Wafer Dicing Groove Geometry for Crack Prevention
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Solution Overview
Problem
The existing dicing before grinding (DBG) method for semiconductor wafers results in groove bottoms becoming thinner and cracking during grinding, leading to fragments dropping and potential device defects.
Innovation Solution
A manufacturing method that forms cut grooves with varying groove bottom positions in the thickness direction, using a cutting blade with a gradually reduced thickness towards the tip, and grinding from the tip of the groove bottom to prevent fragment dropping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the back surface side of the wafer is gradually ground to thin the workpiece to finish thickness, then the wafer is divided into individual chips, but the groove bottoms become thinner and cracked during grinding, causing fragments to drop
Solution Approach 1:
The cut grooves are formed in advance with varying depths before grinding begins. By pre-forming grooves where the groove bottom position in the thickness direction varies, the structure is prepared beforehand to prevent cracking during the subsequent grinding process, eliminating the need for rear surface relief processing.
Solution Approach 2:
The cut grooves are formed with non-uniform depth characteristics, where the groove bottom position in the thickness direction varies across different locations. This local variation in groove depth creates areas of different thickness that prevent stress concentration and cracking during grinding, while maintaining the overall finish thickness requirement.
2Ease of manufacture
If uniform depth cut grooves are formed, then the cutting process is simple, but the groove bottoms crack during grinding due to thinning
Solution Approach 1:
Instead of forming uniform depth grooves, the invention forms cut grooves with varying depths where the groove bottom position in the thickness direction varies. This local variation in groove characteristics prevents cracking during grinding while still using a straightforward cutting process to create the non-uniform groove pattern.
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 method effectively prevents fragments from dropping during grinding, ensuring device integrity and reducing the risk of defects.
Implementation Method 1
a cutting step of cutting one surface of the workpiece by a cutting blade to thereby form cut grooves along the streets
Implementation Method 2
a grinding step of grinding another surface on a side opposite to the one surface of the workpiece to thereby thin the workpiece to a finish thickness of reaching the cut grooves
Data Source
AI summary
A chip manufacturing method for manufacturing a plurality of chips by dividing a workpiece with a plurality of intersecting streets set thereon includes a cutting step of cutting a front surface of the workpiece by a cutting blade to thereby form cut grooves along the streets, and then a grinding step of grinding a back surface on the side opposite to the front surface of the workpiece to thereby thin the workpiece to a finish thickness of reaching the cut grooves and to divide the workpiece into the plurality of chips. The cut grooves are formed such that the position of the groove bottom in the thickness direction of the workpiece varies in the width direction of the cut groove, and, in the grinding step, grinding is started from that tip of the groove bottom of the cut groove which is remote from the front surface of the workpiece.