SPAD Oxide Film Stack for Breakdown Voltage Stability
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Solution Overview
Problem
The breakdown voltage in single-photon avalanche photodiodes (SPADs) changes over time due to hot carriers trapped near the cathode region, affecting the stability and performance of the photoelectric conversion apparatus.
Innovation Solution
A photoelectric conversion apparatus is designed with an avalanche diode in a semiconductor layer, featuring a specific stacking of an oxide film and a protection film, where the thickness of the oxide film is greater than a certain threshold relative to the protection film, to reduce the impact of hot carriers on the breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intense electric field is applied to the P-N junction diode to enable avalanche multiplication and photon detection, then the photoelectric conversion capability is improved, but hot carriers are generated and trapped near the cathode region, causing breakdown voltage to change over time
Solution Approach 1:
The patent introduces an oxide film as an intermediary layer between the cathode region and the hot carrier trapping region. This oxide film acts as a mediator that prevents hot carriers from being trapped near the cathode, thereby maintaining breakdown voltage stability while preserving the intense electric field necessary for avalanche multiplication and photon detection
Solution Approach 2:
The patent modifies the physical and chemical parameters of the cathode region by forming an oxide film with specific thickness and composition. This parameter change alters the hot carrier behavior and trapping characteristics, reducing the harmful effects of hot carrier accumulation on breakdown voltage stability
2Reliability
If the oxide film thickness is increased to reduce hot carrier trapping, then breakdown voltage stability is improved, but the device structure becomes more complex and manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the oxide film thickness to a specific range that balances hot carrier suppression with manufacturing feasibility. By carefully selecting and controlling the thickness parameter within an optimal range, the patent achieves breakdown voltage stability while maintaining reasonable manufacturing precision requirements
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 configuration stabilizes the breakdown voltage over time, enhancing the performance and reliability of the photoelectric conversion apparatus by minimizing the change in electric field intensity and potential changes caused by trapped hot carriers.
Implementation Method 1
hot carriers are trapped near a cathode region, which results in potential changes, and there arises an issue that the breakdown voltage changes over time
Implementation Method 2
avalanche multiplication is caused by an intense electric field applied to a P-N junction diode disposed in a semiconductor substrate, and photons are detected
Implementation Method 3
avalanche multiplication is caused by an intense electric field applied to a P-N junction diode disposed in a semiconductor substrate, and photons are detected
Data Source
AI summary
A photoelectric conversion apparatus includes an avalanche diode (APD) disposed in a semiconductor layer including a first surface and a second surface facing the first surface, and a first wiring structure in contact with the second surface, wherein a first pad configured to apply a first voltage to the photoelectric conversion apparatus is disposed in the first wiring structure, wherein an oxide film and a protection film stacked on the oxide film are disposed on the second surface of the semiconductor layer, and wherein a portion satisfying the following inequality is disposed:dsio>(εsio/εprot)×dprot/2,where a thickness of the oxide film is dsio, a thickness of the protection film is dprot, a relative permittivity of the oxide film is εsio, and a relative permittivity of the protection film is εprot.