Optical-to-Electrical Converter Via Electrode Inductance
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Solution Overview
Problem
The integration of a capacitor with a semiconductor light-receiving device on a semiconductor substrate leads to increased inductance components from line patterns and bonding wires, limiting the operation frequency due to resonance frequency constraints, making it difficult for the device to operate stably at high frequencies.
Innovation Solution
The optical-to-electrical converter unit incorporates a via electrode extending from the front surface to the back surface of the substrate, connecting the capacitance element to the back electrode, reducing inductance and allowing for a higher resonance frequency by providing a reference potential directly through the substrate, rather than through bonding wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a capacitor is integrated on the semiconductor substrate together with a photodiode and optical waveguide, then the device size is reduced and capacitance is increased, but the inductance component from line patterns and bonding wires increases, limiting the operation frequency
Solution Approach 1:
The invention transitions from planar connections to three-dimensional vertical connections by forming via electrodes that penetrate through the substrate thickness direction. This dimensional change allows the capacitor to be connected to the back surface electrode through vertical paths rather than horizontal bonding wires, significantly reducing inductance while maintaining compact integration.
Solution Approach 2:
The invention extracts and eliminates the bonding wire component from the electrical connection path. By forming direct semiconductor-based via electrodes within the substrate, the external bonding wires are removed, thereby eliminating their associated inductance and improving the resonance frequency characteristics.
2Ease of manufacture
If bonding wires are used to connect the capacitor to external circuits, then ease of manufacture is improved, but inductance increases and resonance frequency decreases
Solution Approach 1:
The substrate itself serves as the connection medium by forming via electrodes directly within its structure. The semiconductor substrate performs the dual function of mechanical support and electrical connection, eliminating the need for external bonding wires and achieving self-contained high-frequency performance.
Solution Approach 2:
The invention merges the substrate structure with the electrical connection function. The via electrodes are formed as integral parts of the substrate fabrication process, combining the mechanical support function and electrical interconnection function into a single unified structure.
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 increases the operation frequency of the semiconductor light-receiving device by reducing inductance components and alleviating parasitic capacitance issues, enabling stable operation at higher bit rates without the need for bonding wires, thus enhancing the device's performance and miniaturization.
Implementation Method 1
a via electrode extending from the front surface to the back surface of the substrate, the via electrode connecting the capacitance element to the back electrode
Implementation Method 2
a light-receiving element including an optical absorption layer
Data Source
AI summary
An optical-to-electrical converter unit includes a substrate having front and back surfaces; an original waveguide unit; and an optical-to-electrical converter. The optical-to-electrical converter includes a light-receiving element optically coupled to the optical waveguide unit; a capacitance element including first and second conductive layers and an insulating layer disposed between the first and second conductive layers; an electrode pad electrically connected to the light-receiving element; a back electrode formed on the back surface of the substrate; and a via electrode extending from the front surface to the back surface of the substrate. The optical waveguide unit, the light-receiving element, the capacitance element, and the electrode pad are formed on the front surface. The first conductive layer of the capacitance element is electrically connected to the light-receiving element and the electrode pad. The second conductive layer of the capacitance element is electrically connected to the back electrode through the via electrode.