Flexible Chuck Cleaving System for Uniform SOI Wafer Thickness
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Solution Overview
Problem
The existing methods for cleaving bonded wafer pairs to produce silicon-on-insulator (SOI) wafers result in non-uniform thickness and roughness due to varying cleave propagation speeds and mechanical forces, requiring additional costly and time-consuming processing steps to achieve uniformity.
Innovation Solution
A system utilizing a flexible chuck and an actuator to control the cleaving process, with movable rollers that adjust the force application along the chuck to ensure a constant and controlled propagation of the cleave plane, thereby maintaining uniform thickness and roughness of the resulting SOI wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical force is applied by suction cups to pull the donor wafer apart, then the cleaving process can be initiated, but the cleave propagates at varying speeds causing non-uniform thickness and roughness
Solution Approach 1:
The patent applies dynamics by making the chuck flexible rather than rigid, allowing it to adapt to the cleaving process in real-time. The flexible chuck comprises a flexible substrate with suction cups that can deform and distribute force dynamically as the cleave propagates, ensuring uniform cleave speed and consistent layer thickness without requiring rigid mechanical structures.
Solution Approach 2:
The patent changes the physical parameter of the chuck from rigid to flexible, fundamentally altering how force is applied during cleaving. This parameter change allows the system to maintain consistent cleave propagation speed by adapting the force distribution according to the evolving stress state during the cleaving process, thereby achieving uniform layer thickness.
2Productivity
If mechanical force is applied by suction cups to separate the layers, then the cleaving can occur, but additional processing steps are required to reduce thickness variation and smooth the layer
Solution Approach 1:
The flexible chuck performs the function of both gripping and controlling cleave propagation uniformly, eliminating the need for separate processing steps to correct thickness variations. The system is self-regulating through the flexible substrate's ability to distribute force evenly, thereby reducing overall device complexity and increasing productivity by achieving uniform layers in a single cleaving operation.
3Manufacturing precision
If a rigid chuck is used to apply force, then the structure is simple, but the cleave propagation speed varies causing non-uniform thickness
Solution Approach 1:
The patent replaces the static rigid structure with a dynamic flexible structure that can adapt during the cleaving process. The flexible substrate allows the chuck to conform to the changing stress distribution, maintaining uniform cleave propagation speed and consistent layer thickness, thereby justifying the increased structural complexity through superior manufacturing precision.
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
The controlled cleaving process significantly reduces or eliminates non-uniform thickness and roughness variations in the SOI wafers, enhancing the efficiency and quality of the wafer production by maintaining a constant rate of cleave propagation.
Implementation Method 1
an actuator attached to the flexible chuck for application of force on the flexible chuck. The application of force on the flexible chuck causes the cleaving of the bonded wafer pair
Implementation Method 2
a movable roller positionable adjacent the actuator for application of force on the flexible chuck and movable along the flexible chuck. The position of the roller controls the propagation of the cleave of the bonded wafer pair
Implementation Method 3
a vacuum source and a vacuum distribution system coupled to the vacuum source and configured to supply the vacuum to the plurality of vacuum ports
Data Source
AI summary
Systems and methods are provided for mechanically cleaving a bonded wafer pair by controlling the rate of cleaving. This controlled rate of cleaving results in a reduction or elimination of non-uniform thickness variations in the cleaved surface of the resulting SOI wafer. One embodiment uses flexible chucks attached to the faces of the wafers and actuators attached to the flexible chucks to cleave the bonded wafer pair. Other embodiments also use rollers in contact with the surfaces to control the rate of cleaving.