Integrated Capacitor Light Detector Parasitic Noise Reduction
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Solution Overview
Problem
Existing light detecting apparatuses suffer from degraded noise and high-frequency characteristics due to parasitic capacitance generated when components are mounted on a printed circuit board, leading to increased noise and reduced signal-to-noise ratios.
Innovation Solution
The light detecting apparatus features a capacitance component functioning as a coupling capacitor directly formed on a semiconductor substrate, with electrode layers arranged to minimize parasitic capacitance by being electrically connected to the semiconductor regions, thereby reducing noise and enhancing high-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual components such as the light receiving element and chip capacitor are mounted on a printed circuit board, then the impedance can be made smaller on the light receiving element side and the equivalent input noise level can be reduced, but parasitic capacitance is generated in each of the components and wires on the printed circuit board, causing noise and high-frequency characteristics to degrade
Solution Approach 1:
The patent merges the coupling capacitor function with the semiconductor substrate by forming the capacitor directly on the substrate using electrode layers. This integration eliminates the need for separate chip capacitors and their connecting wires, thereby removing the parasitic capacitance sources while maintaining the noise reduction benefit
Solution Approach 2:
The patent introduces an insulating layer as an intermediary between the electrode layers to form the coupling capacitor. This insulating layer serves as the dielectric medium that enables capacitance formation while minimizing parasitic effects, acting as a mediator that achieves the desired electrical isolation and capacitance function without the harmful parasitic capacitance of traditional mounted components
2Productivity
If a chip capacitor is adopted as the coupling capacitor and individual components are mounted on a printed circuit board, then the impedance can be reduced, but noise and high-frequency characteristics degrade due to parasitic capacitance
Solution Approach 1:
The patent combines the coupling capacitor function directly into the semiconductor substrate structure, eliminating the need for separate chip capacitors. This merging achieves impedance reduction without introducing the parasitic capacitance that would degrade high-frequency characteristics
Solution Approach 2:
The patent transitions from a three-dimensional mounted component configuration to a planar integration approach by forming the coupling capacitor within the semiconductor substrate itself. This dimensional change eliminates wire connections and mounting parasitics, preserving high-frequency performance while achieving the required impedance reduction
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 results in a light detecting apparatus with improved noise and high-frequency characteristics by minimizing parasitic capacitance, preventing degradation of signal quality and allowing for better light incidence without external noise interference.
Implementation Method 1
a semiconductor substrate having a first conductivity type first semiconductor region, and a second conductivity type second semiconductor region formed on the first semiconductor region and constituting a photodiode based on a pn junction
Implementation Method 2
a second electrode layer arranged above the first electrode layer so as to be opposed to the first electrode layer, and forming a capacitance component connected to the photodiode, between the first electrode layer and the second electrode layer
Data Source
AI summary
A light detecting apparatus is provided with a semiconductor substrate, a first electrode layer, and a second electrode layer. The semiconductor substrate has a first conductivity type first semiconductor region, and a second conductivity type second semiconductor region formed on the first semiconductor region and constituting a photodiode based on a pn junction formed between the first semiconductor region and the second semiconductor region. The first electrode layer is arranged above the second semiconductor region so as to be opposed to the second semiconductor region and is electrically connected to the second semiconductor region. The second electrode layer is arranged above the first electrode layer so as to be opposed to the first electrode layer and forms a capacitance component connected to the photodiode, between the first electrode layer and the second electrode layer.