Flexible Support Pins for Semiconductor Wafer Thermal Bowing
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Solution Overview
Problem
Conventional support systems for semiconductor wafers during heat-treating processes are inadequate as they fail to manage thermally-induced motion, leading to stress and damage due to rigid pins that cannot withstand rapid thermal expansion, causing the wafer to deform into a dome shape and potentially break or launch vertically.
Innovation Solution
A method and apparatus that allow thermally-induced motion of the workpiece by using moveable engagement portions of support members, which are resilient and flexible, allowing the wafer to deform naturally and reducing stress while maintaining support, and include actuators to adjust positions and suppress vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid support pins are used to support the semiconductor wafer, then the wafer is held in position, but the pins cannot withstand the rapid thermal expansion forces, causing the wafer to deform and potentially break
Solution Approach 1:
The support pins are changed from rigid to flexible, altering the mechanical property parameter of the support structure. This allows the pins to deflect under thermal load rather than breaking, while still providing adequate support to prevent wafer damage.
Solution Approach 2:
The flexible support pins are designed in advance to accommodate the expected thermal expansion forces. The flexibility acts as a pre-planned cushioning mechanism that absorbs the shock of rapid thermal bowing before it can transmit damaging forces to the wafer.
2Ease of operation
If rigid support pins contact the wafer, then the wafer is supported, but thermally-induced motion causes stress and damage to the wafer
Solution Approach 1:
The support system is changed from static (rigid pins) to dynamic (flexible pins that can deflect). The flexible pins move with the wafer during thermal bowing, maintaining contact and support while accommodating the thermally-induced motion that would otherwise cause stress and damage.
3Temperature
If the wafer is rapidly heated to high temperature, then the annealing process is effective, but the support system breaks due to inability to withstand thermal expansion forces
Solution Approach 1:
The support pin material or structure is modified to change its mechanical properties, specifically to increase flexibility. This allows the support system to withstand the high temperature annealing process by deflecting under thermal load rather than breaking.
4Manufacturing precision
If conventional support pins are used, then the wafer is supported at the exclusion zone, but the pins break when the wafer launches vertically due to rapid thermal expansion
Solution Approach 1:
The support pins are made dynamic and flexible to accommodate the rapid vertical motion of the wafer during thermal expansion. The flexible pins can deflect and recover, maintaining support during the launch and preventing breakage while keeping the wafer positioned at the exclusion zone.
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 stress and prevents damage by allowing natural deformation of the wafer, maintaining it within a desired region, and suppressing vibrations, enabling higher peak temperatures without breaking the support system.
Implementation Method 1
rapidly heating the device side surface of the wafer to a substantially higher annealing temperature, at a rate much faster than a thermal conduction time through the wafer... cause the device side to thermally expand at a greater rate than the rest of the wafer
Implementation Method 2
include actuators to adjust positions and suppress vibrations
Data Source
AI summary
Apparatuses and methods for supporting a workpiece such as a semiconductor wafer. A support system is configured to support the workpiece while allowing thermally-induced motion of the workpiece, which may include thermal bowing or thermal bending. The system may include a support member having a moveable engagement portion engageable with the workpiece, the engagement portion being moveable to allow the thermally-induced motion of the workpiece while supporting the workpiece. The moveable engagement portion may include a plurality of moveable engagement portions of a plurality of respective support members, which may be resiliently engageable with the workpiece. The support members may include flexible support members each having an unconstrained portion and a constrained portion, and the moveable engagement portions may include the unconstrained portions. Alternatively, the support members may be rigid and the system may include a plurality of force applicators such as springs in communication with the support members.