JPH03251760A - Beam analysis method and ion beam processing method - Google Patents

Abstract

PURPOSE:To prevent the accumulation of negative charge on an insulating sample by irradiating the insulating sample with specific ion beam along with electron beam. CONSTITUTION:When the surface of an insulating sample 5 is irradiated with electron beam 11 by an electron gun 1, an Auger electron 31 is generated from the sample 5 to be detected by a detector 3 and the kinetic energy of the electron 31 is analyzed to analyze the element in the sample 3. When the sample is also irradiated with the ion beam 41 of an He<+> ion due to an ion gun 4 simultaneously with the irradiation with the beam 11, the beam neutralizes charge without generating sputtering action and no Auger electron or specific X-rays is formed and the accumulation of negative charge on the surface of the sample 5 is prevented and precise beam analysis or ion beam processing can be carried out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for preventing static electricity when surface analysis is performed by irradiating an insulating sample with an electron beam, and a method for performing an electron beam process on an insulating sample by beam processing. This article relates to a method for preventing static electricity during mirror observation.

[Conventional technology]

Auger electron spectroscopy, X-ray microprobe analysis methods, and scanning electron microscopy surface observation methods involve irradiating a sample with an electron beam, detecting Auger electrons or characteristic X-rays emitted from the sample, and measuring the kinetic energy of the electrons or X-rays. The elements contained in the sample are analyzed by analyzing the energy of the sample, or the surface of the sample is observed by detecting and amplifying the secondary electrons emitted from the sample. It is also possible to obtain the distribution of the elements contained in the sample in the depth direction by repeating the method of analyzing the surface by sputtering.Furthermore, the insulating sample is microfabricated with an ion beam of Ar or Ga ions. Surface observation can also be performed during ion beam processing.In these beam analysis methods and ion beam processing methods, in order to irradiate the sample surface with an electron beam, an insulating material (insulating sample) or a sample surrounded by an insulating material is used. In this analysis, charge-up (electrification) changes the kinetic energy of the irradiated electron beam and the emitted secondary electrons 9 reflected electrons, making accurate analysis difficult. Particles, in this case electron beams, cause charge to accumulate within the sample, which is caused by electrons emitted from the sample, such as reflected electrons, secondary electrons, and Auger lives to become more.

To prevent charge-up, lower the accelerating voltage and current of the irradiated electron beam. ■Tilt the sample. ■Covering the sample surface with a metal mesh mask
Methods such as (1) irradiation with an ion beam (Japanese Unexamined Patent Publication No. 63-37551), and (2) applying a conductive IS coating (for surface observation) are used.

[Problem to be solved by the invention]

However, in method (2) in the conventional technique for preventing charge amplifiers, the accelerating voltage and current are low, so the sensitivity of the detected Auger electrons or the characteristic x&ll is low and the signal-to-noise ratio is poor. Or the resolution of surface observation decreases. In method (2), analysis of minute areas is impossible due to the tilt. In Method 2, if the mesh is large, it will charge up, and if it is small, when Ar'' ions are used to spatter the contained elements in the depth direction, the metal in the mesh will also spatter and adhere to the sample, making it difficult to obtain correct information. In addition, the method of irradiating with Ar'''' ions disclosed in JP-A No. 63-3755 (Method 2) causes spattering on the outermost surface, making it difficult to analyze the surface of ultra-thin films. I can't get the correct information.

There is also the problem that when ^r'''' ions are irradiated, Auger electrons and characteristic X-rays of Ar are observed. Furthermore, in method ■, the thin film disappears in the area that has undergone ion beam processing.
There was a problem that the antistatic effect was lost.

