Static Etch Rate Research Articles

Corrosion inhibitors in H2O2 system slurry for Ru based barrier layer Cu interconnect chemical mechanical polishing and optimization

Ruthenium (Ru) has the advantages of low resistivity, high thermal stability, and good adhesion and wettability, making it an important solution for breaking through the 14 nm process as a new barrier layer material for multilayer copper interconnect. The purpose of copper (Cu) interconnect Ru-based barrier layer chemical mechanical polishing (CMP) is to obtain a highly flat surface, which not only includes the ideal Ru removal rate and selectivity of the Cu/Ru removal rate, but also inhibition of Cu corrosion. In this article, the corrosion inhibition mechanism of environmentally friendly and highly water-soluble inhibitor 5-methylthio-1 H-tetrazole (MTT) on Cu was studied. The inhibitory effect of MTT on Cu was analyzed through static etching rate testing, electrochemical experiments, and surface characterization. A systematic test was conducted on the planarization performance of the optimized polishing slurry. The corrosion inhibition mechanism of MTT on Cu was revealed through quantum chemical calculations and XPS testing. The experimental results show that the corrosion inhibitor MTT can effectively improve the surface quality of Cu. Quantum chemical calculations and experimental results indicate that MTT can be adsorbed on the surface of Cu through both physical and chemical methods, forming a dense passivation film, thereby inhibiting the corrosion of Cu. The optimized ratio of Ru-based barrier layer CMP polishing slurry was 5 wt% SiO2, 0.15 wt% H2O2, 20 mM ethylenediamine (EDA), 5 mM K4Fe(CN)6, and 2000 ppm MTT, resulted in the Cu/Ru removal rate selectivity of 1:1.18 and the Cu/Ru corrosion potential difference of 3 mV. The average correction values for dishing and erosion on the test pattern wafer of the Ru barrier layer were 355 Å and 280 Å, respectively. The results of this study indicate that MTT is an effective copper corrosion inhibitor in alkaline H2O2-based polishing slurry, providing meaningful references for Ru-based barrier layer copper interconnect CMP.

Experimental and Computational Investigation of Salicylhydroxamic Acid as a Corrosion Inhibitor for Copper in Alkaline Solutions

Inhibitors, as indispensable components in chemical mechanical polishing (CMP) slurries, have a significant impact on inhibiting copper (Cu) corrosion and enhancing post-polishing surface quality. However, one of the major challenges in CMP lies in unraveling the microscopic corrosion inhibition mechanism of Cu. This work focuses on investigating the impact of an inhibitor, salicylhydroxamic acid (SHA), on the static etching rate (SER), electrochemical parameters, and surface morphology of Cu. The experimental findings demonstrate that SHA significantly decreases the SER and corrosion current density of Cu, while notably improving the Cu surface quality. The corrosion inhibition mechanisms of SHA on Cu are revealed through adsorption isotherm models, contact angle analysis, electrochemical impedance spectroscopy, and computational chemistry method. The benzene ring, oxime group, and O1 atom of SHA exhibit significant chemical reactivity, facilitating the preferential adsorption of SHA on Cu in a parallel orientation, thereby forming a hydrophobic protective film on the Cu surface. This process hinders the interaction between corrosive solutions and Cu, therefore SHA exhibits excellent corrosion inhibition performance on Cu. These findings hold great importance in gaining a deeper comprehension of the corrosion inhibition process of Cu, and provide guidance for designing more efficient inhibitors.

A novel water-in-deep eutectic solvent microemulsions for chemical polishing of single crystal KDP

