Hybrid Wafer Dicing with Rectangular Laser Scribing and Plasma Etch
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Solution Overview
Problem
Current methods for dicing semiconductor wafers, such as scribing and sawing, result in chipping and cracking, leading to waste of wafer real estate and increased spacing requirements, while plasma dicing faces cost and implementation challenges, particularly with metals like copper.
Innovation Solution
A hybrid method involving rectangular laser spot-based laser scribing followed by plasma etching to singulate integrated circuits, reducing stress concentration and eliminating sharp corners, thereby minimizing damage and improving edge quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scribing or sawing is used to dice semiconductor wafers, 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 processes with a hybrid laser scribing and plasma etching process. The laser scribes the wafer along predetermined streets without mechanical contact, and plasma etching removes the material between dice, eliminating the chipping and cracking caused by mechanical forces while maintaining high productivity
Solution Approach 2:
The patent changes the physical state and parameters of the processing method by using laser energy for scribing and plasma for etching, transitioning from mechanical to non-mechanical processes. This parameter change enables clean separation without the harmful effects of mechanical stress
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:
By replacing mechanical scribing with laser scribing followed by plasma etching, the patent achieves clean cuts without chipping or cracking, allowing dice to be placed closer together and maximizing the usable wafer area while maintaining reliability
3Productivity
If sawing is used to dice thicker wafers, then separation is achieved, but substantial cleaning is required to remove particles and contaminants
Solution Approach 1:
The patent replaces mechanical sawing with laser scribing and plasma etching, which produce minimal debris and contaminants. The plasma process inherently cleans the surfaces during etching, significantly reducing or eliminating the need for subsequent cleaning steps while maintaining the ability to dice thick wafers
4Adaptability or versatility
If plasma dicing is implemented, then alternative dicing capability is provided, but cost increases due to lithography operations
Solution Approach 1:
The patent segments the plasma process into a selective etching step that follows laser scribing, rather than requiring complete lithographic patterning. This segmentation allows plasma to be used for the final separation step without the full cost burden of lithography, reducing implementation cost while maintaining versatility
Solution Approach 2:
The patent uses plasma etching partially, only for the final separation step after laser has done the bulk of the work, rather than using plasma for the entire dicing process. This partial application reduces cost while maintaining the benefits of plasma etching for clean separation
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 stress concentration, enhances die edge quality, increases die density, and decreases equipment costs by allowing for closer spacing of integrated circuits without chipping or cracking, thus optimizing wafer usage.
Implementation Method 1
The mask is then patterned with a rectangular laser spot-based laser scribing process to provide a patterned mask with gaps, exposing regions of the semiconductor wafer between the integrated circuits
Implementation Method 2
The semiconductor wafer is then plasma etched through the gaps in the patterned mask to singulate the integrated circuits
Data Source
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 rectangular laser spot-based 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.