JPH0438440A - Quantity analysis sample and ion implantation and secondary ion mass spectrometer with ion implantation function - Google Patents

Abstract

PURPOSE:To omit a standard sample besides an analysis objective sample by providing a known amount of the same element as the analysis objective element in the analysis objective sample as an internal standard sample. CONSTITUTION:In a secondary ion mass spectrometer, an ion source 2 is provided to inject a known amount of internal standard element same as the element to be analyzed into a quantity analysis objective sample 11 as an internal standard sample. Symbol 3b shows the aperture for the ion source 2 for injecting an internal standard element and 4b shows the condenser lens for the ion source 2 for injecting an internal standard element. This system shares the system of mass separator 5 to separate mass of ion beam 18 discharged from the primary ion source 1 for analysis purpose and a system of mass separator to separate mass of ion beam 19 discharged out of the ion source 2 for internal standard element injection into the quantity analysis objective sample 11 for known amount of internal standard sample.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a quantitative analysis sample used for quantitative analysis of general solid materials, an ion implantation method for implanting ions into the quantitative analysis target sample itself, and an ion implantation function. This invention relates to a secondary ion mass spectrometer.

[Conventional technology]

Ion mass spectrometry (SIMS) is a relative value analysis,
Conventionally, SIMS requires, in addition to the sample to be analyzed, a standard sample having the same matrix as the sample to be analyzed.

The prior art related to standard samples is 1, for example, Japanese Patent Application Laid-open No. 6
It is described in the publication No. 1-71343, and the standard sample shown in the publication is an ion microanalyzer (IM
For A) analysis depth calibration, a standard (tracer) element is ion-implanted to a reference depth.

To briefly explain the principle of IMA, IMA irradiates the surface of a sample with probe ions, expels the surface atoms in the form of ions (secondary ions) (sputtering), and converts the sputtered secondary ions into secondary ions. The next step is to perform elemental analysis of the ion irradiated area by detecting it with an ion detection system and performing mass spectrometry.

Then, by digging in the depth direction while sputtering the sample surface with the probe ion beam as described above, elemental analysis in the depth direction can be performed moment by moment. can be analyzed.

In other words, there is a proportional relationship between sputtering time and analysis depth, and therefore it can be seen that sputtering time corresponds to the concentration distribution in the direction of analysis depth.However, until now, the absolute value of analysis depth itself corresponding to sputtering time has not been known. Analysis depth (absolute value)
Since there was a problem that it was not possible to obtain the concentration distribution for IMA the implanted ions
It is used as a scale for the absolute value of analysis depth.

[Problem to be solved by the invention]

However, in the case of conventional SIMS,
Quantitative analysis of solid materials, including the IMA described in Publication No. 71343, requires a standard sample in addition to the sample to be analyzed, and the secondary ion strength is measured for both the standard sample and the sample to be analyzed. However, it is undeniable that it takes a long time to prepare a standard sample that has the same matrix as the sample to be analyzed, and it is expensive.

The purpose of the present invention is to perform SI, which is a relative value analysis of general solid materials.
When performing MS, there is no need for a standard sample other than one sample to be analyzed as in the past, and therefore there is no need to take a long time to prepare a standard sample that has the same matrix as the sample to be analyzed, as in the past. Ion implantation method and secondary ion mass spectrometer with ion implantation function to specifically obtain quantitative analysis samples, as well as quantitative analysis target samples, which can simultaneously solve the high cost problem associated with standard sample preparation. Our goal is to provide the following.

[Means to solve the problem]

In order to achieve the above object, the quantitative analysis sample according to the present invention is a quantitative analysis sample that is subjected to ion quantitative analysis using an ion microanalyzer.
The internal standard sample is characterized by the presence of a known amount of the same element as the element to be analyzed.

