Silicon Wafer Laser Processing Wavelength Optimization
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Solution Overview
Problem
Existing laser processing methods for silicon wafers using a 1,064 nm wavelength pulse laser beam fail to form a satisfactory deteriorated layer inside the wafer, leading to inefficient division along the dividing lines due to incomplete multiphoton absorption, resulting in high productivity losses.
Innovation Solution
A silicon wafer laser processing method utilizing a laser beam with a wavelength of 1,100 to 2,000 nm, preferably 1,300 to 1,600 nm, to form a deteriorated layer inside the wafer, employing a laser beam processing machine with a chuck table, laser beam application unit, and processing-feed means to efficiently create a permeable layer for smooth division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pulse laser beam with wavelength of 1,064 nm is used to form a deteriorated layer in the silicon wafer, then the laser beam can penetrate the workpiece, but multiphoton absorption is incomplete and a satisfactory deteriorated layer cannot be formed
Solution Approach 1:
The patent changes the wavelength parameter of the laser beam from 1,064 nm to the range of 1,100 to 2,000 nm (preferably 1,300 to 1,600 nm). This parameter change enables complete multiphoton absorption in silicon, forming a satisfactory deteriorated layer that facilitates smooth division while maintaining high productivity.
2Productivity
If a cutting blade with thickness of about 20 μm is used to cut the silicon wafer, then the wafer can be divided, but the dividing lines must have a width of about 50 μm, increasing the area ratio and reducing productivity
Solution Approach 1:
The patent replaces the mechanical cutting blade system with a laser-based deteriorated layer formation system. By applying a laser beam to create a deteriorated layer along the dividing lines, the wafer can be divided with much narrower line widths, increasing the usable chip area and productivity without sacrificing division precision.
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 effectively forms a deteriorated layer inside the silicon wafer, reducing the load required for division by up to 1/7 compared to traditional methods, enhancing productivity and division efficiency.
Implementation Method 1
the wavelength (1,064 nm) of the pulse laser beam corresponds to an intermediate range from a wavelength range having absorptivity for a silicon wafer up to a wavelength range having permeability for a silicon wafer. Therefore, when a pulse laser beam having a wavelength of 1,064 nm is applied along the dividing lines of a silicon wafer to form a deteriorated layer in the inside of the silicon wafer, multiphoton absorption is not completely carried out in the inside of the silicon wafer
Data Source
AI summary
A silicon wafer laser processing method for forming a deteriorated layer along dividing lines formed on a silicon wafer in the inside of the silicon wafer by applying a laser beam along the dividing lines, wherein the wavelength of the laser beam is set to 1,100 to 2,000 nm.