• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.86-93
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• 2008

This paper presents a design of the reticle stage for lithography using VCM(Voice Coil Motor) and kinematic analysis. The stage has three axes for X,Y,${\theta}_z$, those actuated by three VCM's individually. The reticle stage has cross coupled relations between X,Y,${\theta}_z$ axes, and the closed solution of the forward/inverse kinematics were solved to get an accurate reference position. The reticle stage for lithography was designed for reaching both high accuracy and long stroke, which was $0.1{\mu}m$ (X,Y)/ $1{\mu}rad({\theta}_z)$ accuracies and relatively long strokes about 2mm (X,Y) and 2 degrees(${\theta}_z$). Also this research presents a rotational compensation algorithm for the precision gap sensor for the stage. Simulation results show the overall performance of the whole algorithm and the improvement quantity of the rotational compensation algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.539-542
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• 1997

We present a micro-positioning stage that has minimized geometrical error and can drive in the 4-axis. This stage divided into two parts: $Z\theta_x$ $\theta_y$, motion stage and$\theta_z$ motion stage. These stages are constructed in flexure hinges, piezoelectric actuators and displacement scnsors. The dynamic model for each stage is obtained and their FE (finite element) models are made. Using the Lagrange's equation, the motion of equation is found. Through the parametric analysis and FE analysis, sensitiv~ty of the design parameters is executed. Finally, fundamental frequencies, maximum stress, and displacement sensitivity for each stage are obtained. We expect that this micro-positioning stage be a useful micro-alignment device for various applications.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.186-194
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• 2004

Micro-stereolithography is a newly proposed technology as a means that can fabricate a 3D micro-structure of free form. It makes a 3D micro-structure by dividing the shape into many slices of relevant thickness along horizontal surfaces, hardening each layer of slice with a focused laser beam, and stacking them up to a desired shape. In this technology, differently from the conventional stereolithography, scale effect is dominant. To realize micro-stereolithography technology, we developed the micro-stereolithography apparatus which is composed of an Ar+ laser, x-y-z stages. controllers. optical devices and scan path generation software. Related processes were developed, too. Using the system, a number of micro-structures were successfully fabricated. Some of these samples are shown for prove this system. Laser scan path generation algorithm and software considering photopolymer solidification phenomena as well as given 3D model were developed. Sample fabrication of developed software shows relatively high dimensional accuracy compared to the uncompensated result.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1080-1083
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• 1997

Micro-stereolithography is a newly proposed technology as a means that can fabricate 3D micro-structures of free form. It makes a 3D structure by dividing the shape into many slices of relevant thickness along honzontal surfaces, hardening each layer of slice with a laser, and stacking them up to a des~red shape. Scale effect becomes important in this micro-fabrication process, d~fferently from the conventional stereolithography. To realize this micro-stereolithography technology, we developed an equipment using Ar+ laser, xyz stages, controllers and all the optic devices. Using the equipment, a number of micro-structures were successfully fabricated including a winecup of several tens of micrometers.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.7
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• pp.579-586
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• 2016

This paper describes kinematic analysis of a 6-degrees-of-freedom (DOF) ultra-precision positioning stage based on a flexure hinge. The stage is designed for processes which require ultra-precision and high load capacities, e.g. wafer-level precision bonding/assembly. During the initial design process, inverse and forward kinematic analyses were performed to actuate the precision positioning stage and to calculate workspace. A two-step procedure was used for inverse kinematic analysis. The first step involved calculating the amount of actuation of the horizontal actuation units. The second step involved calculating the amount of actuation of the vertical actuation unit, given the the results of the first step, by including a lever hinge mechanism adopted for motion amplification. Forward kinematic analysis was performed by defining six distance relationships between hinge positions for in-plane and out-of-plane motion. Finally, the result of a circular path actuation test with respect to the x-y, y-z, and x-z planes is presented.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.51-58
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• 2008

