JP2002098611A - Measuring method and device for leakage gas and evaluation device of the leakage gas measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method for accurately measuring the small flow rate of leakage gas. SOLUTION: In the leakage gas measuring method for measuring the gas quantity leaking out of an inspection object S1 having a nearly closed space wherein helium gas is sealed, a process exhausting a chamber by way of a first exhaust pipe 12 connected with the chamber 11 containing the inspection object, a process for accumulating the gas leaking out of the inspection object into the chamber by closing the chamber for a specific time TS, a process for measuring the total amount LS of the gas by supplying the gas accumulated in the chamber after elapsing for the specific time to a mass spectrometer 21, and a process calculating the leakage gas flow rate Lout by dividing the total amount LS of the measured gas by the specific time TS are contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a semiconductor device or the like which has a substantially sealed space and determines the airtightness of an inspection object. The present invention relates to a leak gas measuring method for measuring an amount of gas leaking into an object, a leak gas measuring device, and an evaluation device of the leak gas measuring device.

[0002]

2. Description of the Related Art An apparatus of this type is disclosed, for example, in Japanese Patent No. 2957.
No. 220 is disclosed. The operation of this apparatus will be described with reference to FIG. 29 showing the same apparatus. First, a test object 200 in which helium gas is sealed is housed in a chamber 201. Next, the valve 202 is opened and the valve 203 is closed, and the gas in the chamber 201 is exhausted by the vacuum pump 204. Next, the valve 202 is closed, and helium gas leaking from the inspection object 200 is accumulated in the chamber 201 for a predetermined time. Then, the valve 203 is opened and the vacuum pump 205 is driven to guide the helium gas leaking from the inspection object 200 to the detector 206. Detector 206
Measures the flow rate of helium gas passing through the detector 206. Note that the standard tube 207 supplies a predetermined helium gas flow rate to the detector 206 in order to calibrate the detector 206 before measuring the flow rate.

In the above-described conventional apparatus, the inspection object 20
The reason that the helium gas leaking from zero is accumulated in the chamber 201 for a predetermined time period is that the flow rate of the helium gas passing through the detector 206 after the valve 203 is opened can be immediately set to the saturation value (steady value). Based on Thereby, the above-mentioned conventional apparatus can shorten the flow measurement time.

[0004]

However, in the above-mentioned conventional apparatus, since the flow rate of the helium gas leaking from the inspection object 200 is assumed to be sufficiently large with respect to the detection sensitivity of the detector 206, the leak occurs. When the helium gas flow rate is extremely small, the gas flow rate cannot be measured accurately, and a value for determining the airtightness of the inspection object 200 cannot be obtained.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a first feature of the present invention is to determine the airtightness of an inspection object having a substantially sealed space in which a predetermined gas is sealed. In the leak gas measuring method for measuring the amount of gas leaking from the inspection object in order to exhaust gas in the chamber through an exhaust passage connected to the chamber containing the inspection object, Closing the exhaust passage connected to the chamber for a predetermined time to accumulate the gas leaking from the inspection object in the chamber, and measuring the total amount of the accumulated gas after the elapse of the predetermined time. Process.

[0006] According to this, an exhaust passage connected to the chamber is closed for a predetermined time to accumulate gas leaking from the inspection object in the chamber, and measurement is performed after increasing the density of the leaked gas. Therefore, the total amount of the leaked gas can be accurately measured. As a result, even if the flow rate of gas leaking from the inspection object is very small,
A value relating to airtightness can be obtained with high accuracy.

In this case, the method may further include an impurity gas adsorption step of starting adsorption of an impurity gas other than the predetermined gas existing in the chamber before starting the step of measuring the total amount of the accumulated gas. It is suitable. Preferably, the impurity gas adsorption step is a step of cooling the chamber.

According to this, the impurity gas existing in the chamber is reduced by adsorption before the start of the measurement.
The total amount of the accumulated gas can be measured with higher accuracy. Further, the adsorption of the impurity gas can be easily achieved by cooling the chamber.

A second feature of the present invention is a leaked gas measuring method for measuring the amount of gas leaking from the outside to the inside of the inspection object in order to determine the airtightness of the inspection object having a substantially enclosed space. Supplying the gas into a chamber containing the inspection target, exhausting the inspection target through an exhaust passage connected to the inspection target, and connecting to the inspection target. Closing the exhaust passage that has been closed for a predetermined time and accumulating the gas leaking from the chamber into the inspection object in the inspection object, and the total amount of the accumulated gas after the elapse of the predetermined time And the step of measuring

[0010] According to this, the leaked gas leaking (intruding) from outside to inside of the inspection object is accumulated in the inside of the inspection object for a predetermined time, and the density of the leak gas is increased before measurement. The total amount of leaked gas can be accurately measured. As a result, even when the flow rate of the leaking gas is very small, a value relating to airtightness can be obtained with high accuracy.

In the gas leakage measuring method having the first and second features, the step of measuring the total amount of the accumulated gas includes the step of supplying the accumulated gas to a flow rate measuring device. And integrating a value corresponding to the output of the flow rate measuring device.

[0012] According to this, even if the detection sensitivity of the flow rate measuring device provided in the leak gas amount measuring device is not sufficient for an extremely small gas flow rate and substantial measurement is impossible, By accumulating the leaked gas and supplying it to the same flow rate measuring device, measurement by the same flow rate measuring device becomes possible. By integrating a value corresponding to the output of the measuring device, the total amount of the leaked gas is obtained. Can be measured.

Further, in the above method for measuring a leaked gas,
Including the step of estimating the background noise of the same output based on the output of the flow measurement device, the step of integrating a value corresponding to the output of the flow measurement device, the estimated from the output of the flow measurement device It is preferable that the value obtained by subtracting the background noise be integrated as a value corresponding to the output of the flow rate measuring device.

According to this, the background noise (background) having the same output is estimated based on the output of the flow rate measuring device, so that the actual background noise can be accurately grasped. The total amount of the gas can be determined with high accuracy.

Further, the step of estimating the background noise is performed based on an output of the flow rate measuring device during a predetermined period before and after a period in which the accumulated gas is supplied to the flow rate measuring device. Preferably, the step is a step of estimating noise.

According to this, even when the background noise drifts (fluctuates) with time, the background noise during the period in which the total amount of the accumulated gas is measured can be accurately estimated. .

In any of the above cases, it is preferable that the method further comprises a step of dividing the total amount of the measured gas by the predetermined time to obtain an amount corresponding to the flow rate of the leaking gas. is there.

According to this, it is possible to obtain an amount that well represents the degree of airtightness of the inspection object.

A third feature of the present invention is that a chamber for accommodating an inspection object, a flow measuring unit, an exhaust passage connecting between the chamber and the flow measuring unit, and an exhaust passage. A leak control device provided with an on-off valve for opening and closing the exhaust passage, and a measurement control device, wherein the measurement control device closes the on-off valve to seal the chamber for a predetermined time, and Leak gas accumulating means for accumulating gas leaking from the inspection object in the chamber; opening and closing the on-off valve after the lapse of the predetermined time, supplying the accumulated gas to the flow rate measuring device and measuring the flow rate And integrating means for integrating a value corresponding to the output of the device and measuring the total amount of the accumulated gas.

According to this, the chamber is sealed for a predetermined time and gas leaking from the inspection object is accumulated in the chamber, and after the elapse of the predetermined time, the accumulated gas is transferred to the same flow rate measuring device. Supplied. Then, the total amount of the accumulated gas is measured by integrating a value corresponding to the output of the flow measurement device.

Therefore, even if the detection sensitivity of the flow rate measuring device provided in the leaked gas measuring device is not sufficient for an extremely small amount of gas flow and substantial measurement is impossible, the same flow rate measuring device Since the flow rate is increased by supplying the stored gas to the apparatus, measurement by the flow rate measurement apparatus becomes possible.

In this case, the leakage gas measurement device includes an exhaust device connected between the on-off valve and the flow rate measurement device in the exhaust passage, and the measurement control unit includes the leakage gas measurement device. It is preferable to include exhaust control means for opening the on-off valve and driving the exhaust device to exhaust the inside of the chamber before the accumulation means starts accumulating the gas leaking from the inspection object. .

According to this, after the chamber containing the test object is evacuated, the leaked gas is accumulated in the chamber. For this reason, the amount of impurity gas in the gas to be measured is reduced, and the amount of leaked gas to be measured is accurately measured.

In this case, it is preferable that an adsorbing means for adsorbing an impurity gas other than the gas existing in the chamber is provided. It is preferable that the suction means includes a cooling means for cooling the chamber.

According to this, since the impurity gas existing in the chamber is reduced by adsorption before the start of the measurement,
The total amount of the accumulated gas can be measured with higher accuracy. Further, the adsorption of the impurity gas can be easily achieved by cooling the chamber.

[0026] Preferably, the measurement control device includes cooling control means for starting the operation of the cooling means and cooling the chamber before measuring the total amount of the stored gas by the integration means. is there.

A fourth feature of the present invention resides in that a chamber to which a predetermined gas is supplied, a flow measuring device, and an exhaust passage connecting between the inspection object contained in the chamber and the flow measuring device. A leakage gas measuring device comprising: an on-off valve interposed in the exhaust passage for opening and closing the exhaust passage; and a measurement control device, wherein the measurement control device closes the on-off valve to open the inspection object. For a predetermined time, and a leak gas accumulating means for accumulating the predetermined gas leaking into the inspection object; and opening and closing the on-off valve after the elapse of the predetermined time to measure the accumulated gas. And integrating means for integrating the value according to the output of the flow rate measuring device and measuring the total amount of the accumulated gas.

According to this, the inspection object is sealed for a predetermined time, and the gas in the chamber is accumulated in the inspection object. After the elapse of the predetermined time, the accumulated gas is transmitted to the flow rate measuring device. Supplied. Then, the total amount of the accumulated gas is measured by integrating a value corresponding to the output of the flow measurement device.

Therefore, similarly to the leak gas amount measuring device having the third feature, the detection sensitivity of the flow rate measuring device provided in the leak gas measuring device is not sufficient for an extremely small gas flow rate, and substantial measurement is not possible. Even if the measurement is impossible, the flow rate is increased by supplying the stored gas to the flow rate measuring device, so that measurement by the flow rate measuring device becomes possible.

Further, in the leak gas measuring device having the third and fourth features, the measurement control means divides the total amount of the gas obtained by the integration means by the predetermined time to perform the leak. It is preferable to provide a flow rate calculating means for obtaining a gas flow rate.

According to this, it is possible to obtain a quantity that well represents the degree of airtightness of the inspection object.

A fifth feature of the present invention is the evaluation device for a leaked gas measuring device having the above-mentioned third feature, wherein the evaluation device has a known leak amount of the predetermined gas per unit time. A standard leak source, a connection passage connecting the standard leak source to the chamber or a closed chamber communicating with the chamber, an opening / closing valve interposed in the connection passage to open and close the same, and an exhaust valve Valve opening means for opening the on-off valve interposed in the connection passage for a predetermined time while the mounted on-off valve is closed.

Since the leaked gas measuring device having the third characteristic is for measuring the amount of the predetermined gas accumulated in the chamber, the leaked gas measuring device is a chamber connected to a standard leak source or a sealed air communicating with the chamber. By supplying gas from the standard leak source to the chamber for a predetermined time, it becomes possible to accumulate a known amount of gas in the chamber, and by measuring the amount of this gas, the leak gas measuring device An assessment can be made.

According to a sixth aspect of the present invention, there is provided an evaluation device for a leaked gas measuring device having the above-described third characteristic, wherein the evaluation device includes a sealed gas storing a predetermined gas having a known gas amount. A chamber, a connection passage connecting the closed chamber and the chamber, an on-off valve interposed in the connection passage for opening and closing the connection passage, and an on-off valve interposed in the exhaust passage closed. And valve opening means for opening the on-off valve interposed in the connection passage until the gas concentration in the closed chamber becomes equal to the gas concentration in the chamber.

