JPH0745227A - Charged-particle-applying analyzer and charged-particle-applying plotter - Google Patents

Abstract

PURPOSE:To provide a scanning electron microscope(SEM) by which an image of a recess and projection pattern on a surface of a sample can be displayed clearly by preventing accumulation of an electron beam (incident electric charge). on the surface of the sample (semiconductor substrate). CONSTITUTION:A vacuum vessel 31 added outside of a vacuum tank 2 in which a sample 1 is arranged so as to generate plasma 38, is provided. Incident electric charge is neutralized by the plasma 38 on a surface of the sample 1 to be analyzed by radiation of an electron beam 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle application analysis apparatus and a charged particle application drawing apparatus, for example, a scanning electron microscope (SEM) and a transmission electron microscope (TEM).
oscope) and Auger electron spectroscopy (AES)
tron Spectroscopy) Secondary ion mass spectrometer (SIM
S; Secondery Ion Mass Spectroscopy), and also measures for preventing charge-up on the sample surface in a focused ion beam drawing apparatus, an electron beam exposure apparatus, and the like.

[0002]

2. Description of the Related Art First, a typical ion implanter as a conventional charged particle application apparatus will be described. FIG. 3 is a schematic view showing a structure of a portion near a semiconductor substrate of a conventional ion implantation apparatus. In the figure, 1 is a semiconductor substrate placed in a vacuum chamber 2 and 3 is an ion beam incident on the semiconductor substrate 1. Reference numeral 4 denotes a vacuum pump for exhausting the inside of the vacuum chamber 2 so that the gas pressure in the vacuum chamber 2 becomes a predetermined vacuum degree.

Next, the operation will be described. The vacuum chamber 2 is evacuated by the vacuum pump 4 to a degree of vacuum at which the scattering of the ion beam 3 can be ignored. In this state, the vacuum chamber 2
The ion beam 3 is irradiated onto the semiconductor substrate 1 disposed inside, and thus the ion implantation into the semiconductor substrate 1 is performed.

FIG. 4 is a schematic diagram showing the structure of a scanning electron microscope (SEM) as another example of the conventional charged particle application apparatus. In the figure, 10 is an SEM for analyzing a sample 1 such as a semiconductor wafer or a semiconductor chip, and 11
Is an electron gun, 12 is a focusing lens for focusing the electron beam (charged particles) 3a emitted from the electron gun 11, 13 is an objective lens for focusing the focused electron beam on a sample, and 15 is for deflecting the focused electron beam. Deflection plate for, 14 is the sample 1
The secondary electron detector 16 for detecting the secondary electrons 3b emitted from the detector 16 is a mounting table on which the sample 1 such as the semiconductor substrate is arranged, and the secondary electron detector 14 and the mounting table 16 are inside the vacuum chamber 2. It is located in. Here, the vacuum chamber 2 is shown in FIG.
It has the same structure as that of the ion implantation apparatus shown in (3), and the inside thereof is exhausted by a vacuum pump (not shown).

In the SEM 10 having such a configuration, the sample 1
Image processing is performed based on the secondary electrons 3b emitted from the sample 1 by the scanning with the electron beam 3a above, and the concavo-convex pattern on the sample surface is displayed on the screen.

FIG. 5 is a diagram showing the configuration of a focused ion beam drawing apparatus as still another example of a conventional charged particle application apparatus, in which 20 is a sample surface irradiated with charged particles to obtain a sample surface. A focused ion beam drawing apparatus which draws a predetermined pattern on the ion beam source 21 includes an ion source 21 and an ion beam (charged particles) 4 emitted from the ion source 21.
It is an accelerating electrode that accelerates a. Further, 12 is a focusing lens for focusing the accelerated ion beam 4, 13 is an objective lens for focusing the focused ion beam 4a on the sample, 15 is a deflection plate for deflecting the focused ion beam 4a, and 2 is a vacuum pump (Fig. A vacuum chamber configured to evacuate by (not shown), and 16 is a mounting table on which the sample 1 such as the semiconductor wafer is placed. Here, the mounting table 16 is in a predetermined plane by a moving mechanism (not shown). It is configured to be movable.

In the focused ion beam drawing apparatus 20 having such a structure, for example, the mounting table 16 is moved so as to correspond to the chip area of the semiconductor wafer, and the mounting table 16 is positioned, and then the ion beam 4a is applied to the semiconductor. Irradiation is performed while scanning on a predetermined chip area of the wafer 1, and a predetermined pattern is drawn on the chip area. When the drawing of one chip area is completed, the chip table adjacent to the mounting table 16 is moved to a position where drawing is possible, and a pattern is drawn in the same manner as described above. In this way, the chip areas are sequentially drawn, and the entire chip area of one semiconductor wafer is drawn.

