On ion energy control of dual frequency capacitive coupled plasma for high aspect ratio process

Abstract

High aspect ratio contact (HARC) etching technology is also important at the upcoming semiconductor process. To achieve HARC process, high ion bombarding energy on a substrate is essential. Then we research the ion energy controlling at the plasma system which is very similar as industrial process. In the semiconductor industry, dual frequency concept and pulsed plasma concept are used widely. Because the dual-frequency CCP have independent control property [29, 30] and the pulsed plasma can relieve charging problem on the substrate. [32] We set a dual frequency CCP system using our large area CCP chamber which is used above. We apply two dual-frequency settings. (High frequency / low frequency) One is 13.56 MHz / 2 MHz and the other is 40 MHz / 3 MHz. A pulse source is connected with LF generator to trigger pulsed LF power. We measure bias voltage data from the point between the matcher and the chamber with 1000 : 1 probe and oscilloscope. The bias voltage is heavily relate with the ion energy. After bias voltage measurement, we use an impedance measurement system which is developed by Plasmart. [35] From the innovative apparatus, we measure real and imaginary impedance of each signal (high frequency signal and low frequency signal) From these data, we investigate the role of the each signal in our LF pulsed dual frequency plasma at various pressure and duty ratio of the pulse triggering.