Amorphous Carbon Coating on Handler Wafer for Laser Debonding
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Solution Overview
Problem
The existing methods for removing a handler wafer from a semiconductor device wafer are costly due to the use of expensive optically transparent wafers and require high heat budgets, often using UV lasers for ablation, which is inefficient and expensive.
Innovation Solution
The introduction of an amorphous carbon layer on the handler wafer, which absorbs infrared radiation and efficiently heats the adhesive layers, allowing for the separation of the handler wafer from the semiconductor device wafer with reduced heat intensity and cost, using silicon wafers as a more affordable alternative.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optically transparent wafers (glass, quartz, sapphire) are used for handler wafer, then laser ablation of bonding medium can be achieved, but cost increases significantly due to expensive materials and separate fabrication facilities
Solution Approach 1:
An amorphous carbon layer is introduced as an intermediary absorber layer on the handler wafer surface. This layer mediates the laser energy transfer by absorbing infrared radiation and converting it to thermal energy, which then heats the adhesive layer for debonding. This eliminates the need for expensive optically transparent wafers while maintaining effective laser-driven separation.
Solution Approach 2:
The invention replaces expensive, durable optically transparent wafers with a more economical approach using standard silicon handler wafers combined with a thin amorphous carbon coating. The carbon layer serves its purpose as a temporary heat absorber during the laser debonding process, enabling cost-effective handler wafer implementation.
2Reliability
If UV lasers are used for ablation of bonding medium, then handler wafer can be separated from semiconductor device wafer, but heat budget increases and process becomes less efficient
Solution Approach 1:
The invention changes the laser wavelength parameter from UV to infrared, and introduces an amorphous carbon layer that specifically absorbs infrared radiation. This parameter change enables more efficient energy coupling, as the carbon layer absorbs infrared energy and converts it directly to heat at the adhesive layer interface, reducing the overall heat budget required for separation.
Solution Approach 2:
The amorphous carbon layer undergoes phase transition or thermal decomposition when heated by infrared laser radiation, which facilitates the debonding process. The carbon layer acts as a thermal mediator that transforms optical energy into localized thermal energy, enabling efficient adhesive layer heating with reduced total energy input.
3Reliability
If high heat intensity is applied for debonding, then separation can be achieved, but damage to semiconductor devices may occur
Solution Approach 1:
The amorphous carbon layer is applied locally on the handler wafer surface at the adhesive interface. This localized absorber creates concentrated heating exactly where needed at the bond line, while the semiconductor devices remain relatively cool. The local quality of heat generation prevents collateral thermal damage to sensitive semiconductor structures.
Solution Approach 2:
The carbon layer serves as a thermal mediator that confines heat generation to the adhesive layer interface. By absorbing laser energy and converting it to localized heat at the bond line, it protects the semiconductor devices from direct exposure to high heat intensity, enabling safe and effective separation.
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 reduces the heat required for separation, minimizes the use of expensive optically transparent wafers, and localizes heating to prevent damage to semiconductor devices, thereby lowering costs and improving the efficiency of the wafer separation process.
Implementation Method 1
applying laser radiation to the handler wafer to cause heating of the amorphous carbon layer
Implementation Method 2
heating of the amorphous carbon layer that in turn causes heating of the adhesive layer
Data Source
AI summary
A method of removing a handler wafer. There is provided a handler wafer and a semiconductor device wafer having a plurality of semiconductor devices, the semiconductor device wafer having an active surface side and an inactive surface side. An amorphous carbon layer is applied to a surface of the handler wafer. An adhesive layer is applied to at least one of the amorphous carbon layer of the handler wafer and the active surface side of the semiconductor device wafer. The handler wafer is joined to the semiconductor device wafer through the adhesive layer or layers. Laser radiation is applied to the handler wafer to cause heating of the amorphous carbon layer that in turn causes heating of the adhesive layer or layers. The plurality of semiconductor devices of the semiconductor device wafer are then separated from the handler wafer.