The application of LaB6 cathode is a characteristic point of the experiment for developing a new type of sputter vacuum pump. The plasma parameters were measured by Langumuir probe and were estimated to be (2-30) x10^9 of density and 3-5 eV of temperature. The partial pressure was measured by QMS.The most typical result of the experiment is that the water vapor is pumped effectively for wide pressure range by using the LaB6 sputter cathode. The pumping speed is estimated to be about 4m^3/ (m^2s). XPS was performed on the sample tip inserted in the sputter discharge. The signals of B,La, O and C were detected. And the depth profiles of their signals were also measured. The experiment indicated that the sputter discharge with LaB6 cathode can be used for a new type of sputter vacuum pump.