Semiconductor Wafer Optical Filter with Si Interlayer for Warpage Reduction
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Solution Overview
Problem
Existing semiconductor devices, particularly those incorporating infrared filters, face significant warpage issues due to the high stress applied by thicker infrared filters, which hinder the miniaturization of semiconductor wafers and devices.
Innovation Solution
The semiconductor wafer and device designs incorporate a wafer substrate with specific thickness relationships and an interlayer of Si between the optical filter and the substrate, ensuring the optical filter thickness is 10% or less of the substrate thickness and the interlayer is 50-300 μm, thereby reducing warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an infrared filter is used to emit or receive infrared light, then wavelength selectivity is improved, but warpage occurs due to the thickness and stress of the filter
Solution Approach 1:
An interlayer is introduced between the infrared filter and the wafer substrate to act as a stress buffer. This intermediary layer absorbs the stress generated by the thick infrared filter, preventing warpage while allowing the filter to maintain its wavelength selectivity function.
Solution Approach 2:
The thickness of the infrared filter is controlled to be 10% or less of the wafer substrate thickness, and the interlayer thickness is optimized to 50-300 μm. By changing these dimensional parameters, the stress distribution is improved, reducing warpage while preserving the filter's optical performance.
2Volume of moving object
If the size of the semiconductor device is reduced to achieve miniaturization, then device size is improved, but the influence of warpage becomes more significant
Solution Approach 1:
The interlayer serves as a stress buffer that becomes increasingly important as device size is reduced. In smaller devices, the same amount of stress produces greater warpage influence, so the interlayer's stress-absorbing function is critical for maintaining planarity in miniaturized devices.
Solution Approach 2:
By controlling the interlayer thickness to be 50-300 μm and the filter thickness to be 10% or less of substrate thickness, the design maintains adequate stress buffering capacity even as the overall device size is reduced, preventing warpage from becoming dominant in miniaturized configurations.
3Measurement precision
If the thickness of the infrared filter is increased to improve filtering performance, then wavelength selectivity is improved, but stress on the wafer substrate increases causing warpage
Solution Approach 1:
The interlayer acts as a stress buffer between the thick infrared filter and the wafer substrate. It absorbs the stress generated by the filter's thickness, allowing the filter to be sufficiently thick for good wavelength selectivity without transmitting excessive stress to the substrate that would cause warpage.
Solution Approach 2:
The thickness ratio between filter and substrate is controlled to be 10% or less, and the interlayer thickness is optimized to 50-300 μm. These parameter changes create an optimal stress distribution that allows thick filters for good performance while preventing substrate warpage.
4Volume of moving object
If the wafer substrate thickness is reduced to enable miniaturization, then device size is improved, but the structural stability and stress resistance decrease
Solution Approach 1:
The interlayer serves as a structural reinforcement that compensates for the reduced thickness of the wafer substrate. By providing additional mechanical support and stress distribution, it enables the use of thinner substrates for miniaturization while maintaining adequate structural stability and stress resistance.
Data Source
AI summary
Provided are a semiconductor wafer, a semiconductor device, and a gas concentration measuring device having a size reduced by reducing warpage to be even smaller than the sizes that can be achieved by conventional techniques. The semiconductor wafer includes: a wafer substrate; a semiconductor stacked portion formed on a first surface of the wafer substrate, the semiconductor stacked portion being capable of one of emitting and receiving infrared light; and an optical filter formed on a second surface of the wafer substrate that is opposite to the first surface. An interlayer made of Si with a thickness of 50 μm or more and 300 μm or less is provided between the optical filter and the wafer substrate, and a thickness Topt of the optical filter is 10% or less of a thickness of the wafer substrate.