Furthermore, in order to specifically obtain the quantitative analysis sample, the ion implantation method according to the present invention includes ion implantation of a known amount of the same element as the element to be analyzed as an internal standard sample into the quantitative analysis target sample itself. It is characterized by:

Furthermore, the secondary ion mass spectrometer with ion implantation function according to the present invention includes a primary ion source for analysis that irradiates probe ions onto a sample surface, a primary ion mass separator, an ion beam irradiation system, and a secondary ion source. In a secondary ion mass spectrometer equipped with a mass spectrometry system, an ion source for internal standard element injection is added to the sample to be quantitatively analyzed, which injects a known amount of the same element as the element to be analyzed as an internal standard sample. It is characterized by the fact that

[Effect]

According to the ion implantation method and secondary ion mass spectrometer with ion implantation function for specifically obtaining a quantitative analysis sample and a quantitative analysis target sample having the above configuration, it is possible to perform relative value analysis of general solid materials. When implementing a certain SIMS, there is no need for a standard sample in addition to the sample to be analyzed, as in the past, and there is therefore no need to take a long time to prepare a standard sample that has the same matrix as the sample to be analyzed, as in the past. Moreover, the problem of high cost associated with standard sample preparation can also be solved at the same time.

〔Example〕

Hereinafter, the present invention will be explained based on one embodiment of the drawings. FIG. 1 is a partial vertical sectional view showing the overall configuration of a secondary ion mass spectrometer with ion implantation function according to the present invention, and FIG. Figure 1 is an enlarged view of the sputter ion source for internal standard element implantation indicated by reference numeral 2, Figure 3 is a diagram showing the method for calculating quantitative values, and Figure 4 is a diagram showing the method for calculating quantitative values.
The figure shows an example of measuring oxygen in Si in the depth direction.

In FIG. 1 showing the overall configuration of a secondary ion mass spectrometer, 1 is a primary ion source for analysis that irradiates the surface of a sample 11 for quantitative analysis with probe ions, 3a is the 7th perch of the primary ion source for analysis 1, and 4a Similarly, it is a condenser lens of the primary ion source 1 for analysis.

Reference numeral 5 indicates a mass separator for mass-separating the ion beam, and 6 indicates an aperture for mass separation.

7 is a condenser lens located after the mass separation aperture 6, 8 is an objective lens aperture, 9 is an objective lens, 10
is a deflection electrode.

Reference numeral 11 indicates the sample to be quantitatively analyzed as described above.

12 is a secondary ion extraction electrode, 13 is a sector electric field, 14
is a sector magnetic field, and 15 is a secondary ion detector.

Reference numeral 16 indicates a later-stage acceleration power source, which will be described later.

17 is a Faraday cup for measuring ion current.

Therefore, in addition to the above-described configuration, the secondary ion mass spectrometer according to the present invention newly includes the same element as the element to be analyzed as an internal standard sample in the quantitative analysis target sample 11 itself. The gist is that an ion source 2 for implanting an internal standard element is provided for implanting large amounts of ions.

In FIG. 1, reference numeral 3b indicates an aperture of the ion source 2 for implanting internal standard elements, and reference numeral 4b indicates a condenser lens of the ion source 2 for implanting internal standard elements.

In this example, a mass separator system shown by reference numeral 5 in FIG. When ions are implanted into the quantitative analysis target sample 11 itself as a known amount internal standard sample, the system is shared with a mass separator system for mass-separating the ion beam 19 emitted from the ion source 2 for internal standard element implantation, and By sharing the condenser lens 7 system, which is located after the mass separator 5 and through which both the ion beams 18 and 19 pass, and the objective lens 9 system, the overall structure of the apparatus becomes complicated. Efforts have been made to prevent this and to minimize the increase in cost of this type of apparatus newly equipped with the ion source 2 for implanting the internal standard element mentioned above.

In FIG. 2 showing an enlarged view of the internal standard element implantation ion source indicated by the reference numeral 2 in FIG. The ion source material 22 is attached to the part.

That is, the internal standard element implantation ion source 2 described above is
As shown in FIG.
The metal net 23 holding the intermediate electrode 24 and the anode 2
5, an anode button 26, an accelerating electrode 27, a stabilizing resistor 28, plasma excitation discharges @ 29, and an accelerating power source 3
0.

Note that various means for holding the ion source material 22 can be considered depending on the shape of the ion source material 22, but if the ion source material 22 has a block shape, for example, , hollow cathode 20
By attaching the desired type of ion source material 22 to the hollow cathode 20, an ion beam 19 of the desired element can be formed, and sputtered particles The ionization of is efficiently performed in the plasma 32.

