Vacuum gauge

Abstract

The present invention provides a vacuum gauge capable of preventing accumulation of a substance on a sensing mechanism even when the sensing mechanism is exposed to an atmosphere into which various material gases are introduced, and capable of achieving a long life. The vacuum gauge comprises a sensing mechanism which is in contact with atmosphere in a measurement space and outputs an output signal corresponding to pressure in the measurement space; and a heater for adjusting the temperature of the sensing mechanism, the set temperature of the heater being variable.

Description

[0001] This application is a divisional application of patent application No. 201811425237.9 with a filing date of November 27, 2018, and with the title "Vacuum gauge". TECHNICAL FIELD

[0002] The present application relates to a vacuum gauge. BACKGROUND

[0003] For example, in semiconductor processing, a vacuum gauge for monitoring the degree of vacuum in a vacuum chamber in which film formation is performed is provided. As shown in Patent Literature 1, the vacuum gauge includes a sensing mechanism exposed to the atmosphere in the vacuum chamber, and a pressure calculation circuit that inputs an output signal output from the sensing mechanism in correspondence with the pressure, and converts it into a pressure signal indicating the pressure.

[0004] In recent years, along with miniaturization of semiconductor processing, various kinds of material gases are introduced into the vacuum chamber, and among the new material gases, there are gases having a condensation temperature much higher than that of the conventional material gases.

[0005] Therefore, a part of the material gas that easily condenses condenses on the sensing mechanism, and its components accumulate, and problems such as a decrease in sensitivity to the pressure, a shortening of the life as a sensor, and the like occur. If accumulation occurs on the sensing mechanism, it is necessary to replace the entire vacuum gauge from the vacuum chamber, and since time is taken for replacement and calibration, the downtime of the semiconductor manufacturing process becomes longer, and productivity deteriorates.

[0006] In addition, if a high temperature is set in order to prevent the material gas from condensing, decomposition occurs, and sometimes the film formation of the intended components cannot be achieved. Therefore, the current situation is that when various material gases are introduced into the vacuum chamber, a vacuum gauge corresponding to the characteristics of the material gas is prepared separately.

[0007] PRIOR ART DOCUMENTS

[0008] Patent Literature 1: Japanese Patent Publication No. 4437578 SUMMARY

[0009] The present application is made to solve the problems as described above, and the object of the present application is to provide a vacuum gauge that can prevent accumulation of substances to a sensing mechanism even when the sensing mechanism is exposed to an atmosphere in which various material gases are introduced, and can achieve long life.

[0010] The vacuum gauge of the present application includes a sensing mechanism that contacts the atmosphere in a measurement space and outputs an output signal corresponding to the pressure in the measurement space, and a heater that temperature-regulates the sensing mechanism, and the set temperature of the heater is variable.

[0011] According to such a vacuum gauge, it is possible to maintain a temperature in the sensing mechanism at which no condensation of gas occurs, for example, based on a condensation temperature and a decomposition temperature of a gas present in a measurement space, and to prevent accumulation of components of the gas to the sensing mechanism even when various gases are introduced into the measurement space.

[0012] Therefore, since it is possible to maintain the sensitivity as a vacuum gauge for a long period of time and extend the life thereof, it is possible to reduce the frequency of occurrence of downtime in semiconductor processing, for example, and thereby improve productivity.

[0013] In order to achieve temperature control of the heater only within the vacuum gauge without receiving a temperature control signal for controlling the heater from the outside of the vacuum gauge, and simplify the structure of wiring and the like, it is preferable that the vacuum gauge include a sensor module that includes the sensing mechanism, and a main module that includes a pressure calculation circuit that inputs an output signal of the sensing mechanism and calculates a pressure value, and a heater control circuit that controls the temperature of the heater, the heater control circuit controlling current or voltage of the heater in such a manner that the temperature of the heater becomes a set temperature inputted.

[0014] Even when sufficient temperature adjustment is performed on the sensing mechanism, there is a case where accumulation of components of the gas occurs although in a small amount and replacement of the vacuum gauge is eventually required. In order to make it possible to replace only the problematic sensing mechanism part without replacing the entire vacuum gauge even in such a case, for example, to make the downtime in semiconductor processing minimum, it is preferable that the sensor module be detachable with respect to the main module.

