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Title:Charging in Aspect Ratio Dependent Etching
Author(s):Ritz, Eithan
Advisor(s):Ruzic, David N.
Department / Program:Nuclear, Plasma, & Rad Engr
Discipline:Nuclear Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
plasma etching
via twisting
sidewall charging
Abstract:In this work, a novel diagnostic tool was developed in order to provide a measurement technique for sidewall charging in high aspect ratio features exposed to a plasma environment. Currently, high aspect ratio features, holes which are very deep but not very wide, on semiconductor chips are used in order to create the cutting edge computer memory that is used in everyday computers. However, during creation of these features by plasma etching, charge build-up occurs on the sidewalls due to the plasma exposure and it can divert the etch path. The result is that instead of finishing as strictly vertical features, the holes have twists and are therefore defective, as they cannot make the correct electrical connections. In order to study this behavior and its causes, a series of Diagnostics for Etching and Charging (DECs) were created that can simulate high aspect ratio features and record in-situ, real-time current measurements along the etch path. Using these DECs, a complete view of the charging behavior inside the feature was accomplished and its behavior as a function of chamber pressure, RF power and aspect ratio was explored. These experiments were conducted in an Applied Materials oxide-etch chamber which is used in industry for plasma etching of high aspect ratio features. This chamber, donated from the Micron Technology Foundation, was capable of reproducing actual etch conditions used in memory manufacturing but only inert argon gas was used during testing for safety reasons. Using the inductively-coupled plasma source, the DECs were immersed directly into the bulk plasma in order to receive a high flux of current which was subsequently measured. The DECs were able to detect the incoming flux to the top, middle and bottom of the simulated holes in order to determine the behavior of sidewall charging.
Issue Date:2011-05-25
Rights Information:
Copyright 2011 Eithan Ritz
Date Available in IDEALS:2011-05-25
Date Deposited:2011-05

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