Stacked Semiconductor Display Bonding With Localized Heating
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Solution Overview
Problem
Existing head-mounted display devices face challenges in providing high-resolution images due to heat-induced damage during the bonding process of semiconductor substrates, which affects the performance and reliability of the display elements.
Innovation Solution
The use of a heating line that bypasses bonding pads and surrounds them, allowing for localized heat transfer during the bonding process of two different single crystal semiconductor substrates, reducing damage to light emitting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional heating methods are used during bonding process, then bonding efficiency is improved, but heat-induced damage to light emitting elements occurs
Solution Approach 1:
The heating line is segmented into multiple independent heating regions that correspond to different bonding pads. Each heating region can be controlled independently to provide localized heating only where needed for bonding, while leaving other areas (including light emitting elements) cool. This segmentation allows bonding efficiency to be maintained through active heating zones while preventing heat damage to sensitive areas.
Solution Approach 2:
The heating line is designed with spatially varying thermal properties - the regions above bonding pads have high thermal conductivity and low thermal resistance to efficiently transfer heat for bonding, while regions above light emitting elements have reduced thermal coupling to minimize heat damage. This local differentiation of thermal quality enables simultaneous bonding efficiency and protection of sensitive components.
2Use of energy by moving object
If heating line overlaps with bonding pads, then heat transfer efficiency is improved, but damage to light emitting elements increases
Solution Approach 1:
The harmful thermal coupling between the heating line and light emitting elements is extracted and eliminated by designing the heating line to bypass the bonding pads rather than overlap with them. The heating line is routed through non-display areas or through holes in the substrate, completely separating the heating path from the light emitting elements. This extraction of the heating function from the bonding pad areas maintains heat transfer efficiency for bonding while preventing thermal damage to light emitting elements.
Solution Approach 2:
Through holes in the substrate serve as intermediaries that allow the heating line to be positioned above bonding pads without direct thermal coupling to light emitting elements. The through holes act as thermal barriers or routing paths that enable the heating line to transfer heat to bonding pads while preventing heat from reaching adjacent light emitting elements, thus mediating between the need for efficient heating and the need to protect sensitive components.
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 approach enhances the bonding process by minimizing heat-induced damage, thereby improving the reliability and performance of high-resolution displays in head-mounted devices.
Implementation Method 1
a heating line around the plurality of bonding pads, each of both ends of the plurality of bonding pads being connected to a heating contact portion
Data Source
AI summary
A display device includes: a first single crystal semiconductor substrate in which a plurality of first transistors is formed; a second single crystal semiconductor substrate on the first single crystal semiconductor substrate, and on which a display element layer that includes a plurality of light emitting elements is located; a connection wiring layer between the first single crystal semiconductor substrate and the second single crystal semiconductor substrate; a plurality of through holes in the second single crystal semiconductor substrate, and in which vias connected to connection lines of the connection wiring layer are located; a plurality of bonding pads on the first single crystal semiconductor substrate, the bonding pads being connected to the connection lines and spaced from each other; and a heating line around the plurality of bonding pads, each of both ends of the bonding pads being connected to a heating contact portion.