Side Molding for Semiconductor Wafer Sawing
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Solution Overview
Problem
Wafer-level chip scale packages face issues with side wall cracks during the sawing process due to direct contact with sawing tools and inadequate handling of molding materials, leading to manufacturing inefficiencies and reliability concerns.
Innovation Solution
A method involving forming sawing grooves on a wafer, filling them with a molding material, and using a backgrinding process to thin the wafer, followed by secondary sawing of the molding material to minimize direct contact with the sawing tool, thereby preventing side wall cracks and improving handling during chip division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer is directly sawn into individual chips using conventional sawing tools, then the chip division process is simple and fast, but side wall cracks occur in the chips due to direct contact with the sawing tool
Solution Approach 1:
A dicing sled is introduced as an intermediary carrier between the wafer and the sawing tool. The wafer is mounted on the dicing sled, which supports the wafer during the sawing process. This intermediary structure distributes the mechanical stress and prevents direct contact between the sawing blade and the wafer edges, thereby preventing side wall cracks while maintaining efficient chip division
Solution Approach 2:
The wafer is preliminarily prepared by mounting it onto the dicing sled before the sawing process. This preliminary action ensures proper positioning and support of the wafer, allowing the sawing tool to cut through the wafer cleanly without causing side wall cracks. The dicing sled is pre-configured with appropriate support structures to accommodate the wafer thickness and geometry
2Reliability
If molding material is applied to cover the entire wafer surface for protection, then handling and protection are improved, but it becomes difficult to precisely fill only the sawing grooves and increases material consumption
Solution Approach 1:
Instead of applying molding material uniformly across the entire wafer surface, the method applies molding material selectively and locally only to the sawing grooves. This local quality approach ensures that the molding material fills the grooves precisely to provide protection and support during sawing, while avoiding unnecessary material application on other wafer regions, thus improving both precision and material efficiency
Solution Approach 2:
The method extracts the molding material application from a full-surface process and concentrates it specifically on the sawing grooves. By taking out only the necessary regions (the grooves) for molding material application, the process achieves precise filling while reducing overall material consumption and simplifying the application process
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
This approach reduces the occurrence of side wall cracks and enhances the reliability and efficiency of the semiconductor package manufacturing process by minimizing direct contact between the wafer and the sawing tool, allowing for continuous handling and reducing manufacturing costs.
Implementation Method 1
filling the sawing grooves with a molding material
Implementation Method 2
filling the sawing grooves with a molding material
Implementation Method 3
thinning the wafer based on a backgrinding process
Implementation Method 4
bonding solder balls onto the UBM pattern
Data Source
AI summary
Provided is a method of manufacturing a semiconductor package, the method including forming sawing grooves by sawing a wafer along individual chip boundaries in a downward direction from a top surface of the wafer by a thickness less than a wafer thickness, filling the sawing grooves with a molding material, forming a redistribution pattern, a passivation pattern, and an under bump metal (UBM) pattern on the wafer, bonding solder balls onto the UBM pattern, thinning the wafer based on a backgrinding process, and dividing the wafer into individual chips by sawing the molding material filled in the sawing grooves, in a downward direction.