Wafer Laser Dicing with Staggered Modified Layers
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Solution Overview
Problem
The existing methods for dividing wafers into individual device chips using laser processing often result in chipping at the corners where dicing lines intersect, leading to a reduction in chip quality due to rubbing and chipping of chip corners.
Innovation Solution
A method involving the formation of first and second modified layers along intersecting dicing lines, where the laser beam is undulated in a staggered pattern using spatial light modulators or similar devices to prevent straight formation of second modified layers, thereby preventing corner chipping during wafer division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser beam is applied along both first direction dicing lines and second direction dicing lines to form modified layers, then the wafer can be divided into individual device chips, but the corners of the device chips are liable to rub against each other and be chipped at intersection points
Solution Approach 1:
The patent applies curvature by undulating the laser beam in a staggered pattern along the dicing lines, transforming the straight laser path into a curved/wavy trajectory. This causes the modified layers to follow a staggered pattern rather than straight lines, preventing corner chipping during wafer division while maintaining efficient processing
2Ease of manufacture
If the focused spot of the laser beam is positioned inside the wafer along projected dicing lines to form modified layers, then the wafer can be divided into individual device chips, but corners of device chips are chipped at points where first and second modified layers extend across each other
Solution Approach 1:
The patent performs preliminary action by forming the modified layers with a staggered pattern before the actual wafer division occurs. By pre-positioning the modified layers in a staggered configuration rather than straight alignment, the corners of device chips are prevented from rubbing against each other during division, thereby maintaining chip quality while enabling easy manufacture
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 effectively prevents corner chipping during wafer division, maintaining the quality of device chips by ensuring that corners of the chips do not rub against each other at intersection points.
Implementation Method 1
applying a laser beam having a wavelength transmittable through the wafer to the wafer while positioning a focused spot of the laser beam inside the wafer along the projected dicing lines
Implementation Method 2
applying a laser beam having a wavelength transmittable through the wafer to the wafer while positioning a focused spot of the laser beam inside the wafer along the projected dicing lines, thereby forming first modified layers in the wafer
Data Source
AI summary
A method of processing a wafer to divide the wafer into individual device chips, includes a second modified layer forming step of applying a laser beam to the wafer while positioning a focused spot of the laser beam inside the wafer along the projected dicing lines extending in a second direction intersecting with a first direction, thereby forming second modified layers in the wafer along the projected dicing lines extending in the second direction. In the second modified layer forming step, when the focused spot of the laser beam along the projected dicing lines extending in the second direction reaches first modified layers, the focused spot of the laser beam is shifted along the first modified layers to thereby undulate the laser beam in a staggered pattern to prevent the second modified layers from being formed straight in the wafer along the projected dicing lines extending in the second direction.