Through-wall maglev stage

Internal research

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An in-house developed vacuum compatible through-wall actuator in 6 Degrees of Freedom.

High precision machines such as EUV wafer scanners and E-beam measurement systems require a high vacuum level. Contamination of this vacuum due to moving cables and bearings of the positioning stages within are an issue. An inverted planar motor solves this contamination issue but leads to a complex system due to position dependent commutation and a large number of coils. Therefore an alternative stage design is made at MI-Partners which has a low degree of complexity and does not cause contamination of the vacuum.

In this concept a separation has been made between two vacuum levels: a clean/precision vacuum and a non-precision/dirty vacuum. The separation between the two is realized by a wall. The design uses a Short Stroke-Long Stroke (SS-LS) stage configuration where the SS stage makes its actuation forces through the wall. The precision vacuum contains the SS chuck carrying a wafer for manufacturing or inspection. In the non-precision vacuum a conventional stacked LS XY stage is placed. The function of this XY stage is to enable a larger stroke for the short stroke system. The vacuum underneath the separator plate is only required to minimize loads on the wall due to the pressure difference over a large area.

Click here for the video.

Challenges

  • Generating actuation forces through a wall

  • Actuator development

  • Low stiffness gravity compensation

Key Competences

  • Innovative Concept Design

  • Electromagnetic actuator design

  • Over-actuated Control

Results

  • Novel vertical actuators with included low stiffness gravity compensation (<1 N/mm)

  • In plane actuators capable of actuating through the wall

  • High bandwidth for flexible chuck

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