Stacked Quantum Photodiode Structure for Higher Light Sensitivity
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Solution Overview
Problem
Complementary metal-oxide semiconductor (CMOS) image sensor devices face challenges in maximizing the quantum length of photodiodes, leading to reduced sensitivity and energy conversion efficiency due to thin quantum material layers.
Innovation Solution
The implementation of a multi-layer photodiode structure with a stacked configuration of multiple sensing structures formed from quantum effect materials, such as germanium, increases the quantum effect length and allows for shared substrates with integrated circuitry, reducing resource consumption during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer photodiode structure is used, then the device complexity is low, but the quantum length is insufficient leading to reduced light sensitivity
Solution Approach 1:
The patent transitions from a single-layer (2D) photodiode structure to a multi-layer stacked (3D) photodiode structure. This dimensional change increases the quantum length by stacking multiple sensing structures vertically, thereby improving light sensitivity without planar expansion. The stacked configuration allows photons to interact with multiple quantum material layers, enhancing the probability of photon absorption and charge generation.
Solution Approach 2:
The patent employs composite material structures by combining multiple quantum effect material layers (such as germanium and silicon-germanium) with different optical and electrical properties. Each layer is engineered with specific bandgap characteristics to detect different wavelengths of light, creating a composite photodiode structure that achieves superior light sensitivity across multiple spectral ranges compared to single-material structures.
2Reliability
If quantum length is increased to improve light sensitivity, then light sensitivity improves, but resource consumption increases
Solution Approach 1:
By stacking photodiode layers vertically in the third dimension, the patent achieves increased quantum length and improved light sensitivity without increasing the lateral footprint of the device. This vertical integration allows multiple sensing functions to be packed into a compact volume, reducing the overall device area and associated resource consumption while maintaining enhanced light sensitivity.
3Reliability
If multiple sensing structures are stacked to increase quantum length, then light sensitivity improves, but manufacturing complexity increases
Solution Approach 1:
The patent divides the photodiode structure into multiple discrete sensing layers, each with specific quantum material compositions and thicknesses optimized for different wavelength ranges. This segmentation allows for modular manufacturing where each layer can be independently formed and characterized, facilitating systematic quality control and reducing overall manufacturing complexity despite the increased number of layers.
Solution Approach 2:
The stacked photodiode structure is designed with universal compatibility across standard semiconductor manufacturing processes. The same fabrication techniques (epitaxial growth, ion implantation, metallization) used for single-layer photodiodes are extended to multi-layer structures, allowing existing manufacturing infrastructure to produce enhanced devices without requiring entirely new process equipment or methods.
4Productivity
If a multi-layer photodiode structure is implemented, then manufacturing yield improves, but device complexity increases
Solution Approach 1:
The patent segments the multi-layer photodiode structure into distinct functional layers that can be independently fabricated and tested. This segmentation enables intermediate quality checks between layers during manufacturing, allowing defects to be detected and addressed at specific stages rather than discovering failures only after complete device assembly, thereby improving overall manufacturing yield despite the increased structural complexity.
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 approach enhances the performance, quality, and reliability of optoelectronic devices by increasing the quantum length, improving manufacturing yield, and reducing field failures, while also conserving resources.
Implementation Method 1
Complementary metal oxide semiconductor (CMOS) image sensor (CIS) devices utilize light-sensitive CMOS circuitry to convert light energy into electrical energy. As the photodiode structure is exposed to light, an electrical charge is induced in the photodiode structure (referred to as a photocurrent).
Implementation Method 2
a first sensing structure that extends into the first substrate, includes a first quantum effect material, and has sidewalls that are adjacent to first doped isolation regions that are within the first substrate
Data Source
AI summary
Some implementations described herein provide an optoelectronic device including a multi-layer photodiode structure. The multi-layer photodiode structure includes a stacked configuration of multiple sensing structures formed from quantum effect materials (e.g., a germanium material). By using the stacked configuration of multiple sensing structures, a quantum effect length is increased relative to another photodiode including a single layer photodiode structure. Furthermore, a lower sensing structure of the multi-layer sensing structure shares a substrate with integrated circuitry of the optoelectronic device. The lower sensing structure is electrically isolated from the integrated circuitry by doped isolation regions adjacent to sidewalls of the lower sensing structure.