JP6831965B1 - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor capable of measuring a temperature with high accuracy while suppressing a cost. SOLUTION: A temperature sensor 100 of the present invention is composed of a thermocouple 2 having a pair of thermocouple strands having a joint point as a temperature sensitive portion 6 and being composed of different types of conductors, and one end thereof is composed of the same type of conductor. An extension body 3 having a pair of extension wire 11 connected to the thermocouple wire on the opposite side to the side where the temperature sensitive portion 6 is located and the other end connected to the measuring instrument 50, and a thermocouple. A temperature measuring body 4 provided at a position overlapping the connecting portion 13 of the wire and the extension body wire 11, and the temperature of the temperature sensing unit 6 is set based on the temperature of the connecting portion 13 measured by the temperature measuring body 4. It is measured. [Selection diagram] Fig. 1

Description

The present invention relates to a temperature sensor.

Conventionally, a thermocouple has been used as a temperature sensor for measuring the temperature at a predetermined part. For example, in an apparatus used in the manufacturing process of a semiconductor device (such as a high temperature chamber), it is important to heat the wafer at an appropriate temperature. Therefore, in terms of process control, the temperature is measured at a predetermined part in the apparatus. .. As a temperature sensor used in such a case, Patent Document 1 discloses a wafer-type temperature sensor in which a temperature-sensitive portion of a thermocouple is embedded in a wafer. Such a temperature sensor is connected to a measuring instrument installed outside the semiconductor-related device, and the temperature is measured by this measuring instrument.

In semiconductor-related equipment, since the heated portion has a high temperature (for example, 600 ° C. or higher), an R thermocouple having high heat resistance is used for the temperature sensor. In the R thermocouple, a platinum rhodium alloy is used for the thermocouple strand on the + pole side, and platinum is used for the thermocouple strand on the-pole side. Rhodium and platinum are very expensive, and as the number of measurement points increases, the number of thermocouples required also increases, so this type of temperature sensor has a problem of high cost. Further, in recent years, wafers having an outer diameter of about φ300 mm have become the mainstream, the wafer size is larger than before, and the equipment is also larger. That is, since the measuring instrument is separated from the part where the temperature is measured, the length of the required thermocouple becomes long, which leads to a further cost increase.

In consideration of such a point, conventionally, as shown in Patent Documents 2 and 3, it is common to connect the thermocouple and the measuring instrument with a compensating lead wire. Since the compensating lead wire is cheaper than the thermocouple, the cost can be reduced as compared with the case where the compensating lead wire is composed of only the thermocouple.

By the way, a thermocouple is a closed circuit in which both ends of a pair of thermocouple strands composed of different types of conductors are joined to form a closed circuit, and the temperature is measured based on the thermoelectromotive force generated by the temperature difference at the joining point. .. Specifically, the junction point on the opposite side of the junction point (temperature sensitive part) for measuring the temperature is kept at 0 ° C., and the thermoelectromotive force generated at that time is measured with a voltmeter, and the thermoelectromotive force known in advance is measured. The basic measurement principle is to derive the temperature at the temperature sensitive part based on the relationship between electric force and temperature. However, since it is difficult to maintain the thermocouple junction at 0 ° C. during measurement, a measuring instrument generally provided with a compensation circuit (cold contact compensation circuit) as described in Patent Document 2. To use. According to such a measuring instrument with a compensation circuit, the temperature of the temperature sensing portion can be directly displayed on the measuring instrument without keeping the junction point on the side opposite to the temperature sensing portion at 0 ° C.

FIG. 3 shows a wafer-type temperature sensor 200 configured based on the above-mentioned prior art. The temperature sensor 200 includes a wafer 201, a plurality of thermocouples 203 in which a temperature-sensitive portion 202 is fixed to the wafer 201, and a compensating lead wire 204 connected to each of the thermocouples 203. Further, the compensating lead wire 204 is used by connecting to a measuring instrument 206 including a compensating circuit 205. According to such a temperature sensor 200, the temperature of the portion of the wafer 201 where the temperature sensitive portion 202 is provided can be directly displayed on the measuring instrument 206.

Japanese Unexamined Patent Publication No. 2013-172050 Japanese Unexamined Patent Publication No. 11-351973 JP-A-2007-329215

By the way, although a special product corresponding to the type of thermocouple is prepared for the compensation lead wire, the measurement accuracy is inferior to that of the thermocouple. For example, in class 1 of an R thermocouple, the temperature tolerance is ± 1 ° C., but the temperature tolerance of the corresponding compensating lead wire is about ± 5 ° C. Therefore, when a compensating lead wire is used, the high measurement accuracy of the thermocouple is impaired by the compensating lead wire.

