Location

La Jolla, CA

Start Date

1-1-1993 12:00 AM

Description

A method is discussed to use ultrasonic techniques to monitor the reaction bonding of silicon nitride. Reaction bonding takes place in a nitrogen atmosphere heated up to 1390°C. As with many sensors used in hostile environments, it is difficult to design the ultrasonic sensor in a way that provides optimal clarity of the signal. The sensing system has to be designed within physical limitations on access to the furnace and it has to satisfy considerations on the design of a cooling system for the ultrasonic transducer. These limiting factors have been overcome so that ultrasonic signals have been obtained during processing, albeit with a significant noise level. Signal processing techniques have been developed which make it possible to obtain information on changes in phase velocity and attenuation during reaction bonding. The signal processing techniques have the potential to be implemented in real time for the monitoring of the progress of the reaction. This information can then be used for process control feedback.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

12B

Chapter

Chapter 9: Systems, Process Control, and Reliability

Pages

2357-2364

DOI

10.1007/978-1-4615-2848-7_298

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Ultrasonic Monitoring of Reaction Bonding Silicon Nitride

La Jolla, CA

A method is discussed to use ultrasonic techniques to monitor the reaction bonding of silicon nitride. Reaction bonding takes place in a nitrogen atmosphere heated up to 1390°C. As with many sensors used in hostile environments, it is difficult to design the ultrasonic sensor in a way that provides optimal clarity of the signal. The sensing system has to be designed within physical limitations on access to the furnace and it has to satisfy considerations on the design of a cooling system for the ultrasonic transducer. These limiting factors have been overcome so that ultrasonic signals have been obtained during processing, albeit with a significant noise level. Signal processing techniques have been developed which make it possible to obtain information on changes in phase velocity and attenuation during reaction bonding. The signal processing techniques have the potential to be implemented in real time for the monitoring of the progress of the reaction. This information can then be used for process control feedback.