Plasma-induced Antenna Effect on the Deep Submicron Devices with Ultrathin Gate Oxides

• Main Authors: Chien, Chao-Hsin, 簡昭欣
• Other Authors: Chang Chun-Yen
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/61147722388644745624

博士 === 國立交通大學 === 電子工程學系 === 85 === In this thesis, the plasma-induced antenna effect on the reliability degradation of devices with ultrathin gate oxides is extensively investigated. This issue is very important in the modern integrated circuit (IC) manufacturing. Many test vehicles are applied and demonstrated as very powerful tools in the evaluation of plasma-induced antenna effect, including charge- to-breakdown (Qbd), initial-electron-trapping-rate (IETR), relative linear trans-conductance reduction and hot-carrier- injection(HCI). A novel method is demonstrated as a effective tool for the evaluation of plasma-induced damage to thin gate oxides. We have found that gate current measured at Vg ( gate voltage ) = Vth (threshold voltage ) under low drain bias ( e.g., 0.1 Volt ) can serve as a good indicator of plasma damage. Since this method is comparable to a routine device parameter measurement, it thus serves as a simple and efficient damage method for studying the plasma charging induced damage. In addition, a helicon wave plasma(HWP) is found to induce lesser degradation of devices than a magnetically-enhanced- reactive-ion-etcher (MERIE) does. A newly discovered resist- related phenomenon, to our best knowledge, is first presented. It is found that during plasma ashing processes, resist actually participates in the plasma charging damage on ultrathin gate oxides. Distinct from electron shading effect, this resist- related damage effect would induce severe degradation for the devices attached to an area-intensive antenna structure. Our results strongly suggest that resist acts not simply as an insulator which can protects devices from plasma charging. Deliberate resist removal by a wet etching process prior to plasma ashing in previous studies will result in a significant underestimation of plasma damage, especially for the devices with ultrathin oxides (< 6nm). A simple model with a combination of the equivalent capacitor circuit and the self-adjustment behavior between the wafer surface and substrate is proposed and shown to successfully explain this resist-related phenomenon. Data in this issue is very valuable to the development of next generation plasma systems and indeed change the intuitive concept about the resist before.