Wafer Laser Dicing with Shield Tunnels for Precise Chip Separation
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Solution Overview
Problem
Existing methods for dividing wafers into individual device chips using high-power laser beams face challenges in accurately controlling the division lines, often resulting in chippings or fragments at the wafer's outer circumference, which can lower the quality of device chips.
Innovation Solution
A method involving two laser processing steps: the first forms shield tunnels with a modified layer in the wafer, and the second forms additional modified layers at closer intervals, inducing cracks along the projected dicing lines, allowing for precise division with reduced external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high-power laser beam is applied to form modified layers in hard wafers, then the modified layers can be formed effectively, but large external forces are required for division and chippings occur at the outer circumference
Solution Approach 1:
The patent segments the laser processing into two distinct steps: first forming shield tunnels with a first laser beam, then forming additional modified layers with a second laser beam at closer intervals. This segmentation allows the division process to be more controlled and reduces the need for large external forces, thereby preventing chippings at the outer circumference while maintaining division line accuracy.
Solution Approach 2:
The patent performs preliminary action by first forming shield tunnels along the projected dicing lines before applying the second laser beam. These shield tunnels act as pre-prepared channels that guide the subsequent modified layer formation and crack development, ensuring accurate division lines without requiring excessive external force that would cause chippings.
2Manufacturing precision
If high-power laser beam is used to form modified layers, then division can be achieved, but it is difficult to accurately control the division lines
Solution Approach 1:
The laser processing is divided into two sequential steps with distinct functions: the first step forms shield tunnels at larger intervals, while the second step forms additional modified layers at closer intervals. This segmentation improves division line control by separating the tunnel formation function from the modified layer formation function, reducing processing complexity despite using high-power lasers.
Solution Approach 2:
The shield tunnels formed in the first step serve as an intermediary structure that facilitates the second laser processing step. These tunnels act as guides and mediators that help control the formation of modified layers and subsequent cracks, thereby improving division line accuracy without excessively increasing overall processing complexity.
3Productivity
If large external forces are applied to divide the wafer, then division can be achieved, but chippings and fragments are produced at the outer circumference
Solution Approach 1:
The patent replaces the reliance on large mechanical external forces with a laser-based approach. By forming shield tunnels and additional modified layers through laser processing, the wafer creates internal cracks that enable division with minimal external force, thereby maintaining chip quality without sacrificing division efficiency.
Solution Approach 2:
The patent changes the physical parameters of the wafer through laser-induced modified layers and cracks. By altering the structural parameters (creating controlled cracks along dicing lines), the wafer becomes easier to divide with small forces, maintaining both productivity and chip quality without requiring large external forces that would cause chippings.
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
The method enables precise division of wafers into individual device chips with reduced loads and minimizes the occurrence of chippings or fragments, thereby maintaining the quality of the device chips.
Implementation Method 1
forming shield tunnels, each including a pore and a modified layer surrounding the pore, in the wafer by applying a first laser beam having a wavelength transmittable through the wafer
Implementation Method 2
forming a modified layer in the wafer along each of the projected dicing lines by applying a second laser beam having a wavelength transmittable through the wafer and a power output stronger than that of the first laser beam
Implementation Method 3
thereby inducing cracks in the wafer and exposing the cracks on the face side of the wafer along each of the projected dicing lines
Data Source
AI summary
A method of processing a wafer includes a first processing step of forming shield tunnels, each including a pore and a modified layer surrounding the pore, in the wafer by applying a first laser beam within the wafer in alignment with each of projected dicing lines, applying a second laser beam having a power output stronger than that of the first laser beam while positioning a focused spot thereof within the wafer in alignment with each of the projected dicing lines, at intervals smaller than intervals at which the shield tunnels have been formed in the wafer, thereby inducing cracks in the wafer along each of the projected dicing lines, and dividing the wafer into individual device chips by applying an external force to the wafer.