JPH03176957A - Secondary ion analyzer - Google Patents

Abstract

PURPOSE:To obtain a sufficient neutralizing effect without providing an electron beam generating means in an analyzing means by radiating an electron beam to a sample holder or a secondary electron emitting member to generate secondary electrons during the ion radiation of a sample, and neutralizing the static electricity of the insulating sample. CONSTITUTION:An electron beam E and a secondary ion beam I pass passing holes 11, 12 of an electrode 10 respectively, the secondary ions generated from a sample 3 by the radiation of the beam I pass the electrode 10 and are analyzed by a secondary ion analyzing means. The electron beam E is deflected by a deflecting system incorporated in an electron beam generating means 7 to radiate a secondary electron emitting member 6, a large quantity of secondary electrons are generated by the member 6 and used to neutralize the charged sample 3. For Auger analysis, the electrode 10 is separated from the sample 3, the sample 3 is inclined clockwise, the angle between the normal line on the sample surface and the electron beam E is set to about 75 deg., for example, thus the quantity of secondary electrons is made equal to the quantity of the incident electron beam, and the static electricity on the sample 3 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a secondary ion analyzer suitable for analyzing insulating samples.

[Prior Art] Recently, secondary ions have been developed which have made it possible to analyze the composition of the sample surface by irradiating a sample with -order ions to generate secondary ions, and analyzing these secondary ions with a mass spectrometry system. Analyzers are in practical use. When using this apparatus to analyze an insulating material sample, the sample becomes charged due to ion irradiation, making it impossible to obtain an accurate mass spectrum.

Therefore, in order to prevent such charging, the following method is used.

■ A method in which a means for generating an electron beam for neutralization is prepared and the sample surface is irradiated with a low-speed electron beam from a direction different from that of ion irradiation.

■ A method in which a neutralizing electron beam generation means is built into the secondary ion analysis means, and a low-speed electron beam is irradiated from the same direction as the ion irradiation.

When irradiating electron beams to neutralize charged parts caused by ion irradiation as described above, ideally a sufficient amount of electrons are floating on the sample surface at extremely low speeds. It is necessary to create

[Problems to be Solved by the Invention] In the above method (■), since a certain distance is required between the electron beam generating means and the charged sample surface, the electron beam is in a divergent state, that is, in the vicinity of the charged part. In this case, there are not enough electrons. Furthermore, the efficiency of extracting low-velocity electron beams from an electron source is theoretically poor, and it is difficult to obtain a sufficient amount of electron beams. Therefore, neutralization of charge using this method cannot obtain a sufficient effect.

On the other hand, according to method (2), in order to maximize secondary ion collection efficiency, the electron beam generation means is placed within the secondary ion analysis means placed extremely close to the sample, so the electron beam diverges. Although this method requires less and has a much better effect than the method (2), it has the disadvantage that the configuration is complicated and adjustment is extremely difficult.

Therefore, the present invention has been made in view of this point, and an object of the present invention is to provide an apparatus that can obtain a sufficient neutralizing effect without providing an electron beam generating means inside the secondary ion analysis means. It is something to do.

[Means for Solving the Problems] In order to achieve the above object, the secondary ion analyzer of the present invention irradiates an insulating sample with primary ions generated from an ion source, and collects secondary ions generated from the sample. In the analysis apparatus, a neutralizing electron beam generating means is provided, and during ion irradiation of the sample, the electron beam from the electron beam generating means is irradiated onto the sample holder or a dedicated secondary electron emitting member to generate secondary electrons. is generated, and the generated secondary electrons neutralize the charging of the insulating sample due to ion irradiation.

Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.

[Embodiment] FIG. 1 is a schematic diagram showing the configuration of an example of a secondary ion analyzer according to the present invention, and FIG. 2 is an enlarged view of the main parts for explaining its operation.

In the figure, 1 is a stage placed in a high vacuum, and 2 is a holder placed on this stage, which holds an insulating material sample 3. 4 is the second ion beam ■
5 is a secondary ion analysis means, such as a quadruple plug mass spectrometer, for analyzing secondary ions generated from the sample surface by irradiation with the primary ion beam (1); The analysis means is placed as close as possible to the sample surface in order to efficiently collect the generated secondary ions.

Reference numeral 6 denotes a secondary electron emitting member such as an oxide for generating secondary electrons by electron beam irradiation, and is fixed to the stage 1. The part A of this member that is irradiated with the electron beam is placed as close as possible to the primary ion beam irradiation area on the surface of the sample 3, and at a position that does not interfere with the collection of secondary ions into the secondary ion analysis means 5. Ru. Reference numeral 7 denotes an electron beam generating means for irradiating a narrowly focused electron beam E onto a portion A of this member.

In this configuration, the primary ion beam I is irradiated onto the insulating material sample 3 by the negative ion generating means 4, and at the same time, the electron beam E is generated from the electron beam generating means 7 and is irradiated onto the portion A of the secondary electron emitting member 6. This can prevent the sample from being charged with primary ions. In other words, as shown in FIG. 2, when part A of the secondary electron emitting member 6 is irradiated with a thin electron beam E generated from the electron beam generating means 7, a large amount of secondary electrons E2 generated from the part A are emitted. It floats above the primary ion irradiation area of sample 3.

