JP2794098B2 - Inductively coupled plasma mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductively coupled plasma mass spectrometer employing a heating vaporization method capable of performing highly sensitive quantitative analysis.

[0002]

2. Description of the Related Art Even if a small amount of metal impurities is mixed into a thin film formed on a substrate of an LSI, the electrical characteristics of the LSI are greatly affected. It is essential to analyze trace metal impurities with high sensitivity. In performing this analysis, an inductively coupled plasma mass spectrometer employing a heating vaporization introduction method is used.

[0003] This type of inductively coupled plasma mass spectrometer will be described with reference to the drawings. FIG. 3 shows a schematic configuration of the inductively coupled plasma mass spectrometer.

As shown in FIG. 3, the inductively coupled plasma mass spectrometer is roughly divided into a heating and vaporizing device 10, a torch 20, and a mass spectrometer 30. The heating vaporizer 10 generates a vaporized sample by heating the liquid sample to be analyzed,
The vaporized sample is sent to the torch 20 by an argon gas as a carrier gas. The torch 20 generates a plasma discharge by a high-frequency electrode, and ionizes a vaporized sample by the energy of the plasma. The mass spectrometer 30 has a quadrupole mass filter 31, a multiplier 32, a vacuum pump 33, a computer 34, etc., and obtains a mass spectrum of an ionized vaporized sample drawn by a pressure difference between the torch 20 and the mass spectrometer 30. Configuration.

FIG. 4 shows the inside of an electric furnace provided in the heating and vaporizing apparatus. In the figure, reference numeral 11 denotes an electric furnace, in which a graphite tube 12 is provided.
The graphite tube 12 is heated by a heater block. The outer wall of the graphite tube 12 is provided with a hole 121 having a diameter such that the micropivet α can be inserted therein, and the sample solution injected by the micropivet α is provided inside the graphite tube 12. A receiving board 122 is provided. An argon gas as a carrier gas is introduced into the graphite tube 12, and a sample vaporized by the argon gas is sent to the torch 20 side.

That is, when the micropivet α is inserted into the hole 121 and the sample solution (20 microliters) is injected into the graphite tube 12, the sample solution is received on the board 122. After the injection, a carbon rod (not shown) is inserted into the hole 12 to close the hole 12. When the heater block is energized in this state, the sample solution is heated through the graphite tube 12 and the board 122. When the sample solution is vaporized, the vaporized sample (hereinafter, referred to as a vaporized sample) is sequentially sent to the torch 20 and the mass spectrometer 30 on the flow of argon gas, and finally the sample solution is Trace metal impurities contained therein are analyzed.

[0007]

However, in the case of the above conventional example, if argon gas is used as the carrier gas, there is a disadvantage that the detection limit of iron (Fe) is not good. When the cause was investigated, argon (Ar: mass number 40) as a carrier gas and oxygen (O: mass number 16) of water in the sample solution were combined to form ArO (mass number 56).
Was generated, and the generated ArO became a background in performing the quantitative analysis, and it was found that the detection limit of iron (Fe: mass number 56) was lowered.

Therefore, the heating profile in the graphite tube 12 is devised as follows. That is,
Perform low-temperature (about 150 ° C) heating for a long time (about 90 seconds) to sufficiently vaporize the water in the sample solution, and then heat it to the high temperature necessary to vaporize components other than water in the sample solution. For a predetermined time. Despite these efforts, water components remain in the graphite tube 12, the torch 20, etc., and the detection limit for iron (Fe) is about 500 picograms / gram.
At present, it cannot be increased to more than 1 liter, and the present situation is that the inherent performance of the inductively coupled plasma mass spectrometer cannot be sufficiently exhibited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and an object of the present invention is to provide an inductively coupled plasma mass spectrometer improved so that water components in a sample solution do not reach a torch. To provide.

[0010]

An inductively coupled plasma mass spectrometer according to the present invention comprises a torch for ionizing a vaporized sample fed by an argon gas as a carrier gas by plasma, and a mass spectrum of the ionized vaporized sample. In an inductively coupled plasma mass spectrometer equipped with a mass spectrometer to be sought, a tube connected between the heated vaporizer and the torch, and for guiding the vaporized sample ,
Circulating cooling water to cool the electric furnace inside the heating and vaporizing device
It is characterized by utilizing water cooling from outside
ing.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the inductively coupled plasma mass spectrometer of the present invention will be described below with reference to the drawings. Since the outline of the inductively coupled plasma mass spectrometer has already been described with reference to FIGS. 3 and 4, this description will be omitted, and the description will focus on parts related to the present invention.

