Laser Wafer Dicing Marks to Prevent Cracks at Line Intersections
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Solution Overview
Problem
The quality of device chips is lowered due to the generation of cracks in unintended directions at the intersection of planned dividing lines during laser processing of wafers, especially when the crystal orientation deviates from the planned dividing lines.
Innovation Solution
A laser processing method that involves forming first and second processing marks in non-orthogonal directions at the intersection of planned dividing lines, with an unprocessed region remaining at the intersection, and subsequently processing this unprocessed region to form coupling processing marks that connect the first and second processing marks, thereby preventing radial crack generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser processing is executed along planned dividing lines to form dividing grooves, then the wafer can be divided into individual device chips, but cracks of approximately several tens of micrometers are radially generated at the intersection of orthogonal dividing lines, lowering the quality of device chips
Solution Approach 1:
The laser processing is divided into three segments: first processing marks along the first direction, second processing marks along the second direction, and coupling processing marks at intersections. This segmentation allows each part to serve a specific function - the first and second marks create dividing grooves while the coupling marks prevent radial crack generation at intersections without compromising device chip quality
Solution Approach 2:
The first and second processing marks are formed in advance before the coupling processing marks. By preliminarily creating the dividing grooves along orthogonal directions and then adding coupling marks at intersections, the method prevents radial cracks from forming during the final coupling processing stage, thereby maintaining device chip quality while ensuring complete wafer division
2Manufacturing precision
If the crystal orientation of the wafer is considered for accurate dividing, then the quality of device chips can be maintained, but the processing time and complexity increase due to the need for additional processing steps at intersections
Solution Approach 1:
Different processing approaches are applied to different locations on the wafer. Along the dividing lines, standard laser processing creates dividing grooves, while at the intersections, coupling processing marks are formed with specific orientation relative to the crystal structure. This local differentiation ensures accurate dividing that accounts for crystal orientation without requiring complex processing throughout the entire wafer
Solution Approach 2:
The processing approach transitions from two-dimensional orthogonal marking to three-dimensional coupling marking at intersections. By forming coupling processing marks that connect the first and second processing marks in a third dimensional aspect, the method accurately accounts for crystal orientation at intersections while maintaining overall processing efficiency and avoiding excessive complexity
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 method effectively prevents the generation of radial cracks at the intersection of planned dividing lines, thereby maintaining the quality of device chips formed from the processed wafers.
Implementation Method 1
a first processing step of forming a first processing mark by executing processing to form an origin of dividing or a dividing groove through executing irradiation with the laser beam
Implementation Method 2
a first processing step of forming a first processing mark by executing processing to form an origin of dividing or a dividing groove through executing irradiation with the laser beam
Implementation Method 3
a type that executes irradiation with the focal point of a laser beam with a wavelength having absorbability with respect to a wafer along a planned dividing line of the wafer to form a groove by ablation processing
Data Source
AI summary
A laser processing method includes forming a first processing mark to form an origin of dividing or a dividing groove with a laser beam in a first direction, and forming a second processing mark by forming an origin of dividing or a dividing groove with the laser beam in a second direction that intersects the first direction. An unprocessed region in which the processing is not executed remains at an intersection at which the first direction and the second direction intersect each other. The method further includes processing the unprocessed region. The unprocessed region processing step forms a coupling processing mark that couples the first processing mark and the second processing mark to each other to form an origin of dividing or a dividing groove with the laser beam in a direction arising from setting an inclination with respect to the first direction or the second direction.