Conductor & Polysilicon Etch

Dry conductor etch process consists of selectively removing conductor materials (aluminum, tungsten,...) on the wafer, shaping the electrical interconnections of a semiconductor device. Dry Polysilicon (Poly-Si) etch consists of selectively removing Polysilicon to create the transistor gate. As critical dimensions are continuously shrinking, high uniformity and selectivity are needed to meet required electrical performance on such tiny structures: this is achieved by Plasma or Reactive Ions etching process.

Application requirements

  • Vacuum performance stability over time for optimized yield
  • Condensable management by high temperature operation
  • Corrosion resistance by advanced coating technology
  • High process lifetime at low operating costs: Low power consumption, low repair cost
  • High capacity & high flow magnetically levitated turbopumps
  • Small footprint dry pumps

How does it work?
Etching gas, commonly Chlorine or Fluorine based, are injected in the reactor. Plasma generates radicals which react on the wafer surface by creating a volatile by-product. Thanks to device patterning obtained by lithography and through control of plasma reaction and temperature, the material is selectively etched from the surface at the desired rate.

Vacuum requirements
Dry conductor & Poly-Si etch processes operate at low pressure, in the range of 10-2 to 10-3 mbar. In order to maintain a low vacuum, turbopumps are mounted directly on the chamber reactor, backed by primary dry pumps installed in the basement. As gas flows are continuously increasing, required turbopumps pumping capacity vary from 1,600 to 3,000 l/sec on the newest generation reactors. Dry pumps typically require pumping speeds from 600 to 1,200 m3/h.

By-products to be evacuated are condensable and highly corrosive. This represents a great challenge for vacuum pumps, which should be able to operate at high temperature under a very corrosive environment.

Product portfolio
Pfeiffer Vacuum provides a full range of turbopumps and primary dry pumps designed to handle these challenges. Our magnetically levitated turbopumps provide vibration free high vacuum and high temperature / high flow operation. Featuring optional corrosion resistance, our ATH M series are qualified at major OEMs on the most advanced conductor & Poly-Si etch chambers. Our A3XN or A4XN dry pumps feature advance materials to withstand corrosion & sophisticated thermal management to prevent deposition, for long lifetime & low operating costs.

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