The leak gas measuring device having the third characteristic is for measuring an extremely small amount of gas accumulated in the chamber, and a general standard leak source is housed in the chamber instead of the inspection object. In this case, since the amount of leak is too large, the detection accuracy of the leak gas measuring device cannot be evaluated. On the other hand, the apparatus having the above-mentioned features prepares a sealed chamber storing a known gas amount, communicates the chamber with the chamber until the gas concentrations of the two become equal, and transfers the known gas amount to the closed chamber and the closed chamber. Divide according to the volume ratio of the chamber. This makes it possible to accumulate a small amount of gas in the chamber that is known and is appropriate for the accuracy evaluation of the leaked gas measuring device, so that the accuracy of the leaked gas measuring device can be evaluated. .

According to a seventh aspect of the present invention, there is provided an evaluation device for a leaked gas measuring device having the above fourth feature, wherein the evaluation device has a known amount of leakage of the predetermined gas per unit time. A certain standard leak source, a connection passage connecting the standard leak source and the exhaust passage, a portion between the on-off valve and the inspection object or a closed chamber communicating with the same, and the connection passage. An on-off valve interposed to open and close the connection passage, and valve opening means for opening the on-off valve interposed in the connection passage for a predetermined time while the on-off valve interposed in the exhaust passage is closed And that it had.

In the leak gas measuring device having the fourth feature, the predetermined gas accumulated in the inspection object is guided to a flow measuring device via an exhaust passage to measure the amount of the gas. From the above, by supplying gas from the standard leak source to the exhaust passage connected to the standard leak source or a sealed chamber communicating with the exhaust passage for a predetermined time, a known amount of gas is supplied to the flow rate measuring device. By measuring the amount of this gas, the leakage gas measuring device can be evaluated.

According to an eighth aspect of the present invention, there is provided an evaluation apparatus for a leak gas measuring apparatus having the above-mentioned fourth aspect, wherein the evaluation apparatus stores a predetermined amount of the predetermined gas having a known gas amount. 1 closed chamber, a second closed chamber connected to the exhaust passage, a connection passage connecting the first closed chamber and the second closed chamber, and a connection passage interposed in the connection passage to open and close the connection passage. An on-off valve, and an on-off valve interposed in the connection passage with the on-off valve interposed in the exhaust passage closed, with the gas concentration in the first closed chamber and the gas concentration in the second closed chamber. Is provided with a valve opening means for opening the valve until is equal.

The leak gas measuring device having the fourth feature measures an extremely small amount of gas accumulated in the inspection object. If the inspection object is replaced with a general standard leak source, In addition, since the leak amount is too large, the detection accuracy of the leak gas measuring device cannot be evaluated. On the other hand, the apparatus having the above-mentioned features prepares a first closed chamber in which a known gas amount is accumulated, and communicates the first closed chamber with the second closed chamber until the gas concentrations of the two become equal. It is divided according to the volume ratio of the first closed chamber and the second closed chamber. This makes it possible to accumulate a small amount of gas, which is known and is appropriate for the accuracy evaluation of the leaked gas measuring device, in the second closed chamber, so that the accuracy of the leaked gas measuring device can be evaluated. Becomes

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A leak gas measuring apparatus 10 according to a first embodiment of the present invention shown in FIG. 1 includes a chamber 11 and a first exhaust pipe 1 connected to the chamber 11 and forming an exhaust passage.
2, a first opening / closing valve 13 interposed in the first exhaust pipe 12 for opening and closing the exhaust passage, an opening / closing valve driving device 14, and a valve opening / closing detection switch 15 for detecting the opening / closing state of the first opening / closing valve 13. A second exhaust pipe 16 that constitutes an exhaust passage branched from the first exhaust pipe 12; an exhaust device 17 connected to the second exhaust pipe 16; and a second exhaust pipe 16 that is interposed in the second exhaust pipe 16. A second on-off valve 1 for opening and closing an exhaust passage from a branch point Q between the first exhaust pipe 12 and the second exhaust pipe 16 to the exhaust device 17
8, an on-off valve driving device 19, a third exhaust pipe 20 forming an exhaust passage branched from the first exhaust pipe 12, a mass analyzer 21 connected to the third exhaust pipe 20,
A pressure gauge 22 connected to the exhaust pipe 20;
0, a display device 31, and a recording device 32.

The chamber 11 can maintain a closed state with the first on-off valve 13 closed (closed).
It has a hood (not shown) that can be opened and closed, so that the inspection object (test body) S1 can be accommodated therein.

The first on-off valve 13 is an electromagnetic valve, and is opened and closed by an on-off valve driving device 14 connected to the measurement control device 30 and responding to an instruction signal from the measurement control device 30. I have. The valve on / off switch 15 is connected to the measurement control device 30, takes out the open / close state of the first on / off valve 13 as a detection signal, and supplies the detection signal to the measurement control device 30.

The evacuation device 17 is composed of a vacuum pump and is connected to the measurement control device 30.
The operation is started or stopped in response to an instruction from the user. Note that the vacuum pump includes a rotary pump, a turbo pump, a diffusion pump, and the like, and these are used alone or in combination so as to obtain a predetermined degree of vacuum.

The second on-off valve 18 is an electromagnetic valve, and is opened and closed by an on-off valve driving device 19 connected to the measurement control device 30 and responding to an instruction signal from the measurement control device 30. I have.

The mass analyzer 21 functions as a flow rate measuring device, continuously measures the flow rate of a gas having a specific mass number (helium gas in this example), and measures the size according to the flow rate. (Actually, a current is output, and this current is converted into a voltage, output L). The mass analyzer 21 includes, as schematically shown in FIG. 2, a first pipe 21a to which a third exhaust pipe 20 is connected,
On the other hand, the second pipe 21b having a predetermined angle and the first pipe 21b
A permanent magnet 21c disposed at a connection between the tube 21a and the second tube 21b, an ionization accelerator 21d including a tungsten filament disposed at an end of the first tube 21a, and an end of the second tube 21b Tube 21e having a collector plate (target plate) disposed in the second tube 21e
b, and a plate 21f having an opening near the center in the radial direction.

With this configuration, the mass analyzer 21 can
The gas introduced through the exhaust pipe 20 is ionized and accelerated, and is emitted as an ion beam along the first pipe 21a. The direction of the ions in the ion beam is changed by the electromagnet 21c. Among them, ions having a larger mass number than helium ions cannot change through the opening angle of the plate 21f because the angle of change is small. Similarly, ions having a lower mass number than helium ions have a larger change angle,
It cannot pass through the opening of the plate 21f. As a result, only the helium ions pass through the opening of the plate 21f and reach the collector plate of the vacuum tube 21e. As a result, a current corresponding to the number of molecules of the helium gas introduced through the third exhaust pipe 20 is output from the vacuum tube 21e, and this output is converted into a voltage by a current-voltage converter (not shown).

Referring again to FIG. 1, the pressure gauge 22 is connected to the measurement control device 30 to measure the pressure P in the third exhaust pipe 20 and supply the measurement result to the measurement control device 30. It has become. The measurement control device 30 includes a microcomputer that executes a program to be described later, and is connected to a display device 31 that is a display for displaying a measurement result and a recording device 32 that prints the measurement values on recording paper. ing.

The chamber 11 and the first on-off valve 1
Even when the distance between the mass spectrometer 3 and the mass analyzer 21 and the pressure gauge 22 is heated to about 150 ° C. in the chamber 11 and the first on-off valve 13 (that is, when baking described later is executed), It is preferable that the mass analyzer 21 and the pressure gauge 22 are set so as not to be affected by the heat.

Next, the operation of the leak gas measuring device 10 configured as described above will be described with reference to FIGS. The measurement in FIG. 3 is started (step 308).
The steps from the end to the end (step 395) indicate the steps of the program (main routine) executed by the measurement control device 30, and the other steps indicate the steps performed by the operator. FIG. 4 shows a time interruption routine executed by the measurement control device 30 every time the sampling time TSAMPLE elapses.

First, at step 302, the inspection object S1
A helium gas at a known pressure (for example, 100 (Pa)) is sealed therein. Here, the inspection target S1 will be described. The inspection target S1 is, for example, a semiconductor yaw rate sensor having a vibrator. As shown in a schematic cross-sectional view in FIG. , Lid 43
It consists of The base 42 and the lid 43 are welded and fixed at the peripheral edge to form a substantially closed space, and the semiconductor element 41 is fixed in the closed space. Semiconductor element 4
From 1, a connection line 44 extends through the base 42.
Further, the helium gas is sealed by welding and fixing the base 42 and the lid 43 in a helium atmosphere having the known pressure. The enclosed helium gas mainly leaks from the welded portion and the penetrating portion of the connection wire.

Next, the operator places the inspection object S1 in the chamber 11 in step 304, and
The hood of the chamber 11 is closed by closing the chamber 11.

Next, the operator activates the measurement control device 30 in step 308 and operates a measurement start button (not shown) to start measurement. Accordingly, the measurement control device 30 proceeds to step 310 to operate the exhaust device 17, and in step 312, the first and second on-off valves 13,
18 is opened (opened). As a result, each part including the chamber 11 and connected to the exhaust device 17 (the first exhaust pipe 12, the first on-off valve 13, the second exhaust pipe 16, the second on-off valve 18, the third
The discharge of the impurity gas existing in the exhaust pipe 20, the mass analyzer 21, and the pressure gauge 22) is started. Next, the measurement control device 30 proceeds to step 314, where the chamber 11 and the first
The on-off valve 13 is heated to about 150 ° C. for a predetermined time by a heating device (not shown), and then a cooling period is provided for a predetermined time. This step is called baking and is performed in chamber 1
This is a step in which the impurity gas molecules adsorbed on the first and first on-off valves 13 are released and exhausted, and this step is performed in order to improve the measurement accuracy of the helium gas later.

When the process of step 314 is completed (when the cooling period is completed), the measurement control device 30 proceeds to step 316, and the output P of the pressure gauge 22 is set to a predetermined pressure (1
0 ^{-2 (Pa))} follows whether it, i.e., the chamber 1
1. It is determined whether the inside of the first, second, third exhaust pipes 12, 16, 20 and the mass analyzer 21 has reached a predetermined degree of vacuum. Then, the predetermined degree of vacuum has not been reached (“N
o ”), the measurement control device 30 repeatedly executes the same step 316.

Thereafter, when the output P of the pressure gauge 22 becomes lower than the predetermined atmospheric pressure, the measurement control device 30 proceeds to step 316.
In step 318, an instruction signal is sent to the on-off valve driving device 14 to close the first on-off valve 13 (closed).
Start 1 Next, the measurement control device 30 proceeds to step 3
At 22 the timer T is reset and started (time measurement is started), and at step 324 the value of the sampling permission flag F is set to "1" and the value of the counter n is set to "1".

On the other hand, as described above, the measurement control device 30
Is the sampling time of the time interrupt routine shown in FIG.
Each time TSAMPLE elapses, the process starts from step 400, and in step 405, it is determined whether the value of the sampling permission flag F is "1". Accordingly, when the value of the sampling permission flag F is set to “1” in step 324, the measurement control device 30 proceeds to step 4
At 05, the determination is “Yes” and the process proceeds to step 410,
The output value L of the mass analyzer 21 at that time is measured value L (n).
(= L (1)) and the time t at that time is stored as the measurement time t (n) (= t (1)).