[0015] In a conventional vacuum gauge in which the sensor module and the main module part are not detachable, when the life of the vacuum gauge is exhausted, the entire vacuum gauge is replaced, and calibration is performed on the spot, for example. Therefore, the time required for calibration, for example, the downtime in semiconductor processing, is correspondingly lengthened. In order to shorten or eliminate the time for such calibration work, it is preferable that the pressure calculation circuit include a calibration data storage part that stores calibration data corresponding to the sensing mechanism, and a pressure calculation part that calculates a pressure value based on an output signal of the sensing mechanism and the calibration data, the calibration data storage part being capable of updating calibration data by external input. According to such a configuration, calibration work is performed on each sensor module in advance at a manufacturer of the vacuum gauge, for example, and the calibration data is sold together with the sensor module, and at the time of replacement work, only the calibration data corresponding to the new sensor module is rewritten in the calibration data storage part, and an accurate pressure value is obtained immediately.

[0016] Since various gases are introduced into the measurement space, in order to be able to not impair the accuracy of the pressure value calculated by the pressure calculation circuit due to the difference in temperature even when the set temperature of the heater is appropriately changed, it is preferable that the pressure calculation circuit further include a correction coefficient storage section that stores a correction coefficient corresponding to the set temperature of the heater, and a correction section that corrects the pressure value calculated by the pressure calculation section according to the correction coefficient.

[0017] Even in the case where the heater has to be kept at a high temperature in order to prevent the components of the gas from accumulating to the sensing mechanism, it is possible to make the pressure calculation circuit not suffer from malfunction and failure due to the influence of the heat, and it is preferable that the vacuum gauge further include a heat insulation module that separates the sensor module and the main module by a prescribed distance and hinders the heat generated by the sensor module from being transmitted to the main module.

[0018] In order to reliably prevent the deviation of the position of the heater with respect to the sensing mechanism from being unable to achieve the desired temperature adjustment state when the sensor module is replaced with respect to the main module, and to always be able to achieve the ideal temperature adjustment, it is preferable that the sensing mechanism of the sensor module be integrated with the heater, and that the sensor module be detachable with respect to the main module.

[0019] In order to make the sensor module able to be easily mounted with respect to the main module even in the case where a plurality of lines are required in order to perform the transmission and reception of signals between the main module and the sensor module, without being affected by the dimensional error and positional error of each component, it is preferable that the main module further have a heater control circuit that controls the temperature of the heater, and that a main connector that connects between the sensing mechanism and the pressure calculation circuit, and a sub-connector that connects between the heater and the heater control circuit be provided to the heat insulation module, at least one of the main connector and the sub-connector having flexibility.

[0020] In order to make the influence of the noise difficult to be superimposed on the output signal of the sensing mechanism, and thus obtain an accurate pressure value, even in the case where the separation distance of the main module and the sensor module is large, and the noise from the outside is likely to be incident to the main connector, it is preferable that the main connector include a center conductor that transmits the output signal of the sensing mechanism, an electrically insulating cylindrical insulator that covers the side peripheral surface of the center conductor, and an outer conductor that covers the outer side peripheral surface of the insulator, and that a connector socket of the conductor system be provided to the heat insulation module, the connector socket covering the further outer side of the outer conductor.

[0021] According to the vacuum gauge of the present application, since the set temperature of the heater that temperature-regulates the sensing mechanism is variable, even in the case where various gases are introduced into the measurement space, it is possible to prevent the components of the gas from accumulating to the sensing mechanism by setting the temperature corresponding to the kind of the gas. Therefore, for example, even in the case where miniaturization accompanying semiconductor processing and use of a material gas that easily condenses are used, it is possible to prevent the life of the vacuum gauge from being shortened, and it is possible to reduce the frequency of occurrence of the downtime of the semiconductor processing. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a perspective view showing a vacuum gauge of one embodiment of the present application.

[0023] Figure 2 is a cross-sectional view showing the vacuum gauge of the same embodiment.

[0024] Figure 3 is a perspective view showing a state where a sensor module is detached from the vacuum gauge of the same embodiment.

[0025] Figure 4 is a cross-sectional view showing a state where a sensor module is detached from the vacuum gauge of the same embodiment.

