JPH0660847A - Ion source for atmospheric pressure ionization mass spectrometer and its discharge needle positioning device - Google Patents

Abstract

PURPOSE:To perform the movement adjustment of the discharge needle of the ion source of an atmospheric pressure ionization mass spectrometer with discharge completed. CONSTITUTION:This ion source of an atmospheric pressure ionization mass spectrometer is provided with a discharge needle 10 performing ionization by discharging to gas which is the object for mass spectrometry. In a main body 13, in which the casing of the ion source is formed; the discharge needle 10 is joined to the tip of a micrometer 14, fixed to the main body 13, via an insulating insulator 11, and the tip part of the micrometer 14 is covered by a bellows 12 for keeping airtightness. The electrification to the discharge needle 10 is made through the side wall of the main body 13 and the movement of the discharge needle 10 is made by operating the rotation control of the micrometer 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique relating to an ion source of an atmospheric pressure ionization mass spectrometer, and more particularly to a technique which is effectively used for adjusting movement of a discharge needle in a short time.

[0002]

2. Description of the Related Art With the miniaturization of semiconductor devices, it is required to increase the purity of process gas used for processing. An atmospheric pressure ionization mass spectrometer is used as the gas measuring device in this case. This atmospheric pressure ionization mass spectrometer is composed of an atmospheric pressure ionization section, a mass analysis section and a detection section. At the time of measurement, the gas introduced under the condition of 1 atm in the atmospheric pressure ionization section is discharged and ionized, and the ions and neutral molecules generated at that time are introduced into the mass spectrometric section in the vacuum state, and the detection section The ionic strength is detected, and analysis is performed based on the relationship between the ionic strength and the mass number known in advance.

The atmospheric pressure ionization section is disclosed in, for example, Japanese Patent Laid-Open No. Sho 60.
No. 100352, the configuration thereof is, as shown in FIG. 4, provided with an opening in the side wall of the ion source block 1,
A discharge needle 2 having a sharp tip is attached to this opening via an insulator 3. Furthermore, in the ion source block 1,
A groove portion 4 having an inverted triangular convex portion is provided on the bottom so as to surround the opening, and the insulator 3 is fixed to the groove portion 4. The ion source block 1 is slidable in the groove 4
A groove portion 5 is provided in the longitudinal direction. One end of the ion source block 1 is connected to the housing 6 of the mass spectrometric section, and an opening is formed in a portion of the connection section facing the ion source block 1, and this opening forms a counter electrode 7 for the discharge needle 2. ing.

In this configuration, the ion source block 1
When the gas to be analyzed is introduced from the direction of arrow A in the figure and a high voltage is applied between the discharge needle 2 and the counter electrode 7, corona discharge is generated around the tip of the discharge needle 2 and the gas around the It is ionized, and a part thereof is sent into the housing 6 through the opening of the counter electrode 7 and further sent to a mass spectrometric section (not shown). The state of corona discharge depends on the type of gas, the tip position of the discharge needle 2, the shape of the tip, the applied voltage, etc., and the groove 4 is slid along the groove 5 in order to perform good discharge. Make adjustments.

[0005]

According to the study by the present inventor, the above-mentioned prior art requires the adjustment of moving the discharge needle (the operation of changing the distance between the discharge needle and the counter electrode) according to the type of gas. However, the adjustment must be performed by loosening the fixing screw and it is dangerous because the high voltage is applied. Therefore, the discharge must be stopped while the discharge needle is moving. Further, since the ion source is held at a high temperature of 100 to 200 ° C., it is necessary to wait until the ion source drops to room temperature when moving the discharge needle, and after moving the discharge needle, wait a long time until the temperature reaches high temperature. There is the problem of having to do it. Also, when moving the discharge needle, the atmospheric pressure component (especially water) is easily adsorbed from the groove and the sliding part of the groove into the ion source, and it takes time to remove it, so move the position of the discharge needle. There is also a problem that it takes a long time to restart the analysis.

Therefore, an object of the present invention is to provide a technique capable of adjusting the movement of the discharge needle while the discharge is being performed.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, an ion source of an atmospheric pressure ionization mass spectrometer equipped with a discharge needle for ionizing a gas to be subjected to mass analysis by electric discharge, wherein an insulation is provided in a main body forming a casing of the ion source. Holding means arranged in a state, an energizing means for supplying power to the discharge needle from outside the ion source, and a driving means for moving the holding means forward and backward in the length direction of the discharge needle. .

