Bernoulli Wafer Transfer Flow Control to Prevent Thin Wafer Chipping
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Solution Overview
Problem
Thin wafers used in semiconductor manufacturing are prone to chipping or cracking during transfer due to their large warpage and the high suction force exerted by Bernoulli manipulators.
Innovation Solution
A transfer method for thin wafers that uses a Bernoulli manipulator equipped with a gas path to adjust gas flow rates based on the wafer's thickness. During transfer from the wafer cassette, a lower gas flow rate is used to reduce suction force and prevent warping, while a higher flow rate is used during transfer to the processing chamber to ensure stable suction and prevent slipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Bernoulli manipulator uses high gas flow rate to ensure stable suction of thin wafer, then the wafer can be firmly held during transfer, but the suction force causes large warpage and leads to chipping or cracking of the wafer
Solution Approach 1:
The patent applies dynamics by making the gas flow rate adjustable during the transfer process. The system transitions from a static high flow rate to a dynamic controlled flow rate that decreases as the wafer moves away from the cassette, allowing firm initial suction followed by reduced warpage force
Solution Approach 2:
The patent implements periodic action by dividing the transfer process into distinct phases with different gas flow rates: initial suction phase with high flow rate, transition phase with decreasing flow rate, and final transfer phase with low flow rate, optimizing both suction stability and wafer protection
2Strength
If a Bernoulli manipulator uses low gas flow rate to reduce warpage and prevent chipping, then the wafer can be transferred safely, but the suction force is insufficient and the wafer may slip during transfer
Solution Approach 1:
The patent applies preliminary action by providing high gas flow rate at the beginning of the transfer process to ensure firm initial suction of the wafer onto the manipulator before reducing the flow rate, preventing slippage during the critical pickup phase
3Device complexity
If the gas flow rate is kept constant during the entire transfer process, then the control system is simple, but it cannot simultaneously ensure stable suction and prevent wafer chipping
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gas flow rate parameter during the transfer process based on the wafer's position and transfer stage, transitioning from constant flow rate to variable flow rate control to simultaneously achieve stable suction and prevent chipping
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 method effectively reduces the risk of chipping or cracking during transfer by managing the suction force and warping deformation of thin wafers, while ensuring stable transfer to the processing chamber.
Implementation Method 1
Bernoulli manipulator is usually used to transfer the wafer, and the corresponding gas flow is provided to the Bernoulli manipulator
Data Source
AI summary
The present invention discloses a transfer method of thin wafer. For thin wafers with different thicknesses, in different transfer stages, a Bernoulli manipulator uses different gas flow rates, so that the problem of chipping of wafers during transfer is solved. Specifically, in a process of moving a wafer out of a wafer cassette, a Bernoulli manipulator uses a small gas flow rate, so as to reduce the suction force on the wafer and weaken warping deformation of the wafer, thereby reducing the risk of cracking or chipping in the process of moving the wafer out of the wafer cassette; after the wafer is moved out of the wafer cassette and in a process of transferring same to a processing chamber, the Bernoulli manipulator uses a large gas flow rate, so as to increase the suction force on the wafer, thereby ensuring the wafer can be stably suctioned on the Bernoulli manipulator during transfer, and avoiding wafer slipping.