Oblique Transfer Arm for Semiconductor Substrate Positioning
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Solution Overview
Problem
High-speed and high-accuracy substrate transfer in semiconductor manufacturing is hindered by inertial forces causing positional displacement and nonuniform treatment due to support members larger than the substrate, leading to issues like nonuniform film thickness, exposure, and heating problems.
Innovation Solution
A substrate transfer method using a transfer arm that lowers obliquely onto a mounting means after detection by a mounting portion detector, with optional support pin and jump-up detection mechanisms to correct slippage and ensure precise positioning, and a control system to manage the transfer process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transfer arm moves the substrate at high speed to improve throughput, then productivity increases, but inertial forces cause substrate slippage and positional displacement degrading treatment accuracy
Solution Approach 1:
The transfer arm's lowering direction is dynamically adjusted from vertical to oblique based on the substrate's position and the mounting means' location. This dynamic adjustment allows the transfer arm to counteract inertial forces during high-speed movement, preventing substrate slippage while maintaining treatment accuracy. The oblique lowering path is calculated to compensate for the substrate's tendency to displace under acceleration.
Solution Approach 2:
The lowering direction parameter of the transfer arm is changed from vertical to oblique. This parameter change modifies the force application vector during substrate delivery, allowing the system to maintain control over the substrate's position even at high transfer speeds. The oblique angle is optimized to balance between preventing slippage and ensuring accurate placement on the mounting means.
2Reliability
If the support member is made larger than the substrate to accommodate dimensional errors, then reliability of substrate support improves, but inertial forces during high-speed transfer cause substrate slippage and nonuniform treatment
Solution Approach 1:
Instead of uniformly supporting the entire substrate with a large support member, the system provides localized support at the substrate's edges or specific contact points. This localized support approach maintains substrate stability during transfer while minimizing the support member's size and surface area, thereby reducing inertial forces that cause slippage and nonuniform treatment.
Solution Approach 2:
The support member's contact points with the substrate are dynamically adjusted during the transfer process. During high-speed movement, contact is maintained at optimal locations to prevent slippage, while during stationary treatment phases, support is minimized to avoid interfering with treatment uniformity. This dynamic support adjustment resolves the contradiction between reliability and precision.
Data Source
AI summary
A substrate transfer method of delivering a substrate transferred by a transfer arm to a mounting unit and associated apparatus. The method includes moving the transfer arm to a position above the mounting unit, and, when delivering the substrate onto the mounting unit, detecting a mounting portion of the mounting unit by a mounting portion detector having a light emitting element and a light receiving element provided at opposite positions across a center point of the transfer arm on a bottom surface of the transfer arm, and then lowering the transfer arm in an oblique direction to mount the substrate on the mounting unit.