We have developed a broad-band technique for measuring the relative permittivity of low-thin films using microstrip transmission-line measurements. From measurements of the complex microstrip propagation constant and the characteristic impedance, we determined the relative permittivity of thin films incorporated in microstrip lines. We present measurement results to 40 GHz for both an oxide and a bisbenzocyclobutene lowthin film and show a variability of permittivity of approximately 5% over the entire frequency range.

Three new aspects regarding the analysis of Langmuir probe data are presented. First, we demonstrate that the numerical results of Laframboise for spherical probes can be parametrized easily for arbitrary ratios of the probe radius rp to the Debye length λD. The ion current can be expressed in the form a(−X)b, where a and b are parameters depending on rp/λD, and X is the dimensionless probe voltage. This functional form is the same as the one for cylindrical probes reported previously, but the values of a and b are different. Second, we use numerical simulations to show that unless the plasma potential Vs is known, it is in general difficult to determine accurately the form of the ion current characteristic Ii(Vp), and thus the ion density Ni, from typical probe data. This is because Ii(Vp), Ni, and rp/λD are interdependent. Third, the simulations indicate that the apparent electron energy distribution is very sensitive to the exact form of Ii(Vp) and to the method by which Ii(Vp) is subtracted from the total probe current to obtain the electron current. A linear extrapolation of Ii(Vp) is often adequate for determining the electron temperature, but assuming a constant ion current leads to electron energy distributions that appear to have two components with different electron temperatures. Additional issues discussed include the consequences of a slightly collisional probe sheath and the importance of end-effect corrections with a cylindrical probe.

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In situ steam generated (ISSG) oxides have recently attracted interest for use as gate dielectrics because of their demonstrated reliability improvement over oxides formed by dry oxidation. [G. Minor, G. Xing, H. S. Joo, E. Sanchez, Y. Yokota, C. Chen, D. Lopes, and A. Balakrishna, Electrochem. Soc. Symp. Proc. 99-10, 3 (1999); T. Y. Luo, H. N. Al-Shareef, G. A. Brown, M. Laughery, V. Watt, A. Karamcheti, M. D. Jackson, and H. R. Huff, Proc. SPIE 4181, 220 (2000).] We show in this letter that nitridation of ISSG oxide using a remote plasma decreases the gate leakage current of ISSG oxide by an order of magnitude without significantly degrading transistor performance. In particular, it is shown that the peak normalized transconductance of n-channel devices with an ISSG oxide gate dielectric decreases by only 4% and the normalized drive current by only 3% after remote plasma nitridation (RPN). In addition, it is shown that the reliability of the ISSG oxide exhibits only a small degradation after RPN. These observations suggest that the ISSG/RPN process holds promise for gate dielectric applications.