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Method for closed-loop stability control for robotic wafer handling systems using piezoelectric accelerometers

IP.com Disclosure Number: IPCOM000085001D
Publication Date: 2005-Mar-02
Document File: 4 page(s) / 99K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for closed-loop stability control for robotic wafer handling systems using piezoelectric accelerometers. Benefits include improved system functionality and performance with potential for better product yields.

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Method for closed-loop stability control for robotic wafer handling systems using piezoelectric accelerometers

Disclosed is a method for closed-loop stability control for robotic wafer handling systems using piezoelectric accelerometers.  Benefits include improved system functionality and performance with potential for better product yields.   

Background

              Piezoelectric crystals are widely used in robotic handling systems and other industrial equipment applications.  Ceramic crystals are used as accelerometers in high temperature/low pressure conditions to sense system micro vibrations. Similar vibration sensing systems are utilized in the avionics field for wing stability measurements.

              Due to variations in wafer handling robotic systems, such as machining, tensioning, and installation, significant mismatches occur in control software when adjusting and optimizing movements.  These factors can result in large tangential movement variations at the wafer surface even for the same mechanical design.  For example, a system can have drifts in system error tracking over its effective burn-in/wear-in cycle of up to 4X.  Some wafer placement envelopes could have very tight tolerances, much less than normal system drift, depending on the equipment design constraints.

Therefore, a result of movement variation is wafer misplacement and breakage, which decreases yield and results in revenue loss from machine unavailability.

Changes or modifications in robotic system control servos typically require the supervision of engineers. Changes are made iteratively through an intensive testing process. When a new control software version is released to the affected system, the field system must be taken down and retrofitted, thus costing the customer...