• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1404-1408
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• 2006

In this paper, a hybrid-type vibration isolator which has air chamber(spring) and viscous damper in series is developed. The developed vibration isolator is designed to perform 3 following functions : spring function for normal operating conditions, damping function to reduce an impact for sudden move of upper beam, and finally leveling function. Based on the given natural frequency and damping factor, the design procedure is proposed. The performance of the developed isolator is tested by measuring stiffness and damping.

• 반도체디스플레이기술학회지
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• 제6권1호
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• pp.37-41
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• 2007

Recently PZT is used in ultra precision mechanism field. PZT has a small motion range although it has a high resolution. Many methods, such as inchworm, impact driving, etc., have been applied for the expansion of the motion range.? In this study, the new actuating mechanism for rotational motion with two PZT actuators is proposed. The ultra precision rotational actuator which is made by proposed mechanism is able to operate both coarse and fine motion. The design parameters of the proposed mechanism are considered to improve the performance of the system. The rotational stage which is applied by the proposed mechanism is fabricated. The resolution and velocity for fabricated rotational stage are measured by laser interferometer.

• 한국기계가공학회지
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• 제13권6호
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• pp.15-22
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• 2014

With a conventional positioning apparatus, it is very difficult simultaneously to achieve desired driving ranges and precision levels at the sub-micrometer level. Generally, a lead screw and friction drive have been used as servo control systems. These have large driving ranges, and high-speed positioning is feasible. In this study, we present a global servo system controlled by a laser interferometer acting as a displacement measurement sensor for achieving positioning accuracy at the sub-micrometer level.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.54-59
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• 2005

Recently, the ultra-precision stage is widely used in the fields of the nano-technology, specially in AFMs(Atomic Force Microscope) and STMs(Scanning Tunneling Microscope). In this paper, the ultra-precision stage which consists of flexure hinges, piezoelectric actuator, and ultra-precision linear encoder, is designed and developed. The guide mechanism which consisted of flexure hinges is analyzed by Finite Element Method. And we derived the transfer function of the system in 1st order system from step responses according to the magnitude. We performed simulation for the model to tune the control gain and applied the gains to the developed system. Experimental results found that the stage can be controlled in 5 nm resolution by PID controller.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1883-1886
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• 2005

In this paper, a decoupled dual servo (DDS) stage for ultra-precision scanning system with large working range is introduced. In general, dual servo systems consist of a fine stage for short range and a coarse stage for long range. The proposed DDS also consists of a $XY\theta$ fine stage for handling and carrying workpieces and one axis coarse stage. Its coarse stage consists of air bearing guide system and a coreless linear motor with force ripple. The fine has four voice coil motors(VCM) as its actuator. According to a VCM's nature, there are no mechanical connections between coils and magnetic circuits. Moreover, VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about $25mm^2$. To break that hurdle, the coarse stage with linear motors is used to move the fine about 500mm. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. With MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. And for their movements without any frictions, guide systems of the DDS are composed of air bearings. To get precisely their positions, a linear scale with 5nm resolution are used for the coarse stage's motion and three plane mirror laser interferometers with 5nm for the fine's $XY\theta$ motions. With them, on scanning the two stages have same trajectories. The control algorithm is named Parallel method. The embodied ultra-precision scanning system has sub 100nm following error and in-positioning stability.

• 한국광학회지
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• 제4권1호
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• pp.15-21
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• 1993

본 연구에서는 설계제작된 KrF 엑시머 레이저 스텝퍼는 광원인 KrF엑시머 레이저, 조명광학계, 축소트영광학계, 정밀구동 웨이퍼 스테이지, 정렬시스템 및 이들을 제어하기 위한 제어계로 구성되어 있다. 본 실험에서 사용한 KrFdprtlaj 레이저는 밴드폭 3pm, 반복주파수 200Hz, 평균축력 3W이고, 5:1 투영렌즈는 N.A. 0.42, 전체 필드영역 $\varphi$21.2mm, 왜곡수차 최대 60nm 이하이다. 또한 정밀구동 웨이퍼 스테이지의 재현성과 해상도는 각각 $\pm$0.08$\mu\textrm{m}$/200mm(3 sigma), 100mm 반경에서 0.05 $\mu\textrm{m}$이다. 자동 초점 시스템은 $\pm$50$\mu\textrm{m}$범위에서 0.1$\mu\textrm{m}$의 해상도를 나타냈으며, 자동수평시스템은 120 arcsec 범위에서 larcsec의 해상도를 나타냈다. OFF-AXIS 정렬방식에서는 0.2$\mu\textrm{m}$의 해상도를 가지며, 두빔의 간섭을 이용한 새로운 TTL 정렬은 0.1$\mu\textrm{m}$의 해상도를 나타냈다. 스텝퍼 패턴 실험결과 SAL603레지스트를 사용하였을 때 웨이퍼의 노광후 열처리 $105^{\circ}C$, 60초에서 0.3$\mu\textrm{m}$ Lines and Spaces(L/S)까지 해상되었으며, 0.34$\mu\textrm{m}$ L/S에서 1$\mu\textrm{m}$의 초점심도를 얻을 수 있었다. 마스크 패턴과 레지스트 패턴의 선형성은 0.4$\mu\textrm{m}$ L/S가지 유지 되었다. 또한 XP-89131레지스트의 경우 노광후 열처리 $110^{\circ}C$, 60초에서 0.34$\mu\textrm{m}$ L/S까지 해상됨을 알수 있었다.

