Jung-Hyung Kim

The deposition of SiOF film with low dielectric constant in a helicon plasma source

SiOF films deposited by a helicon wave plasma chemical vapor deposition method has been characterized using Fourier transform infrared spectroscopy and ellipsometry. High density plasma of ≳1012 cm−3 can be obtained on a substrate at low pressure (<10 mTorr) with rf power ≳400 W with a helicon plasma source. A gas mixture of SiF4, O2, and Ar was used to deposit SiOF films on 5 in. Si(100) wafers not intentionally heated. Optical emission spectroscopy was used to study the relation between the relative densities of the radicals and the deposition mechanism. It was found that the addition of Ar gas to the SiF4/O2 mixture greatly increased the F concentration in the SiOF film. Discharge conditions such as gas composition, sheath potential, and the relative densities of the radicals affect the properties of the film. The dielectric constant of the SiOF film deposited using the helicon plasma source was 3.1, a value lower than that of the oxide film by other methods.

Frequency dependence of helicon wave plasmas near lower hybrid resonance frequency

The frequency dependence of helicon wave plasmas has been studied at 1–25 MHz of rf power, and at magnetic fields of 200–1150 G using various gases. Maxima in the electron density occur for particular frequencies at each magnetic field. These optimum frequencies are propor-tional to magnetic field strength and inversely proportional to the discharge gas mass. The exist-ence of optimum frequencies in each magnetic field and gas mass indicates the possibility of lower hybridresonance heating effect. The experimental optimum frequencies are slightly lower than the theoretical lower hybrid resonance frequencies. The difference between the two frequencies can be explained by the Doppler shift effect.

A study on ion energy distribution functions and plasma potentials in helicon wave plasmas

The characteristics of high‐density helicon wave plasma generated in a quartz tube of 10 cm in diameter have been studied. The optimum conditions for efficiently exciting helicon wave plasma have been investigated. It is also observed that plasma fully ionized by helicon waves has ion pumping effect. Whether the discharge is inductive or capacitive, the plasma potential is important, since it determines the energy of the ion incident on the wall. It is investigated theoretically and experimentally that the fluctuation of the plasma potentials influences the ion energy distribution functions monitored by the retarding field energy analyzer. It is also observed that the plasma potential fluctuates with peak‐to‐peak voltage Vp–p in the low‐density mode. The radio‐frequency modulation to the plasma potential is weaker in the helicon mode than in the low mode.

m=/spl plusmn/1 and m=/spl plusmn/2 mode helicon wave excitation

The characteristics of plasma produced by plane polarized m=/spl plusmn/1 and m=/spl plusmn/2 mode helicon waves were investigated for the first time. Plane polarized m=/spl plusmn/1 and m=/spl plusmn/2 mode helicon waves were mainly excited using a Nagoya type III antenna and a quadrupole antenna, respectively. Two-dimensional cross-field measurements of ArII optical emission induced by hot electrons were made to investigate the RF power deposition. The components of the wave magnetic field measured with a magnetic probe were compared with the field profiles computed for the m=/spl plusmn/1 and m=/spl plusmn/2 modes. Two and four high intensity plasma columns were observed for the m=/spl plusmn/1 and m=/spl plusmn/2modes, respectively. These columns were located at the regions between the antenna legs. The radial profiles of the wave magnetic field were in good agreement with computations.

A Study on Low Dielectric Material Deposition Using a Helicon Plasma Source

Characteristics of SiOF films deposited by a helicon plasma source have been investigated using Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and ellipsometry. High density Ar plasma of >10 12 cm -3 was obtained on a substrate at low pressure ( 400 W using a helicon plasma source. The effect of the RF power, the magnetic field strength, and the pressure on the helicon wave for high density plasma has been studied. A gas mixture of SiF 4 , O 2 , and Ar was used to deposit SiOF film on 5 in. (100) Si wafers not intentionally heated. Optical emission spectroscopy was used to study the relation between the relative densities of the radicals and the deposition mechanism. The effects of the RF power, the gas composition, and the Ar addition to the SiF 4 /O 2 mixture on the plasma-phase composition and on the properties of the film, have been studied. Discharge conditions such as gas composition, sheath potential, and relative densities of the radicals affect the properties of the film. The dielectric constant of the SiOF film deposited using the helicon plasma source was 3.1, a value lower than that of the oxide films obtained using other methods.

