JPH07272671A - Method and device for gas analysis - Google Patents

Abstract

PURPOSE:To enhance the sensing sensitivity and measure a small quantity of impurities simply by installing an ion source and a quadripolar tube individually to an envelope, and separating the two by a bulkhead. CONSTITUTION:A gas analyzing device is structured so that a bulkhead means 6 having an orifice is installed inside of an envelope 5 to partition the inside into two vacuum chambers. The first vacuum chamber 25 is fitted to an ion source 1 while the second vacuum chamber 26 is equipped with a quadripolar tube 2 and an electron multiplier tube 3. When a pressure difference is generated between the two chambers 25, 26, ions produced by the ion source 1 move to the second chamber 26. The ions having passed the tube 2 are sensed by the sensing part of the multiplier tube 3, and the composition of impurity gas contained by the gas existing in a chamber 8 is analyzed. According to this constitution, the second vacuum chamber 26 will not be contaminated with the gas to be measured, and the quadripolar tube 2 is prevented from adsorption of the gas to be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas analyzer using a quadrupole mass spectrometer.

[0002]

2. Description of the Related Art Generally, in order to form a thin film by sputtering, vapor deposition, etc., it is necessary to place a substrate to be film-formed in a vacuum atmosphere. It is known that not only the degree of vacuum has an influence, but also the composition of the residual gas in it has a great influence.

In order to analyze the composition of such residual gas, a gas analyzer has been conventionally used. Among them, the one using a quadrupole mass spectrometer is convenient for maintenance and handling. Because of its high measurement accuracy, it is widely used from research fields to production fields.

FIG. 2 shows a conventional gas analyzer using a quadrupole mass spectrometer.

The gas analyzer 110 comprises an ion source 101,
A quadrupole mass analysis tube having a quadrupole tube 102 and an electron multiplier tube 103 as a detection device is provided, and the quadrupole mass analysis tube is mounted on a base flange 104 and housed in an envelope 105. . The envelope 105 is connected to a turbo molecular pump 109 so that the gas inside can be exhausted to reach a high vacuum.

The envelope 105 is connected via a stop valve 107 to a vacuum container 108 of a device to be measured such as a sputtering device or a vapor deposition device, and the inside of the envelope 105 is desired by the turbo molecular pump 109. After being placed in a vacuum atmosphere, the stop valve 1
07 is opened, the gas in the vacuum container 108 is introduced into the envelope 105, and the ion source 101
Is ionized into ions to be introduced into the quadrupole tube 102, and only the DC voltage applied to the quadrupole tube 102 and the ions having a mass corresponding to the frequency of the AC voltage are multiplied by the electron multiplier. It is arranged so that it can reach the tube 103 and measure its partial pressure.

Generally, a quadrupole mass spectrometer tube is
The gas pressure in the atmosphere in which it is placed is 1 × 10 ^-2 P
If it is not in a high vacuum atmosphere such as a or less, it cannot operate normally. In particular, the quadrupole tube 10
If the mean free path in 2 is short, the ions passing through the quadrupole tube 102 collide with other gases and disappear, so that the partial pressure cannot be accurately measured. . For this reason, it is generally said that it is desirable to measure in a high vacuum state at a pressure of 1 × 10 ⁻³ Pa or less.

On the other hand, among vacuum devices for which gas analysis is desired, there are many devices such as a sputtering device which operate in a state where the degree of vacuum inside the chamber is about 10 ^-1 Pa or higher. In such a case, the quadrupole mass spectrometer cannot be operated by directly introducing the sputter gas into the envelope 5. Therefore, in the conventional gas analyzer 110, the stop valve 107 and the envelope 105 are not provided. An orifice device 106 is provided between the chamber 1 and the chamber 1 through the orifice of about 1 mm provided in the orifice device 106.
08 is configured to introduce the gas in the envelope 105 to secure the pressure difference between the chamber 108 and the envelope 105,
The inside is kept at a predetermined degree of vacuum.

By the way, in the envelope 105,
Since the probe 111 of the ionization vacuum system is provided, the pressure inside the envelope 105 can be measured.
Specifically, if the turbo molecular pump 109 is operated with the stop valve 107 closed, the degree of vacuum in the envelope 105 can reach a range of 10 ⁻⁶ to 10 ⁻⁵ Pa. , The envelope 10
If degassing treatment such as baking is applied to 5, 10 ^-7 Pa
It is possible to reach the high vacuum region of.