[0010]

According to the above means, the power supply and the movement can be performed with the discharge needle sealed in the ion source, and the movement of the discharge needle can be adjusted without stopping the operation of the ion source. Therefore, the position adjustment of the discharge needle can be set in a short time, and the change of gas type can be easily dealt with.

[0011]

Embodiment 1 FIG. 1 is a front sectional view showing an embodiment of an ion source of an atmospheric pressure ionization mass spectrometer according to the present invention.

A partition wall with the mass spectrometric section functions as a counter electrode 8, and a discharge needle 10 is arranged so as to face a pinhole 9 provided in the counter electrode 8. The discharge needle 10 is held by an insulator 11 (holding means) for electrically insulating the discharge needle 10 from other members, and the insulator 11 is attached to the tip of a bellows 12 (holding means).

The bellows 12 is fixed to the center of a metal main body 13 having a U-shaped cross section. In addition,
The rear end of the bellows 12 is fixed to the main body 13. A micrometer 14 (driving means) is attached so as to be exposed from the main body 13, and the bellows 12 expands and contracts (forwards and backwards) in the length direction of the needle according to the rotation amount and the rotation direction of the rotary knob. Further, a heater 15 is embedded in the main body 13 so that the main body 13 is kept in a high temperature atmosphere.
A thermocouple 16 is embedded adjacent to the heater 15 in order to control the temperature of the water so that the water content in the inside can be removed.

A gas supply port 17 and a gas exhaust port 18 for supplying and discharging gas into and from the body 13 are provided above and below the tip of the discharge needle 10. An opening is provided adjacent to the gas supply port 17, and an insulator 19 is provided in the opening.
A (hermetic seal) is enclosed, and a cable 20 connected to the discharge needle 10 is inserted through the center of the insulator 19. An O-ring 21 is provided at the connecting portion between the counter electrode 8 and the main body 13 to seal the two.

In the above structure, the inside of the main body 13 is kept at 100 to 200 ° C. by the heater 15 and the thermocouple 16. In this state, gas (for example,
Nitrogen, argon, silane, etc.) are introduced and then the cable 20 is powered. Here, when the adjustment knob of the micrometer 14 is rotated to the left or right, the bellows 12 expands and contracts (with this, the tip of the bellows 12 moves the discharge needle 10 of the micrometer 14 forward and backward, and An optimum discharge state can be obtained in a short time (for example, 1 minute as compared with the conventional one hour) by adjusting the distance from the pinhole 9. During this adjusting operation, power supply to the discharge needle 10 is stopped. There is no need, and the heater 15 may be kept operating.

[0016]

Second Embodiment FIG. 2 is a front sectional view showing a second embodiment of the ion source of the atmospheric pressure ionization mass spectrometer according to the present invention.

The present embodiment is characterized in that a straight advancing machine 22, which is an application of a micrometer, is used as a drive source for moving the discharge needle 10 forward and backward. This straight ahead introduction machine 22
Is integrally provided with a mounting plate 22a having airtightness, and the mounting plate 22a is directly mounted on the main body 13. For this purpose, the main body 13 is provided with an opening on the mounting surface of the straight-advance introduction machine 22, and the drive end portion of the straight-advance introduction machine 22 can be inserted through this opening. An O-ring 23 for preventing gas leakage is arranged between the mounting plate 22a and the mounting surface of the main body 13. The discharge needle 10 is attached to the drive end of the straight advancement machine 22 via a rod-shaped insulator 24.

In this embodiment, the rotary knob provided at the end of the straight advancing machine 22 is rotated in the same manner as in the above-mentioned embodiments, so that the insulator 24 and the discharge needle are discharged in accordance with the direction and amount of rotation. 10 moves forward and backward, the distance between the counter electrode 8 and the discharge needle 10 changes, and the optimum discharge position can be determined in a short time.

[0019]

[Embodiment 3] FIG. 3 is a block diagram showing a discharge needle positioning device of an ion source of an atmospheric pressure ionization mass spectrometer according to the present invention.

