Chemical Mechanical Polishing Cleaning Research Articles

(Invited) Novel Brush Design for Post CMP Cleans

Chemical Mechanical Polishing (CMP) process is one of the key processes in semiconductor wafer processing. A sub 10nm wafer fabrication process may require more than 40 dielectric and metal CMP steps. As CMP process requirements get more stringent, CMP slurries are formulated with smaller and smaller metal oxide abrasive particles. The abrasive particles may also be surface modified or doped with other metal oxides. Post CMP cleaning chemistry formulations are designed to remove polish byproducts, pad residues and abrasive particles from wafer surface. Chemical composition and PH are tuned for modulating wafer surface-particle interactions so brushes can mechanically “sweep” them off the surface. PVA brushes, used of post CMP cleans, are a highly porous network of crosslinked polyvinyl acetate with pore size in the range of 30 – 100 um and 80% - 90% porosity, depending on the type of brush being used. While PVA brushes have largely met the process capability requirements, they have limitations for advanced cleans such as nano-particle removal. As CMP process continues to expand to new dielectric and metal films for different process steps in wafer fabrication, there is a need for customized brush material and surface design for optimal cleaning efficiency.We discuss a new engineered post CMP brush design that shows high efficiency in nano-particle cleans and allows high level of material tunability. New brush design is an engineered composite with an open cell microporous core, overlaid with engineered fibers in form of loops. Brush design is compatible with existing post CMP cleans. Figure 1(a) shows the new design, where in DIW enters the brush through the center of microporous core and flows outwards to the surface. As water exits the surface, it flows over and across the loops and contacts the wafer surface. Flow resistance through core and loops can be independently tuned, which allows better fluid distribution and more effective cleans. Figure 1(b) show a close-up schematic of interaction between loop and particle. Flexing of the loops on brush surface provides improved contact as well as cleaning ability Brush design can be optimized for chemical and mechanical properties with choice of fiber material, fiber diameter and loop height. Figure 2 shows the Zeta potential of PVA and different loop materials. The fiber material maybe selected such that zeta potential of the loops can enhance mechanical action in removing particle. Mechanical action of the Loops can be modeled as a cantilever and force on the particle is exerted by flexing of the loops.Deflection of loops can be approximated with flexure stiffness of rods with point load at free end. For initial purposed loop is approximated as single element. The equation can be rewritten to calculate cleaning force P at the free end for given loop deflection (Y), P = 3EIY/L3 (1)Where E is elastic modulus, I = moment, L = length of fiber and for rod shapes; I = Pi*(r4/4)The adhesion of particles on the surface is due to the effect of van der Waals and electrostatic forces. The total adhesion force on the surface can be written as: F=F vdw + F edl (2) where Ft is total adhesion force, Fvdw is the van der Waals force, and Fedl is the electrostatic force.Fvdw = AR/6r2 (3)Where A is the Hamaker constant, R is particle radius, r is the separation distanceFor effective removal of particles, P >/= F (4)Flex force and adhesion force were modeled based on equation (1) and (3) and are shown in Figure 3. New brush design was used for post CMP cleaning of silicon dioxide wafers polished with ceria slurry. Two different brush designs were tested for cleaning efficiency. Modeling data and comparison with experimental results is presented. Figure 1

Contamination reduction for 150 mm SiC substrates by integrating CMP and Post-CMP cleaning

The quality of silicon carbide (SiC) substrates has great influence on the quality of the epitaxial layers atop. During the epitaxial growth, crystallographic defects and substrate contaminations may transform to various surface defects, such as carrots, polytype inclusions and scratches, which are detrimental to the performance and reliability of SiC devices. In general, chemical mechanical polishing (CMP) and post-CMP cleaning are the last two steps before the epitaxial growth, playing critical roles in controlling the scratch and contamination levels on the SiC substrates. In this article, the methods for reducing the aluminum (Al) and manganese (Mn) metal contaminations as well as other surface particle contaminations are investigated. We found that different commercial CMP slurries may lead to different contamination levels. Most importantly, by adding a scrubber cleaning step prior to the conventional RCA cleaning process, the contamination levels can be greatly reduced, achieving the quality for mass production.