FIG. 1 is a schematic view showing a portion of a heating vaporizer and a torch. As shown, a tube 40 is connected between the heating vaporizer 10 and the torch 20 for guiding the vaporized sample from the heating vaporizer 10 to the torch 20 together with argon gas as a carrier gas. Here tube 40
Is made of Teflon and has an outer diameter of 6.35 mm.

A cooling agent 50 for cooling the tube 40 from outside with cooling water is provided at an intermediate position of the tube 40. FIG. 2 is an external view of the cooling pipe. As shown in the figure, the cooling agent 50 is a double-walled glass tube or the like, and has a hole at the center where a tube 40 can be inserted.Outside ends of both ends, a cooling water inlet 51 and an outlet 52 are provided. Each is provided.
The inlet 51 is directed downward and a water supply tube 53 is connected, while the outlet 52 is directed upward and a water discharge tube 54 is connected. The reason why the inlet 51 is directed downward and the outlet 52 is directed upward is to increase the cooling efficiency.

The heating and vaporizing apparatus 10 includes an electric furnace (see FIG. 4).
A device for water-cooling is provided, and the forced cooling water used for this is pulled out and flows to the cooling pipe 50. That is, the forced cooling water of the heating vaporizer 10 is returned to the heating vaporizer 10 again through the water supply tube 53, the cooling officer 50, and the water discharge tube 54. The torch 20
The cooling pipe 50 and the like are covered by the torch box 7 as shown.

Therefore, in the case of using the above-described inductively coupled plasma mass spectrometer, the vaporized sample is cooled by the cooling pipe 50 in the process of sending the vaporized sample from the heating vaporizer 10 to the torch 20 by the argon gas, and the vaporized sample is cooled. The water vapor contained condenses and adheres to the inner wall of the tube 40. As a result, the water component contained in the vaporized sample is
Is less likely to be reached. This means that ArO generated by the combination of argon and water also rarely reaches the torch 30. According to this example, the detection limit of iron is 100 picograms, which is 5 times higher than before.
/ Liter improved.

Further, if the analysis is continued for a long time, the amount of water adhering to the tube 40 increases. Therefore, the time is determined, the apparatus is stopped, the tube 40 is removed, and the inside of the tube 40 is removed with acetone gas or the like. Try to clean. In this way, another problem does not occur due to the water attached to the tube 40.

The inductively coupled plasma mass spectrometer according to the present invention is not limited to the above embodiment. For example, a cooling pipe having a spiral shape with respect to the tube may be used.

[0018]

As described above, the inductively coupled plasma mass spectrometer according to the present invention uses argon gas as a carrier gas.
The vaporized sample sent is ionized by plasma.
Torch and mass spectrum of ionized vaporized sample
Coupled plasma mass with mass spectrometer to determine
Connection between heated vaporizer and torch in analyzer
The tube for conducting the vaporized sample is heated and vaporized.
Utilizing circulating cooling water to cool the electric furnace inside the device
It is characterized by water cooling from outside.
Therefore, the water vapor contained in the vaporized sample condenses and adheres to the inner wall of the tube, so that the water component in the sample solution rarely reaches the torch. Therefore, ArO, which has been a background in performing the quantitative analysis, rarely reaches the torch, and there is an advantage that the detection limit of iron (Fe) is increased as compared with the related art. Therefore,
It is possible to sufficiently exhibit the inherent performance of the inductively coupled plasma mass spectrometer. In addition, because the tubes are water-cooled using circulating cooling water for cooling the electric furnace in the heating and vaporizing device, there is no need for special equipment for cooling, which is an advantage in terms of cost. There is.

[Brief description of the drawings]

FIG. 1 is a view for explaining one embodiment of the present invention, and is a schematic view showing a portion of a heating vaporizer and a torch.

FIG. 2 is an external view of a cooling pipe.

FIG. 3 is a diagram for explaining a conventional example, and is a configuration diagram of an inductively coupled plasma mass spectrometer.

FIG. 4 is a view showing the inside of an electric furnace provided in the heating and vaporizing apparatus.

[Explanation of symbols]

 10 Heat vaporizer 20 Torch 40 Tube 50 Cooling tube

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 49/04 H01J 49/10 G01N 27/62

Claims (1)

(57) [Claims] 1. A heating vaporizer for heating a sample solution to generate a vaporized sample, a torch for plasma-ionizing a vaporized sample fed by an argon gas as a carrier gas, and a mass spectrum of the ionized vaporized sample. In the inductively coupled plasma mass spectrometer provided with the mass spectrometer to be sought, a tube connected between the heating vaporizer and the torch and for guiding the vaporized sample is provided with a heating gas
Utilizes circulating cooling water to cool the electric furnace inside the
An inductively coupled plasma mass spectrometer characterized by being cooled by water from outside .