Microemulsion (ME) has been investigated as a chemical polishing (CP) fluid for effective polishing of single crystal potassium dihydrogen phosphate (KDP), perfectly avoiding the generation of mechanical stress. In this work, a water-in-deep eutectic solvent ME was proposed as the polishing fluid for CP of single crystal KDP. Deep eutectic solvent (DES) is formulated using n-octanol as hydrogen bond donor and methyltrioctylammonium chloride (MTOAC) as hydrogen bond acceptor, with a mass ratio of 2:1. The ME was prepared by mixing DES as the oil phase (12.5 %, wt.), a hydrochloric acid solution as the water phase (12.5 %, wt.), and isopropanol as the cosolvent (75 %, wt.), without adding any other surfactants. The properties of the ME were characterized by conductivity measurements and ultraviolet (UV) spectroscopy. The reactivity of ME with KDP was measured by the conductivity method, and it was higher at low pH values. A hydrochloric acid solution with a pH of 3 was selected as aqueous phase, considering its effects on particle size, salt loading, and static etching rate. The water content affects the polarity of ME and the final water content was determined to be 12.5 % to ensure high polarity of ME. The surface quality of the KDP crystals before and after polishing was examined using grazing incidence X-ray diffraction (GIXRD) analysis. The average roughness of the KDP crystal surface was decreased from 1.96 nm to 1.43 nm, and the root-mean-square (RMS) roughness was reduced from 2.81 nm to 1.86 nm, demonstrating a significant polishing effect. Finally, the polishing mechanism was elucidated in terms of the irreversible chemical reaction between the active components in the microemulsion and the KDP crystals.

Effects of Ceria Abrasives on the Chemical Mechanical Polishing of Molybdenum Film with Alkaline H2O2 Slurries

Abstract The impact of ceria abrasives on the chemical mechanical polishing (CMP) of molybdenum (Mo) films was examined in alkaline slurries utilizing H2O2 as an oxidizer and ceria abrasives. The static etching rate (SER) decreased after the addition of ceria abrasives to the alkaline H2O2-based slurry, while the removal rate (RR) increased except for that of the slurry at pH 9. At pH 9, following the etching of the Mo film in an H2O2 solution with ceria, the surface became coated with MoO3 and Ce2Mo4O15 species. These species originated from the interaction between ceria, H2O2, and molybdic acid. The Ce2Mo4O15 particles envelop the MoO3 surface, thereby preventing the etching of loose MoO3 and hindering further oxidation of Mo to MoO3. This process effectively reduces the RR of Mo. Utilizing ceria slurries at appropriate pH values facilitates achieving a smooth surface with a reasonable RR.

The corrosion inhibition performance and mechanism of α-benzoin oxime on copper: A comprehensive study of experiments and DFT calculations

Copper corrosion poses a significant challenge to process stability and chip quality in the field of integrated circuit manufacturing. This study comprehensively explored the corrosion inhibition performance of α-benzoin oxime (bzoxH2) on copper, by employing a combination of experimental methods and computational chemistry. First, after the addition of 0.1 mM bzoxH2, the static etching rate and surface roughness of copper were decreased to 7 Å·min−1 and 1.36 nm, respectively, which indicated that bzoxH2 could reduce the corrosion rate of copper and improve its surface quality. Subsequently, electrochemical behavior analysis showed that the addition of 0.1 mM bzoxH2 resulted in an increase in open circuit potential to 0.185 V, a decrease in corrosion current density to 2.33 µA·cm−2, an increase in polarization resistance to 10589 Ω·cm2, and a high corrosion inhibition efficiency of 96.88 %, suggesting that bzoxH2 significantly enhances the corrosion resistance of copper. Furthermore, studies based on adsorption isotherm models indicated that the adsorption behavior of bzoxH2 on the copper surface formed a dense passivation film through the combination of physical and chemical adsorption mechanisms. This effectively enhanced the corrosion resistance of copper and provided robust protection against corrosion. Finally, the use of X-ray photoelectron spectroscopy technology, along with an in-depth exploration of the geometric structure and chemical reactivity of the bzoxH2 molecule, revealed its complex interaction with specific active sites on the copper surface. These findings provided valuable theoretical insights, along with practical guidance for the development of metal corrosion inhibitors.

