Photodiode Doping Structure for Short-Wavelength Response
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Solution Overview
Problem
Current photodiodes face challenges in enhancing short wavelength response and signal-to-noise ratio at high temperatures, with shallow diffusion junctions and fusion bonding leading to reduced breakdown voltage and surface recombination issues.
Innovation Solution
A photodiode design featuring a substrate with N-type and P-type doped regions, a barrier ring region, and an oxide layer, along with a method involving doping and dielectric layer formation to create a deep and shallow doped region structure, which improves short wavelength response and stability at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shallow diffusion junction is created to improve short wavelength response, then the short wavelength response is improved, but the breakdown voltage is reduced
Solution Approach 1:
The patent applies local quality by creating different doped regions with specific characteristics at different locations. The shallow doped region (5 nm-20 nm depth) is created specifically in the photosensitive region to improve short wavelength response, while the deep doped region (50 nm-200 nm depth) is created in the barrier ring region to maintain high breakdown voltage. This localized differentiation allows each region to optimize its function without compromising the other.
Solution Approach 2:
The P-type doped region is segmented into two distinct parts: a shallow doped region and a deep doped region. This segmentation allows the patent to independently optimize the properties of each region - the shallow region for short wavelength detection and the deep region for voltage breakdown prevention - thereby resolving the contradiction between improving short wavelength response and maintaining high breakdown voltage.
2Measurement precision
If fusion bonding is used to create shallow junction, then short wavelength response is improved, but surface recombination increases
Solution Approach 1:
The patent applies local quality by creating a shallow doped region specifically in the photosensitive region where light detection is needed, while maintaining a deeper doped region in the barrier ring region. This localized approach improves short wavelength response where needed without creating excessive surface recombination in the barrier region, as the deeper doping there provides better surface passivation.
3Measurement precision
If shallow doped region is created to improve short wavelength response, then detection accuracy is improved, but leakage current increases
Solution Approach 1:
The P-type doped region is segmented into shallow and deep doped regions. The shallow doped region (5 nm-20 nm) in the photosensitive area improves detection accuracy for short wavelengths, while the deep doped region (50 nm-200 nm) in the barrier ring region acts as a barrier to leakage current, thereby resolving the contradiction between improved detection and reduced leakage.
Solution Approach 2:
The deep doped region in the barrier ring region serves as an intermediary structure between the shallow doped photosensitive region and the substrate. It mediates by providing a transition zone that maintains the benefits of shallow doping for detection while preventing the harmful effects of leakage current through deeper doping in the barrier region.
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 design achieves a short wavelength response greater than 90% and reduces surface recombination, maintaining high efficiency and signal-to-noise ratio, thereby enhancing optoelectronic performance.
Implementation Method 1
a photodiode is mainly used to receive light signals and convert the light signal into a current or voltage signal
Implementation Method 2
The device structure includes an N-type doped region, a non-doped intrinsic layer, and a P-type doped region
Implementation Method 3
improving the short wavelength response... achieves a short wavelength response greater than 90%
Implementation Method 4
doping a first portion of the substrate to form a deep doped region and a shallow doped region
Implementation Method 5
surface recombination may also restrict an improvement in the short wavelength response... reducing surface recombination
Data Source
AI summary
A photodiode includes a substrate, a device structure, a barrier ring region, a photosensitive region, an oxide ring, and an oxide layer. The substrate has a first surface and a second surface opposite to the first surface. The device structure includes an N-type doped region, a non-doped intrinsic layer, and a P-type doped region. The barrier ring region is disposed in the substrate at a periphery of an upper portion of the substrate and is spaced apart from the P-type doped region. The photosensitive region is located above the P-type doped region. The oxide ring is disposed on the substrate and surrounds the photosensitive region. The oxide layer is disposed between the oxide ring and the second surface. The P-type doped region includes a deep doped region and a shallow doped region that are adjacent to each other. A method for manufacturing the photodiode is also provided.