Wafer surface is usually contaminated by organic residues, such as benzotriazole(BTA), after chemical mechanical planarization (CMP). Due to the reason that these organic residuals need to be removed ...during the post-CMP cleaning process as well as keep the copper corrosion prevented, it is critically important for some large scale industrial applications to develop an effective and low-cost cleaning solution, which will remove the organic residuals and inhibiting corrosion of copper surface. In this work, the effect of surfactant based on alkaline chelating agent was investigated for BTA removal and copper corrosion during post-CMP cleaning. BTA removal was characterized using contact angle measurements and X-ray photoelectron spectroscopy (XPS) analysis. The degree of corrosion of Cu surface was characterized by scanning electron microscope (SEM) and electrochemical techniques. The Cu surface quality after cleaning was characterized by atomic force microscopy (AFM). The defect maps of the 300 mm Cu patterned wafer surface after cleaning were also collected. The experimental results demonstrate that surfactant in the cleaning solution can effectively inhibit the Cu surface corrosion with a lower surface roughness and simultaneously facilitate the removal of BTA residues. The related cleaning mechanism has been studied and proposed based on our experimental results.
Silicon wafers have been widely used as substrate in the Giga large-scale integration (GLSI). Silicon chemical mechanical polishing (CMP) factors are very important for the polished silicon surface ...state, because they play an important role in the quality and yield of devices. The effect of CMP factors on silicon substrate removal rate and surface quality used for advanced technology nodes integrated circuit (IC) manufacturing was the focus of this study. In particular, the effect of pH, temperature, and abrasive concentration on silicon CMP were investigated. The alkaline slurry used in the experiments was a non-hydrogen peroxide based system containing a novel type chelating agent and a surfactant. The pH experiments showed that the silicon removal rate depends on the slurry pH, surface roughness and haze are decreasing with the increase of the slurry pH. The temperature and abrasive concentration experiments proved that the polishing temperature and the abrasive concentration have some effect on silicon removal rate, surface roughness, and haze. The silicon removal rate increases with the increase of the abrasive concentration, while the surface roughness and haze decrease; moreover, with the increase of the polishing temperature, the silicon removal rate, surface roughness, and haze increase. Silicon CMP is a combination of mechanical and chemical processes, which shows that the increase in both the mechanical and chemical effects can contribute to the increase in the silicon removal rate. Furthermore, the surface quality (roughness and haze) depends on the mechanical and chemical effects; the increase in the chemical effect is favorable but that in the mechanical effect is harmful to the surface quality. The results obtained facilitate the study of silicon CMP and other materials.
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•Haze is quantitatively collected on full wafer scale with high throughput.•This paper mainly studied the factors affect on silicon CMP which plays an important role for advanced IC manufacturing.•A good silicon surface can be obtained by increasing chemical effect or decreasing mechanical effect within a certain scope.•The alkaline slurry was a non-hydrogen peroxide based system containing a novel type chelating agent and a surfactant.
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► We have proposed a novel alkaline slurry without inhibitors for barrier CMP. ► The slurry provides lower surface roughness values and good surface quality. ► The slurry provides a ...good planarization performance. ► The slurry can be useful for barrier CMP.
Chemical mechanical planarization (CMP) is a vital process for the fabrication of advanced copper multilevel interconnects schemes. The formidable challenge in barrier CMP is that the copper lines suffer from dishing and erosion. There have been several efforts to reduce both dishing and erosion by extensive experimental investigations. However, most of the slurries applied in CMP processes are acidic and containing some kinds of inhibitors. In this paper, we have proposed a novel alkaline slurry without any inhibitors (namely slurry A) for barrier CMP and investigated its CMP performance by comparison with a commercial slurry (namely slurry B). The CMP performance is evaluated in terms of surface roughness, dishing and erosion values. The CMP results obtained from the roughness maps of copper blanket wafers show that the Cu films polished by slurry A has lower surface roughness values and good surface quality than that polished by slurry B. CMP data obtained from patterned wafers show that the amounts of dishing increases with the increment of line width, while the erosion has a slight decrease with increasing line width, the tendency is apparently the same by using the two different slurries, but slurry A provides a lower dishing and erosion values. The root mean square (RMS) roughness within 10×10μm2 area of copper lines after being polished by slurry A and slurry B is 0.125 and 0.225nm, respectively. By comparison, the alkaline barrier slurry has a good planarization performance and can be useful for barrier CMP.
