Over-temperature protection circuit of vertical furnace

Abstract

The utility model discloses an over-temperature protection circuit for a vertical furnace. The over-temperature protection circuit comprises a protection circuit unit and a detection unit, the detection unit comprises a temperature detection module and a detection module, and normally closed switches in the detection module are connected in series to form a control loop; the protection circuit unit comprises a main heating circuit, a heating enabling circuit and an over-temperature protection circuit; the main heating circuit comprises a heating electromagnetic switch; the heating enabling circuit comprises a heating enabling electromagnetic switch; the over-temperature protection circuit comprises an over-temperature protection electromagnetic switch; one end of the control loop is connected with one end of the main heating circuit, and the other end of the control loop is connected with the other end of the main heating circuit; a first normally closed switch of the over-temperature protection electromagnetic switch and a normally open switch of the heating enabling electromagnetic switch are connected in series in the main heating circuit; a second normally-closed switch of the over-temperature protection electromagnetic switch is connected in series in the heating enabling circuit; and a normally open switch of the heating electromagnetic switch is connected in series in the over-temperature protection circuit. The utility model has the advantages of simple structure, reliable protection and the like.

Description

Technical Field

[0001] The utility model mainly relates to the technical field of semiconductor equipment, and in particular to an over-temperature protection circuit for a vertical furnace. Background Art

[0002] The third generation of semiconductor materials is represented by silicon carbide and gallium nitride. Compared with the previous two generations of semiconductor materials, their biggest advantage is that they have a wider bandgap width, which ensures that they can break through higher electric field strengths and are suitable for the preparation of high-voltage and high-frequency power devices. Devices made of silicon carbide materials have the characteristics of high temperature resistance, high voltage resistance, high frequency, high power, and radiation resistance. They have the advantages of fast switching speed and high efficiency, which can greatly reduce product power consumption, improve energy conversion efficiency and reduce product volume, and have a wide range of downstream applications. The manufacturing process of power devices is based on semiconductor science and involves the cross-integration of multiple fields and disciplines such as physics, chemistry, electronics, and materials science. Technologies such as single crystal and crystal epitaxial growth, physical vapor deposition and chemical vapor deposition of multiple thin films, impurity diffusion, thermal oxidation, rapid annealing, high-temperature sintering and alloying all require the use of thermal methods. The wafer and the carrier mechanism are raised from room temperature to the necessary temperature for the process through the heater of the vertical furnace before reacting. For the process reaction process, precise control of temperature has always been very important. Temperature deviation not only affects the final effect of the process, but also has the possibility of causing safety accidents, such as overheating. Taking hydrogen-oxygen synthesis as an example, both hydrogen and oxygen are flammable and explosive. When the reaction temperature between the two gases exceeds the critical value of 850°C, an explosion will occur with a high probability. The safety and reliability of the hydrogen-oxygen synthesis system will directly affect the normal operation of the equipment. Similar situations also exist for various other process equipment. For example, when making thin films at a certain deposition rate, single-crystal silicon thin films can be grown epitaxially under high temperature conditions, while polycrystalline silicon thin films can be obtained under low temperature conditions. The type of film formation is related to the accuracy and range of the temperature. Therefore, from the perspective of equipment process effect and quality safety, it is very necessary to design an over-temperature protection system that is universally applicable to third-generation semiconductor process vertical furnaces. Utility Model Content

[0003] The technical problem to be solved by the utility model is: in view of the technical problems existing in the prior art, the utility model provides a vertical furnace over-temperature protection circuit with a simple circuit structure and reliable protection.

[0004] In order to solve the above technical problems, the technical solution proposed by the utility model is:

[0005] A vertical furnace overtemperature protection circuit comprises a protection circuit unit and a plurality of detection units; each group of detection units corresponds to each temperature zone of the vertical furnace; each detection unit comprises a temperature detection module and a detection module, and the temperature detection module is connected to the detection module; each detection module is provided with a normally closed switch, and the normally closed switches in each detection module are connected in series to form a control loop; the protection circuit unit comprises a controller, a main heating circuit, a heating enable circuit and an overtemperature protection circuit; the main heating circuit comprises a heating electromagnetic switch; the heating enable circuit comprises a heating enable electromagnetic switch; the overtemperature protection circuit comprises an overtemperature protection electromagnetic switch; one end of the control loop is connected to one end of the main heating circuit, and the other end of the control loop is connected to the other end of the main heating circuit; a first normally closed switch of the overtemperature protection electromagnetic switch and a normally open switch of the heating enable electromagnetic switch are connected in series in the main heating circuit; a second normally closed switch of the overtemperature protection electromagnetic switch is connected in series in the heating enable circuit; and a normally open switch of the heating electromagnetic switch is connected in series in the overtemperature protection circuit.

[0006] Preferably, the heating electromagnetic switch is a heating contactor KM1.

