Optical Waveguide Element Substrate Removal for Bonding Integrity
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Solution Overview
Problem
Optical modulation elements with thinly processed substrates face issues with substrate cracking and connection failures during electrical connections, leading to reduced manufacturing yield due to applied pressures from bonding processes.
Innovation Solution
An optical waveguide element design featuring a support substrate with substrate removal portions that allow electrical connections to be formed on the support substrate instead of the thinly processed optical substrate, reducing the risk of cracking and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the substrate is thinly processed to reduce device size, then the optical modulation element can be miniaturized, but substrate cracking may occur during electrical connection
Solution Approach 1:
The substrate is segmented into a light-transmitting region and a light-nontransmitting region (substrate removal portion). This segmentation allows the thin substrate to be maintained in the optical region for miniaturization while removing material in the connection region to prevent cracking during electrical bonding operations.
Solution Approach 2:
The substrate material is extracted (removed) in the light-nontransmitting region where electrical connections are made. This extraction eliminates the fragile thin substrate portion from the bonding area, preventing cracking while preserving the thin substrate structure in the optical region for device miniaturization.
2Productivity
If the substrate is thinly processed to improve light confinement, then interaction efficiency between light and electricity increases, but manufacturing yield decreases due to connection failures
Solution Approach 1:
The substrate is divided into functional zones: a light-transmitting region with thin substrate for efficient light-electricity interaction, and a light-nontransmitting region with substrate removal for reliable electrical connection. This segmentation enables both high interaction efficiency and manufacturing yield.
Solution Approach 2:
Different regions of the substrate have different qualities: the light-transmitting region maintains thin substrate for optical performance, while the light-nontransmitting region has substrate removed for mechanical strength during bonding. This local differentiation resolves the contradiction between interaction efficiency and manufacturing yield.
3Ease of manufacture
If wire bonding or flip-chip bonding is performed on a thin substrate, then electrical connection is achieved, but peeling or cracking occurs due to applied pressure
Solution Approach 1:
The substrate is removed in the light-nontransmitting region to create a substrate removal portion. This extraction eliminates the weak thin substrate from the bonding area, allowing wire bonding or flip-chip bonding to be performed without applying pressure to the fragile substrate, thereby preventing peeling and cracking.
Solution Approach 2:
The substrate removal portion acts as an intermediary structure that enables electrical connection without direct pressure on the thin substrate. The conductor pattern is formed on the support substrate through the removed portion, allowing bonding to occur on a stable surface rather than on the fragile thin substrate.
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
Prevents substrate cracking and connection failures during electrical bonding, enhancing the manufacturing yield and reliability of optical waveguide devices by distributing bonding pressures across a stronger support substrate.
Implementation Method 1
an optical modulation element using LiNbO3 (hereinafter, also referred to as LN) having an electro-optic effect for a substrate
Data Source
AI summary
In an optical modulation element using a thinly processed substrate, cracking of the substrate during electrical connection is prevented, and poor connection or a reduction in manufacturing yield is prevented. An optical waveguide element includes an optical substrate on which an optical waveguide and a conductor pattern are formed, and a support substrate that supports the optical substrate, in which the conductor pattern includes at least one electrical connection area defined as a range in which electrical connection is performed, the optical substrate has a substrate removal portion in which a material of the optical substrate has been removed to penetrate through the optical substrate at a portion corresponding to the electrical connection area, and at least a part of the electrical connection area is formed on the support substrate via the substrate removal portion.