Therefore, when charging occurs and the potential on the surface of the sample becomes a positive value, electrons are immediately drawn into the 41) type portion, and as a result, the charging is neutralized. Here, the electron beam E is larger in absolute value than the primary ion beam I, and conditions are such that when the secondary electron emitting member 6 is irradiated with this electron beam, it emits the largest number of secondary electrons. It is necessary to set it to . Specifically, regardless of the type of metal, the maximum amount of secondary electron emission is obtained when the electron acceleration voltage is around 5 KV. Furthermore, if necessary, a potential setting means 8 may be provided to apply a potential to the secondary electron emitting member 6 for more efficient neutralization.

FIG. 3 is a schematic diagram showing another example of the secondary ion analyzer according to the present invention, and the same numbers as in FIG. 1 indicate the same components.

This embodiment is characterized by incorporating an Auger electron spectrometer 9 in addition to the secondary ion analyzer.

In the same figure, the electron beam generating means 7 is
and to generate Auger electrons from the sample. Further, the secondary ion generating means 4 is also used for generating secondary ions and etching the sample surface. Furthermore, because the Auger electron spectrometer 9 is installed, the secondary ion analysis means cannot be brought close to the sample surface, so the secondary cone electrode 10 is installed in front to increase the ion attraction efficiency as much as possible. be. Passage holes 11 and 12 for passing the electron beam E and the ion beam E are formed at the tip of the electrode 10, respectively, and are designed to bring the electron beam E and the ion beam E closer to the surface of the sample 3 than the electrode 10.

In such a configuration, the state shown in the figure shows the case where secondary ions are analyzed, and since the electron beam E and the ion beam ■ pass through the passage hole 1112 of the electrode 10, respectively,
-Secondary ions generated from the sample by irradiation with the secondary ion beam (2) pass through the electrode [0] and are analyzed by the secondary ion analysis means. At the same time, the electron beam E is deflected by a deflection system (not shown) built into the electron beam generating means 7 so as to irradiate the secondary electron emitting member 6, so a large amount of secondary electrons are generated from this member. and charged sample 3
used for neutralization. On the other hand, when performing Auger analysis, the electrode 10 is moved away from the sample, the sample 3 is tilted clockwise, and the angle between the normal to the sample surface and the electron beam is set to, for example, about 75 degrees. In this way, the amount of secondary electrons generated from the sample becomes equal to the amount of the incident electron beam, and charging of the sample can be substantially prevented. Then, the electron beam E is irradiated onto the sample 3 without being deflected as shown by the dotted line E' and onto the secondary electron emitting member 6 without u<t a=t, thereby generating Auger electrons from the sample. The generated Auger electrons enter an Auger electron spectrometer 9 and are analyzed. Here, one more electron beam E' and one more ion I from the ion generating means 4 are applied to the sample 3.
Since the surface of the sample is etched by irradiating the two in parallel, it is possible to analyze the elemental composition in the depth direction of the surface of the sample. In this case, when the sample is further etched with ions, it is necessary to irradiate the secondary electron emitting member 6 with a negative electron beam to generate secondary electrons and neutralize the charge on the sample.

It should be noted that the above description is an example of the present invention, and many modifications can be made in implementation. For example, in the above embodiment, the secondary electron emitting member was installed close to the ion irradiation area, but the holder 2 for holding the sample is not limited to this.
All or part of the holder may be made of a material that easily emits secondary electrons, and the holder may be configured to be irradiated with an electron beam.

[Effect] According to the present invention described in detail above, a large amount of secondary electrons can be suspended in the ion-irradiated portion of the insulating material sample, so unlike the conventional method, an electron beam generating means is not provided inside the secondary ion analysis means. It is possible to efficiently neutralize the charge on the sample without providing any.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of the secondary ion analyzer according to the present invention, FIG. 2 is an enlarged view of the main parts to explain its operation, and FIG. 3 is a diagram of the secondary ion analyzer according to the present invention. It is a schematic diagram showing another example. 1: Stage 2: Holder 3: Insulating material sample 4 Primary ion generation means 5: Secondary ion analysis means 6: Secondary electron emitting member 7: Electron beam generation means 8: Potential setting means 9: Auger electron spectrometer E knee Next electron beam ■=-Next ion beam

Claims (1)

[Claims] In an apparatus that irradiates an insulating sample with primary ions generated from an ion source and analyzes secondary ions generated from the sample, a neutralizing electron beam generating means is provided, and the electron beam is generated during ion irradiation of the sample. The electron beam from the generating means is irradiated onto a sample holder or a dedicated secondary electron emitting member to generate secondary electrons, and the generated secondary electrons neutralize the charge on the insulating sample due to ion irradiation. A secondary ion analyzer characterized by comprising: