Data is presented from two experiments with oxygen radicals. Both experiments use a quartz crystal microbalance (QCM). In the first, a silver-coated QCM is placed in the vacuum chamber and subjected to the plasma cleaning process. Oxygen radicals will incorporate themselves into the QCM and increase its mass. The flux of oxygen radicals impinging on the QCM surface can be calculated using the Deal-Grove model of surface oxidation. By locating the silver-coated QCM in different locations of a vacuum chamber, a map of oxygen radical concentrations as a function of distance from the plasma can be made. In the second, a gold-coated QCM is contaminated with hydrocarbons. Test contamination is achieved by heating a small amount of hydrocarbon in a vacuum chamber and allowing the evaporation to recondense on the gold-coated QCM. The cleaning process is then initiated and an experimental trace showing mass loss from the gold-coated QCM as a function of cleaning time is obtained.

A chemical box model which assumes that once the plasma is lit there is a steady-state oxygen radical concentration within each box can be compared to the data from the silver-coated QCM experiments. The chemistry within each box is obtained by using a standard database of gas phase reaction rates. The second model focuses on the gas surface chemistry of decontamination. The results of the second model are compared with the data from the mass loss traces of the gold-coated QCMs. The combination of both models will provide a means to estimate rates of downstream plasma cleaning for any contaminated vacuum system.

Cryogenic high vacuum pumps are used on a wide variety of vacuum substrate processing equipment, space simulation systems, and analytical instruments. They produce high pumping speeds for all gases and work over a wide range of pressures. Pumping residual gases occurs by cooling them to the point that they condense on the appropriate cryogenic surface. Thus, the pumping speed of the cryopump can be converted into deposition rate of the pumped gases onto cold surfaces inside the pump. The thickness of the deposited layer is uneven due to geometry of the cryopanels inside the pump. The majority of the trapped gas forms thick and comparable stable amorphous structures, while a significantly smaller amount of the pumped gas is participating in low rate deposition on those zones inside the pump that are less exposed to the gas flow. This low rate deposition leads to formation of polycrystalline films with complicated crystallographic structure even for the simple binary gas mixture widely used in the most applications in semiconductor industry. As with any thin film, this type of polycrystalline frost can be subject to appreciable residual stress due to structural defects. The concentration of such defects depend on operating conditions such as pumped gas composition, pressure, rate of deposition, and condensation temperature. For the stressed film there is always a certain film thickness (critical thickness, [1]) after which the film can exhibit one of the possible cracking pattern – surface crack, channeling, or debond. Defects in the condensed solid gas films grown inside the cryopump can lead to spontaneous delamination resulting in frost flakes being ejected from the array surface with subsequent sublimation on the warmer surfaces of the pump. Sporadic sublimation of delaminated flakes lead to unwanted pressure variations, or bursts, inside the vacuum system. This report discusses the types of film formations found in a typical cryopumping array structure and summarizes the development of a new cryopump with increased capacity and elimination of sporadic pressure bursts occurring during the cryopumping of type II gases. The pump employs the GM refrigeration cycle and is a further modification of the Brooks Automation On-Board IS 8F cryopump [2]. The test results showing pressure bursts free operation and 50% higher capacity for type II gas achieved with no changes to cryopump external geometry are presented and discussed.

Achieving a better base pressure and reducing bake-out time are the two important practices for an UHV system. Use of a sputter ion pump (SIP) in combination with non-evaporable getter (NEG) is one of the good solutions for this. Although many efforts have been made showing results of the pumping performances of NEG-SIP combination, the SIPs used were relatively large. Furthermore there is a demand for high performance, compact combination pumps that can be installed in a tight space in a storage ring of the proposed PLS-II project. Thus we tested the characteristics of a compact NEG-SIP combination pump (CNP) to see if the CNP can meet the above mentioned desires.

A compact getter cartridge mounted on CF40 flange (Capacitorr D 400-2) was used in combination with small SIPs, having speeds ranging from 10 to 60 l/s. The CNP was attached to a stainless steel chamber that has five CF40 flanges with a total inner surface area of 3,000 cm².

Base pressures (BPs) of the CNP-UHV system, in a wide range of situations, with/without NEG and with/without baking were measured. Significantly lower pressures and faster pumping could be achieved using the CNP. Base pressures of low 10^-11 mbar could be obtained with a compact NEG for 10 l/s and 60 l/s SIPs after a 48-h bakeout.

The results also show that the compact CNP can provide high pumping speed and reach 10^-11 mbar after a very short (few hours) bakeout. The BP was 1x10^-10 mbar with 60-l/s SIP alone after a 48-h bakeout, whereas it was 7.9x10^-11 mbar with the CNP; a better result after only 2-h bakeout. This is quite a remarkable decrease in the bakeout time of a UHV system.

It is worthwhile to note that UHV could also be achieved with the CNP even in a fully unbaked system: A pressure of 3.9x10^-10 mbar with the CNP was reached, while it was 8x10^-9 mbar with the SIP alone. The other interesting result of the CNP-UHV system is that the pressure increase is much less and slower when the SIP is switched off. This is also a good characteristic, required for portable vacuum devices.

All these characteristics are particularly useful for the design and operation of the vacuum system of a storage ring. It may also be beneficial for the miniaturization of vacuum equipments and mobile applications which require smaller pumping systems.

On the 90^th anniversary of the foundation of Edwards by FD Edwards, the origins of industrial vacuum processing are examined. They are then compared with progress at the time of FD Edwards’ death in 1966 and finally, possible developments are examined in the light of vacuum processing technology in 2009.

Proliferation of vacuum processes are shown to drive the evolution from mercury based vacuum technology through oil sealed pumping to dry pumping in the primary and secondary pumping pressure region resulting in a significant market for vacuum processing equipment.

Looking ahead, likely commercial influences are identified, such as electronic, environmental, and safety applications.

To meet that demand, trends and limitations in vacuum engineering are highlighted, particularly capacity, power and rotational speed. The benefits of applying electronics to vacuum processing become apparent - the very products vacuum processing equipment has helped to manufacture so successfully.