| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS-MoM |
| Session: | Plasma Etching for Advanced Interconnects |
| Presenter: | K. Takeda, Nagoya University, Japan |
| Authors: | K. Takeda, Nagoya University, Japan S. Takashima, Nagoya University, Japan R. Saito, Nagoya University, Japan S. Uchida, Nagoya University, Japan M. Fukasawa, Sony Corporation, Japan K. Oshima, Sony Corporation, Japan K. Nagahata, Sony Corporation, Japan T. Tatsumi, Sony Corporation, Japan M. Hori, Nagoya University and JST-CREST, Japan |
| Correspondent: | Click to Email |
The low dielectric constant (low-k) films are widely introduced as interlayer dielectrics for ULSIs. An organic low-k film, polyallylene (PAr), is one of prospective candidates for interlayer films with low-k. PAr receives the damages from the plasmas. The plasma damages induce the increase of the dielectric constant of the films. In our previous studies, we have developed the novel technique for evaluating the damages due to radiation, radicals and ions in plasmas separately (Pallet for plasma evaluation : PAPE) and clarified the generation mechanism of porous SiOCH films using the PAPE in plasma etching using H2 and N2 gases.1 In this technique, a vacuum ultraviolet (VUV) window, an ultraviolet (UV) window, a Si plate, or nothing were placed on low-k films and were irradiated by plasmas. Therefore, we can evaluate the influence of individual VUV radiation, UV radiation, radicals, radicals with radiations, and ions on the damage of films. In this study, the damage induced by H2/N2 plasma was investigated to clarify the generation mechanism of surface changes due to VUV radiation, UV radiation, radicals, radicals with radiation, and ions on the organic low-k films. The dual frequency capacitively coupled plasma apparatus for 8 inch wafer processing was used in this study. VHF (60MHz) and bias (2MHz) powers of 500 W were applied to the upper and the bottom electrodes, respectively. The pressure of H2 and N2 mixture gas was 5.3 Pa. The etching time was 20 s. At a gas flow rate ratio of 50 %, the etching depth of the sample irradiated by radiation, radicals, and ions was approximately 80 nm. The other samples on the conditions without ion bombardment were not etched and the refractive index of the sample irradiated by radiation, radicals, and ions increased significantly compared to the other samples, which indicated that the damages caused by ions were greater than those due to VUV, UV radiation, and radicals. On the other hand, in the pure N2 plasma, the thicknesses and refractive indexes of all samples were not changed. From these results, the damage caused by the ion bombardment was suppressed by surface nitriding of organic low-k film due to N2 plasma exposure. On the basis of results, the generation mechanism of damage is presented.
1 S. Uchida, S. Takashima, M. Fukasawa, K. Ohshima, K. Nagahata, T. Tatsumi , and M. Hori, J. Appl. Phys., 103 (2008) 073303.