Trench Capacitor Electrode Protection in CMOS Image Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional capacitors in CMOS image sensor circuits suffer from poor electrical performance due to etching loss of conductive layers above the semiconductor substrate, leading to degradation in capacitor performance.
Innovation Solution
A method for fabricating a capacitor involving the formation of trench structures on a base substrate with a dielectric layer and electrode layer, where the electrode layer is positioned below the surface, and an isolation layer is used to protect the dielectric and electrode layers from subsequent etching processes, ensuring improved electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electrode layer is formed above the semiconductor substrate surface, then the capacitor can be integrated into the CMOS image sensor circuit, but the conductive layer suffers from etching loss during subsequent fabrication processes
Solution Approach 1:
The patent inverts the conventional capacitor structure by positioning the electrode layer below the semiconductor substrate surface instead of above it. This inversion protects the conductive layer from etching loss during subsequent fabrication processes while maintaining electrical functionality through vertical connections via contact holes.
Solution Approach 2:
The patent transitions the electrode layer from a horizontal positioning (above substrate surface) to a vertical positioning (below substrate surface). This dimensional change moves the conductive layer into a protected region that is shielded from surface-level etching processes, thereby preserving manufacturing precision.
2Device complexity
If conventional capacitor structures are used, then the fabrication process is simple, but the electrical performance degrades due to etching loss
Solution Approach 1:
By inverting the capacitor structure to position electrodes below the substrate surface, the patent protects the conductive layer from etching damage. This structural inversion maintains fabrication simplicity while significantly improving electrical performance reliability through enhanced process robustness.
3Manufacturing precision
If the electrode layer is positioned below the surface, then etching loss is prevented, but additional fabrication steps are required
Solution Approach 1:
The patent performs preliminary actions by forming the electrode layer and capacitor structure below the substrate surface before subsequent CMOS circuit fabrication steps. This advance positioning protects the conductive layer from future etching processes, maintaining manufacturing precision despite additional initial fabrication steps.
Data Source
AI summary
A capacitor, an image sensor circuit and fabricating methods are provided. The method includes providing a base substrate including a trench region and a body region adjacent to the trench region. The method also includes forming a first trench structure and a second trench structure on the first trench structure, in the base substrate in the trench region. In addition, the method includes forming a dielectric layer on a sidewall surface and a bottom surface of the first trench structure and an electrode layer on the dielectric layer in the first trench structure. Further, the method includes forming an isolation layer filling the second trench structure.