Synthesis of SiOF nanoporous ultra low-k thin film
In this work, we have investigated the effect of annealing temperature on physical, chemical and electrical properties of Fluorine (F) incorporated porous SiO2 xerogel low-k films. The SiO2 xerogel thin films were prepared by sol–gel spin-on method using tetraethylorthosilicate as a source of Si. The hydrofluoric acid was used as a catalyst for the incorporation of F ion in the film matrix. The thickness and refractive index (RI) of the films were observed to be decreasing with increase in annealing temperature with minimum value 156 nm and 1.31 respectively for film annealed at 400 °C. Based on measured RI value, the 34 % porosity and 1.53 gm/cm3 density of the film annealed at 400 °C have been determined. The roughness of the films as a function of annealing temperature measured through AFM was found to be increased from 0.9 to 1.95 nm. The Electrical properties such as dielectric constant and leakage current density were evaluated with capacitance–voltage (C–V) and leakage current density–voltage (J–V) measurements of fabricated Al/SiO2 xerogel/P–Si metal–insulator-semiconductor (MIS) structure. Film annealed at 400 °C, was observed to be with the lowest dielectric constant value (k = 2) and with the lowest leakage current (3.4 × 10−8 A/cm2) with high dielectric breakdown.
KeywordsDielectric Constant Leakage Current Density TMOS MTES Porosity Percentage
Authors would like to acknowledge with thanks the financial assistance provided by CSIR, New Delhi to carrry out this work (vide letter No.03(1127)/28/EMR-II). Authors are also grateful to the Center of Excellence in Nanoelectronics (CEN), IITB (under IIT INUP at IITB which have been sponsored by DIT, MCIT, and Government of India) is also being acknowledged for providing the facility of electrical characterization during this work.
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