WO2016127490A1 - Fault diagnosis and treatment method and system for thermocouples in heat treatment apparatus - Google Patents

Fault diagnosis and treatment method and system for thermocouples in heat treatment apparatus Download PDF

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Publication number
WO2016127490A1
WO2016127490A1 PCT/CN2015/076715 CN2015076715W WO2016127490A1 WO 2016127490 A1 WO2016127490 A1 WO 2016127490A1 CN 2015076715 W CN2015076715 W CN 2015076715W WO 2016127490 A1 WO2016127490 A1 WO 2016127490A1
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Prior art keywords
temperature
thermocouple
temperature control
control zone
sampling
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PCT/CN2015/076715
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French (fr)
Inventor
Dong Xu
Ai WANG
Feng Wang
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Beijing Sevenstar Electronic Co., Ltd.
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Application filed by Beijing Sevenstar Electronic Co., Ltd. filed Critical Beijing Sevenstar Electronic Co., Ltd.
Priority to KR1020177024580A priority Critical patent/KR101929559B1/en
Publication of WO2016127490A1 publication Critical patent/WO2016127490A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
    • G01K7/026—Arrangements for signalling failure or disconnection of thermocouples
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/22—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element being a thermocouple

Definitions

  • the present invention generally relates to the field of integrated circuit manufacturing, more particularly, to a fault diagnosis and treatment method and system for thermocouples used in a heat treatment apparatus.
  • heat treatment apparatus plays an important role in wafer manufacturing processes including diffusion, annealing, alloying, oxidation, and film formation, etc., and performs accurate temperature control to the wafer surfaces.
  • thermocouple has the features of high measuring precision, wide measuring range, small size, fast response, and long service life, and is widely applied in the heat treatment apparatus.
  • thermocouple As shown in Fig. 1 which illustrates three different states of the thermocouple including normal state, short-circuit fault state and open-circuit fault state.
  • a temperature sensing module of the temperature control system having open-circuit alarm function will output an alarm signal to a logic controller and thus the open-circuit fault can be detected easily.
  • thermocouple While when the thermocouple is in the short-circuit fault state, since the temperature data collected by the thermocouple changes with the location of the short-circuit point, and the short-circuit fault varies with the actual environment in which the thermocouple is involved, it is difficult to determine the short-circuit fault of the thermocouple.
  • an object of the present invention is to provide a fault diagnosis and treatment method for thermocouples used in a heat treatment apparatus which enables correct diagnosis on whether the thermocouples are in the short-circuit fault state and provides information to a temperature controller accordingly, so that the temperature controller can take correct and promptly measures to meet the process requirement and reduce the loss of equipment and product.
  • the present invention provides a fault diagnosis and treatment method for thermocouples in a heat treatment apparatus.
  • the heat treatment apparatus includes multiple temperature control zones each having a thermocouple group and a corresponding heating unit.
  • the method comprises:
  • step S1 performing thermocouple fault diagnosis according to a sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group; if the diagnosis result is normal, turning to step S2;otherwise, turning to step S5;
  • step S2 performing thermocouple fault diagnosis according to a sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone obtained by the corresponding thermocouple groups; if the diagnosis result is normal, turning to step S3; otherwise, turning to step S5;
  • thermocouple fault diagnosis according to a change in sampling temperature in each temperature control zone obtained by the corresponding thermocouple group while changing the power control of each corresponding heating unit; if the diagnosis result is normal, turning to step S4; otherwise, turning to step S5;
  • step S4 performing thermocouple fault diagnosis according to changes in sampling temperature in each temperature control zone and its adjacent temperature control zone/zones obtained by the corresponding thermocouple groups while changing the power control of the heating units in each temperature control zone and its adjacent temperature control zone/zones, if the diagnosis result is normal, turning to step S1; otherwise, turning to step S5;
  • step S5 outputting a short-circuit alarming signal and performing corresponding compensation treatment.
  • the step S1 comprises:
  • step S11 sampling the temperatures of each temperature control zone by the corresponding thermocouple group; calculating the sampling temperature variation in a sampling period of each temperature control zone according to the sampling temperatures of the temperature control zone;
  • step S12 during a normal temperature ramp upramp up period in a heat treatment process, determining whether the sampling temperature variation is greater than a first threshold value, and/or, during a normal temperature ramp downramp down period in the heat treatment process, determining whether the sampling temperature variation is less than a second threshold value; wherein, the first threshold value is a maximum temperature ramp upramp up value corresponding to the temperature control zone during the sampling period, the second threshold value is a negative value of a maximum temperature ramp downramp down value corresponding to the temperature control zone during the sampling period;
  • step S13 if yes, adding one to a first count value which represents short-circuit fault state
  • step S14 repeating step S12 and step S13, if the first count value is greater than a preset value, outputting the short-circuit alarming signal.
  • the step S2 comprises:
  • step S21 sampling the temperatures of each temperature control zone by the corresponding thermocouple group; and calculating the temperature difference variation between each temperature control zone and its adjacent temperature control zone according to the sampling temperatures obtained by the corresponding thermocouples;
  • step S22 during a normal temperature ramp up period in the heat treatment process, determining whether the temperature difference variation is greater than a third threshold value, and/or, during a normal temperature ramp down period in the heat treatment process, determining whether the temperature difference variation is e less than a fourth threshold value; wherein, the third threshold value is a maximum temperature ramp up difference between each temperature control zone and its adjacent temperature control zone, the fourth threshold value is a negative value of a maximum temperature ramp down difference between each temperature control zone and its adjacent temperature control zone;
  • step S23 if yes, adding one to a second count value which represents short-circuit fault state
  • step S22 repeating the step S22 and the step S23, if the second count value is greater than a preset value, outputting the short-circuit alarming signal.
  • the step S3 comprises:
  • step S31 calculating the power control variation during a control period to each heating unit according to the power outputs to the heating unit;
  • step S32 accumulating the sampling temperature variation of each temperature control zone by number of sampling time-delay cycles to obtain an accumulated sampling temperature variation of each temperature control zone; accumulating the power control variation by the number of the sampling time-delay cycles to obtain an accumulated power control variation to each heating unit; calculating an accumulated standard temperature variation of each temperature control zone corresponding to the accumulated power control variation to each heating unit according to a maximum temperature-ramp up power control rate, a maximum temperature-ramp down power control rate, a maximum temperature ramp up rate, and a maximum temperature ramp down rate of the temperature control zone by using a linear interpolation method; determining whether the absolute value of the accumulated sampling temperature variation is greater than ⁇ -times the absolute value of the accumulated standard temperature variation of the same temperature control zone, wherein ⁇ is a system constant, the number of the sampling time-delay cycle is set according to thermocouple type, heating system time-delay constant and sampling system time-delay constant;
  • step S33 if yes, adding one to a third count value which represents short-circuit fault state
  • step S34 repeating the step S32 and the step S33, if the third count value is greater than a preset value, outputting the short-circuit alarming signal.
  • the ⁇ is between 1 and 2.
  • the step S4 comprises:
  • step S41 calculating the power control variations during a control period to each heating unit
  • step S42 accumulating the sampling temperature variations of each temperature control zone and its adjacent temperature control zone/zones by number of sampling time-delay cycles to obtain accumulated sampling temperature variations of each temperature control zone and its adjacent temperature control zone/zones; accumulating each of the power control variations by the number of the sampling time-delay cycles to obtain an accumulated power control variation of each temperature control zone; calculating accumulated standard temperature variations of each temperature control zone and its adjacent temperature control zone/zones corresponding to the accumulated power control variations to the corresponding heating units according to a maximum temperature-ramp up power control rate, a maximum temperature-ramp down power control rate, a maximum temperature ramp up rate, and a maximum temperature ramp down rate by using a linear interpolation method; determining whether the absolute value of the accumulated sampling temperature variation of each temperature control zone is greater than ⁇ -times the absolute value of the sum of the accumulated standard temperature variations of each temperature control zone and its adjacent temperature control zone/zones, wherein ⁇ is a system constant, the number of the sampling time-delay cycle is set according
  • step S43 if yes, adding one to a fourth count value which represents short-circuit fault state
  • step S44 repeating the step S42 and the step S43, if the fourth count value is greater than a preset value, outputting the short-circuit alarming signal.