In view of such conventional problems, it is an object of the temperature sensor of the present invention to enable highly accurate temperature measurement while suppressing the cost.

The present invention relates to a thermocouple having a pair of thermocouple strands having a temperature-sensitive portion at a junction, which is composed of different types of conductors, and one end of which is composed of the same type of conductor and has the same feeling as the thermocouple strand. An extension body having a pair of extension element wires connected to the measuring instrument at the other end connected to the side opposite to the side where the temperature part is located, and a connection portion between the thermocouple element wire and the extension body element wire. temperature at the temperature sensing unit based on the temperature from the surface of the connection portion against and a temperature measuring member provided in the direction viewed from a position overlapping towards the rear face, of the connecting portions measured by said temperature measuring body Is a temperature sensor that measures.

Such a temperature sensor includes a plurality of the thermocouple strands and the extension strands in a pair, the plurality of connection portions, and a heat equalizing plate provided across the plurality of connection portions. Is preferable.

Further, the extension wire is preferably formed of copper or an alloy containing copper as a main component.

Further, the extension body is a flat cable, and the flat cable includes a conductor foil for a thermocouple as the wire of the extension body, and a conductor foil for a temperature measuring body that connects the temperature measuring body and the measuring instrument. , The conductor foil for the thermocouple and the insulating film provided with the conductor foil for the temperature measuring body are preferably included.

In the temperature sensor of the present invention, the thermocouple and the measuring instrument are connected by an extension body, and the length of the thermocouple can be minimized, so that the cost can be suppressed. Further, a temperature measuring body is provided at the connecting portion between the thermocouple wire and the extension wire, and the temperature of the temperature sensitive portion can be measured based on the temperature of the connecting portion measured by the temperature measuring body. That is, since the influence of the temperature tolerance of the compensating lead wire is eliminated when measuring the temperature of the temperature sensitive portion, it is possible to realize the temperature measurement with high accuracy.

It is a schematic diagram which showed the 1st Embodiment of the temperature sensor which concerns on this invention. It is a schematic diagram which showed the 2nd Embodiment of the temperature sensor which concerns on this invention. It is a schematic diagram of a conventional temperature sensor in which a thermocouple and a measuring instrument are connected by a compensating electric wire.

First, with reference to FIG. 1, a first embodiment of the temperature sensor according to the present invention and an embodiment of a measuring instrument to which the temperature sensor is connected will be described.

The temperature sensor 100 of the present embodiment measures the temperature inside the semiconductor-related device. As shown in the figure, the temperature sensor 100 includes a wafer 1, a thermocouple 2, a flat cable 3, a temperature measuring body 4, and a heat equalizing plate 5, and is used by connecting to the measuring instrument 50.

The wafer 1 is a dummy wafer having the same diameter as the actual wafer used as a semiconductor device. As shown in the figure, the wafer 1 has a circular thin plate shape, and is formed of, for example, a silicon wafer obtained by thinly slicing a cylindrical ingot made of silicon as a material. The wafer 1 is not limited to a silicon wafer, and is formed of various materials such as a silicon carbide wafer, a sapphire wafer, and a compound semiconductor wafer.

The thermocouple 2 is formed by joining two different types of thermocouple strands to each other and using the joining point as the temperature sensitive portion 6. The thermocouple 2 of the present embodiment is an R thermocouple capable of measuring the temperature in a high temperature environment, and a platinum rhodium alloy is used for the thermocouple wire on the + pole side, and the thermocouple wire on the-pole side. Platinum is used for. The thermocouple 2 is not limited to the R thermocouple, and can be replaced with another type of thermocouple depending on the purpose of use.

The temperature sensor 100 of the present embodiment includes a plurality of thermocouples 2, and the temperature-sensitive portions 6 of each thermocouple 2 are attached to the wafer 1 in a dispersed state as shown in the drawing. The temperature-sensitive portion 6 of the present embodiment is provided with a recess 7 having a shallow depth on the surface of the wafer 1, and is fixed to the wafer 1 with an adhesive inside the recess 7. The temperature sensitive portion 6 may be directly fixed to the surface of the wafer 1 without providing the recess 7. Further, a cover for covering the temperature sensitive portion 6 may be prepared and fixed to the wafer 1 with the temperature sensitive portion 6 covered with the cover.

