A 2-nm-Thick Mn Oxide on a Nitrogen-Stuffed Porous Carbon-Doped Organosilica as a Barrier of Cu Films

Abstract

An ultrathin (e.g., ≤ 2 nm) barrier is needed for fabricating Cu interconnects associated with porous low-k (p-SiOCH) dielectrics with a high aspect ratio trenches/vias in the ultra large scale integrated circuits. To implement successfully the ultrathin Mn oxide barrier on the p-SiOCH dielectric for Cu interconnection, understanding is needed of how the Mn oxide is formed. This study investigated a 2-nm-thick Mn oxide film, deposited by sputtering with a biased-filter intermediating, as the barrier layer to prevent Cu from diffusion. Phase formation of the as-deposited Mn oxide was examined by X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy to confirm the formation of Mn 2 O 3 . The experimental results indicated that the formation of Mn 2 O 3 barrier is highly effective in preventing the Cu film from diffusion and agglomeration. Thermal stability of the Cu film increased up to 550 • C, 250 • C greater than the p-SiOCH dielectric without the Mn 2 O 3 film, when combining the nitrogen-stuffed treatment on the p-SiOCH dielectric and annealed the Mn 2 O 3 before the Cu deposition. The structures of Mn 2 O 3 barrier and p-SiOCH dielectric after nitrogen-stuffing treatments were analyzed to evaluate their applicability in Cu interconnects.

Electrical Characteristics and Reliability of Nitrogen-Stuffed Porous Low-k SiOCH/Mn2O3-xN/Cu Integration

“…After a nitrogen-stuffing treatment at 450 °C/4 atmosphere for 5 min, the accumulation capacitance slightly increased to 2.317 × 10 −4 F/m 2 , leading to an increase of k value to 2.618. Notably, the high-pressure nitrogen treatment results in the stuffing of the pores within the p-SiOCH film [denoted as p-SiOCH(N)] with physisorbed nitrogen atoms (or molecules) [16], thus rendering only a 2.26% increase in k value. After the sputter deposition of a 2 nm-thick Mn 2 O 3 barrier, a large increase in accumulation capacitance of the p-SiOCH(N) film was measured, associated with a marked increase of k value to 2.914 (11.30%).…”

“…Subsequently, a 2 nm-thick layer of Mn 2 O 3 (transmission electron microscopy; Hitachi HD-2300A, Hitachi–Science & Technology, Tokyo, Japanese) was deposited onto p-SiOCH(N) through a shadow mask by sputtering a Mn target under a controlled Ar/O 2 oxidative atmosphere. The resultant sample, denoted as Mn 2 O 3 /p-SiOCH(N)/Si, was subjected to stabilization annealing at 450 °C in an Ar/H 2 (5%) forming gas for 60 min, converting the Mn 2 O 3 to Mn 2 O 3−x N [16]. Finally, a 50 nm-thick Cu film (alpha-step 200 profilometer, KLA/Tencor, Austin, TX, USA) was thermally evaporated onto the stacked sample also through a shadow mask.…”

“…In light of the aforementioned studies of metal-based barriers, we have recently proposed a novel barrier process for Cu metallization [16] by firstly performing high-pressure nitrogen stuffing of a porous low- k SiOCH dielectric. Then, a 2 nm-thick Mn oxide film was deposited in a controlled (oxygen-containing) sputtering gas.…”

(3-Aminopropyl)trimethoxysilane Self-Assembled Monolayer as Barrier of Porous SiOCH for Electroless Cu Metallization: Optimizations of SiOCH Hydroxylation and Monolayer Functionalization

“…This prevented the porous SiOCH from vacuum plasma damage during sputtering. 24 A 200 nm thick Al film was sputterdeposited on the backside of the Si as the bottom electrode.…”

Electrical Characteristics and Reliability of Nitrogen-Stuffed Porous Low-<em>k</em> SiOCH/ Mn₂O_3-xN/Cu Integration

“…The low dielectric-constant (k) material used in this study was porous SiOCH (abbreviated hereafter as p-SiOCH), which was deposited on a p-type (100) Si wafer by an Applied Materials plasma-enhanced chemical vapor deposition system using diethoxymethylsilane (DEMS), oxygen (O2), and alpha-terpinene (ATRP) porogen as precursors [17]. The thickness and k value of p-SiOCH dielectric films were ~100 nm and 2.560, respectively.…”