Speaker
Description
Silicon carbide (SiC) crystal, which has good mechanical and electric properties, is a promising materials. Owing to its ultrahigh-hardness and chemical stability, it is difficult to fabricate structures in micro-nano meter scale by means of conventional fabrication processes. Ion beam technology, which has been successfully applied in industrial fields such as semiconductor devices, is a promising candidate to solve the problem. In previous experiments, a swelling structure, which is fabricated by means of ion-beam induced expansion effect, has been observed for SiC crystal [1, 2]. The object of the present study is to show the feasibility of ion-beam induced swelling effect as a fabrication method for SiC crystal. Based on the experimental results, a fabrication of multi-step structure on SiC crystal has been demonstrated.
Ar-beam, which was prepared by ECR ion source (10 GHz - NANOGAN), was irradiated on 6H-SiC crystal and a swelling height was measured with a profilometer as a function of the fluence. The swelling height has shown clear relation with irradiation parameters, a fluence and energy of Ar beam. The swelling height has increased with the fluence and reached its saturation value at the fluence of $5\times10^{15}$ ions/cm$^{2}$. By using Ar$^{7+}$ beam with 700 keV, the maximum height of 100 nm was obtained. Based on those results, two-step irradiation of Ar beam on 6H-SiC was performed. Irradiation parameters and areas of two independent irradiations were different for each other. Two-step structure has been successfully fabricated by the two-step irradiation. In order to confirm the possibility of the swelling structure as mechanical devices, irradiation-induced modification of mechanical properties of SiC crystal was evaluated by means of nano-indentation method. No serious deteriorations have been observed under the present irradiation conditions.
References
[1] Y. Katoh, H. Kishimoto, A. Kohyama, Materials Transactions (2002) 42:612-616.
[2] M. Ishimaru, I.T. Bae, A. Hirata, Y. Hirotsu, Phys. Rev. B (2005) 72:024116.
