JP7704565B2 - diaphragm vacuum gauge - Google Patents

Description

The present invention relates to a diaphragm vacuum gauge.

Diaphragm vacuum gauges are used to measure the pressure in semiconductor process chambers. If the temperature of the semiconductor process gas is not appropriate, it will liquefy or solidify and adhere to the sensor part of the diaphragm vacuum gauge, affecting the measurement. For this reason, diaphragm vacuum gauges have a self-heating function to prevent adhesion of liquefied or solidified process gas (see Patent Documents 1, 2, and 3).

On the other hand, semiconductor processes have become more sophisticated in recent years, and a variety of gases are used in a single process. Since the appropriate self-heating temperature may differ depending on the process gas, some diaphragm vacuum gauges have a function for switching the self-heating temperature, such as the diaphragm vacuum gauges disclosed in Patent Documents 2 and 3. Furthermore, some diaphragm vacuum gauges are equipped with a function for turning off the self-heating function to reduce power consumption when the diaphragm vacuum gauge is not in use.

However, conventional diaphragm vacuum gauges had the problem that a switching signal had to be input from outside to the diaphragm vacuum gauge in order to switch the self-heating temperature.

JP 2010-117154 A JP 2009-243887 A JP 2019-7906 A

The present invention has been made to solve the above problems, and aims to provide a diaphragm vacuum gauge that can automatically switch the self-heating temperature.

The diaphragm vacuum gauge of the present invention comprises a pressure receiving section configured to change electrical characteristics in response to displacement of a diaphragm due to pressure of a medium to be measured, a heater configured to heat the pressure receiving section, a temperature sensor configured to measure the temperature of the pressure receiving section, a pressure measuring section configured to convert the change in electrical characteristics of the pressure receiving section into a measured pressure value, a temperature setting section configured to set a heating temperature set value in response to the measured pressure value obtained by the pressure measuring section, a heater control section configured to control the power supplied to the heater based on the temperature measured by the temperature sensor and the heating temperature set value , and a memory section configured to store the measured pressure value and the heating temperature set value in association with each other, wherein the temperature setting section obtains from the memory section the heating temperature set value corresponding to the measured pressure value obtained by the pressure measuring section.

In one configuration example of the diaphragm vacuum gauge of the present invention, the memory unit further stores an automatic setting disable flag for when the pressure increases and an automatic setting disable flag for when the pressure decreases, and the temperature setting unit disables switching of the heating temperature set value when the measured pressure value increases when the flag for when the pressure decreases is set, and disables switching of the heating temperature set value when the measured pressure value decreases.
In one configuration example of the diaphragm vacuum gauge of the present invention, the memory unit further stores a delay time until the heating temperature set value is switched, and the temperature setting unit, when switching the heating temperature set value, switches the heating temperature set value after the delay time has elapsed.
Furthermore, in one configuration example of the diaphragm vacuum gauge of the present invention, the memory unit stores a pressure rise delay time and a pressure fall delay time as the delay time, and the temperature setting unit, when switching the heating temperature set value when the measured pressure value is rising, switches the heating temperature set value after the pressure rise delay time has elapsed, and, when switching the heating temperature set value when the measured pressure value is falling, switches the heating temperature set value after the pressure fall delay time has elapsed.

Moreover, one configuration example of the diaphragm vacuum gauge of the present invention is characterized in that it further comprises a setting change section capable of changing the stored contents of the storage section in response to an external instruction.
Moreover, one configuration example of the diaphragm vacuum gauge of the present invention is characterized in that it further comprises a notification section configured to notify the outside of the heating temperature set value.
In addition, one configuration example of the diaphragm vacuum gauge of the present invention is characterized in that it further comprises a notification unit configured to notify an outside party that the self-heating temperature of the diaphragm vacuum gauge has reached the heating temperature set value when the temperature measured by the temperature sensor reaches the heating temperature set value.

According to the present invention, by providing a temperature setting unit that sets the heating temperature setting value according to the measured pressure value, the self-heating temperature of the diaphragm vacuum gauge can be automatically switched, and since an external signal for switching the self-heating temperature is not required, there is no need to create hardware for generating a switching signal for the self-heating temperature.