  • the ⁇ is between 0 and 1.
  • each thermocouple group comprises an inner thermocouple disposed within a processing tube of the heat treatment apparatus, a first outer thermocouple and a second outer thermocouple disposed outside the processing tube close to the corresponding heating unit, and an overtemperature thermocouple disposed close to the first and second outer thermocouples;
  • the step 5 comprises: switching temperature control mode from inner thermocouple-based mode to first outer thermocouple-based mode, or from first outer thermocouple-based mode to second outer thermocouple-based mode, or from second outer thermocouple-based mode to overtemperature thermocouple-based mode in turn, and continuing the process.
  • the present invention also provides a system using the fault diagnosis and treatment method mentioned above.
  • the heat treatment apparatus includes multiple temperature control zones each having a thermocouple group and a heating unit.
  • the system comprises a filter, a temperature sensing module, a logical processor, a temperature controller and a power controller which form a control loop; the temperatures sampled by each of the thermocouple groups are processed by the filter, the temperature sensing module and the logical processor, wherein the logical processor determines the current working state of each thermocouple according to the sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group, the sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone obtained by the corresponding thermocouple groups, the sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple groups and the power control variation to each heating unit, and the sampling temperature variations of each temperature control zone and its adjacent temperature control zone/zones and the power control variations to the corresponding heating units in each temperature control zone and its adjacent temperature control zone/zones; and provides diagnosis result to the temperature
  • each thermocouple group comprises an inner thermocouple disposed within a processing tube of the heat treatment apparatus, a first outer thermocouple and a second outer thermocouple disposed outside the processing tube close to the corresponding heating unit, and an overtemperature thermocouple disposed close to the first and second outer thermocouples
  • the corresponding compensation treatment comprises: switching temperature control mode from inner thermocouple-based mode to first outer thermocouple-based mode, or from first outer thermocouple-based mode to second outer thermocouple-based mode, or from second outer thermocouple-based mode to overtemperature thermocouple-based mode in turn, and continuing the process.
  • thermocouple short-circuit fault can be diagnosed by real-time monitoring the sampling temperature variation obtained by each thermocouple group, the sampling temperature difference variation obtained by each thermocouple group and another thermocouple group in an adjacent temperature control zone, change in sampling temperature obtained by each thermocouple group while changing the power control of the corresponding heating unit, and changes in sampling temperature obtained by each thermocouple group and another thermocouple group (s) in adjacent temperature zone (s) while changing the power controls of the corresponding heating units.
  • the diagnosis result can be sent to the temperature controller to take correct and promptly measures according to the processing requirement, thereby reducing the loss of equipment and product.
  • Fig. 1 illustrates the three states of a thermocouple used in a heat treatment apparatus including normal state, short-circuit state and open-circuit state;
  • Fig. 2 is a schematic diagram showing five temperature control zones and five heating units in the heat treatment apparatus
  • Fig. 3 is a block chart showing the power control system utilizing the thermocouple fault diagnosis and treatment method of the present invention
  • thermocouple fault diagnosis and treatment method according to an embodiment of the present invention
  • Fig. 5 illustrates the maximum temperature differences in temperature control zone_i and temperature control zone_i+1;
  • Fig. 6 illustrates the maximum temperature differences in temperature control zone_n and temperature control zone_n-1;
  • Fig. 7 illustrates the maximum temperature differences in temperature control zone_i+j and temperature control zone_i+j+1 (i+j+1 ⁇ n) ;
  • Fig. 8 illustrates thermocouple fault diagnosis steps according to the sampling temperature variation obtained by each thermocouple group
  • Fig. 9 illustrates thermocouple fault diagnosis steps according to the sampling temperature difference variation obtained by each thermocouple group and another thermocouple group in an adjacent temperature control zone;
  • Fig. 10 illustrates thermocouple fault diagnosis steps according to the sampling temperature variation obtained by each thermocouple group and the power control variation to the heating unit corresponding to the thermocouple group;
  • Fig. 11 illustrates thermocouple fault diagnosis steps according to the sampling temperature variations obtained by each thermocouple group and another thermocouple groups in adjacent temperature control zones and the power control variations to the heating units in the temperature control zone corresponding to the thermocouple group and its adjacent temperature control zones.
  • the present invention aims to determine the working state of the thermocouple based on the sampling temperature and take corresponding measures when the thermocouple is determined to be in the short-circuit fault state, thereby preventing the decrease of the process effect; furthermore, the heat treatment processing can be ensured proceeding through compensation treatment such as using different thermocouples and switching the temperature control mode correspondingly, which minimize the losses.
  • the heat treatment apparatus can be divided into multiple temperature control zones as required.
  • each temperature control zone multiple thermocouples and a heating unit can be provided, and the multiple thermocouples can be of different types.
  • Fig. 2 is a schematic diagram showing five temperature control zones and the corresponding five heating units.
  • the heat treatment apparatus has five temperature control zones (zone1, zone2, zone3, zone 4, and zone 5) each comprising a thermocouple group and a heating unit.
  • Each thermocouple group comprises four thermocouples, that is, an inner thermocouple (Inner TC) which is disposed within a processing tube of the heat treatment apparatus, a first outer thermocouple (OuterA TC) and a second outer thermocouple (OuterB TC) disposed outside the processing tube close to the corresponding heating unit, and an overtemperature thermocouple (OverTemp TC) disposed close to the first and second outer thermocouples.
  • Inner TC inner thermocouple
  • OuterA TC first outer thermocouple
  • OuterB TC second outer thermocouple
  • OverTemp TC overtemperature thermocouple
  • Fig. 3 is a block chart showing the power control system utilizing the thermocouple fault diagnosis and treatment method of the present invention. As shown in Fig. 3, the system also comprises a filter, a temperature sensing module, a logical processor, a temperature controller and a power controller which form a control loop.
  • thermocouples 1 ⁇ 5 in Fig. 3 The temperatures sampled by the five thermocouple groups (thermocouples 1 ⁇ 5 in Fig. 3) are processed by the filter, the temperature sensing module and the logical processor.
  • the logical processor determines the working state of the thermocouples according to a sampling temperature variation obtained by each thermocouple group during a sampling period, a sampling temperature difference variation obtained by each thermocouple group and another thermocouple group in an adjacent temperature control zone, the sampling temperature variation obtained by each thermocouple group and power control variation to the heating unit corresponding to the thermocouple group during a control period, and the sampling temperature variations obtained by each thermocouple group and another thermocouple group (s) in the adjacent temperature control zone (s) and the power control variations to the corresponding heating units during the control period, and then provides the diagnosis result to the temperature controller and the power controller to perform corresponding compensation treatment.
  • each sampling temperature variation ⁇ T (unit °C) in a sampling period ⁇ t (unit second) obtained by the thermocouple group should be equal to or less than a first threshold value TH1.
  • each sampling temperature variation ⁇ T (unit °C) in the sampling period ⁇ t (unit second) obtained by the thermocouple group should be equal to or greater than a second threshold value TH2.
  • the RampUP Ratemax represents the measured temperature variation per minute in the temperature control zone (T Min (i+1) -T Min (i) ) when full power is outputted to the corresponding heating unit in the temperature control zone, the measured value varies with the temperature range and the working time of the heating unit.
  • the sampling time should be selected and the sampling period should be calibrated.
  • the RampDown Ratemax represents the measured temperature variation per minute in the temperature control zone (T Min (i+1) -T Min (i) ) when no power is outputted to the corresponding heating unit in the temperature control zone, the measured value varies with the temperature range and the working time of the heating unit.