Effects of pyrazine and its derivatives as inhibitors on copper film chemical-mechanical polishing properties for ruthenium-based copper interconnect

During the one-step chemical mechanical polishing (CMP) process of ruthenium (Ru)-based copper (Cu) interconnected Cu films, a high Cu removal rate (RR) while maintaining a near zero Ru RR should be required to ensure a flat surface. The most ideal and difficult part of the CMP process is how to achieve rapid removal of Cu film without affecting Ru layer. Corrosion inhibitors in the slurry fulfill a significant function in controlling RR and improving the surface quality. Therefore, in this study, pyrazine (PY) and its derivative aminopyrazine (AP) as cost-effective and harmless corrosion inhibitors for Ru-based Cu interconnected Cu film CMP were investigated under weakly alkaline conditions (pH=8.5). First, through the utilization of experimental and theoretical methods, a systematical analysis was conducted to assess the corrosion inhibition effects of AP and PY, and it was found that the corrosion inhibition effect of AP was stronger than that of PY. Then, the adsorption and inhibition mechanism of AP on Cu/Ru surface were analyzed by electrochemical testing and X-ray photoelectron spectroscopy (XPS), and the adsorption behavior of AP molecules on the Cu (111) surface was investigated at the molecular level using quantum chemical methods. Finally, tests on Cu patterned wafers showed that the combination of 0.5 wt% AP and 0.5 wt% sarcosine (Sar) proved to be successful in effectively rectifying the step height on the Cu patterned wafer. At the same time, a high RR of 7281 Å /min, a low surface root mean square deviation (Sq) of 1.35 nm in 10 μm×10 μm region and a low static etching rate (SER) of 1015 Å /min were obtained with the synergistic effect of AP and Sar. This outcome holds substantial theoretical implications for advancing the formulation of low-node Cu film slurry.

Surface Interaction Effect and Mechanism of Methionine Derivatives as Novel Inhibitors for Alkaline Copper CMP: Insights from Molecular Simulation and Experimental Analysis

To prevent excessive corrosion caused by the slurry in the copper (Cu) chemical mechanical polishing (CMP) process, a corrosion inhibitor is normally required. In this study, the methionine (Met) derivative FMOC-L-Methionine (Fmoc-Met-OH) was explored as a corrosion inhibitor for Cu film CMP in weak alkaline conditions (pH = 8.5). A comprehensive evaluation was conducted to confirm the efficiency of Fmoc-Met-OH as a corrosion inhibitor, combining experiments and theoretical calculations. The results showed that Fmoc-Met-OH could effectively inhibit the corrosion of Cu, with a high inhibition efficiency (IE) of 78.26% while maintaining a high removal rate (RR) of 5703 Å min−1, a low static etch rate (SER) of 676 Å min−1, and a low surface root mean square deviation (Sq) of 1.41 nm. Simultaneously, the results of X-ray photoelectron spectroscopy (XPS) tests and electrochemical analysis confirm that Fmoc-Met-OH molecules can form a dense and ordered adsorption film on the Cu surface. According to the density functional theory (DFT) calculations and molecular dynamics (MD) simulation, it was verified that Fmoc-Met-OH exhibited strong chemical adsorption on Cu substrates, as evidenced by the high binding energy (E Binding) value, low energy gap (ΔE), and radial distribution function (RDF) analysis. The findings provided theoretical evidence of the better inhibition effectiveness of Fmoc-Met-OH at a molecular or atomic level.

Study on inhibition effect of 3-amino-1, 2, 4-triazole on chemical mechanical polishing of GLSI low-techology node molybdenum barrier layer

Considerable attention has been paid to utilizing molybdenum (Mo) as a new generation of barrier layer material in the integrated circuit industry. However, there have a small amount of papers for Mo chemical mechanical polishing (CMP). In this study, the inhibition effect of 3-amino-1, 2, 4-triazole (ATA) on corrosion and CMP of Mo in the weakly alkaline slurry was investigated. Electrochemical experiment and chemical mechanical polishing experiment demonstrated that 100 ppm ATA has an excellent inhibition performance of Mo (removal rate of Mo decreased from 509 Å/min to 322 Å/min, static etching rate of Mo decreased from 839 Å/min to 208 Å/min and Mo surface roughness decreased from 9.48 nm to 1.01 nm). Langmuir adsorption isotherm analysis found that physical and chemical adsorption exists simultaneously between ATA and Mo. X-ray photoelectron spectroscopy analysis showed that the addition of ATA changed the contents of different kinds of Mo oxides. With the decreasing of MoO3, more MoO2 was generated and protected Mo from corrosion. This paper is devoted to studying the inhibition effect of a traditional corrosion inhibitor on a new barrier layer material and analyzing its mechanism. Additionally, this paper is also helpful to prevent galvanic corrosion between Mo and other interconnection materials during CMP.

