| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Wednesday Sessions |
| Session TF+EM+MI-WeM |
| Session: | Thin Films for Microelectronics |
| Presenter: | Xin Meng, University of Texas at Dallas |
| Authors: | X. Meng, University of Texas at Dallas H.S. Kim, University of Texas at Dallas A.T. Lucero, University of Texas at Dallas J.S. Lee, University of Texas at Dallas Y.-C. Byun, University of Texas at Dallas J. Kim, University of Texas at Dallas B.K. Hwang, Dow Chemical X. Zhou, Dow Chemical M. Telgenhoff, Dow Chemical J. Young, Dow Chemical |
| Correspondent: | Click to Email |
Plasma-enhanced ALD (PEALD) has become an attractive method of depositing silicon nitride (SiNx) due to its ability to grow high-quality films at low temperatures (≤400°C) for various applications [1]. The use of a chlorosilane precursor, is considered a suitable approach for high-volume manufacturing in the semiconductor industry. Chlorosilane precursors can be applicable to either PEALD SiNx or thermal ALD SiNx process. In this work, we have investigated the growth of SiNx thin films using a novel chlorosilane precursor pentachlorodisilane (PCDS, HSi2Cl5)(synthesized by Dow Corning Corporation, vapor pressure ~10 mmHg at 20 °C) in comparison with hexachlorodisilane (HCDS, Si2Cl6). A home-made PEALD system equipped with a hollow cathode plasma source (Meaglow Ltd.) was used in this study.
We analyzed the growth per cycle (GPC) and refractive index (R.I.) as a function of the silicon precursor or plasma exposure time, deposition temperature and plasma power. We also investigated the wet etch rate (WER) in dilute hydrochloric acid as a function of the hydrogen content determined by Fourier Transform Infrared Spectrometry (FTIR), and film density determined by X-ray reflectivity (XRR). Using an N2/NH3 plasma, saturated growth behavior was demonstrated by PCDS and HCDS with a precursor exposure of ~3×105 L. GPC was nearly independent of both deposition temperature and RF power, within the investigated regime. Compared to HCDS, PCDS demonstrated approximately 20–30% higher GPC under the same process condition while maintaining comparable WER.
In addition, it was found that the films with higher hydrogen content had a general tendency to have a higher WER while the films with a higher density or higher R.I. tended to have a lower WER. The oxygen content of the bulk SiNx films determined by ex-situ X-ray photoelectron spectroscopy (XPS) was approximately 3~5 at. % and didn’t have a direct correlation with the WER. Furthermore, MIM capacitors (Al/SiNx/degenerated Si) using PEALD SiNx films grown with PCDS were fabricated. The capacitors exhibited excellent electrical properties, such as a low leakage current density of 10-9–10-10 A/cm2 at 3 MV/cm, and a high breakdown electric field ~13 MV/cm.
[1]. Meng, X.; Byun, Y.-C.; Kim, H.; Lee, J.; Lucero, A.; Cheng, L.; Kim, J., “Atomic Layer Deposition of Silicon Nitride Thin Films: A Review of Recent Progress, Challenges, and Outlooks,” Materials, 9 (12), 1007 (2016)