Next, the measurement controller 30 proceeds to step 41
Proceeding to 5, the counter value n is incremented by "1", and proceeding to step 420, it is determined whether or not the counter value n has become equal to a predetermined value ne + 1. The predetermined value ne + 1 is set so that a sufficient number of samplings are performed when the counter value n becomes equal to the predetermined value ne + 1, in other words, a sufficient time has elapsed since the first on-off valve 13 was opened. (The gas stored in the chamber 11 is
, A predetermined time has elapsed). At this stage, since the value of n is “2”, the measurement controller 30 determines “N” in step 420.
o ", the routine proceeds to step 495, and this routine is temporarily ended. Thereafter, every time the sampling time elapses,
The output value L at that time is stored as the measurement value L (n), and the time t at that time is stored as the measurement time t (n), and the value of the counter n is incremented by “1”.
When the value of the sampling permission flag F is "0" at the time of execution of step 405, the measurement control device 30 immediately proceeds to step 495 and ends this routine once.

Referring again to FIG. 3, the measurement control device 3
If it is 0, it is determined whether or not the timer T has counted a predetermined time (accumulation time) TS in step 326. During the period in which the predetermined time TS elapses, the helium gas sealed in the substantially closed space of the inspection object S1 is used.
Leaks into the chamber 11 and accumulates. The accumulation time TS is suitably about 5 minutes, but may be several hundred hours when measuring an extremely small amount of leakage.

When a predetermined time TS has elapsed, the measurement control device 3
In step 326, “Yes” is determined in step 326, and the process proceeds to step 328.
4, the first on-off valve 13 is opened (opened), and in the next step 330, the valve on / off detection switch 15 is opened.
Monitor whether the first on-off valve 13 has been opened based on the output of.

When the first opening / closing valve 13 is opened, the valve opening / closing detection switch 15 sends a signal to that effect to the measurement control device 30, and the measurement control device 30 determines "Yes" in step 330. To step 332 to store the time t at that time as the first opening / closing valve opening timing tv, and to step 334 to store the output value L of the mass analyzer 21 at that time as the valve opening output Lv. . The measurement control device 30 monitors the pressure P measured by the pressure gauge 22 before and after the first on-off valve 13 is opened and closed, and when the pressure P changes greatly, the measurement control device 30 increases the pressure P from the inspection target S1. It is determined that there is a leak, the fact is displayed on the display device 31, and the subsequent measurement is stopped.

Next, the measurement controller 30 proceeds to step 336.
Then, it is determined whether or not the value of the sampling permission flag F has become “0”. This sampling permission flag F
When the value of the counter n is increased by the execution of step 415 of the routine shown in FIG. 4 and becomes equal to the value ne + 1, the value of “” is determined based on the determination of “Yes” in step 420 of the measurement control device 30. , At step 425. Therefore, when a sufficient number of samplings have been performed and the value of the sampling permission flag F has been changed to “0”, the measurement control device 30 proceeds to step 336 in FIG.
Is determined to be "Yes", and the process proceeds to step 338 and thereafter to start data analysis.

That is, the measurement control device 30 executes step 34
The maximum peak value Lp is selected from the measured values L (1) to L (ne) sampled at 0 (see FIG. 6), and the actual measurement time τ is calculated in the subsequent step 342. This actual measurement time τ is equal to the valve opening output Lv taken in step 334.
Then, the reference output Le is calculated based on the following Expression 1 and then, as shown in FIG. 6, a time at which an output equal to the reference output Le is obtained is obtained as a reference time te. Using the first opening / closing valve opening timing tv taken in step 332, it is obtained by performing a calculation based on the following equation (2). Note that e on the right side of Equation 1 is the base of the natural logarithm.

[0062]

## EQU1 ## Le = (Lp-Lv) / e + Lv

[0063]

Τ = te−tv

Next, the measurement controller 30 proceeds to step 344.
To extract the measured value L (n) belonging to the time (tv−m · τ) to the time tv and the time (tv + k · τ) to the time (tv + (k + m) · τ). The value “m” is desirably 2 to 5, and the value “k” is desirably 1 to 5. Here, m = 2 and k = 2. Then, the measurement control device 30 proceeds to step 346, and as shown in FIG.
An approximate straight line passing through (n) is obtained by the least squares method. This approximate straight line represents a change in the background noise in the output of the measurement control device 30.

Next, the measurement controller 30 proceeds to step 34.
8, the value obtained by subtracting the approximation straight line from the measured value L (n) belonging to the time tv to the time tv + k · τ (a value corresponding to the output of the mass analyzer 21 as a flow rate measuring device) is integrated, and the measured value is obtained. The area S of the portion surrounded by L (n) and the approximate straight line is obtained (see FIG. 8). This area S is a value corresponding to the total amount LS of the helium gas leaking from the inspection object S1 into the chamber 11 and accumulated in the chamber 11, and therefore, step 348 is performed in step 348. This is a step of substantially measuring the total amount LS.

Next, the measurement controller 30 proceeds to step 350
Then, the total amount LS is divided by the accumulation time TS according to the following equation 3 to obtain a flow rate Lout of helium gas leaking from the inspection object S1 (a leakage amount of helium gas per second).

[0067]

Lout = LS / TS

Thereafter, the measurement control device 30 proceeds to step 35
2. Total amount of helium gas LS and accumulation time obtained above in 2
The TS and the leaked helium gas flow rate Lout are numerically displayed on the display of the display device 31, and at step 35
4 and these measured values L (n), t (n), L
v and tv are plotted as shown in FIG.
Proceed to 95 to end the measurement.

As described above, in the leak gas measuring apparatus 10 of the first embodiment, the helium gas leaking from the inspection object S1 is accumulated in the chamber 11 for the accumulation time TS, and the accumulated helium gas is measured. The total amount LS is measured, and the total amount LS is divided by the accumulation time TS to obtain the flow rate Lout of the leaking helium gas. Thereby, even if the flow rate Lout of the leaked helium gas is smaller than the detection sensitivity of the mass spectrometer 21, measurement is performed by introducing the leaked gas to the mass spectrometer 21 within a short time after accumulating the leaked gas. Since the gas flow rate increases, the same flow rate L
out can be measured. In other words, the sensitivity of the leaked gas measuring device 10 is a value obtained by multiplying the sensitivity of the mass analyzer 21 when the first on-off valve 13 is maintained in the open state by the accumulation time TS.

A period during which the accumulated gas is guided to the mass analyzer 21 and measured (time tv to time tv + k · τ).
(Time (tv−m · τ) to time tv)
And time (tv + k · τ) to time (tv + (k + m) ·
τ)), the background noise of the mass analyzer 21 is obtained based on the output of the mass analyzer 21, and the value obtained by subtracting the background noise is integrated to obtain the total amount LS of the helium gas. An error due to fluctuation (drift) of the background noise is reduced, and an accurate helium gas amount LS can be obtained. Further, at the beginning of the measurement, the first on-off valve 13 is opened, and the exhaust device 1 is opened.
7 as well as the chamber 11 and the first on-off valve 1
Since 3 is baked, gas molecules adsorbed on them can be removed in advance, and the measurement accuracy can be improved.

Further, since the opening of the first opening / closing valve 13 is detected by using the valve opening / closing detection switch 15, the measurement start timing can be accurately detected, and as a result, the measurement accuracy can be improved.

The above steps 350 and 35
2 and the measured flow rate Lout (that is, the measured leakage
Quantity R (Pa · m^Three/ sec (He conversion)) to the equivalent standard leak amount L₀(P
a ・ m ^Three/ sec (Air conversion)) and display it on the display device 31.
A step of displaying more may be provided. Equivalent standard leak
Quantity L₀Means that the pressure difference between the inside and outside of the inspection object S1 is 1 atm,
When the ambient temperature is 25 ° C.,
The amount of air leaking from the^Three)
It is calculated according to the following equation (4). Note that Equation 4
And P0_HeIs a helium gas enclosed in the inspection object S1.
Pressure (Pa), P₀Is the atmospheric pressure (1.0 × 10^Five(Pa)), M_air
Is the molecular weight of air (28.7), M_HeIs the molecular weight of helium
(4).

[0073]

[Number 4] _{R = P0 He · (L 0} / P 0) · (M air / M He) 1/2

Further, in the first embodiment, the helium gas is welded to the inspection object S1 by welding the lid 43 and the base 42 of the inspection object S1 in a helium gas atmosphere of a known pressure. Inspection object S
1 is installed in a bombing tank, and the inside of the bombing tank is pressurized with helium gas at a pressure Pe (Pa) for a predetermined pressurization time t1.
It may be sealed by a bombing method in which pressure is applied only for (sec). If by the bombing method, the relationship of the following Expression 5 is satisfied between the measured leak rate R (measured flow rate Lout) equivalent standard leak rate L _0, equivalent to the measured leak rate R in accordance with the same number 5 it may be converted to a standard leak rate L _0. In Equation 5, t2 (sec) is the time from the end of pressurization by bombing to the start of measurement of the amount of helium gas leakage, and other parameters are the same as Equation 1.

[0075]

(Equation 5)

In the first embodiment, it is preferable to limit the volume of the chamber 11 to 2 to 1000 times the inspection object S1. This is because degassing released from the inner wall of the chamber 11 is suppressed, and background noise can be reduced. The leak gas measuring device 10 can be configured to simultaneously measure a plurality of inspection objects S1 at a time, but even in this case, the volume of the chamber 11 is the minimum that can accommodate the inspection object to be measured. Is desirable.

Next, a leak gas measuring device according to a second embodiment of the present invention will be described with reference to FIG. 9. The leak gas measuring device 50 supplies a helium gas of a constant pressure to the chamber 11 with respect to the configuration. The first point is that the helium gas cylinder 51 is connected via the on-off valve 52 and the first exhaust pipe 12 is connected to the inspection object S2 and communicates with the substantially closed space of the inspection object S2. This is different from the embodiment.

The leak gas measuring device 5 thus configured
A measurement method using 0 will be described with reference to FIG. In FIG. 10, the measurement is started (step 308).
The steps from the end to the end (step 1095) are the steps of the program executed by the measurement control device 30.
These steps are performed by the measurement control device 3 of the first embodiment.
0 is substantially the same as each step of the program to be executed, and the other steps are steps performed by the operator. Also,
The measurement control device 30 of the second embodiment executes a time interruption routine shown in FIG.

In the second embodiment, first, step 1
At 002, the inspection object S2 is set in the chamber 11, and at step 1004, the hood (not shown) is closed to seal the chamber 11. Next, in step 1006, the on-off valve 52 is opened to supply helium gas from the helium gas cylinder 51 into the chamber 11, and the inside of the chamber 11 is set to a known pressure (for example, 5 atm). Note that the measurement sensitivity is improved in proportion to the pressure of the helium gas in the chamber 11. For this reason, it is desirable that the pressure of the helium gas be set to a maximum pressure equal to or lower than the pressure resistance of the inspection object S2 and the chamber 11.

Hereinafter, the measurement control device 30 of the second embodiment
Performs the measurement of the leaked helium gas similarly to the measurement control device 30 of the first embodiment. In this case, after the first on-off valve 13 is closed in step 318, “Y
During the period until the determination is “es” (that is, the period until the accumulation time TS elapses), the helium gas in the chamber 11 leaks (enters) into the inspection object S2 and accumulates in the inspection object S2. In this regard, the gas exhausted by the exhaust device 17 is the gas in the inspection object S2 and the gas in the inspection object S2.
Helium gas in the space communicating with the helium gas measured by the mass analyzer 21
Is different from the first embodiment in that the gas is not helium gas but leaked from the chamber 11 and accumulated in the substantially closed space of the inspection object S2, and is different from the first embodiment in other points. Substantially the same.

