| Dual-frequency capacitively coupled plasma (DF-CCP) source is becoming a new type plasma source in recent years. The plasma is drived by the higher frequency (HF) and the lower frequency (LF) power supply, so the separate control of plasma density and ion energy can be realized in a DF-CCP. The higher etching rate and uniformity can be obtained. DF-CCP can produce uniform plasma in large area. The device operates easily, has a simple structure and lower cost, thus it meets the requirements of the semiconductor industrial production. This plasma source has been widely used, is gradually replacing other less efficient plasma source in dielectric etching. In practice, its uniformity, frequency decoupling and the ion energy distribution for etching are modulated by various discharge parameters. The limitation of DF-CCP has been made, therefore, it is necessary to do an in-depth investigation.It is difficult to do the direct experimental measurement in DF-CCP because of the strong harmonic interference. Specifically, the problem of experimental diagnosis is how to achieve original diagnosis and can not disturb the plasma discharge, obtain the plasma density, electron temperature, electron energy distribution function and ion energy distribution and other valuable data. For this purpose, a newly developed complete floating double probe diagnostic system is used to measure the space plasma density and electron temperature. The coupling effect of dual frequency sources at different discharge parameters is researched. Finally, we research the Ar/O2 mixed gas discharge through the quadrupole mass spectrometry system. The ion energy distribution and average energy are obtained under different discharge conditions. The first three chapters are the introduction, experimental diagnostic methods and experimental setup description. The last three chapters are the main findings. Chapter 4 is the investigation of the spatial uniformity of dual-frequency capacitively coupled plasma, and some of the experimental results are compared with two-dimensional fluid simulation results. Chapter 5 is the investigation of coupling effect in the dual frequency sources, In Chapter 6, we investigate the ion energy distribution and average energy of the Ar/O2 mixed gas discharge.In the first chapter of the introduction, we introduce the low temperature plasma application in microelectronics industry, analyze and compare several common plasma sources, describe the DF-CCP source in detail, review the theoretical and experimental research progess in detail, point out the problems in investigation. Finally, we introduce the investigation contents and arrangement in this thesis. In Chapter 2, we introduce the principle of the common experimental diagnostic methods in detail, including the single probe and double probe method, mass spectrometry, optical emission spectrometry (OES) and absorption spectrometry (AS). Chapter 3 describes our experimental setup, including the DF-CCP discharge device, the newly developed complete floating double probe diagnostic system and quadrupole mass spectrometry diagnostic system.In Chapter 4, the plasma density and electron temperature of the radial and axial distributions at different discharge parameters are investigated using the newly developed complete floating double probe diagnostic system. The results show that pressure, low-frequency power and electrode spacing can influence the radial uniformity obviously, high-frequency power has little effect. If select the appropriate discharge parameters, we can get a good radial uniformity. Electron temperature and plasma density generally have the opposite trend. The axial distribution from the drive electrode to ground electrode displays that the plasma density shows from symmetric to asymmetric parabolic distribution when pressure increases, the maximum biases to the drived electrode. As the pressure increases, ionization source tends to the drived electrode gradually and asymmetric discharge electrodes cause sheath thickness near the electrode becoming asymmetry, resulting in asymmetric axial distribution of plasma density. Increasing high-frequency power can improve the axial plasma density, and low frequency power increase can cause the axial plasma density decreases. Electron temperature has less affected in the axial position, changes smoothly. Two-dimensional fluid simulation is done to this plasma discharge. The results show that experiment and fluid simulation results are consistent.In Chapter 5, we investigate the coupling effect of dual frequency sources using the newly developed complete floating double probe diagnostic system. We analyze the mechanism of the coupling effect by measuring the plasma density and electron temperature in the center of the discharge space. The electrode spacing, pressure and high and low frequency combination have contribution to the coupling effect. The results show that, high and low frequency sources have a strong coupling effect; it is difficult to achieve complete decoupling. Increase the low frequency power, when high frequency power is lower, the plasma diacharge is similar to single-frequency discharge, plasma density will gradually increase; as high frequency power become higher, sheath expansion, the main plasma region decreases, plasma density gradually reduces, but the electron temperature gradually increases. In the small space discharge, the plasma density decreases with the low-frequency power increases. When electrode spacing is large, low-frequency power increase, the secondary electron emission plays an important role, which leads to plasma density increase. When pressure is lower, the plasma density changes little with the low-frequency power increase, it is easier to achieve decoupling, as pressure is high, electron impact becomes intense, ohmic heating efficiency increases, the plasma density also increases, but decreases with increasing pressure under the same high-frequency power. When high and low frequency combination is large, plasma density has a little change, it is easier to achieve decoupling.In Chapter 6, the ion energy distribution and average energy of Ar/O2 mixed gas discharge are investigated using quadrupole mass spectrometer. The diagnostics is in situ because ions enter the mass spectrometer hole directly through the sheath under the low electrode. The low-frequency power, pressure, low-frequency frequency and oxygen content can influence Ar+ and O2+ ions. The results show that when low-frequency power increases, potential increases in the sheath, the ions obtain higher energy through the sheath, the energy of Ar+ and O2+ ions increases, high energy peak moves to high energy area, the energy width increases. More energy of Ar+ ions is lost because of resonant charge exchange reaction, the average energy of Ar+ ions is lower than O2+ ions in different low-frequency power. When pressure rises, collisions of Ar+ ions are more in the process of crossing the sheath, the bimodal structure becomes vaguely, and disappears gradually, but low energy ions are more and more. The influence of pressure to O2+ ions is not obvious because of the smaller ion collision cross section. When low-frequency frequency increases, the ion energy changes from middle-frequency to high-frequency mechanism, the energy width of Ar+ and O2+ ions decrease, bimodal structure becomes vaguely. The oxygen content increases, ionization rate increases, high energy peaks of Ar+ and O2+ ions move to high energy area, the maximum energy value gradually shifts to high energy area. The average energy of Ar+ ions is lower than the O2+ ions under the same condition.
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