JP4994058B2 - Pressure measuring device and pressure measuring method - Google Patents

Description

  The present invention relates to a pressure measuring device and a pressure measuring method.

A Pirani gauge is widely known that includes a filament (electric resistor) made of a thin metal wire and measures the gas pressure from the amount of heat loss of the filament due to heat exchange between the filament and the gas. The Pirani gauge outputs an electrical signal corresponding to the heat loss of the filament. The pressure of the gas is obtained using a conversion table that converts the output signal into pressure.
JP-A-7-120339

  However, the output signal of the Pirani gauge is shifted with changes in the ambient temperature and resistivity of the filament even if the pressure of the gas to be measured is constant. In this case, there is a problem that it is difficult to accurately obtain the gas pressure using the conversion table.

If a diaphragm vacuum gauge or a piezo vacuum gauge is employed instead of the Pirani vacuum gauge, the output signal does not change even if the ambient temperature or resistivity of the filament changes. However, while the Pirani vacuum gauge has a wide pressure measurable range of 10 ⁻² to 10 ⁵ Pa, the pressure measurable range of one diaphragm vacuum gauge or piezoresistive pressure gauge is as narrow as about 3 to 4 digits. For this reason, it is necessary to use a plurality of diaphragm gauges or the like having different pressure measurable ranges, which increases the manufacturing cost.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a pressure measuring device and a pressure measuring method capable of accurately obtaining a gas pressure.

In order to achieve the above object, a pressure measuring device according to the present invention includes a first pressure gauge that outputs an electrical signal corresponding to a gas pressure, and a conversion formula for obtaining the gas pressure from the output of the first pressure gauge. An arithmetic device for calculation; and a second pressure gauge that is arranged in proximity to the first pressure gauge and measures the pressure of the gas, wherein the second pressure gauge is narrower than a pressure measurement range of the first pressure gauge. The gas pressure is measured in a range, and the arithmetic unit uses the gas pressure measurement result by the second pressure gauge to apply the conversion formula applied to a range wider than the pressure measurement range of the second pressure gauge. a pressure measuring device for calculating a first pressure gauge is a Pirani gauge, characterized in that said second pressure gauge is septa film gauge or piezoresistive pressure gauge.
According to this configuration, even when the output of the first pressure gauge is shifted, the pressure of the gas is measured with the second pressure gauge arranged close to the first pressure gauge, and the conversion formula is calculated using the pressure measurement result. Thus, the gas pressure can be accurately obtained from the output of the first pressure gauge. At this time, it is sufficient to employ a second pressure gauge having a pressure measurement range narrower than that of the first pressure gauge, so that the manufacturing cost can be reduced.

The first pressure gauge is a Pirani vacuum gauge that includes an electrical resistor that exchanges heat with gas and outputs an electrical signal corresponding to the amount of heat loss of the electrical resistor, and measures the pressure of the first pressure gauge. The range is preferably 10 ⁻² Pa or more and 10 ⁵ Pa or less, and the pressure measurement range of the second pressure gauge is desirably 50 Pa or more and 10 ⁵ Pa or less.
The output of the Pirani gauge has the characteristic (inflection point) in ¹⁰ 3 Pa or less in the range of 50 Pa. Therefore, it is desirable to set the pressure measurement range of the second pressure gauge within the range of 50 Pa to 10 ⁵ Pa including the above range. By calculating the conversion formula using the pressure measurement result of the second pressure gauge in the range, the gas pressure is measured from the output of the Pirani gauge in the range of 1 Pa to 10 ⁵ Pa wider than the pressure measurement range of the second pressure gauge. The pressure can be obtained with high accuracy.

Further, when the pressure of the gas to be measured is in the range of more than 1 Pa, the above conversion equation from the output V of the first pressure gauge determine the pressure P of the gas, a, b and c is a constant, the following equation ( The a, b, and c are obtained by changing the pressure P of the gas and collecting the data of the output V of the first pressure gauge, and the error between the data and the following equation is minimized. so as sought Rukoto is desirable.

この構成によれば、第１圧力計の出力Ｖから気体の圧力Ｐを精度よく求めることができる。

According to this configuration, the gas pressure P can be accurately obtained from the output V of the first pressure gauge.

The first pressure gauge is a Pirani vacuum gauge that includes an electrical resistor that exchanges heat with gas and outputs an electrical signal corresponding to the amount of heat loss of the electrical resistor, the electrical resistor being on the surface The floating film formed so as to straddle the hole of the substrate, the peripheral film formed on the surface of the substrate so as to surround the floating film, and symmetrically arranged with the center of the floating film interposed therebetween A pair of connecting films connecting the outer periphery of the floating film to the peripheral film, and both ends of the electric resistor are formed on the surface of the peripheral film through the surfaces of the pair of connecting films. It is desirable to be drawn out to the other electrode.
According to this configuration, the electric resistor can be made thin, and the pressure measurement range of the Pirani gauge can be expanded. In addition, since the electric resistor is arranged on the surface of the floating film, it becomes possible to suppress the heat outflow from the electric resistor to the substrate, and the outer periphery of the floating film is connected to the peripheral film by the connecting film. Heat outflow from the body to the peripheral membrane can be suppressed. By these, the lower limit of the pressure measurement range of the Pirani gauge can be lowered. Furthermore, both end portions of the electric resistor are drawn out to the electrodes formed on the surface of the peripheral film through the surfaces of the pair of connecting films arranged symmetrically with respect to the center of the floating film. Thereby, even if the thermal expansion coefficient differs between the electrical resistor and the floating membrane, the electrical resistor can be thermally deformed symmetrically. Therefore, the pressure measurement accuracy of the Pirani gauge can be improved.

Further , the first pressure gauge and the second pressure gauge are provided on a substrate to be processed introduced into a processing apparatus having an internal space that can be measured by the first pressure gauge and the second pressure gauge . Is desirable.
The processing apparatus is preferably a sputter processing apparatus.
According to these configurations, it is not necessary to modify the processing apparatus for mounting a pressure measuring device, it is possible to determine the pressure of the gas in the processing apparatus in a simple and low cost. Moreover, the pressure of the gas which acts on a to-be-processed substrate by the process in a processing apparatus can be calculated | required accurately.

Further, it is desirable that a plurality of sets of the first pressure gauge and the second pressure gauge are provided on the substrate to be processed.
According to this configuration, the pressure distribution of the gas acting on the substrate to be processed can be measured easily and accurately at a low cost.

On the other hand, a pressure measuring method according to the present invention includes a first pressure gauge that outputs an electrical signal corresponding to a gas pressure, and an arithmetic device that calculates a conversion formula for obtaining the gas pressure from the output of the first pressure gauge. A pressure measurement method using a pressure measurement device, the pressure measurement device comprising: a second pressure gauge that is disposed in proximity to the first pressure gauge and that measures the pressure of the gas, wherein the second pressure gauge is the first pressure gauge. Measuring the pressure of the gas in a range narrower than the pressure measurement range of the first pressure gauge using the result of the pressure measurement of the gas by the second pressure gauge. anda step of determining the conversion formula is applied to, using a Pirani gauge as said first pressure gauge, characterized by using a septum membrane gauge or piezoresistive pressure gauge as said second pressure gauge .
According to this configuration, even when the output of the first pressure gauge is shifted, the pressure of the gas is measured with the second pressure gauge arranged close to the first pressure gauge, and the conversion formula is calculated using the pressure measurement result. Thus, the gas pressure can be accurately obtained from the output of the first pressure gauge. In addition, since the second pressure gauge measures the gas pressure in a narrower pressure range than the first pressure gauge, the data collection time for calculating the conversion formula can be shortened.

