Transparent Conductor Substrate Bonding Without Adhesive Defects
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Solution Overview
Problem
Existing semiconductor and electrooptical device bonding technologies require adhesives, which can introduce defects and limitations in bonding quality and efficiency, particularly in heterogeneous structures with differing thermal expansion coefficients and fine pitch requirements.
Innovation Solution
Direct hybrid bonding techniques are employed to bond optically transparent and electrically conductive/insulative layers without adhesives, using polished and activated surfaces, enabling covalent bonds and interdiffusion of conductive features at room temperature, allowing for fine pitch and heterogeneous material combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesives are used for bonding semiconductor and electrooptical devices, then bonding can be achieved, but defects are introduced and thermal expansion mismatch limitations occur
Solution Approach 1:
The patent removes adhesives from the bonding process entirely, extracting the harmful element that causes defects and thermal expansion limitations. Direct hybrid bonding is implemented between conductive and nonconductive regions without any adhesive layer, eliminating the source of reliability issues.
Solution Approach 2:
The invention uses composite bonding surfaces that include both conductive and nonconductive regions on the same wafer or die. This hybrid structure allows different materials to be bonded directly to each other, enabling thermal and mechanical compatibility without adhesives while maintaining electrical conductivity where needed.
2Reliability
If direct bonding is implemented without adhesives, then defects are eliminated, but maintaining optical transparency and electrical conductivity becomes challenging
Solution Approach 1:
The patent applies local quality by creating distinct conductive and nonconductive regions on bonding surfaces. Conductive pads or regions are positioned precisely where electrical connection is needed, while nonconductive regions provide mechanical bonding and insulation. This localized differentiation allows the bonded structure to maintain both optical transparency and electrical conductivity in appropriate areas.
Solution Approach 2:
The bonding surface is segmented into multiple functional regions - conductive areas for electrical connection and nonconductive areas for mechanical bonding and insulation. This segmentation allows each region to be optimized for its specific function while contributing to the overall performance of the bonded structure.
3Productivity
If conductive regions are made smaller for fine pitch applications, then device density increases, but bonding reliability becomes more difficult to maintain
Solution Approach 1:
The patent performs preliminary actions by preparing the bonding surfaces in advance with precisely patterned conductive and nonconductive regions. Surface activation treatments are applied beforehand to ensure optimal bonding conditions. This preliminary preparation allows fine-pitch conductive regions to be bonded reliably without compromising connection strength or electrical performance.
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 method achieves strong, adhesive-free bonds with minimal defects, enabling high-density electrical connections and optical transparency, suitable for diverse semiconductor and electrooptical devices, including those with varying thermal expansion coefficients and fine pitch requirements.
Implementation Method 1
using polished and activated surfaces with covalent bonding
Data Source
AI summary
An element includes a substrate and a surface layer on the substrate. The surface layer includes at least one first region comprising an optically transparent and electrically insulative first material and at least one second region at least partially embedded in the at least one first region. The at least one second region comprises an optically transparent and electrically conductive second material.