Stealth Wafer Dicing With Non-Gaussian Laser Pulses
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Solution Overview
Problem
Conventional laser cutting processes for wafers often damage surrounding regions and semiconductor devices due to excessive melting during the cutting process, leading to increased manufacturing costs and reduced yield.
Innovation Solution
A wafer processing apparatus utilizing a laser beam with non-Gaussian pulses, focused internally within the wafer, to induce precise internal breakage through nonlinear absorption, minimizing surface damage and enhancing dicing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional laser cutting process is used with high absorption rate wavelength, then cutting capability is improved, but surrounding region melting and semiconductor device damage occur
Solution Approach 1:
The patent changes the temporal parameters of the laser beam by using pulsed laser operation with specific pulse widths (1 ps to 500 ns) and controlling the duty cycle. This temporal parameter change allows the laser energy to be delivered in short bursts, creating internal breakage through nonlinear absorption while minimizing heat diffusion to surrounding regions, thus resolving the contradiction between cutting capability and preventing damage
Solution Approach 2:
The patent employs periodic pulsed laser action instead of continuous wave laser. The pulsed operation with controlled pulse width and repetition rate enables the laser to create internal breakage during the pulse peak while allowing heat dissipation during the off-period, preventing cumulative heat damage to surrounding regions and semiconductor devices while maintaining effective cutting capability
2Manufacturing precision
If laser beam is focused inside the wafer for stealth dicing, then internal breakage is induced, but precise control of pulse timing is required
Solution Approach 1:
The patent utilizes parameter changes in the laser pulse characteristics, specifically employing non-Gaussian pulse shapes with controlled rise times (1% to 50% of FWHM) and specific full width at half maximum values (1 ps to 500 ns). These parameter specifications enable precise control of where and how the internal breakage occurs, achieving high manufacturing precision while providing clear guidelines for control system design
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 solution improves the reliability and yield of semiconductor device manufacturing by effectively forming internal breakages within the wafer without damaging the semiconductor devices, maintaining high precision and speed in the stealth dicing process.
Implementation Method 1
A wafer processing apparatus utilizing a laser beam with non-Gaussian pulses, focused internally within the wafer, to induce precise internal breakage through nonlinear absorption
Implementation Method 2
The cutting process using a laser beam according to the related art cuts the workpiece by irradiating the workpiece with laser light of a wavelength band having a high absorption rate and heating and melting the workpiece
Implementation Method 3
When a wafer is melted and cut, there is a problem in that not only a cutting region but also a surrounding region is melted
Data Source
AI summary
A wafer processing apparatus includes: a laser apparatus configured to generate a laser beam; a focusing lens optical system configured to focus the laser beam on an inside of a wafer; an arbitrary wave generator configured to supply driving power to the laser apparatus; and a controller configured to control the arbitrary wave generator, wherein the laser beam includes a plurality of pulses sequentially emitted from the laser apparatus, and wherein each of the plurality of pulses is a non-Gaussian pulse, and a full width at half maximum (FWHM) of each of the plurality of pulses ranges from 1 ps to 500 ns.