• 한국전기전자재료학회논문지
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• 제18권4호
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• pp.303-308
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• 2005

In this paper, the effects of oxidants on tungsten chemical mechanical polishing (CMP) process were investigated using three different oxidizers such as Fe(NO₃)₃, KIO₃ and H₂O₂. Moreover, the interaction between the tungsten film and the oxidizer was discussed by potentiodynamic polarization measurement with three different oxidizers, in order to compare the effects of W-CMP and electrochemical characteristics on the tungsten film as a function of oxidizer. As an experimental result, the tungsten removal rate reached a maximum at 5 wt％ Fe(NO₃)₃concentration, and when 5 wt％ H₂O₂was added in the slurry, the removal rate of W increased. Also, the microstructures of surface layer by atomic force microscopy(AFM) image were greatly influenced by the slurry chemical composition of oxidizers. It was shown that the surface roughness and removal rate of the polished surface were improved in Fe(NO₃)₃than KIO₃. The electrochemical results indicate that the corrosion current density of the 5 wt％ H₂O₂ and 5 wt％ H₂O/sub 2+/＋ 5 wt％ Fe(NO₃)₃was higher than the other oxidizers. Therefore, we conclude that the W-CMP characteristics are strongly dependent on the kinds of oxidizers and the amounts of oxidizer additive.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.481-482
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• 2006

Chemical-mechanical polishing, the dominant technology for LSI planarization, is trending to play an important function in micro-electro mechanical systems (MEMS). However, MEMS CMP process has a couple of different characteristics in comparison to LSI device CMP since the feature size of MEMS is bigger than that of LSI devices. Preliminary CMP tests are performed to understand material removal rate (MRR) with blanket wafer under a couple of polishing pressure and velocity. Based on the blanket CMP data, this paper focuses on the consumable approach to enhance MEMS CMP by the adjustment of slurry and pad. As a mechanical tool, newly developed microstructured (MS) pad is applied to compare with conventional pad (IC 1400-k Nitta-Haas), which is fabricated by micro melding method of polyurethane. To understand the CMP characteristics in real time, in-situ friction force monitoring system was used. Finally, the topography change of poly-si MEMS structures is compared according to the pattern density, size and shape as polishing time goes on.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.66-66
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• 2007

Lead zirconate titanate (PZT) is one of the most attractive perovskite-type materials for ferroelectric random access memory (FRAM) due to its higher remanant polarization and the ability to withstand higher coercive fields. We first applied the damascene process using chemical mechanical polishing (CMP) to fabricate the PZT thin film capacitor to solve the problems of plasma etching including low etching profile and ion charging. The $0.8{\times}0.8\;{\mu}m$ square patterns of silicon dioxide on Pt/Ti/$SiO_2$/Si substrate were coated by sol-gel method with the precursor solution of PZT. Damascene process by CMP was performed to pattern the PZT thin film with the vertical sidewall and no plasma damage. The polarization-voltage (P-V) characteristics of PZT capacitors and the current-voltage characteristics (I-V) were examined by change of process parameters. To examine the CMP induced damage to PZT capacitor, the domain structure of the polished PZT thin film was also investigated by piezoresponse force microscopy (PFM).

• 소성∙가공
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• 제32권4호
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• pp.191-198
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• 2023

We examined the martensitic transformation kinetics for metastable stainless steel during electrochemical polishing (EP) using different types of electrolytes. Martensite fraction measured with EBSD showed that the electrolyte with high relative permittivity exhibited comparably higher levels of martensitic transformation. The amount of charge build-up on the specimen surface during EP with different types of electrolytes was calculated using COMSOL multiphysics simulations to understand these phase transformation characteristics. The effect of charge build-up-induced stress was analyzed using previously published first-principles calculations. We discovered that the electrolyte with high relative permittivity accumulated a greater amount of charge build-up, resulting in a stronger driving force for stress-induced martensitic transformation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.622-625
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• 2004

