Light Sensor Pixel Electrode Layout for Thicker Photoconversion Films
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Solution Overview
Problem
Existing light sensors face challenges such as increased risk of delamination and cracking when attempting to enhance the thickness of the photosensitive film for improved quantum efficiency, leading to higher production costs and reduced sensor performance.
Innovation Solution
A method for manufacturing a pixel that involves depositing an insulating layer on an interconnect structure, etching an opening to a conductive element, depositing an electrode layer in contact with the conductive element, defining the electrode by etching, and then depositing a photosensitive film that converts photons into electron-hole pairs, with the film being thicker locally above the electrode to enhance quantum efficiency while maintaining a planar upper face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the photosensitive film is increased to improve quantum efficiency, then the quantum efficiency is improved, but the risk of delamination and cracking increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness distribution of the photosensitive film. The film is thicker in the central region (above the conductive element) and thinner at the edges, allowing the central area to have high quantum efficiency while the thinner edges maintain structural integrity and reduce delamination risk. This is achieved through the specific deposition process that forms a dome-shaped or lens-shaped film profile.
Solution Approach 2:
The patent employs preliminary action by depositing the insulating layer and forming the opening to the conductive element before depositing the photosensitive film. This preparatory structure provides a controlled substrate that guides the film deposition process, ensuring the film forms the desired thickness profile from the beginning, with the opening acting as a template for the thicker central region.
2Reliability
If the thickness of the photosensitive film is increased to improve quantum efficiency, then the quantum efficiency is improved, but the production cost increases
Solution Approach 1:
The patent reduces production cost through local quality by concentrating the photosensitive material only where it is most needed (in the central region above the conductive element). This eliminates the waste of material in edge regions where it would not contribute effectively to quantum efficiency, thereby reducing overall material consumption and production cost while maintaining high efficiency in the active area.
Solution Approach 2:
The patent applies parameter changes by optimizing the thickness distribution of the photosensitive film rather than uniformly increasing thickness. By changing the thickness parameter from a constant value to a spatially varying profile (thicker in center, thinner at edges), the patent achieves high quantum efficiency with reduced total material usage, thereby lowering production costs.
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 achieves an increase in quantum efficiency of up to 13% compared to traditional pixel designs, while minimizing the risk of delamination and cracking, thus improving the overall performance and cost-effectiveness of the light sensor.
Implementation Method 1
The film is configured to implement, at the operating wavelength of the sensor, the conversion of incident photons into electron-hole pairs
Data Source
AI summary
The present disclosure relates to a method for manufacturing a pixel by: depositing an insulating layer on an exposed face of an interconnect structure of an integrated circuit, the interconnect structure having a conductive element flush with said exposed face; etching an opening passing through the insulating layer to the conductive element; depositing an electrode layer on and in contact with the conductive element and the insulating layer; defining an electrode by removing, by etching, part of the electrode layer resting on the insulating layer; and depositing a film configured to convert photons into electron-hole pairs when a ray at an operating wavelength of the pixel reaches the pixel.