JPH08227689A - Secondary ion mass spectrometric device - Google Patents

Abstract

PURPOSE: To reduce the error of an analysis result by minimizing the fluctuation of field strength or distribution, even when the different positions of a sample or a different sample is analyzed. CONSTITUTION: A potential adjustment board 3 is provided between a sample holder 1 and an extraction lens 4 in such a state as adjacent to the holder 1, and receives the same voltage as the holder 1 from a power source 6. The board 3 is laid in parallel to the lens 4, and has an aperture sufficiently larger than a sample 2 mounted on the holder 1. Thus, the board 3 and the holder 1 can be kept in an equipotential state. When a measurement position on the sample 2 is changed. or a different sample 7 is analyzed, the holder 1 is caused, to slide on the board 3, thereby changing the irradiation position of primary ions 10 on the holder 1. As a result, the measurement position on the sample 2 can be changed, or the different sample 7 can be analyzed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary ion mass spectrometer, and more particularly to a secondary ion mass spectrometer for mass spectrometry using a magnetic field.

[0002]

2. Description of the Related Art Conventionally, in a secondary ion mass spectrometer of this type, as shown in FIG. 3, a sample 2 mounted on a sample holder 1 is irradiated with primary ions 10 and the primary ions 10 are irradiated by the irradiation. The secondary ions 11 emitted from the surface of the sample 2 are converged by the extraction lens 4 and introduced into the mass spectrometer 5.

Here, in order to accelerate the secondary ions 11 to a constant energy, a high voltage is usually applied to the sample holder 1 from the power source 6, but a positive voltage is detected again when positive ions are detected. A negative voltage is applied when detecting anions.

Since the electrode outside the extraction lens 4 has almost zero potential, a high electric field is formed between the sample holder 1 and the extraction lens 4, and the secondary ions 11 are introduced into the mass analyzer 5 while being accelerated. It Further, the primary ions 10 are irradiated onto the surface of the sample 2 while being decelerated or accelerated in a high electric field between the sample 2 and the extraction lens 4.

On the other hand, when a sample 7 different from the sample 2 is mounted on the sample holder 1, the sample holder 1 is moved by a driving mechanism (not shown) to which the sample holder 1 is fixed so that the primary ions 10 are removed. The sample 7 is analyzed by irradiating the sample 7. The above technique is described in detail in JP-A-60-198440.

[0006]

In the above-mentioned conventional secondary ion mass spectrometer, when performing analysis of different parts of a sample or analysis of different samples, the sample holder is moved by the drive mechanism to move the primary ions of the sample to the sample. Irradiation is made on different parts and different samples.

Various problems occur when moving the sample holder. For example, when the upper surface of the sample holder, that is, the surface having an opening for irradiating the sample with primary ions is tilted with respect to the drive axis of the drive mechanism, the distance between the extraction lens and the sample is increased by the movement of the sample holder. fluctuate. That is, the distance between different parts of the sample and the extraction lens or the distance between different samples and the extraction lens may become longer or shorter than the distance between the sample that was first analyzed and the extraction lens.

As a result, the focusing efficiency of the secondary ions fluctuates, or the strength and distribution of the electric field between the sample and the extraction lens fluctuate. For example, when analyzing the boron concentration of a sample obtained by doping silicon single crystal with boron, as shown in FIG. 4, the concentration changes depending on the moving distance of the sample holder, and an error of about 10% occurs depending on the moving distance. Will end up.

Therefore, an object of the present invention is to solve the above problems, to minimize variations in electric field strength and distribution and reduce errors in analysis results even when different parts of a sample or different samples are analyzed. Another object is to provide a secondary ion mass spectrometer capable of

[0010]

In a secondary ion mass spectrometer according to the present invention, secondary ions generated from the surface of a sample when the sample is irradiated with primary ions are converged by an extraction lens and mass analyzed by a magnetic field. A secondary ion mass spectrometer, wherein a potential adjusting plate disposed parallel to the extraction lens, and a potential adjusting plate disposed in proximity to the potential adjusting plate and holding the sample, with respect to the potential adjusting plate. And a means for applying equipotential voltages to the potential adjusting plate and the sample holder, respectively.

