Dual-Chip Image Sensor Pad Structure for Simpler Interconnection
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Solution Overview
Problem
Existing image sensor manufacturing processes are complex and require intricate interconnection structures, which can lead to increased costs and manufacturing difficulties.
Innovation Solution
The proposed image sensor design simplifies manufacturing by using a dual-chip structure where a first chip with a pixel region and pad region is bonded to a second chip with driving circuits. This design includes a recess region that exposes conductive pads, reducing material residue and simplifying interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional single-chip interconnection structure is used, then the electrical connection is established, but the manufacturing process becomes complex and material residue remains on the conductive pads
Solution Approach 1:
The image sensor is divided into two separate chips: a first chip containing the pixel array and a second chip containing the driving circuits and interconnection structures. This segmentation allows the complex interconnection structure to be confined to the second chip, simplifying the manufacturing process for the first chip and eliminating material residue issues on exposed pads.
Solution Approach 2:
The complex interconnection structure is extracted from the first chip and relocated to the second chip. The second chip includes conductive pads and interconnection lines that are not exposed on the first chip surface, thereby removing the source of material residue while maintaining electrical connectivity through controlled interfaces.
2Productivity
If conductive pads are exposed on the first chip surface, then interconnection is enabled, but unwanted material residue accumulates on the pads
Solution Approach 1:
The conductive pads are extracted from the first chip surface and relocated to the second chip. The second chip includes the conductive pads and interconnection structures in an enclosed configuration, preventing material residue from accumulating on exposed pad surfaces while maintaining manufacturing efficiency.
3Reliability
If intricate interconnection structures are used, then electrical connectivity is achieved, but manufacturing costs and difficulties increase
Solution Approach 1:
The system is segmented into two chips with distinct functions: the first chip handles light sensing with simplified structures, while the second chip contains the intricate interconnection structures and driving circuits. This segmentation maintains reliable electrical connectivity while simplifying the overall manufacturing process by confining complexity to a separate component.
Solution Approach 2:
The second chip acts as an intermediary that houses the complex interconnection structures and driving circuits, mediating between the simple pixel array on the first chip and the external connections. This intermediary approach maintains electrical connectivity reliability while isolating manufacturing complexity to a dedicated component.
Data Source
AI summary
An image sensor includes a first chip that includes a pixel region and a pad region, and a second chip that is in contact with one surface of the first chip and includes circuits that drive the first chip. The first chip includes a first substrate, an interlayer insulating layer disposed between the first substrate and the second chip, first interconnection lines disposed in the interlayer insulating layer, a conductive pad disposed in the pad region between the second chip and the first interconnection lines, and a recess region formed in the pad region that penetrates the first substrate and the interlayer insulating layer and exposes the conductive pad.