• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.49-59
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• 2004

In this paper the automatic diameter control system of the CZ-150 Crystal Grower is proposed in order to achieve a good performance for the industry applications in MEMC Korea. The effectiveness of the design parameters is verified by means of the computer simulations and the proposed controllers showed the better performance than the conventional PD controllers which always have steady-state errors.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.71-71
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• 2000

In this paper, the fuzzy system is applied to MCZ Crystal Grower using at industrial field. The existing controller, which is PID controller, has a fixed gain and as a result of it it can not have an adaptive control function against the error or disturbance. Hence, the machine operator should always check the process status and when the error is occurred, the quality and the productivity may be decreased by each personal capability. In order to remove this drawback, a fuzzy control system which is known to be adaptive and flexible is applied to the machine. After applying the fuzzy system, and compared with the existing system, the diameter deviation and the defects were decreased. we proved the possibility of application fuzzy system to single silicon crystal grower.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2089-2092
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• 2002

The PID controller have the simple structure and show the comparatively good control performance. Crystal Grower(FF-CZ150) melt polycrystalline silicon at the temperature of about 1450$^{\circ}C$, then grow it into a single crystalline ingot. The automatic diameter control system of the Crystal Grower has a good performance with only PD control. But it contain the integrator in the plant which has a long time delay. In this paper, we show the secondary approximate model and applies time delay controller which has good performance for the plant with long time delay. It will be able to improve the response characteristic against a standard input and a load disturbance.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2799-2802
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• 2003

The automatic diameter control system of the Crystal Grower has a good performance with only PD control. But it contained the integrator the plant which has a long time delay. In this paper. we show the secondary approximate model and applies time delay controller which is good performance for in the long time delay plant. It will be able to improve the response characteristic against a standard input and a load disturbance.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.211-214
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• 2003

본 연구에서는 실리콘 웨이퍼 제조 현장에서 사용 중인 단결정 실리콘 성장기의 자동 직경 제어기를 2계 근사 모델을 이용하여 설계하고 시간지연 보상기를 적용함으로써 결정봉의 직경과 인상 속도를 최적화하여 결정봉의 제품에 직접적인 영향을 주는 결정 결함 및 언더나 오버의 직경 이상을 줄이고 제품의 질과 수율을 향상시킬 수 있다. 또한 기존의 자동직경제어시스템의 고전적인 제어기를 보완함으로써 결과적으로 생산량 증가 및 제품의 질 향상에 이바지를 하고 새로이 요구되는 고객의 신기술 요구에 대한 현 장비의 제한성을 극복하는데 큰 기여를 할 것으로 기대 된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.5
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• pp.356-361
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• 2000

The radial position of OiSF-ring has been meaningful data in industry. Thus it's position was calculated by application of (V/G)/sub crit/ = 0.138 ㎟/minK and point defect dynamics for industrial scale grower with various pull rates. After the calculation, compared with experimental result. OiSF-ring diameters expected with calculation were good agreement with experimental results. In order to show validity of the predicted temperature distribution using STHAMAS which is one of the global simulator for Cz crystal growing, temperature was measured along the axis of crystal using thermocouples, and compared with the calculated temperature. We found the effective thermal conductivity K/sub m/ (r) which gives in accordance with the temperature distribution at the axis of crystal and crystal/melt interface shape between experimental and computational results. Therefore, effective thermal conductivity K/sub m/ (r) was applied instead of solving melt convection problem.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.4
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• pp.620-626
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• 1996

$LiNbO_{3}$ single crystals were grown using a self-designed radio-frequency heating Czochralski crystal grower. Congruently melting composition was used and the optimum growth conditions were established. The compensated power control method was very effective to control the outer diameter of the crystal ingots within ${\pm}5\;%$. Scanning electron microscopy was performed to characterize the effect of the $Mg^{2+}$ ions on the formation of the ferroelectric domain in $LiNbO_{3}$.

• International Journal of Control, Automation, and Systems
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• v.3 no.2
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• pp.252-257
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• 2005

In this work, we propose a simple but efficient method to design a target temperature trajectory for pulling speed tracking control of the crystal grower in the Czochralski crystallization process. In the suggested method, the model predictive control strategy is used to incorporate the complex dynamic effect of the heater temperature on the pulling speed into the temperature trajectory design quantitatively. The feedforward trajectories designed by the proposed method were implemented on 200 mm and 300 mm silicon crystal growers in the commercial Czochralski process. The application results have demonstrated its excellent and consistent tracking performance of pulling speed along whole bulk crystal growth.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.3
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• pp.85-88
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• 2001

High oxygen pressure has been applied for a floating zone (FZ) crystal grower in order to grow high quality $TiO_2$(rutile) single crystals suitable for optical application. The $TiO_2$ crystals, grown under 0.3, 0.4, 0.5, and 0.8MPa oxygen pressure respectively, are all transparent and dark blue. The degree of the presence of sub-grain boundary in the crystal differs from the applied oxygen pressure. In particular, $TiO_2$ single crystals grown under0.5 MPa showed sub-grain boundary-free and estimated good for optical devices.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.185-190
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• 1997

The 6H-SiC single crystals were grown using a self-designed crystal grower by the sublimation method. The grown crystals were typically 30 mm in diameter and 10 mm in length. Optimum growth conditions were established as follows : the temperature of the raw material was $2150~2250^{\circ}C$, the temperature of the substrate was $1950~2050^{\circ}C$, the temperature difference between the raw material and substrate was about $200^{\circ}C$, growth pressure was 50~200 torr and growth rate was 300~700 $\mu\textrm{m}$/hr. Optical microscopy was used for observing the surface of the 6H-SiC single crystal grown and the phenomenological approach was performed on the formation mechanism of the defects in the 6H-SiC crystal. Especially, the micropipes in the as-grown surface were examined to determine the formation mechanisms of the micropipes.