Embedded Die Packaging Laser Drilling Via Protection
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Solution Overview
Problem
Laser drilling of vias in embedded die packaging for semiconductor devices faces challenges due to increased absorption of laser energy by roughened metal surfaces, leading to overheating and damage, which is difficult to control and may require thick metal pads or additional protective areas, increasing costs and stress.
Innovation Solution
The use of a protective masking layer with different surface roughness regions on contact pads, where the first region is treated for laser drilling and the second region promotes adhesion of dielectric material, allowing for controlled laser drilling and minimizing damage by selectively absorbing less laser energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the metal pad surface is roughened to promote adhesion of dielectric material, then adhesion strength is improved, but laser energy absorption increases causing overheating and damage
Solution Approach 1:
The patent applies different surface treatments to different regions of the contact pad: the first region (peripheral area) is roughened to promote adhesion, while the second region (central area where vias are drilled) is kept smooth to reduce laser absorption. This local differentiation resolves the contradiction by giving each region the surface quality it needs for its specific function.
2Object-affected harmful factors
If thicker metal pads are used to reduce laser absorption, then overheating is reduced, but device stress increases
Solution Approach 1:
Instead of uniformly thickening the entire metal pad, the patent creates a smooth second region specifically in the via drilling area. This localized smooth region reduces laser absorption and prevents overheating during via formation, while the rest of the pad maintains its original thickness and structural integrity, avoiding increased device stress.
3Reliability
If additional protective areas are added to prevent damage, then device protection is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent incorporates protective functionality directly into the existing contact pad structure by creating a smooth second region within the pad itself. This eliminates the need for separate protective layers or additional structural elements, thereby protecting the device during laser drilling without increasing manufacturing complexity or cost.
Solution Approach 2:
The contact pad serves multiple functions: it provides electrical connection, promotes adhesion through roughened first regions, and protects against laser damage through smooth second regions. By making the pad multi-functional, the patent avoids adding separate protective components, thus reducing manufacturing complexity while improving device protection.
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 provides a larger process window for laser drilling, reducing the risk of overheating and damage while maintaining effective adhesion of dielectric materials, thus improving the fabrication of embedded die packaging without requiring significant changes to existing processes or increasing costs.
Implementation Method 1
laser drilling of vias through the package interconnect layer and package dielectric to expose contact pads
Implementation Method 2
increased absorption of laser energy by roughened metal surfaces, leading to overheating and damage
Data Source
AI summary
Embedded die packaging for semiconductor devices and methods of fabrication wherein conductive vias are provided to interconnect contact areas on the die and package interconnect areas. Before embedding, a protective masking layer is provided selectively on regions of the electrical contact areas where vias are to be formed by laser drilling. The material of the protective masking layer is selected to protect against over-drilling and/or to control absorption properties of surface of the pad metal to reduce absorption of laser energy during laser drilling of micro-vias, thereby mitigating physical damage, overheating or other potential damage to the semiconductor device. The masking layer may be resistant to surface treatment of other regions of the electrical contact areas, e.g. to increase surface roughness to promote adhesion of package dielectric.