Integrated Photodetector Layout for Stable ESD Protection
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Solution Overview
Problem
Photodetectors with protection zener diodes are susceptible to positional deviations during manufacturing, which affect the rectification characteristics due to the use of different semiconductor materials for the Ge layer and Si layer.
Innovation Solution
A photodetector design where the photodiode and protection diode are integrated on the same semiconductor substrate, with the protection diode using the same semiconductor material as the photodiode, ensuring no positional deviation between the light-absorbing layer and the pn or pin junction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection zener diode is formed using both Ge layer and Si layer with ion implantation, then electrostatic discharge protection is provided, but positional deviation between light-absorbing layer and semiconductor portions occurs affecting rectification characteristics
Solution Approach 1:
The patent merges the protection diode structure with the photodiode structure by forming both the light-absorbing layer and the semiconductor portions of the protection diode using the same Ge layer on the same Si core layer. This integration eliminates the need for separate Ge layer formation and ion implantation steps that would cause positional deviations, thereby maintaining manufacturing precision while providing electrostatic discharge protection.
Solution Approach 2:
The Ge layer serves multiple functions simultaneously: it acts as the light-absorbing layer for the photodiode and as the semiconductor material for the protection diode's semiconductor portions. This multi-functionality eliminates the need for separate material layers and alignment steps, resolving the contradiction between providing protection and maintaining manufacturing precision.
2Adaptability or versatility
If separate Ge layer and Si layer are formed using mask-based ion implantation, then protection circuit functionality is achieved, but manufacturing complexity and alignment errors increase
Solution Approach 1:
The patent combines the formation of the light-absorbing layer and the protection diode semiconductor portions into a single Ge layer formation process. This merging eliminates the need for multiple mask-based ion implantation steps, reducing manufacturing process complexity while maintaining the required protection circuit functionality.
Solution Approach 2:
The same Ge layer is used to provide both photodetection functionality and protection circuit functionality, eliminating the need for separate material layers and complex manufacturing steps. This universal use of the Ge layer simplifies the overall device structure and manufacturing process.
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 design eliminates the influence of positional deviations on the rectification characteristics of the photodetector, enhancing its reliability and performance.
Implementation Method 1
The semiconductor portion of the protection diode includes only one type of semiconductor material used for the semiconductor portion of the photodiode
Implementation Method 2
a p-type semiconductor portion, an n-type semiconductor portion (pn junction), or a p-type semiconductor portion, an intrinsic semiconductor portion, and an n-type semiconductor portion (pin junction)
Data Source
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AI summary
A photodetector of the present invention includes: a photodiode; and a protection diode. The photodiode and the protection diode are integrated on a same semiconductor substrate. The photodiode includes a semiconductor portion made of at least one type of semiconductor material, an anode electrode, and a cathode electrode. The protection diode includes a core layer, a semiconductor portion provided in the core layer and including a first-type semiconductor region doped with first-type impurity ions and a second-type semiconductor region doped with second-type impurity ions, an anode electrode, and a cathode electrode. The semiconductor portion of the protection diode includes only one type of semiconductor material used for the semiconductor portion of the photodiode. The anode electrodes of the protection diode and the photodiode are connected to each other. The cathode electrodes of the protection diode and the photodiode are connected to each other.