Substrate Conveying Robot Joint Control for Wafer Alignment
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Solution Overview
Problem
Conventional substrate conveying robots face misalignment issues during the transfer of wafers from an aligner to a stage, requiring precise alignment on the stage to compensate for potential deviations.
Innovation Solution
A substrate conveying robot with an articulated robot arm and a drive mechanism that includes a drive source and a driving force transmission unit, controlled by a robot control unit to adjust the arm's joints, ensuring accurate positioning by raising or lowering the hand and displacing joints in specific intervals to maintain precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the hand moves the substrate from the aligner to the stage in a conventional manner, then the conveying speed is maintained, but the positioning accuracy deteriorates causing misalignment
Solution Approach 1:
The robot control unit performs preliminary actions by raising the hand to an upper position above the target position before moving to the target position, and by displacing joints in one direction in advance. This preliminary positioning action ensures that when the hand reaches the target position, the substrate is already accurately positioned, eliminating misalignment without requiring speed reduction
Solution Approach 2:
The system dynamically adjusts the hand's vertical position (raising to upper position) and joint configurations during the conveying process. By making the positioning process dynamic rather than static, the system can maintain high conveying speed while achieving accurate positioning through real-time adjustments of hand position and joint angles
2Measurement precision
If precise alignment on the stage is performed to compensate for misalignment, then the positioning accuracy is improved, but the processing time increases
Solution Approach 1:
Alignment is performed preliminarily during the conveying process itself rather than as a separate compensating step. By raising the hand to the upper position and displacing joints in one direction before reaching the target, the substrate is pre-aligned during transfer, eliminating the need for time-consuming post-transfer alignment adjustments on the stage
Data Source
AI summary
A robot control unit for a substrate conveying robot raises a hand from a first lower position below a first target position at which the hand picks up a substrate to a first upper position above the first target position, and displaces at least one of a plurality of joints in one direction, in a first interval from the first lower position to a first intermediate position between the first lower position and the first target position.