Laser Debonding of Silicon Carriers for Low-TTV Organic Interposers
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Solution Overview
Problem
Existing advanced packaging processes face challenges with high total thickness variation (TTV) and incompatibility with silicon wafer handling tools, and current carrier solutions are costly, risky, or limited by temperature constraints.
Innovation Solution
Employ a silicon carrier wafer with an IR-sensitive debond film that absorbs infrared radiation for precise laser ablation, allowing for low TTV and reusability, and uses multi-layer debond films to enhance absorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If glass wafers with organic adhesive and release layer are used as carriers, then assembly processes can be performed, but total thickness variation becomes high (up to approximately 5 μm or larger)
Solution Approach 1:
The patent changes the material parameter of the carrier from glass to silicon, and the debonding mechanism from thermal/UV decomposition to laser ablation. This parameter change resolves the contradiction by providing both assembly capability and low TTV (silicon carrier TTV is less than approximately 1 μm) simultaneously.
Solution Approach 2:
The patent uses a composite structure consisting of a silicon carrier wafer with a specially designed debond film layer. This composite material approach allows the silicon carrier to provide low TTV and mechanical stability, while the debond film enables controlled release through laser ablation, resolving the contradiction between assembly capability and thickness precision.
2Ease of manufacture
If glass wafers with organic adhesive and release layer are used as carriers, then assembly processes can be performed, but compatibility with silicon wafer handling tools is lost
Solution Approach 1:
The patent changes the carrier material from glass to silicon, fundamentally altering the material parameter to match the requirements of silicon wafer handling tools. This enables compatibility with standard silicon fabrication equipment while maintaining assembly process capability through the debond film mechanism.
Solution Approach 2:
The debond film acts as an intermediary layer between the silicon carrier and the interposer. It enables the silicon carrier to function in assembly processes that traditionally required glass carriers, while the silicon material itself provides compatibility with silicon wafer handling tools. The debond film mediates between these two requirements.
3Ease of operation
If silicon carrier wafer with grinding process is used, then carrier release can be achieved, but cost increases and risk of damage to overlying structure occurs
Solution Approach 1:
The patent extracts the debonding function into a separate debond film layer that is selectively removed through laser ablation. This separates the release function from the carrier structure itself, allowing the silicon carrier to be released without grinding that could damage the overlying interposer structure.
Solution Approach 2:
The patent replaces the mechanical grinding process with a laser-based ablation process. The laser selectively removes the debond film through photothermal ablation without mechanical contact, eliminating the risk of mechanical damage to the overlying structure while achieving carrier release.
4Ease of operation
If thermal release bonding film is used, then carrier release can be achieved, but temperature limit restricts interposer solutions (less than approximately 200° C.)
Solution Approach 1:
The patent replaces the thermal release mechanism with a laser ablation mechanism. Instead of relying on thermal decomposition at limited temperatures, the laser directly ablates the debond film through photothermal effects, enabling release without temperature constraints and allowing interposer solutions to operate above 200°C.
Solution Approach 2:
The laser ablation process utilizes phase transitions (vaporization) of the debond film material to achieve removal. This phase transition mechanism occurs at the laser focus point without requiring bulk heating, thereby eliminating the temperature limit constraint of thermal release films.
5Ease of operation
If thermal release bonding film is used, then carrier release can be achieved, but thickness uniformity remains poor (high TTV)
Solution Approach 1:
The patent uses a composite structure with a silicon carrier wafer (TTV less than approximately 1 μm) and a thin debond film layer. The silicon carrier provides excellent thickness uniformity, while the debond film enables release capability. This composite approach resolves the contradiction by combining the advantages of both materials.
Solution Approach 2:
The patent changes the release mechanism from thermal decomposition of thick organic layers to laser ablation of thin debond films. This parameter change in the debonding mechanism allows for much thinner release layers with superior thickness uniformity while maintaining release capability.
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
Achieves low TTV, improved thermal and mechanical stability, reduced assembly costs, and compatibility with silicon wafer handling tools, enabling high-density 2.5D and 3D integration.
Implementation Method 1
a laser, indicative by a wavelength within an infrared range, is shone on the backside surface of the carrier substrate to deactivate the debond film
Implementation Method 2
ablating at least a portion of the debond film with a laser, wherein a wavelength of the laser is within an infrared range
Data Source
AI summary
Embodiments disclosed herein comprise a method for assembling an interposer. In an embodiment, the method comprises assembling a structure over a carrier substrate, where the structure is mechanically coupled to the carrier substrate by a debond film. In an embodiment, the structure comprises an organic dielectric layer, and the debond film comprises an inorganic layer. The method may further comprise ablating at least a portion of the debond film with a laser. In an embodiment, a wavelength of the laser is within an infrared range. The method may further comprise separating the carrier substrate from the structure.