Laser Workpiece Division via Modified Regions
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Solution Overview
Problem
The existing laser processing methods for dividing semiconductor wafers along division lines can result in inaccurate breaks, with the modified regions formed at the central portion of the workpiece leading to potential deviations from the intended division lines, affecting the die strength and yield of individual chips.
Innovation Solution
A laser processing method that forms first and second modified regions along the division lines and at intersecting regions, respectively, using a pulsed laser beam, followed by applying an external force through an expandable protective tape to accurately divide the workpiece into individual chips, ensuring precise alignment and reduced stress on functional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If first modified regions are formed at the central portion of the workpiece in the thickness direction, then the die strength of each chip is improved, but the break may proceed obliquely and deviate from the division lines
Solution Approach 1:
The patent divides the modified regions into two distinct types: first modified regions formed at the central portion in the thickness direction to enhance die strength, and second modified regions formed near the front side along the division lines to ensure accurate breaking. This segmentation allows each type of modified region to fulfill its specific function without interfering with the other, resolving the contradiction between strength improvement and breaking accuracy.
Solution Approach 2:
The patent applies different modifications to different locations within the workpiece. First modified regions are created at the central portion for strength enhancement, while second modified regions are created near the front side along the division lines for precise breaking control. This local differentiation of quality ensures that each region serves its intended purpose optimally.
2Productivity
If a pulsed laser beam is applied to form modified regions along division lines, then the workpiece can be divided, but the break may deviate from the intended division lines affecting yield
Solution Approach 1:
The patent segments the laser processing into two distinct operations: forming first modified regions at the central portion for structural integrity, and forming second modified regions near the front side along the division lines for precise breaking control. This segmentation ensures that productivity is maintained through efficient laser processing while breaking accuracy is improved by having dedicated modified regions at the division lines.
Solution Approach 2:
The patent performs preliminary laser processing to create both first and second modified regions before the actual breaking step. This preliminary action ensures that when the breaking force is applied, the workpiece will break precisely along the division lines with high accuracy, thereby improving reliability without compromising productivity.
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 enables accurate division of semiconductor wafers along intended lines, improving the die strength and yield of individual chips by forming modified regions strategically to control the breakage pattern and prevent oblique propagation, thus enhancing the reliability and efficiency of the semiconductor device fabrication process.
Implementation Method 1
applying a pulsed laser beam having a transmission wavelength to the workpiece along the first division lines and the second division lines to thereby form a plurality of first modified regions in the workpiece near the front side of the workpiece
Implementation Method 2
applying an external force to the workpiece after performing the first modified region forming step and the second modified region forming step to thereby divide the workpiece along the first division lines and the second division lines
Data Source
AI summary
A processing method for a workpiece which includes a first modified region forming step of forming first modified regions along first division lines and second division lines near the front side of the workpiece, a second modified region forming step of forming second modified regions at intersecting regions between the first division lines and the second division lines at predetermined positions between the back side of the workpiece and the first modified regions formed in the workpiece by performing the first modified region forming step, and a dividing step of applying an external force to the workpiece after performing the first and second modified region forming steps to thereby divide the workpiece along the first division lines and the second division lines into individual chips.