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Title: Understanding the Mechanism of Electronic Defect Suppression Enabled by Nonidealities in Atomic Layer Deposition

Abstract

Silicon germanium (SiGe) is a multifunctional material considered for quantum computing, neuromorphic devices, and CMOS transistors. However, implementation of SiGe in nanoscale electronic devices necessitates suppression of surface states dominating the electronic properties. The absence of a stable and passive surface oxide for SiGe results in the formation of charge traps at the SiGe-oxide interface induced by GeOx. In an ideal ALD process in which oxide is grown layer by layer, the GeOx formation should be prevented with selective surface oxidation (i.e., formation of an SiOx interface) by controlling the oxidant dose in the first few ALD cycles of the oxide deposition on SiGe. However, in a real ALD process, the interface evolves during the entire ALD oxide deposition due to diffusion of reactant species through the gate oxide. In this work, this diffusion process in nonideal ALD is investigated and exploited: the diffusion through the oxide during ALD is utilized to passivate the interfacial defects by employing ozone as a secondary oxidant. Periodic ozone exposure during gate oxide ALD on SiGe is shown to reduce the integrated trap density (Dit) across the band gap by nearly 1 order of magnitude in Al2O3 (<6 × 1010 cm-2) and in HfO2more » (<3.9 × 1011 cm-2) by forming a SiOx-rich interface on SiGe. Depletion of Ge from the interfacial layer (IL) by enhancement of volatile GeOx formation and consequent desorption from the SiGe with ozone insertion during the ALD growth process is confirmed by electron energy loss spectroscopy (STEM-EELS) and hypothesized to be the mechanism for reduction of the interfacial defects. In this work, the nanoscale mechanism for defect suppression at the SiGe-oxide interface is demonstrated, which is engineering of diffusion species in the ALD process due to facile diffusion of reactant species in nonideal ALD.« less

Authors:
ORCiD logo [1];  [2];  [2]; ORCiD logo [3];  [1];  [4];  [5];  [1];  [3]; ORCiD logo [1]
  1. Univ. of California, San Diego, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  3. Stanford Univ., CA (United States)
  4. Univ. of California, Irvine, CA (United States)
  5. Univ. of California, San Diego, CA (United States). California Inst. for Telecommunications and Information Technology
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
OSTI Identifier:
1605266
Grant/Contract Number:  
AC02-05CH11231; ECCS-1542148
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 142; Journal Issue: 1; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Oxides; Interfaces; Deposition; Atomic layer deposition; Defects

Citation Formats

Kavrik, Mahmut Sami, Bostwick, Aaron, Rotenberg, Eli, Tang, Kechao, Thomson, Emily, Aoki, Toshihiro, Fruhberger, Bernd, Taur, Yuan, McIntyre, Paul C., and Kummel, Andrew C.. Understanding the Mechanism of Electronic Defect Suppression Enabled by Nonidealities in Atomic Layer Deposition. United States: N. p., 2019. Web. https://doi.org/10.1021/jacs.9b06640.
Kavrik, Mahmut Sami, Bostwick, Aaron, Rotenberg, Eli, Tang, Kechao, Thomson, Emily, Aoki, Toshihiro, Fruhberger, Bernd, Taur, Yuan, McIntyre, Paul C., & Kummel, Andrew C.. Understanding the Mechanism of Electronic Defect Suppression Enabled by Nonidealities in Atomic Layer Deposition. United States. https://doi.org/10.1021/jacs.9b06640
Kavrik, Mahmut Sami, Bostwick, Aaron, Rotenberg, Eli, Tang, Kechao, Thomson, Emily, Aoki, Toshihiro, Fruhberger, Bernd, Taur, Yuan, McIntyre, Paul C., and Kummel, Andrew C.. Thu . "Understanding the Mechanism of Electronic Defect Suppression Enabled by Nonidealities in Atomic Layer Deposition". United States. https://doi.org/10.1021/jacs.9b06640. https://www.osti.gov/servlets/purl/1605266.
@article{osti_1605266,
title = {Understanding the Mechanism of Electronic Defect Suppression Enabled by Nonidealities in Atomic Layer Deposition},
author = {Kavrik, Mahmut Sami and Bostwick, Aaron and Rotenberg, Eli and Tang, Kechao and Thomson, Emily and Aoki, Toshihiro and Fruhberger, Bernd and Taur, Yuan and McIntyre, Paul C. and Kummel, Andrew C.},
abstractNote = {Silicon germanium (SiGe) is a multifunctional material considered for quantum computing, neuromorphic devices, and CMOS transistors. However, implementation of SiGe in nanoscale electronic devices necessitates suppression of surface states dominating the electronic properties. The absence of a stable and passive surface oxide for SiGe results in the formation of charge traps at the SiGe-oxide interface induced by GeOx. In an ideal ALD process in which oxide is grown layer by layer, the GeOx formation should be prevented with selective surface oxidation (i.e., formation of an SiOx interface) by controlling the oxidant dose in the first few ALD cycles of the oxide deposition on SiGe. However, in a real ALD process, the interface evolves during the entire ALD oxide deposition due to diffusion of reactant species through the gate oxide. In this work, this diffusion process in nonideal ALD is investigated and exploited: the diffusion through the oxide during ALD is utilized to passivate the interfacial defects by employing ozone as a secondary oxidant. Periodic ozone exposure during gate oxide ALD on SiGe is shown to reduce the integrated trap density (Dit) across the band gap by nearly 1 order of magnitude in Al2O3 (<6 × 1010 cm-2) and in HfO2 (<3.9 × 1011 cm-2) by forming a SiOx-rich interface on SiGe. Depletion of Ge from the interfacial layer (IL) by enhancement of volatile GeOx formation and consequent desorption from the SiGe with ozone insertion during the ALD growth process is confirmed by electron energy loss spectroscopy (STEM-EELS) and hypothesized to be the mechanism for reduction of the interfacial defects. In this work, the nanoscale mechanism for defect suppression at the SiGe-oxide interface is demonstrated, which is engineering of diffusion species in the ALD process due to facile diffusion of reactant species in nonideal ALD.},
doi = {10.1021/jacs.9b06640},
journal = {Journal of the American Chemical Society},
number = 1,
volume = 142,
place = {United States},
year = {2019},
month = {11}
}

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