  • the sampling time should be selected and the sampling period should be calibrated.
  • the maximum temperature ramp up difference ⁇ T NearMaxUp in two adjacent temperature control zones represents the temperature difference between the temperatures sampled in two adjacent temperature control zones (adjacent temperature control zone and current temperature control zone) , wherein full power is outputted to the heating unit in the current temperature control zone and no power is outputted to the heating unit in the adjacent temperature control zone.
  • the temperature difference varies with the temperature range and the working time of the heating units. The sampling time should be selected and the sampling period should be calibrated.
  • the maximum temperature ramp down difference ⁇ T NearMaxDown in two adjacent temperature control zones is the temperature difference between the temperatures in two adjacent temperature control zones (adjacent temperature control zone and current temperature control zone) , wherein no power is outputted to the heating unit in the current temperature control zones and full power is outputted to the heating unit in the adjacent temperature control zone.
  • the temperature difference varies with the temperature range and the working time of the heating units. The sampling time should be selected and the sampling period should be calibrated.
  • each kind of temperature difference includes a positive variation value and a negative variation value.
  • thermocouple fault diagnosis and treatment method will be described in further details with reference to Fig. 4. As shown in Fig. 4, the method comprises the following steps:
  • step S1 performing thermocouple fault diagnosis according to a sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group; if the diagnosis result is normal, turning to step S2; otherwise, turning to step S5;
  • step S2 performing thermocouple fault diagnosis according to a sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone obtained by the corresponding thermocouple groups; if the diagnosis result is normal, turning to step S3; otherwise, turning to step S5;
  • step S3 performing thermocouple fault diagnosis according to a change in sampling temperature in each temperature control zone obtained by the corresponding thermocouple group while changing the power control of each corresponding heating unit; if the diagnosis result is normal, turning to step S4; otherwise, turning to step S5;
  • step S4 performing thermocouple fault diagnosis according to changes in sampling temperature in each temperature control zone and its adjacent temperature control zone/zones obtained by the corresponding thermocouple groups while changing the power controls of the heating units in each temperature control zone and its adjacent temperature control zone/zones, if the diagnosis result is normal, turning to step S1; otherwise, turning to step S5;
  • the temperature control mode can be switched from Inner TC-based mode to OuterA TC-based mode, or from OuterA TC-based mode to OuterB TC-based mode, or from OuterB TC-based mode to OverTemp TC based mode in turn, so as to continue the process.
  • step S1 further comprises:
  • step S13 if yes, that is, if ⁇ T> TH1 or ⁇ T ⁇ TH2, adding one to the first count value iCount1; otherwise, if TH2 ⁇ T ⁇ TH1, keeping the first count value iCount1 the same;
  • step S14 repeating step S12 and step S13, if the first count value iCount1 is greater than a preset value, outputting the short-circuit alarming signal.
  • step S2 if the diagnosis result obtained from step S1 is normal, step S2 can be performed for further diagnosis.
  • step S2 further comprises:
  • step S22 during the normal temperature ramp up period in the heat treatment process, determining whether the sampling temperature difference variation is greater than a third threshold value TH3, and/or, during the normal temperature ramp down period, determining whether the sampling temperature difference variation is less than a fourth threshold value TH4; wherein, the third threshold value TH3 is the maximum temperature ramp up difference of two adjacent temperature control zones ⁇ T NearMaxUp , the fourth threshold value TH4 is a negative value of the maximum temperature ramp down difference of two adjacent temperature control zones T NearMaxDown ;
  • step S24 repeating step s22 and step s23, if the second count value iCount2 is greater than a preset value, outputting the short-circuit alarming signal.
  • step S3 if the diagnosis result obtained from step S2 is normal, step S3 can be performed for further diagnosis.
  • Fig. 10 which illustrates the thermocouple fault diagnosis steps according to the temperature variation obtained by each thermocouple group and the power control variation to the heating unit corresponding to the thermocouple, step S3 further comprises:
  • the power control variation ⁇ CtrlOut Zone (i) during the control period ⁇ t1 will lead to a corresponding temperature variation ⁇ T ⁇ CtrlOut , and the temperature variation caused by the power control variation can be calculated by a linear interpolation method.
  • step S32 accumulating the sampling temperature variation ⁇ T of the i th temperature control zone obtained by the corresponding thermocouple group by number of sampling time-delay cycles N Cycle to obtain an accumulated sampling temperature variation of the i th temperature control zone; accumulating the power control variation CtrlOut Zone (i) by the number of the sampling time-delay cycles N Cycle to obtain an accumulated power control variation to the heating unit in the i th temperature control zone; calculating an accumulated standard temperature variation ⁇ T Standard (i) corresponding to the accumulated temperature control variation according to a maximum temperature-ramp up control rate CtrlRampUpRate max , a maximum temperature-ramp down control rate CtrlRampDownRate max , a maximum temperature ramp up rate RampUpRate max , and a maximum temperature ramp down rate RampDownRate max of the i th temperature control zone by using the linear interpolation method; determining whether the absolute value of the accumulated sampling temperature variation is greater than ⁇ -times the absolute value
  • step S33 if yes, that is, if adding one to the third count value iCount3; otherwise, keeping the third count value iCount3 the same;
  • step S34 repeating step s32 and step s33, if the third count value iCount3 is greater than a preset value, outputting the short-circuit alarming signal.
  • step S4 can be performed for further diagnosis.
  • Fig. 11 which illustrates the thermocouple fault diagnosis steps according to the temperature variations obtained by each thermocouple group and another thermocouple group (s) in the adjacent temperature control zone (s) and the power control variations to the corresponding heating units, step S4 further comprises:
  • ⁇ CtrlOut Zone (i-1) CtrlOut Zone (i-1) t+ ⁇ t1 -CtrlOut Zone (i-1) t ;
  • ⁇ CtrlOut Zone (i+1) CtrlOut Zone (i+1) t+ ⁇ t1 -CtrlOut Zone (i+1) t ;
  • the power control variation ⁇ CtrlOut Zone (i) / ⁇ CtrlOut Zone (i-1) / ⁇ CtrlOut Zone (i+1) during the control period ⁇ t1 will lead to a corresponding temperature variation ⁇ T ⁇ CtrlOut , and the temperature variation caused by the power control variation can be calculated by a linear interpolation method;
  • step S42 accumulating the sampling temperature variation ⁇ T of each of the three temperature control zones obtained by the corresponding thermocouple groups by number of sampling time-delay cycles N Cycle to obtain an accumulated sampling temperature variation of each of the temperature control zones; accumulating each of the power control variations CtrlOut Zone (i) , ⁇ CtrlOut Zone (i-1) , ⁇ CtrlOut Zone (i+1) by the number of the sampling time-delay cycles N Cycle to obtain the accumulated power control variations calculating the accumulated standard temperature variations ⁇ T Standard (i) , ⁇ T Standard (i-1) , ⁇ T Standard (i+1) corresponding to the accumulated power control variations according to the maximum temperature-ramp up control rate CtrlRampUpRate max , the maximum temperature-ramp down control rate CtrlRampDownRate max , the maximum temperature ramp up value RampUpRate max , and the maximum temperature ramp down value RampDownRate max of each of the three temperature control zones by using the linear inter
  • step S43 if yes, adding one to the fourth count value iCount4; otherwise, keeping the fourth count value iCount4 the same;
  • step S44 repeating step s42 and step s43, if the fourth count value iCount4 is greater than a preset value, outputting the short-circuit alarming signal.
  • thermocouple in the thermocouple group When the logical controller determines that a thermocouple in the thermocouple group is in the short-circuit fault state, it sends the alarming signal to the temperature controller to use other thermocouples (Inner TC ⁇ OuterA TC ⁇ OuterB TC ⁇ OverTemp TC) and switch temperature controlling method (Cascade ⁇ Spike ⁇ OverTemp) , so as to ensure the proceeding of the heat treatment process.
