Package-on-Package Bonding With Deformed Conductive Bumps
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Solution Overview
Problem
The semiconductor industry faces limitations in increasing circuit density due to physical constraints in two-dimensional integrated circuits, prompting the exploration of three-dimensional ICs, but existing 3D IC formation processes are complex and inefficient.
Innovation Solution
A package-on-package structure manufacturing method involving a carrier substrate with an adhesive layer, redistribution structures, and conductive bumps, where conductive bumps are deformed to increase bonding strength and facilitate the stacking of packages, using a tape carrier to simplify the bonding and singularizing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If two dies are bonded together to form 3D IC, then circuit density is increased, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into distinct stages: forming conductive bumps on first dies, bonding first dies to carrier substrate, forming conductive bumps on second dies, bonding second dies to first dies, and finally singularizing the stacked dies. This segmentation allows each stage to be optimized independently, reducing overall manufacturing complexity while achieving high circuit density through 3D stacking.
Solution Approach 2:
A carrier substrate is introduced as an intermediary element to temporarily hold and align multiple dies during the bonding process. The carrier substrate provides a stable platform for forming and aligning conductive bumps, enabling precise registration between stacked dies without requiring complex direct alignment mechanisms, thus reducing manufacturing complexity.
2Reliability
If wire bonds are used to electrically couple contact pads, then electrical connections are established, but manufacturing time increases
Solution Approach 1:
Conductive bumps are formed on the dies before bonding, and carrier substrate with pre-formed contact pads are prepared in advance. This preliminary formation of electrical connection structures eliminates the need for time-consuming wire bonding operations after die stacking, as electrical connections are already established through the conductive bumps and carrier substrate contact pads.
3Strength
If conventional bonding process is used, then dies are stacked, but bonding strength is insufficient
Solution Approach 1:
The bonding process parameters are changed by applying both heat and pressure simultaneously during the die stacking process. This thermal compression bonding approach, with controlled temperature and pressure parameters, creates strong bonds between dies and carrier substrate without requiring complex bonding equipment or multi-step processes, thus maintaining ease of manufacture while achieving high bonding strength.
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 enhances the yield and reduces costs by improving bonding strength and simplifying the manufacturing process for 3D packaging, allowing for more efficient integration of semiconductor devices in a three-dimensional format.
Implementation Method 1
a first package is attached to a carrier substrate through an adhesive layer
Implementation Method 2
a second package is coupled to the first package opposite to the plurality of conductive bumps to form a package on package structure, where the plurality of conductive bumps is deformed
Data Source
AI summary
A manufacturing method of a package-on-package structure includes at least the following steps. Top packages are mounted on a top side of a reconstructed wafer over a flexible tape, where conductive bumps at a bottom side of the reconstructed wafer is attached to the flexible tape, and during the mounting, a shape geometry of the respective conductive bump changes and at least a lower portion of the respective conductive bump is embraced by the flexible tape. The flexible tape is released from the conductive bumps after the mounting.