JPH05290798A - Secondary ion mass spectrometer - Google Patents

Abstract

PURPOSE:To control a primary optical system by monitoring the shape of a primary ion beam. CONSTITUTION:When the shape of a primary ion beam radiated on a sample from an ion source 1 is examined, a beam shape sensor 11 is arranged in the position for a usual sample to be placed. The sensor has a number of point electrodes provided side by side with longitudinal and lateral intervals. When a beam hits the point electrodes, a beam current flows in the point electrodes and then is monitored with a primary optical system controller 10 to detect the shape of the beam. In accordance with the detection results, various parameters for a condenser lens 2, an objective lens 4 and the like are established with the controller 10 to make adjustment for the optimum shape of a beam.

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 having a primary ion beam shape monitoring function.

[0002]

2. Description of the Related Art Secondary ion mass spectrometer (Second)
ary Ion Mass Spectrometer
r: SIMS) is an analysis for identifying elements contained in a sample by irradiating the sample with a beam of primary ions such as oxygen, argon, and cesium and analyzing the mass of secondary ions generated from the sample. It is a means.

FIG. 4 is a schematic configuration diagram of a secondary ion mass spectrometer. When the primary ions are oxygen, an ion beam is generated by, for example, a duoplasmatron type ion source 1. The primary ion beam passes through a condenser lens 2, a deflector 3 that deflects the beam by about 2 ° to remove neutral particles, an electrostatic deflection plate 4 that scans the beam in the X and Y directions, and an objective lens 5. 6 is irradiated. Sample 6
The secondary ions generated from the electron beam pass through the electrostatic deflection energy analyzer 7 and the double focusing type or quadrupole type mass spectrometer 8
The output of the analyzer is amplified by a secondary electron multiplier or the like and input to the measuring device 9 to analyze the contained element of the sample 6.

[0004]

In the secondary ion mass spectrometer, the beam shape of the primary ions has a great influence not only on the analysis region of the sample but also on the analysis sensitivity and the resolution in the depth direction of the sample. .. Therefore, it is important to examine the shape of the primary ion beam when performing secondary ion mass spectrometry. Conventionally, regarding the investigation of the primary ion beam shape, after irradiating a dummy sample without deflecting and scanning the ion beam, the sample is taken out and the beam shape is judged from the shape of the crater formed by etching with the beam. It was Then, based on this determination result, the primary optical system controller 10 is operated so that the optimum beam shape can be obtained.
Therefore, the parameters of the primary ion optical system for the condenser lens 2, the objective lens 5 and the like are set and adjusted.

However, in order to carry out such an investigation, it is necessary to take out the sample from the analysis chamber under vacuum at any time, and if the irradiation time of the ion beam is added to the time required for this, the work will take a considerable time. It costs. Since the dummy sample may be destroyed during this work, it is necessary to have skill and experience in the investigation work together with the judgment of the etched crater.

The present invention is to provide a secondary ion mass spectrometer capable of detecting the shape of an ion beam without depending on a dummy sample and controlling the primary ion optical system according to the detection result. It is intended.

[0007]

In order to achieve such an object, the present invention provides an ion shape sensor having a large number of point electrodes arranged side by side at intervals in a secondary ion mass spectrometer, A primary optical controller for monitoring the beam current flowing through the point electrode of this sensor and setting the parameters of the primary ion beam optical system.

[0008]

According to the diameter of the primary ion beam, the area of the beam shape monitor where the point electrodes are struck by the beam changes, and a beam current flows through the point electrode where the beam hits. The shape of the primary ion beam can be determined by monitoring which point electrode the beam is hit by the primary optical system controller.
Based on the monitor result, the primary optical system controller is manually or automatically controlled to set various parameters of the primary ion optical system to set the shape of the primary ion beam to an optimum state.

[0009]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a portion related to the primary ion optical system, and the same reference numerals as those in FIG. 4 denote the same portions. The primary ion optical system includes an ion source 1 and a primary optical system controller 10.
The condenser lens 2, the deflector 3, the electrostatic deflection plate 4, and the objective lens 5 adjusted by. At the time of investigating the shape of the primary ion beam, a movable beam shape sensor 11 is arranged at a position where a sample is set. This beam shape sensor can be easily placed at the primary ion beam irradiation position when investigating the beam shape by, for example, being mounted on the back side of the manipulator operation table on which the sample is placed and held.

