# NPS6D200--A Long Range Nanopositioning Stage with 6D Closed Loop Control
## 2 State of the Art  
Ongoing international research investigates the realization of nanopositioning devices for high-precision measurement machines as well as for sub-10 nm fabrication solutions. In such applications, the high-precision positioning stages are applied to move the sample with respect to the tool, and they must provide nanometer stability and sensitivity. Refs. [4; 5; 6; 7; 8; 9; 10; 11; 12] describe research work and realized machines for small operating ranges. However, in the context of this paper, we focus on the challenges of long-range nanopositioning and understand \"long range\" to mean stages with a planar travel range of at least 50 mm \(\times\) 50 mm. Despite the large dimensions, these positioning systems are required to allow for deterministic and reproducible step and trajectory movement at the nanometer scale. Thereby, the basic stage architecture plays a crucial role in obtaining the necessary controllability and thus achieving single-digit nanometer servo errors in closed-loop control. Among others, this is one important aspect covered by the set of general design principles for precision engineering solutions [13; 14; 15; 16].  
Due to the varying requirements and boundary conditions, a variety of long-range nanopositioning stage concepts can be found in literature [17; 18; 19; 20; 21; 22; 23; 24; 25]. To achieve multiaxial motion, many solutions provide parallel kinematics with a combination of linear Lorentz actuation and linear roller or air guidings, respectively. The wedge-type approach in [22], the NanoCMM [21] and the high-precision 3D CMM [20] are exemplary for this and illustrate the efforts to avoid the serial kinematics of stacked linear axes and to comply with the mentioned design principles. Towards this end, the integrated direct drive approach, where the \(xy\)-driving forces directly act on the moving part [26]; shows distinct advantages, especially in combination with a planar air guiding of the moving part. While this approach is in focus of our own research work [27; 28], [PERSON] [17], and [PERSON] [24] also describe long-range nanopositioning solutions based on this approach. At TU Ilmenau, as a follow-up of the classical stacked approach for a small range in the NMM-1 [29; 30], the long-range machine NPMM-200 was developed [31], which also applies a planar direct drive, here in combination with stacked linear roller guidings. While these contributions demonstrate the suitability of such machines to measure 3D objects with the highest precision, [32; 33; 34] show how the machines can be utilized to develop and investigate novel solutions in sub-10 nm fabrication research.  
The nanofabrication machine (NFM-100) was developed by combining the research activities of IMMS, TU Ilmenau, and SIOS GmbH and [35; 36; 37] illustrate the positioning capabilities of the contained planar direct drive as well as the beneficial combination with a cantilever based probing system. Where the NFM-100 provides a pure planar positioning in \(\diameter 100\,\mathrm{mm}\), the \"Integrated Planar 6-DOF Nanopositioning System\" [38] represents a first demonstrator solution to implement vertical actuation in combination with such a directly driven planar stage for a motion range of \(\diameter 100\,\mathrm{mm}\)\(\times\)\(10\,\mathrm{mm}\) (planar \(\times\) vertical). In subsequent research work we developed the NPS6D200 for a travel range of \(\diameter 200\,\mathrm{mm}\)\(\times\)\(25\,\mathrm{mm}\), which is the subject of this paper.