Effect of electron energy probability function on plasma CVD/modification in a 13.56 MHz hollow cathode discharge

Abstract

Langmuir probe diagnostics is done on a RF hollow cathode discharge system (13.56 MHz, 200 W) by inserting a single cylindrical probe in the remote region (50 mm away from the primary argon plasma) and at a distance of 10 mm above the substrate holder. The effects of argon gas pressure, the injection of helium in the remote zone and the substrate bias on the measurements of the electron energy probability function (EEPF) and on the plasma parameters (electron density (ne), effective electron temperature (Teff), plasma potential (Vp) and floating potential (Vf)) have been investigated. The EEPFs and plasma parameters obtained have been used to control two remote plasma processes. The first is the remote plasma enhanced chemical vapour deposition (PE-CVD) of thin films, on silicon wafers, from a hexamethyldisiloxane precursor diluted in the remote Ar–He plasma, where the relative thicknesses of the deposited films were investigated by the ex situ Rutherford back-scattering (RBS) technique. The second is the pure argon remote plasma treatment of a polymethylmethacrylate polymer surface, where the reflectance of the modified surface was measured and compared with the untreated one. It is revealed that by varying the gas mixture/pressure and substrate bias, one can engineer the EEPFs to enhance the desired plasma chemical gas phase reactions thus controlling the plasma CVD and plasma surface modification processes. Auxiliary optical emission spectroscopy diagnostics are discussed as well.

Growth Rate and Sensing Properties οf Plasma Deposited Silicon Organic Thin Films from Hexamethyldisilazane Compound

“…The experimental setup of the plasma device, OES system, single Langmuir probe and the deposition system from liquid precursors such as HMDSN are described in detail in our previous works [11][12][13][14]. Briefly, the plasma source is a hollow cathode discharge (HCD) configuration, which consists of two coaxial tubes of 300 mm length.…”

“…Therefore, the plasma phase, prior to the injection of HMDSN vapor precursor has been characterized. Because of the dominant role of electrons in the plasma phase reactions, it is important to measure both the electron density (n e ) and the electron temperature (T e ), where they were measured at the position of the QCM head using cylindrical single Langmuir probe as described in detail in a previous work [13]. The ion flux rate (ion bombardment of the surface) is also an important parameter in plasma processing, therefore it has been measured using a planar probe as described in [14].…”

“…The UV and VUV photons play an important role in plasma CVD process [13]. Therefore the emitted light intensity integrated over the 200-400 nm UV range was measured using photon counting method, where the VUV (below 200 nm) emission was not measured due to the limitation of our OES system in wavelength and in detector spectral response.…”

Polymer surface modification using He/O2 RF remote low‐pressure plasma

“…The experimental setup of the HCD‐L‐300 system and the plasma characterization facilities are described in previous works 11,12 . Briefly, the plasma source is a hollow cathode configuration, which consists of two coaxial tubes of 300‐mm length.…”

“…The electron energy distribution function (EEDF: g e ( ε )) is related to the EEPF as g e ( ε ) = ε 1/2 f e ( ε ). The electron density ( n e ) and the effective electron temperature ( T eff ) were calculated from the integrals of the EEDF as follows 12,18 : where ε max is determined by the dynamic range of the EEDF measurement.…”