Piezo-Actuated Mirror Resist Mask Etching
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Solution Overview
Problem
The existing methods for manufacturing mirror devices with piezo-actuated mirrors face challenges in forming precise resist masks due to the height differences caused by the piezoelectric elements, leading to difficulties in photolithography conditions and subsequent etching processes, which affects the accurate formation of actuator bodies and mirrors.
Innovation Solution
A method involving a substrate with an insulation layer where the piezoelectric element is formed on the actuator body portion, with specific etching processes and resist mask configurations to ensure precise formation of both the actuator body and mirror portions, including the use of first and second slits in the resist mask with different widths to control etching and mask formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a resist mask is formed on a substrate with a piezoelectric element, then the resist mask can cover both the actuator body portion and mirror portion, but the height difference caused by the piezoelectric element makes it difficult to set photolithography conditions
Solution Approach 1:
The patent applies different etching conditions to different regions: first etching conditions for removing the insulation layer in the mirror region, and second etching conditions for removing the insulation layer in the actuator body region. This local differentiation allows precise control of the resist mask formation despite the height difference caused by the piezoelectric element.
Solution Approach 2:
The etching process is divided into two separate steps: first etching the insulation layer in the mirror region, then etching the insulation layer in the actuator body region. This segmentation allows each region to be processed with optimized conditions, resolving the contradiction between covering both regions and maintaining manufacturing precision.
2Manufacturing precision
If strong photolithography conditions are used to remove resist in thicker portions, then the resist completely dissolves in thick portions, but the resist excessively dissolves in thinner portions
Solution Approach 1:
The patent uses different etching conditions for different regions to achieve complete resist dissolution in thick portions without excessive dissolution in thin portions. The first etching conditions are optimized for the mirror region while the second etching conditions are optimized for the actuator body region, allowing precise control of resist removal.
3Ease of manufacture
If a single etching process is used for both actuator body and mirror portions, then the process is simple, but the peripheral portions cannot be precisely formed due to height differences
Solution Approach 1:
The etching process is segmented into two distinct steps: first etching the insulation layer in the mirror region with first etching conditions, then etching the insulation layer in the actuator body region with second etching conditions. This segmentation enables precise formation of peripheral portions while maintaining manufacturing efficiency.
Solution Approach 2:
Different etching conditions are applied to different regions: the first etching conditions are optimized for removing insulation layer in the mirror region, while the second etching conditions are optimized for the actuator body region. This local quality approach ensures precise peripheral portion formation.
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 allows for the precise formation of both actuator bodies and mirrors, reducing the need for strong photolithography conditions and ensuring accurate etching, thereby improving the yield and reducing size and light loss in the mirror device.
Implementation Method 1
an actuator in the mirror device is piezo-actuated, and has an actuator body and a piezoelectric element formed on the actuator body
Implementation Method 2
first removing a portion of the insulation layer located in a second region including at least one portion to be the mirror by etching
Data Source
AI summary
A portion of an SiO2 layer 240 on a peripheral portion 255 of an actuator body portion 251 is left on the surface of the actuator body portion 251 when it is etched so as to extend over the outside of the piezoelectric element 4. When the third resist mask 330 covering the actuator body portion 251 and the mirror portion 252 is formed and etching is performed, the third resist mask 330 has a first slit 331 and a second slit 332, the second slit 332 exposing a peripheral portion 256 of a mirror portion 252, and the first slits 331 exposing a peripheral portion 256 of the actuator body portion 251 and a portion of the SiO2 layer 240 on the actuator body portion 251, and having a width wider than the second slit 332.