PIN Photodiode Electrode Extraction and Antireflection Coating
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Solution Overview
Problem
PIN photodiodes face a trade-off in achieving high photoelectric conversion efficiency for blue light, as electrodes within the light receiving plane block incident light, reducing carrier generation, while electrodes outside the plane increase carrier travel distance and recombination, leading to decreased efficiency.
Innovation Solution
A photodiode manufacturing method involving a high concentration silicon region formed at a prescribed depth from the surface, with a silicon oxide film and antireflection film to minimize light reflection and recombination, and electrodes positioned outside the light receiving plane to maximize incident light, combined with a silicon nitride film optimized for blue light wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are positioned within the light receiving plane, then electrical connection is achieved, but incident light is blocked and carrier generation is reduced
Solution Approach 1:
The patent moves electrodes from the two-dimensional light receiving plane to the peripheral region, utilizing the third dimension (vertical placement) and edge regions to achieve electrical connection without blocking incident light on the active area
Solution Approach 2:
The electrodes are extracted from the light receiving plane and repositioned to the peripheral region, separating the electrical connection function from the light reception function to eliminate mutual interference
2Productivity
If electrodes are positioned outside the light receiving plane, then incident light is maximized, but carrier travel distance increases and recombination increases
Solution Approach 1:
The patent creates a high concentration impurity region locally beneath the electrodes to form an efficient carrier collection path, reducing the effective travel distance for carriers even though electrodes are positioned peripherally
3Productivity
If silicon surface is exposed, then light reception is maximized, but recombination occurs due to high recombination speed at silicon surface
Solution Approach 1:
The patent introduces a silicon oxide film as an intermediary layer between the silicon surface and the external environment, which passivates the silicon surface to reduce recombination while maintaining light reception capabilities
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 enhances photoelectric conversion efficiency to near theoretical thresholds while maintaining response speed, enabling precise data reading and writing in optical pickups.
Implementation Method 1
silicon oxide film and antireflection film to minimize light reflection
Implementation Method 2
converts incident light to a photocurrent
Implementation Method 3
antireflection film made of silicon nitride film optimized for blue light wavelengths
Data Source
AI summary
The objective of this invention is to provide a type of photodiode and the method of manufacturing the photodiode characterized by the fact that it has a higher photoelectric conversion efficiency (sensitivity) than that in the prior art. PIN photodiode 100 has a p-type silicon substrate, p-type silicon layer 112, n-type silicon layer 114 formed on p-type silicon layer 112 and having a junction plane with silicon layer 112, n-type low-resistance silicon region 116 that is formed to a prescribed depth from the surface of silicon layer 114 and has an impurity concentration higher than that of silicon layer 114, silicon oxide film 120 formed on silicon region 116, and silicon nitride film 122 formed on silicon oxide film 120.