JPH0433112A - Heater controller - Google Patents

Abstract

PURPOSE:To prevent an overcurrent from flowing in a heater when the setting temperature of the heater is altered to a high temperature by detecting that the overcurernt flows in the heater by means of the deviation signal of a temperature controller and setting the maximum output of a power controller to be smaller than a setting output value for prescribed time. CONSTITUTION:For controlling the temperature of the heater 2, a slope setting unit 9 sets the maximum output and the temperature slope of the power controller 8. A target temperature is set by operating the temperature controller 4. When the target temperature of the heater 2 is altered to high, a relay contact point 5 in the internal part of the temperature controller 4 is turned off and the deviation signal (b) is turned off since a detection temperature by a thermocouple 3 is beyond the range of a proportional band. At that time, the temperature controller 4 gives an instruction to supply power to the heater 2 by the maximum out put to the power controller 8, When a contact point signal (a) detects that the contact point 5 is turned off, a sequencer 6 detects an overcurrent and turns off the excitation of a relay coil 7 for a prescribed period (t). Thus, a relay contact point 12 is turned off, a resistance 10 is inserted and the output of the controller 8 becomes small. Consequently, the overcurrent flowing by overshooting and the like at the time of altering the setting temperature can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a heater control device, and in particular to a device for preventing overcurrent from flowing through the heater when controlling the heater used in a WtM forming device or the like. Regarding.

[Conventional technology]

A heater for heating a substrate is provided in a film forming chamber of a thin film forming apparatus or the like. This heater is provided, for example, in a substrate holder that holds a substrate, and is controlled so that the substrate held by the substrate holder maintains a constant temperature during film formation.

Temperature control of the heater is performed using a temperature control needle and a power controller. That is, first, an operator sets the temperature gradient of the power controller to a predetermined characteristic and turns on the power controller. Then, power is supplied from this power controller to the heater, and the substrate holder containing the heater is heated. The temperature near the heater is detected by a thermocouple,
The detection output of this thermocouple is input to a temperature controller installed outside the film forming chamber. The temperature control needle is PIDi! lJm and outputs a control signal to the power controller. Based on this control signal, the output of the power controller is controlled according to a preset gradient characteristic.

At this time, the maximum output of the power controller is determined by the set slope characteristic.

[Problem to be solved by the invention]

As mentioned above, when controlling the temperature of the heater using a temperature control needle and a power controller, for example, if the target temperature is set to 200°
When set to C, the temperature controller generates a deviation signal from the target temperature and the detected temperature of the heater in the proportional band near 200°C, and proportional control is performed based on this deviation signal.

However, if the target temperature is changed to 300℃, for example, 2
The temperature that was maintained within the proportional band near 00°C is far outside the proportional band for the changed target temperature (300°C), so the temperature controller's deviation signal is turned off. A command is output to the power controller to provide maximum power to the heater. Then, the maximum voltage in the gradient characteristic set in the power controller is temporarily applied to the heater, and an overcurrent is supplied. This causes an overshoot and increases the time required to control the temperature to the target temperature. or may have an adverse effect on the power controller.

A second object of the invention is to provide a heater control device that can prevent overcurrent from flowing through the heater when the set temperature of the heater is changed to a high temperature.

[Means to solve the problem]

A heater control device according to the present invention includes a temperature controller, a power controller, overcurrent detection means, and control means.

The temperature control needle generates a deviation signal from the target temperature and the detected temperature of the heater, and outputs a control signal based on this deviation signal. The power controller controls the power supplied to the heater based on a control signal from the temperature controller. The overcurrent detection means detects that an overcurrent flows through the heater based on a deviation signal of the temperature control needle,
The control means is for making the maximum output of the power controller smaller than a preset output value for a predetermined period based on the detection result of the overcurrent detection means.

[Effect]

In the present invention, when the target temperature of the temperature controller is changed to a higher temperature, the deviation signal of the temperature controller turns off, and this is detected by the overcurrent detection means. When the overcurrent detection means detects that an overcurrent flows through the heater, the maximum output of the power controller is set to be smaller than a preset output value for a certain period of time. After this fixed period has elapsed, the maximum output of the power controller is returned to its original state, and normal heater temperature control is performed.

As a result, even when the heater temperature is set high, an output smaller than the maximum output of the power controller is supplied to the heater for a certain period from that point onward. Therefore, it is possible to prevent overshoot from occurring and adverse effects on the power controller due to overcurrent.

〔Example〕

FIG. 1 is a block circuit diagram of a heater control device according to an embodiment of the present invention.

For example, a heater 2 for heating a substrate is provided in a film forming chamber 1 of a film forming apparatus. A thermocouple 3 is provided near the heater 2 to indirectly detect the substrate temperature. The thermocouple 3 is connected to a temperature controller 4. The temperature controller 4 can set a target temperature from the outside, and generates a deviation signal by comparing the detected temperature from the thermocouple 3 with the target temperature, and outputs a control signal based on this deviation signal. This is what is output. The deviation signal of the temperature controller is generated by turning on the internal relay contact 5, and the turning on and off of this relay contact 5 is sent to the sequencer 6 as a contact signal a.
has been entered. A relay coil 7 is connected to the sequencer 6 and is controlled by the state of the setting signal a.

