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VACUUM
(GENERATION AND MEASUREMENT)
Vacuum is vital for today's research and high-tech industries.
Vacuum is measured using a large variety of gauges and the results are expressed in units of pressure:
< p >SI = 1Pa(Pascal) = 1N/m2.
Of larger usage in the vacuum field are two derivative units:
1 torr = 1 mm Hg (1 torr = 133.322 Pa), and
1 mbar = 10-3 Kgf/cm2 = 102 Pa
Vacuum is produced using VACUUM PUMPS. Different types of pumps cover required levels of vacuum; here are mentioned few types:
Mechanical (piston, vane, roots - rotary) pumps, for low and medium vacuum (1000 to 1 mbar, and 1 to 10-3 mbar respectively)
-Turbomolecular pumps, covering high vacuum (HV) 10-3 - 10-7 mbar and ultra high (UHV) below 10-7 mbar.
Vacuum is accurately measured with vacuum gauges, usually covering 2-5 orders of magnitude in vacuum pressure. Some gauges are multi-channel covering all ranges of interest – from 1000 mbar (atmospheric
pressure) to 10-7 mbar, enough for most applications.
We present below a schematic of Kurt J. Lesker RF Sputtering Metal Deposition System. It requires 6 x 10-6 torr of vacuum then Argon is purged into the chamber to 10-1 torr
when RF Plasma is ignited. For deposition pressure is reduced to 5 x 10-2 torr.
These two pressure levels, mentioned above, are controlled by adjusting opening of main valve (MV) and the Argon needle valve (NV).
Cooling System (water) should be Open all the time the Turbomolecular Pump (TMP) is ON. Like for any high vacuum system detailed instructions are necessary when operating this equipment.
MP - Mechanical Pump;
TMP - Turbomolecular Pump;
MChVG - Multi-channel Vacuum Gauge;
RFG - Radio Frequency Plasma Generator;
TC - Temperature Controller;
QL - Quartz Lamp, S - Sample, Sh - Shutter;
NV - Needle Valve, TV1 - Toggle Valve (controls Argon flow);
MV - Main Valve (controls vacuum when Argon is purged in);
TV2 - Toggle Valve (vent), F - Filter;
WCS - Water Cooling System;
PR, L/H - Pressure Regulator with its Low and High Gauges;
Ar, Cyl - Argon Cylinder
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