Application of an optimized alkaline cleaning solution for inhibitor removal during the post-CMP process: Performance evaluation and mechanism analysis

With the continuous miniaturization of the feature size of semiconductor integrated circuits, the development of chemical mechanical polishing (CMP) technology for copper interconnection has been promoted, and at the same time, more stringent requirements and challenges have been put forward for post-CMP cleaning technology. Benzotriazole (BTA), which has been used as an inhibitor to decrease metal corrosion especially in copper CMP process, is the main object to be removed after the CMP process due to its highly hydrophobic nature. However, the current post-CMP cleaning method cannot achieve an effective balance between high removal efficiency of BTA and excellent surface quality after CMP cleaning. Therefore, a novel and efficient alkaline cleaning solution for post-CMP cleaning of copper is proposed, which is based on tetraethylammonium hydroxide (TEAOH), l-glutamate (Glu) and polyvinylpyrrolidone (PVP). The cleaning effect of copper surface was characterized by contact angle measurement, electrochemical system, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The ion exchange of TEAOH and Glu promotes desorption of BTA molecules from the copper surface. The presence of PVP plays a key role in improving the surface quality after cleaning. This cleaning solution was proved to be effective for BTA removal and achieving a nearly defect-free clean surface.

Composite complex agent based on organic amine alkali for BTA removal in post CMP cleaning of copper interconnection

The combination of FA/OII chelating agent and double complexing agent ammonium citrate can shift the ionization to the right (the dissolution of Cu-BTA), effectively break the Cu-N bond, and accelerate BTA removal on the copper surface. • Ammonium citrate's nucleophilic attack may occur near C2 and O4 atoms. • The electrophilic attack may occur near N22 and N26 atoms. • The pH value of the cleaning solution is stable at 10.24 for optimal removal of BTA. • Effect and mechanism of composite complex agent were studied by electrochemical, contact angle, SEM, FTIR and XPS. • Composite complex agent can complex copper ions, form copper amine complex and break the ionization balance of Cu-BTA. Benzotriazole (BTA) is a common corrosion inhibitor in chemical mechanical polishing (CMP). It is also the main pollutant to be removed in post CMP cleaning. In this paper, a new type of alkaline cleaning solution based on composite complexing agent was proposed for BTA removal. The optimal concentration and pH value of the cleaning solution were explored using electrochemical measurement and contact angle measurement. When the components were 200 ppm FA/OII chelating agent and 0.1 vol% ammonium citrate (pH = 10.24), BTA residue on copper surface can be effectively removed. Density Functional Theory (DFT) proved that ammonium citrate's nucleophilic attack may occur around C2 and O4 atoms, respectively. The electrophilic attack of ammonium citrate may occur around N22 and N26 atoms, respectively. The results of scanning electron microscopy (SEM) showed that a lower surface roughness was obtained after cleaning. Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements confirmed that the cleaning solution could complex copper ions, break the ionization balance of Cu-BTA and accelerate its dissolution, so as to remove BTA effectively.

Effect of Corrosion Inhibitor BTA on Silica Particles and their Adsorption on Copper Surface in Copper Interconnection CMP

In the process of chemical mechanical polishing (CMP) of multilayer copper wiring of integrated circuits, benzotriazole (BTA) as corrosion inhibitors and silica particles as abrasives are important components of polishing slurry. At the same time, they are also the main objects of post CMP cleaning. Under alkaline conditions (pH 10), the addition of BTA will affect the stability of silica particles, such as particle size and zeta potential, so as to affect the adsorption of particles on the copper surface. The effects of different concentrations of BTA on the adsorption of silica particles on copper surface were characterized by scanning electron microscopy (SEM), and the corresponding adsorption mechanism was also analyzed by X-ray photoelectron spectroscopy (XPS). The adsorption energies of BTA molecule and SiO2 molecule on copper surface were calculated by molecular dynamics simulation. The results show that 3 mM BTA reduces the adsorption capacity of SiO2 particles, and increasing the concentration of BTA will increase the adsorption capacity of SiO2 particles on the copper surface.

