Leveler Effect and Oscillatory Behavior during Copper Electroplating

Huang, Qiang; Baker-O'Neal, Brett; Parks, C.; Hopstaken, Marinus; Fluegel, Alexander; Emnet, C.; Arnold, Marco; Mayer, Dieter

doi:10.1149/2.020209jes

Cited by 36 publications

(42 citation statements)

References 16 publications

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“…As imilar effect has been reported by Huang et al for the incorporation of commercial leveler additives. [12] At otal number of 15 maximai nt he SIMS depth profiles (see panel Ci nF igure 3) correlate with the same number of potential oscillations in the potential/time transient curve,a tl east for the low-frequency oscillation. It is, however,n ot possible to precisely reproduce the absoluten umber of maximaa nd minimao ft he SIMS depth profile from the high-frequency deposition process.…”

Section: Film Characterization By Sims Depth Profilingmentioning

confidence: 90%

“…Huang et al reported av ery similarn onlinear instability in galvanostaticC ue lectroplating in the presence of ac ommercial leveler additive used for Damascene applications. [12] The current paper is organized as follows. In the first part, we present two oscillatory Cu platinge xperiments, representing two extremes in the frequency of the potential oscillation [low-frequency (L) and high-frequency (H) limits].T he electrochemicalo scillations are then discussed on the basis of their respective SIMS depth profiles.…”

Section: Introductionmentioning

confidence: 99%

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Combined Secondary Ion Mass Spectrometry Depth Profiling and Focused Ion Beam Analysis of Cu Films Electrodeposited under Oscillatory Conditions

et al. 2015

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Section: Film Characterization By Sims Depth Profilingmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Combined Secondary Ion Mass Spectrometry Depth Profiling and Focused Ion Beam Analysis of Cu Films Electrodeposited under Oscillatory Conditions

et al. 2015

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“…The second possible way of changing the super filling by the leveler is that the presence of leveler in the bulk solution can change the potential bias applied to the wafer, or the potential transients acquired during the first experiment. 33 However, this leveler effect is only present in a longer time scale, typically after about 20 seconds, 33 as compared with the filling time, typically within 5 seconds. The potential response within a few seconds is independent of the presence of leveler and is only determined by the suppressor and accelerator.…”

Section: Resultsmentioning

confidence: 99%

An Electrochemical Method of Suppressor Screening for Cu Plating in Sub-100 nm Lines

Huang¹,

Liu²,

Baker-O'Neal³

2014

J. Electrochem. Soc.

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A two-step transient method was developed to electrochemically screen suppressor molecules toward the applications in Cu plating chemistry for narrow trenches. The first potential transient with full amount of suppressor was acquired to simulate the potential applied on the wafer, which is largely determined by the plating of the field region on the wafer. A second current transient experiment with the potential controlled by the transients acquired in the first experiment is used to mimic the plating at different locations across the wafer. When different fractional amounts of suppressor are injected into the second experiment, the current transients acquired thereof simulate the plating rate in the trench structure. A slower super filling rate at higher plating current was well predicted by the transient method and was confirmed by filling experiments. A good qualitative correlation was also observed between the current transients and the filling performance of different suppressors. Cu electroplating has been one of the critical steps in the Cu interconnect technology, which has been used for over a decade in semiconductor and microelectronic devices.1,2 The Cu electroplating is a so called super-conformal filling or super filling process, where the deposition rate at the bottom of a structure is much faster than the rate at the top of the structure so that the structure is filled void free. These super filling processes generally rely on the organic additives in the plating solution, particularly, the suppressor and accelerator. The additive behavior 3-18 and the associated properties of the plated Cu films [19][20][21][22][23][24][25] have been extensively studied. As the dimensions of the state-of-the-art semiconductor devices scale, advanced plating chemistries are demanded to form the structures defect free.The mechanism of the super conformal filling has been studied extensively. A widely adopted mechanism was proposed by Moffat et al. [9][10][11][12] and West et al., 13 where an accumulation and crowding of the accelerator was proposed to occur on the Cu surface at the bottom of the structure due to a continuous shrinkage of the Cu growth front surface area during plating. This so-called curvature enhanced accelerator coverage (CEAC) hypothesis is in agreement with the observations that the accelerator floats on top of the Cu surface during plating 11 and that the plating rate suppressed by the suppressor is promoted by the accelerator due to a displacement or disruption of the surface passivation film. 12 The CEAC model therefore successfully explains a faster local plating rate at the bottom of the feature, resulting in the super filling. The CEAC mechanism also predicts a bump formation on top of dense patterns of small structures due to the locally high surface coverage of accelerator after the structures are filled. 10,13 In addition, the CEAC mechanism predicts that a pre-treatment of the Cu substrate in a more concentrated accelerator solution can provide a higher initial coverage of accelerator...

