Copper Line Resistance Control and Reliability Improvement by Surface Nitridation of Ti barrier Metal

In this study, we explore the potential of replacing the wetting and diffusion barrier layers in a conventional under bump metallurgy (UBM) structure, underneath flip-chip solder joints, with a buffer TiWN x -bearing Cu film deposited via cosputtering, viz., barrierless Si metallization, to reduce manufacturing, including soldering, costs in microelectronic manufacture. The introduced Cu(TiWN x ) films, after annealing at 700 C for 1 h, exhibit an excellent thermal stability on, and adhesion strength to, barrierless Si substrates, without detectable Cu/Si interfacial interactions and also display a solderability comparable to that of pure Cu. At 200 C, the Cu(TiWN x ) film within an Sn/Cu(TiWN x )/Si structure shows a dissolution rate that is lower than that of pure Cu by at least one order of magnitude, comparable to that of Ni in common solder joints. The Cu(TiWN x ) film thus seems to be a suitable candidate material for, at least, barrierless Si metallization and flip chip soldering.

Section: Fabrication and Analysis Of Cu(tiwn X ) Filmsmentioning

confidence: 99%

Cu(TiWN_x) Film as a Barrierless Buffer Layer for Metallization Applications

Lin¹,

Chuang

Kao

2013

“…Figure 4(a) shows the I-V curves for the MOS capacitors fabricated by depositing pure Cu, Cu(Ge), and Cu(GeN x ) films atop SiO 2 /Si substrates after annealing at 400 °C for 1 h. The annealing temperature is chosen as 400 °C since thermal evaluations are typically performed at this temperature. [30][31][32] When the electric field strength exceeds 2.7 MV/cm, the leakage current for the pure Cu gates in the capacitors increases markedly owing to a large amount of Cu that diffused through SiO 2 during annealing. At 2 MV/cm, the leakage current of the Cu(GeN x ) film (2.09 © 10 ¹10 A/cm 2 ) is lower than those of the Cu(Ge) (1.86 © 10 ¹8 A/cm 2 ), Cu(WN) (4.9 © 10 ¹9 A/cm 2 ), 11) Cu(MnN) (3.83 © 10 ¹10 A/cm 2 ), 8) Cu(Mo) (3.8 © 10 ¹8 A/cm 2 ), 12) and pure Cu (1.6 © 10 ¹7 A/cm 2 ) films, 10) confirming the Cu(GeN x ) film's excellent thermal stability and confirming its role in barrierless metallization.…”

Section: Resultsmentioning

confidence: 99%

A new Cu(GeN_x) alloy film for industrial applications

Lin¹

2014

In this study, a copper alloy [Cu(GeN x )] film is developed for industrial applications by cosputtering Cu and Ge targets on a barrierless Si substrate within a vacuum chamber sparsely filled with N 2 gas. Through extensive tests conducted in this study, the alloy film shows good thermal stability and adhesion to the substrate with no noticeable interactions between the film and the substrate after annealing at 720 °C for 1 h. The new Cu(GeN x ) alloy film also renders adequate wetting for solders, shows good solderability, and has a dissolution rate lower than pure Cu by at least one order of magnitude, in addition to having a comparable consumption rate to Ni. The alloy film seems suitable for industrial applications in, e.g., barrierless Si metallization, interconnect manufacture and, the replacement of the wetting and diffusion layers for flip-chip solder joints in conventional metallurgy.

“…Figure 7(a) shows the I-V curves for MOS capacitors fabricated by depositing pure Cu, Cu(Mn), and Cu(MnN x ) films atop SiO 2 /Si substrates after annealing at 400 C for 1 h. The annealing temperature is selected as 400 C since thermal evaluations are typically performed at this temperature. [20][21][22] When the electric field strength exceeds 2.7 MV/cm, the leakage current for the pure Cu gates in the capacitors increases dramatically owing to a large amount of Cu diffusing through SiO 2 during annealing. At 2 MV/cm, the leakage current of the Cu(MnN x ) film (3:83 Â 10 À10 A/cm 2 ) is lower than that of the Cu(Mn) (1:63 Â 10 À8 A/cm 2 ), Cu(WN) (4:9 Â 10 À9 A/cm 2 ), 7) Cu(Mo) (3:8 Â 10 À8 A/cm 2 ), 8) and pure Cu (1:6 Â 10 À7 A/cm 2 ) films, 6) verifying the Cu(MnN x ) film's outstanding thermal stability and qualifying its role in barrierless metallization.…”

Section: Fabrication and Analysis Of Cu(mnn X ) Filmmentioning

confidence: 99%

A New Copper Alloy Film for Barrierless Si Metallization and Solder Bump Flip-Chip Application

Lin¹

2013

In this study, a copper alloy, Cu(MnN x ), film is developed by cosputtering Cu and Mn on a barrierless Si substrate within an Ar/N 2 gas atmosphere. The resulting alloy film exhibits good thermal stability and adhesion to the substrate with no noticeable interactions between the film and the substrate after annealing at 700 C for 1 h, indicating that the film is thermally stable. The alloy film shall be able to replace both the wetting and diffusion layers for the flip-chip solder joints in conventional under bump metallurgy to reduce the manufacturing cost. We also observe that the Cu(MnN x ) alloy exhibits a solder ability comparable to that of pure Cu and a dissolution rate lower than that of pure Cu by at least one order of magnitude. The alloy's consumption rate is comparable to that of Ni, rendering the alloy a candidate material in both barrierless Si metallization and solder bump flip-chip application. #