Optical modulation element

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Solution Overview

Problem

Conventional optical modulation elements face a high risk of micropeeling at the outer peripheral end portions of the substrate during the wafer cutting process, leading to reduced reliability due to peeling of constituent layers.

Innovation Solution

The optical modulation element incorporates a dielectric layer with an offset area positioned inside the outer peripheral end portions of the substrate and waveguide layer, ensuring that the dielectric layer's outer peripheral end portion is aligned within the substrate's outer peripheral end portion, thereby preventing micropeeling during the cutting process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the lower clad layer is cured before application of waveguide layer material, then the lower clad layer cannot serve as an adhesive, but this causes peeling at the interface between the lower clad layer and the waveguide layer during cutting operation

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidlayer adhesion stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by forming the waveguide layer before curing the lower clad layer. This sequence allows the lower clad layer to serve as an adhesive during the waveguide layer formation process, preventing peeling at the interface during subsequent cutting operations. The waveguide layer is formed on the uncured lower clad layer, which then cures to provide strong adhesion.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the waveguide layer is formed through epitaxial growth, then peeling of the waveguide layer does not become a major problem, but in optical modulation elements with complicated layer structure for higher performance, there is a high risk of peeling of constituent layers other than the waveguide layer

Engineering Contradiction:

Improvewaveguide layer adhesionVSAvoidlayer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the dielectric layer extends to the outer peripheral end portion of the substrate, then the dielectric layer provides full coverage, but this causes micropeeling at the outer peripheral end portion during wafer cutting

Engineering Contradiction:

Improvedielectric layer coverageVSAvoidmicropeeling during cutting

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies the taking out principle by removing the dielectric layer from the outer peripheral end portion of the substrate. Specifically, the dielectric layer is formed only in a region where its outer peripheral end portion is positioned inside the outer peripheral end portion of the substrate, excluding the cutting edge area. This extraction of the dielectric layer from the problematic region prevents micropeeling during wafer cutting while maintaining full coverage in the functional areas.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12429719B2Optical modulation element

Publication Date: 2025.09.30 TDK CORP

AI summary

An optical modulation element is provided with a substrate, a waveguide layer formed on the substrate, a dielectric layer formed on the waveguide layer, and an electrode formed on the dielectric layer. An outer peripheral end portion of the dielectric layer has an offset area positioned inside an outer peripheral end portion of the substrate. In at least a part of the offset area, a distance from the outer peripheral end portion of the substrate to the outer peripheral end portion of the dielectric layer is equal to or less than a distance from the outer peripheral end portion of the substrate to the outer peripheral end portion of the electrode.