Also, the first pressure gauge and the second pressure gauge mounted on a substrate to be processed, in said processing device having a measurable internal space by the first pressure gauge and the second pressure gauge, the substrate to be processed It is desirable to introduce and measure the pressure in the processing apparatus.
Moreover, it is desirable to use a sputtering apparatus as the processing apparatus.
According to these configurations, it is not necessary to modify the processing apparatus for mounting a pressure measuring device, it is possible to determine the pressure of the gas in the processing apparatus in a simple and low cost. Moreover, the pressure of the gas which acts on a to-be-processed substrate by the process in a processing apparatus can be calculated | required accurately.

  According to this configuration, even when the output of the first pressure gauge is shifted, the pressure of the gas is measured with the second pressure gauge arranged close to the first pressure gauge, and the conversion formula is calculated using the pressure measurement result. Thus, the gas pressure can be accurately obtained from the output of the first pressure gauge. At this time, it is sufficient to employ a second pressure gauge having a pressure measurement range narrower than that of the first pressure gauge, so that the manufacturing cost can be reduced.

Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.
(First pressure gauge, Pirani gauge)
FIG. 1 is an explanatory diagram of a usage pattern of the Pirani vacuum gauge according to the present embodiment, and is a cross-sectional view of a portion corresponding to the line AA in FIG. 3. As shown in FIG. 1, a Pirani vacuum gauge (first pressure gauge) 10 according to the present embodiment is used by being disposed in an opening 2a of a wall surface 2 of a vacuum chamber. A flange 4 is arranged via an O-ring 3 so as to close the opening 2a from the outside. Here, a rubber O-ring seal flange is assumed for simplicity, but a metal seal flange made of all metals may be used. A Pirani gauge 10 is attached to the center of the inner surface of the flange 4, and a plurality of through electrodes 6 are erected on the peripheral edge of the flange 4.

  The Pirani gauge 10 includes a sensor unit 20 in which an electrical resistor 40 corresponding to a filament is formed, a first cover unit 12 that covers the surface of the sensor unit 20, and a second cover unit 18 that covers the back surface of the sensor unit 20. It has. In the sensor unit 20, an electrode 42 for energizing the electric resistor 40 is formed. The electrode 42 is connected to the inner end of the through electrode 6 by a wire 7. The outer end of the through electrode 6 is connected to a bridge circuit described later.

  FIG. 2 is an exploded perspective view of the Pirani vacuum gauge according to the present embodiment. As described above, the Pirani vacuum gauge 10 according to the present embodiment covers the sensor unit 20 on which the electrical resistor 40 is formed, the first cover unit 12 that covers the surface of the sensor unit 20, and the back surface of the sensor unit 20. And a second cover portion 18. In addition, as a constituent material of the sensor part 20, the 1st cover part 12, and the 2nd cover part 18, the silicon | silicone with an oxide film, quartz, sapphire, glass, the compound semiconductor substrate with an insulating film, etc. can be selected. Hereinafter, a silicon substrate with an oxide film having good thermal conductivity will be described as an example.

  The sensor unit 20 includes a substrate 22. A through hole 24 (see FIG. 1) is formed in the center of the substrate 22. An electric insulating film 30 is formed on the surface of the substrate 22 shown in FIG. 2 so as to straddle the through hole. On the surface of the electrical insulating film 30, an electrical resistor 40 and electrodes 42 (42a, 42b) for energizing the electrical resistor 40 are formed. A sealing film 28 made of an Au film is formed around the surface of the electrical insulating film 30. The thickness of the sealing film 28 is formed to about 200 nm, for example.

The first cover part 12 is formed of a silicon substrate. The first cover part 12 is formed with notches 13 and 14 for exposing the electrodes 42a and 42b of the sensor part 20.
A convex portion 17 is formed around the back surface of the first cover portion 12. A sealing film (not shown) formed on the front end surface of the convex portion 17 is bonded to a sealing film 28 formed on the surface of the sensor unit 20, and the first cover unit 12 is fixed to the sensor unit 20. ing. Thereby, the electrical resistor 40 formed in the center of the sensor unit 20 is covered with the first cover unit 12.

On the other hand, a recess 16 is formed from the center to the periphery of the back surface of the first cover portion 12.
As a result, a gas whose pressure is to be measured (hereinafter referred to as “measurement gas”) can be caused to flow from the periphery of the first cover portion 12 to the center to be brought into contact with the electric resistor 40 of the sensor portion 20. It has become.

The second cover portion 18 is formed of a silicon substrate. A sealing film 19 is formed on the entire surface of the second cover portion 18. The sealing film 19 is bonded to a sealing film (not shown) formed on the back surface of the sensor unit 20, and the second cover unit 18 is fixed to the sensor unit 20.
Thereby, the through hole formed in the substrate 22 of the sensor unit 20 is covered by the second cover unit 18.

(Sensor part)
3 is a plan view of the sensor unit, and FIG. 4 is a cross-sectional view taken along line BB in FIG. As shown in FIG. 4, the sensor unit 20 includes a substrate 22 made of a material having low thermal conductivity such as silicon or quartz. The substrate 22 has a substantially square shape in plan view, and one side of the substrate 22 is formed to be about 5 mm, for example. The thickness of the substrate 22 is, for example, about 500 ± 25 μm. A through-hole 24 having a rectangular shape in plan view is formed in the central portion of the substrate 22. The through hole 24 is formed in a tapered shape so that the opening area decreases from the back surface to the front surface of the substrate 22.

An electrical insulating film 30 is formed on the surface of the substrate 22. As a constituent material of the electrical insulating film 30, it is desirable to employ a material having low thermal conductivity such as silicon oxide or silicon nitride.
The thickness of the electrical insulating film 30 is, for example, about 1 to 2 μm. An electric insulating film 30 is disposed so as to straddle the through hole 24 of the substrate 22, and a floating film (membrane) 32 is formed. An electric insulating film 30 is disposed on the surface of the substrate 22 so as to surround the floating film 32, and a peripheral film 36 is formed. A slit 31 communicating with the through hole 24 of the substrate 22 is provided between the floating film 32 and the peripheral film 36.

  As shown in FIG. 3, the floating film 32 is formed in a rectangular shape similar to the through hole 24, and is disposed at the center of the through hole 24. The size of the floating film 32 is, for example, formed such that the short side is 300 μm or less, the long side is 1550 μm or less, and the ratio of the short side to the long side is about 1: 5. In order to connect the outer periphery of the floating film 32 to the peripheral film 36, an electrical insulating film is disposed so as to cross the slit 31, and the connecting films 34 and 35 are formed. Specifically, a pair of first coupling films 34 are formed on both sides in the long side direction across the center of the floating film 32. The first linking film 34 is disposed at the center of the short side of the floating film 32. The size of the first coupling film 34 is, for example, about 100 μm wide and about 500 μm long. In addition, a pair of second coupling films 35 are formed on both sides in the short side direction with the center of the floating film 32 interposed therebetween. The second linking film 35 is disposed at the center of the long side of the floating film 32.

