Chemical Vapor Deposition of Copper for IC Metallization: Precursor Chemistry and Molecular Structure

Abstract

In the microelectronics industry, integrated circuit (IC) device performance is continually increasing while the critical feature sizes are rapidly decreasing. Since this trend is expected to continue for future generations of ICs, areal density constraints often require that circuit designs utilize multilevel structures with vertical interconnects. It was recently demonstrated that the resistivity of the metal interconnects may limit device performance in multilevel thin-film structures. Although Al metallurgy (Al/2 wt.% Cu alloy) is extensively used for IC metallization today, lower resistivity metals, such as gold, copper, and silver may be necessary for designs requiring feature sizes of 0.25 μm or less. Chemical vapor deposition (CVD) is an attractive technique for the conformal filling of submicron vertical interconnects. For CVD to be generally applicable to IC fabrication, volatile precursors with adequate stability must be designed and optimized. Lastly, IC metallization typically requires that both uniformity and conformality be achieved simultaneously in a single process step.

Selective Metallization of Mg/NH3-Treated Teflon by Copper CVD

“…Gravimetry of the sample indicated that the density of the film (in the range 8.5 ± 0.5 g cm ±3 ) was comparable to that of metallic Cu (r = Once the first 0.5 mm copper layer had been deposited by CVD, classical electroless or electrodeposition procedures allowed thicker deposition (50± 100 mm) in a short time (less than 1 h). The resistivity of the copper films that was measured on 0.5 mm thick films was r = 1.9 ± 0.2 mW cm; this value was comparable to what is generally observed with CVD-deposited films (1.8 mW cm), [4,5] and to the bulk Cu value (1.67 mW cm). Figure 4 shows XPS spectra of a Cu sample before ( Fig.…”

“…Film resistivities between 1.8 and 2.5 mW cm, as opposed to 1.67 mW cm for bulk copper, have been reported. [4,5] In this work, two different precursors were used to check if the phenomenon we observed was precursor dependent: (VTMS)Cu(hfac) and (MHY)Cu(hfac) (where VTMS = vinyltrimethylsilane and MHY = 2-methyl-1-hexene-3-yne). The temperature of the source and the reactor sample plate were slightly dependent on the precursor: 45 C (source)/ 210 C (sample plate) for (VTMS)Cu(hfac) and 65 C (source)/240 C (sample plate) for (MHY)Cu(hfac).…”

“…[1] Generally, the ªactivatedº Teflon is metallized by a two-step process: i) deposition of a conductive seed layer [2] or TiN, [3] ii) electroless deposition or electroplating. Although CVD processes [4,5] have become increasingly important for the deposition of thin metal films and for filling of high-aspect ratio vias in ULSI (ultra large scale integration) multi-level interconnect schemes, just a few groups [6±10] have used copper chemical vapor deposition (CVD) on Teflon substrates. The first study [6±9] showed that patterned copper CVD films could be deposited on Teflon in a three-step process including either electron or X-ray irradiation and etching with a solution of sodium naphthalene.…”

Copper metallization for ULSL and beyond

“…The chemistry of these precursors and CVD processes using such precursors has been reviewed recently.72. 73 The Cul+ (I) precursors are generally available in liquid form, making their delivery into the CVD reactor easy. They decompose on heating through a disproportionation reaction, 2L Cu(I)(P -diketonate) (13) + Cu(0) + Cu(II)(P -diketonate), + 2L leading to a neutral copper atom that deposits on the substrate and a Cu (11) metal-organic compound that is pumped out.…”

Me3SiCC–CMeCH2 copper(I) β-diketonates: Synthesis, solid state structure, and low-temperature chemical vapour deposition

“…Other compounds of the same family have demonstrated valuable results [7,24,25]. Within this family of copper(I) CVD precursors, the physical properties can easily be varied by structural modifications, i.e.…”