Buried Gate Light Shielding for Image Sensor Stray Light
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Solution Overview
Problem
Current image sensors, such as global shutter image sensors, face interference from stray light due to the lack of effective shielding mechanisms, which affects signal integrity in storage nodes.
Innovation Solution
The implementation of a buried gate structure with a first light shielding layer, electrically connected to the buried gate, positioned above the storage node to block stray light interference, along with additional light shielding layers and dielectric layers to enhance shielding efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light shielding layer is added above the storage node, then stray light interference is reduced, but device complexity increases
Solution Approach 1:
The light shielding layer is merged with the gate structure to form an integrated component. The gate structure serves dual functions: controlling the light sensing device and shielding the storage node from stray light. This integration reduces the number of separate components and simplifies the overall device architecture while maintaining effective stray light protection.
Solution Approach 2:
The gate structure is designed to perform multiple functions simultaneously: it acts as both the control gate for the light sensing device and the light shielding layer for the storage node. This multi-functionality eliminates the need for dedicated shielding structures, thereby reducing device complexity while effectively blocking stray light.
2Object-affected harmful factors
If multiple light shielding layers are added, then shielding efficacy is improved, but manufacturing complexity increases
Solution Approach 1:
The light shielding function is segmented into multiple layers positioned at different locations: a first light shielding layer above the storage node and a second light shielding layer above the first light shielding layer. Each layer provides incremental shielding protection, and their combined effect significantly reduces stray light interference while maintaining a systematic and manageable manufacturing process.
Solution Approach 2:
The light shielding structure is extended into the vertical dimension with multiple layers stacked above each other. This vertical arrangement provides enhanced shielding efficacy by blocking stray light from multiple angles and depths, while the layered structure follows standard semiconductor manufacturing processes, keeping fabrication complexity manageable.
3Object-affected harmful factors
If the light shielding layer extends into the buried gate, then shielding coverage is improved, but electrical connection complexity increases
Solution Approach 1:
The light shielding layer is merged with the buried gate structure, with the shielding layer extending into and integrating with the gate. This integration ensures that the light shielding function and the electrical conduction function are combined in a single structure, eliminating the need for separate connection elements and simplifying the electrical connection architecture.
Solution Approach 2:
The buried gate structure serves as an intermediary that simultaneously provides electrical conduction and light shielding functions. By extending the light shielding layer into the buried gate, the gate structure mediates between the electrical signal transmission requirement and the stray light blocking requirement, achieving both functions through a single integrated component.
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
Effectively prevents stray light from illuminating the storage node, thereby reducing interference and improving signal quality in image sensors.
Implementation Method 1
The first light shielding layer is disposed on the buried gate and located above the storage node. The first light shielding layer is electrically connected to the buried gate. Effectively prevents stray light from illuminating the storage node
Data Source
AI summary
A manufacturing method of an image sensor including the following steps is provided. A substrate is provided. A light sensing device is formed in the substrate. A storage node is formed in the substrate. The storage node and the light sensing device are separated from each other. A buried gate structure is formed in the substrate. The buried gate structure includes a buried gate and a first dielectric layer. The buried gate is disposed in the substrate and covers at least a portion of the storage node. The first dielectric layer is disposed between the buried gate and the substrate. A first light shielding layer is formed on the buried gate. The first light shielding layer is located above the storage node and electrically connected to the buried gate.