Stacked Photoelectric Conversion Layout for Lower Coupling Capacitance
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Solution Overview
Problem
Existing photoelectric conversion devices face challenges in further suppressing coupling capacitance, which affects image quality.
Innovation Solution
A photoelectric conversion device is designed with a specific stacking configuration, including a first semiconductor layer with floating diffusions, a second semiconductor layer, and wiring structures connected via metal pads. The configuration includes a conductive pattern extending from a metal pad not connected to the floating diffusions, which helps suppress coupling capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal pads are arranged closely to connect floating diffusions to transistors, then connection efficiency is improved, but coupling capacitance between adjacent metal pads increases
Solution Approach 1:
A third metal pad is introduced as an intermediary element between the first and second metal pads. This intermediate pad acts as a shielding structure that reduces the direct capacitive coupling between the signal-carrying pads, thereby lowering coupling capacitance while maintaining efficient electrical connections through the wiring structure.
Solution Approach 2:
The harmful capacitive coupling effect is extracted and isolated by introducing a dedicated third metal pad that serves specifically as a shielding element. This separates the signal transmission function (performed by first and second metal pads) from the capacitance reduction function (performed by the third metal pad), allowing optimization of both aspects.
2Adaptability or versatility
If wiring patterns are routed through the second semiconductor layer to connect metal pads and transistors, then layout flexibility is improved, but manufacturing complexity increases
Solution Approach 1:
The wiring structure is segmented into multiple distinct layers: metal pads in the first wiring structure, additional metal pads in the second wiring structure, and wiring patterns routed through the second semiconductor layer. This segmentation allows each component to be optimized independently - metal pads for electrical connection and wiring patterns for signal routing - thereby achieving layout flexibility while managing manufacturing complexity through clear structural division.
Data Source
AI summary
A device in which a first semiconductor including first and second floating diffusions, a first structure, a second structure and a second semiconductor are stacked in this order is provided. The first and second structures are bonded with metal pads including first and second pads and third pad arranged between the first and second pads. First and second transistors are arranged on a side of the second semiconductor opposite to the first semiconductor, the first floating diffusion is connected to the first transistor via the first pad, the second floating diffusion is connected to the second transistor via the second pad, and a conductive pattern extending toward the first semiconductor from the third pad. Wiring patterns connecting the first pad and the first transistor and connecting the second pad and the second transistor are arranged to extend through the second semiconductor.