Semiconductor Package Window Structure for Warpage and Void Scanning
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Solution Overview
Problem
Semiconductor packages face challenges with warpage due to mechanical stress and the difficulty in detecting voids in hybrid bond layers, especially with the attenuation of high-frequency acoustic waves by metal-containing layers, which can lead to package failure.
Innovation Solution
Incorporating a 'window' or 'aquarium window' structure made of low-density material within the semiconductor package to relieve warpage stress and improve void detection by providing a path for acoustic waves that minimizes absorption and reflection, allowing for effective inspection using scanning acoustic microscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal-containing layers are used in semiconductor packages, then electrical functionality is improved, but high-frequency acoustic wave attenuation increases making void detection difficult
Solution Approach 1:
The package structure is segmented to include a dedicated inspection region with reduced metal content, allowing acoustic waves to pass through while maintaining metal-containing layers in functional regions for electrical performance
Solution Approach 2:
A low-density material layer is introduced as an intermediary between the acoustic wave source and the hybrid bond layer, reducing acoustic attenuation and enabling effective void detection
2Adaptability or versatility
If heterogeneous device dies are stacked vertically to form System on Integrated Chip, then device functionality and performance are improved, but mechanical stress and warpage increase
Solution Approach 1:
The package structure incorporates regions with different material properties - low-density material in inspection regions and metal-containing layers in functional regions - to simultaneously manage stress and enable detection
Solution Approach 2:
The package uses composite construction combining low-density materials and metal-containing layers in specific configurations to balance mechanical stress management with electrical functionality
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 window structure reduces warpage and enhances the detection of voids in hybrid bond layers, improving the reliability and performance of semiconductor packages by reducing mechanical stress and attenuating effects on acoustic waves.
Implementation Method 1
improve void detection by providing a path for acoustic waves that minimizes absorption and reflection
Implementation Method 2
minimizes absorption and reflection of acoustic waves
Implementation Method 3
relieve warpage stress
Data Source
AI summary
Methods for reducing warpage and increasing the effectiveness of hybrid bond void testing are disclosed. A semiconductor package has a first side and a second side, with a dummy bond pad located on the second side, and at least one metal-containing layer between the first side and the second side (for example a redistribution layer). A warpage control structure is provided in the semiconductor package that extends from the first side into the semiconductor package, and is aligned with the dummy bond pad. The warpage control structure is made of a low-density filling. This relieves stress that causes/increases warpage. When a hybrid bond is formed between the semiconductor package and another semiconductor package, the warpage control structure maximizes acoustic wave penetration for testing the quality of the hybrid bond at the dummy bond pad.