Dynamic Exposure Model of Scanning Beam Interference Lithography

To obtain desired photoresist grating by scanning beam interference lithography (SBIL), a precise exposure dose is demanded. For it is difficult to apply the real-time exposure monitoring technology in SBIL, a precise dynamic exposure model is needed to predict the groove profile of the photoresist grating. In this paper, a novel dynamic exposure model is established based on the characteristics of SBIL. Considering the nonlinear properties of the photoresist, a three-dimensional development process simulation is conducted based on cellular automata (CA) model. Based on this model, the influence mechanism of exposure parameters on groove profile can be analyzed, which provides an effective analysis method for optimizing exposure parameters of SBIL.

Yaw error correction of ultra-precision stage for scanning beam interference lithography systems

The stage yaw error is a key factor affecting the phase distortion of gratings produced by scanning beam interference lithography system. In order to solve this problem, a coarse-fine dual-stage mechanism is proposed, in which an ultra-precision fine positioning stage with yaw error correction function is developed. To achieve nanoscale positioning and sub-microradian yaw motion accuracy, four Lorentz motors are used to drive the fine stage. The internal coupling factors and the mechanism of Lorentz motors motion control are analyzed. Besides, the Abbe error caused by the yaw error is investigated. Positioning and scanning experiments are conducted and the outcomes show that maximum yaw error is 0.33 μrad during constant velocity scanning, which completely meets the grating fabrication requirements.