Tantalum diffusion barrier grown by inorganic plasma-promoted chemical vapor deposition: Performance in copper metallization

Abstract

As-deposited and annealed tantalum films, grown by plasma-promoted chemical vapor deposition (PPCVD) using pentabromotantalum and hydrogen as coreactants, were evaluated as diffusion barriers in copper metallization. Stacks consisting of 500-nm-thick sputtered Cu/55-nm-thick untreated PPCVD Ta/Si were annealed in argon in the range 450 to 650 °C, in 50 °C intervals, along with sputtered Cu/preannealed PPCVD Ta/Si and sputtered Cu/sputtered Ta/Si stacks of identical thickness. Pre- and postannealed stacks were characterized by x-ray photoelectron spectroscopy, Auger electron spectroscopy, Rutherford backscattering spectrometry, hydrogen profiling, x-ray diffraction, atomic force microscopy, sheet resistance measurements, and Secco chemical treatment and etch-pit observation by scanning electron microscopy. The sputtered and preannealed PPCVD Ta films acted as viable diffusion barriers up to 550 °C, while the as-deposited PPCVD Ta films failed above 500 °C. In all cases, breakdown occurred through the migration of Cu into Si, rather than an interfacial reaction between Ta and Si, in agreement with previously reported results for sputtered Ta films. The accelerated barrier failure for as-deposited PPCVD Ta might have been caused by the presence of approximately 20 at.% hydrogen in the as-deposited PPCVD Ta, an observation which was supported by the enhanced performance of the same PPCVD Ta films after annealing-induced hydrogen removal.

Atomic layer deposition of metal and nitride thin films: Current research efforts and applications for semiconductor device processing

“…Thus, halide precursors are the only commercially available metal precursors for Ta CVD currently. While Ta CVD using chloride requires rather high growth temperature, Ta films were deposited at 450 °C using plasma-enhanced CVD with TaBr 5 and hydrogen plasma, (149,150) The only reported Ta ALD was a plasma enhanced process. (27,43) When TaCl 5 was used as metal precursor and atomic hydrogen produced by RF plasma as reducing agent, amorphous Ta thin films have been deposited at temperatures below 250 °C.…”

Competing reactions during metalorganic deposition: Ligand-exchange versus direct reaction with the substrate surface

“…2,7,9,11,[111][112][113][114][115] These volatile and relatively easy to handle precursors have dominated the field of diffusion barrier film deposition for nearly three decades. 114,[117][118][119][120] Hafnium alkylamides (for example, tetrakis-(dimethylamido)-hafnium, Hf[N(CH 3 ) 2 ] 4 ) have a set of remarkable properties as precursors for growth of a variety of Hfcontaining films, 34,115,[121][122][123][124][125][126][127] including hafnium dioxide, a high-k dielectric material with a wide range of current and potential applications. 12,[47][48][49][50]116 Contamination has been reduced with the use of ALD schemes (with water or ammonia as secondary precursors for the respective growth of oxides and nitrides); various post-treatment methods have also led to dramatic improvements of the deposited films.…”

Investigation of Chemically Vapor Deposited Tantalum for Medium Caliber Gun Barrel Protection

“…Chemical vapor deposition (CVD) offers promising solutions to the problems associated with IM-CMS coatings. Reported studies have demonstrated the use of CVD in producing Ta coatings from tantalum halide sources [1][2][3][4][5]. High quality CVD Ta coatings were produced with excellent step coverage in sub-micron trench structures with high aspect ratios as shown below in Figure 1…”