Growth and sacrificial oxidation of transition metal nanolayers

In vacuo growth studies of Ru thin films on Si, SiN, and SiO2 by high-sensitivity low energy ion scattering

“…2 Due to its low resistivity and low solubility with Cu, 3 Ru has been used as a Cu diffusion barrier and/or Cu seed layer in integrated circuits with copper interconnect technology. 4 Other applications for Ru thin films are as bottom electrode in capacitors based on high-K materials, 5 or as capping layer for optics designed for extreme ultraviolet lithography (EUVL) 6,7,8,9 due to its low sensitivity for oxidation. 10 In the last three applications, diffusion (either copper or oxygen) towards deeper layers is one of the main threats for their performance.…”

Growth and thermal oxidation of Ru and ZrO2 thin films as oxidation protective layers

“…1,2 Due to its low resistivity and low solubility with Cu, 3 it has also been used as Cu diffusion barrier and/or Cu seed layer in integrated circuits with copper interconnect technology. 4 Other applications for Ru are as bottom electrode in capacitors based on high dielectric materials, 5,6 or as capping layer for optics designed for extreme ultraviolet lithography (EUVL) 7,8,9,10 , due to its low-oxidation properties. …”

“…49,50 However, Mo forms a thicker (several nanometers) oxide that continues oxidizing upon air exposure. 8,51 Thus, up to date, multilayer mirrors are normally terminated by Si. 52 Since EUV radiation is highly absorbed by almost all materials, including air, EUV mirrors and the entire EUVL scanners are kept under ultrahigh vacuum (UHV) conditions (e.g., <10…”

“…41,49,128,131 In this line, there are other studies reported that test different protective materials against oxidation on a multilayer (or a single Mo or Si layer, mimicking the last layer of the multilayer), not only by EUV (or e-beam) exposure in presence of water, 132 but also by atomic oxygen, 133 by oxygen plasma, 134 or by ambient air. 8 In addition, several of these studies give some insights on the effect of the growth (thickness, 132 conditions 8 ) on the oxidation resistance of the deposited protective layers.…”

“…As stated in the previous section (Sec. 1.4.3.1), oxidation of polycrystalline Ru is relevant for microelectronic (DRAM, CMOS) devices and EUVL optics, since Ru is used as Cu diffusion barrier and/or Cu seed layer in integrated circuits with copper interconnect technology, 4 as bottom electrode in capacitors based on high dielectric materials, 5,6 or as capping layer for EUVL optics, 7,8,9,10 with a similar polycrystalline (or amorphous) structure far from monocrystalline. …”