An electrical resistor 40 is formed on the surface of the floating film 32. The electrical resistor 40 is formed in a thin line shape from a metal material that generates Joule heat when energized. In particular, if a material having a high temperature coefficient (change in electrical resistance value per unit temperature) such as Pt, NiCr, W, or the like is adopted as the constituent material of the electrical resistor 40, the measurement accuracy of the Pirani gauge can be improved. Can do.
The electrical resistor 40 is formed to have a film thickness of 200 to 400 nm, a line width of 10 to 20 μm, and a resistance value of 100 to 150Ω, for example. In order to secure the adhesion between the electric resistor 40 and the floating film 32, it is desirable to form an adhesion layer between them. The adhesion layer can be made of a metal material such as Cr or Ti.

  The electrical resistor 40 is formed by patterning fine wires made of the above-described metal material into a bellows shape. Since the length of the thin wire is increased by forming the bellows, the resistance value of the electric resistor 40 can be adjusted, and the surface area for heat exchange with the gas to be measured can be secured. . Instead of the bellows shape, a zigzag shape similar to that of the temperature compensating body 50 described later may be used. The electric resistor 40 is arranged so that the extending direction of the bellows substantially coincides with the long side direction of the floating film 32. In addition, the floating film 32 is formed in a size equivalent to the outer shape of the electric resistor 40, and the ratio of the area of the floating film 32 to the area of the electric resistor 40 is small.

  Connection wires 44 are formed at both ends of the electrical resistor 40. The connection wiring 44 passes through the surfaces of the pair of first connection films 34 and is led out to electrodes 42 (42 a and 42 b) formed on the surface of the peripheral film 36. The electric resistor 40 can be energized from the electrode 42 via the connecting wiring 44.

When the gas to be measured comes into contact with the electrical resistor 40, heat exchange is performed. The amount of heat Qg taken by the measured gas from the electrical resistor 40 is expressed by the following equation.
Qg = Kc (Tf−Tw) P = I ² R (1)
Where Kc is the heat conduction coefficient of the amount of heat transported by the gas to be measured, Tf is the temperature of the electric resistor 40, Tw is the ambient temperature (room temperature) of the electric resistor 40, P is the pressure of the gas to be measured, and I is the electric A current flowing through the resistor 40, R is a resistance value of the electric resistor 40.

  According to Equation (1), it can be seen that the amount of heat Qg taken by the measured gas from the electrical resistor 40 is proportional to the pressure P of the measured gas. Further, since the resistance value R of the electric resistor 40 is substantially proportional to the temperature Tf of the electric resistor 40, if the current I is controlled so that Tf becomes constant, the resistance value R also becomes constant. As a result, the pressure P of the gas to be measured can be calculated from the current I.

  By the way, when the ambient temperature Tw of the electric resistor changes in the equation (1), it becomes difficult to calculate the pressure P of the gas to be measured from the current I. Therefore, a temperature compensator 50 is employed to compensate for changes in the ambient temperature Tw of the electric resistor. The temperature compensator 50 makes the influence of the temperature change of the Pirani gauge zero at a certain pressure point.

As shown in FIG. 3, the temperature compensator 50 is formed on the surface of the peripheral film 36 adjacent to the electric resistor 40. The temperature compensator 50 is formed in a thin line shape using the same material as the electric resistor 40. However, as described later, the resistance value of the temperature compensator 50 needs to be set higher than that of the electric resistor 40. Therefore, the temperature compensating body 50 is formed in a zigzag shape, and the resistance value of the temperature compensating body 50 is secured by increasing the length of the thin line.
One end of the temperature compensation body 50 is connected to an electrode 52 formed on the surface of the peripheral film 36. The other end of the temperature compensating body 50 is connected to one electrode 42 a of the electric resistor 40. As a result, the electrode 42 b functions as a common electrode for the electric resistor 40 and the temperature compensator 50.

  FIG. 5 is a bridge circuit diagram of the Pirani gauge. The electrical resistor 40 and the temperature compensator 50 described above are connected in parallel. Then, the current I flowing through the electric resistor 40 is controlled so that the potential difference V between the electrodes 42a and 52 becomes zero. Since the resistance value of the temperature compensator 50 is set much higher than that of the electric resistor 40, the current flowing through the temperature compensator 50 becomes very small, and the temperature and resistance value of the temperature compensator 50 hardly change. Here, in order to set the potential difference V to 0, the temperature Tf is changed in accordance with the change amount of the ambient temperature Tw of the electric resistor 40. Therefore, Tf−Tw is constant, and changes in the ambient temperature are compensated.

However, the temperature of the temperature compensator 50 may change due to heat transfer from the electrical resistor 40. As shown in FIG. 3, the heat generated in the electric resistor 40 is transmitted to the temperature compensator 50 through the floating film 32, the coupling films 34 and 35, and the peripheral film 36. Therefore, in this embodiment, the groove 39 is formed in the peripheral film between the electric resistor 40 and the temperature compensator 50. The size of the groove 39 is, for example, about 200 μm wide and 400 μm long.
Thereby, it becomes possible to suppress the heat transfer from the electric resistor 40 to the temperature compensator 50, and the temperature change of the temperature compensator 50 can be prevented. Therefore, it becomes possible to reliably compensate for a change in the ambient temperature of the electric resistor 40, and to improve the pressure measurement accuracy.

(Pirani vacuum gauge manufacturing method)
Next, a method for manufacturing the Pirani vacuum gauge according to the present embodiment will be described with reference to FIGS. 6 to 9 are manufacturing process diagrams of the sensor part of the Pirani vacuum gauge.
Here, the micro-Pirani sensor is formed by using an electromechanical system (MEMS) technique that is advantageous for miniaturization of elements at a level of several μm. The MEMS technology is a film formation technology using a metal deposition or sputtering method, a lithography technology capable of producing a pattern of several μm level on a substrate, and a metal, a semiconductor, an oxide film or the like. A large number of elements having a three-dimensional structure are formed on a substrate by using an etching technique or the like that is partially removed using an alkaline chemical solution or a chemical reaction of ions generated by a gas discharge phenomenon.

First, as shown in FIG. 6A, an electrical insulating film 30 is formed on the surface of the substrate 22, and an electrical insulating film 60 is also formed on the back surface of the substrate 22. The electrical insulating films 30 and 60 made of SiO ₂ can be formed by thermally oxidizing the silicon substrate 22. The electrical insulating films 30 and 60 made of SiN can be formed by a vapor deposition method, a CVD method, or the like. Next, a resist 70 is formed on the entire surface of the electrical insulating film 30. Further, the resist 70 existing in the formation region of the electric resistor, the temperature compensator, and their electrodes is removed by a photolithography technique (exposure and development) to form the recess 71.