Another secondary ion mass spectroscope according to the present invention is a secondary ion mass spectrometric apparatus for concentrating secondary ions generated from the surface of the sample when the sample is irradiated with the primary ions by a drawing lens and performing mass analysis with a magnetic field. An apparatus, which is an electric potential adjusting plate arranged parallel to the extraction lens, a sample holder which is slidable with respect to the electric potential adjusting plate and holds the sample, the electric potential adjusting plate and the sample The holder and means for applying equipotential voltage respectively.

[0012]

[Function] In a secondary ion mass spectrometer in which secondary ions generated from the surface of a sample when the sample is irradiated with primary ions are converged by an extraction lens and mass-analyzed by a magnetic field, a potential adjusting plate is parallel to the extraction lens. A sample holder that holds the sample and can move in parallel to the potential adjusting plate is placed close to the potential adjusting plate, and equipotential voltages are applied to these potential adjusting plate and sample holder, respectively. To do.

As a result, the distance between the sample and the extraction lens is always kept constant even when different parts of the sample or different samples are analyzed, so that variations in the electric field strength and distribution are minimized, and errors in the analysis result are suppressed. Can be made smaller.

Further, even when the sample to be analyzed is exchanged, the distance between the sample and the extraction lens can be kept constant at all times, and therefore the electric field distribution and the trajectories of primary ions become constant, so that highly accurate analysis is possible. Becomes

[0015]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, the potential adjusting plate 3 is disposed between the sample holder 1 and the extraction lens 4 so as to be adjacent (close to) the sample holder 1, and the same voltage as that of the sample holder 1 is applied from the power source (HV) 6. Has been done. In addition, the potential adjusting plate 3
Is installed parallel to the extraction lens 4 and has an opening that is sufficiently larger than the sample 2 mounted on the sample holder 1. Therefore, the potential adjusting plate 3 is kept at the same potential as the sample holder 1.

When changing the measurement location on the sample 2 or when analyzing a different sample 7, the sample holder 1 is slid with respect to the potential adjusting plate 3 to remove the primary ions 10 on the sample holder 1. Change the irradiation position. This makes it possible to change the measurement location on the sample 2 and analyze a different sample 7.

There are various methods for holding the sample 2, but by pressing the sample 2 from the upper surface of the sample holder 1, that is, the rear surface of the surface having the opening hole for irradiating the sample 2 with the primary ions 10, The sample 2 can be held without disturbing the sliding of the sample holder 1 with respect to the potential adjusting plate 3.

Also, in the method of holding the sample 2 by adhering it to the sample holder 1 with silver paste or the like,
By providing a concave portion for holding the sample 2 and holding the sample 2 so that the surface of the sample 2 is retracted by a certain distance from the surface of the sample holder 1, sliding of the sample holder 1 with respect to the potential adjusting plate 3 is not hindered. .

In any holding method, if the distance between the samples 2 and 7 and the extraction lens 4 is kept constant when the sample holder 1 is moved, the focusing efficiency of the secondary ions 11 may fluctuate, or The intensity and distribution of the electric field between the samples 2 and 7 and the extraction lens 4 do not change.

If the distance between the sample to be analyzed and the extraction lens 4 is kept constant even when the sample to be analyzed is exchanged, the focusing efficiency of the secondary ions 11 may fluctuate, or the samples 2 and 7 may be extracted. The strength and distribution of the electric field with the lens 4 do not change. In order to keep the distance between the samples 2 and 7 and the extraction lens 4 constant, the drive shaft of the drive mechanism (not shown) for driving the sample holder 1 and the potential adjusting plate 3 should be parallel. , Sample holder 1 on it
May be slid with respect to the potential adjusting plate 3.

