| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThP |
| Session: | Plasma Science Poster Session |
| Presenter: | G.S. Upadhyaya, University of Wisconsin-Madison |
| Authors: | G.S. Upadhyaya, University of Wisconsin-Madison J.L. Shohet, University of Wisconsin-Madison |
| Correspondent: | Click to Email |
In this work, the effects of vacuum-ultraviolet (VUV) radiation on plasma-induced charging of patterned-dielectric structures are investigated. Experimental results show that supplemental-VUV radiation exposure of patterned dielectrics is beneficial in minimizing the plasma-induced charge on patterned-dielectric structures. The results of this work indicate that exposure of patterned-dielectric materials to VUV radiation during plasma processing can be useful in reducing or eliminating structural and electrical damage caused to patterned dielectrics by electron shading. Investigation of the effects of VUV radiation on the plasma charging of dielectrics was accomplished by evaluating the response of unpatterned, plasma-charged, oxide-coated samples exposed to monochromatic-synchrotron-VUV radiation at the University of Wisconsin-Synchrotron Radiation Center. VUV exposure of unpatterned SiO2/Si wafers indicated that photon energies less than or equal to 11 eV are beneficial in depleting the plasma-induced charge. The radiation-response experiments were subsequently extended to include patterned-dielectric wafers. Specialized, patterned-test structures with different aspect ratios (depth/width of a pit) were charged in a DC plasma and subsequently exposed to monochromatic-synchrotron-VUV radiation. Surface-potential measurements revealed significant charge depletion for photon energies in the range from 8-11 eV thereby indicating the beneficial effect of VUV radiation during plasma processing of patterned dielectrics. In addition, it was observed that the number of photons required to deplete charge in patterned dielectrics increases with the increasing aspect ratio of the pits in the patterned wafer. The experimental results are explained with equivalent-circuit models which suggest that electron photoinjection from the Si substrate as well as oxide surface conductivity play an important role in depleting the plasma-induced charge on the patterned-dielectric materials. Thus, we conclude that plasma-charging-induced damage in patterned-dielectric materials can be minimized by supplemental VUV exposure of the wafers during plasma processing.
Work supported by NSF under Grant DMR-0306582 and in part by the Semiconductor Research Corporation under Contract 2008-KJ-1781. The UW Synchrotron is a National Facility supported by NSF under Grant DMR-0084402. *G.S. Upadhyaya present address: Lam Research Corp., Fremont CA. .