Image Sensor Boundary Region Dummy Patterns for Thermal Uniformity
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Solution Overview
Problem
CMOS image sensors experience degradation in image-sensing element quality due to temperature irregularities caused by differing mean pitches of circuit patterns in the image-sensing and logic circuit regions, leading to heat transfer and thermal diffusion issues during optical annealing.
Innovation Solution
Incorporating dummy element isolation portions or dummy gate patterns in the boundary region between the image-sensing and logic circuit regions, with pitches matching those of the image-sensing element region, to equalize light absorption rates and prevent temperature irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the logic circuit region and image-sensing element region are integrated on the same chip with different mean pitches, then compact structure is achieved, but temperature irregularities occur during optical annealing causing quality degradation
Solution Approach 1:
The patent applies local quality by introducing a boundary region with specific structural characteristics between the logic circuit region and image-sensing element region. This boundary region has different properties (dummy gate patterns or dummy circuit patterns with specific pitches) to locally adjust heat distribution, ensuring that the image-sensing element region maintains uniform temperature while the logic circuit region can have higher temperature, thus resolving the temperature irregularity issue without compromising the compact integrated structure
Solution Approach 2:
The boundary region acts as an intermediary between the logic circuit region and image-sensing element region. By placing dummy gate patterns or dummy circuit patterns in this boundary region with specific pitch characteristics, it mediates the thermal interaction between the two regions, preventing excessive heat transfer to the image-sensing element region while maintaining the integrated compact structure
2Use of energy by moving object
If the pitch of gate conductors in the logic circuit region is smaller than the incident wavelength, then light absorption rate increases, but temperature becomes higher than the image-sensing element region causing heat transfer
Solution Approach 1:
The patent segments the chip into three distinct regions: logic circuit region, boundary region, and image-sensing element region. The boundary region is further segmented into first and second portions with different dummy patterns. This segmentation allows each region to have optimized pitch characteristics - the logic circuit region can maintain small pitch for high light absorption, while the boundary region controls heat transfer to protect the image-sensing element region
3Loss of energy
If heat transfers from the logic circuit region to the image-sensing element region, then thermal diffusion occurs in the peripheral region, but temperature irregularities cause characteristic variation and quality degradation
Solution Approach 1:
The patent applies preliminary anti-action by pre-configuring the boundary region with dummy gate patterns or dummy circuit patterns before the optical annealing process. These dummy structures are designed to absorb or redirect heat flow, creating a thermal buffer that prevents excessive heat transfer from the logic circuit region to the image-sensing element region, thereby preventing temperature irregularities and characteristic variations before they occur
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 approach maintains uniform temperature in the image-sensing element region, reducing characteristic variations and enhancing product quality without requiring additional manufacturing processes.
Implementation Method 1
dummy element isolation portions or dummy gate patterns in the boundary region between the image-sensing and logic circuit regions, with pitches matching those of the image-sensing element region, to equalize light absorption rates
Implementation Method 2
heat transfers from the logic circuit region to the image-sensing element region due to thermal diffusion in a portion of the image-sensing element region that is close to the logic circuit region
Data Source
AI summary
According to one embodiment, an image sensor includes an image-sensing element region formed by arranging a plurality of image-sensing elements on a semiconductor substrate and element isolation portions formed to isolate the image-sensing elements, and a logic circuit region formed in a region different from the image-sensing element region on the substrate and including a plurality of gate patterns. Further, dummy element isolation portions are arranged with a constant pitch in the boundary region between the image-sensing element region and the logic circuit region.