• 한국전기전자재료학회논문지
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• 제22권2호
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• pp.114-118
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• 2009

PVA (polyvinyl alcohol) brush cleaning method is a typical cleaning method for semiconductor cleaning process especially post-CMP cleaning. PVA brush contacts with the wafer surface and abrasive particle, generating the contact rotational torque of the brush, which is the removal mechanism. The brush rotational torque can overcome theoretically the adhesion force generated between the abrasive particle and wafer by zeta potential. However, after CMP (chemical mechanical polishing) process, many particles remained on the wafer because the brush was contaminated in previous post-CMP cleaning step. The abrasive particle on the brush redeposits to the wafer. The level of the brush contamination increased according to the cleaning run time. After cleaning the brush, the level of wafer contamination dramatically decreased. Therefore, the brush cleanliness effect on the cleaning performance and it is important for the brush to be maintained clearly.

• 한국정밀공학회지
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• 제21권11호
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• pp.46-52
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• 2004

CMP (Chemical-Mechanical Polishing) is a process in which both chemical and mechanical mechanisms act simultaneously to produce the planarized wafer. CMP process is an extensive usage and continuing high growth rates in the semiconductor industry. The understanding of the process, however, is much slower. The nature of material removal from the wafer is still undefined and ambiguous. Material removal rate according to the slurry flow rate is also undefined and ambiguous. Thus, in this study, the basic mechanism of material removal rate as slurry flow rate is defined in terms of energy supply and energy loss.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.93-96
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• 2003

Recently, various bulk metallic glasses (BMG's) haying good mechanical and chemical properties were developed. BMG's can easily be deformed in the supercooled liquid region, via viscous flow mechanism. In our previous work, we evaluated the deformation behavior and some other basic properties of Z $r_{41.2}$ $Ti_{13.8}$C $u_{12.5}$N $i_{10}$B $e_{22.5}$ alloy. In this study, we investigated the micro forming of Z $r_{41.2}$ $Ti_{13.8}$C $u_{12.5}$N $i_{10}$B $e_{22.5}$ alloy. The process condition was chosen based on the viscosity data from TMA, and superalloy and Si wafer with micro patterns on the surface were used as forming die. The alloy showed good replication of the patterns. However, some stripe patterns, resembling scratches, appeared on the deformed alloy surface. These scratches can be reduced or eliminated by polishing before forming.ing.ore forming.ing.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.972-975
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• 2002

An understanding of tribological behavior in CMP(Chemical Mechanical Polishing) is one of the most important things to reveal the mechanism of material removal. In CMP, the contact type is thought to be semi-direct, elastohydrodynamic contact type from the Stribeck diagram, which is a combination of solid-solid direct contact and hydrodynamic lubrication with thin liquid film. This study is focused on the decay of friction force during CMP from two points of view, one of which is change of the real contact area and the other is the decrease of the elastic modulus of the pad caused by the increase of the temperature during CMP Experiments are implemented with elastic modulus measuring system and tool dynamometer. Results show that the decay of friction force during CMP results from the decrease of the real contact pressure working on an abrasive, which is induced by the decrease of elastic modulus of pad caused by the increase of temperature. And, the phenomenon is thought to be happen specially in the case that the weight concentration of abrasive in slurry is small enough.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1117-1120
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• 2001

Chemical mechanical planarization(CMP) has emerged as the planarization technique of choice in both front-end and back-end integrated circuit manufacturing. Conventional CMP process utilize a polyurethane polishing pad and liquid chemical slurry containing abrasive particles. There have been serious problems in CMP in terms of repeatability and defects in patterned wafers. Since IBM's official announcement on Copper Dual Damascene(Cu2D) technology, the semiconductor world has been engaged in a Cu2D race. Today, even after~3years of extensive R&D work, the End-of-Line(EOL) yields are still too low to allow the transition of technology to manufacturing. One of the reasons behind this is the myriad of defects associated with Cu technology. Especially, dishing and erosion defects increase the resistance because they decrease the interconnection section area, and ultimately reduce the lifetime of the semiconductor. Methods to reduce dishing & erosion have recently been interface hardness of the pad, optimization of the pattern structure as dummy patterns. Dishing & erosion are initially generated an uneven pressure distribution in the materials. These defects are accelerated by free abrasive and chemical etching. Therefore, it is known that dishing & erosion can be reduced by minimizing the abrasive concentration. Minimizing the abrasive concentration by using Ce$O_2$ is the best solution for reducing dishing & erosion and for removal rate. This paper introduce dishing & erosion generating mechanism and a method for developing a semi-rigid abrasive pad to minimize dishing & erosion during CMP.