The present invention has been made in view of the above points, and its purpose is to provide a beam analysis method and an ion beam processing method that can perform correct elemental analysis or correct surface observation of an insulating sample without accumulating negative charges on the sample. According to the present invention, the above objects are to provide: 1) irradiating a sample with an electron beam 11 and analyzing the kinetic energy of Auger electrons 31 emitted from the sample; In a beam analysis method for analyzing elements contained in a sample, the insulating sample 5 is irradiated with an ion beam 41 of He''' ions or H0 ions at the same time as an electron beam, 2) the sample is irradiated with an electron beam 52, In a beam analysis method in which elements contained in a sample are analyzed by analyzing the energy of characteristic X-rays 55 emitted from the sample, He'''
3) irradiate the sample with an ion beam 62 of ions or H4 ions at the same time as an electron beam; 3) irradiate the sample with the electron beam 80; detect and amplify the secondary electrons 81 or backscattered electrons 82 emitted from the sample to determine the fine structure of the sample; In the beam analysis method for observation, He'' ions or H0 ions are applied to the insulating sample 76.
An ion beam 83 of ions is irradiated simultaneously with an electron beam, and 4
) In a beam analysis method in which a sample is irradiated with an electron beam 96 and the kinetic energy of Auger electrons 99 emitted from the sample is analyzed to analyze the elements contained in the sample, an insulating sample 95 is irradiated with gamma rays 97 with an electron beam. 5) In a beam analysis method in which the sample is irradiated with the electron beam 107 and the kinetic energy of the Auger electrons 10B emitted from the sample is analyzed to analyze the elements contained in the sample, the insulating sample 105 6) Irradiate the sample with electrons &1107 and analyze the kinetic energy of Auger electrons 108 emitted from the sample. In a beam analysis method for analyzing elements contained in a sample, an insulating sample 110 having an uneven surface is irradiated with an electron beam, or 7) an ion beam for processing 159 is irradiated on the insulating sample, In an ion beam processing method in which fine processing is performed and the processed shape is observed by scanning the electron beam 160, by irradiating an insulating sample with an ion beam 161 of He'' ions or H0 ions at the same time as the electron beam 160. achieved.

[Effect]

He'' ions and H4 ions neutralize charges without sputtering. They also do not generate Auger electrons or characteristic X-rays. When the electron beam is incident on the sample at an acute angle, the secondary electrons Since the γ-rays are generated from a shallow region, there is a high probability that secondary electrons will jump out from the sample, and the sample will become positively charged.When an insulating sample is irradiated with gamma rays, secondary electrons are emitted from the sample surface and become positively charged. remains on the sample surface. When the sample has irregularities, the frequency of incidence of the electron beam at acute angles increases, and negative charging is prevented.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a layout diagram showing an Auger electron spectrometer according to an embodiment of the invention as defined in claim 1.

An electron beam 11 is focused and irradiated onto a sample 5 from an electron gun 1 by a lens system 2, and Auger electrons 31 emitted thereby are detected by a detector 3. An ion beam 41 consisting of the 1lHe'' ions is irradiated onto the sample from the ion gun 4 at the same position as the electron beam.

The irradiation conditions for He'' ions are as follows.

Acceleration voltage: 1kV Emission current 7 10mA Gas pressure' 2.6 Xl0-'' Pa Irradiation area: 200 J111
Auger electrons with the correct energy can be detected.

FIG. 2 is a diagram showing an Auger electron spectrum according to an embodiment of the invention defined in claim 1 for a magnesium oxide 01g0) sample, and FIG. 3 is a diagram showing a conventional Auger electron spectrum of a MgO sample. .

The spectrum in Figure 2 is a normal spectrum when irradiated with He'' ions, with charge-up being prevented.In other words, the energy value of the spectrum is correct and large.On the other hand, the spectrum in Figure 3 shows IIs'' ions. Since there is no irradiation, the sample is charged up, and the electron spectrum shifts to the higher energy side. The peak value is small, and many small secondary peaks appear around the main peak. Depending on the sample, the main peak may disappear. Secondary peak values interfere with the spectra of other elements.

A similar effect can be obtained when using H4 ions in addition to He'' ions as an ion source.The advantage of H+ ions is that
The specific bus battering rate for e-ions is as low as approximately 172, and there is little spatter on the sample surface, making it particularly suitable for analysis of the outermost surface.

FIG. 4 is a layout diagram showing an X-ray microanalyzer according to an embodiment of the invention defined in claim 2.