•A novel corrosion inhibitor TT-LYK is proposed.•The inhibition mechanism of TT-LYK is compared with 1,2,4-triazole by many methods.•Surface roughness is lower with the increase of inhibition ...intensity of inhibitors.•Under mixed effect of two inhibitors, the inhibition effect is effectively improved.
As the most basic interconnection metallic material, copper (Cu) has been widely used in giant-large scale integrated circuits (GLSI). Corrosion inhibitors always play a crucial role in the Cu chemical mechanical polishing (CMP) process. The passivation of hydrogen peroxide (H2O2) alone is too weak to adequately protect against chemical corrosion on the surface of Cu film, thus, it is necessary to add corrosion inhibitors to the slurry. As a representative corrosion inhibitor, 1, 2, 4-triazole was compared with a novel corrosion inhibitor known as TT-LYK (ethanol, 2, 2′-(methyl-1H-benzotriazol-1-yl) methyl imino bis-), and their mixed inhibitor was studied in this paper. Different analytical methods such as the potentiodynamic polarization test, physical appearance phenomenon analysis, contact angle measurement and dynamic polishing experiment were used to compare their inhibition properties, and the fitting of different adsorption isotherms and static erosion tests were used to clarify the adsorption types and passivation processes respectively. The results indicated that both TT-LYK and 1, 2, 4-triazole achieved the goal of inhibiting Cu surface corrosion, but the inhibition effect of TT-LYK was slightly weaker at the same mass fraction. The corrosion protection of the two inhibitors is mainly attributable to the presence of organic inhibitor molecules on the surface of Cu by chemisorption and physisorption simultaneously. The passivation processes of both can be divided into two steps. First, the direct growth of the Cu-inhibitor passivation film occurs, followed by the redeposition of the Cu-inhibitor complex. From the results of electrochemical experiments, it can be concluded that the structure of the thin passivation film growing on the Cu surface varies with the inhibitor, and the composition of the passivation film was investigated by XPS and Raman spectrum analysis. At the same time, the surface roughness after polishing was found to decrease with the increase in inhibition effect of the inhibitors. According to the inhibition characteristics of these two inhibitors, a mixed corrosion inhibitor (TT-LYK and 1, 2, 4-triazole) was proposed in this study. Under the synergistic inhibition action, better inhibition effect and surface quality for Cu CMP were obtained. This outcome may be ascribed to the variation in the structure and density of the passivation film.
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•Sarcosine is proposed as a critical chemical additive in Cu film slurries.•The complexing mechanisms of sarcosine and Cu are revealed by many tests.•The introduction of sarcosine can ...improve the polishing performance of the Cu CMP.
The planarization property of slurry is a crucial factor in evaluating the quality of the copper (Cu) film chemical mechanical polishing (CMP) process. Various chemical additives of amino acids have been widely used in semiconductor and microelectronics industries to develop novel CMP slurries owing to their pollution-free and high-performance characteristics. In this paper, sarcosine was served as a crucial chemical additive in Cu film slurries. Through electrochemical measurements, X-ray photoelectron spectroscopy, Ultraviolet–visible, and Raman spectra tests, it was revealed that sarcosine could react with cupric ions in a ratio of 4:1 to form a stable water-soluble Cu-sarcosine complex, which can accelerate the chemical dissolution of Cu surface during CMP process, and it was also found that the complexing effect was relatively weak. Moreover, various tests on Cu wafers showed that high Cu removal rate (RR), low Cu static etching rate (SER), and ideal surface quality could be realized when sarcosine was used as an auxiliary complexing agent in glycine-based Cu slurries. The purpose of such a study is to find an environmentally friendly chemical additive that can improve the performance of slurry in the manufacturing process of Cu film and other materials used in integrated circuits.
