4.6.5 Harsh process chemistry
The ongoing development of processes especially in the semiconductor and solar industry places constantly new demands on the vacuum pumps used. Based on the proven technology of multi-stage Roots pumps, Pfeiffer Vacuum provides the perfect solution for demanding processes in these industry sectors with its H series. The gas throughput at the process pressure, the particle tolerance and the resistance to condensation have been significantly increased in comparison with previous pump solutions.
As with the P (for Process) series pumps, H series (for Harsh Process) pumps are equipped with a temperature control and an inert gas flushing system. The parameter range for optimizing adjustment to the process is far wider, however, than in pumps in the P series.
Figure 4.14: A 203 H cross-section
This pump series is based on the A 203 H dry-running process pump. We have taken three additional models from the series and supplemented them with Roots pumps for enhanced pumping speeds and gas throughput in the process pressure range. Due to the use of specific materials, the corrosive gas equipment of these pumps also makes it possible to use strong oxidizing agents such as NF3. The broad temperature range of the pumps enables them to adapt to widely differing processes such as tungsten deposition at low temperatures or nitride deposition at high temperatures. A highly efficient motor results in energy savings at low pressures and provides good startup properties after pump downtime due to its high torque.
Figure 4.15: A 1503 H process pumping station
The models in the A3H series are ideally compatible with pumps in the P series thanks to their identical interfaces and identical media connections. This means that if a process is changed on an existing production plant, optimized pump solutions can be obtained with a minimum of installation work by exchanging the pumps.
Supplementing the A 1803 H model with a third Roots stage provides a compact and extremely powerful pumping station with maximum pumping speeds for CVD processes. The AD 73 KH uses a frequency- controlled Roots pump with a rated pumping speed of 4,500 m³ · h-1 in its own frame over the dry-running process pump. Installation is easy due to the modular structure and the various pumps in the pumping station can be taken out singly and maintained in the event of servicing work. The frequency converter of the Roots pump on the intake side allows adjustment to the process parameters over a broad gas throughput range and for widely differing process gases.
Pfeiffer Vacuum monitors the dynamic development of processes in the various sectors of industry on an ongoing basis and will continue in the future to deliver optimized pump solutions to meet these requirements. An initial overview is given in Chapter 8, Contamination Management Solutions.