Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Low Frequency Ultrasonic Jet for Enhanced Plating and Etching

IP.com Disclosure Number: IPCOM000034385D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Von Gutfeld, RJ: AUTHOR [+2]

Abstract

High frequency ultrasonic waves can be used to enhance the morphology of electroplated deposits of gold and copper. These waves can be produced by a piezoelectric transducer at 7.5 MHz which is directed into a small jet stream of the electrolyte. However, cavitation is frequency dependent and the energy for cavitation to occur rises steeply above about 100 KHz. Also, for lower frequencies, the limiting current density is higher. Thus, while there is some advantage to the acoustic jet, the present article provides a scheme that allows a much lower frequency to be directed into the jet to achieve higher plating and etching rates afforded by the use of frequencies for which piezoelectric methods become very difficult, if not impossible.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 64% of the total text.

Page 1 of 2

Low Frequency Ultrasonic Jet for Enhanced Plating and Etching

High frequency ultrasonic waves can be used to enhance the morphology of electroplated deposits of gold and copper. These waves can be produced by a piezoelectric transducer at 7.5 MHz which is directed into a small jet stream of the electrolyte. However, cavitation is frequency dependent and the energy for cavitation to occur rises steeply above about 100 KHz. Also, for lower frequencies, the limiting current density is higher. Thus, while there is some advantage to the acoustic jet, the present article provides a scheme that allows a much lower frequency to be directed into the jet to achieve higher plating and etching rates afforded by the use of frequencies for which piezoelectric methods become very difficult, if not impossible. To generate these lower frequency waves, phase matching of coils 10 spaced along a magnetic rod 12 (nickel, cobalt, iron) is used, as shown in Fig. 1. A phase matched current supply 11 is connected to coils 10. The rod enters pressurized electrolyte cell 13 and is insulated with a TEFLON* spray to prevent interaction between it and the

(Image Omitted)

electrolyte 14. The rod is placed through the nozzle 16 (Fig. 2) with the extensional waves radiating into the jet 18. Once the acoustic waves are in the jet they become trapped due to the boundary conditions at the jet-air interface. The jet acts as a waveguide and the sound radiates from the rod and is confined in the near...