| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS2-TuM |
| Session: | Advanced FEOL/Gate Etching |
| Presenter: | A. Raley, TEL Technology Center, America, LLC |
| Authors: | A. Raley, TEL Technology Center, America, LLC B. Parkinson, TEL Technology Center, America, LLC A. Ranjan, TEL Technology Center, America, LLC S. Keisuke, TEL Technology Center, America, LLC K. Kumar, TEL Technology Center, America, LLC P. Biolsi, TEL Technology Center, America, LLC |
| Correspondent: | Click to Email |
Spacer design and materials for planar and FINFET transistors has becomes increasingly critical as gate length is shrinking. For technology node of 22nm and beyond, fringe capacitance between gate and contact/epi-facet are becoming significant component of device degradation.1 Spacer films with low dielectric constant (Low-k spacer) minimize parasitic capacitances because low permittivity can reduce gate-fringing field effects. Several materials and methods for low-k spacers have been reported showing improved device performance2,3. Incorporation of oxygen, boron, and carbon into SiN spacer film to form SiOCN or SiBCN low-k films with oxygen, boron and carbon contents tuned to minimize k value and provide good leakage performance are two of the low-k avenues being explored. Etching of these materials versus conventional SiN spacer has been characterized in simulated wafer product environment and demonstrated on FINFET structure using RLSA™ microwave plasma reactor with radial line slot antenna. RLSA™ microwave plasma source yields high ion flux with tunable ion energies to control polymer passivation. This is key to achieve the high SiN/Si and SiN/SiO2 selectivities mandated by long over etch requirement in the FINFET spacer scheme. The etching mechanisms of low-k films have been compared to that of SiN and SiO2 and it has been shown to strongly depend on the oxygen content of the film. A systematic study on process parameters impact on low-k film etching rate versus SiN and SiO2 will be presented. Optical emission spectra analysis of relative intensities of the following species F, B, H, CF2, and O will be analyzed. Impact of electron energy distribution (tuned by source power and pressure) and ion angular energy distribution (tuned by bias power and pressure) on the species considered will be shown to explain selectivity mechanisms and etch rate trends.
1. Kuhn, K, “22 nm Device Architecture and Performance Elements”, IEDM, 2008
2. Ko, C.H, “A novel CVD-SiBCN Low-k spacer technology for high-speed applications”, VLSI Technology Symposium, 2008, p108-109
3. Huang, E., “Low-k spacers for advanced low power CMOS devices with reduced parasitic capacitances”, SOI Conference, 2008. SOI. IEEE International, p10-20