  • thermocouples Inner TC ⁇ OuterA TC ⁇ OuterB TC ⁇ OverTemp TC
  • switch temperature controlling method Cascade ⁇ Spike ⁇ OverTemp
  • thermocouple short-circuit fault can be diagnosed by real-time monitoring the sampling temperature variation obtained by each thermocouple group, the sampling temperature difference variation obtained by the thermocouple groups in each two adjacent temperature control zones, change in sampling temperature obtained by each thermocouple group while changing the power control of the corresponding heating unit, and changes in sampling temperature obtained by each thermocouple group and another thermocouple group (s) in adjacent temperature zone (s) while changing the power controls of the corresponding heating units.
  • the diagnosis result can be sent to the temperature controller to take correct and promptly measures according to the processing requirement, thereby reducing the loss of equipment and product.

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  • General Physics & Mathematics (AREA)
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Abstract

A system using fault diagnosis and treatment method for thermocouples in a heat treatment apparatus. Each temperature control zone in the heat treatment apparatus has a thermocouple group and a heating unit. The system comprises a filter, a temperature sensing module, a logical processor, a temperature controller and a power controller which form a control loop. The logical processor determines the working state of each thermocouple according to the sampling temperature variation of each temperature control zone, the temperature difference variation between each adjacent temperature control zones, the sampling temperature variation of each temperature control zone and the power control variation to each heating unit, and the sampling temperature variations of each adjacent temperature control zones and the power control variation to the corresponding heating units; and provides diagnosis result to the temperature controller and the power controller to perform corresponding compensation treatment.

Description

FAULT DIAGNOSIS AND TREATMENT METHOD AND SYSTEM FOR THERMOCOUPLES IN HEAT TREATMENT APPARATUS
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the priority of Chinese patent application number 201510068266.4_, filed on Feb. 10, 2015__, the entire contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
The present invention generally relates to the field of integrated circuit manufacturing, more particularly, to a fault diagnosis and treatment method and system for thermocouples used in a heat treatment apparatus.
BACKGROUND
Currently, the rapid development of high-integration and high-density semiconductor devices places more demands on new process, new technology and new equipment for semiconductor IC manufacturing. As one of the processing equipment used in IC front-end fabrication, heat treatment apparatus plays an important role in wafer manufacturing processes including diffusion, annealing, alloying, oxidation, and film formation, etc., and performs accurate temperature control to the wafer surfaces.
During the semiconductor manufacturing, the heat treatment apparatus is expected to run various processes continuously for a long time without failure, which puts forward a high request to the stability of the apparatus. As a measuring instrument of temperature control system, thermocouple has the features of high measuring precision, wide measuring range, small size, fast response, and long service life, and is widely applied in the heat treatment apparatus.
However, it is well-known by those skilled in the art that short-circuit fault or open-circuit fault may also occurs in the thermocouple, as shown in Fig. 1 which illustrates three different states of the thermocouple including normal state,  short-circuit fault state and open-circuit fault state. When the thermocouple is in the open-circuit fault state, a temperature sensing module of the temperature control system having open-circuit alarm function will output an alarm signal to a logic controller and thus the open-circuit fault can be detected easily. While when the thermocouple is in the short-circuit fault state, since the temperature data collected by the thermocouple changes with the location of the short-circuit point, and the short-circuit fault varies with the actual environment in which the thermocouple is involved, it is difficult to determine the short-circuit fault of the thermocouple.
BRIEF SUMMARY OF THE DISCLOSURE
Therefore, an object of the present invention is to provide a fault diagnosis and treatment method for thermocouples used in a heat treatment apparatus which enables correct diagnosis on whether the thermocouples are in the short-circuit fault state and provides information to a temperature controller accordingly, so that the temperature controller can take correct and promptly measures to meet the process requirement and reduce the loss of equipment and product.
To achieve these and other advantages and in accordance with the objective of the invention, the present invention provides a fault diagnosis and treatment method for thermocouples in a heat treatment apparatus. The heat treatment apparatus includes multiple temperature control zones each having a thermocouple group and a corresponding heating unit. The method comprises:
step S1: performing thermocouple fault diagnosis according to a sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group； if the diagnosis result is normal, turning to step S2；otherwise, turning to step S5；
step S2: performing thermocouple fault diagnosis according to a sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone obtained by the corresponding thermocouple groups； if the diagnosis result is normal, turning to step S3； otherwise, turning to step S5；
performing thermocouple fault diagnosis according to a change in sampling temperature in each temperature control zone obtained by the corresponding thermocouple group while changing the power control of each corresponding heating unit； if the diagnosis result is normal, turning to step S4； otherwise, turning to step S5；
step S4: performing thermocouple fault diagnosis according to changes in sampling temperature in each temperature control zone and its adjacent temperature control zone/zones obtained by the corresponding thermocouple groups while changing the power control of the heating units in each temperature control zone and its adjacent temperature control zone/zones, if the diagnosis result is normal, turning to step S1； otherwise, turning to step S5；
step S5: outputting a short-circuit alarming signal and performing corresponding compensation treatment.
Preferably, the step S1 comprises:
step S11: sampling the temperatures of each temperature control zone by the corresponding thermocouple group； calculating the sampling temperature variation in a sampling period of each temperature control zone according to the sampling temperatures of the temperature control zone；
step S12: during a normal temperature ramp upramp up period in a heat treatment process, determining whether the sampling temperature variation is greater than a first threshold value, and/or, during a normal temperature ramp downramp down period in the heat treatment process, determining whether the sampling temperature variation is less than a second threshold value； wherein, the first threshold value is a maximum temperature ramp upramp up value corresponding to the temperature control zone during the sampling period, the second threshold value is a negative value of a maximum temperature ramp downramp down value corresponding to the temperature control zone during the sampling period；
step S13: if yes, adding one to a first count value which represents short-circuit fault state；
step S14: repeating step S12 and step S13, if the first count value is greater than a preset value, outputting the short-circuit alarming signal.
Preferably, the step S2 comprises:
step S21: sampling the temperatures of each temperature control zone by the corresponding thermocouple group； and calculating the temperature difference variation between each temperature control zone and its adjacent temperature control zone according to the sampling temperatures obtained by the corresponding thermocouples；
step S22: during a normal temperature ramp up period in the heat treatment process, determining whether the temperature difference variation is greater than a third threshold value, and/or, during a normal temperature ramp down period in the heat treatment process, determining whether the temperature difference variation is e less than a fourth threshold value； wherein, the third threshold value is a maximum temperature ramp up difference between each temperature control zone and its adjacent temperature control zone, the fourth threshold value is a negative value of a maximum temperature ramp down difference between each temperature control zone and its adjacent temperature control zone；
step S23: if yes, adding one to a second count value which represents short-circuit fault state；
repeating the step S22 and the step S23, if the second count value is greater than a preset value, outputting the short-circuit alarming signal.
Preferably, the step S3 comprises:
step S31: calculating the power control variation during a control period to each heating unit according to the power outputs to the heating unit；
step S32: accumulating the sampling temperature variation of each temperature control zone by number of sampling time-delay cycles to obtain an accumulated sampling temperature variation of each temperature control zone； accumulating the power control variation by the number of the sampling time-delay cycles to obtain an accumulated power control variation to each heating unit； calculating an accumulated standard temperature variation of each temperature control zone corresponding to the accumulated power control variation to each heating unit according to a maximum temperature-ramp up power control rate, a maximum temperature-ramp down power control rate, a maximum temperature ramp up rate, and a maximum temperature ramp down rate of the temperature control  zone by using a linear interpolation method； determining whether the absolute value of the accumulated sampling temperature variation is greater than α-times the absolute value of the accumulated standard temperature variation of the same temperature control zone, wherein α is a system constant, the number of the sampling time-delay cycle is set according to thermocouple type, heating system time-delay constant and sampling system time-delay constant；
step S33: if yes, adding one to a third count value which represents short-circuit fault state；
step S34: repeating the step S32 and the step S33, if the third count value is greater than a preset value, outputting the short-circuit alarming signal.
