Measurement of residual particles by high-intensity aerial ultrasonic nerves

When high-intensity aerial ultrasonic waves (with a frequency of approximat ely 20-50 kHz) are applied to drops of liquid adhering to the surface of an object, the drops instantaneously atomize and peel off. from the object an d scatter in the ail: II extremely strong sound waves (approximately 170 dB (sound pressure level; SPL)) art: applied, it is also possible to cause the solid particles remaining on the surface of an object to peel off and scat ter in the air. In this report, we describe a study in which we investigate d a new method that uses the above-mentioned effects produced by aerial ult rasonic waves to quantitatively evaluate the cleanness, with regard to the particles remaining on their surface, of semiconductor manufacturing jigs t hat have been precision-cleaned. This method has various features, includin g (1) it can be conducted without touching the target object, (2) it can be used on a specific area of the object, (3) it does not depend on the shape of the object, and (3) its measurements can be easily carried out.