Solid Micromirror Support Structure for DMD Fill Factor
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Solution Overview
Problem
Conventional digital micromirror devices (DMDs) face challenges in achieving a homogeneous micromirror surface without increasing production costs or process steps, which affects optical performance and reliability due to the hollow opening created by micromirror support posts.
Innovation Solution
A method involving a sacrificial layer and selective removal to form a substantially solid micromirror support structure with increased conductive sidewall thickness, enhancing structural rigidity and conductivity, while maintaining a flat outer surface to increase the fill-factor ratio and minimize stray reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional micromirror support posts are used, then the micromirror can be supported, but a hollow opening is created that reduces the fill-factor ratio and increases stray reflections
Solution Approach 1:
The invention extracts and removes the hollow opening from the micromirror support structure by using a sacrificial layer that is completely removed after forming the support posts. This eliminates the harmful hollow space that causes stray reflections and reduces the fill-factor ratio, while still providing the necessary mechanical support for the micromirror.
Solution Approach 2:
The sacrificial layer acts as an intermediary material that temporarily occupies the space where the hollow opening would form. By removing this intermediary layer, the support structure becomes solid without requiring the hollow opening, thus eliminating stray reflections while maintaining structural integrity.
2Strength
If the micromirror support structure is made solid, then structural rigidity is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The sacrificial layer is deposited and patterned in advance before forming the micromirror support posts. This preliminary action creates a template that guides the subsequent formation of solid support structures, eliminating the need for complex post-processing steps to achieve solidification while maintaining manufacturing simplicity.
Solution Approach 2:
The invention changes the material parameter by using a sacrificial layer that can be completely removed, transforming the support structure from hollow to solid. This parameter change achieves enhanced structural rigidity without adding significant manufacturing complexity, as the removal step is a standard process in the fabrication sequence.
3Reliability
If the fill-factor ratio is increased, then the contrast ratio is improved, but the micromirror surface homogeneity may be compromised
Solution Approach 1:
The invention ensures homogeneity by using a uniform sacrificial layer that is completely removed across the entire micromirror surface. This creates a homogeneous solid support structure without variations in thickness or composition, maintaining surface uniformity while maximizing the fill-factor ratio for improved contrast.
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 enhances the contrast ratio of DMDs by increasing the fill-factor of reflective surfaces, improves structural rigidity, and maintains the same number of process steps as conventional DMD processing, thereby improving optical performance and reliability.
Implementation Method 1
selectively removing a portion of the sacrificial layer to form at least one micromirror support
Implementation Method 2
A vast array of semiconductor devices utilize physical vapor deposition (PVD) techniques in conjunction with deep ultraviolet (DUV) photolithography
Implementation Method 3
DUV is used for very fine resolution photolithography, a procedure where a chemical known as a photoresist is exposed to UV radiation which has passed through a mask. The light allows chemical reactions to take place in the photoresist
Data Source
AI summary
Methods and apparatus for use with a micromirror element includes a micromirror a micromirror having a substantially flat outer surface disposed outwardly from a support structure that is operable to at least partially support the micromirror. The support structure includes at least one layer overlying at least two discrete planes that are both substantially parallel to the outer surface of the micromirror. In one particular embodiment, the support structure includes annular-shaped sidewalls that encapsulate a photoresist plug.