Active Orientation Testbed |
| The active gap tool is a 3 degree of freedom Stewart platform used for alignment studies, and is shown in Figure 1. The template stage is actuated by three actuator legs. Each leg consists of a flexural pin joint, a prismatic joint actuated by a DC servo mike motor, and a flexural U joint connected in series. The three degrees of freedom are translation in the Z direction and rotation about the x and y axes. Piezoelectric actuators can be added to the tip of each actuator to enable finer motion. Stability is provided by a flexure ring that connects the base to the actuator tip. The flexure ring also supplies separation force. |
| There is an air actuated wafer stage to facilitate loading of wafers. The template can be brought close to the wafer (<1 mm gap) and actively aligned parallel to the wafer. Single color interference patterns across the 1 sq. in. imprint area have been achieved. |
| Research is ongoing to automate the alignment process using reflective white light interferometry to measure the gap between wafer and template. Alignment information can also be inferred from imprint force and torque measurements. Data fusion processes are being researched to reduce the uncertainty of gap and alignment measurements. |
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| Figure 1. Active orientation testbed machine. |