Quantitative Analysis on the Growth of Negative Ions in Pulse-Modulated SiH₄ Plasmas

Abstract

The evolutions of chemical species (SiH4, SiH x , SiH x +, and polymerized negative ions) in the pulse-modulated SiH4 plasmas during the plasma-on and -off times were analyzed by solving the model equations of chemical species. During the plasma-on time, the SiH x concentration increases with time, mainly by the generation reaction from SiH4, but during the plasma-off time, it decreases because of the reaction with H2. During the plasma-on time, the concentrations of negative ions increase with time by the polymerization reactions of negative ions, and those become almost zero in the sheath regions because of the electrostatic repulsion. During the plasma-off time, the concentrations of negative ions decrease with time by the neutralization reactions with positive ions, and some negative ions can diffuse toward the sheath regions because there is no electric field inside the reactor. Our theoretical analysis shows quantitatively that the pulse-modulation plasma technique can be an efficient method to reduce the polymerized negative ion clusters, which are not good precursors for a high-quality thin film and which can also be the sources of particle contamination.

Plasma Polymerization of Maleic Anhydride: Just What Are the Right Deposition Conditions?

“…Recent developments in mass-spectral sampling technique have brought forward new evidence on the role of negative ions and cluster formation in pulsed plasma polymerisation systems22, 35, 36. These investigations have clearly shown the presence of cluster ions ranging up to multiple monomer mass units generated by ion-neutral chemistry in gas phase predominantly occurring in the plasma off-period 35, 36. In light of these reports, we extended the study to explore the effects of varying the OFF-time in an attempt to explore the optimal t on / t off ratios to maximise the functional group retention for maleic anhydride plasma polymers.…”

Prediction of TiO<SUB>2</SUB> Thin Film Growth on the Glass Beads in a Rotating Plasma Chemical Vapor Deposition Reactor

“…[10][11][12] Low-temperature plasmas are generated by an inductively coupled rf plasma process with a spiral-shape electrode installed around the reactor. The plasma reactor rotates with a rotation speed, R , to deposit uniformly the precursors of TiO 2 thin films onto the surface of glass beads.…”

“…with aluminum oxide film to increase the chemical stability of the SiC particles. Kim et al [10][11][12] proposed a rotating cylindrical PCVD reactor for uniform particle coating with amorphous Si (a-Si) and suggested that the rotating PCVD reactor could be used to provide thin films on the particles with higher quality of a-Si, as compared with other particle-coating processes.…”

Hard coatings on polycarbonate plate by sol–gel reactions of melamine derivative, poly(vinyl alcohol), and silicates

“…Therefore, it is difficult to make a large size product material. In addition, special techniques are needed to manage the reactants in the sol-gel process [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”