Low-temperature plasma-enhanced atomic layer deposition growth of WN_xC_y from a novel precursor for barrier applications in nanoscale devices

Abstract

A low-temperature plasma-enhanced atomic layer deposition (PEALD) process has been developed for the growth of ultrathin WNxCy films, using a halide-free W precursor. A 32-nm-thick PEALD WNxCy film deposited using this process at 250 °C possesses a composition of W72C20N5, resistivity of ∼250 μΩ·cm, a root-mean-square (rms) surface roughness of 0.23 nm, and a thickness conformality of more than 80% on trench structures with a width of 120 nm and an aspect ratio of 11. The WNxCy films exhibited excellent thermal stability, whereby resistivity, thickness, surface roughness, and crystal structure were stable after 30 min anneals in 700 Torr, forming gas ambient at temperatures up to 700 °C. Copper diffusion barrier performance measurements show that a 9 nm thick WNxCy film could prevent copper diffusion after a 30 min anneal at 700 °C, while a 2-nm-thick film could prevent copper diffusion after a 30 min anneal at 500 °C.

Development of plasma-enhanced atomic layer deposition grown Ru–WCN mixed phase films for nanoscale diffusion barrier and copper direct-plate applications

“…4 is a cross-sectional TEM of an 11:1 Ru:W ratio film grown with four alternating growth cycles. 14,26 This agrees with the depth profiles shown in Fig. Instead, the overall film structure appears to be comprised of individual grains within an amorphous matrix.…”

“…7,8 Likewise, while TaN is a reasonably robust barrier, it is not an appropriate surface, electrochemically speaking, for copper plating. 14,15 As features in interconnects shrink in size to align with the requirements of the International Technology Roadmap for Semiconductors ͑ITRS͒, it becomes more difficult to employ traditional liner growth methods, such as sputtering. However, these systems suffer from the same fundamental issue with respect to extendibility and scalability as do more conventional barrier/seed stacks.…”

Synthesis of Doped, Ternary, and Quaternary Materials by Atomic Layer Deposition: A Review

“…In the majority of cases found in Tables –, the supercycle scheme is used to combine two separate binary ALD processes that share one element (e.g., O, N, S) into a single ternary process. Some studies implement deposition with multiconstituent precursors to introduce more than one atom into the film with a single precursor, ,,− ,,,,− and others eschew the supercycle pulsing strategy in other ways ,,,− ,− as discussed in Section ; however, these are far less common among the works shown in the tables. Regarding the use of these alternative approaches, Si-containing compounds are of particular note as SiO 2 itself is often difficult to grow on its own. ,,,,,, A number of studies have successfully deposited Si-containing materials by ALD by using precursor strategies other than supercycles.…”

Highly Conformal Amorphous W–Si–N Thin Films by Plasma-Enhanced Atomic Layer Deposition as a Diffusion Barrier for Cu Metallization

“…19 For the W-based ternary nitride, most studies focused on the ALD growth of W−C−N film. Three different kinds of reaction schemes were reported for preparing ALD W−C−N films, including the sequential supplies of (i) W-containing inorganic precursor, WF 6 , carbon-containing precursor, triethylboron [(CH 3 ) 3 B], and NH 3 as a reactant, 22,23 (ii) W-and C-containing metallorganic precursor, W(N t Bu) 2 ( t Bu 2 pz) 2 ( t Bu 2 pz =3,5-ditert-butylpyrazolato) and NH 3 as a reactant, 24 and (iii) W-, C-, an d N -c o n t a in i n g m et a ll o r g an i c p r ec ur s o r , ( 5ethylcyclopentadienyl)dicarbonylnitrosyltungsten and H 2 plasma as a reactant 25 at temperatures ranging from 250 to 450 °C. The failure temperature of ALD W−C−N diffusion barrier (12 nm), determined by X-ray diffractomerty (XRD) and sheet resistance measurement, was as high as 700 °C for 30 min annealing owing to both high density and noncolumnar grain structure.…”