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RF Sputtering Technique

IP.com Disclosure Number: IPCOM000082559D
Original Publication Date: 1974-Dec-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Greiner, JH: AUTHOR [+2]

Abstract

In conventional RF sputtering, an RF sinusoidal voltage is applied to the sputtering cathode, which produces a voltage waveform at the cathode surface having a negative bias as shown in Fig. 1. When the cathode voltage is positive, the electrons are collected at the cathode. When the cathode voltage is negative, positive ions bombard it to cause sputtering of the cathode material. As a result of the applied voltage waveform, the ions are accelerated with varying voltages and thus the bombarding ions have varying energies.

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RF Sputtering Technique

In conventional RF sputtering, an RF sinusoidal voltage is applied to the sputtering cathode, which produces a voltage waveform at the cathode surface having a negative bias as shown in Fig. 1. When the cathode voltage is positive, the electrons are collected at the cathode. When the cathode voltage is negative, positive ions bombard it to cause sputtering of the cathode material. As a result of the applied voltage waveform, the ions are accelerated with varying voltages and thus the bombarding ions have varying energies.

In order to increase sputtering rates without increasing adverse cathode and anode surface effects, it is proposed to apply the voltage waveform shown in Fig. 2 to the cathode. When this is done, electrons are collected at the cathode when the cathode has a positive voltage, while positive ions bombard the cathode surface when the cathode has a negative voltage. However, when the waveform of Fig. 2 is used, the ions are accelerated from the plasma across a constant potential. There is an increased sputtering for the same peak voltage as the sinusoid waveform, since the average voltage is close to the peak voltage (Fig.
2).

Additionally, the waveform of Fig. 2 reduces the possibility of cathode and anode surface damage (heating and structural effects) by electrons and ions for equal sputtering rates, as compared to Fig. 1, since the proposed waveform will have lower peak voltages and reduced input power. Also, use of the p...