JPS60185351A - Charged particle beam control method - Google Patents

Abstract

PURPOSE:To perform observation of the specimen surface and analysis simultaneously by taking positive and negative beams alternatively as the primary charged particle beam while detecting the positive or negative ion selectively as the secondary charged particle signal to be emitted from the specimen. CONSTITUTION:Positive and negative pulse voltage are applied onto a charged particle source 1 such as a duoplasmatron encapsulated with argon to produce a positive ion beam of anode element and an electron beam of cathode element alternatively as the primary charged particle beam 13. Then it is irradiated alternatively onto a specimen 9 through a deflection electrode 15, a focus lens 5, an iris 2 and a beam separation iris 16 to detect the polarity of secondary charged particle flow 14 selectively through a deflection electrode 17 thus to display the secondary ion image and the secondary electron image simultaneously and independently onto CRT 12, 12'. Consequently, highly efficient observation of the specimen picture image and analysis of the specimen element with high resolution can be realized while the image observation and analysis can be performed simultaneously.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to charged particle beam control methods, and more particularly.

This relates to a charged particle beam control method in which a sample is irradiated with a charged particle beam extracted from a charged particle source, and a charged particle signal secondarily emitted from the sample is detected and used as sample analysis information9. High resolution sample surface observation using secondary ion images and secondary electron images.

It is applied to high-sensitivity mass spectrum analysis using secondary positive and negative ions.

[Background of the invention]

The prior art and its problems will be described with reference to FIG.

FIG. 1 shows a conventional example of a scanning ion microscope.

This device consists of a charged particle source (in this case an ion source)1. Aperture 2, 3, 4. , lens system 5, 6, 7° deflection electrode 8. Sample 9. Secondary charged particle detector 10. Scanning power supply 11. It is composed of a CRT (cathode ray tube) 12 for image observation. It uses a three-stage lens system.

This is to improve the reduction ratio, and a two-stage lens system may be used.

The operating principle is as follows. First, a primary charged particle (ion in this case) beam 1 is emitted from a charged particle source 1.
3 is made into a fine bundle using apertures 2, 3.4 and a lens system of 5°6.7, and is irradiated onto a sample 9. When the sample 9 is irradiated with the secondary charged particle beam 13, secondary charged particles (secondary pressure ions or secondary electrons) 14 based on sample atoms are emitted. The secondary charged particles 14 are detected by the charged particle detector 10 and used as a brightness modulation signal for the image observation CRT 12, so that a secondary ion image (or secondary electron image) on the surface of the sample 9 is observed. In this case, the beam scanning is performed by applying a voltage signal to the deflection electrode 8 from the scanning power source 11.
This is done in synchronization with CR'r12 for m.

However, with conventional methods, only one of positive ions, negative ions, and electrons can be used as a secondary charged particle beam from a charged particle source, so there is a problem that the amount of information obtained as a detection result is small. there were. In particular, when using specific ion species as the output of a charged particle detector, the dependence of secondary ion species on the secondary ion species is large, making it difficult to detect all sample elements with high sensitivity. There was a problem. In other words, when a positive ion species such as CK is used as the -order ion species, the negative -3= secondary ion strength of the negative element becomes high, but the secondary ion strength of the positive element, regardless of whether it is positive or negative, is significantly descend. - When a negative element is used as the secondary ion species, the relationship is completely opposite to the above.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems in the prior art, to alternately extract positive beams and negative beams as negative charged particle beams, and to generate secondary charged particle signals emitted from a sample by positive ions and negative ions. Alternatively, the sample surface can be observed with high resolution by detecting electrons arbitrarily and independently and selectively.

The object of the present invention is to provide a charged particle beam control method that enables high-sensitivity analysis and simultaneous performance of sample surface observation and analysis.

[Summary of the invention]

In the present invention, in order to achieve the above object.

The polarity of the electric field that extracts the beam from the charged particle source is periodically changed to alternately generate a charged particle beam due to positive elements and a charged particle beam due to negative elements, which are irradiated onto the sample and are emitted secondarily from the sample. Item 4 - A control method for selectively synchronizing the detection polarity conversion of the heavy particle signal with the polarity conversion of the beam extraction electric field. In this case, the detection polarity of the secondary charged particle signal is converted by detecting a secondary signal due to a positive element when irradiated with a charged particle beam due to a positive element, and detecting a secondary signal due to a negative element when irradiated with a charged particle beam due to a negative element. Synchronous conversion may be performed to detect secondary signals, and for both irradiation with a charged particle beam due to a positive element and irradiation with a charged particle beam due to a negative element, the secondary signal due to the positive element and the negative element Synchronous conversion may also be performed to independently and selectively detect the secondary signal due to the

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG. This is an example in which a scanning electron image and a scanning ion image are observed simultaneously. The device includes a charged particle source 1. Aperture 2.3, 4. - Lens for secondary charged particle beam focusing 5.6.7 (including the case of a combination lens of magnetic field and electrostatic field), deflection electrode 8. Sample 9. A positively charged particle detector 10, a negatively charged particle detector 10', a scanning power source 11. CRT 12 for positively loaded particle image observation, CRT 1.2' for negatively charged particle image observation, and deflection electrode 15 for -order beam planking. Aperture for beam separation 16. Deflection electrode 17 for secondary signal separation. Secondary signal separation aperture 18. It is composed of an acceleration high voltage power supply 19 and a divided voltage power supply 20.

The embodiment of FIG. 2 operates as follows. A duoplasmatron with argon introduced was used as the charged particle source 1. As shown in Figure 3, positive and negative pulse voltages are applied to this charged particle source to generate a charged particle (positive ion) beam of positive elements and a charged particle (electron beam or negative ion beam) of negative elements. Pull out alternately. For argon plasma.