The Shear Force Law: A Guide to Modeling CMP Removal Rates

A new theory is presented that generalizes the classical version of Preston’s Law in chemical-mechanical planarization (CMP). The approach is motivated by removal rate data that cannot be explained by the classical version. The theory begins by observing that when removal rates are plotted against the measured wafer frictional shear force, the data often lie on or near half-lines that emanate from a common intercept on the removal rate axis. The half-lines have slopes that are indexed by polishing speed. While the common intercept might be interpreted as a static etch rate, evidence suggests that it may be due mainly to compliant pad fragments generated by conditioning. An extension of the new model outside of the experimental design using a Stribeck curve is found to explain the puzzling non-Prestonian removal rate trends. It also suggests an explanation for some frequently observed removal rate pressure thresholds. Finally, the new theory predicts that it is possible to scale the pressure and speed in CMP to obtain a desired scaling of the removal rate without changing the friction coefficient. The approach has been successfully applied to several recent metal and dielectric polishing processes that use a variety of consumables.

Effect of synergetic inhibition of nonionic surfactant and benzotriazone for molybdenum in chemical mechanical polishing

The continuous miniaturization of the feature size of integrated circuit makes it crucial to find proper barrier layer materials. With the properties of low resistivity (∼5.34 μΩ•cm) and good adhesion to Cu, Molybdenum (Mo) has become the most promising materials of the next generation of barrier layer. However, the studies on Mo chemical mechanical polishing (CMP) are limited. The problems of controlling Mo removal rate (RR) and improving its surface quality (Sq) are still unsolved. Here in, this paper focuses on minimizing Mo RR and Sq during CMP. Compared the inhibition effect of isooctanol polyoxyethylene ether (JFCE) and fatty alcohol polyoxyethylene ether (AEO-9) combine with benzotriazole (BTA) on Mo CMP, JFCE was selected as the most suitable surfactant. The addition of a small amount of JFCE can decrease Mo RR (from 308 Å/min to 176 Å/min) and static etching rate (SER) (from 201 Å/min to 50 Å/min) significantly. Furthermore, Mo Sq was also improved (from 6.34 nm to 0.255 nm) during CMP. The synergetic inhibition mechanism of JFCE and BTA was characterized by electrochemical test, contact angle test, adsorption isotherm, X-ray photoelectron spectroscopy, scanning electron microscopy and density functional theory. JFCE not only can change the proportion of Mo oxide, but also can complex with Mo chemically and physically, thus playing an inhibition effect on the convex and concave part of Mo surface. Furthermore, JFCE could keep the slurry stable at least for 7 days. This paper combined with experimental and theoretical methods to find a new Mo inhibitor, which has a promising effect to the study of barrier layer planarization of 14 nm sub-technology node.

Material Removal Characteristics of Abrasive-Free Cu Chemical-Mechanical Polishing (CMP) Using Electrolytic Ionization via Ni Electrodes

Recently, various efforts have been made to reduce the environmental burden caused by semiconductor manufacturing by improving the process efficiency. Chemical mechanical polishing (CMP), which is used to planarize thin films in semiconductor production, has also been studied to improve its efficiency by increasing the material removal rate (MRR) while reducing its environmental burden. Previous studies have been conducted to electrolytically ionize chemical solutions used in abrasive-free CMP for improving the MRR. In this study, we analyzed the change in the chemical solution according to the variation in voltage applied to the nickel (Ni) electrode in abrasive-free Cu CMP and studied the tribological material removal characteristics. The experimental results revealed that electrolytic ionization of the chemical solution for abrasive-free CMP increases the amount of dissolved oxygen (DO). The static etch rate of the Cu thin film and MRR in CMP increased as the voltage applied to the Ni electrode increased. The frictional force and temperature during CMP also increased as the applied voltage increased. Therefore, the increase in MRR caused by the increase in the applied voltage in abrasive-free Cu CMP using electrolytic ionization is plausibly caused by the chemical reaction between the dissolved oxygen in the chemical solution and Cu.