That is, the leak gas measuring device 50 according to the second embodiment closes the first on-off valve 13 to store the helium gas leaking from the chamber 11 into the inspection object S2 during the accumulation time TS.
And then open the first on-off valve 13 to supply the stored helium gas to the mass spectrometer 21 and obtain a value corresponding to the output of the mass spectrometer 21 (a value obtained by subtracting the background noise). The total amount LS is obtained by integration, and this amount is divided by the accumulation time TS to obtain an amount Lout corresponding to the leaked gas flow rate indicating the airtightness of the inspection object S2.

Therefore, in the leak gas measuring device 50 according to the second embodiment, after accumulating the gas in the inspection object S2, the gas is guided to the mass analyzer 21 within a short time, so that the flow rate of the measured gas increases. Therefore, as in the case of the leak gas measuring apparatus 10 of the first embodiment, there is an effect that a small amount of leak gas can be measured with high accuracy. In this case, the leakage gas measuring device 50
Is expressed by the following equation (6). In Equation 6, Sbase is the sensitivity of the mass analyzer 21 when the first on-off valve 13 is open, TS is the accumulation time of the helium gas, and PHe is the helium gas pressure (known pressure) in the chamber 11. ).

[0083]

[Equation 6] Sens (Pa · m ³ / sec) = Sbase (Pa · m ³ / sec) / TS (s
ec) / PHe (atm)

As is apparent from Equation 6, the detection sensitivity Sens of the leaked gas measuring device 50 increases as the accumulation time TS increases and the pressure PHe of the helium gas supplied to the chamber 11 increases.
The larger is the better. When actually measured, the detection sensitivity of this type of conventional device was 1 ×
10 ⁻¹² (Pa · m ³ / sec), whereas the detection sensitivity of the leaked gas measuring device 50 is 1 × 10
It was confirmed to be ⁻¹⁵ (Pa · m ³ / sec).

FIG. 11 shows the total amount (integral value) L when the helium standard leak source having a known leak amount is installed in the chamber 11 and the accumulation time TS is changed.
The result of having measured S is shown. Since the leaked helium flow rate from the helium standard leak source is a value obtained by dividing the total amount LS by the accumulation time TS, in FIG. 11, it is represented by the angle between the measurement point and the origin (the inclination of the measurement point). As shown in FIG. 11, since each measurement point exists on the same straight line passing through the origin, the leaked gas measuring device 50
It is understood that the leaked gas flow rate can be measured accurately regardless of the TS.

Here, a technique for further improving the measurement resolution of the leak gas measuring devices 10 and 50 according to the first and second embodiments will be described with reference to FIGS. FIG. 12 shows a change in the output of the mass analyzer 21 when the accumulated helium gas gradually reaches the mass analyzer 21 after the opening of the first on-off valve 13 at time tv,
FIG. 13 shows the output of the mass analyzer 21 when the accumulated helium gas reaches the mass analyzer 21 more quickly than the case shown in FIG. 12 after the opening of the first on-off valve 13 at time tv. Shows the change. In this example, the total amount LS of the accumulated helium gas is assumed to be equal, and therefore, the area S of the portion surrounded by the curve formed by the measured value L (n) and the above-described approximate line Lba of the background noise is: In theory they would be equal.

However, in the case shown in FIG. 12, the difference ΔLp between the maximum value Lp of the output of the mass spectrometer 21 and the approximate line Lba of the background noise is the same as FIG.
Since it is equivalent to the resolution Bn of the mass spectrometer 21 shown therein, the measured value L (n) as well as the maximum value Lp
And the difference between the background noise and
As a result, the area S (ie, the total amount LS of the helium gas)
Cannot be obtained with high accuracy. This is a phenomenon that occurs when the accumulated helium gas reaches the mass analyzer 21 for a long time. Therefore, in order to avoid such a phenomenon, it is desirable to adopt a method described below.

(1) In order to shorten the time required for the accumulated helium gas to move to the mass analyzer 21, the first on-off valve 1
The conductance of the exhaust passage (exhaust pipe) system including
(L / sec) or more.

(2) In the first embodiment, the volume (volume) inside the chamber 11 is set to the inspection object S in order to promptly discharge the accumulated helium gas out of the chamber 11.
Limit to 1 to 100 times 1.

(3) In the first embodiment, in order to allow the accumulated helium gas to easily escape from the inner wall of the chamber 11, the inner wall is polished by an electrolytic polishing process or the like to reduce the surface roughness. Reduce its surface area. In addition to or instead of this, in order to suppress the adsorption of helium gas to the inner wall of the chamber 11, the chamber 11
The inner wall 11 is coated with TiN or the like.

Next, an evaluation device of the leak gas measuring device 10 according to the first embodiment will be described. In general, the leak gas measuring apparatus 10 installs a standard leak source having a certain known leak amount (a predetermined gas flow rate per unit time) in the chamber in place of the inspection object S1, and performs a normal measurement. It is evaluated by comparing the obtained flow rate Lout with the leak amount of the standard leak source. However, since the leak gas measuring device 10 has an extremely high sensitivity for measuring the leak gas amount of an inspection object having an extremely small leak gas amount (leak amount), the standard leak source currently available is In some cases, the leak amount is too large to evaluate the leak gas measuring device 10. In particular, this problem is remarkable when the amount of leakage of the inspection target is very small and the accumulation time TS is set to a long time.

An evaluation device 60 connected to the leak gas measuring device 10 shown in FIG. 14 addresses the above-described problem. This evaluation device 60 includes a standard leak source of helium gas having a known leak amount. 61 and the first having a volume of VA
A chamber (sealed chamber) 62 and a second chamber (sealed chamber 6) having a volume VB smaller than the volume VA of the first chamber 62.
3). Further, the evaluation device 60 includes a first connection pipe 64 connecting the standard leak source 61 and the first chamber 62.
, A second connection pipe 65 connecting the first chamber 62 and the second chamber 63, and a third connection pipe 66 connecting the second chamber 63 and the chamber 11 of the leaked gas measuring device 10.

The first connection pipe 64 is provided with a third on-off valve 67a for opening and closing the passage of the connection pipe 64. This third
The on-off valve 67a is an electromagnetic valve, and is opened and closed by an on-off valve driving device 67b which is connected to the measurement control device 30 and responds to an instruction signal from the measurement control device 30. Similarly, the second and third connection pipes 65 and 66 are provided with fourth and fifth on-off valves 68a and 69a for opening and closing the passages of the connection pipes 65 and 66, respectively. The fourth and fifth on-off valves 68a and 69a are electromagnetic valves, and are connected to the measurement control
Opening / closing valve drive devices 68b, 6 responding to an instruction signal from 0
9b respectively open and close.

Next, the evaluation device 6 configured as described above
0 and the operation of the leaked gas measuring device 10 using the evaluation device 60 will be described with reference to FIG. In FIG. 15, steps that perform the same processing as the steps shown in FIG. 3 are denoted by the same reference numerals as those shown in FIG. Also, the gas accumulation start (step 1506) to end (step 1595) in FIG.
Shows the steps of the program executed by the measurement control device 30, and the other steps show the steps performed by the operator. Further, also in this case, the measurement control device 30 executes the routine shown in FIG. 4 every time the sampling time TSAMPLE elapses.

First, step 1 following step 1500
At 502, the exhaust device 17 is operated, and
At 04, the mass spectrometer 21 is started, and from step 1506, processing for accumulating helium gas for evaluation is started.

That is, the measurement control device 30
At 08, it is determined whether or not the time required for starting the mass spectrometer 21 (particularly, heating of the tungsten filament) has elapsed.
Proceeding to 10, the first to fifth on-off valves 13, 18, 67a,
68a and 69a are opened. At this time, the previous step 1
Since the exhaust device 17 is operated at 502, the execution of step 1510 starts the exhaust of the impurity gas present in all the parts connected to the exhaust device 17. The third on-off valve 67a is opened because the standard leak source 6 accumulated between the standard leak source 61 and the third on-off valve 67a (ie, the first connection pipe 64 and the third on-off valve 67a).
This is for sufficiently exhausting the helium gas from 1 as well.

Next, the measurement control device 30 executes step 1
Proceeding to 512, the output P of the pressure gauge 22 becomes equal to the predetermined pressure (10
^-2 (Pa)) is determined. Then, when it is determined that the predetermined degree of vacuum has not been reached (“No”), the measurement control device 30 repeatedly executes the same step 1512.

If the output P of the pressure gauge 22 becomes smaller than the predetermined atmospheric pressure as the evacuation proceeds, the measurement control device 30 determines “Yes” in step 1512 and determines in step 151
Proceeding to 4, the first opening / closing valve 13, the fourth opening / closing valve 68a, and the fifth opening / closing valve 69a are closed, and only the standard leak source 61 and the first chamber 62 are in communication. Next, the measurement control device 30 resets the timer T in step 1516 and starts (starts time measurement).
It is determined whether or not the value of the timer T has become larger than a predetermined time T1 (sec), that is, whether or not the predetermined time T1 has elapsed since the timer T was reset in step 1516.

When the predetermined time T1 has elapsed, the measurement control device 30 determines “Yes” in step 1518, proceeds to step 1520, and closes the third on-off valve 67a in step 1520. The helium gas amount V1 accumulated in the first chamber 62 when the predetermined time T1 has elapsed.
Is a value represented by the following equation (7). In Equation 7, Lst is the amount of leak (unit: Pa · m ³ / sec) of the test (calibration) of the standard leak source 61.

[0100]

V1 = Lst · T1 (Pa · m ³ )

Next, the measurement controller 30 proceeds to step 15
Proceeding to 22, the fourth on-off valve 68a is opened. As a result, only the first chamber 62 and the second chamber 63 are in communication. Then, the measurement control device 30 proceeds to step 1524 to reset the timer T and starts again. The process proceeds to step 1526 to determine whether or not the value of the timer T has become larger than a predetermined time T2 (sec). Is reset in step 1524, it is determined whether or not a predetermined time T2 has elapsed. When the predetermined time T2 has elapsed, the routine proceeds to step 1528, where the fourth on-off valve 68a is closed.

The predetermined time T2 is set to a time required for the helium gas concentrations in the first chamber 62 and the second chamber 63 to be equal (or a slightly longer time). Therefore, when the predetermined time T2 has elapsed, the helium gas amount V stored in the second chamber 63
2 is a value represented by the following equation 8. As is apparent from Equation 8, the helium gas amount V2 is smaller than the helium gas amount V1.

[0103]

V2 = V1 · VB / (VA + VB)

Next, the measurement control device 30 executes step 153.
In step 1530, the fifth on-off valve 69a is opened. Thereby, the second chamber 63 and the chamber 1
Only 1 is in communication. Then, the measurement control device 30 proceeds to step 1532 and resets and starts the timer T again, and proceeds to step 1534 to determine whether or not the value of the timer T has become larger than a predetermined time T3 (sec). Is reset in step 1532, it is determined whether or not a predetermined time T3 has elapsed. When the predetermined time T3 has elapsed, the routine proceeds to step 1536, where the fifth on-off valve 69a is closed.

The predetermined time T3 is set to a time necessary for the helium gas concentrations in the second chamber 63 and the chamber 11 to be equal (or a slightly longer time). Therefore, when the predetermined time T3 has elapsed,
The helium gas amount V3 accumulated in the chamber 11 has a value represented by the following equation (9). In Equation 9, the value VC is the volume of the chamber 11.

[0106]

## EQU9 ## V3 = V2.VC / (VB + VC)

As is apparent from Equation 9, the helium gas amount V3 is smaller than the helium gas amount V2, and therefore smaller than the helium gas amount V1. In this manner, a small amount of helium gas suitable for evaluating the highly sensitive leak gas measuring device 10 is accumulated in the chamber 11.