Next, as shown in FIG. 6B, a Pt / Cr film 40 a is formed on the entire surface of the substrate 22.
The Pt / Cr film 40a includes a lower Cr layer serving as an adhesion layer and an upper Pt layer serving as an electric resistor. The Pt / Cr film 40a is formed inside the recess 71 and the entire surface of the resist 70 by using a sputtering method or the like.

  Next, as shown in FIG. 6C, the resist 70 is removed. The resist 70 can be peeled by a dry process using a plasma ashing apparatus or the like, or a wet process using a resist stripping solution. Along with the peeling of the resist 70, the Pt / Cr film 40a laminated on the resist 70 is removed (so-called lift-off). As a result, the Pt / Cr film 40a formed inside the recess 71 remains on the surface of the electrical insulating film 30, and the electrical resistor 40 is formed. Simultaneously with the electric resistor 40, a temperature compensator and each electrode (both not shown) are formed.

Next, as shown in FIG. 6D, a resist 74 is formed on the entire surface of the electrical insulating film 30.
Further, the resist 74 in the sealing film formation region is removed by a photolithography technique to form the recess 75.
Next, as shown in FIG. 7A, an Au film 28a is formed in the recess 75 and on the entire surface of the resist 74 by sputtering or the like.
Next, as shown in FIG. 7B, the resist 74 is peeled off and the Au film 28a laminated on the resist 74 is removed. As a result, the Au film 28a formed inside the recess 75 remains on the surface of the electrical insulating film 30, and the sealing film 28 is formed.

Next, as shown in FIG. 7C, a resist 78 is formed on the surface of the substrate 22. Here, a resist 78 is also formed on the back surface of the substrate 22. Next, the resist 78 formed on the surface of the substrate 22 is exposed and developed to form a recess 79 in a slit and groove forming region surrounding the floating film. Next, the electrical insulating film 30 is etched using the resist 78 as a mask. This etching process can be performed by RIE (Reactive Ion Etching) or the like using a fluorocarbon gas such as CF ₄ as an etchant.
As a result, as shown in FIG. 7D, slits 31 are formed in the electrical insulating film 30.
By this slit 31, the floating film 32 is separated from the peripheral film 36, and the outer periphery of the floating film 32 is connected to the peripheral film 36 by a connecting film (not shown). At the same time as the slit 31, a groove (not shown) is formed between the electric resistor 40 and the temperature compensator (not shown). Thereafter, the resist 78 is peeled off.

Next, as shown in FIG. 8A, a resist 80 is formed on the front surface and the back surface of the substrate 22.
Next, the resist 80 formed on the back surface of the substrate 22 is exposed and developed to form a recess 81 in the through hole formation region of the substrate 22. Next, using this resist 80 as a mask, the electrical insulating film 60 is etched.
As a result, as shown in FIG. 8B, the electrical insulating film 60 present in the through hole formation region of the substrate 22 is removed, and the recess 61 is formed. Thereafter, the resist 80 on the front surface of the substrate 22 is left and only the resist 80 on the back surface is peeled off.

Next, as shown in FIG. 8C, a resist 84 is filled in the recess 61 of the electrical insulating film 60 on the back side of the substrate 22. Alternatively, the resist 84 may be formed on the entire back surface of the substrate 22 and only the resist present on the surface of the electrical insulating film 60 may be removed using a photolithography technique.
Next, as shown in FIG. 9A, an Au film 29a is formed on the entire back surface of the substrate 22 by sputtering or the like.
Next, as shown in FIG. 9B, the resist 84 is removed and the Au film 29a laminated on the resist 84 is removed. Thereby, the Au film 29a remains only on the surface of the electrical insulating film 60, and the sealing film 29 is formed.

Next, as shown in FIG. 9C, the substrate 22 is wet-etched using the sealing film 29 as a mask. When the electrical insulating film 60 is made of SiO ₂ , TMAH (tetramethylammonium hydroxide) is adopted as the etching liquid for the substrate 22, and when the electric insulating film 60 is made of SiN, KOH is used as the etching liquid. It is desirable to adopt. This makes it possible to ensure an etching selectivity between the silicon substrate 22 and the electrical insulating film 60, and it is possible to etch only the substrate 22 without etching the electrical insulating film 60. Etching of the substrate 22 proceeds obliquely according to the crystal orientation of the silicon constituting the substrate 22. Thus, the through hole 24 is formed in a tapered shape so that the opening area decreases from the back surface to the front surface of the substrate 22.
Thus, the sensor unit 20 of the Pirani vacuum gauge according to the present embodiment is formed.

Next, the first cover portion 12 and the second cover portion 18 shown in FIG. 2 are formed. And the sealing film (not shown) formed in the front end surface of the convex part 17 of the 1st cover part 12 is joined to the sealing film 28 formed in the surface of the sensor part 20, and the 1st cover part 12 is sensored. It fixes to the part 20. Further, the sealing film 19 formed on the upper surface of the second cover portion 18 is brought into close contact with the sealing film (not shown) formed on the lower surface of the sensor portion 20, and the second cover portion 18 is fixed to the sensor portion 20. . Bonding of the sealing film is performed by heating the substrate to 180 to 200 ° C. in the atmosphere and holding the substrate for about 3 to 5 minutes while pressing each substrate with a pressure of ² to 3 kgf / mm ² . Thus, the Pirani vacuum gauge 10 according to the present embodiment is formed.

  By using the MEMS technique described above, it is possible to realize high-precision processing at the μm level, which has been impossible in the past, for the Pt filament in the Pirani vacuum gauge. As a result, a thin-film electrical resistor can be formed, and the measurable pressure range can be expanded.

Factors that determine the upper limit of the pressure range that can be measured with a Pirani gauge are: (1) the thermal conductivity of the gas approaches a constant value, and (2) the measurement sensitivity decreases due to the convection of the gas depending on the orientation of the filament. Can be mentioned. In addition to these, it has been confirmed that the upper limit of the measurable pressure range is proportional to (3) the ratio λ / r of the mean free path λ of the gas and the radius r of the filament. Therefore, in this embodiment, the upper limit of the measurable pressure range can be raised by reducing the radius r by reducing the thickness of the electrical resistor corresponding to the filament. Specifically, the upper limit of the measurement range, which was about 10 ⁴ Pa in the conventional Pirani gauge, can be raised to about 10 ⁵ Pa in the Pirani gauge of this embodiment.

  As described above, the Pirani gauge measures the amount of heat Qg taken by the measurement gas from the filament and calculates the pressure of the measurement gas. The amount of heat Qg is measured by supplementing the filament with the amount of heat. However, the amount of heat actually applied to the filament is not only the amount of heat Qg taken away by the gas but also the sum of the amount of heat Qc flowing out from both ends of the filament and the amount of heat Qr flowing out by radiation.

  The lower limit of the pressure range that can be measured by the Pirani gauge is influenced by (2) the amount of change in the ambient temperature of the filament in addition to (1) the outflow heat quantity Qc, Qr. This is because the amount of heat Qg taken by the low-pressure gas to be measured from the filament is very small, so that it is difficult to measure the amount of heat Qg if the outflow heat amounts Qc and Qr are large. Moreover, in Formula (1), if the variation | change_quantity of the ambient temperature Tw of a filament is large, calculation of the pressure P will become difficult.

