DMD Mounting Structure for Phase Interference Uniformity
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Solution Overview
Problem
The convex curvature of digital micromirror devices (DMDs) causes phase interference angle errors, leading to non-uniformity and scan mura on substrates during printing in digital lithography systems.
Innovation Solution
A mount apparatus comprising a mounting frame, interposer, printed circuit board (PCB), force spreader plate, heat sink, and fastener is used to mechanically stress the DMD, improving its flatness and phase interference uniformity by applying controlled forces through a system of screws and deformation bushings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the DMD maintains its convex cylindrical shape, then the device structure is simple and manufacturing is easier, but phase interference uniformity deteriorates causing scan mura on substrates
Solution Approach 1:
The mounting structure is divided into multiple independent components: mounting frame, interposer, PCB, force spreader plate, heat sink, and fasteners. Each component performs a specific function, allowing the complex task of flattening the DMD to be achieved through coordinated action of segmented parts rather than a single complex structure
Solution Approach 2:
The interposer acts as an intermediary component between the mounting frame and the DMD. It provides a flat contact surface that interfaces with the convex DMD surface, while the force spreader plate serves as another intermediary that distributes mounting forces evenly across the DMD surface, enabling phase interference uniformity without requiring direct complex contact
2Manufacturing precision
If contact pads apply force to flatten the DMD, then phase interference uniformity improves, but stress concentration may damage the DMD
Solution Approach 1:
The force application is made non-uniform in a controlled manner: the interposer provides broad distributed contact across the DMD surface, while the force spreader plate further distributes localized forces from multiple fasteners. This creates locally optimized stress distribution that achieves overall flatness without concentrating damaging stress at any single point
Solution Approach 2:
The mounting structure incorporates compliant elements and distributed force paths that cushion and distribute applied forces before they reach the DMD. The interposer and force spreader plate act as cushioning layers that prevent direct transmission of concentrated fastener forces to the fragile DMD structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly improves phase interference uniformity across the DMD, reducing scan mura by 75% to 85%, enhancing printing performance.
Implementation Method 1
mechanically stressing the device package
Implementation Method 2
adjusting a flatness of the DMD
Implementation Method 3
a heat sink operable to be in contact with the force spreader plate
Implementation Method 4
an interferometer to determine whether the flatness of the DMD meets a flatness criterion
Data Source
AI summary
Embodiments of the present disclosure relate to mount apparatuses for digital micromirror devices of digital lithography systems and methods of mounting the digital micromirror devices. The mount apparatuses described herein retain spatial light modulators, such as DMDs. The mount apparatus enables the flattening of the DMD by providing a force such that the pair of contact pads contact the DMD. The DMD is positioned in a mounting frame of the mount apparatus. Contact pads of the mounting frame are operable to apply pressure to the DMD.