[0026] Figure 5 is a cross-sectional view showing a main connector of the vacuum gauge of the same embodiment.

[0027] Figure 6 is a functional block diagram showing functions of the vacuum gauge of the same embodiment.

[0028] Figure 7 is a cross-sectional view of the main connector of the same embodiment.

[0029] BRIEF DESCRIPTION OF DRAWINGS

[0030] 100 vacuum gauge

[0031] 1 sensor module

[0032] 11 introduction space

[0033] 12 diaphragm

[0034] 13 detection electrode

[0035] 14 output electrode

[0036] 15 housing

[0037] 16 heater

[0038] 17 heat insulator

[0039] 2 main body module

[0040] 22 Calibration Data Storage Unit

[0041] 23 Pressure Calculation Department

[0042] 24. Correction coefficient storage unit

[0043] 25. Revision Section

[0044] PB pressure calculation circuit

[0045] CB heater control circuit

[0046] 3. Thermal insulation module

[0047] 31 Thermal insulation components

[0048] 32. Center conductor

[0049] 33 Insulators

[0050] 34. External conductor

[0051] 35 Connector Socket

[0052] 36 Contact spring

[0053] MC Main Connector Detailed Implementation

[0054] Reference Figures 1 to 7 This invention describes a vacuum gauge 100 according to one embodiment of the present invention.

[0055] The vacuum gauge 100 of this embodiment is used, for example, to monitor the vacuum level in a measurement space, i.e., a vacuum chamber, where film deposition is performed in semiconductor processing. The vacuum gauge 100 is disposed on the outside of the partition wall of the vacuum chamber and connected to the interior of the vacuum chamber in a manner that allows communication with the interior of the vacuum chamber.

[0056] like Figure 1 As shown, the vacuum gauge 100 is roughly rectangular in shape, with a vacuum connector VC at its front end and an output terminal T at its base end for outputting the measured pressure value to the outside.

[0057] like Figure 2 As shown in the cross-sectional view, the vacuum gauge 100 houses or forms three modules within the housing C. Specifically, the three modules include: a sensor module 1, housed at the front end of the housing C and in communication with the atmosphere inside the vacuum chamber; a main body module 2, formed at the base of the housing C, housing circuitry for processing output signals from the sensor module 1 or controlling the sensor module 1; and a heat insulation module 3, located in the middle portion of the housing C and formed between the sensor module 1 and the main body module 2, preventing heat emitted by the sensor module 1 from being transferred to the main body module 2.

[0058] In the vacuum gauge 100 of the present embodiment, the sensor module 1 is detachable with respect to the main module 2 and the heat insulation module 3. Specifically, as shown in Figure 3 the cross-sectional view, the cover Cl constituting one side surface of the housing C is slidable with respect to the longitudinal direction of the housing C, and as shown in Figure 4 the cross-sectional view, the sensor module 1 can be detached from the inside of the housing C by releasing the connection between the sensor module 1 and the main module 2. Further, the sensor module 1 can be installed to the main module 2 by housing the sensor module 1 in the state of opening the housing C. As shown in Figure 2 the cross-sectional view, the position of the main module 2 inside the housing C can be fixed by pressing and fixing the side surface of the main module 2 from the housing C using a fixing member F such as a screw. Further, the sensor module 1 can be detached from the inside of the housing C by detaching the fixing member F. Further, the upper surface side of the sensor module 1 and the main module 2 are connected by the detachable main connector MC provided in the heat insulation module 3.

[0059] Each module will be described in detail below.

[0060] As shown in Figure 2 and Figure 5 the enlarged cross-sectional view, the sensor module 1 includes a vacuum connector VC installed to the vacuum chamber, a sensing mechanism S exposed to the atmosphere inside the vacuum chamber in part, and a heater 16 provided around the sensing mechanism S.

[0061] The sensing mechanism S is a diaphragm type pressure detection mechanism of a capacitance type, which includes an introduction space 11 into which the atmosphere is introduced from the vacuum connector VC into the vacuum chamber, a diaphragm 12 that separates the introduction space 11 from the reference pressure side such as the atmospheric pressure, a detection electrode 13 provided opposite to the central portion of the diaphragm 12, and an output electrode 14 that outputs the potential of the detection electrode 13 as an output signal to the main module 2.

