Micromirror Arrays with Dielectric Multilayers for Maskless Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The photolithography industry faces challenges with contact printing methods due to mechanical contamination, high costs and non-uniform illumination in projection methods, and limited material ablation in laser ablation methods, particularly for large-scale substrate fabrication, leading to inefficiencies and increased costs due to the need for multiple photomasks and frequent replacements.
Innovation Solution
The implementation of maskless lithography technology using micromirror arrays with a polymeric mirror base and a reflective dielectric multilayer for selective illumination of substrates, allowing pattern fabrication without photomasks, and enabling large-area patterning with high reflectivity and adjustable micromirror positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If contact printing methods are used for photolithography, then the process is simple and direct, but the mask becomes contaminated by photoresist leading to undesired patterns and requiring frequent mask replacements
Solution Approach 1:
The invention extracts and removes the photomask from the lithography system, replacing it with a maskless spatial light modulator that uses an array of mirrors to selectively reflect light. This eliminates the contamination problem entirely since there is no physical mask contacting the photoresist-coated substrate.
Solution Approach 2:
The mechanical contact-based mask system is replaced with an optical control system using spatial light modulators and mirror arrays. The pattern selection is achieved through electronic control of mirror orientations rather than physical mask contact, substituting mechanical interaction with optical field control.
2Reliability
If projection imaging methods are used to avoid mask contamination, then the process becomes non-contact, but the system cost increases significantly due to large and expensive optical components
Solution Approach 1:
The continuous optical field is segmented into discrete controllable elements through the mirror array, where each mirror or group of mirrors can be independently controlled to define specific pattern regions. This segmentation allows complex patterns to be built from simple, inexpensive individual mirror elements rather than requiring a single complex optical system.
Solution Approach 2:
The invention adds the dimension of temporal sequencing to the lithography process, using a digital micromirror device that can rapidly switch between different mirror orientations to project different pattern segments at different times. This allows a single inexpensive optical channel to replace multiple expensive simultaneous projection channels.
3Area of stationary object
If large-area substrates are patterned using projection methods, then the coverage area increases, but the illumination uniformity deteriorates due to misalignment and stitching problems
Solution Approach 1:
The invention uses a master pattern stored in digital memory that can be repeatedly copied and projected onto the substrate through the mirror array. This digital master ensures perfect reproduction of the same high-precision pattern across the entire substrate area without the accumulation of alignment errors that plagues multi-step projection methods.
4Reliability
If photomasks are used for pattern fabrication, then the process is established and reliable, but the production cost increases due to the need for multiple masks and frequent replacements
Solution Approach 1:
The invention changes the fundamental parameter of pattern definition from physical mask geometry to digital data representation. Patterns are stored as digital information in memory and controlled through electronic signals to the mirror array, allowing infinite pattern variations without physical mask fabrication, thus eliminating mask-related costs.
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
This approach reduces production costs by eliminating the need for photomasks, improves uniformity and efficiency in substrate patterning, and allows for flexible and high-intensity illumination without damaging the micromirror structures, enhancing the quality and speed of pattern generation.
Implementation Method 1
a reflective dielectric multilayer disposed over the polymeric base... The reflective dielectric multilayer has a reflectivity greater than 90%, 95% or 98% for at least a portion of electromagnetic radiation
Implementation Method 2
controlling a position of each micromirror element of the array such that electromagnetic radiation from the source is reflected from each micromirror element to a location either on or off of the substrate
Implementation Method 3
A micromirror of this aspect comprises a polymeric mirror base having an exposed surface area... allowing for flexible and high-intensity illumination without damaging the micromirror structures
Data Source
AI summary
Micromirrors and micromirror arrays described herein are useful, for example in maskless photolithography systems and methods and projection display devices and methods. According to one aspect, the micromirrors comprise a polymer structural layer and a reflective dielectric multilayer for selective reflection and/or redirection of incoming electromagnetic radiation. According to another aspect, incorporation of a reflective dielectric multilayer allows for use of polymer structural materials in micromirrors and prevents damage to such polymer materials due to excessive heating from absorption of electromagnetic radiation, as the reflective dielectric multilayers are highly reflective and minimize heating of the micromirror components. According to yet a further aspect, top down fabrication methods are described herein for making a micromirror comprising a polymer structural layer and a reflective dielectric multilayer.