OHT Control Module Prevents Wafer Carrier Collisions

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Solution Overview

Problem

The traditional manual transport of larger wafers in semiconductor manufacturing is inefficient and unsafe due to increased weight, necessitating an automatic transport system that can efficiently move wafer carriers between processing apparatuses without causing system crashes.

Innovation Solution

An automatic handling system utilizing overhead transport vehicles (OHT vehicles) and a control module to manage the movement on surrounding handling tracks, with commands to unload and load wafer carriers based on availability at processing apparatuses, preventing crashes by checking if a wafer carrier device can be unloaded or loaded before proceeding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual transport is used for wafer carriers, then operators can directly push vehicles back and forth, but the system becomes inefficient and unsafe when wafer carrier weight increases to 8 kilograms

Engineering Contradiction:

Improvemanual transport feasibilityVSAvoidtransport safety

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the manual mechanical pushing system with an automated OHT (Overhead Hoist Transport) vehicle system. The OHT vehicles automatically transport wafer carriers along overhead rails between fabrication machine tools, eliminating the need for operators to manually push heavy carriers weighing up to 8 kilograms, thereby ensuring transport safety while maintaining operational efficiency

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The OHT vehicle system operates autonomously to transport wafer carriers without requiring manual intervention. The vehicles self-navigate along the overhead transport rails, automatically delivering carriers to designated fabrication machine tools, which eliminates safety concerns associated with manual handling of heavy carriers

Inventive Principle:

Principle #25Self-service

2Device complexity

If traditional manual transport is used, then simple operations are possible, but handling time increases and efficiency decreases

Engineering Contradiction:

Improvetransport system simplicityVSAvoidwafer handling efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent replaces simple manual transport operations with an automated OHT vehicle system that operates along overhead rails. This substitution increases wafer handling efficiency by enabling continuous, high-speed transport of wafer carriers between fabrication machine tools, eliminating the time-consuming nature of manual transport operations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The OHT vehicle system enables continuous transport operations along the overhead rails, with multiple vehicles operating simultaneously to move wafer carriers between fabrication machine tools without interruption. This continuous operation significantly increases productivity compared to discrete manual transport operations

Inventive Principle:

Principle #20Continuity of useful action

3Speed

If OHT vehicles operate without checking availability, then transport speed is high, but system crashes occur when wafer carriers cannot be unloaded

Engineering Contradiction:

Improvetransport speedVSAvoidsystem crash prevention

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent implements preliminary checking of wafer carrier availability at the destination fabrication machine tool before the OHT vehicle begins its transport operation. The control system queries whether the target apparatus can receive and unload the wafer carrier, and only authorizes transport if the destination is ready, thereby preventing system crashes while maintaining efficient transport speed

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system implements feedback mechanisms that continuously monitor the status of fabrication machine tools and OHT vehicles. Before authorizing transport, the system receives feedback regarding the availability and readiness of the destination apparatus, and uses this feedback to control whether the OHT vehicle should proceed with the transport operation, preventing crashes while maintaining high transport speed

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8831765B2Method for operating an automatic handling system applied to many wafer processing apparatuses

Publication Date: 2014.09.09 MICRON TECHNOLOGY INC

AI summary

The instant disclosure provides a method for operating an automatic handling system applied to many wafer processing apparatuses. When a OHT (Overhead Hoist Transport) vehicle is moved to one of the wafer processing apparatuses, the OHT vehicle can ask a OHT control module whether a wafer carrier device can be unloaded from the OHT vehicle onto the wafer processing apparatus. There are two judgment methods as follows: (1) If there is another wafer carrier device already disposed on the wafer processing apparatus, the OHT control module will inform the OHT vehicle that the wafer carrier device cannot be unloaded from the OHT vehicle onto the wafer processing apparatus; (2) If there is no any wafer carrier device disposed on the wafer processing apparatus, the OHT control module will inform the OHT vehicle that the wafer carrier device can be unloaded from the OHT vehicle onto the wafer processing apparatus.