Experimental and density functional theory study of benzohydroxamic acid as a corrosion inhibitor in chemical mechanical polishing of Co interconnects

Benzohydroxamic acid (BHA) was evaluated for the first time as a corrosion inhibitor for cobalt (Co) films polishing for interconnect application. The inhibition mechanism of the BHA on the Co surface was comprehensively studied. Langmuir adsorption isotherm model analysis showed that BHA had both chemisorption and physical adsorption on Co. The active sites of BHA and BHA－ were analyzed by density functional theory (DFT). The calculation results show that the BHA molecule can be adsorbed vertically through the O1 atom, and parallel adsorbed through the benzene ring and the O1 atom. BHA－ ions are adsorbed through O1 and O2 atoms. Through polishing experiments, surface topography measurements, static etch rate (SER) experiments, and electrochemical impedance spectroscopy (EIS) experiments, it was found that the BHA inhibitor film was easily removed mechanically, and the inhibition mechanism was proposed. During the chemical mechanical polishing (CMP) process, the material in the raised area of the wafer is mechanically removed, and the material in the recessed area is protected by an inhibitor film, which not only ensures the removal rate (RR) of Co, but also ensures the surface quality of the wafer.

Synergistic effect of 1,2,4-triazole and phytic acid as inhibitors on copper film CMP for ruthenium - based copper interconnected and the surface action mechanism analysis

Ruthenium (Ru) has been selected as the next-generation barrier material for copper (Cu) interconnects due to its excellent electrical properties, high breakdown voltage, low leakage current, low resistivity and while improving the electromigration resistance of Cu interconnects. However, during the one-step chemical mechanical polishing (CMP) of Cu film, high removal rate of Cu and close to zero removal rate of Ru are required, which brings great difficulty to realize Cu film planarization. Inhibitors play a crucial role in controlling Cu and Ru removal rate and inhibiting the surface corrosion during the Cu films CMP. In this study, phytic acid as a green corrosion inhibitor was introduced in the Cu slurry and compared with 1,2,4-triazole (TAZ) as traditional inhibitor. From removal rate, static etch rate, surface quality and inhibition efficiency, it revealed that the corrosion inhibition of Cu and Ru by phytic acid was stronger than that of TAZ, while the obtained surface quality was weaker than that of TAZ. Through the analysis of UV–Visble spectroscopy and adsorption isotherm calculation, it revealed that the physical-chemical adsorption of both, which favored physical adsorption, existed on the Cu surface caused by weak van der Waals's forces. Therefore, in order to obtain dual physical-chemical adsorption and improve the passivation performance and inhibition efficiency, the mixture of both was adopted. The inhibition efficiency of Cu and Ru was increased to 53.7% and 66.4% compared with phytic acid alone, respectively. The static etch rate of Cu was dropped by 200 Å/min. The surface quality was significantly improved, and the roughness dropped to 1.64 nm. Through X-ray photoelectron spectroscopy analysis, it was showed that Cu-TAZ and Cu-phytic acid generated by the mixed inhibitor and Cu formed a double-layer physical-chemical adsorption film on the surface, which increased the coverage of adsorption sites and improved the inhibition efficiency. Finally, the stability test shows that the slurry can be stable for at least 7 days, which has theoretical guiding significance for the research and development of low-node Cu film slurry.

