End Effector Pad Diaphragm for Bowed Wafer Handling
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Solution Overview
Problem
Semiconductor wafer processing tools face issues with substrate slippage during transfer due to improper securing, leading to risks like breaking, misalignment, and tool errors, especially with bowed substrates that challenge conventional elastomeric end effector pads in terms of temperature compatibility and precision.
Innovation Solution
An end effector pad design featuring a center portion, ring, and diaphragm made of high-modulus material, with rib regions and hard-stop structures, providing friction and vacuum-assisted clamping to securely hold substrates while accommodating bowed substrates and withstanding high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional elastomeric end effector pads are used, then flexibility and conformability to substrate surface is improved, but temperature compatibility and precision are worsened
Solution Approach 1:
The patent changes the material parameter from elastomeric (soft, temperature-sensitive) to rigid (hard, temperature-resistant) while maintaining the necessary adaptability through geometric design rather than material compliance. The rigid material has superior temperature compatibility for semiconductor processing environments.
Solution Approach 2:
The patent uses a curved or bowed reference surface that matches the expected substrate curvature. This allows a rigid pad to conform to bowed substrates without requiring elastomeric material, resolving the contradiction between rigidity for temperature resistance and conformability for secure contact.
2Temperature
If rigid end effector pads are used, then temperature resistance and structural stability are improved, but ability to accommodate bowed substrates is worsened
Solution Approach 1:
The reference surface is designed with a curvature that matches the expected bow of semiconductor substrates. This curved geometry allows rigid pads to maintain full contact with bowed substrates, accommodating substrate deformation without requiring flexible materials.
Solution Approach 2:
The pad structure incorporates localized features such as rib regions with varying thickness that provide targeted compliance in specific areas while maintaining overall rigidity. This allows the rigid pad to adapt to substrate bow locally while preserving global structural stability and temperature resistance.
3Force
If end effector pads use vacuum clamping, then securing force is improved, but risk of substrate slippage under high friction conditions is worsened
Solution Approach 1:
The patent changes the clamping mechanism from pure vacuum suction to vacuum-assisted friction clamping. By introducing a rigid reference surface that contacts the substrate edge, the system converts some vacuum holding force into mechanical friction resistance, preventing slippage during substrate transfer.
Solution Approach 2:
The end effector pad combines vacuum sealing capability with a rigid friction surface in a composite structure. The diaphragm provides vacuum sealing while the rigid center portion with reference surface provides friction contact, creating a dual-mechanism securing system that prevents both leakage and slippage.
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 solution ensures secure and precise substrate handling by maintaining contact with bowed substrates, preventing slippage and misalignment, and maintaining dimensional accuracy and temperature resistance, thus enhancing the reliability of semiconductor wafer processing.
Implementation Method 1
the diaphragm may be provided that flexes to allow the ring to conform to a bowed substrate
Implementation Method 2
the substrate sits on end effector pads located on the end effector. The end effector pads may be used to secure the substrate to the wafer handling robot through the use of vacuum and frictional force
Implementation Method 3
one or more hard-stop structures. A surface of the ring that is furthest from the center portion and offset from the diaphragm along the longitudinal axis may define a first reference plane
Implementation Method 4
the diaphragm may include at least three rib regions in which the thickness of the diaphragm is thicker than in regions of the diaphragm in between the rib regions
Data Source
AI summary
End effector pads are provided that may be used to secure substrates to an end effector on a wafer handling robot. An end effector may have a plurality of end effector pads. Each of the end effector pads may have a thin diaphragm that allows a peripheral ring of the pad to tilt slightly to allow the ring to seal against a bottom surface of a bowed substrate. A vacuum may be used to pull down the substrate against a hard-stop on each end effector pad and hold the substrate more securely. The hard-stop may be used to consistently locate the z-position of the bottom surface of the substrate relative to the end effector.