Then, in this state, the stop valve 1
When opening 07, gas is introduced from the chamber 108 into the envelope 105, so that the inside of the envelope 105 exhibits a pressure of about 10 ⁻⁴ to 10 ⁻³ Pa.

Before and after the operation of the stop valve 107, that is, the mass spectrum when the stop valve 107 is closed and the mass spectrum when the stop valve 107 is opened are recorded, and the stop valve 107 is recorded. By subtracting the mass spectrum when the stop valve 107 is closed from the mass spectrum in the open state, the mass spectrum of the gas inside the chamber 108, which is the system to be measured, can be detected. Therefore, the smaller the residual gas inside the quadrupole mass spectrometer tube when the stop valve 107 is closed, that is, the smaller the mass spectrum at that time, the more the gas inside the chamber 108 is introduced when the gas is introduced. It will be possible to detect even trace amounts of components.

Specifically, the ultimate pressure (total pressure) when the stop valve 107 is closed is set to 1 × 10 ^-6 Pa, the pressure when the stop valve 107 is opened and the gas in the chamber 108 is introduced. Is 1 × 10 ⁻³ Pa, the detection limit of the composition of the gas introduced at this time will be described.

In the vacuum system of such a gas analyzer 110, the inner surface of the envelope 105, the material forming the quadrupole mass spectrometer tube, or the ion source 10 is used.
There are various released gases, such as the gases released from 1 and the like. The composition of these released gases is mainly a partial pressure of 10
^-7 and Pa range of H _2, H ₂ O, the partial pressure 10 ^-8 to 10 ^-7 Pa range, CH _4, CO, it contains a gas such as CO ₂ have been known. Then, when the partial pressures of these released gases are summed up, a background state in which the stop valve 107 is closed, that is, a total pressure of the vacuum system of the gas analyzer 110 itself of 1 × 10 ⁻⁶ Pa is almost shown. Becomes Therefore, these released gases become the background gas, and their partial pressures become the background spectrum of this gas analyzer.

For the vacuum system having such a background spectrum, the stop valve 1
When 07 is opened and the gas in the chamber 108 is introduced, the spectrum of the introduced gas is superimposed on the background spectrum.

Generally, the detection sensitivity of the measuring device is S
/ N ratio, but here, attention is paid to each component of the released gas in the background state, the detection sensitivity for each component, the partial pressure of each component of the background gas as the numerator. The S / N ratio of each component is represented by the denominator of the pressure (total pressure) when the stop valve 7 is opened and gas is introduced. And
Assuming that the detection limit for each component of the background gas is when the S / N ratio is 1, the minimum detection partial pressure of each component of the background gas is H ₂ and H ₂ O is several 100 p.
It is understood that pm and other background gas components remain at several tens of ppm, and even partial pressures lower than this cannot be detected, so they are not sufficient for film quality control.

It is known that a large amount of such background gas is generated from the vicinity of the ion source 101. This is because the heat generated by the filament of the ion source 101 is supported by the filament or the wiring. It is thought to be due to the fact that the material is transmitted and the surrounding area is heated. On the other hand, the amount of the background gas released due to the gas released from the ion source 101 can be measured by cooling the envelope 105 after baking the envelope 105 for a sufficient time to release the adsorbed gas sufficiently. For example, it is possible to reduce the total pressure to a high degree of vacuum of the order of 10 ⁻⁷ Pa.

However, even if the degree of vacuum is reduced to a high degree by baking or the like, the stop valve 10 is then used.
When 7 is opened and the gas in the chamber 108 is introduced into the envelope 105 and measurement is performed, the gas is adsorbed to the quadrupole mass spectrometer tube or the probe 111. In particular, the quadrupole mass spectrometer tube has the ion source 101, the quadrupole tube 102, and the electron multiplier tube 103, and has a large surface area, so that a large amount of gas is adsorbed to this.

When such adsorption occurs, even when the stop valve 107 is closed again thereafter, the ultimate vacuum degree is deteriorated to the order of 10 ^-6 Pa due to the release of the adsorbed gas, and the ultimate vacuum immediately after baking is 10 ° ^{C. It} does not recover to ⁷ Pa level. Then, even if the gas in the chamber 108 is introduced in this state and the measurement is started again, only the inaccurate measurement result can be obtained because the detection sensitivity is lowered.
Trace amount of impurity gas contained in (argon gas) is ppm
We were unable to measure quantities below the order.