[0008]

However, the conventional SE
In a charged particle application apparatus such as M or a focused ion beam drawing apparatus, incident charges are accumulated in a region of an insulator such as a photoresist on the surface of a semiconductor substrate, a high electric field is generated, and it is already formed on the semiconductor substrate. There was a problem that the electronic circuit was destroyed.

In the SEM 10, for example, when observing the shape of an insulating film formed on a Si wafer, electrons do not flow into the substrate side and the surface of the insulating film is charged up. , The image may disappear. In order to avoid this, a method of depositing a conductive material such as Au or C on the surface of the sample thinly (about 10 nm) and observing has been used for a long time, but this method has a drawback that in-line observation is not possible.

Further, in the focused ion beam drawing apparatus 20, the surface of the insulating film such as photoresist is charged, so that the ion beam is affected by the electric field thereof, making it difficult to draw a fine pattern with high accuracy. There is a problem such as.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to prevent the accumulation of incident electric charges and thereby display an image of a concavo-convex pattern on the surface of the sample clearly. The purpose is to obtain a charged particle application analyzer.

Another object of the present invention is to obtain a charged particle application drawing apparatus such as a focused ion beam drawing apparatus which can prevent accumulation of incident charges on the surface of a sample and can draw a fine pattern with high accuracy. And

[0013]

In the charged particle applied analyzer according to the present invention, plasma is introduced so as to come into contact with the sample surface to be analyzed by irradiation of charged particles, and the incident electric charge is neutralized on the sample surface. It was designed to be transformed.

The charged particle application drawing apparatus according to the present invention is
The plasma is introduced so as to come into contact with the sample surface on which a predetermined pattern is drawn by the irradiation of charged particles, and the incident electric charge is neutralized on the sample surface.

[0015]

In the present invention, since the incident charges are neutralized by the plasma on the sample surface to be analyzed by irradiation of charged particles, the accumulation of the incident charges on the sample surface is avoided, Thereby, the image of the concavo-convex pattern on the sample surface can be displayed clearly.

In the present invention, since the sample surface on which a predetermined pattern is drawn by the irradiation of charged particles is neutralized by the plasma, it is possible to avoid the accumulation of incident charges on the sample surface. A fine pattern can be drawn with high accuracy.

[0017]

【Example】

Example 1. FIG. 1 is a diagram for explaining the configuration of the scanning electron microscope according to the first embodiment of the present invention. In the figure, the same symbols as those in FIG. 4 indicate the same things, and 10a is the SEM of this embodiment. , 31 is a vacuum container for generating plasma 38, 32 is a vacuum pump for exhausting the gas in the vacuum container 31 to bring it into a reduced pressure state, 33 is a gas for introducing the gas to be plasma into the vacuum container 31. An inlet, 37 is an exhaust pipe for guiding the gas in the vacuum container 31 to the vacuum pump 32. Further, 34 is a coil for generating a static magnetic field in a plasma generation region in the vacuum container 31, 35 is an oscillator for supplying microwave power for generating plasma 38, and 36 is plasma 38 in the vacuum chamber 2. And a gas delay pipe for suppressing the inflow of gas into the vacuum container 31.

In this SEM 10a, the degree of vacuum of the vacuum chamber 2 is lower than that of the vacuum chamber 31, and the plasma generated in the vacuum chamber 31 is placed on the mounting table 16 in the vacuum chamber 2. It is introduced so as to come into contact with the surface of the sample 1, and the incident electric charge (electron beam) 3a is neutralized on the surface of the sample.

Next, the operation will be described. First vacuum chamber 2
And the gas in the vacuum container 31 is evacuated by the vacuum pumps 4 and 32 so that the inside of each has a predetermined vacuum degree,
A gas for generating plasma is introduced from the gas inlet 33 at a gas pressure required for plasma generation. And the magnetic field coil 3
When a current is applied to the plasma generator 4, a magnetic field required for electron cyclotron resonance is generated in the plasma generation region, a microwave is generated by the oscillator 35, and the microwave is guided by the waveguide circuit to the vacuum container 31 into which gas is introduced. Plasma 38 is generated in the vacuum container 31 by the electric power of the microwave. Here, the magnetic field generated by the magnetic field coil 34 preferably has a magnetic field distribution in which the trajectory of the electron beam 3a is not affected thereby.

