Laser Kerf Offset Mapping for Precise Wafer Dicing
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Solution Overview
Problem
Current semiconductor wafer dicing methods, such as scribing and sawing, result in chipping and cracking, leading to reduced die yield and wasted wafer real estate, while plasma dicing faces cost and implementation challenges, particularly with metals like copper.
Innovation Solution
A hybrid laser scribing and plasma etching process with offset correction mapping, using a sacrificial wafer to determine and apply accurate scribe line offsets, ensuring precise alignment and minimizing damage during die singulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional scribing or sawing methods are used for wafer dicing, then the dicing process can be completed, but chipping and cracking occur along the severed edges of the dice, reducing die yield and requiring additional spacing between dice
Solution Approach 1:
The patent replaces traditional mechanical dicing methods (diamond scribe or saw) with a laser-based system that uses optical energy to ablate material and create scribe lines. This substitution eliminates the mechanical contact that causes chipping and cracking, allowing scribe lines to be formed without damaging the dice edges.
Solution Approach 2:
The patent employs precise control of laser parameters (power, speed, pulse duration) to optimize the scribing process. By adjusting these parameters, the laser can create clean scribe lines with minimal thermal damage, preventing chipping and cracking while maintaining high die yield.
2Area of stationary object
If traditional scribing or sawing methods are used for wafer dicing, then the dicing process can be completed, but additional spacing must be maintained between dice to prevent damage, wasting wafer real estate
Solution Approach 1:
The laser-based scribing system eliminates the need for additional spacing between dice that is required when using mechanical methods. Since the laser creates scribe lines without physical contact, there is no risk of chipping or cracking that would extend into adjacent dice, allowing maximum utilization of wafer area.
3Productivity
If sawing is used for wafer dicing, then thicker wafers can be processed, but the blade thickness and required spacing reduce the number of dice per wafer
Solution Approach 1:
The laser scribing system replaces the physical saw blade with a focused beam of light, eliminating blade thickness entirely. This allows scribe lines to be formed with minimal width and no required spacing between dice, maximizing the number of dice that can be produced from each wafer.
4Object-affected harmful factors
If plasma dicing is used, then certain processing challenges may be avoided, but cost and implementation complexity increase significantly
Solution Approach 1:
The patent uses laser scribing as an intermediate step before plasma dicing, replacing the need for complex plasma-only processes. The laser pre-forms scribe lines that guide subsequent plasma etching, simplifying the overall process while maintaining compatibility with metal layers and avoiding the full complexity of direct plasma dicing.
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 enhances die density and wafer yield by accurately aligning scribe lines, reducing chipping and cracking, and optimizing the use of wafer space, while also addressing the limitations of traditional dicing methods.
Implementation Method 1
patterning the mask and the semiconductor wafer with a laser scribing process
Implementation Method 2
hybrid laser scribing and plasma dicing process
Data Source
AI summary
Embodiments of the present disclosure include methods of determining scribing offsets in a hybrid laser scribing and plasma dicing process. In an embodiment, the method comprises forming a mask above a semiconductor wafer. In an embodiment, the semiconductor wafer comprises a plurality of dies separated from each other by streets. In an embodiment, the method further comprises patterning the mask and the semiconductor wafer with a laser scribing process. In an embodiment, the patterning provides openings in the streets. In an embodiment, the method further comprises removing the mask, and measuring scribing offsets of the openings relative to the streets.