JPS5966043A - Ion microanalyzer - Google Patents

Abstract

PURPOSE:To remove a neutral corpuscular beam mixed in a primary ion beam, by disposing a propagation path for the ion beam having passed an exhaust slit at the ion source side at a position outside the ion beam passing region of another exhaust slit for deflection. CONSTITUTION:An ion microanalyzer is made up of the following processes that a deflecting electrode 16 is installed between exhaust slit 5 and a lens 6, and the regions of the slit 5 and an exhaust slit 7 are made into a high vacuum, while an ion source 3 is disposed so as to cause a propagation path for an ion beam having passed the slit 5 to be situated outside the ion beam passing region and then a secondary ion out of a sample 9 is fed to a mass spectrometer 10. Therefore, a neutral corpuscular beam 17 to be mixed in the ion beam goes straight without receiving deflection by the deflecting electrode 16 and is intercepted by the slit 7, eliminating the influence of the neutral corpuscular beam, thus highly accurate analysis can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion microanalyzer, and in particular, removes a neutral particle beam mixed in a -order ion beam,
The present invention relates to an ion microanalyzer suitable for micro-subplate and depth direction analysis.

An ion microanalyzer is used to irradiate a sample with an ion beam and perform mass spectrometry on the secondary ions emitted from the sample. FIG. 1 shows a configuration diagram of -order ion irradiation light of a conventional ion microanalyzer. In the figure, the gas in the gas reservoir 1 is supplied to the ion source 3 through the valve 2. In the ion source 3, plasma discharge is generated by inflow gasification and by setting the IIC commercial pressure to 1J degrees. The ions t generated by the ion source 3 are emitted as an ion beam from the generation hole 4, and are emitted as an ion beam through the differential pumping slit 5, lens 6,
The sample 9 is irradiated via the differential exhaust slit 7 and the lens 8. - Secondary ions are released from the sample 9 by irradiation with secondary ions. This secondary ion is supplied to the mass spectrometer 10 and subjected to mass analysis. Excess gas that flows into the ion source 3 and is not subjected to ionization is exhausted by the vacuum exhaust device 11. Furthermore, the spaces between the ion source 3, the differential evacuation slits 5 and 8 are evacuated by evacuation devices 12 and 13, respectively, and a pressure gradient is created so that the area where the sample 9 is stored is in a high vacuum state. is attached.

When the microscopic part M1 of the sample 9A shown in FIG. 2(A) is analyzed using the conventional ion microanalyzer with such a configuration, the microscopic part M1 is detected as shown in FIG. 2(B). In addition, a spectrum of the minute portion M2 appears. Also, the layer ml and the layer m in the depth direction shown in (A) of Fig. 53.
When analyzing the depth direction of sample 9B consisting of
As shown in (13) in the figure, #fW of layer m1 is
It was not possible to analyze only layer m1 in the depth direction due to the influence of the concentration of . As shown in Figure 4, the cause of these problems is that the neutral particle beam is mixed into the -order ion beam, causing sample 9
It has been experimentally confirmed that A, 913 is irradiated.

As described above, in the conventional microanalyzer, it is not possible to accurately perform minute part analysis and depth direction analysis due to the neutral particle beam mixed into the primary ion beam.

Therefore, an ion microanalyzer as shown in FIG. 5 was proposed in order to solve the above-mentioned conventional drawbacks. This ion and microanalyte has four pairs of deflection electrodes 14A, 14B between the ion source 3 and the differential pumping slit 5.
14C, 141) and an aperture 1 between them.
5. In the case of the analyzer shown in FIG. 5, only the charged beam of the ion beam generated from the ion source 3 is deflected, and the neutral beam that is not deflected is focused in the static field. 11115. (7But with this analyzer ν′, sample 9
The irradiation amount of the neutral particle beam irradiated was reduced to only about Fil/10. In addition, in the case of this analyzer, the ion propagation path is longer than t, so the ion amount is 1/3 to 1/10.
The disadvantage was that it decreased. Note that the negative ion current amount has an adverse effect on the analysis time and analysis time.

Therefore, even with the Anamic' shown in FIG. 5, it was not possible to perform high precision analysis.