In FIG. 2, the operating principle of the internal standard element implantation ion source 2 is as follows.

That is, first, the entire ion source 2 is evacuated to a high vacuum.

Next, the intermediate electrode 24 of the hollow cathode 2o and the anode 2
Inert gas (Ar, Ne,
Nz, etc.) is introduced to a pressure of 1 to 10-3 Torr, and a discharge pressure is applied from the plasma excitation discharge source 29 to form a gap between the intermediate electrode 24 and the anode 25 of the hollow cathode 20. A discharge plasma 31 is generated in the space. Under this situation, the ion source material 2
2 is sputtered through the metal mesh 23 toward the space of the plasma 31. Further, the neutral particles sputtered into the plasma 31 are ionized by the already generated plasma 31, and are extracted as a high-energy beam by the accelerating electrode 27 through the pore of the anode button 26 attached to the center of the anode 25. . Note that at this time, the acceleration voltage is applied to the anode 25 and the acceleration electrode 27 by the acceleration power source 30.
is applied between.

Next, in FIG. 1, a primary ion beam for analysis 18. The internal standard element implantation ion beam 19 is separated by mass number by a mass separator 5,
The output is divided into specific ions and sent to a mass separation aperture 6, a condenser lens 7, an objective lens diaphragm 8. The objective lens 9° is sequentially introduced into the deflection electrode 10, and the same location on the sample 11 to be quantitatively analyzed is irradiated.

That is, the primary ion beam 18 for analysis or the ion beam 19 for internal standard element implantation, which has been condensed by the condenser lens 7 and the objective lens 9, is deflected by the deflection electrode 10 to a predetermined position on the sample 11 to be quantitatively analyzed. The area is irradiated.

On the other hand, the secondary ion extraction electrode 12 to the secondary ion detector 1
The operating principle of the secondary ion mass spectrometry system configured by No. 5 is as follows.

That is, secondary ions are extracted by the secondary ion extracting electrode 12 and guided to the sector electric field 13 to perform energy separation of the secondary ions, and only ions having a specific energy are subjected to sector magnetic separation. The result is detected by the secondary ion detector 15.

In connection with the operation of the internal standard element implantation ion source 2 described above, the internal standard element implantation ion source 2 injects an element for the purpose of analysis into the quantitative analysis target sample 11 itself as an internal standard sample. A known amount of the same element is implanted, and as a result, there is no need for a standard sample in addition to the sample to be analyzed, as in the past, but the amount of ions to be implanted is determined by adjusting the ion beam irradiation system. The Faraday cup 17 is partially inserted into the ion beam path, the amount of ions is measured, and the value is obtained by dividing the product of the irradiation time and the ion current by the irradiation area.

By the way, when high-mass ions are implanted into the quantitative analysis target sample 11, apart from when the energy is high, when the energy is low, the sputtering phenomenon occurs violently, and the injection concentration cannot be accurately suppressed, causing the internal standard sample However, to solve this problem, it is sufficient to change the energy of the implanted ions depending on the implanted ion species. Specifically, as shown in Figure 1, for the sample 11 to be quantitatively analyzed, , a post-acceleration voltage having a polarity opposite to that of the primary ions may be applied from the post-acceleration power supply 16 to form an ion beam having desired energy.

Here, an example of quantitative analysis of oxygen in Si will be shown below with reference to the drawings, although it partially overlaps with the previous explanation.

In addition, in the following analysis example, the target sample 11 for the purpose of quantitative analysis has an oxygen concentration of 1.5×1017 atoms.
/al, and in the measurement, this value was treated as unknown.

First, we will discuss the method of ion-implanting oxygen as an internal standard element to be ion-implanted into the quantitative analysis target sample 11.
Oxygen is introduced into the ion source 2 for internal standard element implantation,
Generate oxygen plasma 31 and extract 01 beam,
7 perch 3b of the ion source 2, condenser lens 4
By focusing the primary ion beam through a mass separator 5 and a mass separation aperture 6, impurity ions contained in the primary ion beam are removed and a high-purity O+ beam is formed.

