JP2001056308A - Sector-type secondary ion mass analyzing method and sample holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform analysis with high resolution in a depthwise direction by inclining the normal direction of a sample from the direction of a secondary ion optical axis to the direction of a primary ion optical axis. SOLUTION: A secondary ion optical axis 5 forms an angle of approximately 30 deg. with a primary ion optical axis 3. Primary ions from an ion source and mass filter 1 for generating primary ions are passed through a primary column 2 to shine a sample 13 held at a sample holder 11 in a sample analyzing chamber 8. The sample holder 11 is provided with such a face as to match the normal direction of the held surface of the sample 13 with the direction of the primary ion optical axis 3. The sample holder 11 on an XY stage 12 irradiates an analysis region, and secondary ions generated by the irradiation with primary ions are passed from a secondary ion deriving electrode 7 to a secondary column 4 and are analyzed at a sector-type mass analyzing part and detector 6 for secondary ions. By this constitution, it is possible to lower the incident energy of the primary ions without lowering a secondary ion deriving voltage and to improve resolution in a depthwise direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grazing incidence type sector secondary ion mass spectrometer widely used for impurity element analysis of various materials and devices.

[0002]

2. Description of the Related Art A sector type secondary ion mass spectrometer (SI)
MS) is widely used for various materials, impurity elements of devices, and the like because it can measure the profile of the detection sensitivity in the height and depth directions.

A sample holder used in a conventional sector-type secondary ion mass spectrometer has a sample mounting surface that is one plane perpendicular to the secondary ion optical axis.

[0004]

When SIMS measurement is performed using a conventional sample holder, if the primary ions and the secondary ions have the same polarity, the primary ions have a direction parallel to the sample surface. Due to the presence of the velocity component, the incident energy of the primary ions has a lower limit proportional to the secondary extraction voltage. In order to reduce the incident energy of the primary ions, the secondary extraction voltage cannot be reduced. Therefore, there is a problem that the transmission efficiency to the mass spectrometer decreases.

[0005]

In order to solve the above problems, a sector type secondary ion mass spectrometer according to the present invention is directed to an analytical method using an oblique incidence type sector type secondary ion mass spectrometer. Is tilted from the direction of the secondary ion optical axis to the direction of the primary ion optical axis.

Also, in the sample holder of the present invention of the incident type sector type secondary ion mass spectrometer, the normal of the first sample mounting surface is in the direction of the secondary ion optical axis from the direction of the secondary ion optical axis. It is characterized by the direction of the primary ion optical axis. Also, the normal line of the first sample mounting surface is perpendicular to the primary ion optical axis.

In the sample holder of the present invention, the first
And a second sample mounting surface perpendicular to the secondary ion optical axis adjacent to the sample mounting surface.

In the present invention, the sample holder is provided with the first
A mechanism for adjusting the position of the sample mounting surface.

In the present invention, the sample holder is provided with the first
A mechanism for adjusting the angle of the sample mounting surface.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific examples.

(Embodiment 1) As Embodiment 1 of the present invention, the present invention will be described with reference to FIG. Here, a sector type secondary ion mass spectrometer in which the secondary ion optical axis and the primary ion optical axis make an angle of 30 degrees with each other is used. The primary ion generated by the primary ion generating ion source and the mass filter unit 1 passes through the primary column 2 and irradiates the sample 13 mounted on the sample holder 11 in the sample analysis chamber 8.
The sample holder 11 has a surface such that the normal direction of the surface on which the sample 13 is mounted substantially coincides with the direction of the primary ion optical axis 3. The sample holder 11 is set on the XY stage 12, and can irradiate an area to be analyzed. Secondary ions generated by irradiating the primary ions are supplied to the secondary column 4 via the secondary ion extraction electrode 7.
Then, it is analyzed by the secondary ion sector mass spectrometer and the detector 6. Further, the mass spectrometer is provided with a preliminary exhaust chamber 10, and carries in the sample via the gate valve 9.

Irradiating O ₂ + ions as primary ions;
Positive ions were analyzed as secondary ions. An experiment was performed with a secondary ion extraction voltage of 1.9 kV, a primary ion extraction voltage of 2.0 kV, and an incident energy of the primary ions of 0.1 kV, and the resolution in the depth direction was improved as compared with a normal analysis method. In the conventional analysis method in which the sample surface is mounted so as to be perpendicular to the secondary ion optical axis, the secondary ion extraction voltage is 3/4 of the primary ion acceleration voltage, that is, 1.
It can only be raised up to 5 kV. Also, the incident energy of the primary ions is 1/3 of the secondary ion extraction voltage,
That is, it can be reduced only to 0.5 kV. In order to reduce the incident energy of the primary ions to 0.1 kV by the conventional method, it is necessary to reduce the primary ion extraction voltage to 0.4 kV and the secondary ion extraction voltage to 0.3 kV, and the transmission efficiency of the secondary ions decreases. , detection limits concentration increases.

According to the analysis method of the present invention, the incident energy of primary ions can be reduced without lowering the extraction voltage of secondary ions, and the resolution in the depth direction can be improved while maintaining the transmission efficiency of secondary ions. did it.

