JP2002352938A - Disconnection predicting method for heater element wire of heat treatment device, and the heat-treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for predicting disconnection of a heater wire, composed of a resistance exothermic body which is the heating means installed at the surroundings of a reaction tube, in a device in which semiconductor wafers of numerous sheets are brought into the reaction tube, and heat treatment is carried out. SOLUTION: A serial process in which the wafer is brought into the reaction tube 1 and the heat treatment is carried out, and afterwards the wafer is taken out of the reaction tube 1 in a single operation; and if the time slot, in which temperature is stable before the wafer is brought into the reaction tube 1, is called steady-state temperature time, in the respective time operation, a supplied electric power to the heater wire in the steady temperature is measured. Then, based on this measurement data, the standard deviation in the steady-state temperature time in the respective time of operation is calculated, and further, based on the standard deviation for each operation, the transition of the standard deviation, for example the moving average is calculated, alarm is outputted by forecasting the disconnection of the heater element wire, when this moving average is in an increasing tendency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for predicting the breakage of a heater element in a heat treatment apparatus provided with a heater element comprising a resistance heating element provided around a reaction vessel. About.

[0002]

2. Description of the Related Art As one of semiconductor manufacturing apparatuses, a vertical heat treatment apparatus for batch processing semiconductor wafers (hereinafter, referred to as wafers) is known. This apparatus is composed of, for example, a vertical reaction tube having a lower end side serving as a carry-in / out port, a cylindrical heat insulator provided around the reaction tube, and a resistance heating element provided along the inner wall surface of the heat insulator. A plurality of wafers are held in a wafer holder in a shelf shape and loaded into the reaction tube, and the inside of the reaction tube is heated by the heater to a predetermined process temperature to remove the wafer. In this case, an oxidation process, a film formation process, or the like is performed. As the resistance heating element, for example, a heater wire such as an iron-tantalum-carbon alloy is used, and is provided in a coil shape so as to wind a reaction tube, for example.

[0003]

Among the processes performed on the above-mentioned wafer, there is a case where oxidation or annealing is performed in a high temperature atmosphere of, for example, around 1200 ° C., while the wafer is placed in a reaction tube. At the time of loading or unloading, the inside of the reaction tube is controlled to a temperature of, for example, about 500 ° C. in order to suppress the growth of a natural oxide film on the wafer surface. Therefore, the heater wire is subjected to a severe environment in which such high and low temperatures are repeated, so that, for example, a wire having a short service life is disconnected in about two years.

If the breakage of the heater wire occurs during the process, all the wafers included in the batch will be defective, resulting in a large loss cost and wasted time for the process. It is important to predict the disconnection time of the heater wire. Therefore, conventionally, the resistance value of the heater wire has been monitored, and the disconnection time has been predicted based on the transition.

However, in this method, it is difficult to accurately detect the deterioration of the heater wire because the resistance value itself is small, and cracks occur and break before the heater wire deteriorates. Therefore, there is a possibility that the heater wire may be broken during the process. In addition, such disconnections are difficult to predict and require planned maintenance.
(Maintenance) could not be performed. In some cases, the heater wires are replaced when the deterioration has progressed to some extent, but the heater wires are discarded in a state where the heater wires can still be used, resulting in high costs. I was

The present invention has been made under such circumstances, and an object of the present invention is to provide a technique capable of predicting a break in a heater wire used in a heat treatment apparatus.

[0007]

According to the method of the present invention, the electric power supplied to a heater element comprising a resistance heating element provided around a reaction vessel is controlled by a power control section based on a detected temperature value. Thus, in the method for predicting the breakage of the heater wire of an apparatus that heats the inside of the reaction vessel and heat-treats the workpiece, the power supplied to the heater wire when the temperature is stable is measured. Obtaining a standard deviation of the supply power in the time zone; and determining whether or not there is a warning before the heater wire breaks based on the transition of the standard deviation for each time zone, It is characterized by including.

