Flow Through MEMS Package for Spatial Light Modulator Contamination Control
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Solution Overview
Problem
Conventional MEMS spatial light modulators in maskless lithography systems face issues with high power lasers volatilizing contaminants, leading to reduced reflectivity and operating life due to unsatisfactory hermetic sealing and evacuation methods.
Innovation Solution
A flow through MEMS package design that includes a cavity with an inlet and outlet for fluid flow, typically using gases like nitrogen, to maintain a controlled environment and prevent contaminant buildup on reflective surfaces, with fluid flow rates ranging from 0.01 to 10000 sccm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hermetic sealing and evacuation methods are used to protect MEMS from contaminants, then the MEMS package is sealed and protected, but contaminants still build up on surfaces reducing reflectivity and operating life
Solution Approach 1:
The patent introduces a flow-through package design that maintains an inert atmosphere (such as nitrogen or other protective gases) continuously flowing over the MEMS reflective surfaces. This inert environment prevents oxidization and chemical reactions between contaminants and the MEMS surfaces, thereby reducing contaminant buildup and extending operating life while addressing the limitations of hermetic sealing alone
2Power
If high power lasers are used to operate spatial light modulators, then light modulation capability is improved, but lasers volatilize contaminants that build up on SLM surfaces reducing reflectivity
Solution Approach 1:
The patent implements continuous flow of protective gas through the package during laser operation. This continuous action ensures that as high power lasers operate and volatilize contaminants, the flowing inert atmosphere continuously sweeps away vaporized materials before they can condense and build up on the SLM surfaces, maintaining reflectivity throughout extended operation
Solution Approach 2:
The patent introduces protective gas (such as nitrogen) as an intermediary medium between the high power laser and the MEMS surfaces. This intermediary atmosphere acts as a buffer that prevents direct interaction between laser-generated contaminants and the reflective surfaces, reducing reflectivity loss while allowing high power operation to continue
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 flow through MEMS package effectively minimizes reflectivity-reducing deposits, extending the operational life of spatial light modulators by continuously purging contaminants and maintaining a clean environment, as shown by reduced carbon and silicon deposition compared to conventionally packaged SLMs.
Implementation Method 1
an inlet through which a fluid is introduced to the cavity during operation of the MEMS and an outlet through which the fluid is removed during operation of the MEMS
Data Source
AI summary
A flow through Micro-Electromechanical Systems (MEMS) package and methods of operating a MEMS packaged using the same are provided. Generally, the package includes a cavity in which the MEMS is enclosed, an inlet through which a fluid is introduced to the cavity during operation of the MEMS and an outlet through which the fluid is removed during operation of the MEMS, wherein the package includes features that promote laminar flow of the fluid across the MEMS. The package and method are particularly useful in packaging spatial light modulators including a reflective surface and adapted to reflect and modulate a light beam incident thereon. Other embodiments are also provided.