  On the other hand, in the Pirani vacuum gauge of this embodiment shown in FIG. 3, it is possible to reduce the amount of heat Qc and Qr flowing out from the electrical resistor 40 by thinning the electrical resistor 40 corresponding to the filament. become. Further, as described above, since the groove portion that blocks heat transfer from the electric resistor to the temperature compensator is provided, it becomes possible to suppress the temperature change of the temperature compensator, and the change in the ambient temperature of the electric resistor can be suppressed. It can be compensated reliably. Therefore, the lower limit of the measurable pressure range can be lowered.

Furthermore, since the electric resistor 40 is formed on the surface of the floating film 32 made of silicon oxide or silicon nitride having a low thermal conductivity, it is possible to suppress the heat outflow from the electric resistor 40 to the floating film 32. In addition, since the electric resistor 40 is disposed on the surface of the floating film 32 that does not directly contact the substrate, it is possible to suppress heat outflow from the electric resistor 40 to the substrate. Further, the floating film 32 is surrounded by the slit 31, the outer periphery of the floating film 32 is connected to the peripheral film 36 by the connecting films 34 and 35, and the groove 39 is formed in the peripheral film 36, so It becomes possible to suppress the heat outflow to. As a result, it is possible to reduce the amount of heat flowing out Qc, Qr, and lower the lower limit of the measurable pressure range. Specifically, the lower limit of the measurement range, which was about 10 ⁻¹ Pa in the conventional Pirani vacuum gauge, can be lowered to about 10 ⁻² Pa in the Pirani vacuum gauge of the present embodiment.

  By the way, a configuration in which a pair of coupling films is arranged asymmetrically with respect to the center of the floating film 32 and both end portions of the electric resistor 40 are led out to the surface of the peripheral film 36 through the surface of the coupling film. However, in this configuration, the electrical resistor 40 is thermally deformed asymmetrically due to the difference in thermal expansion coefficient between the electrical resistor 40 and the floating film 32. As a result, the measurement accuracy of the Pirani gauge may be reduced.

  On the other hand, in the Pirani vacuum gauge according to the present embodiment, a pair of first connection films 34 are arranged symmetrically across the center of the floating film 32, and the electric resistance passes through the surface of the first connection film 34. Both end portions of the body 40 are drawn out to the surface of the peripheral film 36. Thereby, even if the thermal expansion coefficients of the electrical resistor 40 and the floating film 32 are different, the electrical resistor 40 can be thermally deformed symmetrically. Therefore, the pressure measurement accuracy of the Pirani gauge can be improved. In the present embodiment, the measurement sensitivity is improved particularly in the region of 1 to 1000 Pa.

  In the present embodiment, the ratio of the area of the floating film to the area of the electric resistor is reduced, and the heat exchange with the gas is performed exclusively with the electric resistor, so that the pressure measurement accuracy is improved. be able to.

(Second pressure gauge)
The pressure measurement device according to the present embodiment includes a second pressure gauge disposed in proximity to the first pressure gauge. As the second pressure gauge, a diaphragm vacuum gauge, a piezoresistive pressure gauge, a heat conduction vacuum gauge, or the like can be employed.

  FIG. 10 is a side sectional view of the diaphragm vacuum gauge. The diaphragm vacuum gauge 101 is also formed by using the MEMS technique, similarly to the above-described Pirani vacuum gauge. The diaphragm vacuum gauge 101 is configured by laminating a first substrate 102, a second substrate 110, and a third substrate 120 made of silicon, glass, or the like.

  A through hole 104 is formed in the center of the first substrate 102. A recess 114 is formed on the back surface of the second substrate 110 so as to communicate with the through hole 104. The second substrate 110 is thinned by the recess 114 to form a diaphragm 115. An ion diffusion layer 116 doped with impurity ions is formed from the surface peripheral portion of the second substrate 110 to the formation portion of the diaphragm 115.

  In addition, the back surface periphery of the third substrate 120 is bonded to the front surface periphery of the second substrate 110. A recess 122 is formed in the center of the back surface of the third substrate 120, and a vacuum chamber 125 hermetically sealed by the recess 122 is formed. A getter agent 106 for adsorbing moisture and the like is provided inside the vacuum chamber 125.

  A first electrode 131 is formed on the surface of the ion diffusion layer 116 in the formation part of the diaphragm 115. A second electrode 132 is formed on the back surface of the third substrate 120. The first electrode 131 and the second electrode 132 are arranged to face each other at a predetermined distance, and the capacitor 130 is formed. A reference (zero point shift correction) electrode 134 is formed on the back surface of the third substrate 120 adjacent to the second electrode 132. The second electrode 132 and the reference electrode 134 are drawn to the surface through the through hole of the third substrate 120.

  In the diaphragm vacuum gauge 101 described above, the diaphragm 115 is deformed toward the vacuum chamber 125 by the pressure of the gas to be measured introduced from the through hole 104 of the first substrate 102. Along with this deformation, the distance between the first electrode 131 and the second electrode 132 changes, and the capacitance of the capacitor 130 changes. By replacing the change in capacitance with an electric signal, the pressure of the gas to be measured can be detected.

  FIG. 11 is a side sectional view of the piezoresistive pressure gauge. This piezoresistive pressure gauge 200 is also formed by using the MEMS technology, similarly to the above-described Pirani gauge. The piezoresistive pressure gauge 200 is configured by laminating and arranging a first substrate 202, a second substrate 210, and a third substrate 220 made of silicon, glass, or the like, like the above-described diaphragm vacuum gauge.

  In the diaphragm vacuum gauge described above, the capacitor including the first electrode is formed in the diaphragm forming portion, whereas in the piezoresistive pressure gauge 200, a metal is formed on the surface of the ion diffusion layer 216 in the diaphragm 215 forming portion. A wiring 230 is formed. The metal wiring 230 is made of a piezoelectric material such as PZT that mutually converts a mechanical signal and an electrical signal.

  In the piezoresistive pressure gauge 200, the diaphragm 215 is deformed toward the vacuum chamber 225 by the pressure of the gas to be measured introduced from the through hole 204 of the first substrate 202. With this deformation, the metal wiring 230 is also deformed, so that its resistance value changes. By replacing the change in resistance value with an electric signal, the pressure of the gas to be measured can be detected.

(Arithmetic unit)
The pressure measuring device according to the present embodiment includes an arithmetic device that calculates a conversion formula for obtaining the pressure of the gas to be measured from the output of the Pirani gauge.
FIG. 12 is a graph showing the relationship between the pressure of the gas to be measured (horizontal axis) and the output (vertical axis) of the Pirani gauge, and FIG. 12 (a) is a graph in which the vertical axis is a linear scale. ) Is a log scale on the vertical axis.

  As described above, the Pirani gauge measures the amount of heat Qg taken from the filament by the gas to be measured. The amount of heat Qg is measured by supplementing the filament with the amount of heat. However, the amount of heat actually applied to the filament is not only the amount of heat Qg taken away by the gas but also the sum of the amount of heat Qc flowing out from both ends of the filament and the amount of heat Qr flowing out by radiation. Here, Qg increases in proportion to the pressure of the gas to be measured (see Equation (1)), but Qc and Qr are constant values regardless of the pressure. Therefore, as indicated by a black circle in FIG. 12A, the output of the Pirani gauge includes an offset corresponding to Qc and Qr. Therefore, as indicated by a white circle in FIG. 12A, the output corresponding to Qg is obtained by subtracting the offset from the output of the Pirani gauge.