Further, since the filament provided in the ion source 101 is broken when it is used for a long time, maintenance is required to replace it, and when the ion source 101 is used for a long time, the electrodes are contaminated. Maintenance such as cleaning and replacement of various parts is required.
When performing such maintenance work, the ion source 10
1 had to be disassembled, and the work was troublesome.

[0020]

The present invention has been made in view of the disadvantages and inconveniences of the above-mentioned conventional techniques, and its purpose is high detection sensitivity, which does not decrease detection sensitivity even when gas introduction is repeated, and An object of the present invention is to provide a gas analyzer that can easily measure impurities in the ppm order or less and that can be easily maintained.

[0021]

In order to solve the above-mentioned problems, the invention apparatus according to claim 1 introduces a gas to be measured into an ion source and ionizes the gas introduced by the ion source to generate ions. Generated, introduced the ions into the quadrupole tube, selectively pass according to its mass number and charge, the ions that have passed through the quadrupole tube are detected by a detection device and the composition of the gas to be measured. In the gas analyzer for analyzing, the ion source is arranged in a first vacuum chamber, the quadrupole tube and the detector are arranged in a second vacuum chamber, and the first vacuum chamber and the second vacuum chamber are arranged. 3. The invention according to claim 2, wherein the partition wall means having an orifice is used to separate the space between the first and the second vacuum chambers from the first vacuum chamber through the orifice. The apparatus is the gas analyzer according to claim 1, wherein 4. The invention device according to claim 3, wherein the first vacuum chamber is connected to a first vacuum pump which is one exhausting means, and the second vacuum chamber is connected to a second vacuum pump which is another exhausting means. Is the gas analyzer according to claim 1 or 2, wherein the ion source is provided with degassing means, and the invention apparatus according to claim 4 is characterized in that 5. The gas analyzer according to claim 5, wherein the ion source and the quadrupole tube are insulated from each other, and the inventor according to claim 5 is the gas analyzer according to claim 1. A probe of a vacuum gauge is provided in the second vacuum chamber, and the invention apparatus according to claim 5 is the gas analyzer according to any one of claims 1 to 5, wherein the ion source is dedicated. Attached to the flange, the ion source can be detached together with the dedicated flange Characterized in that attached to the serial first vacuum chamber.

According to the seventh aspect of the present invention, the gas to be measured is introduced into an ion source, the gas is ionized by the ion source to generate ions, and the ions are introduced into a quadrupole tube. In a gas analysis method of selectively passing according to a mass number and an electric charge, detecting the passed ions with a detector to analyze the composition of the gas to be measured, an atmosphere in which the ion source is placed, and The atmosphere in which the quadrupole tube and the detection device are placed is evacuated by different vacuum pumps, and the ions generated by the ion source are introduced into the quadrupole tube to analyze the composition of the gas to be measured. The invention method according to claim 8 is characterized in that a gas to be measured is introduced into an ion source, the gas is ionized by the ion source to generate ions, and the ions are introduced into a quadrupole tube to generate a mass number. And selectively pass according to the charge, pass In the gas analysis method of detecting the ions with a detection device and analyzing the composition of the gas to be measured, the ion source is arranged in a first vacuum chamber, and the quadrupole tube and the detection device are arranged in a second vacuum chamber. The second vacuum chamber and the second vacuum chamber are provided with a pressure difference so that the degree of vacuum of the second vacuum chamber is higher than that of the first vacuum chamber. The composition is characterized in that the ions generated by the ion source are introduced into a vacuum chamber to analyze the composition of the gas to be measured.

[0023]

[Function] When the gas to be measured is introduced into the ion source, the introduced gas is ionized by the ion source to generate ions, and the ions are introduced into the quadrupole tube, the voltage applied to the quadrupole tube is changed. Since ions having a corresponding mass number and electric charge can be selectively passed, if the ions passing through the quadrupole tube are detected by a detector such as an electron multiplier, the composition of the gas to be measured will be Can be analyzed.

