Ultrasonic Processing of Materials

Ultrasonic monitoring of photoresist processing

A high frequency ultrasonic technique has been developed to monitor photoresist processing in situ during semiconductor manufacturing. Photoresist pre-exposure bake and development have been monitored using the sensor, and the post-exposure bake has been studied as well. The in situ glass transition temperature (Tg ) was determined during the prebake for I-line films down to O.6im as well as fo...

Air-coupled Ultrasonic Testing of Materials

Mapping of Materials Stress with Ultrasonic Tomography

It is _known _that internal stress concentrations can give rise to microcracks which then grow when the str~cture 1s subJected to external forces. It has also been found that the velocity'of sound is altered as ~t propagates through a region of stress. In this paper we discuss a technique called ComputerAsslsted Tomography (~AT) and describe ~n application that provides pictures of stress field...

Ultrasonic Characterization of Advanced Composite Materials

With increased use of composite materials in critical structural applications it is more important than ever to independently assure structural integrity. Complexity of the advanced composite materials including layered and bonded structures represents challenges in developing optimized ultrasonic tests. Traditional ultrasonic NDT methods are inappropriate and often misleading when applied to a...

Ultrasonic Array Imaging Method for Concrete Materials

Because of the need of rapid detection of internal defects and embedded object in concrete structures, a ultrasonic detecting method with linear array transducers is presented here, which is the high-resolution and efficient imaging technique for concrete materials by combining with synthetic aperture focusing technique (SAFT). At first, simulation data of array detection are processed to be am...