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Film Deposition: Dielectric, Polysilicon and Metallization
Published in Kumar Shubham, Ankaj Gupta, Integrated Circuit Fabrication, 2021
The metallization is usually done in vacuum chambers. A mechanical pump can reduce the pressure to about 10 to 0.1 Pa. Such pressure may be sufficient for LPCVD. An oil-diffusion pump can bring the pressure down to 10−5 Pa and with the help of a liquid nitrogen trap as low as10−7 Pa. A turbo molecular pump can bring the pressure down to 10−8–10−9 Pa. Such pumps are oil-free and are useful in molecular-beam epitaxy where oil contamination must be avoided. Besides the pumping system, pressure gauges and controls, residual gas analyzers, temperature sensors, ability to clean the surface of the wafers by back sputtering, contamination control, and gas manifolds, and the use of automation should be evaluated.
Mass Spectrometry
Published in Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus, Environmental Chemical Analysis, 2018
Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus
The turbomolecular pump contains a bladed turbine which rotates at high speed and sweeps molecules down into the throat of the pump from where the backing pump removes them. These pumps, because of their very high speeds, can be readily damaged if they are activated when the system is at a pressure of more than a few millimeters or if the system pressure rises suddenly. Because it takes a minute or two for the turbine to slow down, a sudden venting may do damage, even if a safety circuit cuts off the power when a pressure rise is detected. The turbomolecular pump is shown in Figure 5.4. At set intervals, the pump bearings must be lubricated or replaced. A record of hours of operation must be kept and servicing done at the specified times.
Ultrahigh Vacuum
Published in Marsbed H. Hablanian, High-Vacuum Technology, 2017
In regard to turbomolecular pumps, the achievement of ultrahigh-vacuum is, at least in the conceptual sense, very simple. It is only necessary to obtain a sufficiently high compression ratio and reduce outgassing at the inlet sections of the pump. In principle, regarding the basic pumping mechanism, turbomolecular pumps can function at any pressure encountered in high-vacuum technology (including atmospheric) (see the recently published general articles by J. Henning). There are some obvious limitations in commercially available pumps. They cannot be baked at the usual temperatures employed in ultrahigh systems and they require some bearing lubrication, which makes them not entirely free of the possibility of hydrocarbon contamination. Even magnetic levitation bearings do not eliminate the baking limit. Thus, the quoted turbomolecular pump ultimate pressure is near 1 × 10−10 torr. No doubt, with extensive baking and with the assistance of liquid-nitrogen traps or gettering pumps, the final pressure can be lowered to 1 × 10−11 torr or lower. The same result can be achieved using two turbopumps in series.
State of the Art in Cyclotrons for Radionuclide Production in Biomedicine
Published in Nuclear Science and Engineering, 2023
Mario Marengo, Gianfranco Cicoria, Angelo Infantino, Sara Vichi, Federico Zagni, Domiziano Mostacci
To complete the range of cyclotrons,18 GE introduced the GENtrace (Refs. 19 and 20). This is an extremely compact, sector focused, 7.8-MeV negative-ion cyclotron. The internal ion source allows for irradiation at 35 to 50 µA of one of the three production targets mounted on a short beamline. An interesting feature is that the GENtrace is supplied with a dedicated hydrogen generator for the ion source. The vacuum system is based on a turbomolecular pump. The extraction system has a carousel entirely in graphite to reduce activation, with eight interchangeable stripping foils. The carousel is driven by a piezoelectric driver granting very precise movement and optimal beam control. The footprint of the cyclotron, including its self-shielding, is just 4 × 2.3 m, while it is rated to produce 28 GBq of 18F− in a 2-h irradiation.
A Review of Pellet Injector Technology: Brief History and Recent Key Developments
Published in Fusion Science and Technology, 2020
Shashi Kant Verma, Samiran Shanti Mukherjee, Ranjana Gangradey, R. Srinivasan, Vishal Gupta, Paresh Panchal, Pratik Nayak
An overview of the TSE system is shown in Fig. 9. With the goal of achieving the requirement of continuous fueling, with a frequency of 10 pellets/s, the ETPIS is under development at IPR. It is a cryogenic twin-screw system having intermeshing counter-rotating screws rotating at a temperature less than 11 K. An integrated system is fabricated comprising a twin-screw assembly and heat exchanger components enclosed in a vacuum chamber. The chamber walls are made of Type 304 stainless steel plate. A turbomolecular pump operates in the molecular transport regime to achieve a chamber pressure less than 1E-6 Torr. The screws are rotated using a servo motor. Cooling for the experiment is provided by a cryocooler. The copper barrel of the screw section is cooled by Cryocooler-2 through an oxygen-free high-conductivity copper link. A driveshaft is used to transmit power to the extruder drive screw inside the vacuum chamber.
Development of a high flow rate aerodynamic lens system for inclusion of nanoparticles into growing PVD films to form nanocomposite thin films
Published in Aerosol Science and Technology, 2019
D. Kiesler, T. Bastuck, M. K. Kennedy, F. E. Kruis
The same nanoparticle reactor as used in §4.1 is connected via an array of eight lens systems identical to the one used in Section 4.1 to an arc-PVD coating chamber (Sulzer Metaplas GmbH, Bergisch-Gladbach, Germany), schematically shown in Figure 6. The aerosol flow is equally distributed among the lenses, whereas a single pump having a pumping speed of 600 m3/h (GX600L, Edwards, Burgess Hill, United Kingdom) is used to remove the carrier gas of the eight lens systems. The individual lenses are mounted on a frame which is connected to the access door (with thickness 200 mm) of a commercial PVD chamber having a rectangular size of 600 mm × 600 mm and a height of 1 m. They are placed above each other at different angles pointing towards a stack of stainless steel rings to be coated, which are placed at the center of the PVD reactor. The individual lens systems are aligned using a green DPSS-laser having a power of 10 mW which is inserted at the position of the critical orifice at the inlet. The laser beam then passes through all the lens orifices and allows to predict the exact particle deposition spot at the substrate in the PVD chamber. The individual deposition spots are placed above each other with a distance corresponding to the half-width of the experimentally determined deposition profile (Section 5.1). A number of arc-sputtering sources placed at 90° to the entrance of the lenses into the PVD reactor allow to coat the rotating sampleholder for a stack of cylindrical stainless steel rings, each having a diameter of 150 mm and a height of 1.7 mm. The chamber is connected to a turbomolecular pump (Turbovac T1600, Leybold GmbH) having a pumping speed of 1,600 l/s.