Ultrathin Epitaxial Layer Handling via Rigid Support and Selective Release
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Solution Overview
Problem
Current methods for handling ultrathin materials, such as epitaxial layers, lack robust and cost-effective solutions for support and separation, often resulting in stress-induced distortions and difficulties in cleaning due to harsh separation techniques and inadequate rigidity.
Innovation Solution
A multi-layer system is employed, comprising a growth substrate, an ultrathin layer, a reinforcing carrier material, and a bonding composition, where the bonding composition is used to adhere the ultrathin layer to a carrier substrate, allowing for structural support and easy separation without stress, using materials like polysulfones and cyclic olefin polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polymeric bonding material is used to temporarily bond thin wafers to a carrier, then the wafers can be handled and processed, but the bonding material flows at bonding temperatures causing wrinkles and distortions in ultrathin epitaxial layers
Solution Approach 1:
A rigid support layer is introduced as an intermediary between the ultrathin epitaxial layer and the polymeric bonding material. This support layer prevents the epitaxial layer from contacting and distorting with the flowing bonding material while still allowing temporary bonding to occur. The support layer acts as a mediator that enables handling without compromising layer flatness.
Solution Approach 2:
The system uses a composite structure combining the ultrathin epitaxial layer with a rigid support layer to create a temporarily bonded assembly. This composite material approach allows the thin layer to gain rigidity from the support layer during bonding operations, preventing wrinkles and distortions while maintaining the integrity of the epitaxial layer.
2Ease of manufacture
If laser lift-off or bulk chemical etch is used to separate epitaxial layers from growth substrates, then separation is achieved, but the process becomes highly traumatic causing stress and distortion
Solution Approach 1:
The system segments the separation function from the growth substrate by using a dedicated release layer that is specifically designed to be selectively removed. This allows separation to occur at the release layer interface rather than through traumatic laser lift-off or bulk etching of the entire growth substrate, reducing stress and distortion on the epitaxial layer.
Solution Approach 2:
A release layer serves as an intermediary between the epitaxial layer and the growth substrate, enabling clean separation. This release layer can be selectively removed through gentle means such as oxygen plasma or selective etching, providing a non-traumatic separation method that avoids the high temperatures and harsh chemicals of traditional methods.
3Device complexity
If a single-layer carrier system is used to support ultrathin materials, then simplicity is maintained, but robust support and easy separation cannot be simultaneously achieved
Solution Approach 1:
The carrier system is segmented into multiple functional layers including a rigid support layer, a release layer, and a bonding layer. Each layer performs a specific function: the rigid support layer provides mechanical strength, the release layer enables clean separation, and the bonding layer facilitates temporary attachment. This segmentation allows both robust support and easy separation to be achieved simultaneously.
Solution Approach 2:
The multi-layer carrier system provides multiple functions within a single integrated structure. The rigid support layer provides mechanical support, the release layer enables separation, and the bonding layer enables temporary attachment. This multi-functional design allows the system to achieve robust support, easy separation, and reliable handling all in one carrier assembly.
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 provides a robust and cost-effective means to handle ultrathin layers, maintaining structural integrity during processing and enabling clean separation without distortion, addressing the limitations of existing techniques.
Implementation Method 1
a bonding composition adjacent the carrier surface... The bonding composition of the carrier stack is in contact with the reinforcing material of the active stack
Data Source
AI summary
New temporary bonding methods and articles formed from those methods are provided. In one embodiment, the methods comprise coating a device or other ultrathin layer on a growth substrate with a rigid support layer and then bonding that stack to a carrier substrate. The growth substrate can then be removed and the ultrathin layer mounted on a final support. In another embodiment, the invention provides methods of handling device layers during processing that must occur on both sides of the fragile layer without damaging it. This is accomplished via the sequential use of two carriers, one on each side of the device layer, bonded with different bonding compositions for selective debonding.