Via Contact Metallization for Thick Semiconductor Substrates
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Solution Overview
Problem
Existing methods for manufacturing via contacts in semiconductor substrates are inefficient for thicker wafers, as they require complex masking and additional processing steps, and do not effectively utilize the large surface area of the contact holes for conductive connections.
Innovation Solution
The method involves coating only the side walls and base of a contact hole with electrically conductive material, using standard CMOS processing steps, and depositing dielectric, metallization, and passivation layers, without filling the contact hole, to create via contacts with low ohmic resistance and simplified processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are filled with electrically conductive material and substrate is thinned to create via contacts, then electrical connection is achieved, but processing complexity increases and substrate integrity is compromised
Solution Approach 1:
The invention extracts the essential function of electrical connection from the traditional filled-contact-hole approach. Instead of filling the entire contact hole with conductive material and thinning the substrate, the patent uses conductive paste applied only to the bottom surface, eliminating the need for substrate thinning and complex filling processes while maintaining electrical connectivity.
Solution Approach 2:
The invention inverts the conventional approach by applying conductive material to the bottom surface of the substrate rather than filling from the top. The conductive paste is deposited on the rear surface and makes contact through vias, reversing the traditional top-down filling method and eliminating substrate thinning requirements.
2Reliability
If conventional via contact methods are used for thicker wafers, then processing complexity increases, but electrical connection is achieved
Solution Approach 1:
The conductive paste automatically fills the via holes through capillary action and self-alignment, eliminating the need for complex masking and filling processes. The paste is applied to the rear surface and naturally conforms to the via structures, providing self-aligned electrical connections without additional processing steps.
Solution Approach 2:
The invention changes the physical state and application method of the conductive material. Instead of using liquid metal that requires filling and solidification, the patent uses conductive paste that can be deposited as a thick film and naturally conforms to via structures, simplifying the manufacturing process for thick substrates.
3Reliability
If contact holes are coated with conductive material on side walls and base, then large surface area for conduction is achieved, but material deposition complexity increases
Solution Approach 1:
The conductive paste is applied in excessive amount to ensure complete coverage of the via holes and bottom surface. The paste naturally flows into and fills the via holes, providing robust electrical connection without requiring precise control of deposition thickness or complex multi-layer structures.
Solution Approach 2:
The invention uses composite conductive paste materials that combine conductive fillers with binding agents. This composite formulation allows the paste to be deposited as a thick film, naturally conform to via structures, and provide reliable electrical connection through both the side walls and bottom surface of the vias.
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 allows for the economical production of via contacts with typical diameters of 100 μm in substrates thicker than 100 μm, reducing processing complexity and achieving low ohmic resistance due to the large surface area of the side wall conductive connection, while maintaining the integrity of the passivation layer.
Implementation Method 1
an electrically conductive paste is applied in a thick film form onto a rear side of the substrate and the via holes are filled with the paste in an automatic self-aligned fashion
Data Source
AI summary
In an insulation layer of an SOI substrate, a connection pad is arranged. A contact hole opening above the connection pad is provided on side walls and on the connection pad with a metallization that is contacted on top side with a top metal.