An electron beam 52 emitted from the electron gun 51 is focused by a 171 magnetic lens 53 and irradiated onto a sample 54 . Characteristic X-rays 55 excited within the sample 54 by this electron beam 52
is separated into spectra according to the wavelength of the characteristic X-ray 55 by the spectroscopic crystal 56, and detected by the X-ray detector 57. At this time, the electron beam 52 can also scan the surface of the sample 54 two-dimensionally by means of an electromagnetic lens 53. The same area on the surface of the sample 54 that is irradiated with this electron beam 52 is
(Irradiation with a 1” ion beam 62.The ion source 59 is
It is connected to a He gas cylinder 61 through a pressure regulator 60.

IJ5wJ is a diagram showing the X-ray spectrum of aluminum nitride (AjN) according to the embodiment of the invention defined in claim 2, where the horizontal axis represents the X-ray detection position according to the X-ray wavelength;
That is, the distance between the sample and the spectroscopic crystal or between the spectroscopic crystal and the X-ray detector, and the vertical axis indicates the X-ray intensity.The analysis conditions at this time are as follows.

Electron beam acceleration voltage: 10kV Electron beam current: lXl0-”A spectroscopic crystal,
STE (stearate) ion beam acceleration voltage: tkv Helium (Ha) gas pressure: 3 Xl0-”Pa 5th
As shown in the figure, even though aluminum nitride is an insulator, the negative charge of the electron beam is neutralized by irradiation with the He'' ion beam, resulting in the first-order diffraction of the alpha rays of nitrogen.
NKα (■)) and α of aluminum, 4th order diffraction line (A
fKα, (IV)) can be stably detected.

In contrast, Fig. 6 shows the X-ray spectrum obtained when a thin platinum film was coated on the sample surface to prevent static electricity.
MαI(V)) are in close proximity to each other, making it difficult to separate and perform quantitative analysis. In this way, there are many examples of combinations that are interfered with by metals deposited to prevent static electricity, such as oxygen and gold, carbon and copper, and boron and silver. Although this may be difficult, the antistatic method using He" ion beam irradiation eliminates such concerns.

Similar results can be obtained when an H+ ion beam is used instead of the He'' ion beam.

He'' and H+ ion beams have a small mass number, so A
Unlike r'' ions, there is very little risk of deforming or altering the sample surface due to sputtering action, and since no characteristic X-rays are generated, the ion beam itself does not interfere with analysis.

FIG. 7 is a layout diagram showing a scanning electron microscope according to an embodiment of the invention as defined in claim 3. An electron beam 80 is focused and irradiated by a lens system 72 from an electron gun 71 onto an insulating sample 76, and secondary electrons 81 or reflected electrons 82 emitted thereby are detected by detectors 73 and 74, respectively.

At this time, an ion beam 83 consisting of He' ions is irradiated from the ion gun 75 onto the sample at the same position as the electron beam. 7B
is a pressure regulator, 77 is a gas cylinder, and 79 is an exhaust device. Electrostatic charging on the sample surface is prevented, making it possible to accurately observe the fine structure of insulating samples, which has been difficult to observe in the past. A similar effect can be obtained when H'''' ions are used as an ion source in addition to He'''' ions.

For example, the observation conditions when observing quartz (Slot) with a thickness of 1 m are as follows.

Electron beam acceleration voltage: , 15 to νElectron beam current: I
I Xl0-"Pa FIG. 14 shows a photograph of the crystal structure of quartz. FIG. 1 is a photograph of a crystal structure according to an example.
In Figure 4(a), the image is distorted, but in No. 14l-), a correct image is obtained.

As another example, observation conditions for 5rTiOs are as follows.

Electron beam acceleration voltage: 15kV Electron beam current: I
I Xl0-''Pa FIG. 8 is a layout diagram showing an Auger electron spectroscopy apparatus according to an embodiment of the invention defined in claim 4.

An electron beam 96 is focused from an electron gun 91 onto an insulating sample 95 by a lens system 92 and irradiated perpendicularly to the sample, and Auger electrons 99 emitted thereby are detected by a detector 93.
At this time, gamma rays 97 are irradiated onto the sample surface from a gamma ray source 94.

100 is an exhaust device.