At this time, the ion source is arranged in the first vacuum chamber, the quadrupole tube and the detection device are arranged in the second vacuum chamber, and the first vacuum chamber and the second vacuum chamber are arranged. If the spaces are separated by partition means having an orifice, a pressure difference can be provided so that the degree of vacuum in the second vacuum chamber is higher than that in the first vacuum chamber, and the orifice causes the pressure difference. Since the ions are introduced from the first vacuum chamber to the second vacuum chamber via the above, the second vacuum chamber is not contaminated with the high-concentration gas.

Further, the first vacuum chamber is connected to a first vacuum pump which is one exhausting means, and the second vacuum chamber is connected to a second vacuum pump which is another exhausting means. 1
If the measurement target gas is introduced into the vacuum chamber, a pressure difference can be provided between the first vacuum chamber and the second vacuum chamber, and the measurement target introduced into the first vacuum chamber. The high-concentration gas, which is a gas, is exhausted by the first vacuum pump and does not enter a large amount into the second vacuum chamber. Further, even when the degassing means provided in the ion source releases the adsorbed gas from the ion source, the released gas is exhausted by the first vacuum pump, so that the second vacuum chamber is not contaminated.

Furthermore, if the ion source and the quadrupole tube are insulated, the quadrupole tube is not unnecessarily heated by the heat generated by the ion source. In addition, the quadrupole tube does not generate unnecessary emission gas, and measurement with low background noise can be performed.

If a gauge head of a vacuum gauge is provided in the second vacuum chamber, the gas adsorbed by the gauge head will not be released, so that measurement with less background noise can be performed. .

If the ion source is attached to a dedicated flange detachably attached to the first vacuum chamber, the ion source can be removed together with the dedicated flange. Easy removal of the ion source.

[0029]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the device of the present invention.

Reference numeral 10 denotes a gas analyzer, which introduces a gas to be measured such as argon gas (Ar) existing in the chamber 8 of the sputtering apparatus, ionizes it by ionization, and introduces the ions. A quadrupole tube 2 for selectively passing the ions according to their mass number and electric charge,
An electron multiplier 3 which is a detection device for detecting ions passing through the quadrupole tube 2 is provided, and the signal output from the electron multiplier 3 is amplified and processed by an electronic circuit (not shown) to perform the measurement. The composition of the target gas is analyzed.

The quadrupole tube 2 and the electron multiplier tube 3 are mounted on a base flange 4 and attached to an envelope 5. On the other hand, the ion source 1 has a filament 21 and a grid 22 (anode) therein,
The filament 21 and the grid 22 are attached to the flange 12. The flange 12 is detachably attached to the envelope 5, and when the flange 12 is removed, the ion source 1 having the filament 21 and the grid 22 is also removed, and the replacement is made. Easy to work.

As described above, the ion source of the conventional gas analyzer is directly attached to the quadrupole tube, and the heat generated by the ion source is transferred to the quadrupole tube. The ion source 1 and the quadrupole tube 2 are separately attached to the envelope 5, and both of them are arranged separately. Therefore, the heat generated by the ion source 1 is not transferred to the quadrupole tube 2 but transferred from the filament 21 to the envelope 5 and is radiated by the envelope 5 having a large surface area. The cathode 2 and the electron multiplier 3 are not unnecessarily heated, and the amount of released gas is reduced.

Further, since the filament 21 and the grid 22 can be exchanged together with the flange 12 by removing the flange 12 from the envelope 5, the exchange time when the filament 21 is broken is short. As a result, the operating efficiency of the gas analyzer 10 can be improved.

Inside the envelope 5, partition means 6 having an orifice with a diameter of 3 mm is provided to separate into a first vacuum chamber 25 and a second vacuum chamber 26, and the ions are stored in the first vacuum chamber 25. Since the source 1 is arranged and the quadrupole tube 2 and the electron multiplier tube 3 are arranged in the second vacuum chamber 26, a pressure difference is provided between the first vacuum chamber 25 and the second vacuum chamber. When a constant electric field is applied, the ions generated in the ion source 1 move from the first vacuum chamber to the second vacuum chamber through the orifice, and the quadrupole tube 2 Ions that have passed through are detected by the detector of the electron multiplier 3.

