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Title: Morphological instability of Ag films caused by phase transition in the underlying Ta barrier layer

Abstract

Wide-bandgap (WBG) semiconductor technologies are maturing and may provide increased device performance in many fields of applications, such as high-temperature electronics. However, there are still issues regarding the stability and reliability of WBG devices. Of particular importance is the high-temperature stability of interconnects for electronic systems based on WBG-semiconductors. For metallization without proper encapsulation, morphological degradation can occur at elevated temperatures. Sandwiching Ag films between Ta and/or TaN layers in this study is found to be electrically and morphologically stabilize the Ag metallization up to 800 °C, compared to 600 °C for uncapped films. However, the barrier layer plays a key role and TaN is found to be superior to Ta, resulting in the best achieved stability, whereas the difference between Ta and TaN caps is negligible. The β-to-α phase transition in the underlying Ta barrier layer is identified as the major cause responsible for the morphological instability observed above 600 °C. It is shown that this phase transition can be avoided using a stacked Ta/TaN barrier.

Authors:
; ; ; ; ;  [1]
  1. Solid State Electronics, The Ångström Laboratory, Uppsala University, P.O. Box 534, SE-75121 (Sweden)
Publication Date:
OSTI Identifier:
22310867
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DEPLETION LAYER; ENCAPSULATION; FILMS; INSTABILITY; PHASE TRANSFORMATIONS; RELIABILITY; SEMICONDUCTOR MATERIALS; SILVER; STABILITY; TANTALUM; TANTALUM NITRIDES

Citation Formats

Mardani, Shabnam, E-mail: shabnam.mardani@angstrom.uu.se, Vallin, Örjan, Wätjen, Jörn Timo, Norström, Hans, Olsson, Jörgen, and Zhang, Shi-Li, E-mail: shili.zhang@angstrom.uu.se. Morphological instability of Ag films caused by phase transition in the underlying Ta barrier layer. United States: N. p., 2014. Web. doi:10.1063/1.4893768.
Mardani, Shabnam, E-mail: shabnam.mardani@angstrom.uu.se, Vallin, Örjan, Wätjen, Jörn Timo, Norström, Hans, Olsson, Jörgen, & Zhang, Shi-Li, E-mail: shili.zhang@angstrom.uu.se. Morphological instability of Ag films caused by phase transition in the underlying Ta barrier layer. United States. doi:10.1063/1.4893768.
Mardani, Shabnam, E-mail: shabnam.mardani@angstrom.uu.se, Vallin, Örjan, Wätjen, Jörn Timo, Norström, Hans, Olsson, Jörgen, and Zhang, Shi-Li, E-mail: shili.zhang@angstrom.uu.se. Mon . "Morphological instability of Ag films caused by phase transition in the underlying Ta barrier layer". United States. doi:10.1063/1.4893768.
@article{osti_22310867,
title = {Morphological instability of Ag films caused by phase transition in the underlying Ta barrier layer},
author = {Mardani, Shabnam, E-mail: shabnam.mardani@angstrom.uu.se and Vallin, Örjan and Wätjen, Jörn Timo and Norström, Hans and Olsson, Jörgen and Zhang, Shi-Li, E-mail: shili.zhang@angstrom.uu.se},
abstractNote = {Wide-bandgap (WBG) semiconductor technologies are maturing and may provide increased device performance in many fields of applications, such as high-temperature electronics. However, there are still issues regarding the stability and reliability of WBG devices. Of particular importance is the high-temperature stability of interconnects for electronic systems based on WBG-semiconductors. For metallization without proper encapsulation, morphological degradation can occur at elevated temperatures. Sandwiching Ag films between Ta and/or TaN layers in this study is found to be electrically and morphologically stabilize the Ag metallization up to 800 °C, compared to 600 °C for uncapped films. However, the barrier layer plays a key role and TaN is found to be superior to Ta, resulting in the best achieved stability, whereas the difference between Ta and TaN caps is negligible. The β-to-α phase transition in the underlying Ta barrier layer is identified as the major cause responsible for the morphological instability observed above 600 °C. It is shown that this phase transition can be avoided using a stacked Ta/TaN barrier.},
doi = {10.1063/1.4893768},
journal = {Applied Physics Letters},
number = 7,
volume = 105,
place = {United States},
year = {Mon Aug 18 00:00:00 EDT 2014},
month = {Mon Aug 18 00:00:00 EDT 2014}
}