Chip-Scale Optical Sensor Package with Thin Glass Wafer
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Solution Overview
Problem
The existing production processes of optical sensor devices face challenges with warpage and stress-related breakage due to the thickness of glass wafers, which are typically required to be at least 300 µm to prevent warpage, contributing to the overall height and bulk of the packaged device.
Innovation Solution
A chip-scale package design for optical sensor semiconductor devices that includes a semiconductor substrate with an integrated optical sensor element, a filter element arranged between the substrate and a thin glass wafer, with an intermediate layer to reduce stress and allow for a glass wafer thickness of less than 200 µm, and in some embodiments, less than 100 µm, thereby minimizing the overall package thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick glass wafer (≥300 µm) is used to prevent warpage and stress-related breakage, then the structural integrity and reliability of the device are improved, but the overall package thickness and device size increase
Solution Approach 1:
The patent segments the glass wafer into multiple thinner layers (first glass layer and second glass layer) separated by an intermediate layer. This segmentation allows each individual glass layer to be thin enough to reduce overall package thickness while collectively providing sufficient structural support to prevent warpage and breakage, resolving the contradiction between reliability and package thickness.
Solution Approach 2:
The patent introduces an intermediate layer between the first and second glass layers. This intermediary layer distributes and reduces stress across the glass structure, preventing stress concentration that would cause warpage or breakage in thinner glass wafers. The intermediate layer acts as a mediator that enables the use of thin glass layers while maintaining structural integrity, thus resolving the contradiction between reliability and package thickness.
2Length of stationary object
If a thin glass wafer (<200 µm) is used to reduce package thickness, then the device size is minimized, but the risk of warpage and stress-related breakage increases
Solution Approach 1:
The patent divides the thin glass structure into multiple segments (first glass layer and second glass layer), each thinner than 200 µm. This segmentation reduces the overall package thickness while the distributed structure prevents stress concentration, thereby maintaining reliability despite using thin glass layers.
Solution Approach 2:
The intermediate layer serves as a stress-distributing intermediary between thin glass layers. It prevents stress concentration that would normally cause warpage or breakage in thin glass, enabling the use of thin glass wafer (<200 µm) while maintaining structural integrity and preventing warpage.
3Stability of the object's composition
If a thick glass wafer is used to support the filter element, then the structural stability is improved, but the manufacturing complexity and material usage increase
Solution Approach 1:
The patent segments the glass wafer into multiple thinner layers with an intermediate layer, which simplifies the manufacturing process. Thinner glass layers are easier to handle, process, and assemble than a single thick glass wafer, reducing manufacturing complexity while maintaining structural stability through the segmented design.
Solution Approach 2:
The intermediate layer acts as a manufacturing intermediary that facilitates the assembly of thin glass layers. It provides a bonding interface that simplifies the manufacturing process compared to creating a single thick glass wafer, while the layered structure maintains structural stability.
4Length of stationary object
If the glass wafer thickness is reduced to minimize package size, then the device compactness is improved, but the stress distribution and warpage control become more difficult
Solution Approach 1:
The patent segments the glass structure into multiple thin layers, which individually have minimal warpage tendency. The segmented design allows each layer to maintain flatness while the overall structure achieves compact thickness, improving warpage control despite reduced glass wafer thickness.
Solution Approach 2:
The intermediate layer acts as a stress-distributing intermediary that prevents warpage in thin glass layers. It ensures uniform stress distribution across the thin glass structure, maintaining warpage control and structural stability even when the overall package thickness is minimized.
Data Source
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AI summary
Chip-scale package for an optical sensor semiconductor device with filter and method of producing a chip-scale package The chip-scale package comprises a semiconductor substrate (1) with a main surface (10), an optical sensor element (2) integrated in the substrate at the main surface, a filter element (3) arranged above the sensor element, and a glass wafer (4) arranged above the main surface, so that the filter element is arranged between the main surface and the glass wafer. An intermediate layer (9) is arranged between the filter element and the glass wafer, which is attached to the intermediate layer. The glass wafer has a thickness (t) in the direction perpendicular to the main surface of less than 200 µm.