• Corrosion Science and Technology
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• 제4권5호
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• pp.211-216
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• 2005

Failure analysis of the latch ram ball and the C-ram ball with the trade name AFBMA Gr. 50 Colmonoy No. 6, has been performed to identify the root cause of the failure. The study required the extraction of the both failed and normal balls from the nuclear fuel exchanger. Microstructures of both balls were examined after polishing and etching. Breaking tests of both the ball revealed similarity in cleavage surfaces. Fracture surfaces of both failed ball and normal ball after breaking test were examined with SEM and EDX. Microstructure of the ball revealed an austenite phase with coarse Cr rich precipitate. Indented marks observed on the surface of the failed ball are believed to be produced by overloading. In the light of the afore mentioned observations and studies, the failure mechanism of the ball in nuclear fuel exchanger seem to be caused by impact or mechanical overloading on ball.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.171-175
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• 2001

Chemical mechanical polishing(CMP) process has been widely used to planarize dielectrics and metal, which can apply to employed in integrated circuits for sub-micron technology. Despite the increased use of CMP process, it is difficult to accomplish the global planarization of free-defects in inter level dielectrics and metal. Especially, defects like (micro-scratch) lead to severe circuit failure, and affects yield. Current conditioning method - bladder type, orbital pad motion- usually provides unsuitable pad profile during ex-situ conditioning near the end of pad life. Since much of the pad wear occurs by the mechanism of bladder type conditioning and its orbital motion without rotation, we need to implement new ex-situ conditioner which can prevent abnormal regional force on pad caused by bladder-type and also need to rotate the pad during conditioning. Another important study of ADPC is related to the orbital scratch of which source is assumed as diamond grit dropped from the strip during ex-situ conditioning. Scratch from diamond grit damaged wafer severely so usually scraped. Figure 1 shows the typical shape of scratch damaged from diamond. e suspected that intensive forces to the edge area of bladder type stripper accelerated the drop of Diamond grit during conditioning. so new designed Flat stripper was introduced.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.148-154
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• 1999

This study was carried out to verify grinding performance of dental diamond bur and investigate the possibility of AE application in dentistry field. Workpieces were made of acryl and bovine respectively for the experiments in this study. Grinding test was conducted to get the data of grinding resistance and specific grinding energy of four different types of diamond bur by using tool dynamometer. AE signal was acquired to verify grinding process in the AE measuring system. Tool wear was observed to find parameters about grinding characteristics of diamond bur by means of SEM picture. It was found that the wear of dental diamond bur could be detected with polishing of grinding material, removal of adhesive parts, wear of particles neighboring cutting nose, loss of material and elevation of temperature. The wear of B, C, D type diamond bur is due to wear and fracture of grain size. Abnormal state can be found through the behavior of AE signal in the grinding working. As a result, it is expected that forecast of abnormal state is possible using AE equipments under real time process.

• 대한치과보철학회지
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• 제39권1호
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• pp.37-48
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• 2001

Ceromers, new indirect resin system, are now being adopted for esthetic restorations. Despite of its translucency and good color matching, color stability after long-term use was unknown till now. This in vitro study was designed to evaluate color stability of some ceromers when subjected to brushing after thermocycling. Three types of ceromers: Scupture, Targis, Artglass and a direct resin system, Z100 were prepared to disks 12 mm in diameter, 2.5 mm in thickness. All specimens were polished, and Sculpture and Targis specimens were divided two groups, respectively. Then, half of them were glazed according to manufacturer's instructions. All specimen were brushed 20,000 times after 10,000 cycle thermocycling. Color was measured with spectrophotometer after 1,000, 3,000, 10,000 times thermocycling and 20,000 time brushing, respectively. Color difference (${\Delta}E$) was calculated according to CIE LAB system. During thermocycling, Sculpture & Targis system with polished surface showed greater color change than any other groups. After brushing, color difference was reduced significantly. Mean values of ${\Delta}E$ ranged 0.98 to 2.98. All Ceromers were considered clinically acceptable after thermocycling and brushing, and color change mechanism was affected by the brands and finishing methods. It might be concluded that color change of ceromer is due to surface alteration.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1450-1451
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• 2006

In this paper, we first applied the chemical mechanical polishing (CMP) process to the planarization of ferroelectric film in order to obtain a good planarity of electrode/ferroelectric film interface. $Bi_{3.25}La_{0.75}Ti_{3}O_{12}$ (BLT) ferroelectric fan was fabricated by the sol-gel method. Removal rate and non-uniformity (WIWNU%) were examined by change of silica slurries pH(10.3, 11.3, 12.3). Surface roughness of BLT thin films before and after CMP process was inquired into by atomic force microscopy (AFM). Effects of silica slurries pH(10.3, 11.3, 12.3) were investigated on the CMP performance of BLT film by the surface analysis of X-ray photoelectron spectroscopy(XPS).