JPH0363175B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron microscope equipped with an electron beam energy analyzer used in Auger electron analysis and the like.

[Prior art] Conventional Auger electron analyzers, such as cylindrical mirror energy analyzers (CMA), use the deflection effect of an electric field to deflect secondary electron beams from a sample, depending on their energy. Most of the energy analyzers use a type of energy analyzer that spatially separates electrons, or, for example, create a magnetic field between two magnetic pole plates and use the difference in deflection force caused by this magnetic field to separate the energy of electrons. It is. The trajectory of the secondary electron beam in these types of energy analyzers is easily affected by disturbance magnetic fields or electric fields, so in recent electron microscopes in which the sample is placed in the objective lens magnetic field and the electron beam is irradiated, the energy of the CMA, etc. It is not possible to incorporate an analyzer to perform energy analysis of Auger electrons, etc.

[Object of the invention] The present invention provides an electron microscope in which a sample is placed in a magnetic field and irradiated with an electron beam.
Energy analysis of Augier electrons, etc. in the electron beam
The purpose is to provide a device that can perform analysis without using CMA.

[Structure of the Invention] Therefore, the present invention includes an electron gun, a sample placed in a lens magnetic field, a first stage electrostatic lens 4 disposed between the electron gun and the sample, and the electron gun. and the second stage electrostatic lens 5 disposed between the sample and the sample.
, an electron detection means arranged between both electrostatic lenses 4 and 5, a voltage of -(E+ΔE) is applied to the first stage electrostatic lens, and a voltage of -(E+ΔE) is applied to the second stage electrostatic lens, where E is the sweep voltage. a sweep power supply for applying a voltage of -E to the electrostatic lens; an electron detection means disposed between the two electrostatic lenses for capturing and detecting electrons staying between the two electrostatic lenses; and the electron gun. and a correction magnetic field type lens 6 disposed between the electrostatic lens 6 and the sample, and a correction magnetic field type lens 6 disposed between the electrostatic lens 6 and the sample, and a correction magnetic field type lens 6 disposed between the electrostatic lens 6 and the sample, and a correction magnetic field type lens 6 arranged between the electrostatic lens 6 and the sample. The present invention is characterized in that it includes a control circuit for supplying an excitation current to the magnetic field type lens in accordance with the voltage sweep.

[Example] The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention. In the figure, 1 is an electron gun, and 2 is, for example
This is an incident electron beam accelerated to 100KV to 200KV.
3 is a focusing lens that optimally reduces the probe diameter of the incident electron beam 2. 4 and 5 indicate electrostatic lenses for energy analysis which are the main parts of the present invention, and 4 and 5 respectively indicate electrostatic lenses for energy analysis, which are the main parts of the present invention.
It consists of a set of three ring-shaped electrodes, a, 4b, 4c and 5a, 5b, 5c, arranged symmetrically about the optical axis. Here, the electrodes 4a and 4c are connected to a power source.
A voltage of -(E+ΔE) (KV) is applied from P ₁ , and the electrode 4b is maintained at the ground potential. or,
A voltage of -E (KV) is also applied to the electrodes 5a and 5c from the power source _P2 , and the electrode 5b is maintained at the ground potential. 6 is a magnetic field type probe correction lens for preventing the probe diameter of the incident electron beam 2 from changing on the sample surface when the lens action of the electrostatic lenses 4 and 5 is changed; A potential of -E is applied to the correction lens so as not to greatly disturb the electric field generated by the electrostatic lenses 4 and 5.
Reference numeral 7 denotes an electron beam detector provided between the electrostatic lenses 4 and 5. Electrons with low energy are detected by the electron beam detector 7, and the detected intensity is displayed on a display device, etc. (not shown). Ru. 8 is a sample placed in the magnetic field of the objective lens 9, and 10 is a secondary electron beam emitted from the sample surface when the sample 8 is irradiated with the incident electron beam 2. Note that 11 is a power source for the correction lens, and the power source 11 is a control circuit 12.
controlled by.

