Wafer Dice Laser Marking via Line Scan Camera
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Solution Overview
Problem
Conventional methods for marking wafer dies after the dicing process face challenges such as damage to the wafer or inaccurate positioning, and vision cameras require excessive time for individual measurement of each die.
Innovation Solution
Utilizing a line scan camera to quickly collect the shape and position information of irregularly arranged wafer dies, aligning its coordinate system with a laser marker for precise laser marking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vision camera is used to photograph each wafer die individually to measure position, then position information can be obtained, but the measuring process takes excessively long time
Solution Approach 1:
The patent divides the measurement process into multiple scanning passes, where a line scan camera captures position information of multiple wafer dies simultaneously in each pass. The wafer is scanned in segments across multiple passes to cover all dies, replacing the conventional method of photographing each die individually. This segmentation approach maintains measurement precision while dramatically reducing total measuring time.
Solution Approach 2:
The patent merges multiple measurement functions into a single line scan camera system that captures position information of multiple wafer dies simultaneously in one scan pass. By combining the measurement of multiple dies into a single operation, the system achieves the same measurement precision as individual photography but reduces time consumption proportionally to the number of dies measured in parallel.
2Manufacturing precision
If the conventional two-reference-die method is used for marking, then marking positions can be identified, but it becomes difficult to mark accurately when wafer dies are divided and located askew
Solution Approach 1:
The patent replaces the mechanical reference-die-based positioning system with an optical line scan camera system that automatically detects wafer die positions. Instead of relying on physical reference dies and mechanical coordinate systems, the system uses optical scanning to identify actual wafer die locations and orientations, then calculates appropriate marking positions. This substitution enables the system to adapt to divided wafer configurations where dies are located askew, while maintaining marking position accuracy.
Solution Approach 2:
The patent changes the coordinate system parameters and positioning methodology to accommodate divided wafer configurations. Rather than using a fixed two-reference-die coordinate system, the system dynamically determines positioning parameters based on actual wafer die positions detected by the line scan camera. This includes calculating adjusted marking positions that account for wafer die orientation and location variations, thereby maintaining manufacturing precision across different wafer configurations.
3Manufacturing precision
If wafer backgrinding is performed before dicing, then wafer thickness can be controlled, but fragments or chippings are generated from the back surface
Solution Approach 1:
The patent applies preliminary protective action by positioning the line scan camera and laser marking system to operate on the front surface of the wafer before dicing occurs. By performing marking operations on intact wafers with controlled thickness (achieved through conventional backgrinding), the system avoids generating fragments or chippings that would occur if marking were attempted after dicing when dies are already separated and askew. The preliminary marking preserves wafer integrity while achieving the desired function.
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
Enables accurate and efficient laser marking of wafer dies by rapidly collecting and utilizing position information, ensuring markings are placed correctly on each die.
Implementation Method 1
the line scan camera photographs each wafer die and then, through thus-captured images, the outline of each of the divided wafer dies is expressed
Implementation Method 2
a marking process for the thus-divided wafer dies is performed with a laser
Data Source
AI summary
Disclosed is a method for marking, by using a laser marker, a plurality of wafer dice divided by a wafer dicing process. The disclosed marking method for wafer dice comprises the steps of: setting a plurality of scan regions having a mutually overlapping portion on a wafer including the wafer dice; scanning the scan regions of the wafer a plurality of times by using a line scan camera; collecting position information of each of wafer dice located in regions in which the scan regions do not overlap; collecting, through image synthesis, position information of each of wafer dice located in regions in which the scan regions overlap; and marking, by using the laser marker, each of all the wafer dice of which the position information has been collected.