This pressure difference can be obtained by connecting the first vacuum chamber 25 and the second vacuum chamber 26 to a vacuum pump by pipes having different conductances, but in this embodiment, it is 50 L. 2 with a pumping speed of / s
Two turbo molecular pumps are prepared, and the first vacuum chamber 25 and the second vacuum pump 9b are used as the first vacuum chamber 25 and the first vacuum chamber 25, respectively.
Is connected to the second vacuum chamber 26, and the internal gas of both vacuum chambers can be individually exhausted. According to this structure, when the degree of vacuum in the first vacuum chamber 25 is 5 × 10 ⁻² Pa, the degree of vacuum in the second vacuum chamber 26 is 2.5 × 10 ⁻⁴ P.
It is maintained at a, and a pressure difference of two digits or more is generated. At this degree of vacuum, the mean free path inside the quadrupole tube 2 is sufficiently long that ions do not collide with other gases. The gas does not reduce the ion passing efficiency. Since the quadrupole tube 2 selectively passes, among the ions, one having a mass number and a charge corresponding to the AC voltage and the DC voltage applied to the quadrupole tube 2,
This is detected by the electron multiplier 3 and the composition of the impurity gas contained in the sputtering gas in the chamber 8 is analyzed.

Further, according to this structure, the gas to be measured introduced into the first vacuum chamber 25 is the first vacuum pump 9
Since it is exhausted by a and does not enter the second vacuum chamber 26, the second vacuum chamber 26 may be contaminated with the measurement target gas, or the measurement target gas may be adsorbed to the quadrupole tube 2 having a large surface area. Can be prevented.

In order to measure the degree of vacuum and the total pressure of the gas to be measured, the probe 11 of the ionization vacuum gauge is used as the second probe.
Since it is attached to the vacuum chamber, the gas emitted from the probe 11 is ionized by the ion source, the ionized gas is detected, and the background noise does not increase. The two turbo molecular pumps are each connected to a fore pump, and are configured to discharge the gas in the vacuum chamber into the atmosphere.

Further, since the first vacuum chamber 25 is constructed to be as small as possible so that the ion source 1 can be housed therein, the exhaust efficiency of the first vacuum pump 9a is increased and the ultrahigh vacuum is easily achieved. Can be put in a state. Also, the first
Since the inner surface area of the vacuum chamber 25 that can be adsorbed by the gas becomes small, workability such as easy recovery to the initial state even after introducing the measurement gas in the chamber 8 and performing measurement, A highly responsive measurement can be performed.

Further, since the ion source 1 is provided with a degassing means for applying an electron impact to release the adsorbed gas,
By activating the first vacuum pump 9a and operating the degassing means, the gas adsorbed by the ion source 1 can be degassed and exhausted to the outside of the first vacuum chamber. The amount of gas released from the source 1 is reduced, and measurement of low background noise can be performed. In addition, it is particularly effective to perform the degassing process after the flange 12 is replaced or when a highly accurate measured value is required. Since a heater (not shown) is wound around the envelope 5, the heater is energized to bake the envelope 5 and the first vacuum pump 9
By operating a and the second vacuum pump 9b, the gas adsorbed on the entire inner surface of the envelope 5 can be released and exhausted to the outside of the vacuum chamber, so that the measurement of the background noise can be further reduced. it can.

Since such degassing treatment can be performed, the first vacuum chamber 25 and the second vacuum chamber 26 are ^separated by 1 × 10 ^−7.
It is possible to easily reach a vacuum degree of a pressure of Pa or less. Moreover, when this degassing treatment is performed, 90% or more of the residual gas composition becomes H ₂ , and CH ₄ , H ₂ O, CO, C
The residual gas component that greatly affects the film quality such as O ₂ is 10 ⁻
Reduce to partial pressures below ⁹ Pa. Then, this becomes the composition of the background gas and the partial pressure of each component gas that constitutes the background gas. Since the partial pressure value of each component gas that constitutes the background gas is small in this way, for example, when a gas of 5 × 10 ^-2 Pa is introduced into the first vacuum chamber, an S / N ratio of 1 is detected. Even as a limit, several hundred p of each component gas that constitutes the background gas is used.
It is possible to measure up to pb order.

