TSV Bonding Protective Layer Prevents Short Circuits
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Solution Overview
Problem
The use of no-flow underfill in bonding semiconductor structures can lead to short circuits due to the flow of contact bump material into openings, causing defects and potential device failure.
Innovation Solution
A semiconductor bonding method involving a protective layer over the contact bumps and a buffer layer between the substrates, which prevents the contact bump material from extending through voids and short-circuiting to the substrate surfaces, using materials like polyimide, benzocyclobutene, or silicon nitride, and thermo-compression bonding to align and bond the substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If no-flow underfill is used during bonding, then the bonding process is simplified and productivity is improved, but contact bump material may flow into openings and cause short circuits
Solution Approach 1:
A protective layer is introduced as an intermediary element between the contact bumps and the substrate surface. This protective layer prevents direct contact between molten contact bump material and the substrate, eliminating the short circuit pathway while allowing the bonding process to proceed with no-flow underfill.
Solution Approach 2:
The protective layer is formed in advance before the bonding process occurs. By pre-establishing this protective barrier, the design ensures that when reflow heating occurs during bonding, the contact bump material cannot flow into openings and create short circuits, even though no-flow underfill is used.
2Reliability
If contact bumps are exposed without protection, then electrical contact is established, but material may flow into voids and create defects
Solution Approach 1:
The protective layer is applied selectively to specific regions where short circuit risk exists, while maintaining local exposure of contact bumps where electrical contact is needed. This localized approach ensures electrical functionality is preserved while preventing harmful material flow into voids and openings.
Solution Approach 2:
The protective layer serves as a mediating structure that allows electrical contact to be established through controlled pathways while blocking uncontrolled material flow into voids. It acts as a selective barrier that permits necessary electrical connectivity while preventing harmful short circuit pathways.
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 significantly reduces the risk of short circuits and damage, increasing the yield of usable devices by isolating the substrate surfaces and enhancing the bonding process with reduced voids and improved adhesion.
Implementation Method 1
A protective layer is formed over the contact bumps... the protective layer prevents the contact bump material from extending through voids and short-circuiting to the surface of the substrates
Implementation Method 2
thermo-compression bonding to align and bond the substrates
Data Source
AI summary
System and method for bonding semiconductor substrates is presented. A preferred embodiment comprises forming a buffer layer over a surface of a semiconductor substrate while retaining TSVs that protrude from the buffer layer in order to prevent potential voids that might form. A protective layer is formed on another semiconductor substrate that will be bonded to the first semiconductor substrate. The two substrates are aligned and bonded together, with the buffer layer preventing any short circuit contacts to the surface of the original semiconductor substrate.