Substrate Transport Coupling for Repeatable Wafer Placement
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Solution Overview
Problem
Conventional substrate transport apparatuses face challenges in achieving high precision and repeatability due to variability caused by thermal effects, motor hysteresis, and friction couplings, which affect the accurate placement of substrates in semiconductor processing.
Innovation Solution
The implementation of a substrate transport apparatus with a dimensionally substantially invariant interface at the torque couplings between the rotary drive member and the rotary follower member, which reduces friction and variability by providing a rigid, non-slip torque transfer mechanism, enhancing the repeatability and accuracy of substrate placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drive systems with motors, pulleys, and belts are used, then the substrate transport apparatus can operate with standard components, but the placement accuracy deteriorates to about 100 μm repeatability due to motor hysteresis and friction couplings
Solution Approach 1:
The patent replaces the conventional mechanical drive system (motors, pulleys, belts) with a direct-drive mechanism where a rotary drive member is rigidly coupled to a transport arm. This eliminates intermediate friction couplings and motor hysteresis, achieving better than 100 μm repeatability through dimensionally invariant interfaces that provide rigid torque transfer.
2Reliability
If friction couplings are used in the drive system, then the device structure is simpler, but variability increases due to thermal effects and motor hysteresis, worsening placement repeatability
Solution Approach 1:
The patent extracts and removes the friction couplings (belts, pulleys, gears) from the drive system, eliminating the source of variability caused by thermal effects and motor hysteresis. The rotary drive member is directly and rigidly coupled to the transport arm, creating a frictionless torque transfer path that achieves better than 100 μm repeatability.
Solution Approach 2:
The patent changes the torque coupling parameter from friction-based to rigid dimensionally invariant coupling. By using rigid interfaces with negligible dimensional change under thermal and operational variations, the system eliminates the harmful effects of thermal expansion and motor hysteresis that plague conventional friction-based couplings.
3Manufacturing precision
If rigid torque coupling is implemented to reduce motor hysteresis impact, then placement accuracy improves, but the device complexity increases due to precision coupling requirements
Solution Approach 1:
The patent merges the rotary drive member and transport arm into a single rigidly coupled unit, eliminating the need for separate coupling components. The dimensionally invariant interface integrates the drive and arm into one stiff structure that resists thermal and operational variations, achieving better than 100 μm repeatability without complex coupling mechanisms.
Data Source
AI summary
A substrate transport apparatus including, a torsional motion driver member having an exterior perimeter circumscribing an axis of rotation of the torsional motion driver member, and a torsional motion follower member including a body portion and a bearing collar rotatably coupled to the body portion, the torsional motion follower member being coupled to the torsional motion driver member with a dimensionally substantially invariant interface, wherein the bearing collar is decoupled from the exterior perimeter of the torsional motion driver member so that the exterior perimeter, as a whole, is free of the bearing collar.