After the above degassing treatment was performed, when the energization of the heater was stopped, it was observed that the pressure indicated by the ionization vacuum gauge gradually decreased. Then, when the degree of vacuum of the ionization vacuum gauge reaches the level of 10 ⁻⁸ Pa,
The stop valve 7 connected to the chamber 8 was opened, and the gas to be measured in the chamber 8 was introduced into the first vacuum chamber 25. At this time, the sputtering apparatus having the chamber 8 was executing a sputtering process, and the pressure in the chamber 8 was in a medium vacuum state of about 10 ^-1 Pa. However, in consideration of the balance between the conductance of the stop valve 7 and the conductance of the pipe, and the size of the exhaust speed of the first vacuum pump, the pressure in the first vacuum chamber 25 is 5 × 10 ⁻² Pa or less. there were. As described above, since the vacuum pump is directly provided in the first vacuum chamber 25 in which the ion source 1 is arranged to exhaust the gas therein, as shown in FIG. 2, the orifice device 106 is provided in front of the ion source. There is no need to place.

FIG. 3 shows an example of actual measurement of the composition of the impurity gas contained in the argon gas of the apparatus of the present invention.

When this measurement was carried out, the chamber 8 was evacuated to a vacuum degree of the order of 10 ^-7 Pa, a variable leak valve (not shown) was opened, and high-purity argon gas was introduced into the chamber 8 for internal measurement. Pressure is 5 × 10 ^-1 Pa
Raised to. The envelope 5 was baked with the heater (not shown) of the gas analyzer, and the first vacuum pump 9a and the second vacuum pump 9b were operated to evacuate the ion source 1 to degas it. At this time,
The degree of vacuum indicated by the ionization vacuum gauge having the probe 11 was in the order of 10 ⁻⁸ Pa.

The horizontal axis of the graph shown in FIG. 3 is time, and the unit of the scale is seconds. The vertical axis is the ion current value
Since it is (A) and the scale is a logarithmic scale, the numbers 8 to 13 described on the left side of the vertical axis represent the index of the ion current value. More specifically, for example, between the numeral 8 and the numeral 9, 10 ⁻⁹ A and between the numeral 12 and the numeral 13 are 10 ⁻¹³ A ion current values. And in general, the concentration ratio of each component gas that constitutes the measurement target gas is proportional to the ratio of this ion current value,
As shown on the right side of the vertical axis in the figure, if the ionic current value is known, it can be converted into the concentration and the composition of each component of the gas to be measured can be measured.

Each broken line in the graph shown in FIG. 3 indicates a mass number of 36 ( ³⁶ Ar) and a mass number of 28 (CO or N, respectively).
₂ ), mass number 44 (CO ₂ ), mass number 18 (H ₂ O), mass number 32 (O ₂ ), and shows the change over time in the ion current value. Since the stop valve 7 is closed, the background spectrum of the gas analyzer 10 is shown, and during this period, the current value indicating CO or N ₂ is about 2.5.
X 10 ^-12 A can only be detected, H ₂ O, O ₂ , ³⁶ Ar,
Almost no CO ₂ was detected, indicating that a normal atmosphere was achieved.

When 600 seconds have passed, the stop valve 7 is opened, and the high purity A is removed from the chamber 8.
r gas was introduced. At this time, the gas having the highest pressure is argon gas ( ⁴⁰ Ar) having a mass number of 40. However, in order to prevent overrange, ³⁶ Ar of the isotopes of Ar is used here.
Is recorded, and shows 5 × 10 ⁻⁹ A within 1200 seconds. Generally, ³⁶ Ar
^{Since the} natural abundance ratio to ⁴⁰ Ar is 3400 ppm, ³⁶ Ar recorded here also corresponds to a concentration ratio of approximately 3400 ppm with respect to the total amount of gas introduced into the ion source.

On the other hand, during 600 seconds to 1200 seconds, H ₂ O, CO or N ₂ , O ₂ , CO ₂ together with ³⁶ Ar.
Since the ion current value of 1 is slightly increased, it can be seen that these gases are mixed as impurities in the Ar gas. This CO or N ₂ is about 8 ppm, CO ₂ is about 700
ppb, H ₂ O is about 600 ppb, O ₂ is about 400 ppb
It is understood that it becomes possible to measure an extremely small amount of impurity gas as compared with the conventional method.

Further, when the stop valve 7 was closed at 1200 seconds, it was found that the ion current value of the impurity gas was rapidly decreased and the background spectrum before the introduction of the argon gas was returned to after that. It can be seen that the impurity gas is adsorbed in the vacuum chamber and is gradually released, which does not adversely affect the subsequent measurements.