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“…Ni was plated with the same chemistry and condition as described above for Ni silicide formation. A typical damascene plating solution 19 for interconnect fabrication was used to plate the Cu grid. While studies with other chemistries showed the damascene plating solution was not necessary, the studies presented in this paper used a same damascene Cu chemistry.…”

Section: Methodsmentioning

confidence: 99%

Light Assisted Electrodeposition and Silicidation of Ni for Silicon Photovoltaic Cell Metallization

Huang¹,

Rao²,

Fisher³

2015

ECS J. Solid State Sci. Technol.

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Light assisted electrodeposition of Ni films was studied on crystalline Si photovoltaic cells. The nucleation, film uniformity and silicidation behaviour were studied at different locations across the busbar and were found to strongly depend on the plating solution, plating current and annealing conditions. The photovoltaic diode can be operated at forward bias or reverse bias during the light assisted electroplating depending on the plating current and light intensity. Suns-Voc of the solar cells was examined at different stages along the process to evaluate the impacts of silicidation on the cell performance. Detailed microscopic analysis was conducted for the metallization stack. The post-silicide degradation in Suns-Voc was correlated with local shunting due to non-optimized silicidation condition. © The Author Solar energy, one of the main types of renewable energy, is critical to help meet the ever-increasing demand for energy from our human society. Among the different solar cells, crystalline silicon solar cells dominate the global solar market. The manufacturing process currently used involves screen-printing for the front metallization using Ag paste. While the screen-printing process has been integrated into the process flow with standard tooling, it typically causes higher wafer breakage and suffers conversion loss due to the lower conductivity, the lower line height-width aspect ratio and the large printing spot size. In addition, the high price of Ag metal drives up the cost of the solar cell and thus delays the break-even point.Replacing the screen-printed Ag with electroplated high aspect ratio Cu lines has been proposed decades ago.1,2 This method has recently gained more and more attention due to the increasing price of Ag and its potentially easy integration with the laser patterning. The selective emitter formed by the in-situ doping during laser patterning [3][4][5] further improves the conversion efficiency of the solar cell.Different Cu metallization schemes involving electroplating have been reported, 6,7 such as electroless deposition of Ni and silicidation, [8][9][10] Cu electrodeposition on printed thin seed layer, 11,12 and electrodeposition of Ni and Cu. 13,14 Among them, most of the schemes involve the formation of Ni silicide either from electroless or electrolytic deposited Ni. The electrolytic deposition process in these reports typically involves light, so called light induced or light assisted electrodeposition. The formation of silicide lowers the contact resistance between the metal and Si and thus improves the solar cell performance.Ni silicidation has been extensively studied for the application in CMOS (complementary metal oxide semiconductor) contacts. 15-17The Ni silicidation starts at as low as about 300• C for metal rich phases, followed by monosilicide phases at around 400• C and silicon rich phases at above 800• C. 15 As far as the authors are aware of, all the studies for CMOS applications were performed on extremely thin Ni or Co films fabricated using vacuum depos...

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Leveler Effect and Oscillatory Behavior during Copper Electroplating

Cited by 36 publications

References 16 publications

Combined Secondary Ion Mass Spectrometry Depth Profiling and Focused Ion Beam Analysis of Cu Films Electrodeposited under Oscillatory Conditions

Combined Secondary Ion Mass Spectrometry Depth Profiling and Focused Ion Beam Analysis of Cu Films Electrodeposited under Oscillatory Conditions

An Electrochemical Method of Suppressor Screening for Cu Plating in Sub-100 nm Lines

Light Assisted Electrodeposition and Silicidation of Ni for Silicon Photovoltaic Cell Metallization

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