Chemical mechanical polishing (CMP) has been proved to be one of the most important methods to achieve atomic ultra-smooth surface, and it becomes widely used as global planarization techniques. ...There are some influence factors for CMP processing quality, and abrasive in the slurry is one of the key ones. In order to improve the removal rate and surface quality of sapphire substrate, a new-type MgO doped colloidal silica abrasive was studied Based on the basic principle of chemical thermodynamics, the HSC software was used to analyze the tendency of reactions between MgO doped colloidal silica abrasive and sapphire and between H2O and sapphire to generate solid solutions, compounds and hydrates on the sapphire surface. From the CMP experiment results of a-, r- and c-plane sapphire, it indicated that higher material removal rate (MRR) and lower surface roughness (Sq) were obtained with the slurry containing MgO doped colloidal SiO2 abrasive instead of containing pure SiO2 abrasive under the same conditions. In addition, the action mechanism of MgO doped colloidal SiO2 abrasive on sapphire substrate CMP was studied. From the analyzing result of X-ray photoelectron spectroscopy (XPS), it deduced solid-chemical reaction between sapphire surface and MgO doped colloidal silica abrasive was occurred and Al2Si2O7·2H2O, MgAl2O4 and Al2SiO5 were generated, which can promote chemical effects during CMP and lead to the increase of MRR. Such results have certain guiding significance to practical production.
As sapphire device performance continues to improve, greater challenges are posed to the chemical mechanical polishing (CMP) of sapphire, with its high degree of hardness and brittleness. M-plane ...sapphire substrates are not widely used because they are more difficult to process, despite having higher luminous efficiency than C-plane substrates. In this study, the effect of three hydroxyl carboxylates, namely potassium tartrate (PT), potassium citrate (Cit) and sodium gluconate (Gluc), as complexing agents on the CMP of M-plane sapphire was investigated to obtain a high material removal rate (MRR) and low root mean square surface roughness (Sq). First, the chemical reactivities of the three complexing agents were predicted with Material Studio (MS) software. The predicted results showed that the complexing ability of the three complexing agents was greatest for Gluc, followed by Cit, with PT having the least complexing ability. Experimental results confirmed that Gluc was the optimal complexing agent for the M-plane sapphire CMP. The mechanism of action during CMP was revealed by X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR). The results showed that the Al(OH)4‒ ions produced by the sapphire were complexed by Gluc to form the soluble complex Al(OH)4‒/Gluc‒. At the same time, a solid phase reaction also occurred between the M-plane sapphire, SiO2, and water during CMP, and Al2Si2O7∙2H2O was generated. After polishing with the optimized slurry, the M-plane MRR was improved to 5.358 μm/h, a 50% improvement compared with the reference slurry, and the Sq decreased from 0.345 nm to 0.172 nm. These findings provide important guidance for the development of high-performance sapphire devices.
