The positioning experts at August Steinmeyer have developed ball screws for use in ultra-high vacuum. These are used in a universal series of linear stages for a new type of imaging process with 30 nm resolution. This required several positioning systems for extreme standstill stability of 10 nm. A ball screw drive makes the positioning technology particularly stable and precise - and, depending on the design, also fast and durable. The systems were used at the Paul Scherrer Institute (PSI), where they fully met the demanding expectations. The technology covers a wide range of applications: from research to medical technology to semiconductor technology.
"Positioning in a vacuum is a special challenge and requires suitable materials, components and lubricants," explains Elger Matthes, Head of Product Management at Steinmeyer Mechatronik GmbH, the competence centre for positioning systems in the Steinmeyer Group. The company has developed a range of new positioning systems for demanding vacuum applications under UV, HV, UHV and also EUV, which are suitable for a pressure range of up to 10-11 mbar and a maximum bake-out temperature of 120°C. Also, due to the very low outgassing and particle poverty, the requirements for use under extreme ultraviolet radiation are met. The axes are available in sizes LA80, LA95, LA170 and are designed for loads up to 20 kg in vertical operation. Stroke lengths of up to 500 mm are offered with a particularly fast transport axis for sample feeding. An advantage is that ball screws can be combined with a robust stepper motor drive, which can optionally also be operated with µm feedback by means of a linear scale. Elger Matthes emphasises: "Fortunately, we have the necessary competence for these tasks in our group of companies for a special development of the ball screw."
Ball screw from August Steinmeyer
An essential component of the linear tables is a special ball screw drive, on the one hand to move dry unusually fast for vacuum (up to 50 mm/s) and with a previously unattained service life of up to 5 km. When ultra-high vacuum lubricants are used, the achievable service life increases to several 100 km. At higher partial pressures up to 10-6 mbar, distances of several 1000 km can also be achieved in vacuum due to the better lubricants and more durable materials available for this range. The component was developed by August Steinmeyer GmbH & Co. KG. "With ceramic balls, a coating of the raceways, a special thread grinding process as well as an optimised deflection, good running properties of the ball screw can be achieved even without lubrication," explains Wolfgang Klöblen, head of development at August Steinmeyer.
In addition to the individual material selection and vacuum lubrication, the positioning system from Steinmeyer Mechatronik can optionally be equipped with a piezo caliper brake to ensure stability in the nanometre range despite high loads. In addition, adaptations to the installation situation in the chamber enable an individual customer bore pattern, specific adapter parts and cable guides ensure a solution tailored to the customer's needs.
Wide range of applications
Applications include semiconductor manufacturing, where the positioning systems can be used in processes with extreme ultraviolet radiation, such as beam shaping for exposure processes as well as surface analysis and sensor positioning. In mass spectrometry, they can be used to identify elements or molecules for active ingredient compositions or to detect warfare agents. In OLED manufacturing, they can be used for coating processes as well as layer thickness and layer rate measurements. Further areas of application can be found in the optical industry, in basic research as well as in laboratory technology and analytics.