Effect of EDTA-based alkaline cleaning solution on TAZ removal in post CMP cleaning of copper interconnection

1,2,4-triazole (TAZ) has been proved to be an alternative to Benzotriazole (BTA) as an corrosion inhibitor in chemical mechanical polishing (CMP) of multilayer copper interconnection for integrated circuit. It has also become the main object to be removed in post CMP cleaning. In this paper, a new type of alkaline cleaning solution based on EDTA was proposed to remove TAZ on copper surface. The optimal concentration ratio and pH value of the alkaline cleaning solution were explored using electrochemical measurement, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) and scanning electron microscopy (SEM). When the components of the cleaning solution were 25mg/L ethylenediaminetetraacetic acid (EDTA) and 600mg/L dodecylbenzene sulfonic acid (LABSA) (pH = 10.6), the Cu-1,2,4-trazole compounds formed by TAZ contamination on the copper surface can be effectively removed. Density Functional Theory (DFT) was used to confirm that EDTA could break the bond of Cu-1,2,4-triazole through the strong interaction between O16、H2、H36 and copper surface. No corrosion was observed on the cleaned copper surface and surface roughness was lower, which indicated that the cleaning solution was suitable for the removal of TAZ on copper surface.

Experimental validation and molecular dynamics simulation of removal of PO residue on Co surface by alkaline cleaning solution with different functional groups

Potassium oleate (PO) is a promising inhibitor for cobalt wiring chemical mechanical polishing (CMP) of integrated circuit (IC) to replace benzotriazole (BTA). The insoluble Co-PO complex formed on cobalt surface in the process of CMP become the main organic residues object of post CMP cleaning. In this paper, tetramethylammonium hydroxide (TMAH) and three complexing agents with different functional groups were used to form alkaline cleaning solution to remove the organic residue of Co-PO complex on cobalt surface. The cleaning effect was characterized by contact angle, electrochemistry, atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). Furthermore, the cleaning mechanism was revealed by molecular dynamics simulation based on density functional theory (DFT). The results show that the carboxyl group in Ethylenediamine tetraacetic acid (EDTA) is more easily to chelate with Co(II), which could break the Co-PO complex to remove PO on the cobalt surface. The mechanism of removing corrosion inhibitors by complexing agents will be helpful to the post-CMP cleaning of new generation Cobalt wiring.

Synergistic effect of LABSA/JFCE combined surfactant system on the removal of particles on copper wafer surface

With the decrease of feature size of integrated circuits, higher requirements are put forward for the surface defects of copper interconnects after chemical mechanical polishing (CMP). Colloidal SiO2 is used as a common abrasive in the CMP slurry for copper interconnect, which is the main contaminant in the post-CMP cleaning process. The interaction parameters of the anionic surfactant Dodecylbenzenesulfonic acid (LABSA) and the nonionic surfactant fatty alcohol polyethylene ether (JFCE) were calculated. It was determined that when the ratio of LABSA/JFCE compound was 2:3 and the concentration was 1000 ppm, the synergistic effect of the two surfactants was the strongest. The effect of the composite surfactant on the particle removal was verified by scanning electron microscopy (SEM). When the compound ratio of LABSA and JFCE is 2:3, the maximum removal efficiency of particles on copper surface was 97.08%. The reactive sites of LABSA and JFCE were studied at B3LYP/6-31G (d,p) level. Their adsorption energies on copper surface were calculated. It was concluded that under the action of composite surfactant agent, the SiO2 particles physically adsorbed on the copper surface could be easily desorbed. The theoretical analysis is consistent with the experimental results; the compound cleaning solution is suitable for particle removal in post CMP cleaning.

