Effect of Plasma Treatments on the Interface Chemistry and Adhesion Strength Between Cu Metallization and SiCN Etch Stop Layer

Abstract

In this study, the interface chemistry and adhesion strengths between Cu and SiCN etch stop layers have been investigated under different plasma treatments. From the examination of interface microstructures and the analyses of chemical compositions and bonding configurations, an oxide layer was found to exist at the untreated Cu∕SiCN interface. After H2 and NnormalH3 treatments, the amount of oxides was effectively reduced. Some Cu silicides formed during SiCN deposition, and Cu nitrides even formed under NnormalH3 plasma treatment. The adhesion strengths of the Cu∕SiCN interfaces were measured by nanoindentation and nanoscratch tests under which interface delamination occurred around indented regions. The adhesion energy of the untreated Cu∕SiCN interface was obtained as about 4.98 and 0.98J∕normalm2 , respectively, by nanoindentation and nanoscratch tests. After H2 and NnormalH3 plasma treatments, the adhesion energy was effectively improved to 5.90 and 5.99J∕normalm2 by nanoindentation test, and to 1.74 and 2.58J∕normalm2 by nanoscratch test, respectively, because of the removing of oxides and the formation of Cu silicides and nitrides at the Cu∕SiCN interfaces.

Effect of NH[sub 3]/He Plasma Treatment on Electrical Reliability and Early-Stage Electromigration Behavior of Copper Interconnects

“…20 During the subsequent deposition of the SiCN capping layer, a CuSi or even CuSiN interlayer might form due to the reaction of the SiCN precursor to the Cu surface or to the CuN layer, as reported. 20,26,27 The formation of a CuN, CuSi, or CuSiN interlayer would enhance the adhesion of the Cu/SiCN interface, 20 which was believed to reduce the rapid diffusion paths of Cu atoms and therefore to improve the EM resistance of Cu interconnects, 7,19 consistent with the reliability results obtained in the present study. Figure 6 shows the FIB and HRTEM images around the M1 Cu/SiCN interface of the EM-tested Cu interconnect structure without a NH 3 /He plasma treatment as the electrical resistance of the tested structure increased to 1.004R 0 .…”

“…5a͒ and previous XPS analyses. 20 It was then realized that at the very early stage of EM tests, due to the existence of oxide at the Cu/SiCN interface without the plasma treatment as aforementioned, Cu atoms on the wire surface just adjacent to the weak Cu/SiCN interface ͑more exactly the Cu/Cu 2 O interface͒ most probably migrated first along the interface as a rapid diffusion path, and voids consequently nucleated and grew at the interface. In comparison, Fig.…”

“…Therefore, many types of surface cleaning and plasma treatments have been extensively developed to change the interface microstructure ͑to remove oxides and to form a CuSi, CuN, or even CuSiN interlayer͒ and to improve the interface adhesion and the consequent electrical reliability. [17][18][19][20][25][26][27] Nevertheless, most of the previous studies focused on the reliability improvement of interconnects; how the plasma treatments influence the very early-stage EM-induced voiding behavior has not been clarified. Thus, in this study, EM reliability tests of dual-damascene Cu interconnect structures with or without applying a NH 3 /He mixed plasma treatment were performed.…”

A Three-Step Atomic Layer Deposition Process for SiNx Using Si2Cl6, CH3NH2, and N2 Plasma

“…As the dimensions of semiconductor devices continue to shrink past the current 14 nm technology node, the deposition of ultrathin, highly conformal films on high-aspect-ratio nanostructures becomes necessary . Of the many different types of films used in semiconductor manufacturing, the highly conformal growth of silicon nitride (SiN x ) is critical for applications such as sidewall spacers and etch stop layers. , To further improve the versatility of the SiN x films, incorporation of C may be required to tune the dielectric properties for specific applications . Because of the thermal budget limitations, a substrate temperature ≤400 °C is desired for the SiN x growth .…”

Atomic Layer Deposition of SiCxNy Using Si2Cl6 and CH3NH2 Plasma

“…The fabrication of next-generation semiconductor devices requires Si-based dielectric films with a tunable composition and dielectric constant. , In particular, C-containing SiN x films (SiC x N y ) are required for applications such as diffusion barriers, etch stops, and sidewall spacers . The next generation of semiconductor devices further imposes two stringent requirements on the SiC x N y films: conformality >95% over high-aspect-ratio nanostructures and a deposition temperature ≤400 °C.…”