[0007] Preferably, the heating enable electromagnetic switch is a heating enable relay K1.

[0008] Preferably, the over-temperature protection electromagnetic switch is an over-temperature protection relay K2.

[0009] Preferably, the temperature detection module is a thermocouple.

[0010] Preferably, the controller is a PLC.

[0011] Preferably, the detection module also includes a display screen.

[0012] Compared with the prior art, the advantages of the utility model are:

[0013] The vertical furnace over-temperature protection circuit of the utility model is provided with a normally closed switch in each detection module, and the switches are connected in series with each other to be connected in series in the main heating circuit. When the corresponding thermocouple in any temperature zone detects over-temperature, the corresponding normally closed switch is disconnected, and then the main heating circuit is disconnected to achieve over-temperature protection; at the same time, when the thermocouple detects over-temperature, the corresponding over-temperature protection relay in the corresponding over-temperature protection circuit is controlled by the PLC to be attracted, and the main heating circuit is controlled to be on and off by the contacts of the over-temperature protection relay, so as to further ensure the over-temperature protection of the main heating circuit; through the comprehensive protection of the above two, safe and reliable over-temperature protection is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a circuit diagram of a protection circuit in an embodiment of the utility model.

[0015] Figure 2 The figure is a circuit diagram of a protection circuit unit in an embodiment of the utility model.

[0016] Legend: 1. Detection unit; 101. Detection module; 102. Temperature detection module; 2. Protection circuit unit; 201. Main heating circuit; 202. Heating enable circuit; 203. Over-temperature protection circuit. DETAILED DESCRIPTION

[0017] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, the vertical furnace over-temperature protection circuit of the embodiment of the utility model includes a protection circuit unit 2 and a plurality of detection units 1, each group of detection units 1 corresponds to each temperature zone of the vertical furnace; each detection unit 1 includes a temperature detection module 102 (such as a thermocouple) and a detection module 101 (such as a detection instrument), and the temperature detection module 102 is connected to the corresponding detection module 101; each detection module 101 is provided with a normally closed switch, and the normally closed switches in each detection module 101 are connected in series to form a control loop;

[0019] The main heating circuit 201 includes a heating electromagnetic switch (such as a heating contactor KM1); the heating enable circuit 202 includes a heating enable electromagnetic switch (such as a heating enable relay K1); the over-temperature protection circuit 203 includes an over-temperature protection electromagnetic switch (such as an over-temperature protection relay K2); one end of the control loop is connected to one end of the main heating circuit 201, and the other end of the control loop is connected to the other end of the main heating circuit 201; the main heating circuit 201 is connected in series with a first normally closed switch of the over-temperature protection relay K2 and a normally open switch of the heating enable relay K1; the heating enable circuit 202 is connected in series with a second normally closed switch of the over-temperature protection relay K2; and the over-temperature protection circuit 203 is connected in series with a normally open switch of the heating contactor KM1.

[0020] Specifically, for detection instruments, such as PLC, etc., its function is to convert the millivolt voltage signal transmitted by the thermocouple into a digital signal through analog / digital quantity, and display it on the LCD screen.

[0021] like Figure 1 As shown, for example, for a furnace tube with five temperature zones, each instrument is connected in parallel with a DC 24V power supply, and the normally closed switches in the detection instruments are connected in series. Each detection instrument has a matching thermocouple, so for a vertical furnace with N temperature zones, there will be N detection instruments and N thermocouples.

[0022] like Figure 2As shown, the main heating circuit 201 adopts single-phase AC power supply, and the live wire passes through the auxiliary normally closed contact 2 and 3 of the temperature protection relay K2 and the auxiliary normally closed contact 2 and 3 of the heating enable relay K1, and then connects to the coil A1 end of the heating contactor KM1. Since the heating needs to be stopped when the temperature is over, Figure 1 The unconnected pin (pin 11) of the switch in the first detection instrument J1 is connected to the neutral line of the single-phase AC power, and the unconnected pin (pin 12) of the switch in the fifth instrument J5 is connected to the coil A2 end of the heating contactor KM1.

[0023] The weak current parts of the heating enable circuit 202 and the over-temperature protection circuit 203 are powered by 24V. In the heating enable circuit 202, the auxiliary normally closed contact 7 of the over-temperature protection relay K2 is connected to the 24V DC voltage, and then the contact 6 of the over-temperature protection relay K2 is connected to the slave contact 8 of the heating enable relay K1, and finally connected to the PLC through the main contact 1 of the heating enable relay;

[0024] In the over-temperature protection circuit 203, the auxiliary normally open contact 13 of the heating contactor KM1 is connected to a 24V DC voltage, the other contact 14 is connected to the slave contact 8 of the over-temperature protection relay K2, and the main contact 1 of the over-temperature protection relay K2 is connected to the PLC.