As shown in the figure, the thermocouples 2 of the present embodiment are arranged on the front side of the wafer 1 from the respective temperature sensitive portions 6 toward the housing 8 so as not to intersect each other. The housing 8 covers each thermocouple 2 and is fixed to the wafer 1. Even if a force is applied to the thermocouple 2 from the outside of the wafer 1, the force acts on the temperature sensitive portion 6. It functions so that it does not (force is hard to act). The housings 8 are arranged in a row as shown in the drawing, and the plurality of thermocouples 2 are pulled out from the housing 8 in a row toward the outside in the radial direction of the wafer 1.

The thermocouple 2 pulled out to the outside of the wafer 1 is connected to one end of the flat cable 3. The flat cable 3 has a long shape, although the middle is omitted in FIG. 1, and the other ends are connected to the measuring instrument 50. The flat cable 3 of the present embodiment is a so-called FPC (Flexible Printed Circuit) or FFC (Flexible Flat Cable), and a conductor foil 10 having a predetermined pattern is provided on the surface of the insulating film 9. It is a thing. In this embodiment, the insulating film 9 is made of polyimide in consideration of heat resistance, but if the usage environment is not so high, a PET (polyethylene terephthalate) film may be used. .. Further, the conductor foil 10 is preferably formed of copper or an alloy containing copper as a main component in order to reduce the cost, but other materials (for example, nickel) may be used. The conductor foil 10 may be provided on only one side of the insulating film 9, or may be provided on both sides. Further, a plurality of insulating films 9 and conductor foils 10 may be laminated to form a multilayer structure. Further, the flat cable 3 is provided with a coverlay that covers the outermost conductor foil 10. The coverlay used for the flat cable 3 is not particularly limited, and various types such as a print coverlay and a film coverlay can be adopted.

The conductor foil 10 of the present embodiment electrically connects the thermocouple conductor foil 11 that electrically connects the thermocouple wire of the thermocouple 2 and the measuring instrument 50, and the temperature measuring body 4 and the measuring instrument 50. It is provided with a conductor foil 12 for a temperature measuring body. The flat cable 3 of the present embodiment is provided with a portion (land or connection terminal) at one end thereof (the end on the side close to the thermocouple 2) where the conductor foil 11 for the thermocouple is exposed without being covered by the coverlay. At this site, the thermocouple strands of the thermocouple 2 are soldered to the thermocouple conductor foil 11 to electrically connect the two. Here, the portion where the thermocouple wire of the thermocouple 2 and the conductor foil 11 for the thermocouple are connected is referred to as a connecting portion 13. The connecting portions 13 of the present embodiment are provided so as to form a row in the lateral direction of the flat cable 3. Although FIG. 1 shows a state in which the connecting portions 13 are arranged in a row, the arrangement of the connecting portions 13 is not limited to this. For example, the positions of the adjacent connecting portions 13 may be staggered in the longitudinal direction, and a plurality of rows may be arranged in the lateral direction of the flat cable 3. The thermocouple conductor foil 11 described above corresponds to the “extended body wire” described in the present specification and the like.

Although not shown, in order to electrically connect the thermocouple conductor foil 11 and the temperature measuring body conductor foil 12 to the measuring instrument 50, the thermocouple conductor foil is attached to the other end of the flat cable 3. A portion (connection terminal) where the 11 and the conductor foil 12 for the temperature measuring body are exposed without being covered by the coverlay may be provided, or a connector electrically connected to the measuring instrument 50 may be attached.

The temperature measuring body 4 is provided at a position overlapping the connecting portion 13. The temperature measuring body 4 may be provided on the same surface (front surface of the flat cable 3) as the surface provided with the connecting portion 13 (for example, the front surface of the flat cable 3), or on the opposite surface (back surface of the flat cable 3). It may be provided. At this position, the conductor foil 12 for the temperature measuring body is exposed without being covered with the coverlay, and the temperature measuring body 4 is electrically connected to the conductor foil 12 for the temperature measuring body by soldering or the like. .. The temperature measuring body 4 is electrically insulated from the connecting portion 13. The temperature measuring body 4 measures the temperature at the connecting portion 13. In this embodiment, a resistance temperature detector is used as the temperature measuring body 4. Since the resistance value when electricity is passed through the resistance temperature detector changes according to the ambient temperature (the resistance value increases as the temperature rises), the temperature is measured based on the amount of change in this resistance value. be able to. The temperature measuring body 4 is not limited to the temperature measuring resistor, and for example, a linear resistor or a thermistor may be used.