It is known that the output of the Pirani gauge corresponding to Qg varies with the diameter d of the filament and the mean free path λ of the gas. The mean free path λ of gas is an average value of a flight distance from a collision of moving gas molecules to the next collision.
(A) When the mean free path λ is sufficiently larger than the diameter d of the filament, that is, when the pressure of the gas to be measured is low, Qg increases in proportion to the pressure (see Formula (1)).
(A) On the other hand, when the mean free path λ is small, that is, when the pressure of the gas to be measured is high, Qg becomes a constant value regardless of the pressure.

  As shown by a black square in FIG. 12B, when the pressure of the gas to be measured is 1 Pa or less, the above (A) is dominant, and the output of the Pirani gauge shows linearity. On the other hand, as shown by a white square in FIG. 12B, when the pressure of the gas to be measured is 1 Pa or more, the above (A) becomes dominant, and the output of the Pirani gauge shows non-linearity. It becomes like this.

  In the prior art, a correspondence table between the output of the Pirani vacuum gauge and the pressure of the gas to be measured is created, and the pressure of the gas to be measured is obtained by applying the output of the Pirani vacuum gauge to this correspondence table. In this case, there is a problem that a large amount of memory is required to store the correspondence table. Therefore, in this embodiment, a conversion formula for obtaining the pressure of the gas to be measured is calculated from the output of the Pirani gauge, and the pressure of the gas to be measured is obtained by substituting the output of the Pirani gauge for this conversion formula. In this case, since a large amount of memory is not required, the manufacturing cost can be reduced, and the pressure of the gas to be measured can be accurately obtained.

In FIG. 12B, when the pressure of the gas to be measured is 1 Pa or less, the relationship between the output V of the Pirani gauge and the pressure P of the gas to be measured can be described by the following equation.
V = a * P (2)
The constant a is obtained by the least square method or the like. That is, it is only necessary to collect the data of the output V of the Pirani gauge by changing the pressure P of the gas to be measured, and obtain the constant a that minimizes the error between each data and Equation (2). Solving this equation (2) for P, a conversion formula for obtaining the pressure P of the gas to be measured from the output V of the Pirani gauge can be obtained when the pressure P of the gas to be measured is 1 Pa or less.

On the other hand, in FIG. 12B, when the pressure of the gas to be measured is 1 Pa or more, the output of the Pirani gauge gradually approaches a constant value according to the above (A). Therefore, it is considered that the relationship between the output V of the Pirani gauge and the pressure P of the gas to be measured can be described by the following equation.
V = a / ((c / P) +1) (3)
However, as a result of experiments, it has been found that using the following equation can describe the relationship between the two with higher accuracy.
V = a / ((c / P) ^b +1) (4)
Also in this case, the constants a, b, and c are obtained by the least square method or the like. That is, the data P of the output of the Pirani gauge is collected by changing the pressure P of the gas to be measured, and constants a, b, and c that minimize the error between each data and Equation (4) may be obtained.
If this equation (4) is solved for P, the following equation is obtained.

この式が、被測定ガスの圧力Ｐが１Ｐａ以上の場合において、ピラニ真空計の出力Ｖから被測定ガスの圧力Ｐを求めるための換算式となる。

This formula is a conversion formula for obtaining the pressure P of the gas to be measured from the output V of the Pirani gauge when the pressure P of the gas to be measured is 1 Pa or more.

  By the way, according to the equation (1), the output of the Pirani gauge corresponding to Qg shifts as the ambient temperature Tw of the electric resistor of the Pirani gauge and the resistance value R change. In this case, in order to recalculate the conversion formula, it is necessary to recalculate the constants a, b, and c in the formula (4). As described above, in order to obtain the constants a, b, and c, it is necessary to change the pressure P of the gas to be measured and measure the output V of the Pirani gauge. Here, in order to monitor the pressure P of the gas to be measured, it is necessary to use a pressure gauge other than the Pirani gauge. However, it is troublesome to attach another pressure gauge every time the constants a, b, and c are obtained again.

  Therefore, in this embodiment, the second pressure gauge such as the above-described diaphragm vacuum gauge is disposed in the vicinity of the Pirani vacuum gauge (first pressure gauge). According to this configuration, even when the output of the Pirani gauge is shifted, the pressure of the gas is measured with the second pressure gauge arranged close to the first pressure gauge, and the conversion formula is recalculated using the pressure measurement result. Thus, the gas pressure can be accurately obtained from the output of the first pressure gauge. By providing a second pressure gauge for pressure monitoring in advance, it is not necessary to attach another pressure gauge each time the constants a, b, and c in Equation (4) are obtained again. Further, by placing the second pressure gauge close to the Pirani vacuum gauge, the pressure of the gas to be measured acting on the Pirani vacuum gauge can be accurately measured. Moreover, if a 2nd pressure gauge is created with a Pirani vacuum gauge using MEMS technology, the increase in manufacturing cost can be suppressed to the minimum.

As described above, the pressure measurable range of the Pirani vacuum gauge according to this embodiment is as wide as 10 ⁻² to 10 ⁵ Pa, whereas the pressure measurable range of one diaphragm vacuum gauge or piezoresistive pressure gauge is It is as narrow as 3-4 digits. Therefore, the whole range of 1 to 10 ⁵ Pa cannot be measured with one second pressure gauge. Therefore, in the present embodiment, the pressure P of the gas to be measured is changed only in a part of the pressure range of 1 to 10 ⁵ Pa, the data of the output V of the Pirani vacuum gauge is collected, and the constant a in Expression (4) , B, c are obtained. In this case, it is sufficient to employ one second pressure gauge having a narrower pressure measurable range than the Pirani vacuum gauge, and thus the manufacturing cost can be reduced. Moreover, since the gas pressure is measured in a pressure range narrower than that of the Pirani gauge, the data collection time for calculating the conversion formula can be shortened.

The inventor of the present application, by changing the pressure of the measurement gas in the range of 50 to 10 ⁵ Pa, it was found that a formula that can be applicable to the whole of 1~10 ⁵ Pa (4) are calculated. As shown in FIG. 12 (b), the output of the Pirani gauge is characterized (inflection point) in the range of 50 to 10 ³ Pa, nonlinearity is strong in this range. Therefore, the pressure P of the gas to be measured is changed in the range of 50 to 10 ⁵ Pa including 50 to ^{10 3} Pa, the output V data of the Pirani gauge is collected, and the constants a, b, It is desirable to obtain c. In this case, one second pressure gauge having a pressure measurable range at 50 to 10 ⁵ Pa may be provided. Equation (4) obtained here accurately describes the relationship between the output V of the Pirani gauge and the pressure P of the gas to be measured for the whole of 1 to 10 ⁵ Pa. If Equation (4) is solved for P, a conversion formula for obtaining the pressure P of the gas to be measured from the output V of the Pirani gauge when the pressure P of the gas to be measured is 1 Pa or more can be obtained.