The present invention has been made in view of the above-mentioned conventional problems,
The purpose is to provide an ion microanalyzer with high analysis accuracy by removing neutral particle beams mixed in the primary ion beam without reducing the secondary ion current.

In order to achieve the above object, the present invention has a plurality of exhaust slits in the ion beam propagation path, and the ion beam generated from the raw hole of the ion source is passed through the source side exhaust slit. [Propagating, this ion beam is
The ion beam, which has been finely focused by a silicon lens and made into a Ml1 bundle, is irradiated onto a C sample via a ion beam, and an ion microphone [1 'In the analyzer, the ion source side 1
A region between the gas slit and the other adjacent exhaust slit is placed in a high vacuum state, and a deflector is provided between the ion source side slit and the electrostatic lens,
In addition, the ion beam generation hole of the ion beam is arranged at a position where the propagation path of the ion beam passing through the exhaust slit on the ion source side is outside the passing area of other exhaust slits, and The ion beam propagation path after passing through the exhaust slit is deflected by the deflector into the ion beam passage area of another exhaust slit.

That is, the amount of neutral particles present can be calculated by collisions between residual gas molecules and ions, and the number of collisions NΣ is expressed by the following equation.

πσ2: Collision i of molecules and ions [Area 1: Collision distance N
1F P: A empty degree ■, secondary ion current ′■゛: temperature As shown in equation (1) above, the number of collisions NΣ is proportional to the vacuum degree P and the primary ion current l. (-maybe the above (1
) It has been experimentally confirmed that the number of collisions NΣ determined by the equation (2) and the actual measured value almost match each other. This means that in each of the ion microanalyzers, the degree of generation of the neutral particle ion beam varies in the region between the ion source 3 and the differential slit 5. The present invention has been made with attention to the above points.

Hereinafter, a preferred embodiment of the present invention will be explained based on FIG. 1ff1.

In FIG. 6, a block diagram of a preferred embodiment of the present invention is omitted.

The ion microanalyzer in this embodiment is provided with a deflection electrode 16 as a deflector between the differential pumping slit 5 and the lens 6, and the region between the differential pumping slit 5 and the differential pumping slit 7 is 2, place the ion source 3 in a position where the ion beam propagation path after passing through the differential exhaust slit 91.5 is outside the ion beam passage area of the differential exhaust slit 7, and then The ion beam propagation path after passing through the ion beam is deflected by the deflection electrode 16 into the ion beam passage area of the differential exhaust slit 7, and the other configuration is the same as that in FIG. Therefore, the same reference numerals will be used to refer to the same parts, and their explanation will be omitted.

In the ion microanalyzer shown in FIG. 6, the neutral particle beam 17 mixed into the ion beam generated by the ion source 3 is not deflected by the screen electrode 16, and therefore passes through the ion beam through the differential pumping slit 8. It reaches outside the area and is cut off by 3J&. Therefore, the sample 9 is not irradiated with the neutral particle ion beam.

As described above, since the ion microanalyzer in this embodiment deflects the ion beam using one stage of deflection electrodes, the ion trajectory is not lengthened and the primary ion current can be prevented from decreasing. Furthermore, since the sample 9 is not irradiated with the neutral particle ion beam, highly accurate analysis can be performed.

FIG. 7 shows a configuration diagram of another embodiment of the present invention.

In the ion microanalyzer 1 in this embodiment, the casing surrounding the ion beam propagation path is placed vertically on the same axis, and the ion beam generation hole 4 of the ion source 3 is placed on the axis of the ion beam propagation path after deflection. The other configurations are the same as those shown in FIG. 6.

- In the example, in addition to the effects of the above example - (
, since the casing surrounding the propagation path is placed coaxially, −
Even when the next ion irradiation system is arranged perpendicular to the sample, stable 1lllJ determination can be performed and assembly accuracy can be improved.

In addition, the deflection electrode 16 in each of the above embodiments has the following (2).
An electric field E shown in the equation is applied.

Here, V secondary ion acceleration '11 pressure Z: amount of deflection at the electrode l: length of the electrode, ie, electric field E, is proportional to the primary ion acceleration pressure V.

