III-N Multichip Module Release Layer for Laser Separation
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Solution Overview
Problem
The process of transferring and combining multichip modules from diverse substrates via substrate bonding is challenging due to mechanical damage and irregular separation, leading to dysfunctional devices, and existing methods require mechanical forces that can damage the devices and leave residual layers.
Innovation Solution
Incorporating a release layer in the material stack, which can be removed using laser ablation, allowing for non-mechanical separation of multichip modules, such as group III-N transistors and LEDs, without damaging the devices and facilitating uniform substrate processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical bonding and separation processes are used to transfer multichip modules, then substrate bonding can be achieved, but mechanical damage and irregular separation occur leading to dysfunctional devices
Solution Approach 1:
The patent replaces mechanical separation processes with laser-induced thermal separation. A laser beam is used to locally heat and separate the source substrate from the multichip modules, eliminating the need for mechanical forces that cause damage. This substitution of mechanical action with thermal/optical action resolves the contradiction between achieving substrate bonding and avoiding mechanical damage to devices.
Solution Approach 2:
The patent changes the physical state and properties of materials through controlled thermal parameters. By using laser heating to raise the temperature locally at the substrate-release layer interface, the bonding strength is temporarily reduced enabling separation. This parameter change from ambient temperature to elevated temperature allows clean separation without mechanical stress, protecting device integrity.
2Productivity
If abrasive post release mechanical processes are used, then separation can be achieved, but device damage and irregularity in separation increase
Solution Approach 1:
The patent replaces abrasive mechanical separation with laser-induced thermal separation. The laser beam scans across the substrate surface, providing uniform and controlled separation without mechanical contact. This eliminates irregularity in separation while maintaining high throughput, as the laser can rapidly process large areas without the limitations of mechanical tools.
Solution Approach 2:
The laser separation process uses periodic scanning motion of the laser beam across the substrate. This periodic action ensures uniform heating and separation across the entire substrate surface, achieving consistent separation quality throughout. The rhythmic back-and-forth motion of the laser maintains uniform separation while enabling rapid processing of large substrate areas.
3Ease of manufacture
If transparent and release layer is used, then separation can be facilitated, but additional manufacturing steps are required
Solution Approach 1:
The patent introduces a release layer as an intermediary between the source substrate and the multichip modules. This release layer has specific properties that allow it to bond to the substrate during fabrication but release easily under laser heating. The intermediary layer facilitates the separation process by providing a controlled interface for thermal release, making the overall manufacturing easier despite the added structural complexity.
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 method enables reliable and high-throughput separation of multichip modules with structural and electrical integrity, reducing mechanical stress and allowing for bonding of substrates with different sizes and material systems, such as GaN-based chips with silicon-based chips.
Implementation Method 1
the release layer is removed by a variety of laser ablation methods rendering devices with structural and electrical integrity
Implementation Method 2
a laser beam is rastered onto a back surface of the source substrate at a pulse rate between 0.1 picoseconds to 10 picoseconds per pulse with an energy between 1 micro Joules and 5 micro Joules per pulse
Data Source
AI summary
A device includes a layer including a first III-Nitride (III-N) material, a channel layer including a second III-N material, a release layer including nitrogen and a transition metal, where the release layer is between the first III-N material and the second III-N material. The device further includes a polarization layer including a third III-N material above the release layer, a gate structure above the polarization layer, a source structure and a drain structure on opposite sides of the gate structure where the source structure and the drain structure each include a fourth III-N material. The device further includes a source contact on the source structure and a drain contact on the drain structure.