FIG. 13 is a graph for confirming the accuracy of the gas pressure to be measured obtained from the conversion formula. In FIG. 13, the measured value of the measured gas pressure is plotted on the horizontal axis, and the calculated value of the measured gas pressure obtained from the conversion formula is plotted on the vertical axis. The graph of FIG. 13 shows that the calculated value of the measured gas pressure obtained from the conversion formula and the measured value are in good agreement for 10 ⁻² to 10 ⁵ Pa, which is the pressure measurable range of the Pirani gauge. ing. Therefore, the gas pressure can be accurately obtained from the output of the Pirani gauge.

(Process gas pressure measurement)
Next, a pressure measuring device (portable sensor) in which a Pirani vacuum gauge (first pressure gauge) and a second pressure gauge are provided on a substrate to be processed introduced into the processing apparatus will be described.
FIG. 14 is a block diagram of the pressure measuring device. The pressure measuring device 185 includes a plurality of sets of Pirani vacuum gauges (first pressure gauges) 10 and diaphragm vacuum gauges (second pressure gauges) 100. The Pirani gauge 10 and the second pressure gauge 100 are connected to the controller 170 via drive circuits 65 and 165, respectively. The controller 170 includes an A / D, D / A converter 172, an arithmetic unit (CPU) 174 that calculates the conversion formula as described above, a memory 176 that records the conversion formula, and an interface that performs data communication with the outside. 178. Further, a battery 180 that supplies power to the drive circuits 65 and 165, the controller 170, and the like is provided.

  FIG. 15 is a schematic configuration diagram of a substrate surface mounting type pressure measuring device. In FIG. 15, a pressure measuring device 185 is mounted on the surface of the substrate to be processed 190 introduced into the processing apparatus, and a portable sensor is configured. The substrate 190 to be processed is equivalent to a substrate used for actual processing in the processing apparatus, and the material is silicon, glass, ceramics, compound semiconductor, SiC, or the like, and the diameter is about 50 to 300 mm. . A plurality of sets of Pirani vacuum gauges 10 and second pressure gauges 100 are arranged substantially evenly on the surface of the substrate to be processed 190, and the respective Pirani vacuum gauges 10 and second pressure gauges 100 are arranged close to each other. The Pirani vacuum gauge 10 and the second pressure gauge 100 may be directly formed on the substrate to be processed 190 by MEMS technology, or may be manufactured separately from the substrate to be processed 190 and attached to the substrate to be processed 190. A controller 170 is provided on the surface of the substrate 190 to be processed. The controller 170 includes the above-described drive circuit, arithmetic unit (CPU) and memory, and is hermetically sealed with a cap (not shown).

  FIG. 16 is a schematic configuration diagram of a circuit-internal type pressure measuring device, FIG. 16 (a) is a perspective view, and FIG. 16 (b) is a cross-sectional view taken along line CC in FIG. 16 (a). The portable sensor shown in FIG. 16B includes an upper surface plate 190 and a lower surface plate 194, a side wall portion 193 disposed at a peripheral edge portion therebetween, and a storage chamber 195 surrounded by these. . The upper surface plate 190 and the lower surface plate 194 are formed to have a planar size equivalent to the substrate to be processed introduced into the processing apparatus. The side wall portion 193 is formed in a ring shape and is fixed to the lower surface plate 194. A sealing member 192 such as an adhesive or an O-ring is disposed between the front surface of the side wall portion 193 and the back surface of the upper surface plate 190. Thus, the storage chamber 195 surrounded by the upper surface plate 190, the side wall portion 193, and the lower surface plate 194 is hermetically sealed.

  A plurality of sets of Pirani vacuum gauges 10 and second pressure gauges 100 are arranged substantially evenly on the outer surface of the upper surface plate 190. Drive circuits 65 and 165 are installed inside the storage chamber 195 and on the inner surface of the upper surface plate 190. The Pirani gauge 10 and the second pressure gauge 100 are connected to the drive circuits 65 and 165 through contact holes 196 formed in the upper surface plate 190. Inside the storage chamber 195 and on the inner surface of the lower surface plate 194, a semiconductor element including an arithmetic device 174 and a memory 176 is installed. An interface 178 that performs data communication with the outside is installed on the inner surface of the lower surface plate 194, and is drawn out to the outside through a through hole 197 formed in the upper surface plate 190. A battery 180 is mounted on the inner surface of the lower surface plate 194. In addition to this, the lower plate 194 itself may be constituted by a battery.

Next, a pressure measurement method for measuring a pressure in the processing apparatus by introducing a substrate to be processed (portable sensor) equipped with the pressure measuring apparatus into the processing apparatus will be described with reference to FIG.
First, the substrate to be processed on which the pressure measuring device 185 is mounted is first introduced into the processing apparatus. Next, the conversion formula is calculated. Specifically, the pressure of the gas to be measured in the processing apparatus is changed in the range of 50 to 10 ⁵ Pa, and measurement is performed by the Pirani vacuum gauge (first pressure gauge) 10 and the second pressure gauge 100. Here, the pressure of the gas to be measured is detected by the second pressure gauge 00 whose pressure measurable range is set to 50 to 10 ⁵ Pa. A plurality of output data of the Pirani gauge 10 corresponding to the pressure of the gas to be measured is measured.

  Next, the arithmetic unit 174 performs the curve fitting of Expression (4) on the output data of the Pirani vacuum gauge 10. Specifically, the constants a, b, and c in the equation (4) are determined using the least square method or the like so that the error between the output data of the Pirani gauge 10 and the equation (4) is minimized. Substituting the constants a, b, and c determined here into the inverse function of Equation (4), a conversion equation for obtaining the pressure of the gas to be processed from the output of the Pirani gauge 10 is obtained. The calculation of the conversion formula is performed individually for all Pirani gauges 10. The determined constants a, b, and c are stored in the memory 176.

  Next, predetermined processing is performed on the substrate to be processed on which the pressure measuring device 185 is mounted in the processing apparatus. For example, in the case of a sputtering apparatus, the inside of the apparatus is depressurized, an inert gas is introduced, and a high voltage is applied. Next, measurement is performed by the Pirani gauge 10 and the measurement result is output to the arithmetic unit 174. The arithmetic unit 174 first reads the constants a, b, and c from the memory 176 and constructs a conversion formula. Then, the output data of the Pirani gauge 10 is substituted into a conversion formula to obtain the pressure of the gas to be measured. The obtained pressure is stored in the memory 176 and is read out via the interface 178 after the processing is completed. It is also possible to read the pressure immediately after being obtained by wireless communication via the interface 178. The read pressure is used for monitoring the treatment process.

  As described above, the output of the Pirani gauge changes when the ambient temperature Tw of the electric resistor, the resistance value R, or the like changes even if the pressure of the gas to be measured is constant. Therefore, the recalculation of the conversion formula (re-determination of the constants a, b, and c in Formula (4)) may be performed only when changes in the ambient temperature Tw, resistance value R, and the like of the electrical resistor are expected. Note that the recalculation of the conversion formula may be performed periodically (for example, for each processing lot).

