Semiconductor Wafer Dicing with Rotating Laser Scribing and Plasma Etching
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Solution Overview
Problem
Current semiconductor wafer dicing methods, such as scribing and sawing, often result in chipping and cracking, leading to waste of wafer real estate and inefficiencies, while plasma dicing faces cost and implementation challenges, particularly with metals like copper.
Innovation Solution
A hybrid method involving a uniform rotating beam laser scribing process followed by plasma etching to singulate integrated circuits, which improves trench uniformity and reduces damage, enabling more efficient and cost-effective die separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scribing or sawing is used to dice the wafer, then the wafer can be separated into individual dice, but chipping and cracking occur along the severed edges
Solution Approach 1:
The patent replaces mechanical scribing and sawing systems with a laser-based system. The laser beam melts and vaporizes material along the street regions to create trenches, eliminating mechanical contact that causes chipping and cracking. This is achieved by focusing laser energy to selectively remove material without physical force application.
Solution Approach 2:
The patent changes the physical state and properties of materials through laser heating. The laser beam raises the temperature of the street regions to melting and vaporization points, transforming the material state from solid to liquid to gas, thereby creating clean separations without mechanical stress that causes edge damage.
2Reliability
If additional spacing is required between dice to prevent damage, then chipping and cracking are reduced, but wafer real estate is wasted
Solution Approach 1:
The laser-based dicing system creates precise trenches with controlled width and depth, allowing for minimal spacing between dice. The laser can accurately define the separation path without the blade width constraints of mechanical sawing, maximizing the usable wafer area while maintaining dice integrity.
3Productivity
If sawing is used to dice the wafer, then thick wafers can be separated, but substantial cleaning is required to remove particles and contaminants
Solution Approach 1:
The laser ablation process vaporizes material directly from the wafer, eliminating the generation of particulate contaminants that occur with mechanical sawing. The melted and vaporized material is removed by gas flow, leaving a clean surface that requires minimal post-processing cleaning operations.
4Adaptability or versatility
If plasma dicing is implemented, then alternative dicing method is provided, but cost and throughput limitations arise
Solution Approach 1:
The patent employs a laser system that can process various wafer materials and thicknesses without the material-specific constraints of plasma dicing. The laser parameters can be adjusted to handle different materials including metals like copper, providing versatility without the throughput limitations and high implementation costs of plasma processing systems.
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 minimizes chipping and cracking, enhances product quality, and increases the number of dice that can be produced from a standard wafer, while reducing post-processing cleaning needs and operational costs.
Implementation Method 1
The laser beam is focused on the streets to melt and vaporize the material along the streets to form trenches
Implementation Method 2
The laser beam is focused on the streets to melt and vaporize the material along the streets
Implementation Method 3
The laser beam is focused on the streets to melt and vaporize the material along the streets
Implementation Method 4
The semiconductor wafer is then plasma etched through the gaps in the patterned mask to singulate the integrated circuits
Data Source
Figure 1
Figure 2A~2C
Figure 3~4
AI summary
Methods of dicing semiconductor wafers, each wafer having a plurality of integrated circuits, are described. In an example, a method of dicing a semiconductor wafer having a plurality of integrated circuits involves forming a mask above the semiconductor wafer, the mask composed of a layer covering and protecting the integrated circuits. The mask is then patterned with a uniform rotating laser beam laser scribing process to provide a patterned mask with gaps, exposing regions of the semiconductor wafer between the integrated circuits. The semiconductor wafer is then plasma etched through the gaps in the patterned mask to singulate the integrated circuits.