Dual End Effector Wafer Swapping With Constant-Velocity Arc Motion
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Solution Overview
Problem
Current robotic systems for transferring semiconductor wafers between locations in clean room environments face challenges in achieving optimal swap times while maintaining controlled acceleration, particularly in friction grip or vacuum handling scenarios, leading to inefficiencies and potential collisions.
Innovation Solution
A robotic apparatus with dual end effectors and a control unit that enables simultaneous and synchronized motion along an arc path with constant velocity, allowing for equal and constant velocities of the wafers, thereby optimizing the swap operation and minimizing acceleration-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If robotic systems transfer wafers using friction grip or vacuum handling, then wafers can be securely held, but acceleration must be controlled which increases swap time
Solution Approach 1:
The system dynamically adjusts the motion profile of the robotic apparatus during wafer transfer. By implementing synchronized motion control that allows equal and constant velocities for both wafers along the arc path, the system optimizes transfer speed while maintaining secure handling through controlled acceleration profiles appropriate for friction grip or vacuum handling scenarios.
Solution Approach 2:
The control system modifies motion parameters including velocity, acceleration, and position in real-time during the swap operation. By controlling the robotic apparatus to move along an arc path with equal and constant velocities, the system achieves optimal transfer timing while maintaining parameters within safe limits for the selected handling method (friction grip or vacuum handling).
2Productivity
If robotic systems increase transfer speed to reduce manufacturing time, then productivity improves, but acceleration control becomes more difficult risking collisions
Solution Approach 1:
The control system continuously monitors the positions and velocities of both wafers during the swap operation and adjusts motion commands in real-time. This feedback control ensures that equal and constant velocities are maintained along the arc path, enabling high-speed transfer while preventing collisions through active control of acceleration profiles.
Solution Approach 2:
The system employs dynamic motion control that adapts acceleration and velocity profiles during the transfer operation. By synchronizing the motion of both wafers along the arc path with equal and constant velocities, the system achieves high transfer speeds while maintaining collision avoidance through continuous dynamic adjustment of motion parameters.
3Loss of time
If dual end effectors swap positions along an arc path with equal and constant velocities, then swap time is optimized, but the system complexity increases
Solution Approach 1:
The control system merges the control of both end effectors into a unified synchronized motion control scheme. By treating the swap operation as a coordinated system where both wafers travel along the arc path with equal and constant velocities, the system optimizes swap time while managing complexity through integrated control rather than separate independent controls.
Data Source
AI summary
A robotic apparatus including an arm member configured to pivot about a first axis, a first end effector, a second end effector, a drive unit, and a control unit. The first and second end effectors are pivotably connected to the arm member about a second axis, and each have a surface to receive a workpiece. The drive unit drives the arm member to pivot about the first axis, and to drive the first and second end effectors to pivot about the second axis. The control unit controls the drive unit to move the arm member and the first and second end effectors to perform a swapping operation that includes the first and second end effectors swapping arc positions at opposite ends of an arc of constant radius of curvature such that the workpieces on the first and second end effectors each travel at equal and constant velocities along the arc.