The present embodiment controls the motor 25 for rotating the rotary knob of the straight advancing machine 22 based on the ion detection result in the configuration of FIG. Motor 25
Is mounted on the mounting plate 22a of the straight advancing machine 22 by the motor fixing base 26
Is fixed through. As described above, the right side of the counter electrode 8 shown in the figure is the mass spectrometric section, and the inside is evacuated. A quadrupole mass spectrometer 27 is arranged in the mass spectrometer, and the ionized gas from the counter electrode 8 is fed into the quadrupole mass spectrometer 27.

A voltage in which a direct current voltage and a high frequency voltage are superimposed is applied to the electrode portion of the quadrupole mass spectrometer 27, and the ionized gas sent between the electrodes is mass-separated (separated by the voltage application state). ), And the amount of ions is detected by the ion detector 28. The relationship between the ion intensity and the mass number can be graphed based on the detection result and the mass separation result, and this state is displayed on a display device (not shown). The calculation processing unit 29 calculates whether the discharge needle 10 should be moved forward or backward based on the intensity of the detected ion amount by the ion detector 28. Based on the result of this calculation, the motor drive circuit 30 is driven to rotate the motor 25 in the forward direction or the reverse direction. This rotation causes the discharge needle 1
When 0 is moved forward or backward and the discharge condition reaches the optimum position (the detection value by the ion detection unit 28 is the maximum), the control of the motor 25 is stopped. By such control, the positioning of the discharge needle 10 can be automated, and the adjustment time can be shortened while performing the adjustment accurately. It also enables automatic switching of gas types.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in the above-mentioned embodiment, the seal between the member for moving the discharge needle forward and backward and the main body is performed by the bellows 12 or the straight advance introducer 22, but instead of this, a member for moving the discharge needle forward and backward is used. It can also be configured to be attached to the main body via an O-ring.

Further, in the above-mentioned embodiment, the discharge needle is moved by using the micrometer 14 which is the driving means or the straight advancing device 22, but conversely, the holding means is fixed to the main body side, and the main body side is fixed. May be moved.

[0025]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, an ion source of an atmospheric pressure ionization mass spectrometer equipped with a discharge needle for ionizing a gas to be mass analyzed by discharge, which is arranged in an insulated state in a main body forming the ion source. Since the holding means to be provided, the energizing means for supplying power to the discharge needle from the outside of the ion source, and the driving means for moving the holding means forward and backward in the length direction of the discharge needle, the discharge needle The position adjustment can be set while discharging.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of an ion source of an atmospheric pressure ionization mass spectrometer according to the present invention.

FIG. 2 is a front sectional view showing a second embodiment of the ion source of the atmospheric pressure ionization mass spectrometer according to the present invention.

FIG. 3 is a configuration diagram showing a discharge needle positioning device of an ion source of an atmospheric pressure ionization mass spectrometer according to the present invention.

FIG. 4 is a front sectional view showing an ion source of a conventional atmospheric pressure ionization mass spectrometer.

[Explanation of Codes] 1 ion source block 2 discharge needle 3 insulator 4,5 groove 6 housing 7,8 counter electrode 9 pinhole 10 discharge needle 11 insulator 12 bellows 13 main body 14 micrometer 15 heater 16 thermocouple 17 gas Supply port 18 Gas exhaust port 19 Insulator 20 Cable 21 O-ring 22 Straight-line introduction machine 22a Mounting plate 23 O-ring 24 Insulator 25 Motor 26 Motor fixing stand 27 Quadrupole mass spectrometer 28 Ion detection part 29 Arithmetic processing part 30 Motor Drive circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadao Matsuoka 3-3 Fujibashi, Ome-shi, Tokyo 2 Hitachi Hitachi Electronics Co., Ltd. Central Research Laboratory

Claims (3)

[Claims] 1. An ion source of an atmospheric pressure ionization mass spectrometer equipped with a discharge needle for ionizing a gas to be subjected to mass analysis by electric discharge, wherein an insulation is provided in a main body forming a casing of the ion source. Holding means arranged in a state, an energizing means for supplying power to the discharge needle from outside the ion source, and a driving means for moving the holding means forward and backward in the length direction of the discharge needle. Ion source for atmospheric pressure ionization mass spectrometer. 2. The ion source for an atmospheric pressure ionization mass spectrometer according to claim 1, wherein the holding means holds the discharge needle via an insulator. 3. A discharge needle positioning device for an ion source according to claim 1, wherein the discharge needle is moved based on the detection value of the ion detector, and the drive means is driven. A discharge needle positioning device comprising a motor as a source and a drive circuit for driving the motor based on the arithmetic means.