Semiconductor Package Warpage Release Layer for CTE Mismatch
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Solution Overview
Problem
The challenge in forming reliable chip packages arises from the decreasing feature sizes of semiconductor dies and package components, leading to issues with warpage and mismatch in thermal expansion coefficients (CTE) during packaging processes.
Innovation Solution
A warpage release layer structure is introduced, comprising organic material layers and high CTE material layers, which are aligned with the semiconductor dies to mitigate CTE mismatch and reduce warpage, thereby improving package reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes of semiconductor dies and package components are decreased to increase integration density, then productivity and device miniaturization are improved, but warpage control and manufacturing reliability deteriorate due to CTE mismatch
Solution Approach 1:
The patent introduces an intermediary layer structure between the semiconductor die and package substrate that acts as a buffer to absorb CTE mismatch. This intermediary structure includes multiple layers with different material properties that gradually transition the thermal expansion characteristics, preventing direct stress transmission and warpage formation while maintaining miniaturized feature sizes.
Solution Approach 2:
The patent employs composite material structures in the package components and interposer substrates, combining materials with different CTE values in a layered configuration. This composite approach allows the structure to accommodate thermal expansion differences through controlled deformation of individual layers, maintaining overall package reliability despite reduced feature sizes.
2Ease of manufacture
If conventional packaging processes are used without warpage release layers, then manufacturing simplicity is maintained, but warpage occurs during flux-dipping and flip-chip bonding due to CTE mismatch
Solution Approach 1:
The patent applies warpage release layers and stress compensation structures during the packaging process before the final bonding operations. These preliminary structures pre-compensate for the thermal stresses that will occur during flux-dipping and flip-chip bonding, allowing conventional manufacturing processes to proceed without causing warpage issues.
3Reliability
If warpage release layer structure is added to address CTE mismatch, then package reliability and warpage control are improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent modifies material parameters such as CTE, thickness, and elastic modulus of the warpage release layers to achieve optimal warpage compensation. By carefully selecting and tuning these parameters, the structure provides reliable warpage control with minimal additional complexity, as the same layer structure serves multiple functions including stress management and mechanical support.
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
The warpage release layer structure effectively controls and reduces package warpage, enhancing device yield and performance by addressing CTE mismatch issues during flux-dipping and flip-chip bonding processes.
Implementation Method 1
A warpage release layer structure is formed over the interposer substrate and includes a high CTE material layer formed over the organic material layer. The high CTE material layer has a CTE that is substantially equal to or greater than 9 ppm/° C. The formed stress in the package at high temperature and the formed stress in the package at room temperature due to the CTE mismatch between the semiconductor die and the interposer substrate are mitigated by the use of the high CTE material layer formed over the semiconductor die
Data Source
AI summary
A chip package structure is provided. The chip package structure includes a molding compound layer on an interposer substrate. The chip package structure also includes a first semiconductor die over the interposer substrate and surrounded by the molding compound layer. The chip package structure further includes a warpage release layer structure. The warpage release layer structure includes a first organic material layer on the first semiconductor die and the molding compound layer. The warpage release layer structure also includes a first metal layer over the first organic material layer. The first metal layer exposes a portion of a top surface of the first organic material layer.