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As a natural macromolecule organic compound, chitosan (CTS, (C6H11NO4)n) was used as a green additive in low-tech node copper (Cu) chemical mechanical polishing (CMP), which has many ...functions and can improve the performance of Cu CMP in some aspects. Firstly, CTS has strong bactericidal properties under neutral or acidic conditions, so it can be used as a fungicide. Besides, CTS molecules have free amino and hydroxyl groups, which can coordinate with metal ions. At pH = 10.00, Ultraviolet-visible (UV–vis) and X-ray photoelectron spectroscopy (XPS) measurements were used to analyze the reaction mechanism of Cu ions and CTS. The results showed that there was a complexation reaction between Cu ions and CTS, and Cu-CTS complexes with parallel bridge structure was formed. In addition, CTS can also be applied to the field of corrosion inhibition of metals for the forming of a passive protective film on the surface of metals to prevent further corrosion within a certain concentration range. Using this property, CTS was introduced into Cu film CMP to improve the removal rate selectivity of Cu to barrier materials cobalt (Co) and ruthenium (Ru) in low-tech node. Specifically, there was a synergistic effect between fatty alcohol polyoxyethylene ether (JFCE, C12H25O.(C2H4O)n) and CTS. With the existence of JFCE, the complexation or inhibition effect of CTS can be improved. Finally, with the introduction of CTS, a lower surface roughness after CMP can be obtained. Therefore, it can be concluded that the green additive CTS with multiple roles can be introduced to the slurries of Cu and other materials used in integrated circuits.
The adsorption models of BTA and TAZ on Co (111) surface in aqueous phase were established by Mont Carlo simulation. Nyquist plots of cobalt inhibitors with different concentrations were simulated by ...EIS measurements.
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•Quantum chemical parameters of BTA and TAZ were evaluated by DFT theory.•N atoms of BTA and TAZ are the coordination sites of the inhibitors.•Adsorption energy of BTA and TAZ in gaseous and aqueous phases on Co(111) surface was calculated by Mont Carlo simulation.•Inhibition efficiency of BTA and TAZ was calculated by electrochemical experiments.
In this study, the corrosion inhibition effects of benzotriazole (BTA) and 1,2,4-triazole (TAZ) at molecular level were evaluated by quantum chemical method. Density Functional Theory (DFT) at BLYP/3.5DNP level and Monte Carlo simulation were performed to analyze the adsorption mechanism of inhibitors on cobalt surface. The electronic parameters of BTA and TAZ were calculated, and their inhibitory effects were investigated by chemical reactivity parameters, respectively. The reactive centers were analyzed based on Fukui functions, indicating that the N atoms are the coordination sites of the inhibitors. Besides, atom densities of different crystal orientations of cobalt were calculated, and the densest Co (111) surface was selected by Monte Carlo simulations for calculation. Under the circumstance of gaseous and aqueous phases, the adsorption models of BTA and TAZ were established. Also, the interaction energy between inhibitors and cobalt was calculated. The results of potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) are consistent with the theoretical calculations. The inhibitory effect of BTA on cobalt surface is greater than that of TAZ. This information helps to gain further insight about corrosion system.
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•Combination of experiments and DFT calculations.•Triazole derivatives are eco-friendly and sustainable inhibitors for metal.•Effect of various derivative groups on inhibition ...efficiency.•Multi-angle study of molecular activity and adsorption behavior on Cu surface.•Provide reference for the selection of organic inhibitors for multiple metals.
The impact of triazole derivative groups on corrosion inhibition performance of copper (Cu) film is studied by using 3-amino-1,2,4-triazole-5-carboxylicacid (ATA-O), 1H-1,2,4-triazole-3,5-diamine (ATA-N) and 3-amino-5-mercapto-1,2,4-triazole (ATA-S) as environment-friendly inhibitors. Electrochemical analysis showed that anti-corrosion passivation layer is formed on Cu surface after adding inhibitors with high inhibition efficiency of 54 %, 87 % and 98 % respectively, and improve the surface quality which is verified by atomic force microscope (AFM) and scanning electron microscopy (SEM) tests. Such results are consisted with static etch experiments. The mechanism of corrosion inhibition was revealed by theoretical calculation, which prove that the lone electron pair in empty orbitals of the O, N, S atoms on inhibitors hybridize with the Cu-d orbital to form covalent bonds and enhance the adsorption passivation action. Such study dissects the reasons for the potent inhibitory effect of triazole derivatives at the atomic level, and provides new method for efficient selection of inhibitors.