The study on corrosion inhibition effect of 3-amino-1, 2, 4-triazole and benzotriazole on molybdenum for barrier layer slurry

Molybdenum (Mo), as a barrier layer material, has great potential in integrated circuit (IC) manufacturing industries. The selection of suitable corrosion inhibitors to control the galvanic corrosion between Mo and the wiring metal is crucial in the Mo chemical mechanical polishing (CMP). In the current study, the inhibition effect of 3-amino-1, 2, 4-triazole (ATA), and benzotriazole (BTA) on Mo was investigated by experimental and theoretical methods. Static etching test found that the addition of ATA decreased the static etching rate of Mo (from 330 Å/min to 36 Å/min) more significantly than adding BTA (from 330 Å/min to 136 Å/min). Potentiodynamic polarization test indicated that ATA or low concentration (lower than 300 ppm) of BTA can improve the anti-corrosion ability of Mo. The smaller contact angle indicated that ATA (39°) was more hydrophilic than BTA (45°) in the formation of films covering the Mo surface. Scanning electron microscopy measurement observed that ATA-absorbed film was more compact and thinner, thus improving the surface morphology of Mo. The electronic properties and reactive sites of ATA were analyzed by quantum chemical calculation. Based on the simulation result, an adsorption model of ATA bonding with Mo basement was built. A large amount of ATA molecules coordinated with Mo atoms with its 4th N atom and formed a passivation film. The film is compact thus exhibits an excellent inhibition performance. Apart from this, the addition of ATA or BTA can improve the stability of solutions. The optimal dosage of ATA or BTA can keep the solution stable for 7 days. This paper combined with experimental techniques and theoretical calculations to further understand the mechanism of novel barrier layer material.

Effect and mechanism analysis of sarcosine on the chemical mechanical polishing performance of copper film for GLSI

With the decrease of integrated circuits feature size, chemical mechanical polishing (CMP) of copper (Cu) film for multilayer wiring is faced with new challenges. In order to reduce the step height of Cu film for cobalt-based Cu interconnect during CMP process, the selection of additives in the slurry is crucial. In this paper, sarcosine was used as an important additive in Cu slurry to improve the planarization properties. Through the polarization curves, dynamic polishing, static etching experiments and scanning electron microscopy (SEM) measurement, it was identified sarcosine as a complexing agent and trace functional reagent could improve the Cu planarization properties. Meanwhile, the adsorption and complexation mechanisms of sarcosine on Cu film surface were analyzed by electrochemical tests and X-ray photoelectron spectroscopy (XPS). The improvement of static etching and surface quality of Cu patterned wafers by sarcosine was verified by laser scanning confocal microscopy (LSCM). Low static etch rate (SER) (1658 Å/min), high removal rate (RR) (5091 Å/min), RR/SER of 3.07 and effective correction of the step height on Cu patterned wafers were achieved by the synergistic effect of sarcosine and benzotriazole (BTA). In this study, a green functional reagent for Cu film CMP in low-tech node multilayer wiring was provided, which is good practical application prospects.

Effects of H2O2 and pH on the Chemical Mechanical Planarization of Molybdenum

The effects of H2O2 on the chemical etching and removal rate (RR) of molybdenum (Mo) were investigated. Static etch rate (SER) and chemical mechanical planarization (CMP) experiments were performed using H2O2-based slurries at different pH levels. X-ray photoelectron spectroscopy (XPS) and potentiodynamic polarization analysis showed the formation of Mo oxides by the reaction between Mo and H2O2. The Mo SER, which increased with H2O2 concentration, supported the dissolution of Mo oxides through the formation of peroxo Mo complexes with H2O2. The CMP removal mechanism was demonstrated by comparing the CMP RR with and without silica abrasives. In addition, the Mo oxidation rate by H2O2 on a millisecond time scale was characterized with chronoamperometry to explain different RRs at pH values ranging from 2 to 8. The CMP RR of Mo was high at pH 2 and pH 10; however, pH 2 showed a lower SER than pH 10, leading to lower surface roughness.

Effect of Benzotriazole and 5-Methyl/1-H Carboxyl Benzotriazole on Chemical Mechanical Polishing of Cobalt in H2O2 Based Slurry

