Two-Stage Electrode Structure for Optical Waveguide Devices
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Solution Overview
Problem
In optical waveguide devices, particularly those using LiNbO3 substrates, the proximity of two-stage electrodes to protruding optical waveguides can lead to complex uneven shapes, resulting in over-etching of the base layer and overhanging conductive layers during the etching process, which complicates the manufacturing and affects the reliability and efficiency of the optical modulation elements.
Innovation Solution
The optical waveguide device incorporates a working electrode structure with a first base layer of niobium, a first conductive layer, a second base layer of titanium, and a second conductive layer of gold, where the edge of the second base layer is covered by the second conductive layer, preventing over-etching and ensuring a stable electrode configuration. This configuration includes a wiring electrode with the second conductive layer extending from the working electrode, and the thickness and material selection are optimized to enhance electric field efficiency and prevent overhanging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the two-stage electrode is brought close to the protruding optical waveguide to increase electric field efficiency, then the operation speed and power consumption are improved, but a complicated and fine uneven shape exists on the substrate, causing over-etching of the base layer and overhanging of the conductive layer
Solution Approach 1:
The electrode structure is divided into two distinct stages: a first stage with a first base layer and first conductive layer, and a second stage with a second base layer and second conductive layer. This segmentation allows each stage to be optimized independently - the first stage can be positioned close to the waveguide for high electric field efficiency, while the second stage provides a stable platform that prevents etching issues, thus resolving the contradiction between reliability and manufacturing precision.
Solution Approach 2:
Different materials and structures are applied to different regions of the electrode. The first base layer uses a material optimized for electrical performance near the waveguide, while the second base layer uses a different material optimized for mechanical stability and etching resistance. This local differentiation allows the system to achieve both high electric field efficiency and precise manufacturing.
2Power
If the two-stage electrode is brought close to the protruding optical waveguide, then the interaction between signal electric field and waveguide light is strengthened, but the etching rate of the metal film becomes different in a plane of the substrate due to uneven distribution of the corrugated structure
Solution Approach 1:
The electrode is segmented into two stages with different base layer materials. The first stage can be optimally positioned for power efficiency, while the second stage's base layer is specifically designed with appropriate thickness and material properties to ensure uniform etching rate across the substrate plane, thereby resolving the contradiction between power consumption and etching uniformity.
Solution Approach 2:
By changing the material composition and thickness parameters of the two base layers, the system achieves optimal performance. The first base layer parameters are optimized for electrical performance, while the second base layer parameters are specifically adjusted to compensate for the uneven corrugated structure, ensuring uniform etching rate and resolving the manufacturing difficulty.
3Device complexity
If a metal film is etched in a patterning step with fine uneven shape on the substrate, then the electrode structure can be formed, but the base layer is excessively etched in a wide range, causing overhanging of the conductive layer
Solution Approach 1:
The electrode structure is segmented into two stages, where the second stage's base layer acts as a protective platform during etching. This segmentation prevents the conductive layer from overhanging by providing a stable second base layer that maintains proper layer alignment, thus resolving the contradiction between device complexity and manufacturing precision.
Solution Approach 2:
The two-stage electrode structure is designed in advance to prevent etching problems before they occur. The second base layer is positioned and configured beforehand to serve as a protective platform during the etching process, preventing over-etching and overhanging issues, thereby resolving the contradiction between structural complexity and layer alignment precision.
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 effectively prevents over-etching and overhanging, enabling high-frequency optical modulation with lower drive voltage and improved reliability by ensuring precise electrode formation and increased electric field efficiency, thus enhancing the performance and stability of the optical waveguide devices.
Implementation Method 1
an optical modulation element using LiNbO3 (hereinafter, also referred to as LN) having an electro-optic effect for a substrate can achieve high-frequency optical modulation characteristics
Data Source
AI summary
There is provided an optical waveguide device including: a substrate; an optical waveguide formed on the substrate; and a working electrode that controls a light wave propagating through the optical waveguide, in which the working electrode includes a first base layer made of a first material, a first conductive layer on the first base layer, a second base layer made of a second material different from the first material, which is on the first conductive layer, and a second conductive layer on the second base layer, and an edge of the second base layer is covered with the second conductive layer, in a cross-section perpendicular to an extending direction of the optical waveguide.