FIG. 1 is a block diagram showing the configuration of a diaphragm vacuum gauge according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of a main part of a sensor chip of a diaphragm vacuum gauge according to an embodiment of the present invention. FIG. 3 is a flow chart illustrating the operation of the diaphragm vacuum gauge according to the embodiment of the present invention. FIG. 4 is a diagram showing an example of parameters stored in the memory unit of the diaphragm vacuum gauge according to the embodiment of the present invention. FIG. 5 is a diagram showing an example of the self-heating temperature switching operation of the diaphragm vacuum gauge according to the embodiment of the present invention. FIG. 6 is a block diagram showing an example of the configuration of a computer that realizes the circuit section of the diaphragm vacuum gauge according to the embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. Figure 1 is a block diagram showing the configuration of a diaphragm vacuum gauge according to an embodiment of the present invention, and Figure 2 is a diagram showing the configuration of the main parts of a sensor chip used in the diaphragm vacuum gauge.

The diaphragm vacuum gauge has a pressure receiving section 10 whose capacitance (electrical characteristic) changes in response to the displacement of a diaphragm (membrane) caused by the pressure of the medium being measured (e.g., process gas), and a circuit section 11 that converts the change in capacitance of the pressure receiving section 10 into a measured pressure value.

The sensor chip 1 of the pressure receiving section 10 comprises a diaphragm component 100 and a base 101. The diaphragm component 100 comprises a diaphragm 102 configured to be deformable in response to the pressure P of the medium to be measured (e.g., process gas), and a diaphragm support section 103 formed to be thicker than the diaphragm 102 and supporting the peripheral portion of the diaphragm 102 so that it cannot be displaced. The base 101 is joined to the diaphragm support section 103, and together with the diaphragm 102, forms a reference vacuum chamber 104.

In the sensor chip 1, a fixed electrode 105 is formed on the surface of the base 101 facing the reference vacuum chamber 104, and a movable electrode 106 is formed on the surface of the diaphragm 102 facing the reference vacuum chamber 104 so as to face the fixed electrode 105. When the diaphragm 102 is deflected by the pressure P of the medium to be measured, the distance between the movable electrode 106 and the fixed electrode 105 changes, and the electrostatic capacitance between the movable electrode 106 and the fixed electrode 105 changes. The pressure P of the medium to be measured received by the diaphragm 102 can be detected from this change in electrostatic capacitance. The diaphragm component 100 and the base 101 are made of an insulator such as sapphire.

The diaphragm vacuum gauge shown in FIG. 1 comprises a sensor chip 1 configured as described above, a housing 2 that contains the sensor chip 1, a pressure introduction tube 3 that introduces the pressure P of the medium to be measured to the diaphragm 102 of the sensor chip 1, a sensor case 4 that covers the housing 2, and a heater 5 that is provided to surround the outer periphery of the sensor case 4. The sensor case 4 with the heater 5 provided therein is covered with a heat insulating material 6.

A partition wall 7 is provided inside the housing 2. The partition wall 7 is composed of a base plate 7a and a support plate 7b, and separates the internal space of the housing 2 into a first space 2a and a second space 2b. The outer periphery of the support plate 7b is fixed to the housing 2, and supports the base plate 7a in a floating state within the internal space of the housing 2. The sensor chip 1 is fixed to the second space 2b side of the base plate 7a. The base plate 7a is also formed with a pressure introduction hole 7c that introduces the pressure in the first space 2a to the diaphragm 102 of the sensor chip 1. The second space 2b is connected to the reference vacuum chamber 104 of the sensor chip 1 and is in a vacuum state.

The pressure introduction pipe 3 is connected to the first space 2a side of the housing 2. A baffle 8 is provided between the pressure introduction pipe 3 and the housing 2. The medium to be measured introduced through the pressure introduction pipe 3 hits the plate surface of the baffle 8 and flows into the first space 2a of the housing 2 through the gap around the baffle 8.
A temperature sensor 9 is provided on the outer wall surface of the housing 2. The temperature sensor 9 measures the temperature of the housing 2 as the temperature of the pressure receiving portion 10.