This paper presents a new design of the precision stage for the reticle in lithography process and a low hunting control method for the stage. The stage has three axes for X, Y, ${\theta}_z$ those actuated by three voice coil motors individually. The designed reticle stage system has three gap sensors and voice coil motors, and supported by four air bearings and the forward/inverse kinematics of the stage were solved to get an accurate reference position. When a stage is in regulating control mode, there always exist small fluctuations(stage hunting) in the stage movement. Because the low stage hunting characteristic is very important in recent lithography and nano-level applications, a special regulating controller for ultra low hunting is proposed in this paper. Also this research proposed the 2-step transmission system for preventing the noise infection from environmental devices. The experimental results showed the proposed regulating control system reduced hunting noise as 35nm(rms) when a conventional PID generates 77nm(rms) in the same mechanical system. Besides the reticle stage has 100nm linear accuracy and $1{\mu}rad$ rotation accuracy at the control frequency of 8kHz.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.244-247
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• 2002

The performance of the precision micro-positioning 4-dof stage is presented. The compact design utilizes the monolithic mechanism to achieve the translation in the Z axis and rotation in the $\theta$ z, $\theta$ x and $\theta$ y axes with high stiffness and high damping. Hysteresis, nonlinearity, and drift of the piezoelectric effects are improved by incorporating the sensors in a feedback control. Experiments demonstrate that the micro-positioning stage is capable of 2nm resolution over the travel range of 25$\mu\textrm$ m in the Z axis, 0.0l7 $\mu\textrm$ rad resolution over the 170$\mu\textrm$ rad in the $\theta$ z and 0.011 $\mu\textrm$ rad resolution over the $\mu\textrm$ rad in the $\theta$ x and $\theta$ y axes. The cross-axis interferences among the axes are at a noise range. This stage is available for positioning error compensation of the XY stage with large stroke.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.468-472
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• 2005

In this paper, the static and dynamic stiffness of the air bearing stage for micro-micro machine tool are examined experimentally. For stiffness and precision concerns, air bearing stages are adapted for 3-axis micro-milling machine which is size of $200x200\;mm^2$. The air bearings in the stage are preloaded by permanent magnets to achieve desired bearing clearance and stiffness for vertical direction. As the stiffness of the air bearing is primary interests, static stiffness test were performed on XY stage in Z direction and Z column in Y direction. Dynamic test were performed on XY stage and Z column, respectively. Both static and dynamic tests were performed in different air pressure conditions. The vertical stiffness of XY stage is about 9 N/ pm where Y stiffness of Z column is much smaller as $1\;N/{\mu}m$ because of the large moment generated by Y force on the column.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.387-390
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• 1999

누설탄성표면파(Leaky Surface Acoustic Wave : LSAW) 측정에 사용하는 것을 목적으로 PVBF 압전막을 이용하여 직선집속 초음파트랜스듀서를 제작하고 그 특성을 평가하였다. 제작은 한쪽 면이 원통형 구조를 갖는 구리, 알루미늄, 3mmPVC-에폭시 3가지 재료를 배면층으로 사용하여 각각에 PVDF를 부착시켜서 수중에 음파를 방사하도록 구성하였고, 특성평가는 임펄스응답 특성과 음장 특성으로 나누어서 평가하였다. 임펄스응답 특성은 제작한 3종류의 집속 초음파트랜스듀서에 대해 실험적으로 측정하고, Mason 등가회로1)를 이용한 이론적 해석결과와 비교하였다. 음장특성 측정실험은 구리를 배면체로 하여 제작한 집속 초음파트랜스듀서에 대해서 실시하였고, 그 이론적인 계산결과는 Raylelgh-Somme-rfeld 회 절이론2)을 도입하여 초점면에 형성되는 음압분포를 계산하는 것으로 얻어졌다. 실험은 펄스 초음파 송수기 및 $2{\mu}m/step$으로 이동하는 정밀 x-y-z 스테이지를 컴퓨터에 연결하여 자동 측정하는 것으로 수행되었는데, 그 결과는 이론 해석결과와 비교적 잘 일치하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1871-1874
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• 2005

The direct write FIB technology has several advantages over contemporary micro-machining technology, including better feature resolution with low lateral scattering and capability of maskless fabrication. Therefore, the application of FIB technology in micro fabrication has become increasingly popular. In recent model of FIB, however the feeding system has been a very coarse resolution of about a few ${\mu}m$. Our research is the development of nano stage of 200mm strokes and 10nm resolutions. Also, this stage should be effectively operating in ultra high vacuum of about $1x10^{-7}$ torr. This paper presents the discussion and results of CAE of the 2 axes stages. we have estimated the stable static and dynamic characteristics for dual servo system. Therefore the 2 axes stages developed and future work are introduced at the end of the paper.