AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoP

Paper PS-MoP19
Etching Profile of (Ba,Sr)TiO@sub 3@ Thin Films in a BCl@sub 3@/Cl@sub 2@/Ar Inductively Coupled Plasma

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: G.H. Kim, Chungang University, Korea
Authors: C.I. Kim, Chungang University, Korea
K.T. Kim, Chungang University, Korea
G.H. Kim, Chungang University, Korea
Correspondent: Click to Email
(Ba@sub 1-x@,Sr@sub x@)TiO@sub 3@ (BST) thin film attracts a great interest as a new dielectric material in capacitors for the next generation ultra-large scale integrated dynamic random access memories (ULSI DRAMs), such as giga bit DRAM in the wide range of research institutes to semiconductor industries because of its large dielectric constant, low leakage current and low dielectric loss. In order to realize the higher integration, it is important to minimize the dimension of storage capacitors, simplify the memory cell structure and maintain sufficient accumulated electric charge within a smaller capacitor. Although BST thin films are excellent capacitor dielectric materials for DRAMs, there are several problems such as fine pattern transfer and no plasma induced-damage etc. In order to solve these problems, the etch behavior of BST with BCl@sub 3@/Cl@sub 2@/Ar gas mixtures is performed with inductively coupled plasma (ICP). In this study, inductively coupled plasma etching system was used for BST etching because of its high plasma density, low process pressure and easy control bias power. The etching characteristics of BST thin films were investigated in terms of etch rates and selectivity as a function of Cl@sub 2@/Ar and additive BCl@sub 3@ into Cl@sub 2@/Ar, rf power, dc bias voltage and chamber pressure. The Cl@sub 2@/Ar and additive BCl@sub 3@ into Cl@sub 2@/Ar plasmas were characterized by optical emission spectroscopy (OES), Langmuir probe analysis and quadruple mass spectrometry (QMS). In order to minimize the pattern transfer difference between a dense cell pattern and isolated pattern, we investigated the effects of process parameters (rf power, dc bias, process pressure and residence time) in Cl@sub 2@-based ICP etching. Scanning electron microscopy (SEM) was used to investigate the etching profile.