JPH03176649A - Auger electron spectroscopic device - Google Patents

Abstract

PURPOSE:To prevent the influence of electrification by irradiation with ions by irradiating a sample holder with an electron beam and generating the secon dary electron beam to neutralize the electrification of an insulating sample at the time of etching by the irradiation with the ions. CONSTITUTION:The electron beam E1 generated from an electron beam project ing system 5 is projected to the position to be analyzed on the insulating sample 3 by the control of a computer 14 and the generated auger electrons are ana lyzed by an auger electron spectroscopic system 11 and, therefore, the analysis of the extreme surface of the sample is executed. The electron beam E2 generat ed from the electron beam projecting system 5 projects a secondary electron releasing member 4 fixed to the insulating edge part on a sample holder 2. Since ions I are generated from an ion generating means 12 and project the surface of the sample 3, the sample surface is etched. A large quantity of the secondary electrons are released from the member 4 by the irradiation with the electron beam E2 at the time of this etching and, therefore, the electrification of the sample 3 by the ions is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an Auger electron spectrometer suitable for analyzing insulating samples.

[Prior Art] In Auger electron spectroscopy, an ion etching device is often used in combination to analyze the elemental composition in the depth direction of a sample, so-called depth profile analysis. In normal depth profile analysis, electron beam irradiation and ion irradiation are performed alternately. During electron beam irradiation, the composition is analyzed using Auger electron spectroscopy, and while ion irradiation is performed, ion etching is performed. The action is used to gradually scrape away the sample from the surface. When analyzing an insulator, it is necessary to take measures to prevent the sample from being charged (charge-up) due to electron beam irradiation or ion irradiation.

In the commonly used antistatic method, the angle of incidence of the electron beam on the sample (the angle between the normal to the sample surface and the electron beam) is set to a large value, for example about 75 degrees, and the secondary electrons generated from the sample are By making the amount of electron beam equal to that of the incident electron beam, charging of the sample is substantially eliminated.

[Problems to be Solved by the Invention] However, although such methods can prevent ii) electrification caused by electron beam irradiation, no measures have been taken to prevent electrification caused by ion irradiation. Therefore, if electron beam irradiation is restarted immediately after ion irradiation, the ion beam irradiation may cause distortion or deviation of the Theoges vector due to charging, which may make it difficult to perform normal analysis.

Therefore, the present invention has been made in view of these points, and provides an Auger electron spectrometer that can prevent normal depth profile measurement of a sample caused by ion irradiation. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the Auger electron spectrometer of the present invention alternately irradiates an insulating sample with an electron beam and ions,
In an apparatus that analyzes the sample in the depth direction by repeating Auger electron spectroscopy and etching of the sample surface, when etching by ion irradiation, the electron beam is applied to a sample holder that holds the sample or a special The present invention is characterized in that the secondary electron emitting member is irradiated to generate secondary electrons, 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.

[Example] The accompanying drawing is a schematic diagram showing an example of the configuration of an Auger electron spectrometer according to the present invention.

In the figure, 1 is a stage placed in a high vacuum atmosphere, 2 is a sample holder placed on this stage, and holds an insulating material sample 3. Reference numeral 4 denotes a secondary electron emitting member fixed to the edge of the sample on the holder 2, and this member is made of, for example, an oxide that easily generates secondary electrons when irradiated with an electron beam.

Reference numeral 5 denotes an electron beam irradiation system for irradiating the sample 3 and the secondary electron emitting member 4 with an electron beam, which includes an electron gun 6 and a focusing lens 7.
It is composed of. 8 is an electron beam irradiation control circuit that sets irradiation conditions such as acceleration voltage and beam current by controlling the electron gun 5 and focusing lens 7; A channel B is provided for setting the irradiation conditions for the electron generating member 4. 9 is a deflection system built into the electron beam irradiation system 5; 10 is a deflection control circuit for controlling this deflection system; this control circuit also has a channel for setting the amount of deflection for scanning over the sample 3; A and a channel B for setting the amount of deflection for irradiating the secondary electron emitting member 4.

11 is an Auger electron spectroscopy system for analyzing Auger electrons generated from the sample 3 by electron beam irradiation. 12
Reference numeral 13 indicates an ion generation means for irradiating the surface of the sample 3 with an ion beam to perform etching, and 13 an ion irradiation control circuit for setting the ion irradiation conditions.

14 is the electron beam irradiation control circuit 8. This is a computer that controls the deflection control circuit 10 and the ion irradiation control circuit 13, respectively.

The operation in this configuration will be explained in detail below.

First, the stage 1 is tilted, and the tilt angle of the sample 3 is set to an angle (for example, about 75 degrees) at which the sample to be measured will not be charged even if it is irradiated with an electron beam. In addition, the electron beam irradiation conditions (acceleration voltage, beam current, etc.) corresponding to the content to be analyzed are set in channel A of the electron beam irradiation control circuit 8, and the electron beam is applied to the secondary electron emitting member 4 in channel B. Irradiation conditions (for example, the acceleration voltage is usually 5K for any metal) under which the maximum amount of secondary electrons is emitted from this material when irradiated.
It is sufficient to apply a voltage of about v).

