Semiconductor Package Buffer Layer Stress Management
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Solution Overview
Problem
Stacked semiconductor packages face issues with internal stress during production, leading to warping and reduced long-term reliability due to mismatched coefficients of linear thermal expansion between materials, and delamination of layers with different properties.
Innovation Solution
A semiconductor package design incorporating an intermediate buffer layer with a lower elastic modulus than the encapsulation materials, positioned between the semiconductor devices and lines, to alleviate internal stress and prevent delamination, while also using different insulating materials for the first and second encapsulation layers to manage stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large metal substrate is used to support multiple semiconductor devices, then mass productivity is improved, but the substrate warps during the production process due to internal stress
Solution Approach 1:
An intermediate buffer layer is introduced between the first and second encapsulation materials. This buffer layer acts as a mediator to release internal stress generated during the curing process, preventing warp of the entire stacked semiconductor package while maintaining the large substrate structure for mass productivity
Solution Approach 2:
The elastic modulus of the intermediate buffer layer is specifically designed to be lower than that of the encapsulation materials. This parameter change allows the buffer layer to effectively absorb and release internal stress, preventing substrate warping during production
2Reliability
If resin layers are cured to insulate semiconductor devices, then electrical insulation is achieved, but internal stress causes warping and delamination
Solution Approach 1:
The intermediate buffer layer serves as a stress-release layer between encapsulation materials with different insulating properties. It mediates the internal stress generated during curing, preventing both warping and delamination while maintaining the electrical insulation function of the resin layers
Solution Approach 2:
The patent uses different insulating materials for the first and second encapsulation materials, with an intermediate buffer layer having different elastic properties. This composite structure allows each layer to perform its specific function - insulation and stress management - simultaneously
3Adaptability or versatility
If materials with different coefficients of linear thermal expansion are used, then functional requirements are met, but thermal expansion mismatch causes warping
Solution Approach 1:
The intermediate buffer layer acts as a compensatory layer between materials with different thermal expansion coefficients. It absorbs the dimensional changes caused by thermal expansion mismatch, preventing warping while allowing the use of functionally appropriate materials
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 enhances the reliability and flexibility of semiconductor packages by reducing internal stress, preventing warping, and improving long-term reliability by matching thermal expansion coefficients and maintaining structural integrity.
Implementation Method 1
an intermediate buffer layer which releases the internal stress, with an insulating layer formed of a material having an elastic modulus lower than that of the encapsulation materials
Implementation Method 2
a material of the support substrate, a resin material, silicon and a metal material used for lines used for the semiconductor package have coefficients of linear thermal expansion thereof not matched, and this causes the warp
Data Source
AI summary
A semiconductor package includes a first semiconductor device provided on a support substrate; a first encapsulation material covering the first semiconductor device; a first line provided on the first encapsulation material, the first line being connected with the first semiconductor device; an intermediate buffer layer covering the first line, and a second encapsulation material provided on the intermediate buffer layer. The first encapsulation material and the second encapsulation material are each formed of an insulating material different from an insulating material used to form the intermediate buffer layer. A second semiconductor device covered with the second encapsulation material may be provided on the intermediate buffer layer.