Although the turbo molecular pump is used as the exhaust pump in the above embodiment, a turbo drag pump,
It is possible to use various pumps such as a cryopump or an ion pump that can obtain an ultrahigh vacuum. If the pressure in the chamber 8 is particularly high, an appropriate orifice, needle valve or the like may be attached in the middle of the pipe for introducing the measurement gas.

Further, although the partition means 6 is provided with an orifice having a diameter of 3 mm, it is sufficient that this orifice has a suitable differential pressure and does not interfere with the ion trajectory. It is not limited.

Further, if it is desired to accurately measure the pressure in the first vacuum chamber 25, a total pressure gauge such as an ionization vacuum gauge may be attached to the first vacuum chamber 25. However, care must be taken when the total pressure gauge generates the released gas.

[0053]

According to the present invention, since the impurity gas is less adsorbed, the background noise can be measured with a small amount, and the composition of a trace amount of gas contained in the gas to be measured can be detected.

Further, the initial state can be easily restored, and the measurement with good responsiveness can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional gas analyzer.

FIG. 3 An example of actually measuring the composition of an impurity gas contained in argon gas

[Explanation of symbols]

1 ... Ion source 2 ... Quadrupole tube 3 ...
… Detection device 4 …… Base flange 5 …… Envelope
6 ... Partition means 7 ... Stop valve 8 ... Chamber 9a ... First vacuum pump 9b ... Second vacuum pump 11 ... Ionization gauge gauge 12 ... Flange 21 ... Filament 22 ... Grid 25 ...... First vacuum chamber 26 …… Second vacuum chamber

Claims (8)

[Claims] 1. A gas to be measured is introduced into an ion source, the gas introduced by the ion source is ionized to generate ions, and the ions are introduced into a quadrupole tube, and the ions are responsive to the mass number and charge thereof. In the gas analyzer that detects the ions that have passed through the quadrupole tube with a detector and analyzes the composition of the gas to be measured, the ion source is arranged in a first vacuum chamber, and The quadrupole tube and the detection device are arranged in a second vacuum chamber, the first vacuum chamber and the second vacuum chamber are separated by a partition means having an orifice, and the first vacuum chamber is separated via the orifice. A gas analyzer configured to introduce the ions from a vacuum chamber into the second vacuum chamber. 2. A first evacuation means for the first vacuum chamber
The gas analyzer according to claim 1, wherein the gas analyzer is connected to a vacuum pump, and the second vacuum chamber is connected to a second vacuum pump which is another evacuation unit. 3. The gas analyzer according to claim 1, wherein the ion source is provided with degassing means. 4. The gas analyzer according to claim 1, wherein the ion source and the quadrupole tube are thermally insulated. 5. The gas analyzer according to claim 1, wherein a probe of a vacuum gauge is provided in the second vacuum chamber. 6. The ion source is attached to a dedicated flange, and the ion source is detachably attached to the first vacuum chamber together with the dedicated flange. Gas analyzer. 7. A gas to be measured is introduced into an ion source, the gas is ionized by the ion source to generate ions, and the ions are introduced into a quadrupole tube and selectively selected according to mass number and charge. In the gas analysis method of analyzing the composition of the gas to be measured by detecting the passed ions with a detection device, the atmosphere in which the ion source is placed, the quadrupole tube and the detection device are A gas analysis method, comprising: evacuating a placed atmosphere with a vacuum pump different from the placed atmosphere, introducing ions generated by the ion source into the quadrupole tube, and analyzing the composition of the measurement target gas. 8. A gas to be measured is introduced into an ion source, the gas is ionized by the ion source to generate ions, and the ions are introduced into a quadrupole tube and selectively selected according to mass number and charge. In the first vacuum chamber, wherein the ion source is arranged in a first vacuum chamber, and the quadrupole tube and the detection device are used. Is provided in the second vacuum chamber, a pressure difference is provided between the second vacuum chamber and the second vacuum chamber so that the degree of vacuum of the second vacuum chamber is higher than that of the first vacuum chamber, and the first vacuum chamber is provided. A gas analysis method, comprising introducing ions generated by the ion source from a vacuum chamber into the second vacuum chamber and analyzing the composition of the gas to be measured.