Study of the Impact of H+ Mobile Ions on RF Performances of PECVD TEOS Silicon Dioxide Deposited at Low Temperature

In this paper, we study the impact of H+ mobile ions on Radio Frequency (RF) performances of silicon dioxide deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) at low temperature (200°C), using a tetraethylorthosilicate (TEOS) - oxygen mixture as gas precursor. The presence of H+ ions within the dielectric is related to the low temperature deposition of the dielectric combined with exposition to moisture; the phenomenon is proven with Fourier Transform Infrared Spectroscopy (FTIR) and electrical methods as Transient Voltage Sweep (TVS) and C-V (capacitance-voltage) experiments on MOS (Metal Oxide Semiconductor) capacitors. A CoPlanar Waveguide (CPW) structure is employed to evaluate the RF behavior of the dielectric. It will be shown that the variation of CPW characteristics such as line loss (α) and characteristic impedance (Zc) is due to the interaction between the H+ ions and the substrate.