Multi-Layer Die Attach Film for Stacked Semiconductor Package
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Solution Overview
Problem
Semiconductor packages face challenges in minimizing size while preventing deformation of stacked chips, as the addition of support members or thick upper chips can increase package size.
Innovation Solution
A semiconductor package design utilizing multi-layer die attach films with varying binder components and protrusion portions to securely attach and support stacked chips, minimizing the package size by using a package base substrate, lower and upper chips, and bonding wires, where the first die attach film has a higher weight-average molecular weight binder component and the second die attach film has a lower weight-average molecular weight binder component, with protrusions covering side and top surfaces to enhance stability and reduce deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plurality of semiconductor chips are stacked, then the capacity and functionality of the semiconductor package are improved, but the package size increases due to the need for support members or thickened upper chips
Solution Approach 1:
The die attach film is segmented into multiple layers with different functions: a first layer for attaching the upper chip to the lower chip, and a second layer for preventing deformation by extending to cover side surfaces. This segmentation allows each layer to be optimized for its specific function, enabling chip stacking without requiring additional support members that would increase package size.
Solution Approach 2:
The second layer of the die attach film extends in the horizontal dimension to cover side surfaces of the lower chip, rather than only providing vertical attachment. This dimensional extension provides deformation prevention functionality within the existing package footprint, avoiding the need for additional vertical space that would increase package size.
2Reliability
If support members are added to prevent deformation of stacked chips, then the reliability is improved, but the device complexity and package size increase
Solution Approach 1:
The die attach film performs multiple functions: it attaches the upper chip to the lower chip and simultaneously prevents deformation of the stacked chips. By making the die attach film multi-functional, the patent eliminates the need for separate support members, thereby reducing device complexity while maintaining reliability.
Solution Approach 2:
The attachment function and deformation prevention function are merged into a single die attach film structure. The first layer provides attachment while the second layer provides deformation prevention, combining what would traditionally require separate components into one integrated solution, thus reducing device complexity.
3Reliability
If the upper chip is thickened to prevent deformation, then the reliability is improved, but the package size and weight increase
Solution Approach 1:
The second layer of the die attach film acts as an intermediary element between the upper and lower chips, providing deformation prevention without requiring the upper chip itself to be thickened. This intermediary layer absorbs the mechanical stress and prevents deformation while maintaining a thin profile, thus avoiding the volume increase that would result from thickening the upper chip.
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 design effectively prevents chip deformation and minimizes package size by providing robust attachment and support, allowing for efficient stacking of chips without the need for additional support members, thereby reducing the overall volume of the semiconductor package.
Implementation Method 1
a first die attach film (DAF) attached to a bottom surface of the upper chip to cover at least a portion of the lower chip
Implementation Method 2
Each of the first attaching layer and the second attaching layer may include a binder component, and a weight-average molecular weight of the binder component of the first attaching layer may be larger than a weight-average molecular weight of the binder component of the second attaching layer
Implementation Method 3
The second attaching layer may include a protrusion portion protruding out of a range occupied by the upper chip, in a space between a level of the bottom surface of the upper chip and a level of a top surface of the package base substrate
Data Source
AI summary
Provided is a semiconductor package that may prevent deformation of stacked semiconductor chips and minimize a semiconductor package size. The semiconductor package includes a package base substrate, a lower chip stacked on the package base substrate, an upper chip stacked on the lower chip, and a first die attach film (DAF) attached to a bottom surface of the upper chip to cover at least a portion of the lower chip. The first DAF may be a multi-layer film including a first attaching layer contacting the bottom surface of the upper chip and a second attaching layer attached to a bottom of the first attaching layer to cover at least a portion of a side surface of the lower chip.