SPAD Guide Wall Structure for Higher Photon Detection Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional SPAD structures suffer from reduced Photon Detection Efficiency (PDE) due to photogenerated electrons being diffused to the side surfaces of the PN junction region instead of the avalanche region, leading to inefficient photon detection.
Innovation Solution
The formation of a guide wall on the side portions of the first and second impurity doped regions in the SPAD structure to direct photogenerated charges to the avalanche region, along with a guard ring to prevent diffusion to the side portions and lower dark count rates, and doping the second region with lower impurity concentration to enhance charge diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional SPAD structure without guide wall is used, then the structure is simple, but photogenerated electrons are diffused to side surfaces of the PN junction region instead of reaching the avalanche region, reducing Photon Detection Efficiency
Solution Approach 1:
The device is segmented into distinct functional regions: a first impurity doped region, a second impurity doped region, and guide walls formed on side portions. This segmentation creates clear charge collection paths while maintaining structural organization, directly addressing the PDE improvement goal.
Solution Approach 2:
Guide walls are selectively formed only on the side portions of the first and second impurity doped regions, not throughout the entire device. This localized structural modification directs photogenerated charges toward the avalanche region while minimizing unnecessary complexity in other areas.
2Reliability
If the second impurity doped region is doped with high impurity concentration, then the region has good electrical contact, but photogenerated charges cannot be effectively diffused to the avalanche region
Solution Approach 1:
The impurity concentration in the second impurity doped region is specifically controlled to be lower than in the first impurity doped region. This parameter change enables effective charge diffusion to the avalanche region while maintaining sufficient electrical contact, resolving the contradiction between diffusion efficiency and contact quality.
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 solution increases Photon Detection Efficiency (PDE) by guiding photogenerated charges to the avalanche region, prevents diffusion to the side portions, and reduces dark count rates.
Implementation Method 1
a guide wall is formed on side portions of a first impurity doped region and a second impurity doped region so as to induce photogenerated charges to be diffused to an avalanche region
Implementation Method 2
Since a voltage exceeding the breakdown voltage is applied to a SPAD, an electron avalanche occurs due to carriers generated by photoelectric conversion
Implementation Method 3
an electron avalanche occurs due to carriers generated by photoelectric conversion, and the SPAD enters a breakdown state
Data Source
AI summary
Proposed are a Single Photon Avalanche Diode (SPAD) structure and a manufacturing method thereof. More particularly, the SPAD structure is configured such that a guide wall is formed on side portions of a first impurity doped region and a second impurity doped region so as to induce photogenerated charges to be diffused to an avalanche region on a PN junction region between the first impurity doped region and the second impurity doped region, thereby increasing Photon Detection Efficiency (PDE).