The following sources are used for gamma rays.

r&ll standard source,! Strength of 41A plow source: 3.7 Distance M between sample surfaces of XIO”BQ (Becquerel) source: 10-50
l-) is a diagram showing the Auger electron spectrum according to the embodiment of the invention defined in claim 4, where the sample is sapphire.
(A7.0., R surface, Mirror Polish 11) was used. 9th
FIG. 1a) is a diagram showing a conventional Auger electron spectrum using the sample. The spectrum of Fig. 9011) is γ
When irradiated with radiation, charge-up is prevented and a normal spectrum can be obtained. That is, the energy value of the spectrum is correct and the intensity is large. Here, the distance between the gamma ray source and the sample surface is determined by turning the handle 98 to the position where the intensity of oxygen is maximum, for example, while looking at the obtained spectrum. Adjusted. On the other hand, since the spectrum shown in Figure 9 (Tsukasa) is not irradiated with gamma rays, it is charged up and a normal spectrum cannot be obtained.

In addition to 341A- as a standard gamma ray source, %j Co.

Of course, the same effect can be obtained when +s sB, i, t st(, -.Co is used.

The advantage of Dew 41^- is that the γ-ray energy is 26 keV, 60
Because of the low keV, ■ rllA is almost 1 near the sample surface.
As a result, secondary electrons are also generated near the surface of the sample, which makes them easier to emit from the surface, accumulating positive charges, and preventing charge-up is easier than with other radiation sources. ■There is no leakage from the Auger device to the outside, and even if the gamma ray source is taken out for repairs, it will not affect the human body if it is stored in a lead container with a thickness of 2 to 3 mm.In addition, ■Half-life is 470 years Because it is extremely long, the strength of γ is always stable.
Lines can be irradiated. In addition to gamma rays, alpha rays can also be used as radiation to prevent negative charging. '4■^- is 5.4
Since it emits 8 MeV alpha rays, it is effective in preventing negative charging.

FIG. 1O is a layout diagram showing an Auger electron spectrometer according to an embodiment of the invention defined in claim 5.

Electrons M107 are focused and irradiated by a lens system 102 from an electron gun 101 onto an insulating sample 105, and Auger electrons 10B emitted thereby are detected by a detector 103.

106 is an exhaust device. At this time, the stage 104 having a sample tilting function is tilted so that the electron beam is incident at an acute angle, and secondary electrons are emitted. After positively charging the sample surface, by returning the sample to the direction of 90 degrees to the electron beam,
Charge-up of the sample surface due to the electron beam is prevented, and Auger electrons with the correct energy can be detected.

Fig. 11 1a) is a diagram showing the Auger electron spectrum according to the embodiment of the invention defined in claim 5 for a quartz plate (Sin) sample; Fig. 11 is a diagram showing the Auger electron spectrum in a positively charged state. The spectrum in Fig. 11 (bl) is shifted to the lower energy side because the sample surface is positively charged due to secondary electron emission. ing.

FIG. 12 is a cross-sectional view showing a sample according to an embodiment of the invention defined in claim 6, in which about 10 particles of sand made of silicon carbide with a particle size of 1- or less are sprayed onto the surface of the sample. IJIIl unevenness is formed. In the Auger electron spectrometer shown in Fig. 10, when the uneven surface of the sample 110 is irradiated with an electron beam instead of the sample 105, the emitting effect of secondary electrons is enhanced, charge and up are less likely to occur, and Auger electrons with the correct energy distribution are produced. It becomes possible to detect. It is sufficient to form the unevenness only in the analysis part. FIG. 13 shows the Auger electron spectrum of the sample thus obtained.

Figure 13 shows strontium titanate (SrTiOs)
Fig. 13 shows the Auger electron spectrum of the sample.
is a diagram showing the Auger electron spectrum of a conventional sample whose surface is not roughened and which is in a charged-up state. Due to the accumulation of negative charges on the sample, a correct spectrum cannot be obtained. FIG. 13-) is a diagram showing the Auger electron spectrum according to the embodiment of the invention defined in claim 6. Charge-up is prevented, and a normal spectrum (Auger peak position of oxygen is 512 eV) is obtained.

