This study of the effects of fluorine addition to silicon oxycarbide dielectric barrier was prepared by using SiF 4 , 4MS, and CO 2 as precursors, then reacting in the plasma enhanced chemical vapor deposition system. The addition of fluorine into silicon oxycarbide results in a 50% reduction of effective oxide charges compared with the fluorine-free silicon oxycarbide films. It also improves the dielectric constant, leakage current and breakdown voltage of the bulk film.As feature sizes scale down to several tens of nanometers, interconnect schemes are increasingly dominated by copper and low dielectric constant materials to reduce resistance and capacitance. 1 This trend includes the introduction of an etch stop and a dielectric barrier against copper diffusion. 2-5 In 0.13 m processes and beyond, a barrier of nitrogen-containing silicon carbide ͑SiCN, ϳ 5.0͒ has been used to replace the common nitride barrier ͑ ϳ 7.0͒. 6,7 Recently, oxygen-containing SiCO has been a candidate to replace SiCN as the next-generation dielectric barrier because it does not contain nitrogen and has a lower dielectric constant ͑ Ͻ 4.5͒. 8,9 Furthermore, fluorine-doped silicon oxide glass ͑FSG͒ dielectric has demonstrated better electrical properties and breakdown field strength because of its composition and configuration. 10 The presence of fluorine in the oxide decreases the polarization and hydrogen content of the dielectric, thus reducing the dielectric constant and leakage current. Several studies have found that fluorinated amorphous carbon ͑a-C:F͒ formed in the PECVD system has a lower dielectric constant. 11,12 Those studies have focused on how to introduce fluorine to decrease the dielectric constant, but do not mention doping the copper cap layer for leakage current improvement. This study is the first in which the copper cap layer was fluorine doped, after the chemical mechanical polishing ͑CMP͒ process, to create a dielectric barrier.
ExperimentalSiCOF films were deposited on 12-in. p+ Si͑100͒ wafers using a Novellus plasma-enhanced chemical vapor deposition ͑PECVD͒ system with a tetramethylsilane ͑4MS͒, CO 2 , and SiF 4 precursors. After connecting a 13.6 Mhz radio-frequency ͑rf͒ power source to the top of the PECVD system chamber, SiF 4 was reacted with 4MS and CO 2 in the chamber to form the SiCOF films. During the process, the substrate temperature was maintained at 400°C, total process pressure was 2 Torr, and the rf power was fixed at 1500 W.Capacitance-voltage ͑C-V͒ and current-voltage ͑I-V͒ curves were generated by taking measurements on an metal-insulatorsemiconductor ͑MIS͒ structure ͑1 kÅ thick, final Al dot diameter 0.086 ± 0.004 cm. Prior to measurement, the MIS structures were annealed in N 2 for 30 min at 300°C ͑pressure = 10 −5 Torr͒. The C-V curves were measured using an HP4284 LCR meter sweep voltage −20 to 20 V, forward and backward scanning at 1 MHz in 0.5 V/s increments. The I-V curves were generated with a Keithly 2400 Digital SourceMeter ͑sweep voltage 0 to − 150 V in 0.5 V/S increments͒. The therma...
