• Design & Manufacturing
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• v.11 no.3
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• pp.51-55
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• 2017

Micro fuel cells have high reliability and long usage time. Among them, PEMFC (polymer Electrolyte Membrane Fuel Cell) is suitable as a portable power source because it is easy to fix electrolyte and simple structure. The bipolar plate, a key component of the fuel cell, is produced by cutting. In the case of micro fuel cell separator, burr is very small and the flow channel size in the separator is very small. Therefore, it is difficult to remove burrs in the usual way such as a brushing or ultra-sonic method. Therefore, this study proposed electrolytic polishing process and analyzed the characteristics of each condition by introducing the concept of roughness reduction rate. In addition, the ultrasonic process was added to analyze the effect of ultrasonic addition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.247-251
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• 2004

Chemical-Mechanical Polishing(CMP) especially is becoming one of the most important ULSI processes for the 0.25m generation and beyond. And there are many elements affecting CMP performance such as slurry, pad, process parameters and pad conditioning. Among these elements the CMP pad is considered one of the most important because of its change. But the surface of the pad has irregular pores, so there is non-uniformity of slurry flow and of contact area between wafer and the pad, and glazing occurs on the surface of the pad. So we make CMP pad with micro structure using micro molding method. This paper introduces the basic concept and fabrication technique of CMP pad with micro-structure and the characteristic of polishing. Experimental results demonstrate the removal rate, uniformity, and time vs. removal rate.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.8
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• pp.44-50
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• 2019

CMP is the most critical process in the manufacture of silicon wafers, and the use of retaining rings, which are consumable parts used in CMP equipment, is increasingly important. Since the retaining ring is made of plastic, it is not only weak in strength but also has the problem of taking a long time for the flattening operation of the ring itself performed before the CMP process, and of the imbalance of force due to bolt tightening causing uneven wear. In order to solve this problem, the retaining ring and the insert ring are integrally used, and the flatness of the retaining ring may be affected depending on the material of the insert ring. Also, the residual stress generated in the manufacturing process of the insert ring may cause distortion of the ring, which may adversely affect the precision polishing. In this study, when the insert ring is made of Zn or STS304, the thickness variation and the flatness of the retaining ring are compared and, finally, the material removal rate is analyzed by polishing the wafer by the oxide CMP process. Through these experiments, the effects of the insert ring material on the polishing accuracy of the wafers were investigated.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.61-67
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• 2004

In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. In this study, magnetic field-assisted polishing technique is applied to remove the burr which exists in nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals was investigated changing with polishing time and magnetic abrasive size. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.5 s.236
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• pp.726-733
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• 2005

A spherical surface referenced Shack-Hartmann method is studied for inspecting machining accuracy of large concave mirror This method is so strong to the vibration environment for using as an on-machine inspection system during polishing process of large optics comparing with the interferometry. The measuring uncertainty of the system is shown as less than p-v 150 m. On-machine measured surface profile data with this method is used for feed back control of the polishing time or depth to improve the surface profile accuracy of large concave mirror. Also, the spherical surface referenced Shack-Hartmann method is useful for measuring aspheric such as parabolic or hyperbolic surface profile, comparing that the interferomehy needs a special null lens, which is to be a reference and difficult to fabricate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.33-36
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• 2001

Chemical mechanical polishing(CMP) process has been widely used to planarize dielectric layers, which can be applied to the integrated circuits for deep sub-micron technology. The rise throughput and the stability in the device fabrication can be obtained by applying of CMP process to STI structure in 0.18$\mu\textrm{m}$ m semiconductor device. The reverse moat process has been added to employ in of each thin films in STI-CMP was not equal, hence the devices must to be effected, that is, the damage was occurred in the device area for the case of excessive CMP process and the nitride film was remained on the device area for the case of insufficient CMP process, and than, these defects affect the device characteristics. Also, we studied the High Selectivity Slurry(HSS) to perform global planarization without reverse moat step.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1296-1301
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• 2003

The chemical mechanical polishing(CMP) is necessarily applied to manufacturing the dielectric layer and metal line in the semiconductor device. The conditioning of polishing pad in CMP process additionally operates for maintaining the removal rate, within wafer non-uniformity, and wafer to wafer non-uniformity. But the fixed abrasive pad(FAP) using the hydrophilic polymer with abrasive that has the swelling characteristic by water owns the self-conditioning advantage as compared with the general CMP. FAP also takes advantage of planarity, resulting from decreasing pattern selectivity and defects such as dishing due to the reduction of abrasive concentration. This paper introduces the manufacturing technique of FAP. And the tungsten CMP using FAP achieved the good conclusion in point of the removal rate, non-uniformity, surface roughness, material selectivity, micro-scratch free contemporary with the pad life-time.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.329-333
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• 2003

In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. In this study, magnetic field assisted polishing technique is applied to remove the burr which exists in nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals was investigated changing with polishing time. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.

• Current Optics and Photonics
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• v.1 no.6
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• pp.618-625
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• 2017

In the present research, a new bending system using a segmented vacuum chuck for Stressed Mirror Polishing (SMP) is developed. SMP is a special fabrication method for thin aspheric mirrors, where simple flat or spherical fabrication is applied while a mirror blank is deflected. Since a mirror blank is usually glued to a bending fixture in the conventional SMP process, there are drawbacks such as long curing time, inconvenience of mirror replacement, risk of mirror breakage, and stress concentration near the glued area. To resolve the drawbacks, a new bending system is designed to effectively hold a mirror blank by vacuum. For the developed bending system, the optimal bending load to achieve the designated mirror deflection is found by finite element analysis and an optimization algorithm. With the measurement results of the deflected mirror surfaces with the optimal bending loads, the feasibility of the developed bending system is investigated. As a result, it is shown that the bending system is appropriate for the SMP process.

• International Journal of Control, Automation, and Systems
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• v.6 no.3
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• pp.386-393
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• 2008

A position control method for interpolating aspherical grinding and polishing tool path was reviewed and experimented in a nano precision machine. The position-base algorithm was reformed from the time-base algorithm, proposed in the previous study. The characteristics of the algorithm were in the velocity control loop with position feedback. The aspherical surface was divided by an interval at which each velocity and acceleration were calculated. The theoretical velocity was corrected by position error during processing. In the experiment, a machine was constructed and nano-scale linear encoders were installed at each axis. Relation between process parameters and the variation of position error was monitored and discussed. The best result from optimized parameters showed that the accuracy was 150nm and improved from the previous report.