22 October 2014

HepcoMotion’s vacuum-grade bearings and vee slides used for Riber’s latest MBE systems

HepcoMotion says that its vacuum-grade bearings and slides are being used by Riber S.A. of Bezons, France, which manufactures molecular beam epitaxy (MBE) systems as well as evaporation sources and effusion cells, in its latest systems.

Replacing an in-house unit, HepcoMotion’s solution allows Riber to set the system pre-load without any play in the mechanism, ultimately providing much improved repeatability with a level of reliability not previously seen, it is claimed.

The MBE process requires wafers to be positioned accurately within a high-vacuum chamber. This highlights challenges with respect to accuracy and smoothness of motion, with the added complication of the need to work at a pressure of 10-9mbar. Standard vacuum-compatible systems often only work under conditions reaching 10-6mbar, says HepcoMotion.

Picture: HepcoMotion’s vacuum-grade bearing.

When Riber needed to source a replacement positioning system, it turned to HepcoMotion and its size 34 vacuum bearings. These complete stainless-steel products were already proving successful in vacuum applications up to 10-6mbar, says HepcoMotion. To achieve the higher-vacuum suitability demanded, the firm used a special vacuum grease within the sealed bearings, allowing the product to operate at higher vacuum for extended process periods without fear of breakdown.

In wafer transfer operations, the length of travel can vary, however Riber’s standard solution calls upon flat SL2 slides (SSM44 x 1000mm long) with two VACSS SJ34C bearings and two VAC SSSJ34E bearings fitted into a special carriage, with the rack/pinion providing the drive solution. The configuration has been optimized to furnish Riber with an easy-to-install package.

HepcoMotion says that Riber now has a highly reliable solution with the opportunity to vary the frictional resistance to suit the application load and to maintain a high level of accuracy. A low-friction system is vital if fretting corrosion is to be avoided where stainless steels are running together effectively dry. Any contamination within the chamber would compromise the process, leading to a loss of wafers. HepcoMotion says that its vee guide has been able to provide the level of confidence needed by Riber to satisfy this specialist application.

Tags: Riber MBE

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