Low-Temperature Atomic Layer Deposition of High Purity, Smooth, Low Resistivity Copper Films by Using Amidinate Precursor and Hydrogen Plasma

Abstract

Agglomeration is a critical issue for depositing copper (Cu) thin films, and therefore the deposition should be preferably performed below 100 °C. This work explores an atomic layer deposition (ALD) process for copper thin films deposited at temperature as low as 50 °C. The process employs copper(I)-N,N'-di-iso-propylacetamidinate precursor and H 2 plasma, which are both highly reactive at low temperature. The deposition process below 100 °C follows an ideal self-limiting ALD fashion with a saturated growth rate of 0.071 nm/cycle. Benefited from the low process temperature, the agglomeration of Cu thin films is largely suppressed, and the Cu films deposited at 50 °C are pure, continuous, smooth, and highly conformal, with the resistivity comparable to PVD Cu films. In-situ reaction mechanism studies by using quartz crystal microbalance and optical emission spectroscopy are followed, and the results confirm the high reactivity of the Cu amidinate precursor at low temperature. To the best of our knowledge, this is the first successful implementation of metal amidinate precursors for low-temperature (~50 °C) ALD process. The strategy of using metal amidinate precursors in combination with highly reactive H 2 plasma is believed to be extendable for the depositions of other pure metals at low temperature.

Atomic layer deposition of vanadium oxide thin films from tetrakis(dimethylamino)vanadium precursor

“…Deconvolution of the high-resolution V 2p 3/2 spectrum [ Fig. 3(b)] suggested the presence of both V 41 (516.2 eV) and V 51 (517.6 eV) in the film, 37 but further attempts to quantify the V 41 /V 51 ratio were found to involve too much uncertainty to draw any solid conclusions. 28 All the as-deposited VO x films were amorphous, as there were no peaks in their XRD spectra.…”

“…The m 1 /m 0 ratio can be further used to analyze the surface reaction mechanism. 41 As dimethylamino metal precursors are commonly suggested to follow ligand-exchange mechanisms, [42][43][44] we first assume that this ALD VO x process follows a simple ligand-exchange mechanism, and the associated two half-cycle reactions are rewritten as the following:…”

Fabrication of iron carbide by plasma-enhanced atomic layer deposition

“…The PEALD setup includes a deposition chamber and a lowpressure dielectric barrier discharge (DBD) apparatus. The details of the chamber have been given in our previous publications [34,35,36]. The deposition chamber consists of a 60-cm-long fused silica tube (id 50 mm) and a half-cylinder aluminum rod placed along the axis of the outer tube as the sample holder.…”

Recent progress on non-thermal plasma technology for high barrier layer fabrication

“…Based on these properties, ALD thin films can provide much lower permeability. Moreover, the NTP can be used to assist the ALD technique, which is named PEALD or plasma-assisted ALD (PAALD), for a lower temperature and a faster deposition rate process [79,80]. Mourey et al [81] had used low-reactivity oxidants (CO 2 or N 2 O) in PEALD for Al 2 O 3 and ZnO depositions.…”