Image Sensor Ground Contact Layout for Smaller Pixel Circuits
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Solution Overview
Problem
The increasing integration level of image sensors leads to smaller pixel and component sizes, making the process of forming pixel circuits more difficult and prone to defects, particularly due to lifting defects in mask patterning processes.
Innovation Solution
The image sensor design includes a semiconductor substrate with a p-well region under the element isolation layer, where the ground contact penetrates both the element isolation and interlayer insulating layers, allowing for reduced mask pattern complexity and preventing lifting defects, thereby enabling compact pixel miniaturization and improved process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the integration level of the image sensor is increased to reduce pixel size, then the pixel area decreases, but the difficulty of forming the pixel circuit increases and lifting defects occur in mask patterning processes
Solution Approach 1:
The ground contact is configured to extend vertically through the interlayer insulating layer and element isolation layer to contact the p-well region, utilizing the vertical dimension to reduce horizontal mask pattern requirements and prevent lifting defects during patterning processes
2Reliability
If the ground contact penetrates the element isolation layer and interlayer insulating layer to contact the p-well region, then lifting defects are prevented, but the manufacturing process complexity increases
Solution Approach 1:
The ground contact structure is merged with the existing element isolation layer and interlayer insulating layer formation processes, allowing the ground contact to be formed simultaneously with other structural layers, thereby reducing overall manufacturing steps despite the additional penetration requirement
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 design prevents lifting defects in the mask patterning process, reduces the area occupied by the ground region, and allows for increased pixel miniaturization and integration, enhancing the overall performance and reliability of the image sensor.
Implementation Method 1
each of the plurality of pixels includes a photodiode region that receives incident light and converts the received incident light to an electrical signal
Data Source
AI summary
An image sensor includes a semiconductor substrate having a first surface and a second surface. The first surface includes an element isolation trench. An element isolation layer is arranged inside the element isolation trench. The element isolation layer defines an active region. A gate electrode is arranged on the first surface of the semiconductor substrate. An interlayer insulating layer is arranged on the first surface of the semiconductor substrate and covers the gate electrode. A ground contact is configured to penetrate the element isolation layer and the interlayer insulating layer and contacts the semiconductor substrate. A color filter is arranged on the second surface of the semiconductor substrate.