Direct drives position wafers and exposure masks in semiconductor production with high precision within one plane. To enable objects to be lifted with nanometer precision over an area of more than only a few square millimeters, IMMS had already developed a 6D direct drive with partners. This can raise and lower objects through 10 mm under active control with nanometre precision in a travel range of 100 mm diameter in the plane.

Larger vertical movements limit precision and movement dynamics up to now

The requirements from industry do not only concern horizontal movements (x,y), in order to be able to structure and position surfaces and structures of millimetre or centimetre sized products with nanometre precision. Increasingly large vertical movements are to be carried out at the same time. The 6D direct drive works with electromagnetic vertical drives (z). The higher objects are lifted with it, the greater the distance between the x-y drive coils, which are fixed to the frame, and the magnetic coils in the slider, which are required for the horizontal precision movements. Even a small amount of lifting drastically reduces the efficiency of the x-y drive system, multiplying power losses and thereby limiting the achievable motion dynamics due to thermal effects.

New vertical tracking elements increase stroke distance

To overcome these hurdles, IMMS worked on concepts for new components in the K4PNP+Z project, with which the x-y drive coils, which have been fixed to the frame up to now, are now can be vertically tracked for a larger stroke and thus kept close to the magnets in the slider. These vertical tracking elements were built, integrated into the overall system and experimentally investigated. Likewise, the vertical drive units for the higher travel distances and for higher payloads were designed and tested. With this solution, z-strokes up to 25 mm with lateral travel ranges (x-y) over diameters of 200 mm can be reached.