FIG. 15 is a layout diagram showing an ion beam processing apparatus according to an embodiment of the invention defined in claim 7.

The insulating sample 155 is micro-processed using the processing ion beam 159 . A finely focused electron beam 160 is irradiated onto an insulating sample 155 from an electron gun 152, and the secondary electrons 162 emitted at this time are irradiated by a secondary electron detector 153. This method prevents the surface of the sample from being electrically charged, making it possible to accurately observe the fine shape of an insulating sample, which has been difficult to observe in the past.

A similar effect can be obtained when H'' ions are used as an ion source in addition to He''' ions.

For example, the observation conditions when observing quartz (SiOx) having a thickness of l+w are as follows. Note that the influence of the ion beam for micromachining is relatively small and can be substantially ignored.

Electron beam acceleration voltage: 15kV Electron beam current: I
I In the analysis method, an ion beam of He'' ions or H° ions is irradiated onto an insulating sample at the same time as an electron beam, and 2) the sample is irradiated with an electron beam and the energy of the characteristic X-rays emitted from the sample is analyzed. In the beam analysis method for analyzing elements contained in a sample,
3) Irradiate an ion beam of He''' ions or H0 ions onto an insulating sample at the same time as an electron beam; 3) Irradiate the sample with an electron beam, detect and amplify secondary electrons or backscattered electrons emitted from the sample, and In the beam analysis method for observing microstructures, H is applied to an insulating sample.
4) Irradiate the sample with an ion beam of e" ions or H3 ions at the same time as an electron beam, and analyze the kinetic energy of Auger electrons emitted from the sample to analyze the elements contained in the sample. In the beam analysis method, an insulating sample is irradiated with gamma rays at the same time as an electron beam, and 5) the sample is irradiated with an electron beam and the kinetic energy of Auger electrons emitted from the sample is analyzed to analyze the elements contained in the sample. In the beam analysis method, an electron beam is incident on an insulating sample at an acute angle, and then an electron beam is incident on the insulating sample perpendicularly to perform elemental analysis. In the beam analysis method, which analyzes the kinetic energy of Auger electrons generated in the sample to analyze the elements contained in the sample, an insulating sample with an uneven surface is irradiated with an electron beam, or 7) an insulating sample for processing. In the ion beam processing method, which performs fine processing by irradiating an ion beam and observing the processed shape by scanning an electron beam, a beam H is applied to an insulating sample.
Since the ion beam of e" ions or H0 ions is irradiated with the electron beam at the same time, the outermost surface of the insulating sample is neutralized by the He" ions or H4 ions without being sputtered, and as a result, the elements on the outermost surface are It becomes possible to perform analysis and surface observation accurately. In addition, it is possible to improve the precision of ion beam processing based on accurate surface observation.* He" ions and H0 ions do not generate Auger electrons or characteristic X-rays, which also increases the accuracy of elemental analysis.*
Contamination on the sample surface is removed by He'' ions and H+ ions, making it possible to always observe a clean sample surface.Also, simultaneous irradiation with TwA allows the electron beam to be incident on the sample surface at an acute angle and then incident vertically. By doing so, or by irradiating the rough surface with an electron beam to eliminate negative charge, it becomes possible to perform elemental analysis accurately. Irradiation with γ-rays makes the secondary electron image clearer.

[Brief explanation of drawings]

