Effect of bis-(3-sodiumsulfopropyl disulfide) byproducts on copper defects after chemical mechanical polishing

Hung, Chi-Cheng; Lee, Wen−Hsi; Hu, Shao-Yu; Chang, Shih-Chieh; Chen, Kei-Wei; Wang, Ying-Lang

doi:10.1116/1.2834679

Cited by 14 publications

(21 citation statements)

References 17 publications

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“…This additive helps to promote the so‐called superfilling or bottom‐up fill of fine features with desired metal properties; however, the precise mechanism of action of SPS is still lacking 16. The main by‐products of SPS (Table 1) are thought to include mono‐oxide of SPS, di‐oxide of SPS, and 1,3‐propanedisulfonic acid (PDS) as oxidation by‐products, and 3‐mercaptopropyl sulfonate (MPS) as a reduction by‐product 17.…”

Section: Introductionmentioning

confidence: 99%

“…A more reliable and quantitative analysis method for SPS and its breakdown products is possible with high‐performance liquid chromatography (HPLC). A few efforts have already been described in the literature for analysis of SPS and its byproducts by HPLC with various detection schemes, such as UV spectroscopy 22, 23, mass spectrometry (MS) 17, and others. However, we are not aware of studies that show an adequate separation of SPS by‐products, unambiguously assign chromatographic peaks, and have detection sensitivity in the nano‐molar range.…”

Section: Introductionmentioning

confidence: 99%

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Chromatography of bis‐(3‐sulfopropyl) disulfide and its breakdown products by HPLC coupled with electrochemical detection

Volov

Mann

Hoenersch

et al. 2011

J of Separation Science

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A chromatographic method for the detection of bis-(3-sulfopropyl) disulfide (SPS), a common additive in acidic copper plating baths, and its breakdown products is demonstrated. The detection scheme involves a combination of solid-phase extraction for sample pre-treatment, C(18) reversed-phase high-performance liquid chromatography column for separation, and electrochemical sensor for detection of all non-fully oxidized sulfur-containing compounds. We were able to achieve an effective separation and accurately assign chromatographic peaks to all detectable species. Owing to a high sensitivity of the utilized electrochemical detector, detection in low parts per billion range was possible. This can prove crucial for plating bath control, since minute amounts of certain by-products significantly affect the bath performance.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chromatography of bis‐(3‐sulfopropyl) disulfide and its breakdown products by HPLC coupled with electrochemical detection

Volov

Mann

Hoenersch

et al. 2011

J of Separation Science

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“…25 However, organic additives decompose through chemical/ electrochemical side reactions during operation of the plating solution [26][27][28][29][30][31][32][33][34][35] or even under open circuit condition, 36,37 which leads to degradation of the plating solution. Decomposition of SPS during * Electrochemical Society Active Member.…”

Section: Mpsmentioning

confidence: 99%

High Accuracy Concentration Analysis of Accelerator Components in Acidic Cu Superfilling Bath

Choe

Kim

et al. 2015

J. Electrochem. Soc.

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We have devised a modified cyclic voltammetry stripping (CVS) method to measure the concentrations of bis-(sulfopropyl) disulfide (SPS) and 3-mercapto-1-propane sulfonate (MPS) in Cu plating solutions. Though MPS, a breakdown product of SPS, enhances the Cu deposition rate on flat electrodes, it is not a superfilling-capable accelerator for the damascene structure, unlike SPS. Therefore, accurate measurement of SPS in damascene Cu plating baths is important. However, enhancement of the Cu deposition rate by MPS interferes with the electrochemical signal of SPS, leading to a significant error when using the modified linear approximation technique (MLAT)-CVS analysis method. To evaluate their concentrations individually, a two-step CVS analysis was performed in which the total accelerator concentration ([SPS] + 1/2[MPS]) and conversion ratio were separately determined. All MPS species in the bath were oxidized to SPS by controlling the plating solution pH. Subsequent MLAT-CVS analysis successfully revealed the total accelerator concentration in the Cu plating solution. Individual SPS and MPS concentrations were thereby calculated using the conversion ratio evaluated from the difference in their relative accelerating abilities. This modified method enabled determination of the SPS concentration with <10% error, suggesting a reliable and high accuracy tool to predict pattern filling capabilities of plating solutions. Owing to the merits of high throughput, low process cost, and good film quality, Cu electroplating has a wide application, from traditional Cu foil production to state-of-the-art semiconductor metallization processes. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The Cu plating solution typically contains small amounts of organic additives, 1-16 which enhance the uniformity, 13 brightness, 14 and mechanical properties of the Cu film. 15 In addition, for particular application to damascene Cu plating, the additives enable bottom-up filling at trenches or vias by controlling the relative deposition rates of Cu at the top and bottom of the features.1-12 For this application, the organic additives are grouped as the accelerator, suppressor, and leveler based on their electrochemical behaviors and their roles in pattern filling.One of the most widely used accelerators is bis-(sulfopropyl) disulfide (SPS), a dimer of 3-mercapto-1-propane sulfonate (MPS). Acceleration by SPS in Cu superfilling has been explained by the competitive adsorption theory [17][18][19][20][21] or by the catalytic action caused by the reduction of cupric ions. 22,23 In the competitive adsorption theory, acceleration is regarded as a recovery of the deposition rate previously suppressed by the polyethylene glycol (PEG)-Cl inhibition layer, and recovery occurs through the displacement of the PEG-Cl layer with SPS.17-19 A recent study revealed that the acceleration is a result of the dissociative adsorption of SPS with displacement of the well-ordered Cl − layer. 20,21 MPS, a dissociated product of SPS, reconverts to SPS with re...

