Quadrupole mass spectrometers(QMS) are widely used instruments for partial pressure measurement and vacuum diagnostics. The calibration system for a partial pressure analyzer was designed and set up. Using this system, calibration and characterization for two commercial QMSes were performed. The thermal desorption spectroscopy systems(TDS) for metal, semiconductor and CRT were designed and constructed with the calibrated QMSes. Outgassing measurement of stainless steel, contamination analysis of Si wafers, diagnostic of CRT process were carried out with these systems.
The results are as follows :
1. The calibration system for a partial pressure analyzer was designed and set up. In this system, the main chamber is evacuated by a turbo pump through the orifice plate which is used to control effective pumping speed. Variations of pressure are measured by well characterized extractor gauges. The gas introduction system is consisted of leak valves, capacitance diaphragm gauges and independent pumping system.
2. Using this system, the linearity of two commercial quadrupole mass spectrometers and the influence of operating parameters(emission current, detection mode, SEM voltage) on the sensitivitiey have been investigated over the pressure ranges of 10-4 - 10-8 Torr for N₂, CO, Ar, O₂, H₂ gases. The sensitivities of quadrupole mass spectrometers were greatly influenced not only by gas species but also by operating parameters.
3. Sensitivities of QMS has been investigated over the pressure ranges of 10-2 - 10-6 Pa(10-4 - 10-8 Torr) for CO, H₂, Ar and mixed gases. The dependance of the signal developed from a constant partial pressure trace gas as a function of the pressure of matrix gas was studied. The results demonstrated that the sensitivities of CO and H₂ were greatly influenced by matrix gas species and pressures.
4. Thus, for all quantitative applications, it is necessary to carefully characterize quadrupole mass spectrometers.
5. The thermal desorption spectroscopy(TDS) system for metal was designed and constructed. The system is consisted of 3 parts, a measurement chamber with a QMS attached, a sample chamber with heating stage, a gas introducing chamber, with their independent pumping systems. The resistive heating stage could be controlled sample temperatures up to 1000℃ with required ramp rates. The outgassing rate and amount from the sample could be measured and calculated by the QMS and vacuum gauges.
6. The outgassing from stainless steel surfaces treated by several different methods have been studied by the TDS and compared each other. It was found that the electrochemical polishing and dissociated hydrogen gas treatment could reduce the desorption of water and CO/N₂. By AES experiment, the adsorption state of carbon on a H treated sample was different from that on an untreated sample.
The outgassing from some samples such as bare, TiN deposited and BN deposited on stainless steel substrates, were also measured by the TDS. The main outgassing species were water and hydrogen for all samples. The total outgassing is the largest for the bare stainles steel, and the least for the BN film. It was found that BN coating at 200 ℃ on stainless steel was more effective to reduce outgassing.
7. A heating stage and temperature control system for semiconductor was fabricated and characterized. With this system, the desorption of Si wafers, which were cleaned with various methods, were measured and compared. The RCA cleaning method was effective to reduce the outgassing..
8. The TDS system for diagnosis for CRT manufacturing process was designed and constructed. A variable conductance system was used in the system, where the effective pumping speed could be controlled from sub L/s to 100 L/s, and determined by the dynamic flow measurement principle. Using this system, outgassing and thermal desorption from part of materials of CRT could be measured and analyzed at various temperatures, these were useful to diagnose of manufacturing process.
9. TDS with QMS, is one of the most powerful quantitative analysis technique. It is a useful analysis tool in development of low outgasssing materials, in micro contamination control on semiconductor, and in diagnostics of vacuum manufacturing processes, such as CRT.