Megasonic jet cleaner apparatus

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT As seen in FIG.
1, the nozzle assembly 10 (to be described) is positioned to develop a fluid jet 12 for projection in a direction preferably perpendicular to the surface 14 of wafer 16.
The transducer 10 is supported on a flange 13 to a support structure 15 by screws 13a.
A wafer support apparatus 18 includes a vacuum-type chuck 17 supported on a shaft 19 for holding and rotating the wafer 16 as it faces the jet 12.
Assuming a fluid jet in ribbon form of 2" (5.
08 cm) in width, a 4" (10.
15 cm) wafer 16 can be cleaned by the fluid jet in one rotaton of the wafer with the ribbon of the jet positioned along a radius of the wafer.
The fluid jet 12 has energy velocity developed from the pressure of the supply source of the fluid via inlet tube 28.
Typically a suitable cleansing fluid such as a solution of water, hydrogen peroxide and chlorine in the ratio of 4:1:1 by volume is supplied from a source (not shown) under pressure and conducted to the upstream portion of the nozzle at which location the fluid is modulated with ultrasonic energy.
The jet stream 12 that is developed by the nozzle when applied to the wafer surface 14 cleanses the surface of the wafer 16 with the combination of the cleansing action of the pressurized cleansing fluid modulated by megasonic energy.
The theory of the effect of the ultrasonic energy is believed to be based on the very rapid movement of the fluid molecules which causes an acceleration in the order of 100,000 g generated by a megasonic transducer output of about 7.
5 watts per square centimeter.
The ultrasonic modulation of the fluid molecules in combinatin with the nozzle pressure of the fluid stream loosens the particles from the surface of the wafer and then washes them away to prevent thereby the particles from being redeposited on the cleansed surface.
The nozzle 10 provides a means for focusing megasonic energy carried in a stream of cleansing fluid into a small area.
This nozzle focusing effect increases the power density on the area being cleaned as compared to a megasonic transducer without a nozzle