CVD and ALD Co(W) Films Using Amidinato Precursors as a Single-Layered Barrier/Liner for Next-Generation Cu-Interconnects

Abstract

Cobalt film with tungsten addition [Co(W)] has the potential to be an effective single-layered barrier/liner in Cu-interconnects owing to its good adhesion with Cu, a lower resistivity than TaN, and an improved barrier property with respect to cobalt films. Our previous study on chemical-vapor-deposited (CVD) Co(W) using carbonyl precursors clarified, however, that WO3 included in the films increased the resistivity. In this current study, to reduce the resistivity of Co(W), oxygen-free process for Co(W) films were designed using two oxygen-free amidinato precursors, bis(N-tert-butyl-N′-ethylpropionamidinato) cobalt and bis(tert-butylimino)bis(dimethylamino)tungsten, by chemical vapor deposition (CVD) and atomic layer deposition (ALD) at 350–400°C. Deposition process were designed by employing quantum chemical calculation, in which NH3 were chosen as a reducing reagent for the sake of the low activation energy of deposition. NH3 actually acted effective reducing reagent for Co or Co(W) deposition using amidinato precursors in our research. Co(W) films using amidinato precursors and NH3 contained no oxygen and a few amounts of nitrogen. Nitrogen, however, were easily eliminated by annealing at 400°C. Therefore, Co(W) films using amidinato precursors were so high quality to have lower resistivity than Co(W) films using carbonyl precursors or conventional PVD-TaN.

Atomic Layer Deposition of Intermetallic Co3Sn2 and Ni3Sn2 Thin Films

“…Intermetallic phases in Pt–In, Pt–Sn, and Ni–Fe systems have been obtained by the postdeposition reduction of the corresponding ALD oxides. There are also some ALD studies on metal alloys, such as Pt–Ir, Pd–Pt, Ru–Pt, Ru–Co, Co–W, Co–Pt, Ru–Mn, and Cu–Mn, but no reports exist on materials exhibiting a specific intermetallic structure. Co–Sn and Ni–Sn with varying stoichiometry, including the intermetallic Co 3 Sn 2 and Ni 3 Sn 2 phases, have generally been prepared by, for example, ball milling, melting, different solution‐based techniques, solvo‐ and hydrothermal routes, electrodeposition, sputtering, and electron beam evaporation .…”

Precursor-based designs of nano-structures and their processing for Co(W) alloy films as a single layered barrier/liner layer in future Cu-interconnect

“…8 Therefore, other materials that are less negatively inuenced by impurities must be developed for the sidewall. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] Specically, thinner, single-layer barrier/liner lms with low resistivities formed by CVD or ALD are desired for Cu interconnects of 10 nm and below for next-generation ULSI devices. Such single-layer barrier/liner materials that act as both a barrier and liner to reduce the overall thickness of the sidewall can be designed using surface engineering and metallurgical principles.…”

Role of W and Mn for reliable 1X nanometer-node ultra-large-scale integration Cu interconnects proved by atom probe tomography

“…Co(W) can be used to form a combined diffusion barrier and liner, [11][12][13][14] and Co(W) grown by atomic layer deposition (ALD) has been shown to exhibit favorable adhesion strength with Cu compared with Ta, together with a lower resistivity than TaN, and provides comparable diffusion barrier properties to TaN. 11,12,14 These properties have been evaluated numerically in previous studies; the diffusion barrier property has been investigated in Co(W) based on the Cu diffusion coefficient, and the adhesion strength has been investigated by evaluating the wetting angle of Cu grains formed by annealing the Cu film overlying Co(W).…”

“…The W content was optimized based on the results of our previous studies to achieve good adhesion strength with Cu with favorable barrier properties and resistivity. 11,13,14,16 Co[ t Bu-Et-(Et)amd] 2 , bis(tert-butylimido)-bis-(dimethylamino)tungsten(IV) [BTBMW], and NH 3 were used as the Co precursor, W precursor, and reducing agent, respectively, and were selected as a suitable precursor combination to eliminate the incorporation of O impurities into the film. Details of the ALD of Co(W) have been reported previously.…”

“…Details of the ALD of Co(W) have been reported previously. 13 Seed layers formed of Cu or Cu(Mn) [Mn: 7.1 at. %] were deposited using CVD at 200 C with our another homemade shower-head-type warm wall chamber.…”