| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS1-ThM |
| Session: | Plasma Processing for Disruptive Technologies (NVM, TSV, etc.) |
| Presenter: | J. Ladroue, GREMI - STMicroelectronics, France |
| Authors: | J. Ladroue, GREMI - STMicroelectronics, France M. Boufnichel, STMicroelectronics, France T. Tillocher, GREMI - Polytech Orleans/CNRS, France P. Lefaucheux, GREMI - Polytech Orleans/CNRS, France P. Ranson, GREMI - Polytech Orleans/CNRS, France R. Dussart, GREMI - Polytech Orleans/CNRS, France |
| Correspondent: | Click to Email |
Gallium nitride (GaN) is currently used for light emitter devices due to a large and direct bandgap. Otherwise, GaN physical properties open new prospects in microelectronics manufacturing. By combining a wide bandgap (3.4 eV), strong chemical bonds and a high electron mobility, GaN based devices should operate under higher temperature, higher power and higher frequency than typical silicon devices.
It was shown that wet etching is limited due to inert chemical nature of GaN [1], especially in the c-plan where the etching is generally needed [2]. Therefore, plasma etching is essentially used due to the combination of chemical and physical effects. Chlorine plasmas are used because GaCl3 is the most volatile Ga etching product.
Due to the power density applied to the next generation of power devices, an etched depth as high as 6 to 10 µm is typically required. This could be qualified as deep GaN etching compared to the etched depth needed for light emitter devices which are of the order of few hundreds nanometers.
It was shown that bottom surface defects are linked with dislocations and nanopipes created during the epitaxial growth of GaN [3]. We will show that etched surface presents either pits or columnar defects closely linked with plasma conditions. Mass spectrometry data confirms the importance of ClO species in columnar regimes. We will show that SiCl4 is able to scavenge ClO and allows to provide a smoother surface. SiCl4 can be added in plasma gas or as the etching product of a silicon coverplate. We will also present data showing the influence of SiClx passivation layer on SiO2 hard mask selectivity. Plasma diagnoscics such as optical emission spectroscopy or mass spectrometry will allow us to propose mechanism of formation of this passivation layer.
[1] D. Zhuang and J.H. Edgar, Mat. Sci. and Eng., 48 (2005) 1–46
[2] D. A. Stocker, E. F. Schubert, and J. M. Redwing. Applied Physics Letters, 73 (1998) 2654–2656
[3] J. Ladroue, A. Meritan, M. Boufnichel,P. Lefaucheux, P. Ranson, and R. Dussart, J. Vac. Sci. Technol. A 28, (2010) 1226