Electrical characteristics of helicon wave plasmas

The external electrical characteristics of helicon wave plasmas have been studied over a wide range of magnetic fields, radio frequency (RF) power, frequencies, and Ar gas pressures. External parameters, such as antenna voltage, current, and phase shifts, and internal parameters, such as electron density, are measured. The equivalent discharge resistance, reactance, and power transfer efficiency are calculated through these measurements. The characteristics of helicon mode is compared with inductively coupled plasma (ICP) and low mode. The power efficiency of the helicon mode is better than that of other modes. Consequently, electron density of helicon mode is much higher than that of other modes. This means the existence of a mechanism where electrons are very efficiently accelerated by the electric field of the antenna in the helicon mode. The power efficiency of helicon mode is higher at lower RF frequency and at optimum gas pressure than that of other modes.

Computational characterization of cutoff probe system for the measurement of electron density

The wave cutoff probe, a precise measurement method for measuring the electron density, was recently proposed. To characterize the cutoff probe system, in this paper, the microwave simulations of a cutoff probe system were performed at various configurations of the cutoff probe system. The influence of the cutoff probe spectrum stemming from numerous parametric elements such as the probe tip length, probe tip distance, probe tip plane orientation, chamber volume/geometry, and coaxial cable length is presented and discussed. This article is expected to provide qualitative and quantitative insight into cutoff probe systems and its optimization process.

M = + 1 MODE HELICON WAVE EXCITATION USING SOLENOID ANTENNA

Abstract In most helicon wave experiments, there has been a poor agreement between the theoretical wave power deposition and the plasma density radial profiles. The characteristics of the solenoid antenna employed for the excitation of m = 1 mode helicon waves are investigated. A cylindrical high density plasma column with high intensity ArII emission is observed to be of a cylindrical shell shape. In cross section, the location of the high intensity column nearly coincides with the maximum point of wave power deposition. The wave magnetic field radial profiles agree well with computations. These results show an excellent agreement between the theory and density profile produced by the m = 1 helicon wave.

The plasma characteristics and film formation generated by the electron cyclotron resonance mechanism

Silicon nitride thin film (SiN/sub x/) is deposited onto the 3 inch silicon wafer using an electron cyclotron resonance (ECR) plasma apparatus. The plasma parameters from N/sub 2/-SiH/sub 4/ electron cyclotron resonance plasma are obtained. Radial distribution of radical atom density is determined by optical emission spectroscopy. From the comparison of the uniformities of deposited film thickness, electron density and radical atom density, it was concluded that the uniformity of film thickness is related to that of radical density rather than plasma density. The dependence of the uniformity film thickness on the waveguide mode was also examined. >

Cutoff probe using Fourier analysis for electron density measurement

This paper proposes a new method for cutoff probe using a nanosecond impulse generator and an oscilloscope, instead of a network analyzer. The nanosecond impulse generator supplies a radiating signal of broadband frequency spectrum simultaneously without frequency sweeping, while frequency sweeping method is used by a network analyzer in a previous method. The transmission spectrum (S21) was obtained through a Fourier analysis of the transmitted impulse signal detected by the oscilloscope and was used to measure the electron density. The results showed that the transmission frequency spectrum and the electron density obtained with a new method are very close to those obtained with a previous method using a network analyzer. And also, only 15 ns long signal was necessary for spectrum reconstruction. These results were also compared to the Langmuir probes measurements with satisfactory results. This method is expected to provide not only fast measurement of absolute electron density, but also function in other diagnostic situations where a network analyzer would be used (a hairpin probe and an impedance probe) by replacing the network analyzer with a nanosecond impulse generator and an oscilloscope.