Semiconductor Microbump Surface Smoothing for 3D Lamination Alignment
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Solution Overview
Problem
In three-dimensional semiconductor packaging, position misalignment issues arise during the lamination and bonding of semiconductor chips, particularly when using microbumps, which can lead to reduced bonding strength and accuracy.
Innovation Solution
A method involving a smooth surface formation process on microbumps, followed by lamination and bonding in a reducing atmosphere, where the microbumps are collectively molten to ensure accurate positioning and prevent repeated heating, utilizing a pressure application member to deform and remove voids, thereby enhancing alignment and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If multiple semiconductor chips are laminated and bonded using microbumps, then wiring length is dramatically shortened and wiring delay time is reduced, but position misalignment between semiconductor chips occurs
Solution Approach 1:
The patent applies preliminary action by forming a smooth surface on the microbump before the lamination process. This pre-processing step creates a standardized, flat surface that facilitates accurate positioning during subsequent chip stacking, preventing misalignment issues that would otherwise occur with conventional microbump structures.
Solution Approach 2:
The patent changes the surface parameter of the microbump by creating a smooth surface through preliminary processing. This parameter change transforms the microbump from a potentially irregular surface to a controlled, flat surface, enabling precise alignment during lamination while maintaining the short wiring length benefit.
2Strength
If semiconductor chips are bonded by melting microbumps through heating, then bonding strength is achieved, but repeated heating reduces the strength of the bonded portion
Solution Approach 1:
The patent performs preliminary processing to create a smooth surface on the microbump before bonding. This pre-prepared surface enables more efficient and uniform heating during the bonding process, allowing the microbump to melt and bond in a single heating cycle rather than requiring multiple heating operations, thereby preserving bonded portion strength.
Solution Approach 2:
The patent replaces the conventional mechanical pressing and multi-step bonding process with a streamlined thermal process. By creating a smooth surface preliminarily, the bonding can be achieved through controlled heating that melts the microbump once, eliminating the need for repeated mechanical adjustments and heating cycles that would weaken the bond.
3Loss of time
If microbumps are used for chip coupling, then wiring delay time is reduced, but oxide films on microbump surfaces interfere with bonding quality
Solution Approach 1:
The patent applies preliminary action by processing the microbump surface before bonding to remove oxide films and create a smooth surface. This pre-cleaning step ensures that when heating occurs during bonding, the exposed fresh metal surfaces can bond effectively without oxide interference, maintaining both the speed and reliability benefits of microbump coupling.
Solution Approach 2:
The patent converts the potential harm of oxide films into a benefit by using the preliminary processing step to selectively remove oxides only from the critical bonding surfaces of the microbumps. This targeted removal preserves the short wiring length advantage while eliminating the bonding quality issues caused by oxide contamination.
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 allows for accurate positioning and bonding of multiple semiconductor chips with improved strength by removing voids and oxide films, reducing misalignment and maintaining bonding integrity.
Implementation Method 1
a smooth surface formation process of forming a smooth surface on the microbump
Implementation Method 2
a bonding process of bonding the semiconductor chips to each other via the microbumps by heating to melt the microbumps
Implementation Method 3
the microbumps are collectively molten to ensure accurate positioning and prevent repeated heating, utilizing a pressure application member to deform and remove voids
Implementation Method 4
by an action of surface tension of the microbump that has been liquefied, a position misalignment between one of the semiconductor chips and the other one of the semiconductor chips (self-alignment effect)
Data Source
AI summary
A method for producing a semiconductor package in which a plurality of semiconductor chips, each of which includes a substrate, conductive portions formed on the substrate, and microbumps formed on the conductive portions, are laminated, which includes a smooth surface formation process of forming a smooth surface on the microbump, a lamination process of laminating three or more of the semiconductor chips by overlaying the microbump of one of the semiconductor chips on the microbump of another one of the semiconductor chips, and a bonding process of bonding the semiconductor chips to each other via the microbumps by heating to melt the microbumps, in which in the lamination process, of one of the semiconductor chips and another one of the semiconductor chips, the smooth surface is formed on at least one of the microbump, and one of the microbump contacts another one of the microbump on the smooth surface.