Image Sensor Device Isolation Voltage Application
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Solution Overview
Problem
Conventional image sensors with device isolation structures suffer from dark current issues leading to white spot and blooming phenomena, which affect image quality due to crosstalk and blooming between image pixels.
Innovation Solution
An image sensor design that includes a semiconductor substrate with a device isolation structure capable of applying a voltage, featuring a deep trench isolation structure with conductive patterns and insulating layers to manage dark current, and a method for manufacturing this sensor to reduce dark current and improve pixel isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional device isolation structure (STI or DTI) is used to isolate image pixels, then pixel isolation is improved, but dark current is generated on the surface of the device isolation structure causing white spot and blooming phenomena
Solution Approach 1:
A voltage connection structure is introduced as an intermediary between the device isolation structure and the voltage applying device. This intermediary enables voltage application to the device isolation structure surface, allowing dark current suppression while maintaining the isolation function. The voltage connection structure includes a voltage connection contact plug and voltage connection insulating area, serving as a mediator to deliver control voltage to the isolation structure.
Solution Approach 2:
The electrical parameter (voltage) of the device isolation structure surface is changed by applying a negative voltage through the voltage applying device. This parameter change suppresses the generation of dark current on the surface while maintaining the isolation function. The voltage application modifies the electrical state of the isolation structure to eliminate the harmful dark current effect.
2Object-generated harmful factors
If a deep trench isolation structure is implemented to reduce dark current, then dark current suppression is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The device isolation structure serves multiple functions: it provides physical isolation between pixels, acts as a platform for voltage application to suppress dark current, and maintains structural integrity. By making the isolation structure multi-functional (isolation + voltage application target), the need for separate dark current suppression structures is eliminated, reducing overall device complexity.
Solution Approach 2:
The voltage connection structure is merged with the device isolation structure, where the voltage connection contact plug is formed in conjunction with the isolation trench. The voltage connection insulating area is integrated into the isolation structure fabrication process. This merging reduces the number of separate manufacturing steps and structures needed.
3Object-generated harmful factors
If voltage application structures are added to the device isolation structure, then dark current suppression is improved, but manufacturing precision requirements increase
Solution Approach 1:
The voltage connection insulating area is formed preliminarily during the device isolation structure fabrication process, before the voltage applying device is fully integrated. The insulating area is created as part of the trench isolation formation, establishing the voltage connection pathway early in the manufacturing sequence. This preliminary action simplifies subsequent alignment steps.
Solution Approach 2:
The voltage connection structure is segmented into distinct functional components: the voltage connection contact plug (for electrical connection), the voltage connection insulating area (for isolation and positioning), and the voltage applying device (for voltage delivery). This segmentation allows each component to be optimized and fabricated independently with appropriate precision requirements, rather than requiring high precision for the entire structure as a single unit.
Data Source
AI summary
Image sensor and method of manufacturing the same are provided. The image sensor includes a semiconductor substrate including a pixel area, a voltage connection area, and a pad area, a plurality of photoelectric conversion devices in the pixel area, an anti-reflective layer on a back side of the semiconductor substrate and on the plurality of photoelectric conversion devices, a device isolation structure between the plurality of photoelectric conversion devices, at least one voltage connection structure in the voltage connection area, and electrically connected to the device isolation structure, at least one voltage applying device electrically connected to the at least one voltage connection structure, an internal circuit including at least one conductive inner wire and at least one conductive inner via in an insulating layer, and a through via structure in the pad area.