On the other hand, electric power is supplied to the heater 2 from a power controller 8. IT power controller includes
A control signal from the temperature controller 4 is input, and the power supplied to the heater 2 is controlled by phase control using a thyristor.
am. Also, the power controller 8
There is always a constant voltage between the terminals T1 and 13, and the maximum output is determined by the voltage between the terminals T1 and 12. The voltage between the terminal TI and the terminal 12 can be set by an operator from the outside using a slope setting device 9. Furthermore, terminal TI and terminal 13 of power controller 8
A parallel circuit of a resistor 10 and a relay contact 12 is inserted between them. The relay contact 12 is controlled on and off by the relay coil 7. When this relay contact 12 is turned on, the maximum output of the power controller is
As shown in the figure, it becomes Vl, and when the relay contact 12 is off, it becomes ■2, which is lower than ■1.

The relay coil 7 is deenergized only for a certain period (period t in FIG. 2) after the sequencer 6 receives the contact signal a.

Next, the operation will be explained.

When controlling the heater temperature, first the gradient characteristics are set using the gradient setting device 9. As a result, the maximum output and temperature gradient of the power controllers 7 to 8 are set. Further, the target temperature of the substrate is set by operating the temperature controller 4.

For example, if the target temperature is set to 200°C, the temperature controller 4
compares this target temperature 200''C with the temperature detected by the thermocouple 3, and outputs a control signal to the power controller 8 based on the comparison result. If the temperature is sufficiently low, a control signal is output to the power controller 8 to supply power to the heater 2 at maximum output.When the heater temperature falls within the proportional band around the target 200°C, , the relay contact 5 inside the temperature controller 4 is turned on and a deviation signal is generated.The temperature controller 4 performs proportional control based on this deviation signal.
The heater 2 is maintained at a temperature around 200°C. In addition,
In this state, the relay coil 7 is energized and the relay contact 1
2 is on.

Next, from the above state, set the target temperature of the heater to 300.
When changing to °C, the detected temperature (approximately 200 °C) is outside the proportional band relative to 300 °C, so the relay contact 5 inside the temperature controller 4 is turned off, and the deviation signal is turned off. becomes. At this time, the temperature controller 4 instructs the power controller 8 to supply power to the heater 2 at the maximum output.

At this time, it is detected by the contact signal a that the relay contact 5 inside the temperature controller 4 is turned off. The sequencer 6 is
This contact signal a turns off the excitation of the relay coil 7 for the period shown in FIG. This allows relay contact 1
2 is off (open) as shown in FIG. Then, the voltage between the terminal TI and the terminal 12 is changed as the relay contact 12 is turned on (
It is smaller by the amount that the resistor 10 is inserted compared to the case of (closed). Therefore, the heater voltage in this case is 2 as shown in FIG. 2, and the heater 2 is heated by this voltage 2.

After a period of time has elapsed since receiving the contact signal a, the sequencer 6 re-energizes the relay coil 7 and turns on the relay contact 12. As a result, the voltage between the terminals TI and T2 of the power controller 8 becomes the state initially set by the slope setting device 9, and thereafter the substrate temperature is adjusted to 3 by the normal heater control 6.
Maintain at 00°C.

In this embodiment, even when the heater temperature is set high, current is supplied to the heater 2 with a characteristic like P2, as shown in FIG. As is obvious, overcurrent can be prevented.

In the above embodiments, the present invention was applied to heater control of a film forming apparatus, but it can be similarly applied to heater temperature control of other apparatuses.

[Effects of the Invention] As described above, in the present invention, when the set temperature is changed, the deviation signal of the temperature controller detects the overflow of the heater, and the maximum output of the power controller is determined from this detection result. Since the current is reduced for a predetermined period of time, overcurrent flowing when changing the set temperature can be prevented.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of a heater control device according to an embodiment of the present invention, FIG. 2 is a diagram showing the characteristics of the heater voltage when changing the temperature setting in the device, and FIG. 3 is a diagram showing the characteristics of the heater voltage when changing the temperature setting in the device. It is a figure which shows the current characteristic at the time of doing so. 2... Heater, 3... Thermocouple, 4... Temperature controller, 5
... Relay contact, 6... Sequencer, 7... Relay coil, 8... Power controller, 9... Gradient setter, 10... Resistor, 2... Relay contact.

Claims (1)

[Claims] (1) A temperature controller that generates a deviation signal from the target temperature and the detected temperature of the heater and outputs a control signal based on this deviation signal; and a control signal from the temperature controller to control the power supplied to the heater. a power controller configured to detect overcurrent flowing through the heater based on a deviation signal from the temperature controller; A heater control device comprising: a control means for making the output value smaller than the output value for a predetermined period of time;