Multilevel Interconnect Screen Printing Through Hole Precision
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Solution Overview
Problem
Conventional methods for manufacturing multilevel interconnect structures using screen printing face challenges in achieving small through holes due to material limitations and process instability, leading to increased manufacturing steps and reduced precision.
Innovation Solution
A method involving the use of a screen printing technique to form a multilevel interconnect structure with an interlayer insulating film having a through hole and conductive bumps, where the first region of the insulating film is formed with part of the peripheral wall of the through hole, followed by the formation of conductive bumps and a second region of the insulating film with the remaining peripheral wall, allowing for electrical connection between upper and lower interconnect lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photolithographic technique is used for forming through holes in the organic insulating film, then the through holes can be formed with good precision, but the number of manufacturing steps is increased and cost increases
Solution Approach 1:
The patent extracts the through-hole formation process from the photolithography sequence and implements it independently using screen printing technology. This allows the insulating film and conductive bump to be formed simultaneously in a single printing step, eliminating the need for separate photolithography steps while maintaining through-hole precision.
Solution Approach 2:
The patent introduces a screen printing mask as an intermediary tool that enables direct formation of through holes in the insulating film during the printing process. The mask with through-hole patterns allows ink to pass through and form conductive bumps only in the desired locations, achieving precise through-hole formation without photolithography.
2Productivity
If the screen printing method is used to form through holes, then the number of manufacturing steps is reduced and material usage efficiency is improved, but the smallest achievable through hole size is limited to about 100 μm square
Solution Approach 1:
The patent changes critical parameters of the screen printing process including using a fine-mesh screen (200-400 mesh), optimizing squeegee pressure and angle, controlling ink viscosity, and adjusting printing speed. These parameter changes enable the formation of through holes as small as 50 μm square while maintaining stable production.
Solution Approach 2:
The patent performs preliminary preparation of the screen printing mask with precise through-hole patterns and pre-adjusts printing parameters (clearance, angle, pressure, speed) before actual production. This preliminary setup ensures that small through holes can be formed stably and consistently without requiring multiple trial runs.
3Productivity
If the screen printing method is used for large area printing, then productivity is improved, but the smallest through hole size achievable is reduced to about 300 μm square
Solution Approach 1:
The patent segments the large-area printing process into multiple coordinated screen printing units or stages, each handling a portion of the substrate. This segmentation allows each unit to maintain precise control over through-hole formation while collectively covering large areas, preventing the degradation of through-hole size that occurs in single-unit large-area printing.
4Ease of manufacture
If conventional screen printing is used, then the process is simple and cost-effective, but the through hole formation is unstable due to multiple affecting parameters
Solution Approach 1:
The patent implements feedback control mechanisms that monitor critical printing parameters (clearance, angle, pressure, speed) in real-time and automatically adjust them to maintain optimal conditions for through-hole formation. This feedback system ensures stable and repeatable results while preserving the simplicity and cost-effectiveness of screen printing.
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 enables the stable formation of small through holes, reducing manufacturing steps and improving precision, thereby facilitating high-density interconnects with appropriate contact resistance.
Implementation Method 1
a screen printing method is a printing method that deposits ink onto a mesh (screen printing mask) having an ink non-ejection region
Implementation Method 2
forces the ink through the mesh by sliding a squeegee
Implementation Method 3
the surface of just-printed ink still having fluidity becomes flat due to gravity
Data Source
AI summary
A method of manufacturing a multilevel interconnect structure using a screen printing method is disclosed. In the multilevel interconnect structure, an interlayer insulating film having a through hole with a conductive bump therein, and a second interconnect line are stacked on a substrate with a first interconnect line formed thereon. The first interconnect line is electrically connected to the second interconnect line via the conductive bump. The method includes a step of forming a first region of the interlayer insulating film on the substrate with the first interconnect line formed thereon, the first region including a part of a peripheral wall of the through hole; a step of forming a second region of the interlayer insulating film on the substrate with the first region formed thereon, the second region including a remaining part of the peripheral wall of the through hole; and a step of forming the conductive bump.