In this study, the passivation mechanism of three azole inhibitors with different functional groups, benzotriazole (BTA), 5-methyl-benzotriazole (TTA), 1-H carboxyl benzotriazole (CBT), on cobalt in H2O2 based slurry were investigated. Results showed that cobalt (Co) has the highest removal rate (RR) and static etching rate (SER) in the solution without inhibitors, and RR and SER of Co decreased when three inhibitors were added to the reference solution respectively. However, compared with BTA and TTA, CBT showed the strongest passivation effect. Through the single frequency EIS experiments and X-ray photoelectron spectroscopy (XPS) measurements analysis, all three azole inhibitors can react with Co2+ to form insoluble networked nanoparticles on the Co surface, but CBT had the thickest passivation film, which was inferred that the carboxyl group on the CBT can not only increase the coverage area on the Co surface like the methyl group, but also the oxygen on the carboxyl group can chemically adsorb on the Co surface like the N17 on the imidazole ring. Moreover, TTA showed better passivation effect than BTA due to the existence of the methyl on TTA, which can increase the coverage area on Co surface and prevent the polishing slurry from contacting Co surface.

Comparative Analysis of Chemical Mechanical Planarization Performance on Low-K Films

Mirroring the pursuit for ever-shrinking feature size in memory architectures, the need for materials capable of preventing crosstalk between increasingly closer conducting lines has led to the replacement of silicon dioxide with alternative low-k materials. Within this subset of materials exist films with notably low dielectric constants; however, these materials present unique challenges for chemical mechanical planarization (CMP) in comparison to more traditional dielectrics, the least of which include undesirable scratching and erosion (e.g. dishing) of low-lying areas. Fortunately, some degree of tuning of film properties (e.g. modulus and hardness) is possible through various deposition methods and post treatment conditions, among others. In this study, two slurries containing common Ceria abrasives were utilized to examine a selection of films of varying properties and preparations across several CMP process conditions. A structural test vehicle having a series of feature sizes designed to feed CMP modeling was used for analysis. Static etch rate and material removal rate were measured using optical metrology. Dishing was quantified via atomic force microscopy (AFM), and scratching performance was analyzed via optical methods. Using the collected data, a mechanism for removal was proposed for each slurry. Figure 1

Dishing-free chemical mechanical planarization for copper films

The importance of obtaining a dishing-free Cu-film chemical-mechanical planarization (CMP) has rapidly increased as the line width of Cu-wire integration in advanced semiconductor devices reduced to less than 10 nm. Unlike conventional etching (i.e., corrosion) dominant Cu-film CMP, which has been utilized for the last two decades, a novel chemical oxidation and etching dominant Cu-film CMP using a slurry performing Fenton reaction between a ferrous catalyst (Fe(CN)64−-) and oxidant (H2O2), a scavenger (arginine) effect, and the enhanced mechanical property of a nano-scale (i.e., 20 nm in diameter) crystalline ZrO2 abrasive could successfully obtain a dishing-free Cu-film CMP and good stability of abrasives in the slurry. In particular, the Cu-film polishing rate significantly increased with an increase in ferrous catalyst and scavenger concentrations; a 12-inch-wafer Cu-film polishing rate of >220 nm/min was obtained at a ferrous catalyst concentration of 2.0 wt% and a scavenger concentration of 1.0 wt%. Otherwise, the SiO2-film polishing rate significantly decreased with increasing ferrous catalyst and scavenger concentration. The dependencies of the chemical properties (i.e., static etch rate, surface chemical compositions, and corrosion) and mechanical properties (i.e., electrostatic force) proved that the CMP mechanism using Fenton reaction and the scavenger effect principally perform chemical oxidation (i.e., the formation of CuO and Cu2O on the Cu film surface) and etching dominant CMP simultaneously.

Effect of Dissolved Oxygen on Removal of Benzotriazole from Co during a Post-Co CMP Cleaning

A systematic study of the adsorption of benzotriazole on Co surface and its removal in aqueous solutions was carried out for post-CMP cleaning application. Static etch rate (SER) measurements and electrochemical impedance spectroscopy (EIS) were employed. The experimental results show that BTA adsorbed well on Co surface when it exposed to BTA solution at neutral and alkaline pH. BTA did not adsorb due to active Co dissolution at acidic pH. The effect of dissolved oxygen (DO) concentration in de-ionized (DI) water on the removal of Co-BTA complex layer was investigated. At DI water rinse process after BTA treatment, Co-BTA layer was maintained on Co surface when DO concentration of DI water was low. Interestingly, BTA was removed by DI water with high DO concentration.