[0062] The diaphragm 12 is a thin film circular plate, and the outer peripheral portion thereof is clamped and supported by a clamping member. If the pressure inside the vacuum chamber changes, the diaphragm 12 is deformed due to the pressure difference between both surfaces thereof. The component of the material gas introduced into the vacuum chamber also flows to the introduction space 11 side of the diaphragm 12, and there is a possibility that the gas adheres, condenses, and accumulates.

[0063] A slight gap is formed between the detection electrode 13 and the diaphragm 12, and the separation distance between the detection surface of the detection electrode 13 and the central portion of the diaphragm 12 changes due to the deformation of the diaphragm 12. The detection electrode 13 detects the change in the capacitance due to the change in the separation distance as a change in the potential.

[0064] The sensing mechanism S is housed in a generally cubical metal housing 15, and a heater 16 is disposed on the outer surface of the housing 15. Specifically, the heater 16 is, for example, a film heater 16, wound in a thin-walled cylindrical shape around the housing 15, and its set temperature can be varied according to the applied voltage or current. Figure 5 As shown, the heater 16 is configured to extend from the diaphragm 12 towards the front end and the base end, primarily for maintaining the temperature of the diaphragm 12 at a desired temperature. Furthermore, a heat insulation member 17 for heat insulation is provided on the outer periphery of the heater 16.

[0065] In this embodiment, the sensing mechanism S and the heater 16 are integrated to form the sensor module 1. When the sensing mechanism S accumulates and needs to be replaced, the heater 16 is also replaced at the same time.

[0066] The main module 2 includes: a pressure calculation circuit PB, which calculates the pressure value based on the output signal of the sensing mechanism S; and a heater control circuit CB, which is responsible for powering and controlling the heater 16.

[0067] The pressure calculation circuit PB and the heater control circuit CB are so-called microcomputers equipped with input / output means such as CPU, memory, A / D converter, and D / A converter. They execute programs stored in memory and achieve their functions through the cooperation of various devices.

[0068] like Figure 6 As shown, the pressure calculation circuit PB functions as at least the calibration data storage unit 22, the pressure calculation unit 23, the correction coefficient storage unit 24, and the correction unit 25.

[0069] The calibration data storage unit 22 stores calibration data representing the characteristics of the currently connected sensing mechanism S. The calibration data is, for example, a calibration curve showing the relationship between the voltage value and the pressure value represented by the output signal of the sensing mechanism S. This calibration data can be rewritten via external input. That is, when the sensor module 1 is replaced, the pressure calculation circuit PB can calculate an accurate pressure value by rewriting the individual calibration data corresponding to the sensor module 1. The calibration data can be generated by calibration in a vacuum chamber equipped with the vacuum gauge 100, but it is preferable to perform the calibration at the manufacturer's facility during pre-shipment inspection of the sensor module 1, and provide the calibration data obtained at that time along with the sensor module 1. By doing so, even without calibration when replacing the sensor module 1, an accurate pressure can be obtained immediately simply by overwriting the calibration data storage unit 22 with the calibration data corresponding to the new sensor module 1.

[0070] The pressure calculation unit 23 calculates the pressure value based on the voltage value represented by the output signal from the sensing mechanism S and the calibration data stored in the calibration data storage unit 22.

[0071] The correction coefficient storage unit 24 stores correction coefficients corresponding to the set temperature of the heater 16. That is, the correction coefficient is a coefficient used to output the correct pressure value in response to changes in the amount of deformation caused by the temperature of the diaphragm 12. For example, the correction coefficient storage unit 24 stores the correction coefficients corresponding to each set temperature in a table format.

[0072] The correction unit 25 corrects the pressure value calculated by the pressure calculation unit 23 according to the correction coefficient. Specifically, the correction unit 25 reads the correction coefficient corresponding to the set temperature set for the heater 16 from the correction coefficient storage unit 24. Furthermore, the correction unit 25 multiplies the pressure value output from the pressure calculation circuit PB by the read correction coefficient to calculate the corrected pressure value.