Synergistic effect of composite complex agent on BTA removal in post CMP cleaning of copper interconnection

Benzotriazole (BTA) is a common corrosion inhibitor for chemical mechanical polishing (CMP) of multilayer copper wiring of integrated circuit. It is also the main object to be removed in post CMP cleaning. In this study, a new type of alkaline cleaning solution based on composite complex agent was proposed to remove BTA effectively. The optimal cleaning concentration ratio and pH value of the new complex complexing agent were explored through electrochemical measurement and contact angle measurement. When the components of cleaning solution were 250 ppm diethylenetriaminepentaacetic acid (DTPA), 1000 ppm FA/OII chelating agent and 100 ppm polyethyleneimine (PEI) (pH = 10.5), the contact angle of copper surface contaminated by BTA can be reduced from 58.1° contaminated by BTA to 25.1°. Density Functional Theory (DFT) proved that DTPA could reduce the adsorption energy of BTA on copper surface. The result of atomic force microscopy (AFM) and scanning electron microscopy (SEM) on copper surface showed that composite complexing agent does not cause corrosion and a lower surface roughness was obtained after cleaning. X-ray photoelectron spectroscopy (XPS) results verified that the cleaning solution could complex copper ions, break the Cu-N bond and promote the decomposition of the Cu-BTA adsorbed chemically on Cu2O, so as to remove BTA effectively.

The effect of citric acid based cleaning solution on particle adhesion and removal during post-Cu CMP cleaning

The cleaning of copper surface after chemical mechanical polishing (CMP) process is the necessary step since the surface could become contaminated by a large amount of defects. In this study, the adhesion forces between silica particles and copper surfaces have been investigated in citric acid based cleaning solution during post-Cu CMP cleaning process. Potassium hydroxide (KOH) and tetra methyl ammonium hydroxide (TMAH) were used to adjust the pH and Triton X-100 was used as a surfactant. The adhesion forces as well as the zeta potentials decreased with the addition of pH adjustors and surfactant as the concentration of citric acid was 0.5 wt%. By measuring the zeta potentials of silica particles and copper surfaces, the interaction forces between them were calculated based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory which verified the experimental results. It was also demonstrated that silica particles could be removed efficiently by the proposed solution under cleaning process experiments.

Optimization of cleaning process parameters to remove abrasive particles in post-Cu CMP cleaning * * Project supported by the Major National Science and Technology Special Projects (No. 2016ZX02301003-004-007), the Natural Science Foundation of China (No. 61704046), the Scientific Innovation Grant for Excellent Young Scientists of Hebei University of Technology (No. 2015007), and the Hebei Natural Science Foundation Project (No. F2018202174).

The cleaning of copper interconnect chemical mechanical polishing (CMP) is a key process in integrated circuits (ICs) fabrication. Colloidal silica, which is used as the abrasive material in copper CMP slurry, is considered as the main particle contamination. Abrasive particle residuals can cause device failure which need to be removed efficiently. In this paper, a type of CMP cleaner was used for particle removal using a cleaning solution consisting of FA/O II chelating agent and FA/O I surfactant. By varying the parameters of brush rotation speed, brush gap, and de-ionized water (DIW) flow rate, a series of experiments were performed to determine the best cleaning results. Atomic force microscope (AFM) measurement was used to characterise the surface morphology of the copper surface and the removal of abrasive particles. A scanning electron microscope (SEM) with EDX was used to observe and analyze the particles shape and elements. The optima parameters of CMP cleaner were obtained. Under those conditions, the abrasive silica particles were removed effectively.

