Low-k Insulating Layer Moisture Protection in Image Pickup Apparatus
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Solution Overview
Problem
CSP-type image pickup apparatuses using low-k materials for insulating layers face reliability issues due to moisture infiltration, leading to increased parasitic capacitance and potential operation failures, as these materials are inferior in humidity and water resistance.
Innovation Solution
The image pickup apparatus incorporates a rewiring layer with low-permittivity insulating layers, exposed conductors, and a guard ring to prevent moisture infiltration, along with a dual protection film structure using insulating and metal materials to enhance moisture-proofing and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If low-k materials are used for insulating layers to reduce parasitic capacitance, then manufacturing precision and device performance are improved, but reliability deteriorates due to moisture infiltration
Solution Approach 1:
The patent applies this principle by forming a moisture-proof film (such as aluminum oxide or aluminum nitride) over the low-k material insulating layers. This thin film acts as a protective barrier that prevents moisture infiltration while maintaining the electrical performance benefits of the low-k material, thus resolving the contradiction between reduced parasitic capacitance and improved moisture resistance.
Solution Approach 2:
The patent uses composite materials by combining low-k material insulating layers with moisture-proof films in a layered structure. The low-k material provides low parasitic capacitance while the moisture-proof film provides humidity resistance, creating a composite structure that achieves both electrical performance and environmental stability.
2Ease of manufacture
If rewiring layer is exposed at outer peripheral portion and through holes are formed, then ease of manufacture is improved, but reliability worsens due to increased moisture infiltration paths
Solution Approach 1:
The patent extends the moisture-proof film not only over the central region but also to the outer peripheral portions where the rewiring layer is exposed and to the bottom faces of through holes. This extension creates a continuous protective barrier that seals off moisture infiltration paths while maintaining manufacturing accessibility, thus resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The patent extracts the moisture-proofing function as a separate protective layer that is applied after the rewiring structure is formed. This allows the rewiring layer to remain accessible for manufacturing while the moisture-proof film is subsequently added to protect exposed areas, separating the manufacturing accessibility requirement from the moisture protection requirement.
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 effectively prevents moisture infiltration, maintaining high reliability and preventing property degradation even in harsh environments, such as high-temperature and humidity conditions, while allowing for downsized and high-productivity manufacturing.
Implementation Method 1
a plurality of insulating layers each including a low-permittivity insulating body having a permittivity that is lower than a permittivity of silicon oxide
Implementation Method 2
the etched area is covered by a second protection film including a metal material, via a first protection film including an insulating material
Data Source
AI summary
An image pickup apparatus includes a silicon layer, a rewiring layer including low-permittivity insulating bodies having a permittivity that is lower than a permittivity of silicon oxide, and a cover glass, and a cutout portion is provided in the silicon layer, wirings are provided on the cutout portion, the wirings do not cover at least a part of the low-permittivity insulating bodies in the rewiring layer, the low-permittivity insulating body being exposed at the cutout portion, and the cutout portion is covered by a second protection film including a metal material via a first protection film including an insulating material.