Image Sensor Masking Layer and Optical Resonator Design
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Solution Overview
Problem
The existing image sensor devices face surface damage and degraded image sensing capability due to multiple etching processes during the CMOS process, which affects the light sensitivity and accuracy of the device.
Innovation Solution
An image sensor device is designed with a masking layer formed above the image sensor area, which is not completely removed, and an optical resonator is added to enhance light sensitivity, eliminating the need for additional etching steps and protecting the surface from damage. The masking layer can be made of materials like oxide, nitride, or polysilicon, and the optical resonator includes reflective and transmissible layers to filter specific frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple etching processes are used to form light passage and remove polysilicon layer, then light sensitivity is improved, but surface damage occurs and image sensing capability degrades
Solution Approach 1:
A sacrificial layer is introduced as an intermediary component between the image sensor area and the polysilicon layer. This sacrificial layer serves as a buffer that protects the image sensor area surface from direct exposure to etching processes, allowing the polysilicon layer to be removed while maintaining surface integrity. The sacrificial layer is subsequently removed through a separate etching step, achieving both surface protection and light sensitivity improvement.
2Illumination intensity
If polysilicon layer is removed to increase light sensitivity, then light sensing ability is improved, but surface damage and manufacturing complexity increase
Solution Approach 1:
The sacrificial layer is integrated into the existing CMOS fabrication process sequence, combining its formation with the standard process steps. The sacrificial layer is formed using the same deposition processes as other dielectric layers, and its removal is combined with subsequent processing steps, thereby achieving surface protection without significantly increasing manufacturing complexity.
3Object-affected harmful factors
If additional etching steps are added to protect image sensor area, then surface damage is reduced, but manufacturing complexity and time increase
Solution Approach 1:
The sacrificial layer is formed in advance, before the polysilicon layer deposition and subsequent etching processes. This preliminary action establishes the protective barrier early in the fabrication sequence, allowing subsequent steps to proceed without additional protective measures, thereby reducing overall manufacturing time while still providing surface protection.
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 solution prevents surface damage and enhances light sensitivity by maintaining the masking layer and incorporating an optical resonator, improving the image sensing capability without additional deposition or etching steps, thereby increasing the device's accuracy and efficiency.
Implementation Method 1
the optical resonator includes reflective and transmissible layers to filter specific frequencies
Data Source
AI summary
The present invention discloses an image sensor device and a method for making an image sensor device. The image sensor device includes an optical pixel and an electronic circuit. The optical pixel includes: a substrate; an image sensor area formed in the substrate; a masking layer formed above the image sensor area, wherein the masking layer is formed during a process for forming the electronic circuit; and a light passage above the masking layer for increasing light sensing ability of the image sensor area.