Image Sensor Deep Trench Isolation and Surface Texture
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Solution Overview
Problem
Existing image sensors face challenges in improving photodiode efficiency and reducing interference between adjacent devices, which affects the quality of acquired images due to environmental and light-related factors.
Innovation Solution
The implementation of deep trench isolation walls in the substrate to isolate photodiodes and storage devices, along with a shielding structure and surface texture pattern layer, enhances light reception and reduces interference, thereby improving photo-sensing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep trench isolation walls are implemented to isolate photodiodes and storage devices, then interference between adjacent devices is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The isolation structure is segmented into two distinct parts: deep trench isolation walls that extend vertically to separate photodiodes and storage devices, and surface texture pattern layers that cover the top surface. This segmentation allows each component to address specific isolation needs, achieving comprehensive interference reduction while maintaining manufacturing feasibility.
Solution Approach 2:
The isolation approach transitions from traditional two-dimensional planar isolation to three-dimensional isolation by implementing deep trench walls that extend vertically through the substrate. This dimensional change provides superior isolation effectiveness by blocking interference paths in the vertical dimension, while the surface texture layer maintains planar coverage.
2Use of energy by moving object
If surface texture pattern layer is added to increase light paths through photodiode, then light receiving capacity is enhanced, but manufacturing steps and process complexity increase
Solution Approach 1:
The surface texture pattern layer incorporates curved or non-planar surface features that create multiple light paths through the photodiode. These curved surface structures increase the optical path length and improve light absorption efficiency without requiring complex internal photodiode modifications.
Solution Approach 2:
The surface texture pattern layer is formed during the manufacturing process before final device assembly, preliminarily preparing the optical interface to maximize light reception. This preliminary structuring of the surface ensures optimal light coupling and multiple path transmission is built-in from the start.
3Object-affected harmful factors
If shielding structure is disposed on second surface of substrate to shield storage devices, then environmental interference is reduced, but additional manufacturing steps are required
Solution Approach 1:
The shielding function is extracted and applied selectively only to the storage devices on the second surface of the substrate, rather than shielding the entire device. This targeted approach reduces environmental interference for sensitive components while minimizing the overall complexity and material requirements of the shielding structure.
Solution Approach 2:
The shielding structure implements local quality by providing protection only where needed - specifically over the storage devices on the second surface. This localized shielding approach addresses environmental interference for critical components without adding unnecessary complexity to the entire device structure.
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 configuration increases the number of light paths through the photodiode, enhancing light receiving capacity and reducing environmental interference, leading to improved image sensor performance.
Implementation Method 1
a photoelectric conversion unit that converts received light into an electric charge
Data Source
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AI summary
An image sensor that includes a substrate (10) is provided. A photodiode (16) is formed in the substrate (10) and in a pixel region. Storage devices (18a,18b) are formed in the substrate (10) and adjacent to the photodiode (16). Deep trench isolation walls (12) penetrate the substrate (10) to isolate the photodiode (16) from the storage devices (18a,18b). A circuit layer (26) is disposed on a first surface (10a) of the substrate (10) and connected to the photodiode (16) and the storage devices (18a,18b). A shielding structure (28) is disposed on a second surface (10b) of the substrate (10) to shield of the storage devices (18a,18b). A material layer (30) is disposed above the second surface (10b) of the substrate (10). A lens (32) is disposed on the material layer (30) and configured to receive incident light and transmit the incident light to the photodiode (16).