Measurements of electron density and electron temperature with plasma absorption probe and its application to deposited plasmas

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Recently, high performance LSI electronic devices has been studied to improve capability, calculation speed and power consumption. To achieve this issue, microfabrication with a feature size less than 〜100 nm and low-k materials for improvement of signal delay at distribution lines have been developed. Plasma processing has been widely used for the microfabrication and the low-k film formation, however there are still various problems to be solved. Understanding of plasma properties and precise control of the plasma suitable for desired process have been requred.In this work, plasma absorption probes which enable us to measure electron density even under soiled conditions of insulated polymer deposition were improved to measure electron temperature of important parameters to characterize the plasma. We also applied the probe to diagnostics of CVD plasmas for the low-k film formation, and fundamental data to improve the materials process were obtained.A sheath around the probe antenna a … More ffects on an absorption frequency measured with the probe, and sheath thickness is given by a several times of Debye length as a function of electron density and electron temperature. Therefore, when absorption frequencies are measured two surface wave absorption probes having different dependence on the sheath thickness, both of electron density and electron temperature can be simultaneously obtained. An antenna diameter of the probe significantly affected on the relation between the electron density and electron temperature, and the electron density satisfying the measured absorption frequency became independent of electron temperature as the antenna diameter increased. The different temperature dependence of the satisfying density between the two probes was preferable to accurately determine the density and the temperature. Therefore, the probes with much different antenna diameter were preferable to achieve accurate measurements. Finally, electron density and electron was available with the almost same accuracy of a conventional Langmuir probe.The probe revealed the following characteristics of a narrow gap CVD plasma system for low-k film deposition. (1)An electron density as well as its radial profile significantly depended on conditions such as discharge powers and operating pressures, and a correlation between radial profiles of the electron density and a deposition rate over a 12-inch-diam. silicon wafer. (2)An electron temperature decreased with an increase in the total operating pressure as well as a fraction of parent material gases. Xe addition was also effective for reduction of the electron temperature. However significant radial profile was not clearly observed.As derivative results, the probe system was also applied to other plasma systems for materials processing, and useful for their plasma diagnostics. Less