The circuit section 11 of the diaphragm vacuum gauge is composed of a capacitance detection section 12, a pressure measurement section 13, a temperature setting section 14, a memory section 15, a heater control section 16, a notification section 17, and a setting change section 18.

Next, the operation of the present embodiment will be described with reference to the flowchart of FIG.
The capacitance detection unit 12 detects a change in electrostatic capacitance (electrical characteristic) between the movable electrode 106 and the fixed electrode 105 due to the displacement of the diaphragm 102 of the pressure receiving unit 10 (step S100 in FIG. 3).

The pressure measuring unit 13 converts the change in capacitance detected by the capacitance detecting unit 12 into a measured pressure value MP and outputs it (step S101 in FIG. 3).
The temperature setting unit 14 sets the heating temperature setting value tsp in accordance with the measured pressure value MP obtained by the pressure measuring unit 13 (Step S102 in FIG. 3).

The memory unit 15 stores the measured pressure value MP and the heating temperature set value tsp in association with each other. The temperature setting unit 14 acquires the heating temperature set value tsp corresponding to the measured pressure value MP from the memory unit 15. The parameter consisting of the pair of the measured pressure value MP and the corresponding heating temperature set value tsp can be freely changed by the user from outside the diaphragm vacuum gauge.

The temperature detection unit 19 acquires the value of the temperature tpv measured by the temperature sensor 9. The heater control unit 16 controls the power supplied to the heater 5 so that the temperature tpv measured by the temperature sensor 9 coincides with the heating temperature setting value tsp (step S103 in FIG. 3).
The notification unit 17 notifies the heating temperature set value tsp of the diaphragm vacuum gauge to the outside, that is, to the user, by displaying the current heating temperature set value tsp (step S104 in FIG. 3).

When the temperature tpv measured by the temperature sensor 9 reaches the heating temperature set value tsp (YES in step S105 in FIG. 3), the notification unit 17 notifies the user that the self-heating temperature of the diaphragm vacuum gauge has reached the heating temperature set value tsp, for example by displaying a message indicating that the self-heating temperature has reached the heating temperature set value tsp or by lighting an LED or the like (step S106 in FIG. 3).

The diaphragm vacuum gauge repeats steps S100 to S106 at regular intervals until the pressure measurement operation is terminated by an external command, such as a user command (YES in step S107 in Figure 3).

In this way, in this embodiment, the self-heating temperature of the diaphragm vacuum gauge can be automatically switched, eliminating the need for an external signal to switch the self-heating temperature.

When the temperature setting unit 14 switches the heating temperature set value tsp because the measured pressure value MP exceeds a certain range, the temperature setting unit 14 may provide a delay time before switching the heating temperature set value tsp so that the heating temperature set value tsp is not switched immediately. This delay time can also be registered in advance as a parameter in the memory unit 15.

The delay time may be set to be ineffective when the measured pressure value MP is rising, but effective only when the measured pressure value MP is falling. That is, the delay time may be set to a pressure rise delay time and a pressure fall delay time.
When the pressure rise delay time is set, the temperature setting unit 14 switches the heating temperature set value tsp when the measured pressure value MP rises, after the pressure rise delay time has elapsed. When the pressure fall delay time is set, the temperature setting unit 14 switches the heating temperature set value tsp when the measured pressure value MP falls, after the pressure fall delay time has elapsed.

In addition, the memory unit 15 can pre-register in advance a flag for disabling the automatic setting of the heating temperature set value tsp when the measured pressure value MP increases, and a flag for disabling the automatic setting of the heating temperature set value tsp when the measured pressure value MP decreases, as parameters.
When the pressure rise automatic setting disable flag is set, the temperature setting unit 14 disables switching of the heating temperature set value tsp when the measured pressure value MP rises. Also, when the pressure fall automatic setting disable flag is set, the temperature setting unit 14 disables switching of the heating temperature set value tsp when the measured pressure value MP falls.

The setting change unit 18 can change the parameters stored in the memory unit 15 from the outside, i.e., in response to instructions from the user.