Effect of Brush Treatment and Brush Contact Sequence on Cross Contaminated Defects during CMP in-situ Cleaning

Chemical mechanical polishing (CMP) is one of the most important processes for enabling sub-14 nm semiconductor manufacturing. Moreover, post-CMP defect control is a key process parameter for the purpose of yield enhancement and device reliability. Due to the complexity of device with sub-14 nm node structure, CMP-induced defects need to be fixed in the CMP in-situ cleaning module instead of during post ex-situ wet cleaning. Therefore, post-CMP in-situ cleaning optimization and cleaning efficiency improvement play a pivotal role in post-CMP defect control. CMP in-situ cleaning module normally consists of megasonic and brush scrubber processes. And there has been an increasing effort for the optimization of cleaning chemistry and brush scrubber cleaning in the CMP cleaning module. Although there have been many studies conducted on improving particle removal efficiency by brush cleaning, these studies do not consider the effects of brush contamination. Depending on the process condition and brush condition, brush cross contamination effects significantly influence post-CMP cleaning defects. This study investigates brush cross contamination effects in the CMP in-situ cleaning module by conducting experiments using 300mm tetraethyl orthosilicate (TEOS) blanket wafers. This study also explores brush pre-treatment in the CMP tool and proposes recipe effects, and critical process parameters for optimized CMP in-situ cleaning process through experimental results.

Effect of chelating agent on benzotriazole removal during post copper chemical mechanical polishing cleaning

During the chemical mechanical polishing (CMP) process of copper, benzotriazole (BTA) is the most commonly used inhibitor, especially in acidic slurry. The post CMP cleaning process is mainly removal of slurry particles and organic residues. The presence of BTA results in a hydrophobic surface of copper, which leads to difficulty in cleaning, and BTA is the main organic residue. The BTA on the copper surface should be removed by using an effective cleaning solution. In this paper, a novel alkaline chelating agent with functionalities of BTA removal was designed for advanced post CMP cleaning solution. The alkaline chelating agent was used as main composition of cleaning agent. When the chelating agent concentration is 100–150ppm, it can effectively remove Cu–BTA. The removal of BTA is characterized by contact angle measurement, electrochemical methods and static etching rate (SER) measurement. The corrosion protection ability of the cleaning solutions was quantified by potentiodynamic polarization studies. Atomic force microscopy (AFM) measurement was used to monitor the surface quality of copper after cleaning.

Study of Pyrazole as Copper Corrosion Inhibitor in Alkaline Post Chemical Mechanical Polishing Cleaning Solution

In microelectronics fabrication, post chemical mechanical polishing (CMP) cleaning is required to remove organic contaminants and particles left on copper interconnects after the CMP process. Use of cleaning solutions, however, causes serious reliability issues due to corrosion and recession of the interconnects. In this study, Pyrazole is demonstrated to be a potentially superior Cu corrosion inhibitor for tetramethyl ammonium hydroxide (TMAH)-based post CMP cleaning solutions at pH 14. Micropattern corrosion screening results and electrochemical impedance spectroscopy (EIS) revealed that 1 mM Pyrazole in 8 wt% TMAH solution inhibits Cu corrosion more effectively than 10 mM benzotriazole (BTA) under same conditions. Moreover, water contact angle measurement results also showed that Pyrazole-treated Cu surfaces are relatively hydrophilic compared to those treated with BTA/TMAH. X-ray photoelectron spectroscopy (XPS) analysis supports Cu-Pyrazole complex formation on the Cu surface. Overall Cu corrosion rate in TMAH-based highly alkaline post CMP cleaning solution is shown to be considerably reduced to less than 1Å/min by addition of 1 mM Pyrazole.

