Infrared Sensor Substrate Hole Shape Control
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Solution Overview
Problem
Conventional methods for forming holes with a transverse sectional shape as a polygon in substrates using dry etching result in a blunted shape at the processing ending end, failing to achieve a predetermined polygonal shape.
Innovation Solution
A method involving a mask with penetrating holes having inwardly convex arcuate shapes is used for dry etching, allowing the transverse sectional shape of the hole's ending end to be closer to the predetermined polygon, such as a quadrilateral or triangle, by adjusting the etching process to form a substrate suitable for infrared sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If dry etching is applied using a mask with a penetrating hole having a polygonal transverse section, then a hole with a polygonal transverse section is formed in the substrate, but the transverse sectional shape at the processing ending end side becomes blunted and deviates from the predetermined polygon
Solution Approach 1:
The mask's penetrating hole is designed with a transverse sectional shape that is different from the desired final hole shape. Specifically, the mask opening is made larger or differently shaped (e.g., rectangular) so that after etching, the resulting hole achieves the target polygonal shape (e.g., triangular) at the processing ending end side. This preliminary design of the mask geometry compensates for the blunting effect that occurs during etching.
Solution Approach 2:
The invention changes the geometric parameters of the mask's penetrating hole to achieve the desired hole shape. By adjusting the shape, size, and orientation of the mask opening relative to the etching process parameters, the final hole shape at the processing ending end side can be controlled to match the predetermined polygon, counteracting the natural blunting tendency of the etching process.
2Manufacturing precision
If the mask opening is made smaller to achieve a precise polygonal shape, then shape accuracy improves, but the etching process becomes less efficient and productivity decreases
Solution Approach 1:
The mask is designed with a larger, more efficient opening shape (such as rectangular) that allows for faster etching while still producing the desired polygonal hole shape at the processing ending end. This preliminary geometric design enables the etching process to operate at higher efficiency without sacrificing the final shape accuracy, as the mask geometry is specifically tailored to compensate for etching effects.
3Ease of manufacture
If conventional dry etching is used with a standard mask, then the manufacturing process is simple, but the transverse sectional shape cannot be formed to a predetermined polygon with high accuracy
Solution Approach 1:
The mask is designed in advance with a specific geometric configuration where the transverse sectional shape of the penetrating hole is intentionally made different from the desired final hole shape. This preliminary design allows conventional dry etching processes to produce the target polygonal shape (e.g., triangular, quadrangular) at the processing ending end side, maintaining manufacturing simplicity while achieving high shape accuracy.
Solution Approach 2:
The invention introduces asymmetry or deliberate geometric mismatch between the mask opening shape and the desired final hole shape. The mask opening is designed with specific geometric characteristics (e.g., rectangular with rounded corners) that, when subjected to etching, transform into the target polygonal shape, thereby achieving both manufacturing simplicity and shape precision.
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 enables the formation of substrates with holes having a transverse sectional shape at the processing ending end that is closer to a predetermined polygon, facilitating the manufacturing of infrared sensors with improved thermal separation and structural integrity.
Implementation Method 1
dry etching using a mask having a penetrating hole with a transverse section that is a polygon is applied to the substrate
Data Source
AI summary
A resist mask 40, having penetrating holes 41, is formed on a rear surface of a silicon substrate 2. A planar shape of each penetrating hole 41 is formed to a shape with which its respective sides are curved to inwardly convex arcuate shapes with respect to a regular quadrilateral that is a target shape of a transverse section at a processing ending end side of a corresponding cavity 3. Next, dry etching is applied to the silicon substrate 2. The cavities 3 are thereby formed in the silicon substrate 2. As the etching progresses, a transverse sectional shape of each cavity 3 decreases in inward projection amounts of the respective arcuate shaped sides in the transverse sectional shape of the corresponding penetrating hole 41 of the resist mask 40. At a processing ending end side of the cavity 3, its planar shape is substantially the same shape as the regular quadrilateral that is the target shape.