Mechanism of Hydrogenated Microcrystalline Si Film Deposition by Magnetron Sputtering Employing a Si Target and H₂/Ar Gas Mixture

Abstract

The mechanism of hydrogenated microcrystalline silicon (µc-Si:H) film deposition by magnetron sputtering employing a Si target and H2/Ar gas mixture has been investigated by measuring Si and H atom densities in the gas phase by laser-induced fluorescence spectroscopy. The crystalline volume fraction of the film correlated positively with H atom density. The variation in Si atom density indicated the increase in sputtering yield from the Si target in the H2/Ar discharge. The surface of the Si target immersed in the H2/Ar discharge was hydrogenated. Therefore, it is reasonable to expect the production of SiHx molecules (typically SiH4) from the hydrogenated Si target via reactive ion etching. Since SiHx molecules produced from the target may function as a deposition precursor, the mechanism of µc-Si:H film deposition is considered to be similar to that of plasma-enhanced chemical vapor deposition (PECVD) employing a SiH4/H2 gas mixture. The advantage of magnetron sputtering deposition over PECVD is the production of SiHx molecules without using toxic, explosive SiH4.

Growth and properties of hydrogenated microcrystalline silicon thin films prepared by magnetron sputtering with different substrate temperatures

“…Figure 3a shows the Raman spectra of lc-Si:H thin films deposited at different substrate temperatures. The Raman spectra of all lc-Si:H thin films have a narrow and predominant peak located at *518 cm -1 , indicating that the thin films contain a crystalline Si structure [11,16]. The peak width becomes narrower as substrate temperature increases, implying that the crystallinity of thin films increases as substrate temperature increases [11,16].…”

“…where I 480 , I 505 and I 520 are the integrated intensities of scattering peaks at *480 cm -1 (amorphous phase), *505 cm -1 (defective part of the crystalline phase) and *520 cm -1 (crystalline phase), respectively [11,16]. The hydrogen bonding configuration and total bonded hydrogen content (c H ) of thin films were determined by FT-IR (Thermo Nicolet 6700) in the wave number range of 4000-400 cm -1 .…”

“…The magnetron sputtering process is a good alternative because it has a capability for large area deposition and process controllability, and, especially, it is a safe process not using toxic and explosive gases [9,10]. Previous studies showed that lc-Si:H thin films can be obtained by frequency (RF) magnetron sputtering with a silicon target when the sputtering discharge is operated with the H 2 /Ar gas mixture [7][8][9]11]. And it was found that the growth and properties of lc-Si:H thin films would be influenced by deposition conditions such as substrate temperature, RF power, total pressure and partial hydrogen and argon dilution [7][8][9][11][12][13][14].…”

“…Previous studies showed that lc-Si:H thin films can be obtained by frequency (RF) magnetron sputtering with a silicon target when the sputtering discharge is operated with the H 2 /Ar gas mixture [7][8][9]11]. And it was found that the growth and properties of lc-Si:H thin films would be influenced by deposition conditions such as substrate temperature, RF power, total pressure and partial hydrogen and argon dilution [7][8][9][11][12][13][14]. The substrate temperature is a crucial deposition condition for optimization of growth and properties of lc-Si:H thin films [14,15].…”

Enhancement of Crystal Growth in Si Thin-Film Deposition by H-Radical-Assisted Magnetron Sputtering

“…The configuration of the sputtering chamber was as follows. 7) A conventional magnetron sputtering source with a pair of cylindrical permanent magnets was inserted from the bottom of a cylindrical vacuum chamber, which was evacuated using a turbomolecular pump below a base pressure of 1 Â 10 À6 Torr. An rf power supply at a frequency of 13.56 MHz was connected to a cathode electrode via an automatic matching circuit.…”