• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2369-2374
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• 2008

In the precision hot plate for wafer processing, the temperature uniformity of upper plate surface is one of the key factors affecting the quality of wafers. Precision hot plates require temperature variations less than ${\pm}1.5%$ during heating to $120^{\circ}C$. In this study, we have manufactured the flat plate heat pipe hot chuck of circle type(300mm) and investigated the operating characteristics of flat plate heat pipe hot chuck experimentally. Various liquids(aceton, FC-40, water) were used as the working fluid and charging ratio was changed($14{\sim}36\;vol.%$). Several cases were tested to improve temperature uniformity. Major working fluid to be investigated was water. Using water, various parameters such as charging ratio, wafer operation on-off time, different working fluids. In case of water, the temperature uniformity was ${\pm}1.5%$, response time of wafer were investigated.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.358-358
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• 2000

An iterative learning control technique based on a linear quadratic optimal criterion is proposed for temperature uniformity control of a silicon wafer in rapid thermal processing.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.9
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• pp.831-835
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• 2000

The uniformity of themperature on a wafer is a wafer is one the most important parameters to conterol the RTF(Rapid Thermal Process) with proper input signals. It is impossible to achieve the uniformity of temperature without the exact estimation of temperature ar all points on the wafer. There fore, it is difficult to understand the internal dynamics as well as the structural complexities of the RTP, which is aprimary obstacle to measure the distributed temperatures on the wafer accurately. Furthermore, it is also hard to accomplish desirable estimation because only a few pyrometers are available in the general equipments. In the paper, a thermal model based on the chamber grometry of the AST SHS200 RTP system is developed to effectively control the thermal uniformity on the wafer. First of all, the estimation method of one-point measurement is developed, which is properly extended to the case of multi-point measurements. This thermal model is validated through simulation and experiments. The proposed work can be utilized to building a run-by -run or a real-time control of the RTP.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.2
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• pp.62-67
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• 2000

The uniformity of temperature on a wafer is one of the most important parameters to control the RTP (Rapid Thermal Process) with proper input signals. Since it is impossible to achieve the uniformity of temperature without exact estimation of temperature at all points on the wafer, the difficulty of understanding internal dynamics and structural complexities of the RTP is a primary obstacle to accurately measure the distributed temperatures on the wafer. Furthermore, it is also hard to accomplish desirable estimation because only few pyrometers have been commonly available in the general equipments. In the paper, a thermal model based on the chamber geometry of the AST SHS200 RTP system is developed to effectively control the thermal uniformity on the wafer. First of all, the estimation method of one-point measurement is developed, which is properly extended to the case of multi-point measurements. This thermal model is validated through certain simulation and experiments. The work can be usefully contributed to building a run-by-run or a real-time controls of the RTP.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.6
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• pp.500-505
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• 2000

This paper deals with wafer temperature uniformity control essential in rapid thermal processing (RTP). One of the important control objectives of RTP is to keep the temperature over the wafer surface as uniformly as possible. For this, a discrete time state equation around the operating point is first identified by using the subspace fitting method, and a multivariable LQG(Linear Quadratic Gaussian) controller is designed based on the identified model. Simulation and experimental results show improvement in temperature uniformity over the conventional PID method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.2
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• pp.149-157
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• 2008

During CVD process of semiconductor wafer fabrication, maintaining the uniformity of temperature distribution at wafer top surface is one of the key factors affecting the quality of final products. Effect of contact conductance between wafer and hot plate on predicted temperature of wafer was investigated. The validity of opaque wafer assumption was also examined by comparing the predicted results with Discrete Ordinate solutions accounting for semitransparent radiative characteristics of silicon. As the contact conductance increases predicted wafer temperature increases and the differences between maximum and minimum temperatures within wafer and between wafer and hot plate top surface temperatures decrease. The opaque assumption always overpredicted the wafer temperature compared to semitransparent calculation. The influences of surrounding reactor inner wall temperature and hot plate configuration are then discussed.

• Journal of the Semiconductor & Display Technology
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• v.8 no.4
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• pp.59-63
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• 2009

This paper presents two dimensional simulation results of an inductively coupled $Ar/O_2$ plasma reactor. The effects of operating conditions on the plasma properties and the uniformity of atomic oxygen near the wafer were systematically investigated. The plasma density had the linear dependence on the chamber pressure, the flow rate of the feed gas and the power deposited into the plasma. On the other hand, the electron temperature decreased almost linearly with the chamber pressure and the flow rate of the feed gas. The power deposited into the plasma nearly unaffected the electron temperature. The simulation results showed that the uniformity of atomic oxygen near the wafer could be improved by lowering the chamber pressure and/or the flow rate of the feed gas. However, the power deposited into the plasma had an adverse effect on the uniformity.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2606-2611
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• 2003

Comprehensive study on the control system design for a RTP process has been conducted. The purpose of the control system is to maintain maximum temperature uniformity across the silicon wafer achieving precise tracking for various reference trajectories. The study has been carried out in two stages: thermal balance modeling on the basis of a semi-empirical radiation model, and optimal iterative learning controller design on the basis of a linear state space model. First, we found through steady state radiation modeling that the fourth power of wafer temperatures, lamp powers, and the fourth power of chamber wall temperature are related by an emissivity-independent linear equation. Next, for control of the MIMO system, a state space modeland LQG-based two-stage batch control technique was derived and employed to reduce the heavy computational demand in the original two-stage batch control technique. By accommodating the first result, a linear state space model for the controller design was identified between the lamp powers and the fourth power of wafer temperatures as inputs and outputs, respectively. The control system was applied to an experimental RTP equipment. As a consequence, great uniformity improvement could be attained over the entire time horizon compared to the original multi-loop PID control. In addition, controller implementation was standardized and facilitated by completely eliminating the tedious and lengthy control tuning trial.

• Journal of the Semiconductor & Display Technology
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• v.15 no.3
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• pp.72-77
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• 2016

As the semiconductor production technology has gradually developed and intra-market competition has grown fiercer, the caliber of Si Wafer for semiconductor production has increased as well. And semiconductors have become integrated with higher density. Presently the Si Wafer caliber has reached up to 450 mm and relevant production technology has been advanced together. Electrostatic chuck is an important device utilized not only for the Wafer transport and fixation but also for the heat treatment process based on plasma. To effectively control the high calories generated by plasma, it employs a refrigerant-based cooling method. Amid the enlarging Si Wafers and semiconductor device integration, effective temperature control is essential. Therefore, uniformed temperature distribution in the electrostatic chuck is a key factor determining its performance. In this study, the form of refrigerant flow channel will be investigated for uniformed temperature distribution in electrostatic chuck.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2512-2517
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• 2007

Effect of natural convention for hot plate surface temperature uniformity was studied by experiments that were adjusted height of chamber and temperature difference. The hot plate chamber is composed of the hot plate and the upper heater and adiabatic vertical wall. The hot plate diameter is 220mm and maintains temperature at $150^{\circ}C$. Flow pattern compares with surface temperature and confirms that natural convection affects on temperature uniformity of hot plate surface. In case, temperature non-uniformity of hot plate surface is due to heater pattern, lots of weak and small flow cells more improve temperature uniformity than stronger flow cells or non-developing flow cell. Improve temperature uniformity $1.2^{\circ}C$ when developing weak and small flow cells.