LED Printhead Inter-layer Insulating Film Stress Absorber
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Solution Overview
Problem
In semiconductor devices used in LED printheads, the edge portions of opening portions in inter-layer insulating films concentrate stresses, leading to potential cracks in the semiconductor thin film and peeling off of contact electrodes.
Innovation Solution
A stress-absorbing portion is provided along the edge of the opening portion in the inter-layer insulating film, which can be formed as an inclined surface or a thin insulating film, covering the edge and extending inside, to reduce stress concentration and prevent cracking and peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an opening portion is formed in the inter-layer insulating film to expose the contact layer for electrical connection, then electrical connectivity is achieved, but stress concentration occurs at the opening edge causing cracks or peeling
Solution Approach 1:
The patent applies local quality by creating a recessed region specifically at the opening edge of the inter-layer insulating film. This localized structural modification concentrates the stress-absorbing function at the critical stress concentration point without affecting other regions of the device, thereby maintaining electrical connectivity while preventing cracks and peeling at the opening edge.
Solution Approach 2:
The recessed region acts as a stress-absorbing structure that beforehand cushions the stress applied to the opening edge. By providing this protective feature in advance, the patent prevents stress concentration from causing cracks in the semiconductor thin film or peeling of the contact electrode, thus protecting the structural integrity before failure can occur.
2Manufacturing precision
If the opening edge is formed as an orthogonally-crossing surface for precise fabrication, then manufacturing precision is improved, but stress concentration increases leading to device failure
Solution Approach 1:
The patent maintains the orthogonally-crossing surface for precise fabrication in the main body of the opening, then locally modifies only the edge portion by forming a recessed region. This localized modification preserves manufacturing precision for the overall opening structure while specifically addressing the stress concentration issue at the critical edge area, thereby improving device reliability without sacrificing fabrication precision.
Data Source
AI summary
An inclined surface having an inclination angle θ is formed in an edge portion which forms an opening portion of an inter-layer insulating film, thereby reducing a stress by the inclined surface.