Solid-State Image Sensor Sealing With Gap-Jointed Transparent Cover
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Solution Overview
Problem
The reliability of solid-state imaging apparatuses is compromised due to the increased number of joint surfaces between sealing members and solid-state image sensor chips, which can lead to reduced reliability and performance.
Innovation Solution
A solid-state imaging apparatus is designed with a transparent member directly joined to the chip via a projecting portion, maintaining a gap between the transparent member and the imaging region, thereby reducing joint surfaces and enhancing joint strength, and using a glass substrate with a coefficient of thermal expansion within 2.4 to 3.5 ppm/°C to minimize thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing member is adhered to the solid-state image sensor chip using an adhesive, then the chip can be sealed, but the number of joint surfaces increases which reduces reliability
Solution Approach 1:
The sealing member and the transparent member are merged into a single integrated component. The transparent member simultaneously performs sealing and light transmission functions, eliminating the need for separate sealing members and adhesives. This reduces the number of joint surfaces from multiple interfaces (chip-sealing member, sealing member-adhesive, adhesive-transparent member) to a single interface (chip-transparent member), thereby improving reliability.
Solution Approach 2:
The adhesive layer is extracted/removed from the structure. By directly joining the transparent member to the chip without using an adhesive, the patent eliminates the adhesive layer and its associated joint surfaces, reducing complexity and improving reliability while maintaining the sealing function.
2Strength
If the transparent member is directly joined to the chip, then joint strength increases, but thermal stress may increase due to coefficient of thermal expansion differences
Solution Approach 1:
The patent changes the material parameter of the transparent member by selecting glass with a specific coefficient of thermal expansion (2.4 to 3.5 ppm/°C) that closely matches the semiconductor substrate. This parameter matching minimizes thermal stress at the joint surface while maintaining strong direct joining, resolving the contradiction between joint strength and thermal stress.
3Reliability
If the transparent member contacts the imaging region, then sealing is achieved, but light reflection increases due to refractive index difference
Solution Approach 1:
The transparent member is segmented into two functional regions: a peripheral sealing portion that contacts the chip to provide sealing, and a central transparent portion that maintains a gap from the imaging region to prevent light reflection. This segmentation allows the sealing function and optical function to be separated spatialally, achieving both sealing and minimal light reflection.
Solution Approach 2:
Different regions of the transparent member have different local qualities: the peripheral region has contact quality for sealing, while the central region has non-contact quality for optical performance. The projecting portion creates a local gap structure that prevents contact between the transparent member and the imaging region, reducing light reflection while maintaining sealing at the periphery.
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 configuration improves the reliability and optical performance of the solid-state imaging apparatus by reducing light reflection and thermal stress, while maintaining a single joint interface and preventing contact between the chip and transparent member on the imaging region, thus enhancing the apparatus's miniaturization and resolution.
Implementation Method 1
a transparent member that is directly joined to the chip via a projecting portion of the transparent member, the projecting portion maintaining a gap between the transparent member and an imaging region of the solid-state image sensor
Implementation Method 2
a coefficient of thermal expansion of glass of the glass substrate may be within a range of 2.4 to 3.5 ppm/° C. This brings about the effect that the difference in coefficient of thermal expansion between the transparent member and the chip is reduced
Implementation Method 3
improves the joint strength by direct joining, and brings about the effect that light reflection caused by the difference in refractive index on the joint surface is suppressed
Data Source
AI summary
To improve reliability of a solid-state imaging apparatus. A solid-state imaging apparatus includes: a chip; and a transparent member. A solid-state image sensor is formed in the chip. The transparent member is directly joined to the chip via a projecting portion. The projecting portion of the transparent member is formed so as to maintain a gap between the transparent member and an imaging region of the solid-state image sensor of the chip. A protective film may be formed on a semiconductor substrate via an anti-reflection film. A color filter or an on-chip lens may be formed for each pixel in the imaging region of the solid-state image sensor of the chip.