At this time, the amount of beam current is determined by the ion generating means 12, which will be described later.
The absolute value is set to be approximately equal to or greater than the absolute value of the ion current amount from. Furthermore, the deflection control circuit 10 is operated to cause the electron beam to two-dimensionally scan the sample surface, and the analysis position is determined while displaying the sample image using a secondary electron scanning image observation device (not shown). The deflection amount for irradiating the analysis position with the electron beam is set in channel A of this deflection control circuit, and the deflection amount for irradiating the secondary electron emitting member 4 with the electron beam is set in channel B. Furthermore, etching conditions are set in the ion irradiation control circuit 13.
In other words, the ion current amount and irradiation time are set.

Then, when an analysis start switch (not shown) is turned on, the computer 14 controls the electron gun control circuit 8 and the deflection control circuit 1.
A signal for reading out the contents set in each channel is supplied to each channel. As a result, the electron beam generated from the electron beam irradiation system 5 is irradiated to the position to be analyzed on the sample 3 as shown by the solid line E1 in the figure, and the generated Auger electrons are analyzed by the Auger electron spectroscopy system 11. Analysis, that is, analysis of the outermost surface of the sample is performed.

Next, the computer 14 controls the electron beam irradiation control circuit 8 and -
A signal is supplied to the amount control circuit 10 for reading out the contents set in each channel B, and at the same time, a signal is also supplied to the ion irradiation control circuit 13. As a result, the electron beam generated from the electron irradiation system 5 irradiates the secondary electron emitting member 4 as shown by the dotted line E2 in the figure. In addition, the ion generating means 1
Since ions I are generated from the sample 2 and irradiated onto the sample 3, the sample surface is etched. During this etching, since a large amount of secondary electrons are emitted from the secondary electron emitting member 4 by the electron beam E2 irradiation, it is possible to prevent the sample from being charged with ions. In other words, the secondary electrons emitted from the secondary electron emitting member float above the ion-irradiated area of the sample, so when charging occurs due to ion irradiation and the potential on the sample surface becomes a positive value, the electrons immediately It is drawn into the charged part, and as a result, the charge is neutralized.

Then, when the desired etching is completed, the computer 14 uses the ion j! At the same time as stopping the signal to the a-irradiation control circuit 13, the contents of each channel A of the electron beam irradiation control circuit 8 and the deflection control circuit 10 are read out again, and the analysis position on the sample 3 is irradiated with the electron beam. Perform analysis. Thereafter, ions are generated from the ion generating means to etch the surface of the sample 3, and at the same time, the secondary electron emitting member 4
The charge on the sample caused by ion irradiation is neutralized by irradiating it with an electron beam. Thereafter, the above-described operations are repeated to perform depth profile analysis of the insulating material sample.

It should be noted that the above description is an example of the present invention, and many modifications can be made in implementing the present invention. For example, although the above embodiment shows the case where the secondary electron emitting member is fixed to the sample holder, the secondary electron emitting member may be fixed to the stage without being limited to this, or it may be fixed to the tip of a movable rod that can be operated from the outside. It may be fixed.

In addition, in the above embodiment, the computer specifies each channel of the electron beam irradiation control circuit and the deflection control circuit, but the computer can directly specify each mold beam irradiation condition, electron beam deflection amount, ion type condition, etc. A system may also be used in which the electron gun, focusing lens, deflection system, and ion generating means are controlled by inputting the information from the computer.

[Effects] According to the present invention detailed above, when performing depth profile analysis of an insulating material sample using an Auger electron spectroscopy system,
Since secondary electrons can be made to float on the surface of the sample at the same time as the ion etching, the electrical charge caused by ion irradiation can be neutralized.

As a result, the influence of charging due to ion irradiation can be prevented, so that normal depth profile analysis can be performed.

[Brief explanation of drawings]

The accompanying drawing is a schematic diagram showing an example of the structure of an Auger electron spectrometer according to the present invention. 1: Stage 2: Sample holder 3 2. Insulating physical sample 4: Secondary electron emitting member 5: Electron beam irradiation system 6: Electron gun 7: Focusing lens 8: Electron beam irradiation control circuit 9: Deflection system 10: Deflection control circuit 11 : Auger electron spectrometer 12 : ion generation means 13 : ion irradiation control circuit 14 : computer

Claims (1)

[Claims] In an apparatus that performs analysis in the depth direction of a sample by alternately irradiating an insulating sample with an electron beam and ions and repeating Auger electron spectroscopy and etching of the sample surface, during etching by ion irradiation, The electron beam is irradiated onto a sample holder holding the sample 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. An Auger electron spectrometer characterized in that it is configured to