  Note that, in a processing apparatus that performs continuous processing in a plurality of processing chambers, it is particularly effective to distribute a substrate to be processed on which the pressure measuring device 185 is mounted to each processing chamber. Since the substrate to be processed on which the pressure measuring device 185 is mounted is formed in the same size as the substrate to be processed flowing through each processing chamber, it is not necessary to modify each processing chamber. In this case, it is desirable to recalculate the conversion formula before starting the processing in each processing chamber.

As described above in detail, in the pressure measuring device according to the present embodiment, the Pirani vacuum gauge and the second pressure gauge are provided on the substrate to be processed introduced into the processing apparatus. Thereby, it is not necessary to modify the processing apparatus for mounting the pressure measuring device, and the pressure of the gas in the processing apparatus can be measured easily and at low cost. Moreover, the pressure of the gas which acts on a to-be-processed substrate by the process in a processing apparatus can be measured accurately.
Moreover, it was set as the structure by which the to-be-processed substrate was provided with several sets of 1st pressure gauge and 2nd pressure gauge. As a result, the pressure distribution of the gas acting on the substrate to be processed can be measured easily and accurately at a low cost.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, and includes those in which various modifications are made to the above-described embodiments without departing from the spirit of the present invention. That is, the specific materials and configurations described in the embodiments are merely examples, and can be changed as appropriate.

  For example, it is possible to measure a substrate temperature distribution during processing by mounting a thermometer together with a pressure gauge on a substrate to be processed. As the thermometer, a resistor thermometer, a thermocouple, or the like can be employed. Among them, the resistor thermometer can be built on the substrate to be processed together with the Pirani vacuum gauge and the diaphragm vacuum gauge using the MEMS technology. Moreover, it is also possible to use the temperature compensation body of a Pirani vacuum gauge as a resistor thermometer.

It is explanatory drawing of the usage pattern of the Pirani vacuum gauge which concerns on embodiment. It is a disassembled perspective view of the Pirani vacuum gauge which concerns on embodiment. It is a top view of a sensor part. It is sectional drawing of the sensor part in the BB line of FIG. It is a bridge circuit diagram of a Pirani gauge. It is a manufacturing-process figure of the sensor part of a Pirani vacuum gauge. It is a manufacturing-process figure of the sensor part of a Pirani vacuum gauge. It is a manufacturing-process figure of the sensor part of a Pirani vacuum gauge. It is a manufacturing-process figure of the sensor part of a Pirani vacuum gauge. It is side surface sectional drawing of a diaphragm vacuum gauge. It is side surface sectional drawing of a piezoresistive pressure gauge. It is a graph which shows the relationship between the pressure (horizontal axis) of to-be-measured gas, and the output (vertical axis) of a Pirani vacuum gauge. It is a graph for confirming the accuracy of the gas pressure to be measured obtained from the conversion formula. It is a block diagram of a pressure measuring device. It is a schematic block diagram of a substrate surface mounting type pressure measuring device. It is a schematic block diagram of a circuit interior type pressure measuring device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Pirani vacuum gauge (1st pressure gauge) 22 ... Board | substrate 24 ... Through-hole (hole part) 32 ... Floating film 34 ... 1st connection film | membrane (connection film) 36 ... Peripheral film | membrane 39 ... Groove part 40 ... Electric resistor 50 ... Temperature compensator 174 ... arithmetic unit 185 ... pressure measuring device 190 ... substrate to be processed 100 ... second pressure gauge

Claims (10)

A first pressure gauge that outputs an electrical signal corresponding to the pressure of the gas;
An arithmetic device for calculating a conversion formula for obtaining the pressure of the gas from the output of the first pressure gauge;
A second pressure gauge disposed close to the first pressure gauge and measuring the pressure of the gas,
The second pressure gauge measures the pressure of the gas in a range narrower than the pressure measurement range of the first pressure gauge,
The calculation device is a pressure measurement device that calculates the conversion formula applied to a range wider than the pressure measurement range of the second pressure gauge using the pressure measurement result of the gas by the second pressure gauge,
The first pressure gauge is a Pirani gauge;
Pressure measuring device, wherein the second pressure gauge is septa film gauge or piezoresistive pressure gauge. The first pressure gauge is a Pirani gauge that includes an electrical resistor that exchanges heat with gas and outputs an electrical signal corresponding to the amount of heat loss of the electrical resistor,
The pressure measurement range of the first pressure gauge is 10 ⁻² Pa to 10 ⁵ Pa,
The pressure measuring device according to claim 1, wherein a pressure measurement range of the second pressure gauge is 50 Pa or more and 10 ⁵ Pa or less. When the pressure of the gas to be measured is in the range of 1 Pa or more,
The conversion equation for obtaining the gas pressure P from the output V of the first pressure gauge is expressed by the following equation, where a, b, and c are constants:
Wherein a, b and c, by changing the pressure P of the gas, the data of the output V of the first pressure gauge was collected, Rukoto prompts error between the data and the following equation is minimized The pressure measuring device according to claim 2.

The first pressure gauge is a Pirani vacuum gauge that includes an electrical resistor that exchanges heat with gas and outputs an electrical signal corresponding to the amount of heat loss of the electrical resistor,
A floating film formed so as to straddle the hole of the substrate by disposing the electric resistor on the surface;
A peripheral film formed on the surface of the substrate so as to surround the floating film;
A pair of linking membranes arranged symmetrically across the center of the buoyant membrane and linking the outer periphery of the buoyant membrane to the peripheral membrane,
4. The device according to claim 1, wherein both end portions of the electric resistor are led out to electrodes formed on the surface of the peripheral film through the surfaces of the pair of coupling films. 5. Item 1. The pressure measuring device according to item 1.   The first pressure gauge and the second pressure gauge are provided on a substrate to be processed which is introduced into a processing apparatus having an internal space that can be measured by the first pressure gauge and the second pressure gauge. The pressure measuring device according to any one of claims 1 to 4.   The pressure measuring apparatus according to claim 5, wherein the processing apparatus is a sputtering processing apparatus.   The pressure measuring apparatus according to claim 5, wherein a plurality of sets of the first pressure gauge and the second pressure gauge are provided on the substrate to be processed. A first pressure gauge that outputs an electrical signal corresponding to the pressure of the gas;
An arithmetic device for calculating a conversion formula for obtaining the pressure of the gas from the output of the first pressure gauge;
A pressure measurement method using a pressure measurement device, the pressure measurement device comprising: a second pressure gauge that is disposed in proximity to the first pressure gauge and measures the pressure of the gas;
The second pressure gauge measures the pressure of the gas in a range narrower than the pressure measurement range of the first pressure gauge;
The arithmetic unit obtains the conversion formula applied to the entire pressure measurement range of the first pressure gauge using the pressure measurement result of the gas by the second pressure gauge;
Have
Using a Pirani vacuum gauge as the first pressure gauge,
Pressure measurement method which comprises using a septum membrane gauge or piezoresistive pressure gauge as said second pressure gauge.   The first pressure gauge and the second pressure gauge are mounted on a substrate to be processed, and the substrate to be processed is introduced into a processing apparatus having an internal space that can be measured by the first pressure gauge and the second pressure gauge. The pressure measurement method according to claim 8, wherein the pressure in the processing apparatus is measured.   The pressure measuring method according to claim 9, wherein a sputtering processing apparatus is used as the processing apparatus.

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