JP2003157789A - Cathodoluminescence detection device for scanning electron microscope or the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems such as difficulties in image adjustment due to inability of observation of images other than those of cathodoluminescence with a cathodoluminescence detector inserted and nuisances of putting in and taking out the detector for the sake of getting the cathodoluminescence images, with the cathodoluminescence detection device for a scanning electron microscope or the like. SOLUTION: A condensing mirror for detecting a cathodoluminescence image is used also for a bias electrode of a secondary electron detector, low-vacuum secondary electron detection is made possible with the condensing mirror in an inserted state. With this, operability of the device is improved since observation of secondary electron images is easily made with the cathodoluminescence detector in an inserted state, in case of observation of cathodoluminescence images for a scanning electron microscope or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode luminescence detection device such as a scanning electron microscope, and more particularly to improvement of operability.

[0002]

2. Description of the Related Art In order to observe an insulator or the like in a cathodoluminescence image, observation is performed in a low vacuum atmosphere in which the degree of vacuum can be adjusted. I was going there. Since detectors for backscattered electrons and cathode luminescence cannot be inserted at the same time, both detectors have to be taken in and out. In addition, as another method for detecting low-vacuum secondary electrons, Japanese Patent Laid-Open No. 12-126.
As described in Japanese Patent No. 655, a secondary electron image observation in a low vacuum is performed by a combination of a bias electrode and absorption electron detection. However, when the cathodoluminescence detector is inserted, the condenser mirror is arranged so as to cover the sample immediately above, so that the electric field of the bias electrode arranged above the condenser mirror does not reach the sample. Therefore, the amplification action of the generated secondary electrons is not excited and the low-vacuum secondary electron image cannot be observed, so that the low-vacuum secondary electron image cannot be simultaneously observed.

[0003]

In the above prior art, when observing an image, it is troublesome to insert and remove the detector each time the field of view is searched and the cathodoluminescence image observation is switched.

The present invention aims to improve the operability, which is such a problem.

[0005]

In order to solve the above problems, a voltage is applied to the condenser mirror of a cathode luminescence detector, and it is also used as a bias electrode for a secondary electron detector used for observation in a low vacuum. By using the absorption electron amplification amplifier with the cathodoluminescence detector inserted, the secondary electron image can be observed in a low vacuum, and the operation of searching the field of view and observing the cathodoluminescence image can be performed without moving the detector in and out. Easy to do.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic view of an apparatus according to an embodiment of the present invention. In the figure, 1 is an electron gun for generating an electron beam 2, 3 is a converging lens for converging the electron beam, 4 is a deflection coil for scanning the electron beam on the sample 6, and
Reference numeral 5 denotes an objective lens for forming an electron beam on the sample 6, and 7
Is a deflection control circuit for controlling the deflection coil 4, 8 is a lens control circuit for controlling the converging lens 3 and the objective lens 5, and 9 is a lens control circuit.
Is a sample stage for moving the observation field of the sample 6. Secondary electron 1 is emitted from sample 6 by irradiation with electron beam 2.
0, cathode luminescence light 11, etc. are generated, and at the same time, there are absorbed electrons absorbed in the sample.

The detection system includes a secondary electron detector 12 for detecting secondary electrons 10 and an absorption electron amplifier 13 for amplifying absorbed electrons. Further, the cathodoluminescence detector for detecting the light is for taking in and out the condensing mirror 14 for collecting the cathodoluminescence light 11 generated from the sample 6, the optical fiber 15 for transmitting the condensed cathodoluminescence light 11, and the condensing mirror 14. The feed mechanism 18, a spectroscope 19 for separating the detected light, and a cathode luminescence optical signal amplifier 20 for photoelectrically converting and amplifying the separated signal.

The respective detection signals are input to a signal processing circuit 21 for switching and processing the signals, and the lens control circuit 8,
An observation image of each detector is displayed on the observation monitor 23 via the control unit 22 that controls the deflection control circuit 7 and the signal processing circuit 21.

In a scanning electron microscope constructed by such a system, a backscattered electron detector is generally used for observing an image in a conventional low vacuum atmosphere.
Further, recently, as a method for detecting low-vacuum secondary electrons, as described in JP-A-12-126655, a combination of a bias electrode and absorption electron detection,
By combining a bias electrode as described in Japanese Patent Application Laid-Open No. 12-155675 with a backscattered electron detector, secondary electron image observation is performed in a low vacuum. On the other hand, the cathodoluminescence image is often used for observing a sample that emits light such as a phosphor, but recently, a technique of staining a biological sample and observing it in a low vacuum atmosphere has been performed.

