Optical Movable Structure Rib Etching for Deformation Control
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Solution Overview
Problem
Existing methods for manufacturing optical devices with rib portions on movable units or elastic support portions struggle with accuracy, leading to deformation issues and difficulties in forming these features with precision.
Innovation Solution
A method involving a semiconductor substrate with a first and second semiconductor layer and an insulating layer, where the rib portion is formed using a two-stage etching process with resist layers, ensuring the rib portion is thinner than the base layer, allowing for precise formation and preventing protrusion, thereby maintaining the structural integrity and accuracy of the optical device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rib portion is provided to suppress deformation of the movable unit or elastic support portion, then the structural stability is improved, but the manufacturing accuracy deteriorates due to difficulty in forming the rib portion with precision
Solution Approach 1:
The etching process is segmented into two distinct stages: a first etching step that creates a depression to a first depth, and a second etching step that forms the rib portion to a second depth. This segmentation allows each etching step to be independently controlled, thereby achieving both the structural stability provided by the rib portion and the manufacturing accuracy required for precise formation.
Solution Approach 2:
The first etching step performs a preliminary action by creating a depression in the semiconductor layer before the second etching step forms the final rib portion. This preliminary depression serves as a precursor structure that guides the subsequent etching process, enabling accurate rib portion formation while maintaining structural integrity.
2Stability of the object's composition
If the rib portion is made thinner to prevent protrusion from the base, then the structural integrity is maintained, but the ability to suppress deformation deteriorates
Solution Approach 1:
The semiconductor layer is given different local qualities through selective etching: the rib portion is etched to a second depth while the base remains at a first depth, creating a thickness difference. This local quality variation allows the rib portion to be thinner (preventing protrusion and maintaining structural integrity) while still providing sufficient strength to suppress deformation through its strategically positioned structure.
Solution Approach 2:
The solution transitions from considering only the horizontal dimensions to incorporating the vertical dimension by creating a stepped structure with different etching depths. This dimensional change allows the rib portion to be positioned at a different depth level than the base, enabling it to prevent protrusion while maintaining structural integrity through its elevated position.
3Manufacturing precision
If a two-stage etching process is used to form the rib portion with accuracy, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The two-stage etching process merges multiple functions into a single integrated process: the first etching step creates both a depression and serves as a mask for the second step, while the second etching step forms the rib portion using the depression as a guide. This merging of functions reduces the need for separate masking and etching operations, thereby improving manufacturing precision without proportionally increasing device complexity.
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 method enables the accurate formation of rib portions, suppressing deformation and ensuring the optical device's components move correctly, enhancing the device's controllability and preventing damage during transportation or movement.
Implementation Method 1
forming a first resist layer in a region corresponding to the base on a surface of the first semiconductor layer
Implementation Method 2
forming a depression in the first semiconductor layer by etching the first semiconductor layer up to an intermediate portion in a thickness direction
Implementation Method 3
forming a second resist layer in a region corresponding to the rib portion on a bottom surface of the depression, a side surface of the depression, and the surface of the first semiconductor layer
Data Source
AI summary
An optical device includes a support portion, a movable portion; and a pair of torsion bars. An optical function portion is provided on one surface of the movable portion and a rib portion is provided on the other surface of the movable portion. The rib portion includes eight extending portions of first to eighth extending portions. When setting directions in which the first to eighth extending portions extend as first to eighth extending directions respectively, and setting an angle between the first and second extending directions as a first angle, an angle between the third and fourth extending directions as a second angle, an angle between the fifth and sixth extending directions as a third angle, and an angle between the seventh and eighth extending directions as a fourth angle, each of the first and second angle is larger than each of the third and fourth angle.