• 한국정밀공학회지
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• 제21권9호
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• pp.167-173
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• 2004

The heterodyne He-Ne laser interferometer is the most widely used sensing unit to measure the position error. It measures the positioning error from the displacement of a moving reflector in terms of the wave length. But, the wave length is affected by the variation of atmospheric temperature. Temperature variation of 1$^\circ C$ results in the measuring error of 1ppm. In this paper, for measuring more accurately the position error of the ultra precision stage, the refractive index compensation method is introduced. The wave length of the laser interferometer is compensated using the simultaneously measured room temperature variations in the method. In order to investigate the limit of compensation, the stationary test against two fixed reflectors mounted on the zerodur$\circledR$ plate is performed firstly. From the experiment, it is confirmed that the measuring error of the laser interferometer can be improved from 0.34${\mu}m$ to 0.11${\mu}m$ by the application of the method. Secondly, for the verification of the compensating effect, it is applied to estimate the positioning accuracy of an ultra precision aerostatic stage. Two times of the refractive index compensation are performed to acquire the positioning error of the stage from the initially measured data, that is, to the initially measured positioning error and to the measured positioning error profile after the NC compensation. Although the positioning error of an aerostatic stage cannot be clarified perfectly, it is known that by the compensation method, the measuring error by the laser interferometer can be improved to within 0.1${\mu}m$.

• 대한기계학회논문집A
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• 제34권11호
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• pp.1613-1622
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• 2010

본 연구는 고진공 환경중 초음파 리니어 스테이지의 나노미터 위치제어를 기술하고 있다. 고진공 환경 중 초정밀 위치 제어 시스템에 응용하기 위해 3 차 종진동 모드와 6 차 횡진동 모드를 가지는 BLT를 개발 했다. 안정적인 고출력을 위해 BLT 는 하나의 공진 주파수로 두 개의 모드 진동을 발생 시켜야 한다. 하나의 공진 주파수를 이용 하기 위해 어드미턴스를 변화시켜 각 모드의 공진 주파수를 일치시켜 조건이 다른 대기 환경에서 안정적인 고출력을 얻을 수 있었다. 기압 변화에 따라 구동 특성이 달라지는 시스템을 제어하기 위해 마찰력 변화에 따른 비선형 특성을 보상한 NCTF 제어를 사용했다. 설계된 제어기를 이용해 고진공 환경에서 시스템을 나노미터 정도로 제어하는 결과를 얻을 수 있었다.

• 한국정밀공학회지
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• 제22권5호
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• pp.103-112
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• 2005

This paper presents one-axis high precision scanning system and illustrates the design of modified $X-Y-{\theta}$ stage as a tracker using VCM and commercialized air bearings for it. The scanning system for 100nm resolution is composed of the 3-axis stage and one axis long stroke linear motor stage as a follower. In this study a previous proposed and presented structure of VCM for the fine stage is modified. The tracker has 3 DOF($X-Y-{\theta}$ motions by four VCM actuators which are located on the same plane. So 4 actuating forces are suggested and designed to create least pitch and roll motions. This article will show about the design especially about optimal design. The design focus of this fine stage is to have high acceleration to accomplish high throughput. The optimal design of maximizing acceleration is performed in restrained size. The most sensitive constraint of this optimal design is heat dissipation of coil. There are 5 design variables. Because the relationship between design variables and system parameters are quite complicated, it is very difficult to set design variables manually. Due to it, computer based optimal design procedure using MATLAB is used. Then, this paper also describes the procedures of selecting design variables for the optimal design and a mathematical formulation of the optimization problem. Based on the solution of the optimization problem, the final design of the stage is also presented. The results can be verified by MAXWELL. The designed stage has the acceleration of about 5 $m/s^{2}$ with 40kg total mass including wafer chuck and interferometer mirror. And the temperature of coil is increased $50^{\circ}C$. In addition, the tracker is controlled by high precision controller system with HP interferometer for it and linear scaler for the follower. At that time, the scanning system has high precision resolution about 5nm and scanning resolution about 40nm in 25mm/s constant speed

• 한국산학기술학회논문지
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• 제16권7호
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• pp.4405-4410
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• 2015

두 개의 1차원 주기 패턴을 수직으로 중첩시켜 상하층 패턴으로부터 이축 변위 정보를 각각 디코딩할 수 있는 방법을 제안한다. 투명한 상층 패턴 판별은 굴절률차에 기인한 레이저 빔의 디플렉션 검출을 통해 이뤄지고 하층 패턴 판별은 수광 전압 차의 검출를 통해 이뤄진다. 빌드 업 필름 재질의 상층 패턴은 UV 레이저 가공에 의해 미세가공되고 그리고 알루미늄 하층 패턴은 초정밀 머시닝에 의한 트렌치 가공과 불투명 소재 증착 그리고 폴리싱 과정을 통해 제작된다. 10마이크로미터 간격으로 제작된 샘플 패턴과 이를 인코딩할 수 있는 전용 광학계에 의한 변위 측정 방법은 대면적 스테이지에 장착되어 레이저 간섭계를 이용한 측정데이터와 비교하여 검증된다.