Etching characteristics of high-k dielectric HfO2 thin films in inductively coupled fluorocarbon plasmas

Inductively coupled fluorocarbon (CF[4]∕Ar and C[4]F[8]∕Ar) plasmas were used to etchHfO[2], which is a promising high-dielectric-constant material for the gate of complementary metal-oxide-semiconductor devices. The etch rates of HfO[2] in CF[4]∕Ar plasmas exceeded those in C[4]F[8]∕Ar plasmas. The tendency for etch rates to become higher in fluorine-rich (high F∕CF∕C ratio) conditions indicates that HfO[2] can be chemically etched by fluorine-containing species. In C[4]F[8]∕Ar plasmas with a high Ar dilution ratio, the etch rate of HfO[2] increased with increasing bias power. The etch rate of Si, however, decreasd with bias power, suggesting that the deposition of carbon-containing species increased with increasing the power and inhibited the etching of Si. The HfO[2]∕Si selectivity monotonically increased with increasing power, then became more than 5 at the highest tested bias power. The carbon-containing species to inhibit etching of Si play an important role in enhancing the HfO[2]∕Si selectivity in C[4]F[8]∕Ar plasmas

Characterization of porosity and dielectric constant of fluorocarbon porous films synthesized by using plasma-enhanced chemical vapor deposition and solvent process

Fluorocarbon films obtained in plasma-enhanced chemical vapor deposition with a C[4]F[8] compound were composed of a carbon cross-linked network and unlinked species encapsulated in the network [J. Appl. Phys. 89, 893 (2001)]. The unlinked species were effectively removed from the films. Then, the network probably containing the pore of the species was extracted on wafers when the films were dipped into tetrahydrofran (THF) solvent. The fact implied that fluorocarbon porous films with a low-dielectric constant might be formed by using dry and wet processes. In the present study, x-ray analyses showed that the THF-treated films actually became porous in the dipping process. The dielectric constant of the THF-treated films was consistently low (<1.9) and reduced by 10% from that of as-deposited films. The fluorocarbon network as a porous medium may be applied to interlayer dielectrics for ultralarge-scale integrated circuits

Characterization of inductively-coupled RF plasma sources with multiple low-inductance antenna units

We have developed a cylindrical RF plasma source by the inductive coupling of multiple low-inductance antenna (LIA) units and analyzed the plasma density profile of this source using fluid simulation. Experiments using four LIA units showed a stable source operation even at 2000 W RF power, attaining plasma densities as high as 1011 – 1012 cm3 in an argon pressure range of 0.67 –2.6 Pa. The amplitude of antenna RF voltage was measured to be less than 600 V, which is considerably smaller than those obtained using conventional ICP antennas. The radial distribution of plasma density sustained using four LIA units showed excellent agreement with profiles numerically predicted using a fluid-simulation code

Generation of uniform plasmas by crossed internal oscillating current sheets: Key concepts and experimental verification

The results of comprehensive experimental studies of the operation, stability, and plasma parameters of the low-frequency (0.46 MHz) inductively coupled plasmas sustained by the internal oscillating rf current are reported. The rf plasma is generated by using a custom-designed configuration of the internal rf coil that comprises two perpendicular sets of eight currents in each direction. Various diagnostic tools, such as magnetic probes, optical emission spectroscopy, and an rf-compensated Langmuir probe were used to investigate the electromagnetic, optical, and global properties of the argon plasma in wide ranges of the applied rf power and gas feedstock pressure. It is found that the uniformity of the electromagnetic field inside the plasma reactor is improved as compared to the conventional sources of inductively coupled plasmas with the external flat coil configuration. A reasonable agreement between the experimental data and computed electromagnetic field topography inside the chamber is reported. The Langmuir probe measurements reveal that the spatial profiles of the electron density, the effective electron temperature, plasma potential, and electron energy distribution/probability functions feature a high degree of the radial and axial uniformity and a weak azimuthal dependence, which is consistent with the earlier theoretical predictions. As the input rf power increases, the azimuthal dependence of the global plasma parameters vanishes. The obtained results demonstrate that by introducing the internal oscillated rf currents one can noticeably improve the uniformity of electromagnetic field topography, rf power deposition, and the plasma density in the reactor