[0073] The heater control circuit CB receives a set temperature from an external input, such as from a user, and performs feedback control on the voltage or current value applied to the heater 16 in a manner that corresponds to the set temperature. In this embodiment, the range of the set temperature received by the heater 16 control unit is set to 100°C to 300°C. This range corresponds to the condensation temperature of the material gas that may be introduced into the vacuum chamber. That is, the user can select an appropriate temperature that does not produce condensation and decomposition, based on the type of material gas introduced into the vacuum chamber, and set that temperature as the set temperature. Furthermore, the heater control circuit CB performs temperature feedback control, for example, by minimizing the deviation between the measured temperature of a temperature sensor, such as a thermistor installed in the sensor module 1, and the set temperature, thereby controlling the current or voltage applied to the heater 16.

[0074] Finally, the thermal insulation module 3 will be explained. For example... Figure 2 As shown, the heat insulation module 3 separates the sensor module 1 and the main body module 2 by a predetermined distance and has space for heat insulation. In the heat insulation module 3, a heat insulation element 31 is also provided at the boundary between the sensor module 1 and the main body module 2, making it difficult for heat emitted by the heater 16 in the sensor module 1 to be transferred to the main body module 2. The separation distance between the sensor module 1 and the heat insulation module 3 is set such that even when, for example, the heater 16 is set to the highest set temperature, the temperature of the main body module 2 will not rise to a temperature that would cause malfunctions or failures in the pressure calculation circuit PB and the heater control circuit CB within the main body module 2 due to heat from the heater 16.

[0075] Since the heat insulation module 3 is provided, the sensor module 1 and the main body module 2 are separated. Therefore, in order to transmit and receive signals and supply power, multiple connectors connecting the sensor module 1 and the main body module 2 are provided in the heat insulation module 3.

[0076] Specifically, it includes: a main connector MC, located in the center of the heat insulation module 3, connecting the sensing mechanism S and the pressure calculation circuit PB; and a secondary connector, connecting the heater 16 and the heater control circuit CB (not shown).

[0077] like Figure 7 As shown in the enlarged view, the main connector MC includes: a center conductor 32 for transmitting the output signal of the sensing mechanism S; an electrically insulating cylindrical insulator 33 covering the side circumferential surface of the center conductor 32; and an outer conductor 34 covering the outer circumferential surface of the insulator 33. Furthermore, contact springs 36 are provided at each end of the main connector MC, which press radially when the output electrode 14 of the sensing mechanism S or the input terminal 21 of the pressure calculation circuit PB is inserted. Additionally, the ends of the main connector MC engage with cylindrical shields covering the output electrode 14 of the sensing mechanism S and the input terminal of the pressure calculation circuit PB, respectively, where contact springs 36 also press radially inward. The contact springs 36 generate resistance when the output electrode 14 and input terminal 21 are fully inserted, thus allowing confirmation, even without visual inspection, that the pressure calculation circuit PB of the main module 2 is fully connected via the main connector MC when replacing the sensor module 1.

[0078] Furthermore, the heat insulation module 3 is equipped with a cylindrical conductive connector socket 35 that covers the main connector MC. The connector socket 35 is fixed within the heat insulation module 3 and grounded to a ground potential. That is, the center conductor 32 of the main connector MC is doubly shielded by the outer conductor 34 and the connector socket 35. Therefore, even if the sensing mechanism S and the pressure calculation circuit PB are separated, noise is unlikely to be superimposed on the output signal of the sensing mechanism S, thereby making it easy to obtain accurate pressure values.

[0079] The secondary connector, unlike the main connector MC, uses a flexible wire to connect the heater 16 and the heater control circuit CB. This allows for easy connection between the sensor module 1 and the main module 2, even without strict control over the positional accuracy of each terminal.

[0080] According to the vacuum gauge 100 of the present embodiment thus configured, since the set temperature of the heater 16 that temperature-regulates the sensing mechanism S is variable, the sensing mechanism S can be temperature-regulated at a temperature corresponding to each material gas in the vacuum chamber. Therefore, the sensing mechanism S can be temperature-regulated at the most suitable temperature according to the condensation temperature and the decomposition temperature of the material gas, and the deposition of the components on the diaphragm 12 of the sensing mechanism S due to the condensation of the material gas can be prevented without affecting the film formation in the vacuum chamber and the like.

[0081] Therefore, even in a case where a material gas that has not been used in the past is used along with the miniaturization of semiconductor processing, the long life of the sensing mechanism S and the reduction in the frequency of occurrence of the downtime can be achieved, and thus the productivity can be improved.