More specifically, the present invention provides a step of carrying out a plurality of operations of carrying a workpiece into a reaction vessel, performing a heat treatment on the workpiece, and then carrying the workpiece out of the reaction vessel. And measuring the power supplied to the heater wire at the time of temperature stabilization for each operation, obtaining a standard deviation of the supplied power in the time zone for each operation, and a step of calculating the standard deviation of the operation for each operation. Determining, based on the transition, whether or not the heater strand is a warning before disconnection. In the present invention, the transition of the standard deviation for each operation is, for example, a moving average of the standard deviation or a time series data of the standard deviation.
This is a transition of the average value of a plurality of standard deviations divided into a plurality of segments, and it is determined that the heater wire is disconnected when the standard deviations are increasing for a predetermined period. The measurement of the power supplied to the heater wire is performed based on, for example, a control signal from a power control unit. When the temperature is stabilized, for example, it is a time period before the object to be processed is loaded into the reaction vessel. . Further, when it is determined that the heater wire is a warning before the wire breaks,
Output an alarm.

The present invention focuses on the relationship between a change in the degree of variation in the power supplied to a heater element and an abnormal change in the state of the heater element. For example, the standard deviation of the power supplied to the heater is determined for each operation and the transition is grasped, so that the disconnection of the heater wire can be predicted with high accuracy.

Further, the present invention is also realized as a heat treatment apparatus. Specifically, the object to be processed is carried into a reaction vessel, and a heater element comprising a resistance heating element provided around the reaction vessel. By controlling the electric power supplied to the power control unit based on the detected temperature value, the inside of the reaction vessel is heated to perform a heat treatment on the object to be processed, and then the operation of carrying out the object to be processed from the reaction vessel is performed. In the heat treatment apparatus, means for measuring the power supplied to the heater wire when the temperature is stable for each operation, obtaining a standard deviation of the supplied power in the time zone for each operation, and the standard for each operation. A storage unit for storing the deviation; and determination means for determining, based on the transition of the standard deviation stored in the storage unit, whether or not it is a warning before disconnection of the heater wire. To be

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a method for predicting breakage of a heater wire of a heat treatment apparatus according to the present invention is applied to a vertical heat treatment apparatus will be described below. First, the configuration of the vertical heat treatment apparatus will be briefly described with reference to FIG. This apparatus includes a vertical reaction tube 1 which is a cylindrical quartz reaction container having an open lower end. The reaction tube 1 has a gas diffusion plate 12 having a number of gas holes 11 slightly below the upper surface. The base body 2 is provided at the lower side through a heat insulator 21 on the lower side.
2 attached.

A furnace 23 which is a cylindrical heat insulator is provided around the reaction tube 1 so as to surround the reaction tube 1, and a heater 3 is provided on the inner peripheral surface of the furnace 23 with the heater 3. Is provided so as to surround the. In this example, the heater 3 is, for example, a five-stage heater 3 for dividing an area in the reaction tube 1 into a plurality of zones.
(3a to 3e). Heater 3 (3a-3)
e) is composed of a heater wire 31 which is a resistance heating element such as an iron-tantalum-carbon alloy, and is provided in a coil shape so as to wind a reaction tube, for example. The heater wires 31 may be provided in a corrugated shape, for example, along the inner peripheral surface of the furnace body 23 instead of being provided in a coil shape.

A gas supply pipe 24 and an exhaust pipe 25 extend through the heat insulator 21 below the reaction tube 1, and the gas supply pipe 24 is vertically raised so as to be in contact with the upper surface of the reaction tube 1 and gas diffusion. The exhaust pipe 25 is connected to a lower portion of the reaction tube 1 while being inserted into the space between the plate 12. An opening at the lower end of the reaction tube 1 is airtightly closed by a lid 14 provided on a boat elevator 13, and a large number of wafers to be processed are placed on the lid 14. Wafer boat holding W in a shelf shape
15 is mounted via a heat retaining cylinder 16. Next, the power control system of the heater 3 will be described. Each of the divided heaters 3 (3a to 3e) has a power supply unit 4 (4a).
To 4e) are connected and the respective power supply units 4 (4a to 4e) are connected.
e) is connected to the power control unit 5 (5a to 5e). Further, thermocouples 30 (30a to 30e), which are temperature detectors, are provided at corresponding positions in the furnace body 23 to detect the temperatures of the heaters 3 (3a to 3e). The power control unit 5 (5a to 5e) outputs a control signal to the power supply unit 4 (4a to 4e) based on the detected temperature value and the set temperature value of the corresponding thermocouple 30 (30a to 30e). It is configured. More specifically, although not shown, a thermocouple is also provided in the reaction tube 1, and detection signals from thermocouples inside and outside the reaction tube 1 are selected according to timing and combined as a temperature detection value. I have.

