Semiconductor Package Surface-Modifying Film for Thermal Stress Reduction
Solution Overview
Problem
Semiconductor package structures face reliability issues due to thermal stress-induced tensile stress concentration caused by coefficient of thermal expansion (CTE) mismatch between components, leading to potential crack formation and circuit failure.
Innovation Solution
A manufacturing method involving a carrier with a debond layer and a buffer layer, where semiconductor dies are encapsulated with an insulating encapsulation and a surface-modifying material is applied, followed by a thermal treatment to form a surface-modifying film that enhances adhesion and reduces stress between the encapsulation and redistribution circuit structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semiconductor devices are packaged with other semiconductor devices or dies at the wafer level, then manufacturing efficiency is improved, but thermal stress-induced tensile stress concentration occurs due to CTE mismatch between components
Solution Approach 1:
A buffer layer is introduced as an intermediary between the carrier and the semiconductor wafer/dies. This buffer layer has a coefficient of thermal expansion (CTE) that is lower than the carrier but higher than the semiconductor components, creating a gradient that reduces thermal stress concentration. The buffer layer acts as a stress-absorbing intermediary that prevents direct transmission of thermal expansion forces from the carrier to the sensitive semiconductor components during temperature cycling.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the interface between components by applying a surface-modifying material to the carrier surface. This material changes the surface energy, roughness, and adhesion properties of the carrier, thereby improving the bonding strength between the carrier and the semiconductor wafer/dies. The parameter changes in surface properties reduce the likelihood of delamination under thermal stress while maintaining manufacturing efficiency.
2Adaptability or versatility
If redistribution circuit structures and encapsulants are formed, then circuit integration is improved, but crack or break occurs at the interface under thermal stress
Solution Approach 1:
A surface-modifying material is applied as an intermediary layer between the carrier and the redistribution circuit structure/encapsulant interface. This material serves as a stress-distributing mediator that prevents stress concentration at the vulnerable interface. The surface-modifying material has intermediate mechanical properties that bridge the stiffness mismatch between the rigid carrier and the more compliant encapsulant, thereby preventing crack initiation and propagation while allowing complex circuit integration.
3Adaptability or versatility
If dies are diced and integrated to a semiconductor substrate, then device functionality is improved, but warpage and circuit failure occur due to CTE mismatch
Solution Approach 1:
The patent changes the physical parameters of the substrate and interface layers to accommodate thermal expansion differences. By modifying the substrate thickness, material composition, and surface properties, the system can absorb thermal stress without developing excessive warpage. These parameter changes allow the integrated device structure to maintain structural stability and planarity across a range of operating temperatures while preserving full device functionality.
Solution Approach 2:
The patent explicitly addresses thermal expansion by selecting materials with appropriate coefficients of thermal expansion (CTE) for each layer in the stacked structure. The buffer layer and surface-modifying material are chosen with intermediate CTE values that create a gradient, allowing each layer to expand and contract at different rates without generating excessive stress. This controlled differential thermal expansion prevents warpage and maintains structural integrity during temperature cycling while enabling complex device integration.
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 method effectively reduces thermal stress and improves the reliability of semiconductor package structures by enhancing adhesion and preventing delamination, thereby ensuring the integrity of the redistribution circuit structure and encapsulation.
Implementation Method 1
a thermal treatment to form a surface-modifying film that enhances adhesion and reduces stress between the encapsulation and redistribution circuit structures
Implementation Method 2
heat causes components of the package to expand at their respective coefficients of thermal expansion (CTE) during operation. It is tensile stress concentration that develops due to the CTE mismatch between the components
Data Source
AI summary
A package structure includes a semiconductor die, an insulating encapsulation, a first redistribution circuit structure and a surface-modifying film. The semiconductor die has conductive terminals. The insulating encapsulation laterally encapsulates the semiconductor die and exposes the conductive terminals. The first redistribution circuit structure is located over the insulating encapsulation and electrically connected to the semiconductor die. The surface-modifying film is located on the insulating encapsulation and has a plurality of openings exposing edges of the conductive terminals, wherein the surface-modifying film separates the first redistribution circuit structure from the insulating encapsulation.