In the present invention, the condenser mirror 14 of the cathode luminescence detector is also used as the bias electrode for the secondary electron detector used for observation in a low vacuum, and the condenser mirror 14 is used.
A power source 16 for biasing the secondary electrons 10 and an insulating spacer 17 for insulating the voltage applied to the condenser mirror 14 from the outside are added to the absorption electron amplifier 13
By using, it becomes possible to search the field of view without moving the cathode luminescence detector in and out. FIG. 2 which is an example at the time of low vacuum observation will be described. During low vacuum, gas molecules 24 are present inside the sample chamber. The cathodoluminescence light 11 generated by irradiating the sample 6 with the electron beam 2 is condensed at the position of the optical fiber 15 by the condensing mirror 14, and is transmitted to the spectroscope 19 by the optical fiber 15. At the same time, the secondary electrons 10 generated from the sample are accelerated toward the condenser mirror 14 by the bias voltage applied to the condenser mirror 14. At that time, the gas molecules collide with the gas molecules 24 around the sample, and the gas molecules are divided into + ions 25 and secondary electrons 10. The ionized substances further collide with the gas molecules 24, and the ionization by the secondary electrons 10 proceeds. Since the + ions 25 generated by this gas amplification action flow into the sample 6, the absorption electron amplifier 13 forms a + ion image. Since this + ion image is equivalent to secondary electrons, low vacuum secondary electron image observation is possible.

Further, according to the above-mentioned embodiment, since the cathodoluminescence light 11 and the equivalent secondary electron can be detected at the same time, it becomes possible to display the mixed image of the two signals on the signal processing circuit 21 in real time.
It is possible to obtain an image in which secondary electron information in which the contour of the sample is particularly emphasized is added to the cathodoluminescence image.

[0013]

As a result of the effects of the present invention, the operation of observing an image with a scanning electron microscope or the like is facilitated and the operability is improved.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus according to an embodiment of the present invention.

FIG. 2 is an example during low-vacuum observation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Electron beam, 3 ... Convergence lens, 4 ... Deflection coil, 5 ... Objective lens, 6 ... Sample, 7 ... Deflection coil control circuit, 8 ... Convergence and objective lens control circuit, 9
... sample stage, 10 ... secondary electron, 11 ... cathodoluminescence light, 12 ... secondary electron detector, 13 ... absorption electron operational amplifier, 14 ... focusing mirror, 15 ... optical fiber,
16 ... Bias power supply, 17 ... Insulating spacer, 18 ... Feed mechanism, 19 ... Spectrometer, 20 ... Cathode luminescence optical signal amplifier, 21 ... Signal processing circuit, 22 ... Control unit, 23 ... Observation monitor, 24 ... Gas molecule, 25 ... + ion.

Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI theme code (reference) H01J 37/28 H01J 37/28 B (72) Inventor Shigeru Kawamata 1040 Ichige, Itamo, Hitachinaka City, Ibaraki Prefecture Hitachi Science Co., Ltd. F-term in Systems (reference) 2G001 AA03 BA07 CA03 CA07 DA06 GA01 GA06 GA09 HA09 HA13 JA07 JA12 2G043 AA01 CA05 EA11 FA01 FA02 GA07 GB11 HA03 LA01 5C033 NN01 NN10 NP01 NP02 RR03 RR04 RR06 RR10 UU04 UU06

Claims (4)

[Claims] 1. A means for irradiating a sample with a converged electron beam, applying a voltage to a condenser mirror of a cathode luminescence detector for detecting light generated therefrom, and generating an electric field for the sample. A cathode luminescence detection device such as a scanning electron microscope. 2. A scanning method comprising means for applying a voltage to a condenser mirror of a cathodoluminescence detector, wherein the bias electrode of the detector utilizes a secondary electron amplification effect in a low vacuum atmosphere. Cathode luminescence detection device such as electron microscope. 3. A scanning electron microscope or the like according to claim 2, wherein the detector utilizing the secondary electron amplifying action in the low vacuum atmosphere uses the sample absorption current as image information. Cathode luminescence detector. 4. A cathodoluminescence detection device for a scanning electron microscope or the like, characterized in that the cathodoluminescence detection signal according to claim 1 and a detection signal from a detector utilizing a secondary electron amplification effect are combined and displayed as an image. .