FIG. 2 is a diagram showing an example of analysis of a uniform concentration sample according to one embodiment of the present invention. In the figure, the result of analyzing the boron concentration of a sample in which a silicon single crystal is doped with boron is shown.

In this case, since the distance between the samples 2 and 7 and the extraction lens 4 is kept constant when the sample holder 1 is moved, the focusing efficiency of the secondary ions 11 varies or the sample 2 , 7 and the extraction lens 4 do not fluctuate in the strength or distribution of the electric field, so the measurement error is 2% or less. Therefore, even when different parts of the sample 2 or different samples 7 are analyzed, the samples 2, 7
The reproducible analysis for

As described above, in the secondary ion mass spectrometer in which the secondary ions 11 generated from the surface of the sample 2 when the sample 2 is irradiated with the primary ions 10 are converged by the extraction lens 4 and mass-analyzed by the magnetic field, the potential adjustment is performed. The plate 3 is arranged parallel to the extraction lens 4, and the sample holder 1 that holds the sample 2 and is movable in parallel to the potential adjusting plate 3 is arranged close to the potential adjusting plate 3. By applying equipotential voltages to the potential adjusting plate 3 and the sample holder 1, respectively, the distance between the samples 2 and 7 and the extraction lens 4 is always constant even when different parts of the sample 2 or different samples 7 are analyzed. Since this is maintained, fluctuations in the electric field strength and distribution can be minimized, and errors in analysis results can be reduced.

Further, even when the sample to be analyzed is exchanged, the distance between the sample and the extraction lens 4 can be kept constant at all times, so that the electric field distribution and the trajectory of the primary ions 10 become constant, so that highly accurate analysis is possible. Is possible.

[0026]

As described above, according to the present invention, the secondary ion mass spectrometer for secondary ions generated from the sample surface when the sample is irradiated with the primary ions is converged by the extraction lens and mass-analyzed by the magnetic field. , The potential adjusting plate is arranged parallel to the extraction lens, and the sample holder that holds the sample and is movable parallel to the potential adjusting plate is arranged close to the potential adjusting plate. By applying equipotential voltages to the adjustment plate and sample holder respectively, fluctuations in electric field strength and distribution can be minimized and errors in analysis results can be reduced even when different parts of the sample or different samples are analyzed. The effect is that you can do it.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of analysis of a uniform concentration sample according to an example of the present invention.

FIG. 3 is a configuration diagram showing a configuration of a conventional example.

FIG. 4 is a diagram showing an analysis example of a uniform concentration sample according to a conventional example.

[Explanation of symbols]

 1 Sample Holder 2, 7 Sample 3 Potential Adjustment Plate 4 Extraction Lens 5 Mass Spectrometer 6 Power Supply 10 Primary Ion 11 Secondary Ion

Claims (4)

[Claims] 1. A secondary ion mass spectrometer for concentrating secondary ions generated from the surface of a sample when a sample is irradiated with primary ions by an extraction lens and performing mass analysis with a magnetic field, wherein A potential adjusting plate arranged in parallel, a sample holder arranged in proximity to the potential adjusting plate and holding the sample and movable in parallel to the potential adjusting plate, and the potential adjusting plate A secondary ion mass spectrometer, comprising: means for applying an equipotential voltage to the sample holder, respectively. 2. The secondary ion mass spectrometer according to claim 1, wherein the sample holder is configured to hold the sample below a surface adjacent to the potential adjusting plate. 3. A secondary ion mass spectrometer for concentrating secondary ions generated from the sample surface when a sample is irradiated with primary ions by a drawing lens and performing mass analysis by a magnetic field, wherein A potential adjusting plate arranged in parallel, a sample holder that is slidable with respect to the potential adjusting plate and holds the sample, and an equipotential voltage are applied to the potential adjusting plate and the sample holder, respectively. And a secondary ion mass spectrometer. 4. The secondary ion mass spectrometer according to claim 3, wherein the sample holder is configured to hold the sample below a surface that slides with respect to the potential adjusting plate. .