FIG. 4 is a diagram showing an example of parameters stored in the storage unit 15, and FIG. 5 is a diagram showing an example of the self-heating temperature switching operation.
As shown in FIG. 4, the memory unit 15 stores, as parameters, the range of the measured pressure value MP, the heating temperature set value tsp, the delay time during pressure increase, the delay time during pressure decrease, an automatic setting disable flag during pressure increase, and an automatic setting disable flag during pressure decrease.

In the example of FIG. 4, since the pressure rise delay time is not set, when the heating temperature set value tsp is switched when the measured pressure value MP rises, the switching occurs immediately. On the other hand, since the pressure fall delay time Tdown is set, when the heating temperature set value tsp is switched when the measured pressure value MP falls, the switching occurs after waiting for Tdown. Since the pressure rise automatic setting disable flag and the pressure fall automatic setting disable flag are both set to "RESET", the heating temperature set value tsp is automatically set when the measured pressure value MP rises and falls. To disable the automatic setting, simply set the disable flag to "SET".

In addition, in the ranges of MP<SP1 and SP3≦MP, the heating temperature set value tsp is “OFF.” When it is “OFF,” the heater control unit 16 does not supply power to the heater 5.
In order to make the state transitions in FIG. 5 easier to understand, the process states are shown in FIG. 4, but the process states in FIG.

Next, the self-heating temperature switching operation based on the settings in Fig. 4 will be described with reference to Fig. 5. The example in Fig. 5 shows an example in which the diaphragm vacuum gauge of this embodiment is used to measure the pressure in a semiconductor process chamber.
First, an inert gas such as _N2 is introduced into the process chamber in a vacuum state, and the measured pressure value MP increases. When the measured pressure value MP is less than the set value SP1, the temperature setting unit 14 sets the heating temperature set value tsp to "OFF". Therefore, the heater control unit 16 does not supply power to the heater 5.

When the measured pressure value MP rises further and exceeds the set value SP1, the temperature setting unit 14 sets the heating temperature set value tsp to 200°C. Since no pressure rise delay time is set here, the heating temperature set value tsp is switched immediately. The heater control unit 16 then controls the power supplied to the heater 5 so that the temperature tpv measured by the temperature sensor 9 matches the heating temperature set value tsp = 200°C.

Next, process gas A is introduced into the process chamber. After the film formation process using process gas A, an inert gas such as _N2 is introduced into the process chamber, and the measured pressure value MP further increases. When the measured pressure value MP becomes equal to or greater than the set value SP2 (SP1<SP2), the temperature setting unit 14 sets the heating temperature set value tsp to 50°C. As in the above, since no pressure rise delay time is set, the heating temperature set value tsp is switched immediately. Then, the heater control unit 16 controls the power supplied to the heater 5 so that the temperature tpv measured by the temperature sensor 9 coincides with the heating temperature set value tsp=50°C.

Next, process gas B is introduced into the process chamber. After the film formation process using process gas B, an inert gas such as _N2 is introduced into the process chamber, and the measured pressure value MP further increases. When the measured pressure value MP becomes equal to or greater than the set value SP3 (SP2<SP3), the temperature setting unit 14 sets the heating temperature set value tsp to "OFF". As in the above, since no pressure rise delay time is set, the heating temperature set value tsp is switched immediately. Then, the heater control unit 16 does not supply power to the heater 5 because the heating temperature set value tsp has become "OFF".

Next, the process chamber begins to be evacuated, and the measured pressure value MP drops. At this time, because the pressure drop delay time Tdown has been set, the heating temperature set value tsp remains "OFF". In other words, when the measured pressure value MP falls below the set value SP3, the heating temperature set value tsp should be switched to 50°C, but the measured pressure value MP falls below the set value SP2 before the pressure drop delay time Tdown has elapsed. When the measured pressure value MP falls below the set value SP2, the heating temperature set value tsp should be switched to 200°C, but the measured pressure value MP falls below the set value SP1 before the pressure drop delay time Tdown has elapsed. Therefore, in either case, the heating temperature set value tsp is not switched.

In this way, in this embodiment, it is possible to set the optimal heating temperature set value tsp to match the process gas. In addition, when self-heating is not required, power supply to the heater 5 is stopped, thereby reducing power consumption.