The O+ beam emitted from the mass separation aperture 6 is then transferred to a condenser lens 7, an objective lens aperture 8. The beam is focused to a desired beam diameter by an objective lens 9, and ions are implanted as an internal standard sample into a portion of a quantitative analysis target sample 11 via a deflection electrode 10.

As mentioned above, the amount of ions to be implanted is determined by adjusting the ion beam irradiation system, inserting the Faraday cup 17 partially into the ion beam path, measuring the amount of ions, and calculating the amount of ions by adjusting the irradiation time and ion current. Calculate the value by dividing the product by the irradiated area.

The ion implantation amount (dose amount) Di for the quantitative analysis target sample 11 is determined by the following formula, where the ion current is Xt (A), the ion beam irradiation area is A (csf), and the irradiation time is t (see). is given by

A @e Here, e is charge (C).

On the other hand, the maximum concentration Ci of the ion-implanted element, wahxC1:
The name of the implanted element (p m & the meaning of the amount of the implanted element) is generally determined from the following formula.

Here, σ is the standard deviation, and this value is uniquely determined once the composition of the quantitative analysis target sample 11, the implanted ion species, and the implantation energy are determined.

In this way, by directly ion-implanting a known amount of the same element as the element targeted for quantitative analysis into a part of the sample 11 to be analyzed, this can be used as an internal standard element.

Next, the secondary ion extraction electrode 12. Sector electric field 13, sector magnetic field 14. Before mass spectrometry of secondary ions is performed by the secondary ion detector 15, the primary ion beam 18 for analysis is passed through the condenser lens 7, the objective lens aperture 8. The beam is focused to a desired diameter by an objective lens 9,
The ion implantation location on the sample 11 to be analyzed is irradiated. In this case, the ion implantation location for the sample 11 is selected by changing the potential of the deflection electrode 10 and deflecting the primary ion beam 18 for analysis.

Secondary ions generated on the sample 11 by the irradiation of the primary ion beam 18 for analysis are guided by the secondary ion extraction electrode 12 to the sector electric field 13 and the sector magnetic field 14, resulting in a mass-to-charge ratio (M/e (M: mass number). , e: charge)] and detected by the secondary ion detector 15.

Note that the measurement is performed by adjusting the mass spectrometer to the ion species to be analyzed and using the depth direction measurement mode of the sample 11.

That is, the primary ion beam 18 for analysis is scanned in a rectangular shape (TV shape) within the ion implantation region of the sample 11, and as a function of the depth direction, ions targeted for analysis and noise (for example, mass number = 5) Measure the intensity simultaneously.

A schematic diagram of the measurement results is shown in FIG.

Then, the quantitative value of oxygen is calculated as follows. The names of symbols in Fig. 3 are as follows:
nm), (, s, □8 and c8: maximum concentration of element i injected as an internal standard sample (ato s/d
) and the concentration of the element to be analyzed contained in the sample (a
toms/d), *wax II Maximum ion current for one element n: Noise intensity (cps), 1
, :c, the elemental concentration (CP
S).

In addition, in Fig. 3, the ion electric current is shown as ■.

The desired concentration CI (atoms/d) of element X in the sample 11 is given by the following formula.

Cx=(Ix/Ii--ax) ・Ct-a
x − (3) where Ix and It are actual measured values, and C1ylla! is the equation (2) before the dose (D)
It can be calculated using

In addition, the quantitative value of sample 11 was evaluated when oxygen was 1.5X 1
Using a silicon wafer containing 0.017 atoms/al and assuming that the quantitative value is not known, it is calculated from the measured value through the above procedure, and the measured value is compared with the known quantitative value.

And the 0+ injection conditions for the internal standard sample are energy:
15KeV, implantation amount (dose amount) D: 10”at
oms/cxl, and from equation (2) above, Co Hmh
x is determined as 2 x 10 ''atoms/d. Also, as the secondary ion irradiation conditions during the quantitative analysis, primary ion species: Cs'' and energy: 15 keV were adopted. An example of the measurement results is shown in FIG. Further, Table 1 shows an example of the results obtained by determining a quantitative value using equation (3) and comparing this with the true value.