Tribochemical interaction between nanoparticles and surfaces of selective layer during chemical mechanical polishing

Nanoparticles have been widely used in polish slurries such as those in the chemical mechanical polishing (CMP) process. For understanding the mechanisms of CMP, an atomic force microscope (AFM) is used to characterize polished surfaces of selective layers, after a set of polishing experiments. To optimize the CMP polishing process, one needs to get information on the interaction between the nano-abrasive slurry nanoparticles and the surface of selective layer being polished. The slurry used in CMP process of the solid surfaces is slurry with large nanoparticle size colloidal silica sol nano-abrasives. Silica sol nano-abrasives with large nanoparticle are prepared and characterized by transmission electron microscopy, particles colloidal size, and Zeta potential in this paper. The movement of nanoparticles in liquid and the interaction between nanoparticles and solid surfaces coating with selective layer are very important to obtain an atomic alloy smooth surface in the CMP process. We investigate the nanoparticle adhesion and removal processes during CMP and post-CMP cleaning. The mechanical interaction between nanoparticles and the wafer surface was studied using a microcontact wear model. This model considers the nanoparticle effects between the polishing interfaces during load balancing. Experimental results on polishing and cleaning are compared with numerical analysis. This paper suggests that during post-CMP cleaning, a combined effort in chemical and mechanical interaction (tribochemical interactions) would be effective in removal of small nanoparticles during cleaning. For large nanoparticles, more mechanical forces would be more effective. CMP results show that the removal rate has been improved to 367 nm/min and root mean square (RMS) of roughness has been reduced from 4.4 to 0.80 nm. Also, the results show that the silica sol nano-abrasives about 100 nm are of higher stability (Zeta potential is −65 mV) and narrow distribution of nanoparticle size. Consequently, one kind of alkali slurry containing 100-nm silica sol for the solid surfaces CMP coating through selective transfer is studied in this paper.

Frictional Analysis of PVA Brush for Post CMP Cleaning: Effects of Rotation Speed, Compression Distance, and Fluid Viscosity

Chemical mechanical polishing (CMP) is widely used in the surface planarization process of semiconductor fabrication. The planarization process produces a large amount of surface residue that must be removed before the next process is initiated. Typically, a combination of roll-and pen-type polyvinyl acetal (PVA) brushes is used for removing such contaminants. In the subsequent 450-mm wafer processing step, PVA brush cleaning is a viable candidate for post-CMP cleaning. However, given that the mechanisms of nanoscale particle cleaning are still under investigation [1-, the designs and operating conditions for brush cleaning are determined by trial and error. In this study, as a first step toward understanding the cleaning mechanisms, the tribological contact condition of the PVA roll brush (i.e., hydrodynamic, mixed, or boundary lubrication) is considered by measuring the frictional coefficients. In particular, the effects of rotation speed, compression distance, brush length, and fluid viscosity on the friction force are investigated.

Electrochemical Impedance Spectroscopy (EIS) Analysis of BTA Removal by TMAH during Post Cu CMP Cleaning Process

An ex situ electrochemical impedance spectroscopy (EIS) method is used to evaluate the effectiveness of tetramethyl ammonium hydroxide (TMAH) in removing benzotriazole (BTA) layer from Cu surface after chemical mechanical polishing (CMP). Since the in situ EIS measurements could not be applied to characterize the cleaning process, ex situ EIS measurement is used in the present work. The impedance data are modeled by electrical equivalent circuit (EEC) analysis and the polarization resistance values are calculated. The BTA removal for various concentrations of TMAH is quantified from polarization resistance values. Scanning electron microscopy and X-ray photoelectron spectroscopy measurements were also conducted to complement the studies. The results show TMAH is effective in removing the BTA layer and that when part of the BTA is removed, the residual BTA appears as nodules. Some of the native oxides and hydroxides on the Cu surface are also removed by TMAH. When the slurry contains 0.1% (wt) BTA, a minimum concentration of 0.5% (wt) TMAH and a minimum cleaning time of 60 s are required for complete removal of BTA from the Cu surface. The suggested ex situ EIS technique is sensitive in evaluating removal efficiency of the organic contaminant from the metallic surface.