FIG. 1 is a layout diagram showing an Auger electron spectrometer according to an embodiment of the invention defined in claim 1, and FIG. 2 shows an Auger electron spectrum of an MgO sample according to an embodiment of the invention defined in claim 1. What is the line diagram shown in Figure 3? FIG. 4 is a diagram showing the conventional Auger electron svector of a 1gO sample, FIG. 4 is a layout diagram showing an X-ray microanalyzer according to an embodiment of the invention defined in claim 2, and FIG. A diagram showing the X-ray spectrum according to the embodiment of the invention defined in FIG.
A diagram showing a conventional X-ray spectrum of a sample, FIG. 7 is a layout diagram showing a scanning electron microscope according to an embodiment of the invention defined in claim 3, and FIG. 8 is a diagram showing the invention defined in claim 4. FIG. 9 shows the Auger electron spectrum of sapphire, FIG. 9 tal is a diagram showing the conventional Auger electron spectrum, and FIG. 10 is a diagram showing the Auger electron spectrometer according to the embodiment of the invention defined in claim 5, FIG. 11 is a diagram showing the arrangement of the Auger electron spectrometer according to the embodiment of the invention defined in claim 5, and FIG. The Auger electron spectrum of the sample is shown, and FIG. 11 (al is a diagram showing the Auger electron spectrum according to the embodiment of the invention defined in claim 5, and FIG. 11) is a diagram showing the conventional Auger electron spectrum. , FIG. 12 is a cross-sectional view showing a sample according to an embodiment of the invention defined in claim 6, FIG. 13 shows an Auger electron spectrum of 5rTiOz, and FIG. 13 (11) shows a conventional Auger electron spectrum. Diagram, Figure 13 (b
l is a diagram showing the Auger electron spectrum according to the embodiment of the invention defined in claim 6, FIG. 14 is a photograph of the crystal structure of quartz, and FIG. Figure 14) is a photograph of the crystal structure according to the embodiment of the invention defined in claim 3, and Figure 15 is a layout diagram showing the ion beam processing apparatus according to the embodiment of the invention defined in claim 7. be. 11.52. Bo, 107: Electron beam, 31,99.1
087 Augier Electronics, 5,54.76.95,105.
110: Insulating sample, 41, 62° 83: Ion beam, 97: γ-ray, 55: Characteristic X-ray, 81: Secondary electron, 8
2: Backscattered electron, 159: Ion beam for processing, 160:
Electron beam, 161: Ion beam. Fig. 2 Fig. 1 Energy degree ■) Fig. 3 Fig. 5 Fig. 6 Fig. 7 Fig. 10 Fig. 1 Channel'("(eV) Fig. 11 Electric 9 east Figure 15

Claims (1)

[Claims] 1) In a beam analysis method in which elements contained in the sample are analyzed by irradiating the sample with an electron beam and analyzing the kinetic energy of Auger electrons emitted from the sample, He^ is applied to an insulating sample. A beam analysis method characterized by irradiating an ion beam of + ions or H^+ ions simultaneously with an electron beam. 2) Characteristics X emitted from the sample by irradiating the sample with an electron beam
In the beam analysis method, which analyzes the energy of a ray to analyze the elements contained in a sample, He^ is applied to an insulating sample.
A beam analysis method characterized by irradiating an ion beam of + ions or H^+ ions simultaneously with an electron beam. 3) In the beam analysis method, in which the sample is irradiated with an electron beam and the secondary electrons or reflected electrons emitted from the sample are detected and amplified to observe the fine structure of the sample, H
A beam analysis method characterized by irradiating an ion beam of e^+ ions or H^+ ions simultaneously with an electron beam. 4) In the beam analysis method, which analyzes the elements contained in the sample by irradiating the sample with an electron beam and analyzing the kinetic energy of Auger electrons emitted from the sample, γ-rays are irradiated onto an insulating sample at the same time as the electron beam. A beam analysis method characterized by: 5) In the beam analysis method, in which the elements contained in the sample are analyzed by irradiating the sample with an electron beam and analyzing the kinetic energy of Auger electrons emitted from the sample, the electron beam is incident on the insulating sample at an acute angle, A beam analysis method is characterized in that an electron beam is then perpendicularly incident on an insulating sample to perform elemental analysis. 6) In the beam analysis method, in which the elements contained in the sample are analyzed by irradiating the sample with an electron beam and analyzing the kinetic energy of Auger electrons emitted from the sample, the electron beam is applied to an insulating sample with an uneven surface. A beam analysis method characterized by irradiating. 7) In the ion beam processing method in which an insulating sample is irradiated with a processing ion beam to perform microfabrication and the processed shape is observed by scanning the electron beam, the insulating sample is exposed to He
An ion beam processing method characterized by irradiating an ion beam of ^+ ions or H^+ ions simultaneously with an electron beam.