The amount of negative ions is extremely small and can be ignored compared to the amount of electrons. The extracted charged particle beam 13 is.

Deflection electrode 15 and focusing lens 5. The diaphragm 2 and the beam separation diaphragm 16 periodically separate the beam into a positive ion beam and an electron beam, which are extracted below the diaphragm 16 . That is, the sample 9 is alternately irradiated with a positive ion beam and an electron beam. In this case, by using a magnetic field lens together with a certain lens system of the focusing lens system, the diameter of the electron beam can be made more narrow. In this example, the lens 6.7 was used as a hybrid lens that can be used as both an electrostatic lens and a magnetic field lens. That is, for positive ions, two-stage electrostatic I-nones 5 and 7 (the electrostatic lens 6 is not operated) are used, and for electrons, electrostatic charges are applied in synchronization with the polarity change of the accelerating voltage. Turn off the lens.

A three-stage magnetic field lens was used. As a result, the ion beam diameter and electron beam diameter on the sample are respectively 177
ffl and O,], //II+ were obtained.

On the other hand, positive and negative detection of the secondary charged particle flow 14 generated on the sample surface by the irradiation with the -order charged particle beam is selectively performed by the deflection electrode 17. In this embodiment, as described above, a positive ion beam and an electron beam are used alternately as the primary beam, and secondary pressure ions and secondary electrons are used as the secondary signals, respectively, so that a secondary ion image and a secondary With electronic images.

CRT for image observation], 2 and 12' can be observed simultaneously and independently. The primary excitation source in this case.

7- Displaying secondary signal selection, information type and characteristics and as shown in Table 1.

We have described the case where a secondary ion image and a secondary electron image are observed simultaneously and independently using a CRT12.12'.
According to the present invention, by using a mass spectrometer as one or both of the detection systems of the positive and negative charged particle detectors 10° 10' and the positive and negative image observation CRTs 12 and 12', image observation using the CRT It is also possible to simultaneously perform spectral analysis using a mass spectrometer, or perform mass spectral analysis of secondary pressure and negative ions at the same time. secondary pressure,
Table 2 shows the primary excitation source, secondary signals, types of information, and their respective characteristics when performing mass spectrometry analysis using negative ions.

8- Selectively synchronize the polarity and detection polarity of the secondary signal.

It becomes possible to independently and selectively detect a positive or negative secondary signal for the excitation of a positive ion beam, and a positive or negative ion or electron secondary signal for the excitation of negative ions or electrons, respectively, This has the advantage of enabling highly efficient observation of a sample surface image, high resolution analysis of sample elements, and simultaneous execution of image observation and analysis.

〔Effect of the invention〕

According to the present invention, (1) the amount of information can be doubled compared to conventional methods, thereby enabling more accurate sample evaluation. (2) Positive ions, negative ions, or electrons can be extracted and used as secondary signals, making it possible to observe the sample surface with high resolution and analyze the sample with high sensitivity, and to select information as necessary. . (3) A second-class effect is achieved that enables simultaneous analysis in different modes, such as performing image observation and analysis at the same time.

[Brief explanation of the drawing]

Fig. 1 is a layout diagram of a conventional scanning electron microscope, and Fig. 2 is a scanning electron microscope using the control method of the present invention. , 1.6... Aperture 5.6.7... Lens 8.15... Deflection electrode 9... Sample 10, 10'... Charged particle detector 11... Scanning power source 12, 12 '...CRT I3...-Secondary charged particle beam 14...Secondary charged particle flow 17...Deflection electrode for secondary signal separation 18...Aperture for secondary signal separation 19...High voltage for acceleration Power supply 20... Partial voltage power supply agent Junnosuke Nakamura Figure 3 Positive voltage Snow Negative voltage C1

Claims (4)

[Claims] (1) In a charged particle beam control method in which a sample is irradiated with a charged particle beam extracted from a charged particle source and a charged particle signal secondarily emitted from the sample is detected and used as sample analysis information, By periodically changing the polarity of the electric field that extracts the beam from the sample, a charged particle beam from a positive element and a charged particle beam from a negative element are alternately generated and irradiated onto the sample, and the charged particles are secondarily emitted from the sample. A charged particle beam control method characterized in that the conversion of the detection polarity of a signal is performed selectively in synchronization with the polarity conversion of a beam extraction electric field. (2) Conversion of the detection polarity of the secondary charged particle signal. polarity conversion of the beam extraction electric field so as to detect a secondary signal due to a positive element when irradiated with a charged particle beam due to a positive element, and to detect a secondary signal due to a negative element when irradiated with a charged particle beam due to a negative element; 2. A charged particle beam control method according to claim 1, wherein the charged particle beam control method is carried out according to the following. (3) Conversion of the detection polarity of the secondary charged particle signal. The secondary signal due to the positive element and the secondary signal due to the negative element are independently and selectively detected for both the irradiation with the charged particle beam due to the positive element and the irradiation with the charged particle beam due to the negative element. A charged particle beam control method according to claim 1, characterized in that the charged particle beam control method is carried out in response to polarity conversion of a beam extraction electric field. (4) Conversion of the detection polarity of the secondary charged particle signal. - detecting a secondary signal for image observation of the sample surface and a secondary signal for sample elemental analysis as secondary signals from the sample when the sample is irradiated with the secondary charged particle beam; 2. A charged particle beam control method according to claim 1, wherein said charged particle beam control method is carried out in response to polarity conversion of a beam extraction electric field.