Thereafter, the measurement control device 30 executes step 15
Proceeding to 38 and thereafter, the measurement as the leaked gas measuring device 10 is started. That is, the measurement control device 30 determines in step 154
Proceeding to 0, the timer T is reset and started again, and proceeding to step 1542, the value of the sampling permission flag F is set to "1" and the value of the counter n is set to "1".

As a result, when the measurement control device 30 starts the time interruption routine shown in FIG. 4 at a predetermined timing, the determination in step 405 is “Yes” and the process proceeds to step 410, where the mass spectrometry at that time is performed. Output value L of the vessel 21
Is stored as the measured value L (n) (= L (1)), and the time t at that time is measured as the measurement time t (n) (= t
(1)), and at step 415, the counter n
Is increased by “1”. Thereafter, the measurement control device 30 executes the routine shown in FIG. 4 every time the sampling time TSAMPLE elapses, stores the output value L at that time as the measurement value L (n) in step 410, and The time t is stored as the measurement time t (n), and at step 415, the value of the counter n is incremented by "1".

Referring again to FIG. 15, the measurement control device 30 proceeds to step 1544, and determines whether or not the value of the timer T has become larger than a predetermined time T4 (sec) at step 1544, ie, the timer T is set at step 1540. Then, it is determined whether or not a predetermined time T4 has elapsed after resetting.
When the predetermined time T4 has elapsed, the routine proceeds to step 1546, where the first on-off valve 13 is opened. As described above, the reason why the first opening / closing valve 13 is opened after the predetermined time T4 has elapsed since the closing of the fifth opening / closing valve 69a in the step 1536 is that the measured value L (n) during this period is used. Is used for calculating the background noise.

Next, the measurement control device 30 proceeds to step 154.
In step 1548, it is monitored whether the first on-off valve 13 has been opened based on the output of the valve on-off detection switch 15. When the first opening / closing valve 13 is opened, the valve opening / closing detection switch 15 sends a signal to that effect to the measurement control device 30.
At 548, “Yes” is determined and the process proceeds to step 1550, where the time t at that time is set to the first opening / closing valve opening timing tv
And the process proceeds to step 1552, where the output value L of the mass analyzer 21 at that time is stored as the valve opening output Lv.

Next, the measurement controller 30 proceeds to step 155.
Proceeding to 4, it is determined whether or not the value of the sampling permission flag F has become "0". When the value of the counter n is increased to be equal to the value ne + 1 by execution of step 415 of the routine shown in FIG. 4, the value of the sampling permission flag F is determined as “Yes” in step 420 of the measurement control device 30. Based on the determination, the value is changed to "0" in step 425. The value ne + 1 used in this step 415 is a predetermined time after the sufficient time has elapsed since the first opening / closing valve 13 was opened (the predetermined time after the gas stored in the chamber 11 was supplied to the mass analyzer 21). (Elapsed), the value of the counter n is set to reach.
Therefore, a sufficient number of samplings are performed and the counter n
Is equal to the value ne + 1, the value of the sampling permission flag F is changed to “0”, the measurement control device 30 determines “Yes” in step 1554 of FIG. 15, and proceeds to step 338 and the subsequent steps. Start the analysis.

Since the measurement control device 30 performs substantially the same operation as that shown in FIG. 3 after step 338, the description of each step after step 338 will be omitted. As a result, the total amount LS of the helium gas stored in the chamber 11 is obtained in step 348, and the same value LS is displayed on the display device 31 in step 352. In this case, the above steps 1510 to 1
Since the amount of helium gas accumulated in the chamber 11 by the processing up to 536 is known from the above equations (7), (8) and (9), this amount and the helium gas determined (measured) in step 348 are used. By comparing the amount LS, the measurement accuracy and the like of the device are evaluated.

As described above, according to the evaluation apparatus 60, a known and trace amount of helium gas can be accumulated in the chamber 11 by using the standard leak source 61 having an excessively large leak amount when used as it is. Therefore, it is possible to evaluate the accuracy and the like of the leaked gas measuring device 10.
The evaluation device 60 includes a plurality of standard leak sources 61 and a plurality of serially connected connection pipes 64, 65, 66 between the standard leak sources 61 and the chamber 11 that stores the inspection object. And closed valves 67a, 68a, 6 for opening and closing the plurality of connection pipes 64, 65, 66.
9a, and the on-off valves 67a, 68a, 69a
In a state where the on-off valve 13 is closed, it is possible to accumulate a known and minute amount of helium gas in the chamber 11 by sequentially opening one by one from the side closer to the standard leak source 61 for a predetermined time.

Next, an evaluation device 70 of the leaked gas measuring device 50 according to the second embodiment will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 16 shows a leak gas measuring device 50 and an evaluation device 70 connected to the device.
In the evaluation device 70, regarding the configuration, the second chamber 63 is connected to one end of a fourth connection pipe 71 instead of the third connection pipe 66, and the other end of the fourth connection pipe 71 is connected to the first exhaust pipe 12 Connected between the inspection object S2 and the first on-off valve 13 and the fifth on-off valve 69a is interposed in the fourth connection pipe 71 so as to open and close the passage of the fourth connection pipe 71. The only difference from the evaluation device 60 is that

The evaluation device 70 operates according to the flowchart shown in FIG. Note that steps in FIG. 17 that perform the same processing as the steps shown in FIG. 10 are denoted by the same reference numerals as those shown in FIG. In addition, the gas accumulation in FIG. 17 is started (step 1706).
終了 End (Step 1795) indicates each step of the program executed by the measurement control device 30, and the other steps indicate processes performed by the operator. Further, also in this case, the measurement control device 30 executes the routine shown in FIG. 4 every time the sampling time TSAMPLE elapses.

First, step 1 following step 1700
In step 702, the exhaust device 17 is operated, and in step 17
In step 04, the mass spectrometer 21 is started, and
From 706, processing for accumulating helium gas for evaluation is started. Then, the measurement control device 30 executes step 1
At 708, it is determined whether or not the time required for starting the mass spectrometer 21 has elapsed. If the time required for starting has elapsed, the process proceeds to step 1710, and the first to fifth on-off valves 13, 1 are started.
8, 67a, 68a, and 69a are opened, and the exhaust of the impurity gas existing in all the parts connected to the exhaust device 17 is started.

Next, the measurement control device 30 executes step 1
Proceeding to 712, the output P of the pressure gauge 22 is changed to a predetermined pressure (10
^-2 (Pa)) is determined. When the evacuation proceeds and the output P of the pressure gauge 22 becomes smaller than the predetermined atmospheric pressure, the measurement control device 30 determines in step 1712 that “Y
es ", the process proceeds to step 1714, where the first on-off valve 13, the fourth on-off valve 68a, and the fifth on-off valve 69a are closed, and the standard leak source 61 and the first chamber (first closed chamber) 6 are closed.
Let only 2 be in communication. Next, the measurement control device 3
In step 1716, the timer T is reset and then started. In step 1718, it is determined whether or not the value of the timer T has exceeded a predetermined time T1 (sec).

When the predetermined time T1 has elapsed, the measurement control device 30 determines “Yes” in step 1718, and proceeds to step 1720 to close the third on-off valve 67a. The helium gas amount V1 accumulated in the first chamber 62 during the predetermined time T1 is a value represented by the above equation (7).

Next, the measurement controller 30 proceeds to step 17
Proceeding to 22, the fourth on-off valve 68a is opened. Thereby, the first chamber 62 and the second chamber (second closed chamber) 6
Only 3 is in communication. Next, the measurement control device 3
In step 1724, the process proceeds to step 1724 to reset the timer T and starts. The process proceeds to step 1726 to determine whether or not the value of the timer T is larger than a predetermined time T2 (sec). Step 17 when elapsed
Proceeding to 28, the fourth on-off valve 68a is closed.

The predetermined time T2 is set to a time required for the helium gas concentration in the first chamber 62 and the helium gas concentration in the second chamber 63 to be equal (or a slightly longer time). Therefore, when the predetermined time T2 has elapsed, the helium gas amount V2 accumulated in the second chamber 63 has a value represented by the above equation (8). Steps 1700 to 1728 described above are the same as steps 1500 to 1528 shown in FIG. However,
The predetermined time T1 used in step 1718 is set shorter than the predetermined time T1 used in step 1518. The first chamber 62 in the evaluation device 70
And the volume ratio (VA / VB) of the second chamber 63 is set larger than that of the evaluation device 60. Accordingly, the helium gas amount V2 accumulated in the second chamber 63 at the time when the second predetermined time T2 has elapsed is a minute amount equivalent to the helium gas amount accumulated in the inspection target S2 in the normal measurement. Become.

Thereafter, the measurement control device 30 executes step 17
Proceeding to 30 and thereafter, the measurement as the leaked gas measuring device 50 is started. That is, the measurement control device 30 determines in step 173
In step 2, the fifth on-off valve 69a is opened.
Then, the process proceeds to step 1736 to reset the timer T, and then proceeds to step 1736. At step 1736, the value of the sampling permission flag F is set to "1".
Is set to “1”.

As a result, when the measurement control device 30 starts the time interruption routine shown in FIG. 4 at a predetermined timing, the determination in step 405 is “Yes” and the process proceeds to step 410, where the mass spectrometry at that time is performed. Output value L of the vessel 21
Is stored as a measurement value L (n) (= L (1)), and the time t at that time is measured as a measurement time t (n) (= t (1)).
The value of the counter n is increased by “1” in the following step 415. After this time, every time the sampling time elapses, the output value L at that time is stored as the measured value L (n), and the time t at that time is stored.
Is stored as the measurement time t (n), and the value of the counter n is incremented by “1”.

Referring again to FIG. 17, the measurement control device 3
If it is 0, the process proceeds to step 1738 to determine whether or not the value of the timer T is greater than a predetermined time T4 (sec). When the predetermined time T4 has elapsed, “Yes” is determined in step 1738.
The process proceeds to step 1740 and proceeds to step 174.
At 0, the first on-off valve 13 is opened. As described above, the reason why the first opening / closing valve 13 is opened after the lapse of the predetermined time T4 since the opening of the fifth opening / closing valve 69a in step 1732 is that one of the measured values L (n) during this period is used. This is because the unit is used for calculating the background noise.

Next, the measurement control device 30 executes step 174.
The program then proceeds to step 1742, where it monitors whether the first on-off valve 13 has opened based on the output of the valve on-off detection switch 15. When the first opening / closing valve 13 is opened, the valve opening / closing detection switch 15 sends a signal to that effect to the measurement control device 30.
At 742, “Yes” is determined, and the process proceeds to step 1744, where the time t at that time is set to the first opening / closing valve opening timing tv.
At step 1746, the output value L of the mass analyzer 21 at that time is stored as the valve opening output Lv.

Next, the measurement controller 30 proceeds to step 174.
Proceeding to 8, it is determined whether the value of the sampling permission flag F has become "0". When the value of the counter n is increased to be equal to the value ne + 1 by execution of step 415 of the routine shown in FIG. 4, the value of the sampling permission flag F is determined as “Yes” in step 420 of the measurement control device 30. Based on the determination, the value is changed to "0" in step 425. The value ne + 1 used in this step 415 is determined by the fact that a sufficient time has elapsed since the first opening / closing valve 13 was opened (in this case, after the gas stored in the second chamber 63 is supplied to the mass analyzer 21). , A predetermined time has elapsed), the value of the counter n is set to reach. Therefore, when a sufficient number of samplings are performed and the value of the sampling permission flag F is changed to “0”, the measurement control device 30 determines “Yes” in step 1748 of FIG. Proceed and start analyzing the data.