In this embodiment, the sample 1 in the sample holder 11 is
Although the direction of the normal to the mounting surface of 3 is made substantially coincident with the secondary ion optical axis 5, the lower limit of the primary ion extraction voltage is limited if the secondary ion optical axis 5 is set to be closer than the primary ion optical axis 3. Can be alleviated.

(Embodiment 2) As Embodiment 2 of the present invention, a case where another sample holder is used in the apparatus shown in FIG. 1 will be described.

FIG. 2 shows a schematic diagram of the sample holder used in the present analysis. In this embodiment, a sample mounting portion 21 that is not perpendicular to the secondary ion optical axis 17 is provided on a part of the front plate 18. Sample mounting part 21 provided on front plate 18
The concave portion 24 is provided at a location corresponding to. One end of the sample mounted on the sample mounting portion 21 which is not perpendicular to the secondary ion optical axis protruded from the front plate by 300 μm, and was fixed by a leaf spring 22. In this embodiment, the sample mounting unit 21 not perpendicular to the secondary ion optical axis 17 is used.
The normal direction of the sample attached to the sample was set to coincide with the direction of the primary ion optical axis 16.

A sample mounted perpendicularly to the secondary ion optical axis is applied to a back plate 20 via a spring 19.
Pressed and fixed. The sample for adjusting the beam position of the primary ion was mounted on the sample mounting section 23. By using this sample holder, the beam position of the primary ions could be easily known, and the same experimental results as in Example 1 could be obtained.

Another sample holder shown in FIG. 3 is provided with a sample position adjusting mechanism 25 in the sample mounting section 21. Others are the same as the sample holder shown in FIG. By using this sample holder, similar experimental results could be obtained for a small sample of about 2 mm × 1 mm.

In another sample holder shown in FIG. 4, an angle adjusting mechanism 26 is provided in the sample mounting section 21. Figure 2 for others
Is the same as the sample holder shown in FIG. By using this sample holder, the angle of incidence of the primary ions could be changed, and measurement with high resolution in the depth direction could be performed under the condition that the surface was not roughened by sputtering.

[0020]

According to the present invention, the lower limit of the incident energy of the primary ions can be reduced to 0 without lowering the transmission efficiency of the mass spectrometer, especially when the primary ions and the secondary ions have the same polarity. It becomes possible. As a result, it is possible to perform high-level analysis with high resolution in the depth direction required for the development and evaluation of semiconductor devices and the like, and the measurement method is simple. Becomes possible.

Further, by providing the sample holder with a second sample mounting surface perpendicular to the secondary ion optical axis, the first sample is mounted on the second sample mounting surface perpendicular to the secondary ion optical axis. The incident position of the primary ions of the sample mounted on the sample mounting surface can be known, and the sample can be easily mounted in the direction perpendicular to the primary ion optical axis.

Further, by providing a position adjusting mechanism, samples of various sizes can be handled. Further, by providing the angle adjusting mechanism, it is possible to cope with a sample such that the front surface and the back surface of the sample are not parallel.

[Brief description of the drawings]

FIG. 1 is a diagram showing an arrangement of an analysis method according to the present invention.

FIG. 2 is a schematic view of a sample holder of the present invention.

FIG. 3 is a schematic view of another sample holder of the present invention.

FIG. 4 is a schematic view of another sample holder of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mass filter part 2 Primary column 3 Primary ion optical axis 4 Secondary column 5 Secondary ion optical axis 6 Secondary ion sector mass spectrometer and detector 7 Secondary ion extraction electrode 8 Sample analysis room 9 Gate valve 10 Reserve Exhaust chamber 11 Sample holder 12 XY stage 13 Sample 14 Secondary ion extraction voltage application power supply 15 Primary ion extraction voltage application power supply 16 Primary ion optical axis 17 Secondary ion optical axis 18 Front plate 19 Spring 20 Back plate 21 Sample mounting part 22 Plate Spring 23 Sample mounting part 24 Concave part 25 Sample position adjusting mechanism 26 Angle adjusting mechanism

Claims (6)

[Claims] 1. An analysis method using an oblique incidence type sector-type secondary ion mass spectrometer, wherein the normal direction of the sample is inclined from the direction of the secondary ion optical axis to the direction of the primary ion optical axis. Secondary ion mass spectrometry. 2. A sample holder of an oblique incidence type sector type secondary ion mass spectrometer, wherein a normal of a surface of a first sample mounting portion is inclined from a direction of a secondary ion optical axis to a direction of a primary ion optical axis. A sample holder. 3. The sample holder according to claim 2, wherein a surface of the first sample mounting section is perpendicular to a primary ion optical axis. 4. Adjacent to the surface of the first sample mounting portion,
The sample holder according to claim 2 or 3, wherein the sample holder has a surface of the second sample mounting portion perpendicular to the secondary ion optical axis. 5. The sample holder according to claim 2, wherein the sample holder has a mechanism for adjusting a position of the first sample mounting unit. 6. The sample holder according to claim 2, wherein said sample holder includes a mechanism for adjusting an angle of a surface of said first sample mounting portion.