| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | J. Cao, Nagoya University, Japan |
| Authors: | J. Cao, Nagoya University, Japan Y. Lu, Nagoya University, Japan R. Kometani, Nagoya University, Japan J. Park, Nagoya University, Japan K. Ishikawa, Nagoya University, Japan K. Takeda, Nagoya University, Japan H. Kondo, Nagoya University, Japan M. Sekine, Nagoya University, Japan M. Hori, Nagoya University, Japan |
| Correspondent: | Click to Email |
Gallium nitride and related alloys have been expanding their applications for next-generation optoelectronics such as HEMTs or white LEDs. Plasma etching processes are necessary especially for ternary compounds such as AlGaN and InGaN. To control precisely profiles at nano-scale and to reduce plasma-induced damages, which influencing the device performance,1-3 the mechanism of reaction of ions and radicals in plasma with surfaces should be clarified. In this research, we investigated the etching mechanism of AlGaN in chlorine plasma with focusing on surface stoichiometric composition.
Samples were Al0.32GaN, Al0.47GaN and GaN epitaxial films grown on Si substrate. Photolithographic patterning of UV photoresist was conducted. After chemical cleaning, an inductive coupled plasma etcher was used; the typical condition is antenna power of 200 W, bias RF power of 0 - 120 W, Cl2/Ar mixture gas flow rate of 30 sccm at 1 Pa. The samples were chucked electrostatically on the stage kept at room temperature. X-ray photoelectron spectroscopy (XPS) was used for stoichiometric composition analysis.
When changing the ratio of Cl2/(Cl2+Ar) from 0 to 100%, the etch rate of GaN and AlGaN was increasing with the Cl2 ratio. The etch rate in all cases saturated as increased the Cl2 flow ratio above 40%. Order of the etch rate among the films were Al0.47GaN < Al0.32GaN < GaN, which could be explained by their sputtering threshold energies for Al-N of 11.52 eV and Ga-N of 8.92 eV.4 Since the etching products such as AlClx have high volatility compared with GaCly, a layer consisting of low Al-to-Ga ratio was possibly formed on the AlGaN surface. We will discuss the effects of plasma parameters on both etching profiles and surface stoichiometry in order to elucidate comprehensively understanding of the etching mechanism.
This work was supported by the Knowledge Cluster Initiative (Second Stage), MEXT, Japan. We would like to thank Taiyo Nippon Sanso Corp. for sample preparations.
1. S. Chen, et al., AIP adv. 2, 022149 (2012).
2. S. Chen, et al., J. Appl. Phys. 112, 053513 (2012).
3. S. Chen, et al., Jpn. J. Appl. Phys. 51, 111002 (2012).
4. J. Ladroue, et al., J. Vac. Sci. Technol. A 28, 5 (2010).