4.6.2 Application
Advantages of multi-stage Roots pumps in a corrosive gas version include:
- Ideal adjustment to the vacuum process concerned by adjusting the temperature, the purge gas throughput and the rotation speed.
- No lubricant in the gas displacement area
- No operating fluid disposal problems
- High reliability and system uptime
- Long service intervals, low power consumption and media consumption of cooling water and flushing gas, and low cost of ownership as a result
- Small footprint, with good integration and savings in cleanrooms and pump levels
- Extensive controlling options, local or remote control, integration in a monitoring network
- Minimal leak rate
- Ideal backing pump for turbopumps and Roots pumps in corrosive processes
- Certified to UL/CSA and SEMI S2
Dust and particles
Process pumps are exposed to particles that are conveyed to the pump from process chambers and fore-vacuum lines. In addition, particles and deposits that may result from the condensation of reaction byproducts in the pumps themselves must also be tolerated. Ideally, it is possible to avoid the formation of particles and deposits by using adjustable heating and controlled temperature patterns. By pumping in a vertical direction, any particles drop out of the pump stage and remain in the outfall channel to the next stage. After the next ventilation and the subsequent pump-down, the particles will be discharged by the displaced gas into the next stage that follows. This discharging mechanism expels more than 98 % of the particles generated from the inlet to the outlet. This means that a central exhaust gas cleaning system which captures and disposes of not just process chemicals but also particles can be provided at the pump outlet. High-maintenance traps and filters on the intake side can be avoided wherever possible in vacuum solutions for corrosive, toxic and condensable media.
Corrosive gases
Multi-stage Roots pumps of the P and H series are specially designed for corrosive gas processes in the semiconductor, solar and coating industry for flat screens. Both the metal rotors and stators as well as the elastomer materials of the pumps are made of highly corrosion-resistant materials.
Leakage rate
The high tightness and the protection from gases diffusing back from the ambient air or an exhaust gas cleaning system or scrubber through a non-return valve make multi-stage Roots pumps the perfect solution for corrosive gas applications. Encapsulated motors are also part of the anti-leak concept.