Since the measurement control device 30 performs substantially the same operation as that shown in FIG. 10 (FIG. 3) after step 338, the description of each step after step 338 will be omitted. As a result, the total amount LS of the helium gas stored in the second chamber 63 is obtained in step 348, and the same value LS is displayed on the display device 31 in step 352.
Is displayed. In this case, the processing from step 1710 to step 1728 causes the second chamber 63
Since the amount of helium gas accumulated in the device is known from the above equations (7) and (8), the accuracy of the apparatus is evaluated by comparing this amount with the helium gas amount LS obtained in step 348. Is done.

As described above, according to the evaluation device 70, a known and trace amount of helium gas is accumulated in the second chamber 63 by using the standard leak source 61, which leaks too much when used as it is. Therefore, it is possible to evaluate the leaked gas measuring device 50.

Next, a leak gas measuring device 80 according to a third embodiment of the present invention shown in FIG. 18 will be described. The leaked gas measuring device 80 includes a cooling device 81 added to the chamber 11 of the leaked gas measuring device 10 of the first embodiment, and the impurity gas other than the gas to be measured (helium gas in this case) existing in the chamber 11. The amount of gas is reduced, and the detection sensitivity is further improved.

FIG. 19 shows the relationship between temperature and vapor pressure for each gas. As is clear from FIG. 19, when the chamber 11 is cooled by liquid nitrogen having a temperature of 70K,
Helium gas to be measured has a vapor pressure of 70
Since K is sufficiently large, it exists as a gas in the chamber 11 (the vapor pressure of helium gas does not decrease). On the other hand, gases such as carbon dioxide (CO ₂ ) and water (H ₂ O), which are often contained as impurity gases, have a vapor pressure of 10 ⁻⁷ (Pa) or less at a temperature of 70 K, which is sufficiently small. Therefore, by cooling the chamber 11 with liquid nitrogen,
Impurity gas other than helium gas can be selectively exhausted (in this case, adsorbed on the inner wall surface of the chamber 11). Therefore, the leak gas measuring device 80 used liquid nitrogen as a cooling medium. However, methane (CH ₄ ),
Since oxygen (O ₂ ) has a relatively large vapor pressure at a temperature of 70 K, it takes time to exhaust these gases by cooling the chamber 11 with liquid nitrogen.
Therefore, when a large amount of these impurity gases are contained and it is necessary to shorten the evacuation time, it is desirable to use liquid helium as a cooling medium.

Referring again to FIG. 18, the chamber 11 of the leaked gas measuring device 80 has a hollow cylindrical shape,
It has flange portions 11a and 11b on the bottom and top surfaces. The bottom side flange portion 11a is the same as the bottom side flange portion 1
The lid 1c is closed by a lid 11c detachably fixed to the bolt 1a. The upper surface side flange portion 11b is closed by a lid 11d which is detachably bolted to the upper surface side flange portion 11b. The first exhaust pipe 1 is provided at the center of the lid 11d.
2 are connected at one end. Thereby, the chamber 11
The gas existing inside is exhausted to the mass analyzer 21 side along the axial direction of the chamber 11.

The cooling device 81 of the leaked gas measuring device 80
A cylindrical cooling body 82, a liquid nitrogen tank 83 for storing liquid nitrogen, and a cooling pipe 84 for supplying the liquid nitrogen in the liquid nitrogen tank 83 to the surface of the cooling body 82
A cooling pump 85 interposed in the cooling pipe 84;
A temperature sensor 86 that detects the temperature in the chamber 11 and outputs the same temperature TEMP. The other configuration is the same as that of the leaked gas measuring device 10, so that the same portions are denoted by the same reference numerals and description thereof will be omitted. The temperature sensor 86 is mounted on the inner wall surface of the chamber 11 and connected to the measurement control device 30. If it is difficult to mount the temperature sensor 86 on the inner wall surface of the chamber 11, the temperature sensor 86 may be mounted on the outer side wall surface of the chamber 11.

The cooling main body 82 has a substantially cylindrical main body portion 82a made of a metal such as copper having a high thermal conductivity and in contact with the side wall surface of the chamber 11 to cover the same. The main body 82a is divided into two parts, and is attached to the chamber 11 by a plurality of bolts 82c penetrating through the flanges 82b provided on the main bodies 82a.

The cooling pipe 84 is made of a metal such as copper having a high thermal conductivity. Both ends of the cooling pipe 84 communicate with the liquid nitrogen tank 83, and a cooling section meandering while contacting the surface of the main body 82a of the cooling main body 82 is provided. Have. This cooling pipe 84
Is provided with a connecting portion 84a at a position near the chamber 11, and when the cooling main body 82 is removed from the chamber 11, the cooling main body 82 is divided into two parts by the connecting portion 84a, and the cooling main body 82 is removed from the chamber 11 It is configured to enable.

The cooling pump 85 is connected to the measurement control device 30 and operates based on a command signal from the measurement control device 30 so that the liquid nitrogen in the liquid nitrogen tank 83 passes through the cooling pipe 84 through the cooling pipe 84. The power is supplied to the main body 82 a of the cooling main body 82.

Next, the operation of the leak gas measuring device 80 configured as described above will be described with reference to FIG. In FIG. 20, steps that perform the same processing as the steps illustrated in FIG. 3 are denoted by the same reference numerals as those illustrated in FIG. The start of measurement (Step 2002) to the end (Step 2095) indicate each step of the program executed by the measurement control device 30,
The other steps show the steps performed by the operator. Furthermore,
Also in this case, the measurement control device 30 executes the routine shown in FIG. 4 every time the sampling time TSAMPLE elapses.

First, step 3 following step 2000
At 02, a known pressure (for example, 1
00 (Pa)) helium gas. Next, the inspection object S1 is set in the chamber 11 in step 304, and the chamber 11 is closed in step 306 (the lid 1).
The chamber 11 is sealed (with 1c fixed to the chamber 11). At this stage, the measurement start button (not shown) is operated, and the measurement control device 30 starts the processing after step 2002.

The measurement control device 30 operates the exhaust device 17 in step 2004, and opens the first and second on-off valves 13 and 18 in step 2006. As a result, the discharge of the impurity gas existing in each part including the chamber 11 and connected to the exhaust device 17 is started. Next, the measurement control device 30 proceeds to step 2008, in which the first opening / closing valve 13 is heated to about 150 ° C. for a predetermined time by a heating device (not shown), and thereafter, baking for providing a cooling period for a predetermined time is performed. This step 2008 can be omitted.

When the processing in step 2008 is completed
(At the end of the cooling period), the measurement control device 30
Proceeding to step 2010, the output P of the pressure gauge 22 is
(10 ^-2(Pa)) to determine whether it is less than
When the output P of the output 22 becomes lower than the predetermined pressure,
Step 20 is determined as "Yes" at Step 2010.
Then, in step 2012, the first on-off valve 13 is turned on.
Close.

Next, the measurement control device 30 proceeds to step 20.
Proceeding to 14, the time t at that time is stored as the helium gas accumulation start time t0. Thereafter, the measurement control device 30
Is started after resetting the timer T in step 2016, and in step 2018, it is determined whether or not the timer T has counted a predetermined time (helium gas accumulation guarantee time) TS0. This predetermined time TS0 is necessary for the helium gas sealed in the substantially enclosed space of the inspection target S1 to leak from the inspection target S1 into the chamber 11 and be accumulated in an amount required for measurement. Time, for example, tens of minutes
Hundreds of hours.

Next, the measurement control device 30 executes step 202
In step 2022, the mass spectrometer 21 is started.
To operate the cooling pump 85 to start cooling the chamber 11 with liquid nitrogen. Note that step 202
A step 1508 shown in FIG. 15 may be inserted between 0 and the step 2022 to confirm that the activation of the mass spectrometer 21 is completed. Next, the measurement control device 30
Is the temperature TE indicated by the temperature sensor 86 in step 2024.
By determining whether MP has become lower than the predetermined temperature TE0, it is determined whether or not the chamber 11 has been sufficiently cooled by liquid nitrogen.

When the chamber 11 is sufficiently cooled by the liquid nitrogen, the measurement control device 30
Is determined to be "Yes", the process proceeds to step 2026, and the timer T is reset and started. Next, the measurement control device 30 determines whether or not the timer T has counted a predetermined time (emission guarantee time) Tα in step 2028,
Step 2 until the timer T counts a predetermined time Tα.
028 is repeatedly executed.

The guaranteed evacuation time Tα is such that the chamber 11 is cooled by liquid nitrogen, and impurity gases other than helium gas remaining in the chamber 11 are exhausted (in this case, adsorbed on the inner wall surface of the chamber 11). Is the time needed to The exhaust guarantee time Tα is, for example, several minutes to several tens of minutes, and is set to be shorter than the helium gas accumulation guarantee time TS0. In other words, the flow rate of the cooling pump 85 and the cooling pipe 84 are determined so that the impurity gas is sufficiently exhausted even when the time Tα is short. Thus, it is possible to avoid a characteristic change due to the overcooling of the inspection target S1.

After the evacuation guarantee time Tα has elapsed, the measurement control device 30 determines “Yes” in step 2028 and proceeds to step 2030, resets and starts the timer T, and then starts sampling in step 2032. The value of the flag F is set to “1”, and the value of the counter n is set to “1”.

As a result, when the measurement control device 30 starts the time interruption routine shown in FIG. 4 at a predetermined timing, the determination in step 405 is “Yes” and the process proceeds to step 410, where the mass spectrometry at that time is performed. Output value L of the vessel 21
Is stored as the measured value L (n) (= L (1)), and the time t at that time is measured as the measurement time t (n) (= t
(1)), and in the next step 415, the value of the counter n is increased by "1". Hereinafter, the measurement control device 3
0 executes the routine shown in FIG. 4 every time the sampling time TSAMPLE elapses. At step 410, the output value L at that time is stored as a measurement value L (n), and the time t at that time is set to the measurement time The value of the counter n is incremented by “1” at step 415.

Referring again to FIG. 20, measurement control device 3
If it is 0, the process proceeds to step 2034. In step 2034, it is determined whether or not the value of the timer T is greater than a predetermined time T4 (sec), that is, whether or not the predetermined time T4 has elapsed after resetting the timer T in step 2030. Is determined. When the predetermined time T4 has elapsed, the routine proceeds to step 2036, where the first on-off valve 13 is opened. The reason why the first opening / closing valve 13 is opened after waiting for the predetermined time T4 after the elapse of the exhaust gas assurance time Tα is that a part of the measured value L (n) during this period is set in the background. This is for use in calculating noise.

Next, the measurement control device 30 executes step 203
In step 2038, it is monitored whether the first on-off valve 13 has been opened based on the output of the valve on-off detection switch 15. When the first opening / closing valve 13 is opened, the valve opening / closing detection switch 15 sends a signal to that effect to the measurement control device 30.
At 038, "Yes" is determined, and the routine proceeds to step 2040, where the time t at that time is set to the first opening / closing valve opening timing tv.
The process proceeds to step 2042, and the output value L of the mass analyzer 21 at that time is stored as the valve opening output Lv.

Next, the measurement control device 30 executes step 204
Proceeding to 4, it is determined whether or not the value of the sampling permission flag F has become "0". When the value of the counter n is increased to be equal to the value ne + 1 by execution of step 415 of the routine shown in FIG. 4, the value of the sampling permission flag F is determined as “Yes” in step 420 of the measurement control device 30. Based on the determination, the value is changed to "0" in step 425. The value ne + 1 used in this step 415 is a predetermined time after the sufficient time has elapsed since the first opening / closing valve 13 was opened (the predetermined time after the gas stored in the chamber 11 was supplied to the mass analyzer 21). (Elapse), the value of the counter n is set to reach. Therefore, when a sufficient number of samplings are performed and the value of the sampling permission flag F is changed to “0”, the measurement control device 30 determines “Yes” in step 2044 in FIG. 20 and proceeds to step 2046. .