Preferably, the α is between 1 and 2.
Preferably, the step S4 comprises:
step S41: calculating the power control variations during a control period to each heating unit；
step S42: accumulating the sampling temperature variations of each temperature control zone and its adjacent temperature control zone/zones by number of sampling time-delay cycles to obtain accumulated sampling temperature variations of each temperature control zone and its adjacent temperature control zone/zones； accumulating each of the power control variations by the number of the sampling time-delay cycles to obtain an accumulated power control variation of each temperature control zone； calculating accumulated standard temperature variations of each temperature control zone and its adjacent temperature control zone/zones corresponding to the accumulated power control variations to the corresponding heating units according to a maximum temperature-ramp up power control rate, a maximum temperature-ramp down power control rate, a maximum temperature ramp up rate, and a maximum temperature ramp down rate by using a linear interpolation method； determining whether the absolute value of the accumulated sampling temperature variation of each temperature control zone is greater than β-times the absolute value of the sum of the accumulated standard temperature variations of each temperature control zone and its adjacent temperature control zone/zones, wherein β is a system constant, the number of the sampling time-delay cycle is set  according to thermocouple type, heating system time-delay constant and sampling system time-delay constant
step S43: if yes, adding one to a fourth count value which represents short-circuit fault state；
step S44: repeating the step S42 and the step S43, if the fourth count value is greater than a preset value, outputting the short-circuit alarming signal.
Preferably, the β is between 0 and 1.
Preferably, each thermocouple group comprises an inner thermocouple disposed within a processing tube of the heat treatment apparatus, a first outer thermocouple and a second outer thermocouple disposed outside the processing tube close to the corresponding heating unit, and an overtemperature thermocouple disposed close to the first and second outer thermocouples； the step 5 comprises: switching temperature control mode from inner thermocouple-based mode to first outer thermocouple-based mode, or from first outer thermocouple-based mode to second outer thermocouple-based mode, or from second outer thermocouple-based mode to overtemperature thermocouple-based mode in turn, and continuing the process.
The present invention also provides a system using the fault diagnosis and treatment method mentioned above. The heat treatment apparatus includes multiple temperature control zones each having a thermocouple group and a heating unit. The system comprises a filter, a temperature sensing module, a logical processor, a temperature controller and a power controller which form a control loop； the temperatures sampled by each of the thermocouple groups are processed by the filter, the temperature sensing module and the logical processor, wherein the logical processor determines the current working state of each thermocouple according to the sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group, the sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone obtained by the corresponding thermocouple groups, the sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple groups and the power control variation to each heating unit, and the sampling temperature variations of each temperature control zone and its adjacent  temperature control zone/zones and the power control variations to the corresponding heating units in each temperature control zone and its adjacent temperature control zone/zones； and provides diagnosis result to the temperature controller and the power controller to perform corresponding compensation treatment.
Preferably, each thermocouple group comprises an inner thermocouple disposed within a processing tube of the heat treatment apparatus, a first outer thermocouple and a second outer thermocouple disposed outside the processing tube close to the corresponding heating unit, and an overtemperature thermocouple disposed close to the first and second outer thermocouples, the corresponding compensation treatment comprises: switching temperature control mode from inner thermocouple-based mode to first outer thermocouple-based mode, or from first outer thermocouple-based mode to second outer thermocouple-based mode, or from second outer thermocouple-based mode to overtemperature thermocouple-based mode in turn, and continuing the process.
According to the present invention, thermocouple short-circuit fault can be diagnosed by real-time monitoring the sampling temperature variation obtained by each thermocouple group, the sampling temperature difference variation obtained by each thermocouple group and another thermocouple group in an adjacent temperature control zone, change in sampling temperature obtained by each thermocouple group while changing the power control of the corresponding heating unit, and changes in sampling temperature obtained by each thermocouple group and another thermocouple group (s) in adjacent temperature zone (s) while changing the power controls of the corresponding heating units. The diagnosis result can be sent to the temperature controller to take correct and promptly measures according to the processing requirement, thereby reducing the loss of equipment and product.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that objects, characteristics, and advantages of the present invention may be more fully understood, the embodiments of the present invention will now be described in detail hereafter with reference to the accompanying drawings, wherein
Fig. 1 illustrates the three states of a thermocouple used in a heat treatment apparatus including normal state, short-circuit state and open-circuit state；
Fig. 2 is a schematic diagram showing five temperature control zones and five heating units in the heat treatment apparatus；
Fig. 3 is a block chart showing the power control system utilizing the thermocouple fault diagnosis and treatment method of the present invention；
Fig. 4 is a flow chart showing the thermocouple fault diagnosis and treatment method according to an embodiment of the present invention’
Fig. 5 illustrates the maximum temperature differences in temperature control zone_i and temperature control zone_i+1；
Fig. 6 illustrates the maximum temperature differences in temperature control zone_n and temperature control zone_n-1；
Fig. 7 illustrates the maximum temperature differences in temperature control zone_i+j and temperature control zone_i+j+1 (i+j+1<n) ；
Fig. 8 illustrates thermocouple fault diagnosis steps according to the sampling temperature variation obtained by each thermocouple group；
Fig. 9 illustrates thermocouple fault diagnosis steps according to the sampling temperature difference variation obtained by each thermocouple group and another thermocouple group in an adjacent temperature control zone；
Fig. 10 illustrates thermocouple fault diagnosis steps according to the sampling temperature variation obtained by each thermocouple group and the power control variation to the heating unit corresponding to the thermocouple group；
Fig. 11 illustrates thermocouple fault diagnosis steps according to the sampling temperature variations obtained by each thermocouple group and another thermocouple groups in adjacent temperature control zones and the power control variations to the heating units in the temperature control zone corresponding to the thermocouple group and its adjacent temperature control zones.
DETAILED DESCRIPTION
The present invention will be described in further details hereinafter with respect to the embodiments and the accompany drawings Fig. 1 to Fig. 11.
It is noted that the present invention aims to determine the working state of the thermocouple based on the sampling temperature and take corresponding measures when the thermocouple is determined to be in the short-circuit fault state, thereby preventing the decrease of the process effect； furthermore, the heat treatment processing can be ensured proceeding through compensation treatment such as using different thermocouples and switching the temperature control mode correspondingly, which minimize the losses.
In the following embodiment of the present invention, the heat treatment apparatus can be divided into multiple temperature control zones as required. In each temperature control zone, multiple thermocouples and a heating unit can be provided, and the multiple thermocouples can be of different types.
Fig. 2 is a schematic diagram showing five temperature control zones and the corresponding five heating units. Referring to Fig. 2, the heat treatment apparatus has five temperature control zones (zone1, zone2, zone3, zone 4, and zone 5) each comprising a thermocouple group and a heating unit. Each thermocouple group comprises four thermocouples, that is, an inner thermocouple (Inner TC) which is disposed within a processing tube of the heat treatment apparatus, a first outer thermocouple (OuterA TC) and a second outer thermocouple (OuterB TC) disposed outside the processing tube close to the corresponding heating unit, and an overtemperature thermocouple (OverTemp TC) disposed close to the first and second outer thermocouples.
Fig. 3 is a block chart showing the power control system utilizing the thermocouple fault diagnosis and treatment method of the present invention. As shown in Fig. 3, the system also comprises a filter, a temperature sensing module, a logical processor, a temperature controller and a power controller which form a control loop.
