Wafer Crack Detection Using Coating Repulsion Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for forming cracks in wafers to facilitate division into individual device chips are inefficient, requiring frequent adjustments of laser processing conditions and visual inspection with a microscope, leading to poor productivity when cracks do not reach the opposite side of the wafer.
Innovation Solution
A crack detection method involving the application of a laser beam to form modified layers and cracks within the wafer, followed by applying a coating material to detect crack formation by repelling patterns, allowing for immediate adjustment of processing conditions without the need for microscopic inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser processing conditions are adjusted to form cracks extending from modified layers to the front side of the wafer, then the wafer can be divided into individual device chips, but the process requires frequent adjustments and microscopic inspection, leading to poor productivity
Solution Approach 1:
The patent applies a coating material to the back side of the wafer that changes color or creates visible patterns when cracks form. This allows operators to visually detect crack formation without microscopic inspection, enabling quick assessment of laser processing effectiveness and maintaining high productivity while ensuring reliable crack formation.
Solution Approach 2:
The coating material acts as an intermediary between the internal crack formation process and external visual inspection. By applying this intermediate layer to the back side of the wafer, the patent makes the internal crack formation process visible from the outside, eliminating the need for time-consuming microscopic examination while maintaining reliable detection of crack formation.
2Measurement precision
If a microscope is used to check crack formation, then accurate detection is possible, but the inspection process becomes time-consuming and reduces productivity
Solution Approach 1:
The coating material on the back side of the wafer changes color or creates distinct visual patterns when cracks pass through it. This color change mechanism provides accurate crack detection through simple visual inspection, eliminating the need for time-consuming microscopic examination while maintaining reliable detection accuracy.
Solution Approach 2:
The coating material creates a visible copy or representation of the internal crack formation process on the back side of the wafer. This visual copy allows operators to assess crack formation accuracy quickly without direct microscopic observation of the internal modified layers, significantly reducing inspection time while maintaining detection precision.
3Manufacturing precision
If laser processing conditions are optimized for each wafer material and thickness, then appropriate crack formation is achieved, but frequent adjustments are required reducing productivity
Solution Approach 1:
The coating material provides immediate visual feedback on crack formation quality by displaying visible patterns or color changes on the back side of the wafer. This feedback mechanism allows operators to quickly assess whether laser processing conditions are producing appropriate cracks, enabling rapid adjustments without time-consuming microscopic inspection and maintaining both precision and productivity.
Solution Approach 2:
The coating material is applied to the back side of the wafer before laser processing to prepare for visual crack detection. This preliminary action enables immediate visual assessment of crack formation after laser treatment, allowing quick verification and adjustment of processing conditions for different wafer materials and thicknesses without losing 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
Enables easy detection of appropriate crack formation, improving productivity by allowing for real-time adjustments of laser processing conditions and ensuring effective crack formation without the use of microscopes.
Implementation Method 1
applying a laser beam of a wavelength having a transmitting property to the workpiece with a focal point of the laser beam being positioned inside the workpiece
Implementation Method 2
form a modified layer inside the workpiece and further form a crack extending from the modified layer
Implementation Method 3
detect the crack by searching for a portion where the coating material is linearly repelled
Implementation Method 4
a coating material applying step of applying a coating material to the second side after the crack forming step is performed
Data Source
AI summary
A crack detection method includes a crack forming step of applying a laser beam to a plate-shaped workpiece that has a first side and a second side opposite to the first side linearly from the first side with a focal point of the laser beam positioned inside the workpiece, the laser beam being of a wavelength having a transmitting property to the workpiece, to thereby form a modified layer inside the workpiece and further form a crack extending from the modified layer toward the second side, a coating material applying step of applying a coating material to the second side, and a crack detecting step of detecting the crack by searching for a portion where the coating material is linearly repelled.