The measurement controller 30 stores the time obtained by subtracting the helium gas accumulation start time t0 from the first on-off valve opening time tv in step 2046 as the (helium gas) accumulation time TS. Then, the operation of the cooling pump 85 is stopped to end the cooling of the chamber 11, and then the process proceeds to step 338 and thereafter to start the data analysis.

Since the measurement control device 30 performs substantially the same operation as that shown in FIG. 3 after step 338, the description of each step after step 338 will be omitted. As a result, the measurement control device 30 determines the flow rate Lout of the helium gas leaking from the inspection target S1 in step 350 using the accumulation time TS determined in step 2046. The above is the operation of the leak gas measuring device 80 when measuring the leak gas amount.

FIG. 21 is a flowchart showing steps 302 and 30 of the steps shown in FIG.
Step 4 is omitted, that is, in a state where the inspection object S1 is not arranged in the chamber 11, steps 306 to 306 are performed.
The output of the mass spectrometer 21 obtained when executing all the steps up to the step 2095 (when measuring after cooling by the cooling device 81) (curve L1 in FIG. 21)
And the output of the mass spectrometer 21 obtained when executing the steps from Steps 306 to 2095 omitting Steps 2022 to 2028 (measured without cooling by the cooling device 81). (Figure 2
1 shows a time change of a curve L2). Note that FIG.
In FIG. 1, time tv indicates the valve opening timing of the first on-off valve 13.

As is clear from FIG. 21, when cooling with liquid nitrogen is not performed before the measurement (curve L2), since the impure gas is measured by the mass analyzer 21, the first on-off valve 13 is opened. A waveform having a steep peak was measured immediately after the valve. On the other hand, when cooling with liquid nitrogen was performed before the measurement (curve L1), the peak as seen in the curve L2 was not measured. This indicates that the impurity gas in the chamber 11 is adsorbed on the inner wall of the chamber 11 and does not appear as noise during measurement.

When the measurement is performed after cooling by the cooling device 81, the mass spectrometer 2
The first output L decreases with time after the first on-off valve 13 is opened (after time tv) because the first on-off valve 13 opens to the mass analyzer 21 (for example, This is because the impurity gas existing in the first exhaust pipe 12, the second exhaust pipe 16 and the like is adsorbed on the inner wall surface of the chamber 11. However, such a change due to the adsorption is recognized as background noise due to step 346 and the like described in the first embodiment, and thus does not affect the detection accuracy of the leaked gas measuring device 80 at all.

Table 1 is based on the assumption that the measurement shown in FIG. 21 described above measured only helium gas, and the helium gas flow rate Lout (see step 350) obtained at that time was converted into an equivalent standard leak amount. It is indicated by a value. In other words, Table 1 indicates that an impurity gas corresponding to the equivalent standard leak amount shown in Table 1 is measured as helium gas.

[0155]

[Table 1]

According to Table 1, when the resolution in the case where the cooling was not performed before the measurement is “1”, the resolution in the case where the cooling is performed before the measurement is “26” (= 2.9 × 10−). 16 /
1.1 × 10−17). That is, the leak gas measuring device 80 can detect up to 1/26 of the minimum leak amount of helium gas detectable by the leak gas measuring device 10 and has extremely high detection accuracy. Is understood.

FIG. 22 shows an example in which the evaluation device 60 shown in FIG. 14 is connected to the leak gas measuring device 80 in a state where impurity gases other than helium gas are sufficiently exhausted, and the same measurement as shown in FIG. (Cooling by the cooling device 81 and when the cooling was not performed) are performed, and the amount of helium in the chamber 11 at that time (known from the above equations 7 to 9) and the leakage gas measuring apparatus 80 are used. It shows the relationship with the measured helium amount LS. As can be understood from FIG. 22, the presence or absence of cooling by the cooling device 81 does not affect the amount (concentration) of helium gas in the chamber 11 at all. That is, since the amount of the helium gas to be measured does not change due to the mounting of the cooling device 81, it is understood that the leakage gas measuring device 80 has high detection accuracy also in this sense.

By repeating the process of cooling the chamber 11 with the cooling device 81 to adsorb the impurity gas into the chamber 11 many times, the impurity gas and organic matter (dirt) are deposited on the inner wall surface of the chamber 11. They adhere in large quantities, appear as impurity gases during measurement, and may reduce the measurement accuracy of the leaked gas measuring device 80. On the other hand, since the cooling device 81 (cooling main body 82) is configured to be detachable from the chamber 11, the cooling device 81 can be removed at an appropriate timing after performing suction by the cooling device 81 a plurality of times. Is removed from the chamber 11, a heater (a ribbon heater made of a nichrome wire or the like) is attached to the chamber 11, the chamber 11 is heated to, for example, 100 ° C. or more, and the exhaust device 17 is operated to evacuate the inside of the chamber 11 to, for example, 10 mm. ^By setting the degree of vacuum to about ⁻² (Pa), it is possible to remove impurity gas and organic substances attached to the inner surface of the chamber 11 (so-called baking). By doing so, the leakage gas measuring device 80
Can maintain high detection accuracy.

In the leak gas measuring device 80, when the inspection object S1 is replaced, etc.
To the atmosphere. Chamber 1 of leak gas measuring device 80
1 is cooled down to a very low temperature during measurement,
When the chamber 11 is opened to the atmosphere, the temperature of the chamber 11 and the atmospheric temperature may greatly differ. In this case, a large amount of moisture in the atmosphere adheres to the inner surface of the chamber 11, so that the chamber 11 will not be used in the next and subsequent measurements.
The moisture attached to the inner wall of the device evaporates, and the detection accuracy of the device is reduced.

In order to cope with this, the detected temperature TEMP of the temperature sensor 86 provided in the leaked gas measuring device 80 is always displayed on the display device 31 so that the chamber 11 is opened to the atmosphere and the temperature of the chamber 11 is changed to a large amount of the moisture adhering. After confirming that the temperature has risen to a level that does not cause the above-mentioned problem In this case, the worker controls the opening of the chamber 11 to the atmosphere by visually checking the display device 31. However, an electromagnetic lock or the like for controlling the opening of the chamber 11 is provided, and Only when the temperature has risen sufficiently, an instruction may be given from the measurement control device 30 to the electromagnetic lock to release the restriction on the opening of the chamber 11.

As described above, in the leak gas measuring device 80, the impurity gas is removed by cooling the chamber 11 in which the helium gas is stored with liquid nitrogen before the start of the measurement.
Therefore, the detection accuracy is further improved. Also, the cooling device 81
Can be removed and the chamber 11 can be baked, and high detection accuracy can be maintained.

In the leak gas measuring device 80, since the chamber 11 has a cylindrical shape and a very simple shape, the leak in the chamber 11 itself can be minimized. Since the number of welding points and connection points in the chamber 11 can be reduced, the probability of occurrence of leakage from the welding points and connection points can be maintained at a low value. In addition, since the shape of the chamber 11 is cylindrical and the direction of taking out the leaked gas is set in the axial direction of the chamber 11, the resistance (exhaust resistance) at the time of taking out the leaked gas can be reduced. As a result, the entire gas accumulated in the chamber 11 reaches the mass analyzer 21 in a short time, so that the peak value of the output L of the mass analyzer 21 is larger than the resolution of the mass analyzer 21. It can be a value. As a result, the accuracy of measuring the amount of leaked gas can be increased.

When the chamber 11 is cooled, the inspection object S1 is also cooled at the same time, and there is a possibility that the characteristics of the inspection object S1 change or the amount of gas leakage from the inspection object S1 changes. is there. In such a case, FIG.
As shown in each of FIGS. (A) to (D), a portion that is not directly cooled by liquid nitrogen (a portion that is not shaded in each of FIGS. Base part 91a fixed to a part which is not cooled down, and an arm part 91b extending from the base end part 91a
And a holding member 91 having a shelf 91c connected to the tip of the arm 91b and enabling the inspection object S1 to be placed. In this case, the arm 9
By setting the length of 1b as long as possible, it is effective to reduce the temperature drop of the shelf 91c due to the heat conduction from the chamber 11.

The cooling structure of the cooling device 81 is shown in FIG.
28 to 28 may be modified. To explain these modifications, the cooling structure shown in FIG. 24 has a structure in which a metal tube made of copper or the like having high thermal conductivity is wound around the chamber 11 and liquid nitrogen is passed through the metal tube. It is.

The cooling structure shown in FIG.
A structure in which a plurality of cooling fins 93 made of a metal having a high thermal conductivity are joined to the side wall surface of the chamber, and the chamber 11 and the cooling fins 93 are housed in a container 94 that is airtight and has good heat insulation. It is. Liquid nitrogen is injected into the container 94, and the liquid nitrogen becomes gaseous and fills the container 94, thereby cooling the chamber 11 through the cooling fins 93. The container 94 may be filled with liquid nitrogen.

In the cooling structure shown in FIG. 26, a metal tube 95 made of copper or the like having a high thermal conductivity is spirally wound, the wound portion is disposed in the chamber 11, and In this structure, liquid nitrogen is supplied from the outside of the chamber 11 to the portion where the liquid nitrogen is supplied. In this case, the impurity gas in the chamber 11 is adsorbed on the metal tube 95.

In the cooling structure shown in FIG. 27, a rod-shaped metal 96 made of copper or the like having a high thermal conductivity is wound along the side wall of the chamber 11, and both ends of the rod-shaped metal 96 are thin plates 97 made of the same kind of metal. And the thin plate 97 is immersed in a container 98 filled with liquid nitrogen. Thus, the metal plate 97 is cooled by the liquid nitrogen, which cools the rod-shaped metal 96 by heat conduction, and the rod-shaped metal 96 cools the chamber 11.

The cooling structure shown in FIG.
The chamber 11 is inserted into a container 100 having a cylindrical shape having an inner diameter (diameter) LY larger than the diameter LC of the flange portions 11a and 11b and having upper and lower surfaces opened. 11
Are closed by ring-shaped lid members 101 and 102 made of a material having compressive properties and heat insulating properties. In this case, the ring-shaped lid members 101, 10
2 is detachable from the container 100. Further, a pair of through holes 103 and 104 penetrating the side wall of the container 100 are provided at the upper part of the container 100, and liquid nitrogen is injected from the through hole 103, and the inside of the container 100 is filled with the liquid nitrogen. It is filled. In addition, the through-hole 104 functions as a vent hole from liquid nitrogen.

According to the structure shown in FIG.
1 can be directly cooled with liquid nitrogen, so that the inner wall of the chamber 11 can be easily cooled to a low temperature.
Further, the ring-shaped lid members 101 and 102
Since the diameter LC of the flange portions 11a and 11b of the chamber 11 is smaller than the inner diameter LY of the container 100, the chamber 11 can be removed from the container 100. Thereby, the chamber 11 can be taken out of the container 100, and a heater can be attached to the chamber 11 to perform the above-described baking in which the chamber 11 is overheated.

As described above, according to the embodiments of the present invention, it is possible to obtain the leak gas measuring devices 10, 50, and 80 having extremely high detection sensitivity. In addition, it is possible to obtain evaluation devices 60 and 70 that can evaluate the measurement accuracy of these leak gas measurement devices 10, 50 and 80.

Note that the present invention is not limited to the above embodiment, and can be implemented in various modes within the scope of the present invention. For example, in each of the above embodiments, in order to reduce degassing and reduce background noise, each on-off valve such as the first on-off valve 13 is a metal valve,
The gasket used between the first on-off valve 13 and the chamber 11 may be a copper gasket. The evaluation device 60
, The standard leak source 61 may be directly connected to the chamber 11 for a predetermined time, and the evaluation device 70 may be configured to directly connect the standard leak source 61 to the first exhaust pipe 12 for a predetermined time. . Furthermore, although the on-off valves such as the first to fifth on-off valves 13, 18, 67a, 68a, 69a and the like are of the electromagnetic type, it is also preferable to use pneumatic on-off valves that can open and close in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic view of a leakage gas measuring device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of the mass spectrometer shown in FIG.

