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| ==Temperature Measurement and Control== | | ==Temperature Measurement and Control== |
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| The temperature of the substrate can be controlled by use of either a thermocouple (TC) or an optical pyrometer (Pyro). This control system is called the closed loop mode, i.e. the temperature control mode. An open loop mode (power control mode), on the other hand, is not recommended. In this case, the temperature of the substrate would vary according to the power emitted by the lamps established as setpoint, without any limiting check from the pyrometer or thermocouple. Thus, it can happen that the chamber is heated up very fast with no actual temperature control, which can induce serious damages to the tool. | | The temperature of the substrate can be controlled by two different modes. The preferred one is called the closed loop mode, i.e. the temperature control mode (pyrometer or thermocouple control). On the other hand, an open loop mode (power control mode), although possible, is not recommended to be used as default. In the latter, the temperature of the substrate would vary according to the power emitted by the lamps that is established as setpoint, without any limiting check from the pyrometer or thermocouple. Thus, it can happen that the chamber is heated up very fast with no actual temperature control, which can induce serious damages to the tool. |
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| When using the temperature control mode, the thermocouple is usually the recommended sensor. However, this recommendation varies a lot depending on the desired conditions for the process. See the table below.
| | In RTP2 Jipelec, the pyrometer (Pyro1) is used as the default control sensor and it is always present. The thermocouples are not intended to be used for high-temperature processes - at 1000 °C or above - as a lifetime reduction can be expected if they are used in such conditions. As such, the thermocouple (TC1) should only be mounted and used as temperature control if the process temperature ranges RT to 150 °C. Mounting the thermocouples must only be carried out by the responsible persons - users do not need to know how to do it. |
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| {| border="1" cellspacing="5" cellpadding="10" ;" align="center"
| | Nonetheless, while processing, it is possible to have up to three thermocouples measuring the temperature - TC1, TC2 and TC3 - in conjugation with the optical pyrometer. A short description of each component can be found below. |
| !Colspan="2" style="background:silver; color:black;" align="center"|
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| |style="background:WhiteSmoke; color:black;" align="center"|<b>RT to 400 °C</b>
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| |style="background:WhiteSmoke; color:black;" align="center"|<b>400 °C to 850 °C</b>
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| |style="background:WhiteSmoke; color:black;" align="center"|<b>850 °C to 1000 °C</b>
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| |style="background:WhiteSmoke; color:black;" align="center"|<b>1000 °C to 1200 °C</b>
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| !style="background:Silver; color:black" align="center" align="center" rowspan="2"|Pressure conditions
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| |style="background:Silver; color:black"|Vacuum
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| |style="background:WhiteSmoke; color:black;" align="center"|TC control
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| |style="background:WhiteSmoke; color:black;" align="center"|Pyro control
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| |style="background:WhiteSmoke; color:black;" align="center"|Pyro control
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| |style="background:WhiteSmoke; color:black;" align="center"|Pyro control*
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| |style="background:Silver; color:black"|No Vacuum
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| |style="background:WhiteSmoke; color:black;" align="center"|TC control
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| |style="background:WhiteSmoke; color:black;" align="center"|TC control
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| |style="background:WhiteSmoke; color:black;" align="center"|TC control
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| |style="background:WhiteSmoke; color:black;" align="center"|Pyro control*
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| |-
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| |}
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| '''*Important!''' The thermocouples are not intended to be used for high-temperature processes - a lifetime reduction can be expected if they are used in such conditions. Therefore, when processing at 1000 °C or above, the thermocouples must be pulled down. Consequently, the pyrometer should be chosen as the temperature control method in the recipe. These changes to the thermocouples should only be carried out by the responsible persons. | | *'''TC1 (optional)''' - This is called the control thermocouple, only mounted when temperatures ranging RT to 150 °C are needed. When using a susceptor, it corresponds to a long, thin TC that is placed in a hole at the edge of the susceptor. On the other hand, if a wafer is directly placed on top of the quartz pins or a carrier wafer is being used, it is not possible to use this long TC. Thus, TC1 corresponds to a thick TC positioned in contact with the back of the wafer/carrier, approximately in the center. Regardless its type, it is very important that the TC is placed correctly and that contact with the substrate is ensured, otherwise the temperature measurement will not be correct. |
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| | *'''TC2 and TC3 (uniformity calibrations, optional)''' - These are reference TCs, these do not control the temperature and do not need to be present. They can be placed in six other positions across the platen (see image in section 6.2), in conjugation to TC1. These TCs can be used to measure the temperature uniformity over a wafer or susceptor. However, the temperature measurement, and ultimately the uniformity interpretation, will always be very dependent on the quality of the contact between each TC and the wafer or susceptor. |
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| While processing, it is possible to have three thermocouples measuring the temperature - TC1, TC2 and TC3 - in conjugation with the optical pyrometer.
| | *'''Optical Pyrometer (mandatory)''' - The pyrometer is making an non-contact optical temperature measurement in the center of the susceptor or wafer. To ensure that the temperature measured by the pyrometer is correct, a temperature calibration must be done, for which the TC1 is used as a reference. To get the most correct temperature measurement, a pyrometer calibration should be done for each substrate type (thickness, size, material, etc.). |
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| *'''TC1''' - This is called the control thermocouple, and when possible, it should always be connected. When using a susceptor, it corresponds to a long, thin TC that is placed in a hole at the edge of the susceptor. On the other hand, if a wafer is directly placed on top of the quartz pins or a carrier wafer is being used, it is not possible to use this long TC. Thus, TC1 corresponds to a thick TC positioned in contact with the back of the wafer/carrier, approximately in the center. Regardless its type, it is very important that the TC is placed correctly and that contact with the substrate is ensured, otherwise the temperature measurement will not be correct.
| | The machine has a PID regulator for the temperature control. For each substrate type, thickness, size, material and desired process these PID settings have to be optimized in order to ensure that the actual temperature matches the settings as good as possible and no damage is induced to the tool while processing. |
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| *'''TC2 and TC3''' - These are reference TCs and can be placed in other six positions in the platen. They are not controlling the temperature, and they do not need to be present. The TCs can for instance be used to measure the temperature uniformity over a wafer or susceptor. However, the temperature measurement, and ultimately the uniformity interpretation, will always be very dependent on the quality of the contact between each TC and the wafer or susceptor.
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| *'''Optical Pyrometer''' - The pyrometer is making an non-contact optical temperature measurement in the center of the susceptor or wafer. To ensure that the temperature measured by the pyrometer is correct, a temperature calibration must be done, for which the TC1 is used as a reference. To get the most correct temperature measurement, a pyrometer calibration should be done for each substrate type, thickness, size, material and each desired process.
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| The machine has a PID regulator for the temperature control. For each substrate type, thickness, size, material and desired process these PID settings have to be optimized in order to ensure that the actual temperature matches the settings as good as possible and no damage is induced to the tool while processing. | |
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| ==Samples and Process Specifications== | | ==Samples and Process Specifications== |
