BSI Image Sensor Cambered Backside Surface Light Convergence
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Solution Overview
Problem
BSI image sensors face challenges in achieving ever-decreasing size, improved photo-electric conversion efficiency, and sensitivity while maintaining low noise, as existing manufacturing methods do not effectively enhance light convergence and sensitivity.
Innovation Solution
A manufacturing method for BSI image sensors involves forming cambered surfaces on the backside of the substrate corresponding to sensing elements through thermal treatment, which serve as light-convergence units, combined with micro-lenses to condense and direct incident light to the sensing elements, thereby improving photo-electric conversion efficiency and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing methods are used for BSI image sensors, then the device can be produced with standard processes, but the photo-electric conversion efficiency and sensitivity are insufficient
Solution Approach 1:
The patent applies curvature to the backside surface of the substrate by forming cambered surfaces that correspond to the positions of sensing elements. This curved surface configuration serves as a light-convergence unit that focuses incident light onto the sensing elements, thereby improving photo-electric conversion efficiency and sensitivity without requiring complex additional optical components
Solution Approach 2:
The patent changes the physical parameter of the substrate surface from flat to cambered/curved through thermal treatment processes. This parameter change in surface geometry creates light-convergence effects that enhance the optical performance of the BSI image sensor, addressing the limitation of insufficient sensitivity in conventional flat-surface designs
2Volume of moving object
If the size of BSI image sensors is decreased, then integration and portability are improved, but light convergence and sensitivity become more difficult to maintain
Solution Approach 1:
By forming cambered surfaces on the backside of the substrate, the patent creates an integrated light-convergence structure that works effectively within the compact sensor form factor. The curved surface geometry provides optical focusing capability without requiring additional space, thus maintaining sensitivity even as sensor size decreases
Solution Approach 2:
The backside surface of the substrate serves multiple functions: it acts as both the structural base of the sensor and as a light-convergence unit through its cambered configuration. This multi-functionality allows the sensor to maintain high sensitivity in a compact design by eliminating the need for separate light-focusing components
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
The method enhances the photo-electric conversion efficiency and sensitivity of BSI image sensors by forming cambered surfaces and micro-lenses on the backside of the substrate, effectively condensing and directing incident light to the sensing elements, addressing the limitations of existing technologies.
Implementation Method 1
a thermal treatment is performed to the back side of the substrate to form a plurality of cambered surfaces on the back side of the substrate
Implementation Method 2
the cambered surfaces serve as light-convergence units and thus the incident light are condensed and aimed to the sensing elements
Data Source
AI summary
A method for manufacturing a BSI image sensor includes following steps: A substrate is provided. The substrate includes a front side and a back side opposite to the front side. The substrate further includes a plurality of isolation structures and a plurality of sensing elements formed therein. Next, the isolation structures are exposed from the back side of the substrate. Subsequently, a thermal treatment is performed to the back side of the substrate to form a plurality of cambered surfaces on the back side of the substrate. The cambered surfaces are formed correspondingly to the sensing elements, respectively.