The temperatures sampled by the five thermocouple groups (thermocouples 1～5 in Fig. 3) are processed by the filter, the temperature sensing  module and the logical processor. The logical processor determines the working state of the thermocouples according to a sampling temperature variation obtained by each thermocouple group during a sampling period, a sampling temperature difference variation obtained by each thermocouple group and another thermocouple group in an adjacent temperature control zone, the sampling temperature variation obtained by each thermocouple group and power control variation to the heating unit corresponding to the thermocouple group during a control period, and the sampling temperature variations obtained by each thermocouple group and another thermocouple group (s) in the adjacent temperature control zone (s) and the power control variations to the corresponding heating units during the control period, and then provides the diagnosis result to the temperature controller and the power controller to perform corresponding compensation treatment.
For clarity, some terms in the description will be explained as follows.
During the normal operation of the heating system of the heat treatment apparatus, maximum temperature-ramp up rate and maximum temperature-ramp down rate in each temperature control zone at different temperature ranges are recorded, as shown in Table 1.
Figure PCTCN2015076715-appb-000001
Table 1
During normal temperature ramp up period in the heat treatment process, the temperature of each temperature control zone is sampled continuously for n times by the corresponding thermocouple group. Wherein, each sampling temperature variation ΔT (unit ℃) in a sampling period Δt (unit second) obtained by the thermocouple group should be equal to or less than a first threshold value TH1. The first threshold value TH1 is a maximum temperature ramp up value during the sampling period, it can be calculated according to the following formula: TH1 ＝RampUpRatemax ＊Δt/60, wherein RampUpRatemax (unit ℃/Min) is the maximum temperature ramp up rate which can be obtained from the Table 1.
During normal temperature ramp down period in the heat treatment process, the temperature of each temperature control zone is sampled continuously for n times by the corresponding thermocouple group. Wherein, each sampling temperature variation ΔT (unit ℃) in the sampling period Δt (unit second) obtained by the thermocouple group should be equal to or greater than a second threshold value TH2. The second threshold value TH2 is the negative value of a maximum temperature ramp down value during the sampling period, it can be calculated according to the following formula: TH2＝-RampDownRatemax ＊Δt /60, wherein RampDownRatemax (unit ℃/Min) is the maximum temperature ramp down rate which can be obtained from the Table 1。
The RampUPRatemax represents the measured temperature variation per minute in the temperature control zone (TMin (i+1) -TMin (i) ) when full power is outputted to the corresponding heating unit in the temperature control zone, the measured value varies with the temperature range and the working time of the heating unit. In order to obtain the maximum temperature ramp up rate within the temperature range, the sampling time should be selected and the sampling period should be calibrated.
The RampDownRatemax represents the measured temperature variation per minute in the temperature control zone (TMin (i+1) -TMin (i) ) when no power is outputted to the corresponding heating unit in the temperature control zone, the measured value varies with the temperature range and the working time of the heating unit. In order to obtain the maximum temperature ramp down rate within the temperature range, the sampling time should be selected and the sampling period should be calibrated.
The maximum temperature ramp up difference ΔTNearMaxUp in two adjacent temperature control zones represents the temperature difference between the temperatures sampled in two adjacent temperature control zones (adjacent temperature control zone and current temperature control zone) , wherein full power is outputted to the heating unit in the current temperature control zone and no power is outputted to the heating unit in the adjacent temperature control zone. The temperature difference varies with the temperature range and the working time of the heating units. The sampling time should be selected and the sampling period should be calibrated.
The maximum temperature ramp down difference ΔTNearMaxDown in two adjacent temperature control zones is the temperature difference between the temperatures in two adjacent temperature control zones (adjacent temperature control zone and current temperature control zone) , wherein no power is outputted to the heating unit in the current temperature control zones and full power is outputted to the heating unit in the adjacent temperature control zone. The temperature difference varies with the temperature range and the working time of the heating units. The sampling time should be selected and the sampling period should be calibrated.
For multiple temperature control zones (as shown in Fig. 3) , three kinds of temperature difference in the adjacent temperature control zones are provided, as shown in Figs. 5～7, each kind of temperature difference includes a positive variation value and a negative variation value. ΔTNearMaxUp＝TZone (i+1) -TZone (i) ＝TH3, ΔTNearMaxDown＝TZone (i) -TZone (i+1) ＝-TH4.
The thermocouple fault diagnosis and treatment method will be described in further details with reference to Fig. 4. As shown in Fig. 4, the method comprises the following steps:
step S1: performing thermocouple fault diagnosis according to a sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group； if the diagnosis result is normal, turning to step S2； otherwise, turning to step S5；
step S2: performing thermocouple fault diagnosis according to a sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone obtained by the corresponding thermocouple groups； if the diagnosis result is normal, turning to step S3； otherwise, turning to step S5；
step S3: performing thermocouple fault diagnosis according to a change in sampling temperature in each temperature control zone obtained by the corresponding thermocouple group while changing the power control of each corresponding heating unit； if the diagnosis result is normal, turning to step S4； otherwise, turning to step S5；
step S4: performing thermocouple fault diagnosis according to changes in sampling temperature in each temperature control zone and its adjacent temperature control zone/zones obtained by the corresponding thermocouple groups while changing the power controls of the heating units in each temperature control zone and its adjacent temperature control zone/zones, if the diagnosis result is normal, turning to step S1； otherwise, turning to step S5；
S5: outputting a short-circuit alarming signal and performing corresponding compensation treatment. When the short-circuit fault of the thermocouple is diagnosed, the compensation treatment is performed by using other thermocouples in the thermocouple group instead for temperature measurement and temperature control. In the embodiment, the temperature control mode can be switched from Inner TC-based mode to OuterA TC-based mode, or from OuterA TC-based mode to OuterB TC-based mode, or from OuterB TC-based mode to OverTemp TC based mode in turn, so as to continue the process.
Referring to Fig. 8, which illustrates the thermocouple fault diagnosis steps according to the sampling temperature variation obtained by each thermocouple group according to a preferred embodiment of the present invention, step S1 further comprises:
step S11: initializing a first count value which represents short-circuit fault state, that is, setting iCount1＝0； sampling the temperatures of each temperature control zone by the corresponding thermocouple group； calculating the sampling temperature variation ΔT during the sampling period Δt of the temperature control  zone according to the sampling temperatures of the temperature control zone, which meets the formula ΔT＝Tt+Δt-Tt；
step S12: during a normal temperature ramp up period in a heat treatment process, determining whether the sampling temperature variation is greater than a first threshold value TH1 (ΔT>TH1) , and/or, during a normal temperature ramp down period in the heat treatment process, determining whether the sampling temperature variation is less than a second threshold value TH2 (ΔT<TH2) ； wherein, the first threshold value is a maximum temperature ramp up value in the sampling period (TH1＝RampUpRatemax ＊Δt /60) , the second threshold value is the negative value of a maximum temperature ramp down value in the sampling period (TH2＝-RampDownRatemax ＊Δt /60) ；
step S13: if yes, that is, ifΔT> TH1 orΔT<TH2, adding one to the first count value iCount1； otherwise, if TH2≤ΔT≤TH1, keeping the first count value iCount1 the same；
step S14: repeating step S12 and step S13, if the first count value iCount1 is greater than a preset value, outputting the short-circuit alarming signal.
In the embodiment, if the diagnosis result obtained from step S1 is normal, step S2 can be performed for further diagnosis. As shown in Fig. 9, which illustrates the thermocouple fault diagnosis steps according to the sampling temperature difference variation obtained by each thermocouple group and another thermocouple group in an adjacent temperature control zone, step S2 further comprises:
step S21: initializing a second count value which represents short-circuit fault state, that is, setting iCount2＝0； sampling the temperatures of each temperature control zone and its adjacent temperature control zone by the corresponding thermocouple groups； calculating the sampling temperature difference variation ΔTNearZone of the two adjacent temperature control zones according to the sampling temperatures of each of the temperature control zones, that is, TNearZone＝TZone (i+1) -TZone (i) ；
step S22: during the normal temperature ramp up period in the heat treatment process, determining whether the sampling temperature difference  variation is greater than a third threshold value TH3, and/or, during the normal temperature ramp down period, determining whether the sampling temperature difference variation is less than a fourth threshold value TH4； wherein, the third threshold value TH3 is the maximum temperature ramp up difference of two adjacent temperature control zones ΔTNearMaxUp, the fourth threshold value TH4 is a negative value of the maximum temperature ramp down difference of two adjacent temperature control zones TNearMaxDown；
step S23: if yes, that is, if ΔTNearZone>ΔTNearMaxUp＝TH3 or ΔTNearZone<-ΔTNearMaxDown＝TH4, adding one to the second count value iCount2； otherwise, if TH4<ΔTNearZone <TH3, keeping the second count value iCount2 the same；
step S24: repeating step s22 and step s23, if the second count value iCount2 is greater than a preset value, outputting the short-circuit alarming signal.