FIG. 2 is a diagram showing a control system for one stage of the heater 3. As shown in FIG.
1 is supplied to the heater 3 by controlling the voltage from the switching element 42, and the power control unit 5 amplifies the deviation between the detected temperature value and the set temperature value to turn on the switching element 42. It is configured to output a control signal for controlling the angle. Therefore, this control signal is transmitted to the power supply unit 4
Corresponds to the electric power supplied to the heater 3.

Further, the control system includes a disconnection predicting unit 6 for predicting a disconnection of the heater wire 31. The disconnection predicting unit 6 includes a storage unit 61, a data processing unit 62, and a judgment unit. 6
3 is provided. The data processing section 62 has a function of monitoring the control signal from the power control section 5 to measure the power supplied to the heater element wire 31 and storing the measurement result in the storage section 61.

Here, the wafer boat 15 is loaded into the reaction tube 1 to perform a heat treatment, and then a series of steps of unloading the wafer boat 15 from the reaction tube 1 is performed once, and the wafer boat 15 is reacted. A time period in which the temperature is stable before being carried into the pipe 1 is called a steady temperature time.
The data processing unit 62 obtains a standard deviation at a steady temperature in each operation based on the data of the supplied power at a steady temperature in each operation stored in the storage unit 61 and stores the standard deviation in the storage unit 61. The storage unit 61 has a function of storing and further calculating a transition of the standard deviation, for example, a moving average, based on the standard deviation for each operation and storing it in the storage unit 61. Also, the judgment means 63
Has a function of determining whether or not it is a warning of disconnection of the heater wire 31 based on the moving average of the standard deviation stored in the storage unit 61. In FIG. 2, reference numeral 64 denotes an alarm which comprises an alarm lamp or a means for displaying an alarm on a screen.
An alarm generating unit that generates an alarm when the predicting unit 63 predicts that the heater element wire 31 will be disconnected. Although the disconnection predicting unit 6 is functionally represented in FIG. 2, it is actually composed of, for example, a CPU, a ROM and a RAM storing a data processing program, and each stage has a head.
Power controllers 5 (5a to 5e) corresponding to
5b), the heaters 3 (3a to 3a) of each stage are fetched.
Data is processed every 3e).

Next, the operation of the above embodiment will be described. First, a large number of wafers to be processed are mounted on a wafer boat 15 located below the reaction tube 1 in a shelf shape.
The elevator 13 is raised, and the wafer boat 15 (wafer W) is carried into the reaction tube 1. Thereafter, the power supplied to the heater 3 (heater wire 31) is increased to raise the temperature inside the reaction tube 1 to a predetermined heat treatment temperature (process temperature). While supplying a suitable chlorine gas into the reaction tube 1, the gas is exhausted through the exhaust pipe 25 to oxidize (heat-treat), for example, a silicon layer on the wafer W. Next, the temperature inside the reaction tube 1 is lowered, and then the boat elevator 13 is lowered to carry out the wafer boat 15.
Temperature and heat corresponding to one zone in the reaction tube 1 when the number of operations (loading, heat treatment, and unloading of the wafer W) has been performed.
FIG. 3 shows an example of the power supplied to the element wire 31. In FIG. 3, (1) shows the set temperature, (2) shows the supplied power, respectively.
The data (2) indicating the temporal change of the supplied power is data obtained by monitoring the control signal from the power control unit 5 as described above, and is stored in the storage unit 61. Reaction tube 1
Is about 750 ° C. before and during the loading of the wafer W, and from about 750 ° C. to about 1130 ° C. which is the process temperature at a predetermined heating rate in the heating step after the loading of the wafer W, for example. In the heat treatment step, the temperature is raised and maintained at the process temperature for a predetermined time, and in the temperature lowering step, the temperature is lowered to around 750 ° C. at a predetermined temperature decreasing rate. Further, the power supplied to the heater wire 31 increases in accordance with the set temperature,
Although it decreases, it changes as (2) according to the control coefficient of the power control unit 5 and the like.