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“…Various methods have been developed for monitoring the additive concentrations, including electrochemical techniques such as cyclic voltammetry stripping (CVS) and cyclic pulse voltammetry stripping (CPVS), 31,[45][46][47] and spectroscopic methods such as nuclear magnetic resonance (NMR), [30][31][32][33] UV-visible spectroscopy, 34,35 mass spectroscopy, [36][37][38] and chromatography. 39,40 Among these, CVS and CPVS have been regarded as the most powerful tools because of their simplicity and sensitivity.…”

Section: +mentioning

confidence: 99%

“…29 During electrolysis, the concentrations of the organic additives gradually decrease due to the physical incorporation of the additives in the Cu deposit and chemical/electrochemical decomposition reactions. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Since the properties of the plated films strongly depend on the concentrations of the organic additives, the performance of the plating solution gradually degrades upon continued use of the plating solution.…”

Section: +mentioning

confidence: 99%

Accuracy Improvement in Cyclic Voltammetry Stripping Analysis of Thiourea Concentration in Copper Plating Baths

Choe

Kim

et al. 2015

J. Electrochem. Soc.

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Cyclic voltammetry stripping (CVS) has been regarded as a powerful tool for monitoring the concentrations of organic additives in plating baths. In this study, the dilution titration (DT) method of CVS was modified to improve the measurement accuracy of thiourea (TU) concentrations in Cu plating baths. The conventional DT-CVS method cannot guarantee high accuracy because the electrochemical behavior of TU is concentration and potential dependent, which can cause disturbances in the response signals. In this study, by adding polyethylene glycol (PEG) as an organic additive, the undesirable electrochemical behavior of TU was suppressed and the accuracy of DT-CVS was greatly improved. Using the improved method, the concentrations of TU and its derivatives in the plating bath were measured. The errors between the real and measured concentrations were reduced from 15.0%, 36.0%, and 15.0% using the conventional DT-CVS method to within 3.00%, 6.00%, and 6.00% for TU, N-ethyl thiourea, and N ,N-diethyl thiourea, respectively, using the improved method. Organic additives are important constituents of the electroplating baths owing to their ability to control the morphology and the film properties of the plated material.1-17 The organic additives are typically grouped into suppressors, accelerators, and levelers, based on their roles and functionality.1-17 Examples of organic additives in electroplating baths include bis(3-sulfopropyl) disulfide, polyethylene glycol (PEG), janus green b (JGB), polyethylene imine (PEI), 1,2,3-benzotriazole (BTA), and thiourea (TU). 1,2,[6][7][8][9][10][11][12][13][18][19][20][21][22][23][24][25][26][27][28][29] TU is a common additive in Cu and Ag electrodeposition baths and induces leveling and grain refining properties.18-26 TU has been used as an additive either solely or in combination with Cl − (TU-Cl − ) in baths used for electrodeposition processes involving various current/potential waveforms such as direct current, pulse-, or pulsereverse waveforms. 20,21,23,24 Various applications of TU as an additive have been studied, including the formation of the Cu twin, Ag superfilling, and the fabrication of CuS nanowire structures. 18,19,[23][24][25][26] TU is known to form thiolate complexes such as [Cu-(TU) ions. [27][28][29] Owing to the various derivatives and their different electrochemical responses, TU shows unique electrochemical behavior unlike typical suppressors or levelers. Although TU commonly reduces the Cu deposition rate, it often acts in an opposite role as an accelerator under specific conditions such as low concentrations and low overpotentials. [27][28][29] Several mechanisms explaining the accelerating effect of TU have been proposed. [27][28][29] Generally, the reduction of Cu 2+ occurs in two steps, namely the reduction of Cu 2+ to Cu + , followed by the reduction of Cu + to Cu 0 . The first step has been known to be the rate-determining step. In the presence of TU, however, additional reactions occur, as described in Eq. 1. 29 They explained that the chain reaction...

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Effect of bis-(3-sodiumsulfopropyl disulfide) byproducts on copper defects after chemical mechanical polishing

Cited by 14 publications

References 17 publications

Chromatography of bis‐(3‐sulfopropyl) disulfide and its breakdown products by HPLC coupled with electrochemical detection

Chromatography of bis‐(3‐sulfopropyl) disulfide and its breakdown products by HPLC coupled with electrochemical detection

High Accuracy Concentration Analysis of Accelerator Components in Acidic Cu Superfilling Bath

Accuracy Improvement in Cyclic Voltammetry Stripping Analysis of Thiourea Concentration in Copper Plating Baths

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