Guard Structures for CMOS Image Sensor Through-Via Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices, particularly CMOS image sensor devices, face issues with dark current, noise, and white pixel phenomena due to through-via process charging and stress, which affect their performance and yield.
Innovation Solution
The implementation of novel guard structures comprising continuous or non-continuous rings of conductive or semiconductive material, such as metal features, P-type, and N-type regions, between the array region and through-vias or periphery regions, which reduce noise and improve electrical connections by providing shielding and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through-vias are used to connect array region and periphery region, then electrical connection is improved, but noise and dark current increase due to process charging and stress
Solution Approach 1:
A guard structure comprising conductive material is introduced as an intermediary element between the array region and periphery region. This guard structure acts as a mediator that provides an alternative path for electrical connection while isolating the sensitive array region from the harmful process charging and stress generated by through-vias, thereby reducing noise and dark current without compromising electrical connectivity.
Solution Approach 2:
The semiconductor device is segmented into distinct regions: array region, periphery region, and an intermediate guard region. This segmentation separates the sensitive photodetector array from the through-vias that cause harmful effects, allowing each region to be optimized independently while maintaining overall device functionality.
2Measurement precision
If guard structures are added to reduce noise and dark current, then signal quality is improved, but device complexity increases
Solution Approach 1:
The guard structure is implemented locally only in the regions where it is most needed - between the array region and periphery region where through-vias are present. This localized approach improves signal quality by reducing noise and dark current in critical areas without adding unnecessary complexity to the entire device structure.
Solution Approach 2:
The guard structure utilizes conductive material that can be integrated with existing semiconductor fabrication processes. By employing materials and structures that are compatible with standard manufacturing techniques, the solution enhances signal quality while minimizing the increase in device complexity.
3Manufacturing precision
If novel guard structures are implemented, then manufacturing precision is improved by reducing white pixel issues, but ease of manufacture decreases due to additional process steps
Solution Approach 1:
The guard structure is formed as part of the preliminary fabrication steps, integrating the noise-reduction feature into the base structure before subsequent processing. This preliminary integration ensures manufacturing precision by preventing white pixel issues early in the fabrication process while minimizing the impact on overall manufacturing ease.
Solution Approach 2:
The guard structure modifies key process parameters such as doping concentration and material composition in specific regions to reduce white pixel issues and improve yield. By carefully controlling these parameters during fabrication, the solution enhances manufacturing precision while keeping the additional process steps manageable.
Data Source
AI summary
Semiconductor devices, methods of manufacturing thereof, and image sensor devices are disclosed. In some embodiments, a semiconductor device includes a semiconductor chip comprising an array region, a periphery region, and a through-via disposed therein. A guard structure is disposed in the semiconductor chip between the array region and the through-via or between the through-via and a portion of the periphery region. A portion of the guard structure is disposed within a substrate of the semiconductor chip.