Wafer Dicing Using Segmented Laser and Diamond Blade Cutting
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Solution Overview
Problem
Current methods for dicing wafers of light emitting devices are inefficient, particularly when dealing with materials like glass and wavelength converting layers, as they result in significant waste of expensive epitaxial material due to wide kerf widths and heat generation issues with metal-bonded blades.
Innovation Solution
A method involving multiple cutting steps using a thin, metal-bonded diamond grit dicing blade to maintain blade sharpness and a self-dressing effect, combined with laser ablation or mechanical sawing, to achieve narrow kerf widths and reduce material waste, with the transparent layer being diced in a way that it has a smaller lateral extent than the light emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a metal-bonded diamond grit blade is used for dicing the wafer, then the dicing process can be performed, but the blade becomes dull quickly and generates heat, reducing cutting precision and increasing material waste
Solution Approach 1:
The dicing process is divided into multiple sequential steps: first dicing through the transparent layer and wavelength converting layer, then flipping the wafer and dicing through the remaining thickness. This segmentation allows each cutting pass to be optimized for the specific materials being cut, maintaining blade sharpness and cutting precision throughout the process
Solution Approach 2:
The dicing blade parameters (such as depth of cut, speed, and pressure) are dynamically adjusted between cutting steps. The blade is repositioned and process parameters are modified after each cutting phase to optimize performance for the remaining materials, preventing blade dulling and heat generation that would reduce precision
2Productivity
If a wide kerf width is used for dicing, then the cutting process is faster, but expensive epitaxial material is wasted
Solution Approach 1:
The kerf width parameter is optimized by using a thin dicing blade and adjusting cutting parameters to achieve narrow kerf widths. The process parameters are changed between cutting steps to maintain optimal kerf width while completing the full thickness cut, minimizing material waste without sacrificing overall productivity
3Productivity
If heat is generated during dicing, then the cutting process continues, but the wavelength converting layer and transparent layer are damaged
Solution Approach 1:
The cutting process is segmented into multiple passes through different layers. By cutting through the transparent layer and wavelength converting layer separately from the remaining wafer thickness, heat generation is distributed and managed, preventing thermal damage to the sensitive optical layers
Solution Approach 2:
The dicing process uses periodic action with alternating cutting steps and intermediate handling (including flipping the wafer). This periodic interruption allows heat dissipation between cutting phases, preventing cumulative thermal damage while maintaining overall process efficiency
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 minimizes waste of expensive epitaxial material, maintains blade sharpness through self-dressing, and allows for precise dicing of wafers with narrow kerf widths, enhancing the efficiency and cost-effectiveness of the dicing process.
Implementation Method 1
sawing the wafer in a region of dielectric with a metal-bonded diamond grit blade
Implementation Method 2
combined with laser ablation or mechanical sawing, to achieve narrow kerf widths
Data Source
Figure 1~3
Figure 4A~5B
Figure 6A~7B
AI summary
The application discloses a method to dice laminates of a transparent layer, a phosphour layer and layer with semi-conductor light emitting devices separated by a dielectric. The dicing comprises two steps, where a laser is cutting the dielectric between the semiconductor elements and a different method (sawing with a diamond blade or breaking) is used to separate the remainder of the laminate.