Wafer Singulation with Plasma Etch and Vibration
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Solution Overview
Problem
The semiconductor industry faces challenges in singulating die from a wafer due to non-compatibility of plasma dicing with wafer backside layers, which hinders subsequent processing and reduces manufacturing throughput.
Innovation Solution
A method and apparatus for singulating die using a plasma etch process that selectively etches through the wafer to form narrow singulation lines, combined with a whole wafer compression system applying controlled pressure and mechanical vibrations to separate backside layers within the singulation lines, allowing for batch separation and minimizing damage to the die.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma dicing is used to singulate die, then throughput is increased and scribe line width is reduced, but backside layers cannot be effectively removed or separated
Solution Approach 1:
The patent divides the singulation process into two distinct stages: first, plasma dicing creates narrow scribe lines to separate die with high throughput; second, a separate mechanical compression process with vibrations specifically targets and removes backside layers within the scribe lines. This segmentation allows each process to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent introduces an intermediary mechanical compression process with vibrations that acts as a mediator between the plasma dicing step and the final die separation. This intermediary step specifically addresses the backside layer removal problem that plasma dicing alone cannot solve, enabling both high throughput and effective layer separation.
2Reliability
If traditional scribing with diamond cutting wheel is used, then backside layers can be removed, but scribe grid width must be large and processing time exceeds one hour
Solution Approach 1:
The patent replaces the traditional mechanical diamond cutting wheel scribing process with a plasma-based etching system for creating scribe lines, followed by a vibration-assisted mechanical compression process for backside layer removal. This substitution dramatically reduces processing time from over one hour to a much shorter duration while maintaining effective backside layer separation.
Solution Approach 2:
The patent employs periodic mechanical vibrations during the compression process to facilitate backside layer separation. These periodic vibrations, applied through a vibration table or transducer, create cyclical stress that helps break and remove the backside layers within the scribe lines efficiently, reducing overall processing time compared to continuous static compression.
3Manufacturing precision
If plasma dicing is used, then narrow scribe lines are formed, but subsequent processing such as pick-and-place is hindered by remaining backside layers
Solution Approach 1:
The patent extracts and removes the problematic backside layers from within the narrow scribe lines created by plasma dicing. By applying mechanical compression with vibrations specifically targeted at the scribe line regions, the backside layers are pulled out and separated, leaving clean narrow scribe lines that do not interfere with subsequent pick-and-place and assembly processes.
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 enables efficient and cost-effective separation of backside layers, improving manufacturing throughput and facilitating subsequent processing steps like pick-and-place, while maintaining the integrity of the semiconductor die.
Implementation Method 1
A method and apparatus for singulating die using a plasma etch process that selectively etches through the wafer to form narrow singulation lines
Implementation Method 2
combined with a whole wafer compression system applying controlled pressure and mechanical vibrations to separate backside layers within the singulation lines
Implementation Method 3
applying controlled pressure and mechanical vibrations to separate backside layers within the singulation lines
Data Source
AI summary
A method of singulating a wafer includes providing a wafer having a plurality of die formed as part of the wafer and separated from each other by spaces. The wafer has first and second opposing major surfaces, a layer of material atop the second major surface, and portions of the layer of material are adapted to remain atop surfaces of the plurality of die after completion of the method of singulating the wafer. The method includes placing the wafer onto a carrier substrate and singulating the wafer through the spaces to form singulation lines, wherein singulating comprises leaving at least a portion of the layer of material under the singulation lines. The method includes separating the layer of material under the singulation lines by applying pressure to the wafer and applying high frequency vibrations to fatigue the layer of material.