Study Of ICP Enhanced CCP Discharge By Optical Emission Spectrum Diagnosis

With the rapid development of microelectronics industry, the feature size of integrated circuits(ICs) is getting smaller and smaller. This has put forward the demand for new plasma sources with higher plasma density and better uniformity. People have paid more attention to the research and diagnosis of new plasma sources.Now dual-frequency capacitively coupled plasma(DF-CCP) is widely used in microelectronics industry for its independent control of the ions’ flux and energy. For getting higher plasma density and better uniformity, we have combined inductively coupled plasma(ICP) and CCP and realized ICP enhanced CCP discharge. This paper studied H2+Ar and N2 discharge by optical emission spectrum(OES) diagnosis. This paper also studied the effect of H2+Ar plasma treatment on the optical, electrical, and structural properties of Al-doped zinc oxide(AZO) thin films prepared by radio frequency magnetron sputtering. The following results were obtained:The effect of power on the properties of H2+Ar plasma was studied by OES. The intensity of Ar line at 750.4 nm increased obviously with the increase the ICP(13.56 MHz) power while the higher frequency(60 MHz) and lower frequency(2 MHz) had much less effect on the line intensity. All of these indicated that the addition of ICP discharge could effectively increase the electron density. The electron density was calculated by an OES method which was called Boltzmann plot method, and the electron density increased evidently with the increase of lower frequency power. This study also found that lower frequency power had the greatest influence on H atoms density and the increase of higher frequency power even made the density reduced.As we known, gas temperature is a very important parameter of plasma for thin film deposition and etching. The rotational temperature and vibrational temperature of N2 molecule were got by fitting the measured and calculated spectrum of transition. The vibrational temperature was found much higher that the rotational temperature because the de-excitation rate of rotational and vibrational energy levels of the N2 were much faster than the energy exchange. The vibrational temperature increased first and then increased slowly with the increase of lower frequency power due to the effect of electron density and electron temperature. 3 3u gC ? ?B ?AZO films prepared by magnetron sputtering were treated by H2+Ar plasma. The structural, electrical, and optical properties of the films were studied as a function of lower frequency power. All films exhibited strong(002) diffraction peaks of hexagonal wurtzite structure. The surface roughness increases with the increase of LF power due to the etching effect of hydrogen. H2+Ar plasma can significantly decrease the resistivity of AZO films due to the desorption of negatively charged oxygen species, formation of shallow donors generated by incorporated hydrogen, and passivation of surface and defects at grain boundaries. The resistivity of as deposited films is 1.13×10-2 Ωcm, and then decreases to 4.81×10-3Ωcm with LF power of 60 W. The transmittance of the films with plasma treatment is improved, and the absorption edge shifts to the short wavelength region due to Burstein-Moss effect.