Wafer Dicing Using Dome-Shaped Chuck and Perforations
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Solution Overview
Problem
Conventional wafer dicing methods often fail to separate every die due to reliance on lateral forces, resulting in a high rate of unseparated dies, typically around 500 defect parts per million (DPPM).
Innovation Solution
The stealth dicing technique involves adhering a wafer with perforations to a dicing tape on a flex frame, which is moved from a flat position to a position over a dome-shaped chuck, inducing transverse forces that cause the perforations to break, ensuring precise separation of dies. This method uses laser processing to create polycrystalline perforations in a monocrystalline wafer structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lateral force dicing is used, then the dicing process is simple, but the separation completeness is poor with high defect rate
Solution Approach 1:
The patent introduces a dome-shaped chuck that applies transverse forces through a curved surface, causing the dicing tape to deform and apply breaking forces to the perforations. This curvature-based approach transforms the force application mechanism from simple lateral pushing to a more effective transverse breaking action, achieving complete die separation with less than 5 DPPM defect rate.
Solution Approach 2:
The patent transitions from applying forces only in the lateral direction (parallel to wafer surface) to applying transverse forces (perpendicular to the flat surface of the dicing tape) through the dome-shaped chuck. This dimensional change in force application enables effective perforation breaking and complete die separation.
2Manufacturing precision
If laser processing is used to create polycrystalline perforations, then the perforation structure is optimized for breaking, but the manufacturing complexity increases
Solution Approach 1:
The patent performs laser scribing to create polycrystalline perforations in advance, before the dicing process. This preliminary action prepares the wafer with pre-formed weak planes that will break cleanly when transverse forces are applied during dicing, ensuring precise die separation while using established laser processing technology.
Solution Approach 2:
The patent changes the structural parameter of the perforations by creating polycrystalline regions through laser processing in the monocrystalline wafer. This parameter change creates a distinct structural difference between the perforation material and the wafer material, enabling the perforations to break at controlled locations when transverse forces are applied.
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 significantly reduces the number of unseparated dies, lowering the defect rate from 500 DPPM to less than 5 DPPM by applying non-uniform lateral forces across the wafer thickness, ensuring effective separation and packaging of IC chips.
Implementation Method 1
applying a downward force on a periphery of the dicing tape. The downward force causes a bottom surface of the dicing tape to deform around a contour of a dome-shaped chuck, breaking the perforations in the wafer
Implementation Method 2
The dome-shaped chuck induces forces transverse to the flat surface of the dicing tape that cause the plurality of perforations in the wafer to break
Implementation Method 3
The wafer has a monocrystailine structure and the perforations have a polycrystalline structure. This method uses laser processing to create polycrystalline perforations in a monocrystalline wafer structure
Data Source
AI summary
A method for dicing a wafer includes scribing perforations in a wafer. The wafer has a monocrystalline structure and the perforations have a polycrystalline structures The method also includes adhering the wafer to a top surface of a dicing tape and applying a downward force on a periphery of the dicing tape. The downward force causes a bottom surface of the dicing tape to deform around a contour of a dome shaped chuck, breaking the perforations in the wafer.