TDDB improvement in Cu metallization under bias stress

Abstract

Time-dependent dielectric breakdown (TDDB) between Cu interconnects is investigated. TDDB lifetime strongly depends on the surface condition of the Cu interconnect and surrounding pTEOS. A NH3-plamsa treatment prior to cap-pSiN deposition on Cu interconnect improved the dielectric breakdown lifetime ( G~) over cap-pSiN deposition only. The plasma treatment also has the beneficial effect of suppressing wiring resistance increase during pSiN deposition. These results suggest that CuO reduction to Cu, and CUN formation at the Cu interconnect surface prevents Cu silicidation during pSiN deposition. Futhermore, SiN formation and bond termination by hydrogen radicals at the pTEOS surface diminish surface defects, such as dangling bonds. TDDB lifetime also strongly depends on the Cu CMP process, in which mechanical damage of the Si02 surface during CMP process degrades TDDB. Adoption of a mechanical damage free slurry or a post-CMP HF treatment to remove the damaged layer from the surface improves TDDB .

Disconnection of NiSi shared contact and its correction using NH<inf>3</inf> soak treatment in Ti/TiN barrier metallization

“…Drawbacks of NH 3 plasma treatment NH 3 plasma treatment is widely used to deoxidize native oxides and to nitridize the surface on copper interconnects [10], [11]. However, we show that NH 3 plasma treatment, ether before or after titanium deposition, is not appropriate for contact metallization due to two drawbacks: plasma-induced damage of the gate oxide and excessive nitridation of Ti/TiN.…”

Interface Reliability Assessments for Copper/Low-k Products

“…For example, use of a triangular voltage sweep (TVS) method to characterize Cu ion migration under applied field in dual-damascene via test structures indicated that a low-k/dielectric cap interface may be a fast diffusive pathway [59]. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis showed that NH -plasma was essential in forming a fully nitrided Cu surface prior to SiN barrier capping, reducing and thus eliminating any residual Cu oxide on the Cu trench surface [52], [60].…”

“…Furthermore, the test conditions and/or test structures used in evaluating a given metric such as TDDB vary. However, with the advent of a long-term reliability study using TDDB [52], [54], some notions of what constitutes intrinsic reliability in dual-damascene BEOL dielectrics are emerging.…”

“…In particular, the thermochemical model or "E-model" [74] has been used either explicitly or implicitly to describe the TDDB aspects of BEOL dielectric reliability [52], [54]. In the thermochemical model, TDDB lifetime dependence is shown to be exponentially dependent on the applied field and a "field acceleration parameter" at a given temperature as shown in (2): (2) where is the time to dielectric breakdown, is the enthalpy of activation, is the field acceleration parameter, is the electric field within the dielectric, and is a proportionality constant.…”

Copper Wires for High Speed Logic LSI Prepared by Low Pressure Long Throw Sputtering Method

“…[1][2][3] Compared to the Al-alloy, which is easy to perform dry etching process, it is very difficult to manage the Cu dry etching. To realize the Cu interconnect, damascene process with chemical mechanical polishing (CMP) of Cu is widely studied.…”