In this embodiment, a capacitance type diaphragm vacuum gauge in which the capacitance changes in response to the displacement of the diaphragm has been described, but the present invention is not limited to this and may be applied to other types of diaphragm vacuum gauges. An example of a diaphragm vacuum gauge of another type is a piezo-resistance type diaphragm vacuum gauge that uses semiconductor silicon with a diffused resistor as the diaphragm and converts the change in resistance of the resistor in response to the displacement of the diaphragm into a measured pressure value.

The circuit unit 11 described in this embodiment can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Figure 6.

The computer includes a CPU 200, a storage device 201, and an interface device (I/F) 202. The I/F 202 is connected to the hardware portion of the capacitance detection unit 12, the hardware portion of the heater control unit 16, the hardware portion of the notification unit 17, the hardware portion of the setting change unit 18, and the like. In such a computer, a program for implementing the method of the present invention is stored in the storage device 201. The CPU 200 executes the processing described in this embodiment according to the program stored in the storage device 201.

The present invention can be applied to diaphragm vacuum gauges.

1...sensor chip, 5...heater, 9...temperature sensor, 10...pressure receiving section, 11...circuit section, 12...capacitance detection section, 13...pressure measurement section, 14...temperature setting section, 15...storage section, 16...heater control section, 17...notification section, 18...setting change section, 19...temperature detection section, 102...diaphragm, 105...fixed electrode, 106...movable electrode.

Claims (7)

a pressure receiving section configured such that an electrical characteristic changes in response to a displacement of a diaphragm caused by a pressure of a medium to be measured;
A heater configured to heat the pressure receiving portion;
A temperature sensor configured to measure a temperature of the pressure receiving portion;
a pressure measuring unit configured to convert a change in an electrical characteristic of the pressure receiving unit into a measured pressure value;
a temperature setting unit configured to set a heating temperature setting value in accordance with the measured pressure value obtained by the pressure measuring unit;
a heater control unit configured to control power supplied to the heater based on the temperature measured by the temperature sensor and the heating temperature setting value ;
a storage unit configured to store the measured pressure value and the heating temperature set value in association with each other ,
The diaphragm vacuum gauge according to claim 1, wherein the temperature setting unit obtains from the memory unit a heating temperature setting value corresponding to a measured pressure value obtained by the pressure measuring unit . 2. The diaphragm vacuum gauge according to claim 1 ,
The storage unit further stores an automatic setting invalidation flag when a pressure increases and an automatic setting invalidation flag when a pressure decreases,
the temperature setting unit disables switching of the heating temperature set value when the measured pressure value increases when the pressure increase automatic setting disable flag is set, and disables switching of the heating temperature set value when the measured pressure value decreases when the pressure decrease automatic setting disable flag is set. 3. The diaphragm vacuum gauge according to claim 1 ,
The storage unit further stores a delay time until the heating temperature setting value is switched,
The diaphragm vacuum gauge, wherein the temperature setting unit switches the heating temperature set value after the delay time has elapsed when switching the heating temperature set value. 4. The diaphragm vacuum gauge according to claim 3 ,
The storage unit stores a pressure increase delay time and a pressure decrease delay time as the delay time,
the temperature setting unit switches the heating temperature set value after the pressure rise delay time has elapsed when switching the heating temperature set value when the measured pressure value is increasing, and switches the heating temperature set value after the pressure fall delay time has elapsed when switching the heating temperature set value when the measured pressure value is decreasing. 5. The diaphragm vacuum gauge according to claim 1 ,
4. The diaphragm vacuum gauge according to claim 1, further comprising a setting change unit capable of changing the contents stored in the memory unit in response to an external instruction. 6. The diaphragm vacuum gauge according to claim 1 ,
The diaphragm vacuum gauge further comprises a notification unit configured to notify an outside of the heating temperature setting value. 6. The diaphragm vacuum gauge according to claim 1 ,
a notification unit configured to notify an outside source that the self-heating temperature of the diaphragm vacuum gauge has reached a heating temperature set value when the temperature measured by the temperature sensor reaches the heating temperature set value.

Images