The heat equalizing plate 5 extends along the lateral direction of the flat cable 3 and is provided so as to straddle the plurality of connecting portions 13 (so as to overlap the plurality of connecting portions 13). That is, the heat soaking plate 5 is provided at a position overlapping the connecting portion 13 together with the temperature measuring body 4 described above. The heat equalizing plate 5 may be provided on the same surface as the surface provided with the connecting portion 13 (or the surface provided with the temperature measuring body 4), or may be provided on the opposite surface. The heat equalizing plate 5 is made of a material having a large thermal conductivity, and is used to equalize the temperature of the plurality of connecting portions 13. The heat soaking plate 5 is electrically insulated from the connecting portion 13 and the temperature measuring body 4. By the way, since the connecting portion 13 has low strength, it may be damaged by a temperature change. Therefore, it is preferable to use a heat soaking plate 5 having a large thermal conductivity and a small coefficient of thermal expansion. As such, in the present embodiment, Invar (also referred to as Amber) is used as the heat equalizing plate 5. Although the connection portion 13 may be damaged by an external force, the Invar is an alloy and has a relatively high mechanical strength, and the heat soaking plate 5 extends over almost the entire width of the flat cable 3. Since the flat cable 3 is reinforced, the influence of the external force on the connection portion 13 can be reduced. The heat equalizing plate 5 may be brought into direct contact with the flat cable 3, but it is preferable to interpose silicone grease or the like having a high conductivity between them.

The measuring instrument 50 is connected to a thermocouple conductor foil 11 that is connected to the thermocouple strand of the thermocouple 2. As described above, since the thermocouple 2 is formed by joining different types of thermocouple strands, there is a temperature difference (temperature gradient) in the length direction of the thermocouple 2 when the circuit is electrically closed. , A thermoelectromotive force is generated. The measuring instrument 50 of the present embodiment has a function of a voltmeter that measures the thermoelectromotive force of the thermocouple 2 via the thermocouple conductor foil 11. Further, the measuring instrument 50 is connected to the conductor foil 12 for the temperature measuring body connected to the temperature measuring body 4. As described above, in the temperature measuring body 4, the resistance value when electricity is passed changes according to the ambient temperature. The measuring instrument 50 also has a function of measuring this resistance value. Although details will be described later, the measuring instrument 50 has a function of deriving a temperature difference between the temperature sensing portion 6 and the connecting portion 13 from the voltage measured by the thermocouple conductor foil 11, and is measured by the temperature measuring body conductor foil 12. In addition to the function of deriving the temperature of the temperature measuring body 4 based on the resistance value to be measured, it also has a function of calculating the temperature of the temperature sensing unit 6 based on these temperatures and displaying it. Note that the measuring instrument 50 of the present embodiment is different from the measuring instrument 206 including the compensation circuit 205 shown in FIG. 3, and the measuring instrument 50 corresponding to the compensation circuit 205 is omitted.

When measuring the internal temperature of the semiconductor-related device using such a temperature sensor 100, the wafer 1 is installed inside the semiconductor-related device, and the temperature sensor 100 is connected to the measuring instrument 50. Since the thermocouple strands of the thermocouple 2 are two conductors of different types, a thermoelectromotive force is generated if there is a temperature difference (temperature gradient) between the temperature sensitive portion 6 and the connecting portion 13 in this state. On the other hand, since the two thermocouple conductor foils 11 to which the two thermocouple strands are connected are the same type of conductor, no thermoelectromotive force is generated. That is, since the voltage measured by the measuring instrument 50 connected to the thermocouple conductor foil 11 is the thermoelectromotive force based on the temperature difference between the temperature sensitive portion 6 and the connecting portion 13, it is felt based on the measured voltage. The temperature difference between the hot portion 6 and the connecting portion 13 can be derived. Further, since the measuring instrument 50 is also connected to the conductor foil 12 for the temperature measuring body, the resistance value when electricity is passed through the temperature measuring body 4 is measured as described above, and the temperature is measured based on the resistance value. The temperature of the connecting portion 13 provided with the body 4 can be derived. That is, the temperature of the temperature sensitive unit 6 is calculated by adding the temperature difference between the temperature sensitive unit 6 and the connection unit 13 to the temperature of the connection unit 13, and the measuring instrument 50 can display the temperature of the temperature sensitive unit 6. it can.