FIG. 3 is a flowchart showing steps of a leak gas measurement by the leak gas measuring device shown in FIG.

FIG. 4 is a flowchart showing a time interruption routine executed by a measurement control device of the leaked gas measurement device shown in FIG.

FIG. 5 is a schematic sectional view of the inspection object shown in FIG. 1;

FIG. 6 is a graph showing measurement results of the leak gas measuring device shown in FIG.

FIG. 7 is a graph for explaining a background estimation method by the leak gas measuring device shown in FIG. 1;

FIG. 8 is a graph for explaining calculation of a leak gas amount by the leak gas measuring device shown in FIG. 1;

FIG. 9 is a schematic diagram of a leak gas measuring device according to a second embodiment of the present invention.

FIG. 10 is a flowchart showing a process of leak gas measurement by the leak gas measuring device shown in FIG. 9;

11 is a graph showing the total amount of leaked gas measured when the leak gas measuring device shown in FIG. 9 changes the accumulation time of leaked gas.

FIG. 12 is a graph showing a change in the output of the mass analyzer when the accumulated helium gas gradually reaches the mass analyzer shown in FIG. 1 or 9;

FIG. 13 is a graph showing a change in the output of the mass analyzer shown in FIG. 1 or FIG. 9 when the accumulated helium gas quickly reaches the mass analyzer.

FIG. 14 is a schematic view of a leak gas measuring device shown in FIG. 1 and an evaluation device connected to the leak gas measuring device.

FIG. 15 is a flowchart showing steps for evaluating the leaked gas measuring device by the evaluation device shown in FIG.

FIG. 16 is a schematic diagram of the leak gas measuring device shown in FIG. 9 and an evaluation device connected to the leak gas measuring device.

FIG. 17 is a flowchart showing steps for evaluating the leaked gas measuring device by the evaluation device shown in FIG.

FIG. 18 is a schematic view of a leakage gas measuring device provided with a cooling device according to a third embodiment of the present invention.

FIG. 19 is a graph showing the relationship between temperature and vapor pressure for various gases.

20 is a flowchart showing a process of measuring a leaked gas by the leaked gas measuring device shown in FIG. 18;

FIG. 21 shows a case where the measurement is performed without cooling the chamber in a state where the inspection object is not installed in the leak gas measuring apparatus illustrated in FIG. 18 and a case where the measurement is performed after the chamber is cooled. 6 is a graph showing the time change of the output of the mass spectrometer obtained in the case where the output is obtained.

FIG. 22 shows a case in which the leak gas measuring device shown in FIG. 18 is connected to the evaluation device shown in FIG. 14 in a state where the impurity gas is sufficiently exhausted, and the measurement is performed without cooling the chamber. It is a graph which shows the amount of leakage gas (helium gas) measured in the case where measurement was performed after cooling.

FIGS. 23A to 23D are views showing the inside of a chamber of the leaked gas measuring device shown in FIG. 18;

24 is a view showing a modification of the cooling structure of the chamber of the leak gas measuring device shown in FIG.

25 is a diagram showing another modification of the cooling structure of the chamber of the leak gas measuring device shown in FIG.

26 is a diagram showing another modification of the cooling structure of the chamber of the leak gas measuring device shown in FIG.

FIG. 27 is a view showing another modification of the cooling structure of the chamber of the leaked gas measuring device shown in FIG.

FIG. 28 is a view showing another modification of the cooling structure of the chamber of the leak gas measuring device shown in FIG.

FIG. 29 is a schematic view of a conventional leak gas measuring device.

[Explanation of symbols]

10 ... leakage gas measuring device, 11 ... chamber, 12 ... first
Exhaust pipe, 13: first on-off valve, 14: on-off valve driving device, 1
5: valve open / close detection switch, 16: second exhaust pipe, 17: exhaust device, 18: second open / close valve, 19: open / close valve driving device, 2
0: third exhaust pipe, 21: mass analyzer, 22: pressure gauge, 3
0: measurement control device, 31: display device, 32: recording device,
S1: Inspection object.

Continued on the front page (72) Inventor Motohiro Fujiyoshi 41-cho, Yokomichi, Nagakute-machi, Aichi-gun, Aichi Prefecture Inside of Toyota Central Research Laboratory Co., Ltd. No. 1 Inside Toyota Central Research Laboratories Co., Ltd. (72) Inventor Yoshiteru Omura Yoshikichi Omura 41, Oku-cho, Yoji, Nagakute-cho, Aichi-gun Aichi Pref. 41 in the Toyota Central R & D Laboratories Co., Ltd. (72) Inventor Jiro Sakata F-term in the Toyota Central R & D Laboratories Co., Ltd. (reference) 2F030 CC13 CF05 CF08 2G067 AA24 CC13 DD04 DD06

Claims (19)

[Claims] 1. A method of measuring a leaked gas for measuring an amount of gas leaking from an inspection object having a substantially sealed space in which a predetermined gas is enclosed, the method comprising: Exhausting the interior of the chamber through an exhaust passage connected to the chamber containing the object, and closing the exhaust passage connected to the chamber for a predetermined time to leak from the inspection target into the chamber A method of measuring a leaked gas, comprising: a step of accumulating the gas; and a step of measuring a total amount of the accumulated gas after a lapse of the predetermined time. 2. The method for measuring a leaked gas according to claim 1, wherein before the step of measuring the total amount of the accumulated gas, adsorption of an impurity gas other than the predetermined gas existing in the chamber is performed. A method for measuring leaked gas comprising an impurity gas adsorption step to be started. 3. The leak gas measuring method according to claim 2, wherein the impurity gas adsorption step is a step of cooling the chamber. 4. A leak gas measuring method for measuring an amount of gas leaking from the outside to the inside of an inspection object having a substantially closed space in order to determine the airtightness of the inspection object, wherein the inspection object is housed. Supplying the gas into the chamber that has been set, exhausting the test object through an exhaust passage connected to the test object, and setting the exhaust passage connected to the test object for a predetermined time. Only accumulating the gas leaking from the chamber into the inspection object from the chamber, and measuring the total amount of the accumulated gas after the lapse of the predetermined time. Leak gas measurement method. 5. The method for measuring a leaked gas according to claim 1, wherein the step of measuring the total amount of the accumulated gas comprises: transmitting the accumulated gas to a flow rate measuring device. A method for measuring a leaked gas, comprising: a supplying step; and a step of integrating a value corresponding to an output of the flow rate measuring device. 6. The leak gas measuring method according to claim 5, further comprising: estimating a background noise having the same output based on an output of the flow measuring device, and a value corresponding to an output of the flow measuring device. Is a step of integrating a value obtained by subtracting the estimated background noise from an output of the flow measurement device as a value corresponding to the output of the flow measurement device. 7. The leak gas measuring method according to claim 6, wherein the step of estimating the background noise is performed within a predetermined period before and after a period during which the accumulated gas is supplied to the flow rate measuring device. A method for measuring a leaked gas, which is a step of estimating the background noise based on an output of the flow rate measuring device. 8. The method for measuring a leaked gas according to claim 1, wherein a total amount of the measured gas is divided by the predetermined time to reduce a flow rate of the leaked gas. A method for measuring a leaked gas, comprising a step of obtaining a corresponding amount. 9. A chamber for accommodating an inspection object, a flow measurement device, an exhaust passage connecting between the chamber and the flow measurement device, and an exhaust passage interposed between the exhaust passage and opening and closing the exhaust passage. An on-off valve to be closed, and a measurement control device, wherein the measurement control device closes the on-off valve, closes the chamber for a predetermined time, and leaks from the test object into the chamber. Leak gas accumulating means for accumulating gas to be generated, and opening and closing the on-off valve after the lapse of the predetermined time, supplying the accumulated gas to the flow rate measuring device, and integrating a value corresponding to the output of the flow rate measuring device. And an integrating means for measuring the total amount of the accumulated gas. 10. The leak gas measuring device according to claim 9, further comprising: an exhaust device connected to the exhaust passage between the on-off valve and the flow rate measuring device. Exhaust control means for opening the on-off valve and driving the exhaust device to exhaust the inside of the chamber before the leak gas accumulation means starts accumulating gas leaking from the inspection object. Leak gas measurement device. 11. The leak gas measuring device according to claim 9, further comprising an adsorbing means for adsorbing an impurity gas other than the gas present in the chamber. . 12. The leak gas measuring apparatus according to claim 11, wherein said adsorption means includes a cooling means for cooling said chamber. 13. The leak gas measuring apparatus according to claim 12, wherein the measurement control unit starts the operation of the cooling unit before measuring the total amount of the accumulated gas by the integrating unit. A leak gas measuring device comprising cooling control means for cooling a chamber. 14. A gas supply system comprising: a chamber to which a predetermined gas is supplied; a flow measurement device; an exhaust passage connecting between an inspection target housed in the chamber and the flow measurement device; An on-off valve installed and closed to open and close the exhaust passage, and a leak gas measurement device including a measurement control device, wherein the measurement control device closes the on-off valve to seal the inspection object for a predetermined time, Leak gas accumulating means for accumulating the predetermined gas leaking into the inspection object; opening and closing the on-off valve after the lapse of the predetermined time, supplying the accumulated gas to the flow rate measuring device, An integrating means for integrating a value corresponding to the output of the measuring device to measure the total amount of the accumulated gas. 15. The leak gas measuring device according to claim 9, wherein said measuring control means divides the total amount of said gas obtained by said integrating means by said predetermined time. And a flow rate calculating means for calculating a flow rate of the leaked gas. 16. The evaluation device for a leak gas measuring device according to claim 9, wherein a standard leak source having a known amount of leak of the predetermined gas per unit time is provided. A connection passage connecting the standard leak source to the chamber or a closed chamber communicating with the chamber; an opening / closing valve interposed in the connection passage to open and close the connection passage; and an opening / closing interposed in the exhaust passage. An opening device for opening a switching valve interposed in the connection passage for a predetermined time in a state where the valve is closed, and an evaluation device for the leaked gas measuring device. 17. The evaluation device for a leak gas measuring device according to claim 9, wherein the sealed gas chamber stores a predetermined amount of the predetermined gas, and the sealed gas chamber. A connection passage connecting the air passage and the chamber; an opening / closing valve interposed in the connection passage to open and close the connection passage; and an opening / closing valve interposed in the exhaust passage closed through the connection passage. A valve opening means for opening the mounted on-off valve until the gas concentration in the closed chamber becomes equal to the gas concentration in the chamber. 18. The evaluation device for a leak gas measuring device according to claim 14, wherein a standard leak source having a known leak amount of the predetermined gas per unit time, the standard leak source and the exhaust passage are provided. A connection passage connecting a portion between the on-off valve and the inspection object or a closed chamber communicating with the portion, an on-off valve interposed in the connection passage and opening and closing the connection passage; Valve opening means for opening the on-off valve interposed in the connection passage for a predetermined time while the on-off valve interposed in the exhaust passage is closed. Evaluation device. 19. The evaluation device for a leak gas measuring device according to claim 14, wherein: the first closed chamber storing the predetermined gas having a known gas amount; and the on-off valve being the exhaust passage. A second closed chamber connected to a portion between the inspection object, a connection passage connecting the first closed chamber and the second closed chamber, and a connection passage interposed in the connection passage to open and close the connection passage A gas concentration in the first closed chamber and a gas concentration in the second closed chamber with the on / off valve interposed in the exhaust passage being closed while the on / off valve interposed in the connection passage is closed. An evaluation device for a leaked gas measuring device, comprising a valve opening means for opening a valve until the pressures become equal to each other.