Table 1 Relative error: 1% From Table 1, it can be seen that both [quantitative value and true value obtained from equation (3)] agree with each other with a relative error of about 1%.

Thus, according to this example, 1.5X1017 atoms
A trace amount of oxygen of s/aJ can be determined with high accuracy of about 1% as a relative error.

In this example, the results of quantitative analysis of oxygen were illustrated, but B was added to the hollow cathode 20 as the ion source material 22.
,I. Of course, it is possible to load elements such as, and obtain quantitative values for each in the same manner as in the case of oxygen.

〔Effect of the invention〕

The present invention is as described above, and according to the present invention.

When performing SIMS, which is a relative value analysis of general solid materials, there is no need for a standard sample other than the sample to be analyzed, as in the past, and therefore, as in the past, standard samples having the same matrix as the sample to be analyzed are used for long periods of time. Ion implantation methods and ion implantation methods for specifically obtaining quantitative analysis samples, as well as samples to be quantitatively analyzed, which do not require the preparation of standard samples and can also solve the problem of high costs associated with standard sample preparation. A functional secondary ion mass spectrometer can be obtained.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a partial vertical cross-sectional view showing the overall configuration of a secondary ion mass spectrometer with ion implantation function according to the present invention. FIG. 3 is a diagram showing a method for calculating a quantitative value, and FIG. 4 is a diagram showing an example of measuring oxygen in Si in the depth direction. DESCRIPTION OF SYMBOLS 1... Primary ion source for analysis, 2... Ion source for internal standard element implantation, 3a... Aperture for analysis primary ion source, 3b... Aperture for internal standard element implantation ion source, 4
a...Condenser lens for analysis primary ion source, 4b...
・Condenser lens for internal standard element implantation ion source, 5・
・Mass separator, 6...Aperture for mass separation, 7...
・Condenser lens, 8...Objective lens aperture. 9. Objective lens, 10. Deflection electrode, 11. Sample for quantitative analysis, 12. Secondary ion extraction electrode, 13. Sector electric field, 14. Sector magnetic field, 15. Secondary ion detector. 16. Post-acceleration power supply, 17. Faraday cup, 18. Primary ion beam for analysis, 19. Ion beam for internal standard element implantation, 20. Hollow cathode, 21. Ion source material reservoir, 22.・Ion source material,
23... Metal mesh, 24... Intermediate electrode, 25... Anode, 26... Anode button, 27... Accelerating electrode,
28... Stabilizing resistor, 29... Discharge source for plasma excitation, 30... Acceleration power source, 31... Discharge pragma. Figure Figure □ Depth Figure Depth dfnm) ×10

Claims (1)

[Claims] 1. In a quantitative analysis sample to be subjected to ion quantitative analysis using an ion microanalyzer, a known amount of the same element as the element to be analyzed exists in the sample to be analyzed as an internal standard sample. A quantitative analysis sample characterized by: 2. An ion implantation method characterized by implanting ions of a known amount of the same element as the element to be analyzed as an internal standard sample into the sample to be quantitatively analyzed. 3. Quantitative analysis in a secondary ion mass spectrometer that has a primary ion source for analysis that irradiates probe ions onto the sample surface, a primary ion mass separator, an ion beam irradiation system, and a secondary ion mass spectrometry system. A secondary ion mass spectrometer with an ion injection function, characterized in that an ion source for implanting an internal standard element is added to the target sample itself, which implants a known amount of the same element as the element to be analyzed as an internal standard sample. . 4. In claim 3, there is provided a mass separation system for mass-separating the ion beam emitted from the primary ion source for analysis, and a mass separation system for mass-separating the ion beam emitted from the primary ion source for analysis; When injecting,
A condenser lens system and an objective lens, which share the mass separation system for mass-separating the ion beam emitted from the ion source for internal standard element implantation, and are located after the mass separator, and through which both the ion beams pass. A secondary ion mass spectrometer with ion injection function that uses a shared system. 5. In claim 3 or 4, a post-acceleration power supply that applies a post-acceleration voltage having a polarity opposite to that of the primary ions to a quantitative analysis target sample into which ions of the same element as the element to be analyzed are implanted as an internal standard sample in a known amount. Secondary ion mass spectrometer with ion injection function.