On the other hand, an ion microanalyzer performs analysis in the depth direction by utilizing the sputtering phenomenon that occurs when a sample is irradiated with primary ions. This sputtering speed S is
It is a function of the primary ion acceleration pressure as expressed by the following equation.

5=Ki-v・・・・・・・・・・・・(3) Therefore, the jJ sputtering speed can be selected by changing the primary ion acceleration voltage.Therefore, the deflection electrode voltage VD If V is linked to the primary ion accelerating voltage V and these are combined at one point, it is not necessary to set the voltage Vn of the deflection electrode, and operability can be improved.

For this reason, the acceleration electrode and deflection electrode in this embodiment are constructed as shown in FIG. That is, as shown in FIG.
supply to. This secondary ion accelerating power source 23ij outputs a high voltage and applies it to the accelerating electrode 24 of the ion source 3. Also amplification ×
The output of the beam 22 is supplied to a deflection electrode power supply 27 via an adjustment resistor 25 and an amplifier 26. The output of the deflection electrode power supply 27 is applied to the deflection electrode 16. As a result, the ion beam accelerated by the accelerating electrode 24 is separated into an ion beam 30 and a neutral particle beam 32.

That is, there is a relationship between the deflection electrode pressure Vn, the primary ion acceleration J, i, and the pressure (Q) as shown below.

Vn = 3 ・■ ・・・・・・・・・・・・・
(4) In this way, according to the non-implemented relay, even if deflection electrodes are added, there will be no troubles or troubles due to glare from outside, →l°ψ operation, and the analysis accuracy will be improved. can be achieved.

In each of the above-mentioned embodiments, the electric field of the deflection electrode can be lowered in order to minimize the amount of direction t, jlIrIl and block neutral particles at a distant position.

As described above, according to the present invention, it is possible to remove the neutral particle beam mixed in the primary ion beam without reducing the negative ion current, so that highly accurate analysis can be performed.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional primary ion irradiation system; Figures (A) and (B) are diagrams for explaining depth direction analysis using a conventional ion microanalyzer, and Figure 4 shows the state in which a neutral particle beam is mixed into the primary ion beam in a conventional ion microanalyzer. Figure 5 is a diagram for explaining the configuration of another conventional primary ion irradiation system.
Fig. 6 is a block diagram of a primary ion irradiation system showing one embodiment of the present invention, Fig. 7 is a block diagram of a primary ion irradiation system showing another embodiment of the present invention, and Fig. 8 is an acceleration diagram according to the present invention. It is a figure which shows the structure of the storm air system of an electrode and a deflection electrode. 3... Ion source, 4... Ion beam generation hole, 5.
7... Differential exhaust slit, 6.8... Lens, 9.
・・Sample, 舒/m station f side

Claims (1)

[Claims] 1. The ion beam propagation path has a plurality of exhaust slits, and the ion beam generated from the ion generation hole of the ion source is propagated through the ion front exhaust slit 7, and the ion beam is kept static. By electric lens! 1lI1. In an ion microanalyzer that irradiates a sample with a finely bundled ion beam through another exhaust slit and performs mass spectrometry on secondary ions emitted from the sample, the ion source (Ill exhaust slit and this A region between the exhaust slit and another adjacent exhaust slit is made into a high-A empty state, and a deflector is provided between the ion source (i1!I slit and the electrostatic lens), and the ion source side exhaust slit is The ion beam generation hole on the ion source side is arranged at a position where the ion beam propagation path after passing is outside the ion beam passing area of other exhaust slits, and
An ion microanalyzer characterized in that the ion beam propagation path after passing through fi is deflected by an MiJ deflector into an on-beam passing region of another exhaust slit. 2. Claim '4P, wherein a housing surrounding the ion beam propagation path is arranged coaxially, and the ion beam generation hole of the ion source is located at a position different from ++q++ above the deflected ion beam propagation path by t. The ion microanalyzer described in item 1. 3. The ion microanalyzer according to claim 1 or 2, wherein the deflection voltage η of the deflector changes in conjunction with an acceleration voltage for accelerating primary ions generated from the ion source.