Assuming that the operation is performed once, at a steady temperature (when the temperature in the reaction tube 1 is stabilized before the wafer W is loaded).
Data processing unit 6 based on the power supply data at
The standard deviation of the power supply at the time of steady temperature is obtained by 2 and stored in the storage unit 61. In practice, the wafer W placed on the wafer boat 15 before processing is at room temperature, and when it is loaded into the reaction tube 1, the temperature in the reaction tube 1 is slightly disturbed. The data section for this is a point in time before the wafer boat 15 carries out the loading operation. Operations such as loading, heat treatment, and unloading of the wafer W are repeatedly performed, and time-series data of power supplied to the heater wires 31 is stored in the storage unit for each operation, and the data processing unit 62 The standard deviation of the supplied power at the time of the steady temperature for each operation is calculated based on the standard deviation and stored in the storage unit 62. The solid line in FIG. 4 indicates 11 at the steady temperature for each operation in one zone.
This is the standard deviation of the supplied power in 00 seconds. Further, the data processing unit 62 obtains a transition of the standard deviation, for example, a 20-section moving average based on the time series data of the standard deviation, and stores it in the storage unit 62. The dotted line in FIG. 4 shows a 20-section moving average obtained by averaging 20 consecutive points of the standard deviation at each operation shown by the solid line.

As can be seen from the dotted line in FIG.
The moving average has a tendency to continuously increase from a little after 0 times, and then the heater element 31
Is disconnected. In FIG. 4, a section where the moving average is continuously increasing is represented by T. When the heater wire 31 is disconnected in this manner, the transition of the standard deviation is continuously increasing as a prelude to that fact, and the judging means 63 grasps this increasing tendency from the data in the storage section 61 and determines the heater wire. It is determined that the disconnection will occur soon, and a signal is sent to the alarm generator 64 to generate an alarm. As a result, the operator stops the operation of the apparatus at that time and replaces the heater element wire 31, for example.

According to the above-described embodiment, the power supplied to the heater wire 31 when the temperature is stable is measured for each operation, and the fact that the standard deviation for each operation is increasing is determined by a moving average. Since it is grasped and the heater wire 31 is predicted to be disconnected, the disconnection of the heater wire 31 can be predicted with high accuracy, and the heater wire 31 is disconnected during the process. It is possible to prevent the processing body from becoming defective, and it is also possible to prevent the heater wires 31 from being replaced and the cost being increased even though they can be used sufficiently.
Regarding the relationship between the standard deviation of the power supplied to the heater element 31 and the disconnection, the standard deviation is an index of the degree of the fluctuation of the power supplied to the heater element 31, so that the degree of the fluctuation increases. When there is a tendency, it is considered that an abnormal change has started to occur in the state of the heater wire 31 and it is a warning of the disconnection.

In the above embodiment, the moving average of the standard deviation is obtained. However, in the present invention, the time series data of the standard deviation shown by the solid line in FIG. Of the heater element wires 31 based on the transition of the average value of the divided standard deviations.
It may be determined whether or not it is a warning of the disconnection. FIG. 5 shows the transition of the average value of the divided three standard deviations by dividing the time series data of the standard deviation into three, and it can be seen that there is a continuous increasing tendency in the section T. .

[0022]

According to the present invention, the power supply to the heater wire at the time of stable temperature is measured for each operation and the transition of the standard deviation for each operation is grasped. -It is possible to predict the disconnection of the heater wire with high accuracy, and to prevent the object to be processed from becoming defective due to the disconnection of the heater wire during the process. This makes it possible to perform planned maintenance on the heat treatment apparatus.

[Brief description of the drawings]

FIG. 1 is a vertical side view showing a vertical heat treatment apparatus to which the method of the present invention is applied.

FIG. 2 is an explanatory diagram showing a power control system for a heater element wire and a portion for predicting a disconnection in the vertical heat treatment apparatus.

FIG. 3 is a characteristic diagram showing a temperature set value and power supplied to a heater element wire in one operation in association with each other.

FIG. 4 is a graph showing the transition of the standard deviation of the power supplied to the heater wires when the temperature is stabilized before the wafer is loaded, which is obtained for each operation, and which is simply expressed in a time series of the standard deviation, and FIG. 9 is a characteristic diagram showing data corresponding to an average in association with each other.

FIG. 5 divides a plurality of time-series data of the standard deviation of the power supplied to the heater wires when the temperature is stabilized before the loading of the wafer and obtains the standard deviation of a plurality of divided standard deviations. It is a characteristic diagram which shows transition of an average value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tube 13 Boat elevator 14 Cover 15 Wafer boat W Semiconductor wafer 23 Furnace 24 Gas supply pipe 25 Exhaust pipe 3 (3a-3e) Heater 30 (30a-30e) Thermocouple 4 (4a-4) 4e) Power supply unit 5 (5a to 5e) Power control unit 6 Disconnection prediction unit 61 Storage unit 62 Data processing unit 63 Judging means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F27D 21/00 F27D 21/00 G // H01L 21/22 511 H01L 21/22 511A 21/31 21/31 EF term (reference) 3K058 AA42 AA82 BA19 CA05 CA12 CA23 CA32 4K056 AA09 BA01 BB06 CA18 FA04 FA13 FA27 4K061 AA01 AA05 BA11 CA03 DA05 FA07 GA01 5F045 AA20 AB32 AC11 DP19 EK06 EK22 EM10 EN05

