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

Abstract

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.

A new Cu(GeNx) alloy film for industrial applications

“…7(a) and 7(b), where (a) represents the results in the no-aging case indicate the result before aging and (b) after aging for 8 days, all at 200 °C. These images also show the thickness of the Cu(GeN x ) buffer (³198 nm) after aging for 8 d, as compared with those of the Cu(TiWN x ) buffer (³14 nm) 7) and Cu(MnN x ) buffer (³187 nm), 8) which further confirms the Cu(GeN x ) buffer layer's stability and to prevent a Cu-Sn reaction.…”

“…[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. The results are consistent with the SIMS results shown in Fig.…”

“…The alloying of Cu with insoluble components has attracted the attraction of many researchers owing to its many for several industrial applications and is crucial in materials science. For example, Cu(RuN x ), films were developed and reported in 2007 and 2010; [5][6][7][8][9][10] previous studies [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] have shown that Cu(ReN) 13) alloy films are thermally stable up to 730 °C. Iijima et al and Dixit et al developed Cu-Mn alloy films that can be applied to the fabrication of interconnects in semiconductor manufacture.…”

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

“…10(a)-10(d), where (a) represents an unaged scenario, and (b) after ageing for 4, (c) 6, and (d) 8 days, all at 200 C. These images also show the thickness of the Cu(MnN x ) buffer ($187 nm) after ageing for 8 d, as compared with that of the Cu(TiWN x ) buffer ($14 nm) reported in previous studies. 24) This further verifies the Cu(MnN x ) buffer layer's stability and its ability to prevent a Cu-Sn reaction. The substrate consumption behavior during the reaction at 200 C is shown in Fig.…”

New Cu(TiIrNx) Alloy Films for Solder Bump Flip-Chip Application

“…To this end, Cu alloys such as Cu(RuN x ) films were developed and were reported in 2007 and 2010. [4][5][6] Barrierless metallization simplifies the manufacturing process for electronic devices, thereby reducing manufacturing cost. Cu alloy films also enhance the thermal stability of Cu when mixed with insoluble components, e.g., W, 7) forming distinct microstructures for better thermal properties.…”