Carrier-Based Warpage Control for 3DIC Stacking
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Summary
Problems
Conventional Package-on-Package (PoP) device fabrication processes fail to adequately prevent warping, especially when stacking relatively thin integrated circuit dies, due to material coefficient of thermal expansion mismatches.
Innovation solutions
A method involving the use of a carrier with a low coefficient of thermal expansion, such as glass or silicon, to temporarily mount substrates and dies, followed by pressure annealing, underfill material application, and molding to inhibit warping, while allowing for horizontal offset stacking and subsequent removal of the carrier.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If conventional fabrication processes are used to stack packages, then the manufacturing process is simple, but the packages warp due to thermal expansion mismatches
Why choose this principle:
A carrier substrate is introduced as an intermediary component during the stacking process. This carrier has a low coefficient of thermal expansion that acts as a stable reference plane, preventing warping of the stacked packages. The carrier is temporarily used during assembly and then removed, serving as a mediator that enables precise stacking without introducing permanent structural changes to the final product.
Principle concept:
If conventional fabrication processes are used to stack packages, then the manufacturing process is simple, but the packages warp due to thermal expansion mismatches
Why choose this principle:
The process utilizes controlled temperature changes during pressure annealing to reduce warpage. By heating the stacked packages on the carrier to elevated temperatures and then cooling them under pressure, the thermal expansion differences between materials are minimized, allowing the packages to conform to the carrier's flat surface and reducing warpage.
Application Domain
Data Source
AI summary:
A method involving the use of a carrier with a low coefficient of thermal expansion, such as glass or silicon, to temporarily mount substrates and dies, followed by pressure annealing, underfill material application, and molding to inhibit warping, while allowing for horizontal offset stacking and subsequent removal of the carrier.
Abstract
An embodiment method of forming a package-on-package (PoP) device includes temporarily mounting a substrate on a carrier, stacking a first die on the substrate, at least one of the die and the substrate having a coefficient of thermal expansion mismatch relative to the carrier, and stacking a second die on the first die. The substrate may be formed from one of an organic substrate, a ceramic substrate, a silicon substrate, a glass substrate, and a laminate substrate.