The generated plasma 38 diffuses in the gas delay pipe 36 along the magnetic field and is introduced into the vacuum chamber 2 which is an end station. In this embodiment, the semiconductor substrate 1 which is a silicon wafer, a silicon chip or the like is used. Cover and contact the surface.

In this state, the electron beam 3a is introduced into the vacuum chamber 2 and is incident on the surface of the semiconductor substrate 1 on which, for example, a silicon oxide film having a predetermined pattern is formed, and the conventional SEM 1 is used.
Similarly to 0, the image of the concave-convex pattern on the surface of the semiconductor substrate 1 is displayed on the screen (not shown) of the SEM 10a.

In this state, since the silicon oxide film is an insulator, when no plasma exists in the vicinity of the surface of the substrate, incident charges are accumulated in the surface portion by the incidence of the electron beam 3a, and the electric field due to this charge causes the electric field in the silicon substrate. If it concentrates on the side and its strength increases, the insulating film may be destroyed.

On the other hand, when plasma exists near the surface of the silicon substrate as in the present embodiment, a sufficient number of ions necessary to neutralize the charges incident on the surface of the plasma gather on the surface of the substrate, At the same time, the same number of electrons as those gathered on the substrate surface will be incident on the wall surface of the substrate other than the substrate that is in electrical contact with the part that generates the electron beam and is in contact with the plasma. Plasma neutrality is also maintained. Therefore, it is possible to prevent inconvenience due to charge accumulation such as destruction of the insulating film on the substrate surface.

As described above, in this embodiment, the vacuum container 31 for generating the plasma 38 is provided outside the vacuum chamber 2 in which the sample 1 is placed, and the analysis is performed by irradiation of the electron beam 3a. Since the incident electric charge is neutralized by the plasma 38 on the surface of the substrate, the substrate 1
Accumulation of incident charges on the surface is avoided, which allows the image of the concavo-convex pattern on the surface of the substrate 1 to be displayed clearly.

Example 2. FIG. 2 is a diagram for explaining a focused ion beam drawing apparatus according to a second embodiment of the present invention. In the figure, the same reference numerals as those in FIGS. 1 and 5 indicate the same things, and 20a indicates the present embodiment. In the focused ion beam drawing apparatus of 4a, 4a is emitted from the ion source and
(Refer to FIG. 2), which is an ion beam accelerated by the above and is incident on the semiconductor substrate 1 such as a semiconductor wafer or a semiconductor chip. Here, the substance contained in the plasma 38 generated in the vacuum container 31 is the ion beam 4a. It may be the same substance as the ion.

The focused ion beam drawing apparatus 20
In a, the vacuum degree of the vacuum chamber 2 is lower than that of the vacuum chamber 31 as in the SEM 10a of the first embodiment, and the plasma generated in the vacuum chamber 31 causes the mounting table 16 in the vacuum chamber 2 to move. It is introduced so as to come into contact with the surface of the sample 1 arranged above, and the incident charges (ion beam) 4a are neutralized on the surface of the semiconductor substrate 1.

Next, the function and effect will be described. First above
In the same manner as in the embodiment, the plasma 3 is stored in the vacuum container 31.
8 is generated, and this is along the magnetic field, and the gas delay pipe 36
After being diffused inside, it is introduced into a vacuum chamber 2 which is an end station, and covers the surface of the semiconductor substrate 1 to come into contact therewith.

In this state, the ion beam 4a is moved to the vacuum chamber 2
Then, by scanning with the ion beam 4a, a predetermined pattern is drawn on the insulating film on the surface of the semiconductor substrate 1, for example.

In this state, the scanning of the ion beam 4a is performed on the surface of the insulating film. Therefore, when plasma is not present near the surface of the substrate, the incident charge is accumulated on the surface portion due to the incidence of the ion beam 4a. When the electric field is concentrated on the substrate side and its strength increases, the insulating film may be destroyed.

On the other hand, when plasma exists near the surface of the substrate as in the present embodiment, the number of electrons necessary to neutralize the charges incident on the surface of the plasma gathers on the surface of the substrate, and at the same time, electrons are collected. The same number of ions that have gathered on the substrate surface will be incident on the wall surface other than the substrate that is in electrical contact with the part that generates plasma and is in contact with the plasma,
At the same time as the electrical neutrality of the substrate, the neutrality of the plasma is maintained. Therefore, it is possible to prevent inconvenience due to charge accumulation such as destruction of the insulating film on the substrate surface.

As described above, in the present embodiment, the vacuum container 31 for generating the plasma 38 is provided outside the vacuum chamber 2 in which the semiconductor substrate 1 is arranged, and drawing is performed by irradiation of the ion beam 4a. Since the incident electric charge is neutralized by the plasma 38 on the surface of the substrate 1 to be performed,
Accumulation of incident electric charges on the surface of the substrate 1 is avoided, and thus a fine pattern can be accurately drawn.