FIG. 2 is a plan view of the point electrode installation portion of the beam shape sensor 11 as seen from the ion beam irradiation side. In the same shape sensor, a large number of point electrodes 12 are arranged side by side vertically and horizontally, and each point electrode is connected to the primary optical system controller 10 by a conductor 13. The area of the point electrodes juxtaposed with the ion beam changes according to the size of the beam diameter φ, and when the beam hits, a beam current flows through the point electrode 12. The shape of the primary ion beam can be known by monitoring which point electrode 12 the beam is hit by the primary optical system controller 10. Based on this monitoring result, the primary optical system controller 10 is manually or automatically controlled to set various parameters of the primary ion optical system, and the shape of the primary ion beam is set to an optimum state.

The primary ion beam with which the sample is irradiated is usually in the form of a spot with a size of 100 μm or less, and the beam shape sensor 11 uses a technique generally used for processing a fine disk of a semiconductor, etching, sputtering, photo. It is manufactured by utilizing lithography, CVD (vapor phase growth method) or the like. FIG. 3 is an explanatory diagram of the configuration of the beam shape sensor 11, and FIG. 3A is a top view. The sensor 11 is formed on a ceramic insulating substrate 14 having a size of, for example, about 1 cm square, and the point electrodes 12 are arranged side by side in the central area of the substrate.
Is provided. A conductive wire 13 is provided around the insulating substrate 11.
A large number of terminals 16 for connecting the point electrodes 12 are provided, and each point electrode 12 is connected to a predetermined terminal 16 by a wiring 17. The upper surface of the insulating substrate 11 is a peripheral portion of the substrate and the point electrodes 1.
It is covered with an insulator 18 except for the portion 2.

To explain an example of manufacturing the beam shape sensor 11, a conductive metal such as aluminum or copper is vapor-deposited on the surface of the ceramic insulating substrate 14. Next, on the upper surface of this conductive metal, a large number of point electrodes 12 arranged in parallel in the central portion of the insulating substrate at intervals in the vertical and horizontal directions, their wirings 17, and terminals provided in the peripheral portion of the insulating substrate and connected to the conducting wire 13 are connected. 1
The portion to be 6 is masked with a resist. Etching is performed to remove the conductive metal in the portion not masked by the resist. The resist on the point electrode 12, the terminal 16 and the wiring 17 is removed by a remover. Above the point electrode 12 and the terminal 1
Covering the periphery of the insulating substrate 14 including 6 with a resist,
The insulator 18 is deposited on the entire surface of the insulating substrate not covered with the resist. The resist on the periphery of the point electrode 12 and the insulating substrate 14 is removed. FIGS. 3B and 3C are cross-sectional views of the point electrode forming portion and the terminal forming portion of the beam shape sensor 11 thus formed. The size and diameter of the point electrodes 12 are about 10 μm, and the arrangement interval is about 30 μm, and the number of them arranged in parallel is selected according to the maximum beam diameter.

[0013]

Since the present invention is configured as described above, the shape of the primary ion beam can be immediately detected on the spot, and as in the conventional case, a dummy sample can be removed from the analysis chamber at any time. The troublesome work of taking out and examining is no longer necessary, and the problem of destroying the dummy sample is gone. Then, by setting the parameters of the primary ion optical system manually or automatically based on the detection result from the beam shape sensor, the beam shape irradiated on the sample can be easily optimized. , High-sensitivity and high-accuracy analysis can be performed quickly.

[Brief description of drawings]

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

FIG. 2 is a plan view of a point electrode installation portion of a beam shape sensor.

FIG. 3 is an explanatory diagram of a configuration of a beam shape sensor.

FIG. 4 is a schematic configuration diagram of a secondary ion mass spectrometer.

[Explanation of symbols]

 1 Ion source 2 Condenser lens 3 Deflector 4 Electrostatic deflector 5 Objective lens 6 Sample 9 Measuring device 10 Primary optical system controller 11 Beam shape sensor 12 Point electrode 13 Conductor wire

Claims (1)

[Claims] 1. An ion shape sensor having a large number of point electrodes arranged vertically and horizontally at intervals, and a beam current flowing through the point electrodes of the sensor is monitored to set parameters of a primary ion beam optical system. A secondary ion mass spectrometer comprising a primary optical controller.