In the embodiment, if the diagnosis result obtained from step S2 is normal, step S3 can be performed for further diagnosis. As shown in Fig. 10, which illustrates the thermocouple fault diagnosis steps according to the temperature variation obtained by each thermocouple group and the power control variation to the heating unit corresponding to the thermocouple, step S3 further comprises:
step S31: initializing a third count value which represents short-circuit fault state, that is, setting iCount3＝0； calculating the power control variation ΔCtrlOutZone (i) during a control period Δt1 to the heating unit corresponding to the thermocouple group (for example, in the ith temperature control zone) according to the power outputs to the heating unit in the ith temperature control zone, that is, ΔCtrlOutZone (i) ＝CtrlOutZone (i) t+Δt1-CtrlOutZone (i) t. Wherein, the power control variation ΔCtrlOutZone (i) during the control period Δt1 will lead to a corresponding temperature variation ΔTΔCtrlOut, and the temperature variation caused by the power control variation can be calculated by a linear interpolation method.
step S32: accumulating the sampling temperature variation ΔT of the ith temperature control zone obtained by the corresponding thermocouple group by number of sampling time-delay cycles NCycle to obtain an accumulated sampling  temperature variation
Figure PCTCN2015076715-appb-000002
of the ith temperature control zone； accumulating the power control variation CtrlOutZone (i) by the number of the sampling time-delay cycles NCycle to obtain an accumulated power control variation 
Figure PCTCN2015076715-appb-000003
to the heating unit in the ith temperature control zone； calculating an accumulated standard temperature variation ΔTStandard (i) corresponding to the accumulated temperature control variation 
Figure PCTCN2015076715-appb-000004
according to a maximum temperature-ramp up control rate CtrlRampUpRatemax, a maximum temperature-ramp down control rate CtrlRampDownRatemax, a maximum temperature ramp up rate RampUpRatemax, and a maximum temperature ramp down rate RampDownRatemax of the ith temperature control zone by using the linear interpolation method； determining whether the absolute value of the accumulated sampling temperature variation is greater than α-times the absolute value of the accumulated standard temperature variation 
Figure PCTCN2015076715-appb-000005
wherein the maximum temperature-ramp up control rate CtrlRampUpRatemax and the maximum temperature-ramp down control rate CtrlRampDownRatemax is predetermined, the maximum temperature ramp up rate RampUpRatemax and the maximum temperature ramp down rate RampDownRatemax can be obtained from table 1； α is a system constant between 1 and 2, the number of the sampling time-delay cycle is set according to thermocouple type, heating system time-delay constant and sampling system time-delay constant；
step S33: if yes, that is, if
Figure PCTCN2015076715-appb-000006
adding one to the third count value iCount3； otherwise, keeping the third count value iCount3 the same；
step S34: repeating step s32 and step s33, if the third count value iCount3 is greater than a preset value, outputting the short-circuit alarming signal.
In the embodiment, if the diagnosis result obtained from step S3 is normal, step S4 can be performed for further diagnosis. As shown in Fig. 11, which illustrates the thermocouple fault diagnosis steps according to the temperature variations obtained by each thermocouple group and another thermocouple group (s) in the adjacent temperature control zone (s) and the power control variations to the corresponding heating units, step S4 further comprises:
step S41: initializing a fourth count value which represents short-circuit fault state, that is, setting iCount4＝0； calculating the power control variations during the control period Δt1 to the heating units in the ith temperature control zone and two temperature control zones adjacent to the ith temperature control zone (ΔCtrlOut Zone (i-1) , ΔCtrlOut Zone (i) , ΔCtrlOut Zone (i+1) ) according to the power outputs to the heating units in these three temperature control zones； that is,
ΔCtrlOut Zone (i-1) ＝CtrlOutZone (i-1) t+Δt1-CtrlOutZone (i-1) t；
ΔCtrlOut Zone (i+1) ＝CtrlOutZone (i+1) t+Δt1-CtrlOutZone (i+1) t；
Wherein, the power control variation ΔCtrlOutZone (i) /ΔCtrlOut Zone (i-1) /ΔCtrlOut Zone (i+1) during the control period Δt1 will lead to a corresponding temperature variation ΔTΔCtrlOut, and the temperature variation caused by the power control variation can be calculated by a linear interpolation method；
step S42: accumulating the sampling temperature variation ΔT of each of the three temperature control zones obtained by the corresponding thermocouple groups by number of sampling time-delay cycles NCycle to obtain an accumulated sampling temperature variation
Figure PCTCN2015076715-appb-000007
of each of the temperature control zones； accumulating each of the power control variations CtrlOutZone (i) , ΔCtrlOut Zone (i-1) , ΔCtrlOut Zone (i+1) by the number of the sampling time-delay cycles NCycle to obtain the accumulated power control variations
Figure PCTCN2015076715-appb-000008
Figure PCTCN2015076715-appb-000009
Figure PCTCN2015076715-appb-000010
calculating the accumulated standard temperature variations ΔTStandard (i) , ΔTStandard (i-1) , ΔTStandard (i+1) corresponding to the accumulated power control variations
Figure PCTCN2015076715-appb-000011
Figure PCTCN2015076715-appb-000012
according to the maximum temperature-ramp up control rate CtrlRampUpRatemax, the maximum temperature-ramp down control rate CtrlRampDownRatemax, the maximum temperature ramp up value RampUpRatemax, and the maximum temperature ramp down value  RampDownRatemax of each of the three temperature control zones by using the linear interpolation method； determining whether the absolute value of each of the accumulated sampling temperature variation of the three temperature control zones is greater than β-times the absolute value of the sum of the three accumulated standard temperature variations
Figure PCTCN2015076715-appb-000013
Figure PCTCN2015076715-appb-000014
wherein β is a system constant between 0 and 1, the number of the sampling time-delay cycle is set according to thermocouple type, heating system time-delay constant and sampling system time-delay constant.
step S43: if yes, adding one to the fourth count value iCount4； otherwise, keeping the fourth count value iCount4 the same；
step S44: repeating step s42 and step s43, if the fourth count value iCount4 is greater than a preset value, outputting the short-circuit alarming signal.
When the logical controller determines that a thermocouple in the thermocouple group is in the short-circuit fault state, it sends the alarming signal to the temperature controller to use other thermocouples (Inner TC→OuterA TC →OuterB TC→OverTemp TC) and switch temperature controlling method (Cascade→Spike→OverTemp) , so as to ensure the proceeding of the heat treatment process.
In summary, according to the present invention, thermocouple short-circuit fault can be diagnosed by real-time monitoring the sampling temperature variation obtained by each thermocouple group, the sampling temperature difference variation obtained by the thermocouple groups in each two adjacent temperature control zones, change in sampling temperature obtained by each thermocouple group while changing the power control of the corresponding heating unit, and changes in sampling temperature obtained by each thermocouple group and another thermocouple group (s) in adjacent temperature zone (s) while changing the power controls of the corresponding heating units. The diagnosis result can be sent to the temperature controller to take correct and promptly measures according to the processing requirement, thereby reducing the loss of equipment and product.
