AVS 66th International Symposium & Exhibition
    Thin Films Division Tuesday Sessions
       Session TF+EM+MI-TuM

Paper TF+EM+MI-TuM11
Oxidation Studies of Silicon Germanium (SiGe) using In-Situ Steam Generated (ISSG) and Plasma Enhanced Atomic Layer Deposited (PEALD) Oxides

Tuesday, October 22, 2019, 11:20 am, Room A122-123

Session: Thin Films for Microelectronics, Photonics, and Optoelectronic Applications
Presenter: Yi Song, IBM Research Division, Albany, NY
Authors: Y. Song, IBM Research Division, Albany, NY
S. Siddiqui, IBM Research Division, Albany, NY
C. Durfee, IBM Research Division, Albany, NY
A. Pana, IBM Research Division, Albany, NY
J. Li, IBM Research Division, Albany, NY
M. Belyansky, IBM Research Division, Albany, NY
S. Naczas, IBM Research Division, Albany, NY
E.P. Stuckert, IBM Research Division, Albany, NY
L. Jiang, IBM Research Division, Albany, NY
J. Demarest, IBM Research Division, Albany, NY
V. Basker, IBM Research Division, Albany, NY
D. Guo, IBM Research Division, Albany, NY
H. Bu, IBM Research Division, Albany, NY
Correspondent: Click to Email
SiGe is a versatile material for the semiconductor industry for sub-7 nm node technology development; it can be used as a high mobility channel material in FinFET, and as multiple sacrificial layers to form channel regions in gate all around (GAA) nanosheet device architecture. Understanding SiGe film oxidation is important for matching oxidation rates between SiGe layers with different Ge% in nanosheet applications [1]. In this paper, a study of ISSG (800 oC) and PEALD (room temperature to 300 oC) oxidation processes is performed on blanket Si1-xGex films ranging from x = 0.25 to 0.80. We establish the boundaries of three distinct regions of oxidation behavior for the ISSG process (Region I: 0 < x < 0.5, Region II: 0.5 < x < 0.67, and Region III: x > 0.67). Historically, low Ge oxidation has been extensively studied [2-4]. Here, we show for Region I, the ISSG oxidation rate is very small (1.7 nm of oxide growth in 5 sec). The oxidation rate rapidly increases in Region II as x increases, where it reaches a maximum (13.8 nm in 5 sec) at the Region II/Region III boundary, then abruptly drops in Region III as x increases due to complete sublimation of Ge (see Figure 1). The abrupt increase in the ISSG oxidation rate between Regions I and II makes it difficult to match oxide thicknesses for the wide range of Ge% utilized by nanosheet device architecture. Therefore, we studied a lower temperature oxidation process (PEALD) which has a lower oxidation rate. We found that PEALD oxidation rates are unchanged across the Region I/II boundary, even for higher temperatures up to 300 oC as shown in Figure 2. This enables oxide thickness matching for a wide range of Ge%. These results are applicable to the development of various nanotechnologies such as nanosheet and high mobility channel FinFET devices.