The Effect of PVA Brush Scrubbing on Post CMP Cleaning Process for Damascene Cu Interconnection

Cu (copper) has been widely used for interconnection structure in integrated circuits because of its properties such as a low resistivity and high resistance to electromigration when compared with aluminum [1, 2]. Damascene process for the interconnection structure utilizes 2-steps CMP (chemical mechanical polishing). After 2-steps CMP process, many abrasive particles leave on the wafer surface, which should be removed in post-Cu CMP cleaning process. Cleaning efficiency affects directly on the subsequent process and device yield [3]. Therefore, cleaning of abrasive particles is the critical issue in semiconductor manufacturing.

계면활성제가 첨가된 DHF의 Post-Oxide CMP 세정 공정에의 적용 연구

Post-Oxide CMP(Chemical-Mechanical Polishing) 결과 실리콘 웨이퍼를 오염 시키고 있는 슬러리 입자의 세정 가능성을 조사하기 위하여DHF(Diluted HF)에 비이온성 계면 활성제인 PAAE(Polyoxyethylene Alkyl Aryl Ether), 비양성자성 용제인 DMSO(Dimethylsulfoxide) 와 초순수의 혼합물인 새로운 세정액을 제조하였다. 세정력을 평가하기 위해서 세정제 내에서 각각 다른 제타 포텐셜을 갖는 실리카(<TEX>$SiO_2$</TEX>), 알루미나(<TEX>$Al_2O_3$</TEX>)와 PSL(polystylene latex) 입자를 실리콘 웨이퍼 표면의 산화막에 인위적으로 오염시킨 후 실험에 이용하였다. 초음파하에서 세정액의 성능 평가 결과 본 세정기술은 효과적인 입자의 세정능력과 금속이온에 대한 세정 능력을 나타내고 있음을 확인하였다. 즉 기존의 APM(<TEX>$NH_4OH,\;H_2O_2$</TEX>와 D.I.W의 혼합물)과 달리 상온에서 세정이 가능하고 세정과정이 단축 되었으며, 낮은 농도의 HF를 사용함으로써 최소의 에칭에 의하여 표면 거칠기를 감소시킬 수 있음을 보여주고 있다. 또한 주요 CMP 금속 배선 물질들에 대한 낮은 부식력으로 기존의 CMP 후 세정공정에 뿐만 아니라 차세대CMP 공정으로 각광 받고 있는 Copper CMP 에 대한 Brush 세정 공정의 보조 세정제로 본 세정제가 적용될 가능성이 있음을 확인하였다. In order to remove particles on surface of post-oxide CMP wafer, new cleaning solution was prepared by mixing with DHF (Diluted HF), nonionic surfactant PAAE (Polyoxyethylene Alkyl Aryl Ether), DMSO (Dimethylsulfoxide) and D.I.W.. Silicone wafers were intentionally contaminated by silica, alumina and PSL (polystylene latex) which had different zeta potentials in cleaning solution. This cleaning solution under megasonic irradiation could remove particles and metals simultaneously at room temperature in contrast to traditional AMP (mixture of <TEX>$NH_4OH,\;H_2O_2$</TEX> and D.I.W) without any side effects such as increasing of microroughness, metal line corrosion and deposition of organic contaminants. This suggests that this cleaning solution would be useful future application with copper CMP in brush cleaning process as well as traditional post CMP cleaning process.

Novel post CMP cleaning using buffered HF solution and ozone water

Post chemical mechanical polishing (CMP) cleaning is a key process for copper (Cu) CMP in dual damascene interconnection technology. During the post CMP cleaning, it is an important issue to minimize organic and Cu contamination residues on the dielectric surface. This study proposed a novel post CMP cleaning using HAL buffer hydrofluoric (BHF) solution and ozone (O 3) water cleaning. The performance of the proposed cleaning technology was investigated and compared to conventional citric solution cleaning, which is currently used in post Cu CMP cleaning. From roughness, contamination residues and electrical characteristics, the proposed cleaning technology showed better performance than citric solution cleaning did. This excellent cleaning performance is attributed to the surface etching and contamination elimination effect of HAL BHF solution and O 3 water. Based on the experimental results, the proposed cleaning technology is feasible and superior to the conventional post CMP cleaning.