Tapered Through Electrode in Solid-State Image Sensors
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Solution Overview
Problem
Existing solid-state image sensors face challenges in maintaining a low resistance value for through electrodes, which affects their performance due to voids formed during the deposition process, especially as the electrodes are miniaturized and aspect ratios increase.
Innovation Solution
The design incorporates a through electrode with a conductor whose cross-sectional area gradually increases toward the photoelectric converter, allowing for improved filling characteristics and reducing void formation, thereby maintaining a low resistance value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the through electrode is miniaturized and the aspect ratio is increased, then the integration density is improved, but the resistance value increases due to void formation during deposition
Solution Approach 1:
The conductor cross-section is designed with non-uniform distribution, being larger at the photoelectric converter side and smaller at the semiconductor substrate side. This local variation in cross-sectional area compensates for the increased path length in miniaturized through electrodes, maintaining low resistance while achieving high integration density
Solution Approach 2:
The invention changes the geometric parameter of the conductor from a uniform cross-section to a tapered cross-section where the area gradually increases toward the photoelectric converter. This parameter modification reduces void formation during deposition and lowers overall resistance, resolving the contradiction between miniaturization and electrical performance
2Ease of manufacture
If a conventional through electrode with uniform cross-section is used, then the manufacturing process is simple, but voids form during deposition leading to increased resistance
Solution Approach 1:
The conductor is designed with locally varying cross-sectional area, being larger at the photoelectric converter side where void formation is more problematic during deposition. This local quality improvement enhances filling characteristics without significantly complicating the overall manufacturing process
Solution Approach 2:
The conductor geometry is pre-designed with a tapered profile before deposition begins, creating a structure that naturally prevents void formation during the filling process. This preliminary geometric configuration ensures better deposition uniformity and reduces the need for complex post-processing
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 effectively keeps the resistance value of the through electrode low, enhancing the performance and sensitivity of the solid-state image sensor by preventing voids and reducing parasitic capacitance.
Implementation Method 1
a photoelectric converter disposed above the semiconductor substrate and configured to convert light to charge
Implementation Method 2
filling the through hole with a metal film
Data Source
AI summary
A solid-state image sensor is provided that includes a semiconductor substrate, a charge accumulator disposed in the semiconductor substrate and configured to accumulate charge, a photoelectric converter provided above the semiconductor substrate and configured to convert light to charge, and a through electrode passing through the semiconductor substrate and electrically connecting the charge accumulator with the photoelectric converter. At an end portion on the photoelectric converter side of the through electrode, a cross-sectional area of a conductor positioned at the center of the through electrode in a cut section orthogonal to a through direction of the through electrode gradually increases toward the photoelectric converter along the through direction.