In the above embodiment, as the ions incident on the silicon substrate having a silicon oxide film on the surface used in the manufacture of silicon semiconductor circuits, the atoms of group III and group V elements in the chemical periodic table used as dopants are used. There are ions and compound ions such as BF2 ⁺ containing those elements. Alternatively, oxygen ions for forming an oxide film on the surface or inside of the silicon substrate, nitride ions for forming a nitride film, and ions of a compound containing them may be used. Further, it may be silicon ions for disturbing the surface of crystalline silicon. Furthermore, Ar, Xe, H
Noble gas ions of e, Kr, and Ne, Group I, IV of the periodic table
Ions of group elements and ions of compounds containing them are also included.

In the above embodiment, the case where the surface insulator is a silicon oxide film has been shown. However, a photosensitive material such as a silicon nitride film, a silicon oxynitride film, a refractory metal oxide film or a photoresist which is commonly used is used. The same effect can be obtained even with a hydrophilic organic polymer film.

Further, in the above-mentioned embodiment, a plasma source having a pressure larger than that of the charged particle injection region provided with the differential exhaust system is used as the plasma generation source. It is not necessary to provide a differential exhaust system.

Further, in the above embodiment, the plasma was generated by the electron cyclotron resonance method using the static magnetic field, but this method is not always necessary, and RF discharge, DC discharge, photoionization discharge by laser light, etc. It goes without saying that the plasma may be generated by any of the above methods.

Further, in the above-mentioned embodiment, the scanning electron microscope (SEM) and the focused ion beam drawing apparatus are shown as the charged particle application apparatus, but the charged particle application analysis apparatus is the same as the SEM of the first embodiment. The present invention is not limited to this, and may be an apparatus for analyzing the surface using charged particles such as electrons, such as an Auger electron spectroscope, a secondary ion mass spectrometer, and the like. It is needless to say that not only the focused ion beam drawing apparatus described above but also an electron beam drawing apparatus can be used, and the same operation and effect as those of the above-described embodiment can be obtained.

[0037]

As described above, according to the charged particle application analyzer of the present invention, the plasma generating device for generating plasma, which is attached to the outside of the sample chamber in which the sample is placed, is provided. Since the incident charge is neutralized on the sample surface by the plasma generated in the generator, the accumulation of the incident charge on the sample surface is avoided, which allows the image of the uneven pattern on the sample surface to be displayed. It can be displayed clearly.

Further, according to the charged particle application drawing apparatus of the present invention, a plasma generator for generating plasma is provided outside the sample chamber in which the sample is arranged, and is generated in the plasma generator. Since the incident electric charge is neutralized on the sample surface by the plasma, the accumulation of the incident electric charge on the sample surface is avoided, and thus a fine pattern can be drawn with high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a scanning electron microscope (SEM) according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a focused ion beam drawing apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram for explaining a conventional ion implantation device.

FIG. 4 is a diagram for explaining a conventional scanning electron microscope (SEM).

FIG. 5 is a diagram for explaining a conventional focused ion beam drawing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate (sample) 2 Vacuum tank 3a Electron beam 3b Secondary electron 4a Ion beam 10a Scanning electron microscope (SEM) 14 Secondary electron detector 16 Mounting stage 20a Focused ion beam drawing device 31 Vacuum container 32 Vacuum pump 33 Gas Inlet 34 Magnetic field coil 35 Microwave oscillator 36 Gas delay pipe 37 Exhaust pipe 38 Plasma

Claims (2)

[Claims] 1. A charged particle applied analyzer for irradiating a sample placed in a sample chamber with charged particles to analyze the sample, comprising a plasma generator attached to the outside of the sample chamber. The plasma generated in the above is introduced into the sample chamber so as to come into contact with the surface of the sample placed in the sample chamber, and the charged particle beam generated by the main body of the charged particle application analyzer is incident on the sample. Characterized charged particle applied analyzer. 2. A charged particle application drawing device for irradiating a sample placed in a sample chamber with charged particles to draw a predetermined pattern on the sample surface, comprising a plasma generator attached outside the sample chamber. The plasma generated in the plasma generator is introduced into the sample chamber so as to come into contact with the surface of the sample arranged in the sample chamber, and the charged particle beam generated by the main body of the charged particle application drawing device is supplied to the sample. A charged particle application drawing apparatus, which is characterized in that it is incident on a beam.