Claims (15)

[Claims] An electric power control section controls the power supplied to a heater element comprising a resistance heating element provided around a reaction vessel by a power control section based on a detected temperature value to heat the inside of the reaction vessel. Of a device that performs heat treatment on the workpiece
In the method of predicting the disconnection of the heater wire, the power supply to the heater wire when the temperature is stable is measured,
Determining a standard deviation of the supplied power in the time zone; and determining whether or not there is a warning before disconnection of the heater wire based on a transition of the standard deviation for each time zone. A method for predicting breakage of a heater wire in a heat treatment apparatus, the method comprising: 2. A reaction control unit controls the power supplied to a heater wire comprising a resistance heating element provided around a reaction vessel by a power control unit based on a detected temperature value to heat the inside of the reaction vessel. Of a device that performs heat treatment on the workpiece
In the method for predicting the disconnection of a strand, a step of carrying out a plurality of operations of carrying the object to be processed into the reaction vessel, carrying out the heat treatment on the object to be processed, and then carrying the object out of the reaction vessel. Measuring the power supplied to the heater wire at the time of temperature stabilization for each operation, and obtaining a standard deviation of the supplied power in the time zone for each operation; and a transition of the standard deviation for each operation. Determining whether or not there is a warning before disconnection of the heater element wire based on the above method. 3. The method according to claim 1, wherein the transition of the standard deviation is a moving average of the standard deviation. 4. The transition of the standard deviation is a transition of an average value of a plurality of standard deviations divided into a plurality of time series data of the standard deviation. Of predicting breakage of a heater wire in the heat treatment apparatus of FIG. 5. The heat treatment apparatus according to claim 1, wherein when the standard deviation has an increasing tendency for a predetermined period, it is determined that there is a warning before the heater wire breaks. A method for predicting disconnection of a heater wire. 6. The heat treatment apparatus according to claim 1, wherein the power supply to the heater wire is measured based on a control signal from a power control unit. -A method for predicting wire breakage. 7. The method according to claim 1, wherein when the temperature is stable, the object to be processed is not loaded into the reaction vessel. 8. The heat treatment device according to claim 1, wherein an alarm is output after it is determined that the heater wire is a warning before disconnection. Disconnection prediction method. 9. An object to be processed is carried into a reaction vessel, and power supplied to a heater element comprising a resistance heating element provided around the reaction vessel is controlled by a power control section based on a detected temperature value. In the heat treatment apparatus, which heats the inside of the reaction vessel and heat-treats the object to be processed, and then carries out the operation of unloading the object from the reaction vessel, supply to the heater wires when the temperature is stable Means for measuring power for each operation, obtaining a standard deviation of the supplied power in the time zone for each operation, a storage unit for storing the standard deviation for each operation, and a standard stored in the storage unit. A heat treatment apparatus comprising: a determination unit configured to determine, based on a change in the deviation, whether or not the heater wire is a warning before disconnection. 10. A means for calculating a moving average of the standard deviation based on the standard deviation stored in the storage unit, wherein the determining means determines a moving average of the standard deviation based on the moving average of the standard deviation.
The heat treatment apparatus according to claim 9, wherein it is determined whether or not there is a warning before the wire breaks. And means for dividing a plurality of time series data of the standard deviation based on the standard deviation stored in the storage unit and calculating a transition of an average value of the divided standard deviations, The heat treatment apparatus according to claim 9, wherein the judging means judges whether or not it is a warning before the heater wire breaks based on the average value. 12. The heat treatment apparatus according to claim 9, further comprising means for outputting an alarm when it is determined that the heater wire is a warning before the disconnection. 13. The heat treatment apparatus according to claim 9, wherein said judging means judges that the heater wire is disconnected when said standard deviation has been increasing for a predetermined period. . 14. The heat treatment apparatus according to claim 9, wherein the measurement of the power supplied to the heater wire is performed based on a control signal from a power control unit. 15. The heat treatment apparatus according to claim 9, wherein when the temperature is stable, the object is not loaded into the reaction vessel.