While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in  the art that various changes in form and details may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

  1. A fault diagnosis and treatment method for thermocouples in a heat treatment apparatus, the heat treatment apparatus includes multiple temperature control zones each having a thermocouple group and a corresponding heating unit, the method comprises:
    step S1: performing thermocouple fault diagnosis according to a sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group； if the diagnosis result is normal, turning to step S2； otherwise, turning to step S5；
    step S2: performing thermocouple fault diagnosis according to a sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone obtained by the corresponding thermocouple groups； if the diagnosis result is normal, turning to step S3； otherwise, turning to step S5；
    step S3: performing thermocouple fault diagnosis according to a change in sampling temperature in each temperature control zone obtained by the corresponding thermocouple group while changing the power control of each corresponding heating unit； if the diagnosis result is normal, turning to step S4； otherwise, turning to step S5；
    step S4: performing thermocouple fault diagnosis according to changes in sampling temperature in each temperature control zone and its adjacent temperature control zone/zones obtained by the corresponding thermocouple groups while changing the power controls of the heating units in each temperature control zone and its adjacent temperature control zone/zones, if the diagnosis result is normal, turning to step S1； otherwise, turning to step S5；
    step S5: outputting a short-circuit alarming signal and performing corresponding compensation treatment.
  2. The method according to claim 1, wherein the step S1 comprises:
    step S11: sampling the temperatures of each temperature control zone by the corresponding thermocouple group； calculating the sampling temperature variation in a  sampling period of each temperature control zone according to the sampling temperatures of the temperature control zone；
    step S12: during a normal temperature ramp up period in a heat treatment process, determining whether the sampling temperature variation is greater than a first threshold value, and/or, during a normal temperature ramp down period in the heat treatment process, determining whether the sampling temperature variation is less than a second threshold value； wherein, the first threshold value is a maximum temperature ramp up value corresponding to the temperature control zone during the sampling period, the second threshold value is a negative value of a maximum temperature ramp down value corresponding to the temperature control zone during the sampling period；
    step S13: if yes, adding one to a first count value which represents short-circuit fault state；
    step S14: repeating step S12 and step S13, if the first count value is greater than a preset value, outputting the short-circuit alarming signal.
  3. The method according to claim 1, wherein the step S2 comprises:
    step S21: sampling the temperatures of each temperature control zone by the corresponding thermocouple group； and calculating the sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone according to the sampling temperatures obtained by the corresponding thermocouple groups；
    step S22: during a normal temperature ramp up period in the heat treatment process, determining whether the sampling temperature difference variation is greater than a third threshold value, and/or, during a normal temperature ramp down period in the heat treatment process, determining whether the sampling temperature difference variation is less than a fourth threshold value； wherein, the third threshold value is a maximum temperature ramp up difference between each temperature control zone and its adjacent temperature control zone, the fourth threshold value is a negative value of a maximum temperature ramp down difference between each temperature control zone and its adjacent temperature control zone；
    step S23: if yes, adding one to a second count value which represents short-circuit fault state；
    repeating the step S22 and the step S23, if the second count value is greater than a preset value, outputting the short-circuit alarming signal.
  4. The method according to claim 1, wherein the step S3 comprises:
    step S31: calculating the power control variation during a control period to each heating unit according to the power outputs to the heating unit；
    step S32: accumulating the sampling temperature variation of each temperature control zone by number of sampling time-delay cycles to obtain an accumulated sampling temperature variation of each temperature control zone； accumulating the power control variation by the number of the sampling time-delay cycles to obtain an accumulated power control variation to each heating unit； calculating an accumulated standard temperature variation of each temperature control zone corresponding to the accumulated power control variation to each heating unit according to a maximum temperature-ramp up power control rate, a maximum temperature-ramp down power control rate, a maximum temperature ramp up rate, and a maximum temperature ramp down rate of the temperature control zone by using a linear interpolation method； determining whether the absolute value of the accumulated sampling temperature variation of each temperature control zone is greater than α-times the absolute value of the accumulated standard temperature variation of the same temperature control zone, wherein α is a system constant, the number of the sampling time-delay cycle is set according to thermocouple type, heating system time-delay constant and sampling system time-delay constant；
    step S33: if yes, adding one to a third count value which represents short-circuit fault state；
    step S34: repeating the step S32 and the step S33, if the third count value is greater than a preset value, outputting the short-circuit alarming signal.
  5. The method according to claim 4, wherein the α is between 1 and 2.
  6. The method according to claim 1, wherein the step S4 comprises:
    step S41: calculating the power control variation during a control period to each heating unit according to the power outputs to the heating unit；
    step S42: accumulating the sampling temperature variations of each temperature control zone and its adjacent temperature control zone/zones by number of sampling time-delay cycles to obtain accumulated sampling temperature variations of each temperature control zone and its adjacent temperature control zone/zones； accumulating each of the power control variations by the number of the sampling time-delay cycles to obtain an accumulated power control variation of each temperature control zone； calculating accumulated standard temperature variations of each temperature control zone and its adjacent temperature control zone/zones corresponding to the accumulated power control variations to the corresponding heating units according to a maximum temperature-ramp up power control rate, a maximum temperature-ramp down power control rate, a maximum temperature ramp up rate, and a maximum temperature ramp down rate by using a linear interpolation method； determining whether the absolute value of the accumulated sampling temperature variation of each temperature control zone is greater than β-times the absolute value of the sum of the accumulated standard temperature variations of each temperature control zone and its adjacent temperature control zone/zones, wherein β is a system constant, the number of the sampling time-delay cycle is set according to thermocouple type, heating system time-delay constant and sampling system time-delay constant；
    step S43: if yes, adding one to a fourth count value which represents short-circuit fault state；
    step S44: repeating the step S42 and the step S43, if the fourth count value is greater than a preset value, outputting the short-circuit alarming signal.
  7. The method according to claim 6, wherein the β is between 0 and 1.
  8. The method according to claim 1, wherein each thermocouple group comprises an inner thermocouple disposed within a processing tube of the heat treatment apparatus, a first outer thermocouple and a second outer thermocouple disposed outside the processing tube close to the corresponding heating unit, and an  overtemperature thermocouple disposed close to the first and second outer thermocouples； the step 5 comprises: switching temperature control mode from inner thermocouple-based mode to first outer thermocouple-based mode, or from first outer thermocouple-based mode to second outer thermocouple-based mode, or from second outer thermocouple-based mode to overtemperature thermocouple-based mode in turn, and continuing the process.
  9. A system using the fault diagnosis and treatment method according to claim 1, wherein the heat treatment apparatus includes multiple temperature control zones each having a thermocouple group and a heating unit； wherein,
    the system comprises a filter, a temperature sensing module, a logical processor, a temperature controller and a power controller which form a control loop； the temperatures sampled by each of the thermocouple groups are processed by the filter, the temperature sensing module and the logical processor, wherein the logical processor determines the current working state of each thermocouple according to the sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group, the sampling temperature difference variation between each temperature control zone and its adjacent temperature control zone obtained by the corresponding thermocouple groups, the sampling temperature variation of each temperature control zone obtained by the corresponding thermocouple group and the power control variation to each heating unit, and the sampling temperature variations of each temperature control zone and its adjacent temperature control zone/zones and the power control variations to the corresponding heating units in each temperature control zone and its adjacent temperature control zone/zones； and provides diagnosis result to the temperature controller and the power controller to perform corresponding compensation treatment.
  10. The system according to claim 9, wherein each thermocouple group comprises an inner thermocouple disposed within a processing tube of the heat treatment apparatus, a first outer thermocouple and a second outer thermocouple disposed outside the processing tube close to the corresponding heating unit, and an overtemperature thermocouple disposed close to the first and second outer  thermocouples, the corresponding compensation treatment comprises: switching temperature control mode from inner thermocouple-based mode to first outer thermocouple-based mode, or from first outer thermocouple-based mode to second outer thermocouple-based mode, or from second outer thermocouple-based mode to overtemperature thermocouple-based mode in turn, and continuing the process.
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