[0025] In specific applications, when the five temperature zones are all below the critical temperature value, the switches in each detection instrument are normally closed, and the PLC closes the heating enable circuit 202. At this time, the heating enable relay K1 is energized, and the 3-4 terminals of K1 are closed. The main heating circuit 201 is turned on, and the main contact of the heating contactor KM1 is energized. The auxiliary contacts 13 and 14 are in a closed state. At this time, the over-temperature protection circuit 203 is not turned on (the switch inside the PLC is in the off state), and the auxiliary contacts 6 and 7 of the over-temperature protection relay K2 in the heating enable circuit 202 remain normally closed, and the main contact of the heating enable relay K1 is energized, and the upper computer program interface will display that the heating is normal.

[0026] If the temperature of any one of the five temperature zones is higher than the critical temperature value, on the one hand, the PLC will output a signal to turn on the over-temperature protection circuit 203, so that K2 is energized, and the corresponding K2 contact 2-3 end connected in series in the main heating circuit 201 is disconnected, so that KM1 is disconnected; at the same time, the K2 contact 6-7 end connected in series in the heating enable circuit 202 is disconnected; at the same time, if the temperature of any one of the temperature zones is higher than the critical temperature value, the normally closed switch inside the detection instrument corresponding to the temperature zone will be disconnected, so that the main heating circuit 201 where the heating contactor KM1 is located is disconnected, and an over-temperature alarm is displayed on the upper computer interface. Since the switches inside each detection instrument are connected in series with each other, when the line is disconnected, the heating will stop; if the heating is to be resumed, the switch needs to be reset by pressing the button on the detection instrument. Of course, in other embodiments, no matter how many temperature zones a single furnace tube has, the control loop is unique.

[0027] The vertical furnace over-temperature protection circuit 203 of the utility model is provided with a normally closed switch in the detection module 101, and the switches are connected in series with each other to be connected in series in the main heating circuit 201. When the corresponding thermocouple in any temperature zone detects over-temperature, the corresponding normally closed switch is disconnected, and then the main heating circuit 201 is disconnected to achieve over-temperature protection; at the same time, when the thermocouple detects over-temperature, the corresponding over-temperature protection relay in the corresponding over-temperature protection circuit is controlled by PLC to be energized, and the main heating circuit 201 is controlled to be on and off through the contacts of the over-temperature protection relay, so as to further ensure the over-temperature protection of the main heating circuit 201; through the comprehensive protection of the above two, safe and reliable over-temperature protection is achieved.

[0028] The above are only preferred implementations of the utility model. The protection scope of the utility model is not limited to the above embodiments. All technical solutions under the idea of ​​the utility model belong to the protection scope of the utility model. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the utility model should be regarded as the protection scope of the utility model.

Claims

1. A vertical furnace over-temperature protection circuit, characterized in that: The invention comprises a protection circuit unit (2) and a plurality of detection units (1); each detection unit (1) corresponds to a temperature zone of a vertical furnace; each detection unit (1) comprises a temperature detection module (102) and a detection module (101), and the temperature detection module (102) is connected to the detection module (101); each detection module (101) is provided with a normally closed switch, and the normally closed switches in each detection module (101) are connected in series to form a control loop; the protection circuit unit (2) comprises a controller, a main heating circuit (201), a heating enabling circuit (202) and an over-temperature protection circuit (203); the main heating circuit (201) The invention comprises a heating electromagnetic switch; the heating enabling circuit (202) comprises a heating enabling electromagnetic switch; the over-temperature protection circuit (203) comprises an over-temperature protection electromagnetic switch; one end of the control loop is connected to one end of the main heating circuit (201), and the other end of the control loop is connected to the other end of the main heating circuit (201); a first normally closed switch of the over-temperature protection electromagnetic switch and a normally open switch of the heating enabling electromagnetic switch are connected in series in the main heating circuit (201); a second normally closed switch of the over-temperature protection electromagnetic switch is connected in series in the heating enabling circuit (202); and a normally open switch of the heating electromagnetic switch is connected in series in the over-temperature protection circuit (203).

2. The vertical furnace over-temperature protection circuit according to claim 1, characterized in that: The heating electromagnetic switch is a heating contactor KM1.

3. The vertical furnace over-temperature protection circuit according to claim 2, characterized in that: The heating enable electromagnetic switch is a heating enable relay K1.

4. The vertical furnace over-temperature protection circuit according to claim 2, characterized in that: The over-temperature protection electromagnetic switch is an over-temperature protection relay K2.

5. The vertical furnace over-temperature protection circuit according to any one of claims 1 to 4, characterized in that: The temperature detection module (102) is a thermocouple.

6. The vertical furnace over-temperature protection circuit according to any one of claims 1 to 4, characterized in that: The controller is a PLC.

7. The vertical furnace over-temperature protection circuit according to any one of claims 1 to 4, characterized in that: The detection module (101) also includes a display screen.

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