The CMP monitoring system was newly developed by the aid of friction force measurement, resulting from installation of piezoelectric quartz sensor on R&D polisher. The correlation between friction and CMP results was investigated in terms of tribological aspects by using the monitoring system. Various friction signals were monitored and analyzed by the change of experimental conditions such as pressure, velocity, pad and slurry. First of all, the lubrication regimes were classified with Sommerfeld Number through measuring coefficient of friction in ILD CMP. And then, the removal mechanism of abrasives could be understood through the correlation with removal rate and coefficient of friction. Especially, the amount of material removal per unit sliding distance is directly proportional to the friction force. The uniformity of CMP performances was also deteriorated as coefficient of friction increased.

• 한국기계연구소 소보
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• 통권18호
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• pp.67-74
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• 1988

The force sensor is essentially required in controlling robot manipulator in such applications as precise assembly of mechanical parts, deburring and polishing and various kinds of 6-axis force sensors are developed for these application. This paper presents the algorithm of horizontal assembly of circular cross-sectional workpiece using 3-axis force sensor and procedure to develop the sensor. The sensor is calibrated and tested using AID converter and 16 bit micro computer. The result is $\pm$0.03% FS of zero stability, 0.1%FS of linearity and $\pm$0.05% FS of resolution. The sensor will be used in the research of robot application such as assembly and deburring interfaced with micro computer based robot controller which is under development at the robotics lab.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.468-472
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• 2005

This paper is to investigate the influence of the endface quality on the loss characteristics of a plastic optical fiber connector for in-car network service. Using the parameters of the surface roughness and applied load, insertion loss of connector is measured. Due to scattering and change of refractive index, an optimal condition for low-loss coupling exists. We present the optimal condition as surface roughness $R_{rms}$ = 8 nm and contact load up to 50 N.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.711-714
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• 2004

Chemical mechanical polishing (CMP) has been widely accepted for the global planarization of multi-layer structures in semiconductor manufacturing. However, it still has various problems to the CMP equipment, in particular, among the CMP components, process variables are very important parameters in determining the removal rate and non-uniformity. Using a design of experiment (DOE) approach, this study was performed investigating the interaction between the various parameters such as turntable and head speed, down force and back pressure during CMP. Using statistical analysis techniques, a better understanding of the interaction behavior between the various parameters and the effect on removal rate, no-uniformity and ETC (edge to center) is achieved.

• 전자공학회논문지D
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• 제34D권12호
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• pp.76-82
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• 1997

Chemical mechanical polishing (CMP) has become widely accepted for the planarization of multi-interconnect structures in semiconductor manufacturing. However, perfect planarization is not so easily ahieved because it depends on the pattern sensitivity, the large number of controllable process parameters, and the absence of a reliable process model, etc. In this paper, we realized the planarization of deposited oxide layers followed by metal (W) polishing as a replacement for tungsten etch-back process for via formation. Atomic force microscope (AFM) is used for the evaluation of pattern topography during CMP. As a result, AFM evaluation is very attractive compared to conventional methods for the measurment of planarity. mOreover, it will contribute to analyze planarization characteristics and establish CMP model.

• 대한기계학회논문집A
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• 제29권9호
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• pp.1276-1281
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• 2005

Compound semiconductors are the semiconductors composed of more than two chemical elements. Lithium Tantalate$K_I$ wafer is used for several optical devices, especially surface acoustic wave(SAW) device. Because of the lithography in SAW device process, $LiTaO_3$ polishing is needed. In this paper, the commercial slurries $(NALC02371^{TM},\; ILD1300^{TM},\;ceria slurry)$ used for chemical mechanical polishing(CMP) were tested, and the most suitable slurry was selected by measuring material removal rate and average centerline roughness$(R_a)$. From these result, it was proven that $ILD1300^{TM}$ was the most suitable slurry for $LiTaO_3$ wafer CMP due to the chemical reaction between solution in slurry and material.