Ultrasound Cavitation Planarization for Smart Cut Substrates
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Solution Overview
Problem
The challenge in micro-technology is the formation of non-transferred zones during the fracture step in the Smart Cut process, leading to incomplete detachment of thin films from donor substrates due to edge chamfering and surface defects, which requires complex planarization treatments to recycle the substrates effectively.
Innovation Solution
A process involving the use of ultrasound cavitation in a bath with specific frequency and power settings to planarize the surface exposed by fracture, allowing for the elimination of residual non-transferred zones without damaging the substrate, enabling direct recycling or simplified mechanical-chemical polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical polishing and chemical attack are used to planarize the substrate surface, then the surface flatness is improved, but the process complexity and treatment time increase
Solution Approach 1:
The patent replaces mechanical polishing and chemical attack with ultrasonic cavitation. The ultrasonic waves generate cavitation bubbles in the liquid medium that collapse near the substrate surface, creating micro-jets and shock waves that remove non-transferred zones. This acoustic field-based approach substitutes the complex mechanical-chemical planarization system with a simpler ultrasonic treatment system, reducing process complexity while achieving the same surface flatness improvement.
2Manufacturing precision
If mechanical polishing and chemical attack are used to planarize the substrate surface, then the surface flatness is improved, but the treatment time increases
Solution Approach 1:
The ultrasonic cavitation process replaces time-consuming mechanical polishing and chemical attack operations. The cavitation bubbles collapse rapidly, generating intense localized energy that efficiently removes non-transferred zones in a fraction of the time required for mechanical-chemical planarization. This substitution dramatically reduces the treatment time while maintaining the surface flatness improvement.
3Manufacturing precision
If localized planarization treatments are applied to non-transferred zones, then the surface quality is improved, but the device complexity and operational difficulty increase
Solution Approach 1:
The ultrasonic cavitation treatment provides a universal solution that handles both localized non-transferred zones and overall surface planarization with a single process. The liquid medium allows ultrasonic waves to reach all areas of the substrate surface uniformly, eliminating the need for complex localized treatment procedures. This multi-functional approach simplifies operation while improving surface quality across the entire substrate.
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 effectively removes non-transferred zones, facilitating the reuse of donor substrates with improved surface quality, reducing the need for complex localized treatments and enabling efficient recycling for further micro-technological processes.
Implementation Method 1
the application of ultrasounds or microwaves of power and frequency judiciously chosen
Implementation Method 2
Process for planarisation by ultrasounds of a substrate whose surface was released by fracture
Data Source
Figure 1~2
Figure 3~4
AI summary
A planarization process for a micro-technological substrate having a face freed by fracture along a layer weakened by implantation, includes, in view of a new cycle of implantation and fracture, a step in which this face is placed in the presence of a bath and ultrasound is applied to it at a frequency between 10 kHz and 80 kHz under conditions suitable for causing cavitation along said face; preferably, in particular in the case of a silicon substrate, the ultrasound is applied under the following conditions: - ultrasound power/bath volume > 5 W/L - power > 10 W - duration > 1 min - temperature between 1°C and 100°C.