As described above, according to the temperature sensor 100 of the present embodiment, even when the measuring instrument 50 is installed at a place away from the semiconductor-related device, the length of the flat cable 3 is increased and the length of the expensive thermocouple 2 is increased. Since the size can be minimized, the cost can be suppressed. Further, the compensating lead wire 204 provided in the conventional temperature sensor 200 as shown in FIG. 3 is unnecessary, and the influence of the temperature tolerance of the compensating lead wire 204 is eliminated, so that the temperature of the temperature sensing unit 6 can be measured with high accuracy. Can be measured.

Next, a second embodiment of the temperature sensor according to the present invention will be described with reference to FIG. In the temperature sensor 110 of the present embodiment, the parts having the same functions as the temperature sensor 100 described above are designated by the same reference numerals in the drawings, and detailed description thereof will be omitted.

The temperature sensor 110 includes a thermocouple 2, a flat cable 3, a temperature measuring body 4, a heat equalizing plate 5, and a protective tube 14, and is used by being connected to the measuring instrument 50.

As shown in the figure, the temperature sensor 110 includes a plurality of thermocouples 2, and the temperature sensing portions 6 are arranged in a stepwise manner in the longitudinal direction. Further, the protective tube 14 uses quartz glass in the present embodiment and covers the thermocouple 2 as a whole.

According to the temperature sensor 110 configured in this way, it is possible to measure the temperature with high accuracy while suppressing the cost, similarly to the temperature sensor 100 described above. Further, since the protective tube 14 is made of quartz glass, it is possible to measure the temperature of a high temperature furnace, for example, by its heat resistance. Further, since the temperature sensing portion 6 is arranged in a stepwise position in the longitudinal direction, the temperature distribution of the high temperature furnace can be measured.

Although one embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and unless otherwise specified in the above description, the gist of the present invention described in the claims. Various modifications and changes are possible within the range of. In addition, the effects in the above embodiments merely exemplify the effects arising from the present invention, and do not mean that the effects according to the present invention are limited to the above effects.

For example, the flat cable 3 in the above embodiment may be replaced with a predetermined number of single wires (lead wires), or a rigid substrate having a predetermined conductive pattern may be used.

Further, the flat cable 3 may be replaced with a ceramic substrate having a predetermined pattern. Since the ceramic substrate has high heat resistance and can be brought close to the portion even when measuring the temperature of the portion where the temperature becomes high, the length of the thermocouple 2 can be shortened and the cost can be suppressed.

When a plurality of thermocouples 2 are provided as in the above embodiment, the heat equalizing plate 5 is arranged so as to straddle the plurality of connecting portions 13, so that even one temperature measuring body 4 can be provided. There is an advantage that the temperature of these connection portions 13 can be measured collectively, but for example, when there is only one connection portion 13, or when the connection portions 13 must be arranged apart from each other due to wiring reasons, etc. May eliminate the heat equalizing plate 5 and provide the connection portion 13 and the temperature measuring body 4 in a one-to-one relationship.

1: Wafer 2: Thermocouple 3: Flat cable (extension)
4: Temperature measuring body 5: Heat equalizing plate 6: Temperature sensitive part 7: Recessed part 8: Housing 9: Insulating film 10: Conductor foil 11: Conductor foil for thermocouple (extension body wire)
12: Conductor foil for temperature measuring body 13: Connection part 14: Protective tube 50: Measuring instrument 100, 110: Temperature sensor

Claims (4)

A thermocouple composed of different types of conductors and having a pair of thermocouple strands with the junction as the temperature sensitive part,
A pair of extension wires that are made of the same type of conductor, one end connected to the thermocouple wire on the opposite side to the side where the temperature sensitive part is located, and the other end connected to the measuring instrument. With an extension body
And a temperature measuring member provided in the direction viewed from a position overlapping toward the rear surface from the surface of the connection portion for the connection of the extension member wire and the thermocouple element,
A temperature sensor that measures the temperature at the temperature sensitive portion based on the temperature at the connection portion measured by the temperature measuring body. A plurality of the thermocouple strands and the extension strands forming a pair are provided, and a plurality of the connection portions are provided.
The temperature sensor according to claim 1, further comprising a heat equalizing plate provided across the plurality of the connecting portions. The temperature sensor according to claim 1 or 2, wherein the extension wire is formed of copper or an alloy containing copper as a main component. The extension body is a flat cable and
The flat cable includes a conductor foil for a thermocouple as an extension wire, a conductor foil for a temperature measuring body that connects the temperature measuring body and the measuring instrument, a conductor foil for the thermocouple and the temperature measuring body. The temperature sensor according to any one of claims 1 to 3, further comprising an insulating film provided with a conductor foil for use.

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