[0082] Further, even in a case where the components are gradually deposited on the sensing mechanism S little by little and eventually reach the life span, the main body module 2 can be left as it is and only the sensor module 1 can be replaced as a consumable, and the measurement of the pressure can be immediately started again. At this time, by overwriting the calibration data storage section 22 with the corresponding calibration data together with the replacement of the sensor module 1, the calibration work at the time of replacement can be omitted.

[0083] Therefore, compared to the conventional technology, the time required from the replacement of the sensor module 1 to the start of the measurement of the pressure again can be greatly shortened, and the length of the downtime itself can be shortened.

[0084] Other embodiments will be described below.

[0085] In the above-described embodiment, the thermal insulation module is provided so as to separate the sensor module and the main body module by a prescribed distance, but for example, the thermal insulation module can be omitted as long as the heat emitted from the sensor module can be sufficiently blocked from being transmitted to the main body module. That is, the sensor module and the main body module can be provided adjacent to each other.

[0086] The sensor module is detachable with respect to the main body module, but for example, in a case where the sensor module hardly needs to be replaced by the heating of the heater, the main body module and the sensor module can be integrated and cannot be separated. In this case, as long as at least the set temperature of the heater is variable, it is acceptable.

[0087] The sensing mechanism is not limited to the diaphragm type pressure detection mechanism. For example, it can be an ionization type pressure detection mechanism, or a mechanism that detects the pressure based on the relationship between the number of vibrations of the structure and the pressure.

[0088] The measurement space of the vacuum gauge is not limited to the vacuum chamber in which the film formation is performed, and other spaces can be used as the measurement space.

[0089] Moreover, various modifications can be made and combinations of part features can be made without departing from the inventive idea of the present application.

Claims

1. A vacuum gauge characterized by comprising: a sensing mechanism which is in contact with an atmosphere in a measurement space and outputs an output signal corresponding to a pressure in the measurement space; and a heater which temperature-regulates the sensing mechanism, a set temperature of the heater is variable.

2. The vacuum gauge according to claim 1, characterized by comprising: a sensor module which has the sensing mechanism; and a main body module which has: a pressure calculation circuit which inputs the output signal of the sensing mechanism and calculates a pressure value; and a heater control circuit which controls a temperature of the heater, the heater control circuit controls a current or a voltage of the heater in such a manner that the temperature of the heater becomes a set temperature which is inputted. the sensor module is detachable with respect to the main body module.

4. The vacuum gauge according to claim 3, characterized by comprising:

3. The gauge of claim 1, wherein, the pressure calculation circuit includes: a calibration data storage section which stores calibration data corresponding to the sensing mechanism; and a pressure calculation section which calculates a pressure value based on the output signal of the sensing mechanism and the calibration data, the calibration data storage section is capable of updating the calibration data by external input.

5. The vacuum gauge according to claim 4, characterized by comprising: the pressure calculation circuit further includes: a correction coefficient storage section which stores a correction coefficient corresponding to the set temperature of the heater; and a correction section which corrects the pressure value calculated by the pressure calculation section based on the correction coefficient. the vacuum gauge further includes a heat insulation module which separates the sensor module and the main body module by a prescribed distance and hinders the transfer of heat generated by the sensor module to the main body module.

7. The vacuum gauge according to claim 2, characterized by comprising:

6. The gauge of claim 2, wherein, the sensor module further has the heater, the sensing mechanism of the sensor module is integrated with the heater, and the sensor module is detachable with respect to the main body module.

8. The vacuum gauge according to claim 6, characterized by comprising: the heat insulation module is provided with: a main connector which connects between the sensing mechanism and the pressure calculation circuit; and a sub connector which connects between the heater and the heater control circuit, at least one of the main connector and the sub connector has flexibility.

9. The vacuum gauge according to claim 8, characterized by comprising: the main connector includes: a center conductor which transmits the output signal of the sensing mechanism; an electrically-insulating cylindrical insulator which covers a side peripheral surface of the center conductor; and an outer conductor which covers an outer peripheral surface of the insulator, the heat insulation module is provided with a connector socket of a cylindrical conductor system which covers an outer side of the outer conductor. ​ ​

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