3D IC Package Structure for Warpage-Resistant Singulation
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving efficient three-dimensional (3D) integration of integrated circuit (IC) packages due to limitations in bonding IC chips directly onto substrates, leading to issues with thermal expansion mismatch and warpage during the singulation process.
Innovation Solution
The implementation of a method involving hybrid bonding of IC dies to a wafer, using dummy structures to overlay scribe lines and reduce thermal expansion mismatch, and forming encapsulants to minimize stress and warpage, while also optimizing the ratio of encapsulant area to IC die area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If IC chips are bonded directly onto substrates to achieve 3D integration, then integration density is improved, but thermal expansion mismatch and warpage occur during singulation
Solution Approach 1:
The patent introduces an interposer as an intermediary component between the IC chip and substrate. The interposer has a different thermal expansion coefficient that serves as a buffer, reducing thermal expansion mismatch. It also provides a larger bonding area that distributes stress, thereby minimizing warpage during singulation while enabling 3D integration.
Solution Approach 2:
The patent changes the thermal expansion parameter by selecting an interposer material with a specific thermal expansion coefficient that is intermediate between the IC chip and substrate materials. This parameter adjustment reduces the overall thermal expansion mismatch in the stacked structure, preventing warpage while maintaining high integration density.
2Area of stationary object
If interposers are used to redistribute ball contact areas, then bonding area is increased, but device complexity increases
Solution Approach 1:
The interposer performs multiple functions: it redistributes ball contact areas to increase bonding area, provides thermal expansion buffering, and serves as a mechanical support structure. By consolidating these functions into a single component, the patent increases bonding area without proportionally increasing overall device complexity.
Solution Approach 2:
The patent transitions from two-dimensional chip-to-substrate bonding to three-dimensional stacked integration with the interposer. This dimensional change allows the bonding area to be distributed across multiple layers and locations, effectively increasing the total bonding area while managing complexity through vertical integration rather than horizontal expansion.
3Productivity
If multiple chips are incorporated in 3D package, then integration density is improved, but thermal expansion mismatch and warpage worsen
Solution Approach 1:
The patent carefully selects and adjusts the thermal expansion parameters of each layer in the 3D stacked structure. The interposer material is chosen to have a thermal expansion coefficient that creates a gradient, transitioning from the chip material to the substrate material. This gradual parameter change reduces overall thermal expansion mismatch, enabling multiple chips to be integrated in 3D without excessive warpage.
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 enhances the yield and reduces production costs by facilitating efficient 3D IC package formation, minimizing warpage, and optimizing thermal expansion compatibility.
Implementation Method 1
using dummy structures to overlay scribe lines and reduce thermal expansion mismatch
Implementation Method 2
forming encapsulants to minimize stress and warpage
Data Source
AI summary
A package structure including a bottom die, a first die, a second die, an encapsulant and a first dummy structure is provided. The first die and a second die are bonded to a first side of the bottom die. The encapsulant laterally encapsulates the first die and the second die. The first dummy structure is bonded to the first side of the bottom die, wherein a sidewall of the first dummy structure is coplanar with a first sidewall of the bottom die.