In the device configured as described above, the electron gun 1
For example, the incident electron beam 2 emitted from 100
(KV) and focused by the focusing lens 3. The incident electron beam 2 passing through the focusing lens 3 is -
The negative potential of (E+△E)(KV) is decelerated to 100-(E+△E)(KV) by the electrode 4a, but since the electrode 4b is held at the ground potential, the electrode It is accelerated between 4a and 4b and passes through electrode 4b at 100 (KV). Here, the incident electron beam 2 passing through the electrode 4b at 100 (KV) is -
It is decelerated again to 100-(E+ΔE)(KV) by the electrode 4c to which a negative potential of (E+ΔE)(KV) is applied, and passes through the electrode 4c toward the electrostatic lens 5. By the way, since the electrostatic lens 4 and the electrostatic lens 5 have a lens effect, when the lens effect is changed, the probe diameter of the incident electron beam 2 on the sample 8 may change. Therefore, in this embodiment, a correction lens 6 having a lens main surface that coincides with the main surface of the composite lens formed by the electrostatic lens 4 and the electrostatic lens 5 is provided, and the electrostatic lens 4 and the electrostatic lens 5 It has a function to cancel the change by interlocking the variable operation of the lens action. That is, the control circuit 12 of the power supply 11 is supplied with signals corresponding to the voltages applied to the electrostatic lenses 4 and 5 from the power supplies P ₁ and P ₂ , and the control circuit 12 receives signals according to the voltages applied to the electrostatic lenses 4 and 5. An excitation current is supplied to the correction lens. On the other hand, the electrode 4c is 100-(E+△E)(KV)
The incident electron beam 2 that has passed through is accelerated to 100-E (KV) by the electrode 5a given a potential of -E (KV), and further accelerated to 100-E (KV) by the electrode 5b given a ground potential. accelerated until. But −E(KV)
Also, by the electrode 5c given a potential of 100-
Although the electron beam 2 is decelerated to E (KV), since the sample 8 is at ground potential, the incident electron beam 2 ultimately enters the sample 8 at 100 (KV). When the sample is irradiated with the incident electron beam 2 in this way, a secondary electron beam 10 is emitted from the surface of the sample 8, and this secondary electron beam 10 contains electrons ^{e -} having various energy values. exists. Therefore, as shown in Figure 2, some of the electrons e ^- emitted from the sample 8 are electrons e ^- with energy less than E.
is reflected by the electrode 5c to which the −E potential is applied and cannot pass through. Further, electrons e ^- having a certain energy -E (keV) or more passing through the electrode 5c are accelerated at the electrode 5b to which the ground potential is applied. When it is decelerated by the electrode 5a and released from the sample, it heads toward the electrostatic lens 4 from the electrode 5c while retaining energy. At this time, the electrons e ^- which are about to be diverged by the correction lens 6 are focused toward the center of the electrostatic lens 4 . Among the electrons e - that have passed through the correction lens 6 and reached the vicinity of the lower surface of the outer electrode 4c ^of the electrostatic lens 4, the potential of the electrode 4c -
Electrons with energy greater than (E+ΔE)(KV) pass through the electrostatic lens 4, but electrons e ^- with energy smaller than that are reflected and cannot pass through. As a result, electrons e ^- whose energy is in the range of E (keV) to E+ΔE (keV) when radiated from the sample are stagnated between the electrode 4c and the correction lens 6. The electrons e ^- stagnated in this manner are deflected toward the electron beam detector 7 by an extremely weak collection electric field formed in front of the electron beam detector 7 and detected. Therefore, by sweepingly varying this E and recording changes in the output of the electron beam detector 7, the energy spectrum of the electrons e ^- emitted from the sample 8 can be obtained.

[Effects] As described above, according to the present invention, even when a sample is placed in a magnetic field, energy analysis of Auger electrons, secondary electrons, etc. emitted from the sample can be performed without being affected by this magnetic field. be able to.

Furthermore, the electron microscope based on the present invention includes a correction magnetic field type lens 6 disposed between the electron gun and the sample.
In addition, in order to correct the change in the diameter of the electron beam that passes through both the electrostatic lenses and irradiates the sample with the sweep of the voltage -E, the magnetic field type lens is provided with a magnetic field type lens that responds to the sweep of the voltage -E. Since it is equipped with a control circuit for supplying an excitation current, it is possible to maintain the analysis region of the sample within a predetermined region when performing the energy analysis of Auger electrons and secondary electrons described above.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining the present invention. 1: Electron gun, 2: Incident electron beam, 3: Focusing lens, 4, 5: Electrostatic lens, 6: Correction lens,
7: Electron beam detector, 8: Sample, 9: Objective lens,
10: Secondary electron beam, 11: Power supply for correction lens, 1
2: Control circuit.

Claims (1)

[Claims] 1. An electron gun, a sample placed in a lens magnetic field,
a first-stage electrostatic lens 4 disposed between the electron gun and the sample; a second-stage electrostatic lens 5 disposed between the electron gun and the sample; and both electrostatic lenses. The electron detection means arranged between 4 and 5 and the electrostatic lens of the first stage when E is the sweep voltage -(E+
A sweep power source for applying a voltage of △E) and a voltage of -E to the second stage electrostatic lens, and a sweep power source for capturing electrons that are placed between both electrostatic lenses and staying between both electrostatic lenses. An electron detection means for detecting electrons, a correction magnetic field type lens 6 disposed between the electron gun and the sample, and electrons that pass through both the electrostatic lenses and irradiate the sample as the voltage is swept. 1. An electron microscope equipped with an electron beam energy analyzer, characterized in that the electron microscope is equipped with a control circuit for supplying an excitation current to the magnetic field type lens in accordance with the sweep of the voltage in order to correct changes in the diameter of the wire. 2. Each of the electrostatic lenses 5, 4 is composed of three ring-shaped electrodes, the center electrode of each electrostatic lens is at ground potential, and a desired voltage is applied to the outer electrode of each electrostatic lens. An electron microscope comprising the electron beam energy analyzer according to claim 1.