Laser Ablation for Semiconductor Package Fabrication
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Solution Overview
Problem
Current laser drilling methods for forming vias in semiconductor substrates lack precise control over depth and topography, and are inefficient in terms of laser energy usage, limiting the rapid formation of three-dimensional multichip modules.
Innovation Solution
A method involving two laser ablation processes is employed, where the first process forms features in a substrate by tuning the frequency, pulse width, and pulse energy of a pulsed laser beam based on the depth of the features, and the second process forms via-in-via in the dielectric material filled through-vias by similarly tuning the laser beam parameters, ensuring controlled depth and topography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If laser drilling is used to form vias in semiconductor substrates, then the speed and location accuracy are significantly improved compared to etching, but the depth control and topography control are not precise enough
Solution Approach 1:
The patent applies periodic pulsed laser action instead of continuous laser drilling. By using repeated pulses with controlled parameters (pulse width, frequency, energy), the method achieves both high speed (through rapid pulsing) and precise depth control (through cumulative material removal at controlled intervals). This resolves the contradiction by making the laser action periodic rather than continuous.
Solution Approach 2:
The patent dynamically adjusts laser parameters (pulse width, frequency, energy) based on the drilling depth and material being processed. This parameter optimization allows the system to maintain high speed while achieving precise depth and topography control, directly resolving the contradiction between speed and precision.
2Measurement precision
If conventional laser drilling is used to form vias, then the location accuracy is improved, but the laser energy usage efficiency is low leading to low ablation rates
Solution Approach 1:
The patent optimizes laser parameters (pulse width, frequency, energy) to maximize ablation efficiency while maintaining location accuracy. By tuning these parameters according to the specific material and desired via characteristics, the system achieves both precise positioning and high ablation rates, resolving the contradiction between precision and productivity.
Solution Approach 2:
The use of periodic pulsed laser action with optimized timing and duration allows for efficient energy delivery. The pulsed nature enables thermal relaxation between pulses, reducing wasted energy while maintaining high ablation rates, thus resolving the contradiction between location precision and ablation productivity.
3Measurement precision
If laser drilling is used to form vias with controlled depth, then the location accuracy is improved, but the topography control is not achieved
Solution Approach 1:
The patent adjusts laser parameters (pulse width, energy, frequency) based on the desired via depth and topography. By optimizing these parameters, the system achieves both precise location accuracy and controlled topography (smooth walls, proper taper), resolving the contradiction between location precision and shape control.
Solution Approach 2:
The periodic pulsed laser action with controlled interval and duration enables gradual material removal that maintains both location accuracy and desirable topography. The pulsing allows for controlled melting and ejection of material, achieving smooth via walls and proper geometry while maintaining precise positioning.
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 enables rapid and precise formation of features in semiconductor substrates, enhancing the efficiency of laser drilling and improving the accuracy of via formation for three-dimensional multichip modules.
Implementation Method 1
forming one or more features including one or more cavities and one or more through-vias in a substrate by a first laser ablation process
Implementation Method 2
forming a via-in-via in the dielectric material filled in each of the one or more through-vias by a second laser ablation process
Data Source
AI summary
A method of fabricating a frame to enclose one or more semiconductor dies includes forming one or more features including one or more cavities and one or more through-vias in a substrate by a first laser ablation process, filling the one or more through-vias with a dielectric material, and forming a via-in-via in the dielectric material filled in each of the one or more through-vias by a second laser ablation process. The one or more cavities is configured to enclose one or more semiconductor dies therein. In the first laser ablation process, frequency, pulse width, and pulse energy of a first pulsed laser beam to irradiate the substrate are tuned based on a depth of the one or more features. In the second laser ablation process, frequency, pulse width, and pulse energy of a second pulsed laser beam to irradiate the dielectric material are tuned based on a depth of the via-in-via.