JPS63313457A - Electron-optical applied device - Google Patents

Abstract

PURPOSE:To aim at both simplification and cost reduction tor the device in the title owing to complete negation of necessity for any cooling device such as water-cooled pipes etc., by composing the coil of each part of an electron lens system, of ceramic insulating wires with high heat resistance. CONSTITUTION:Respective coils 2b and 3b of a condenser lens 2 and an objective 3 and a deflection coil 4 are all composed of special ceramic insulating wires to be easily put in forming process. The method for manufacturing this ceramic insulating wire is carried out in such a way that a forming process such as coil winding is applied to the wire in a step of its unburnt semi-product state where an insulating paint film layer for coating lead wires has not been put in the state of ceramics, but thereafter the paint film layer is burnt at a high temperature to be put in that state. Thus, any cooling system for cooling the coils is no more required at all and the number of turn of a coil can be reduced to increase a current value so that the size of each coil can be reduced because of simplication of the device and enhancement of the maximum allowable current value of each coil.

Description

Detailed Description of the Invention "Field of Industrial Application" This invention relates to various electron optical applied devices such as electron microscopes and ion microanalyzers, and in particular, to heat resistance of coils constituting each part of the electron lens system. This invention relates to an electro-optical application device that aims to improve temperature.

"Conventional technology" For example, TEM (transmission electron microscope), SEM (scanning electron microscope), and FIB (focused ion microscope)
Each part of an electronic lens system such as a beam) device has an electronic lens (condenser lens, objective lens, etc.) with an excitation coil, and a deflection coil (alignment coil, astigmatism correction coil, scanning coil, etc.). It is provided. Conventionally, the coils of each part of this type of electronic lens system have generally been constructed of insulated wires in which conductive wires are coated with a resin-based insulator.

"Problems to be Solved by the Invention" By the way, the heat-resistant temperature of resin-based insulators is usually around 150°C, and at temperatures higher than this heat-resistant temperature, they cannot maintain their insulating properties. However, conventional electro-optical application devices have the following problems.

■Since the coil itself generates heat due to the current flowing through it, especially for condenser lenses and objective lenses that require large currents, a cooling device such as a water cooling pipe is installed, and the coil is heated to the temperature limit of resin-based insulators. It must be cooled to meet the following requirements, which inevitably complicates the equipment.

(2) Due to the reason (2) above, the maximum permissible current value that can be passed through the coil is limited, which necessitates increasing the number of turns in the coil, resulting in an increase in the size of the device.

For example, in a SEM that uses a field emission type cathode, where it is necessary to maintain a high degree of vacuum within the electron lens system, the entire electron lens system is heated (baked) using a heating device. It is necessary to discharge contaminants existing in the system, so-called gas venting, but the temperature of the coil installation area cannot be raised above the heat resistance temperature of the resin-based insulator, so only partial baking can be performed. Can not.

This invention was made in view of the above-mentioned circumstances, and aims to improve the heat resistance temperature of the coils constituting each part of the electronic lens system, thereby improving the maximum allowable current value of the coils, simplifying the device, and achieving high vacuum The object of the present invention is to provide an electro-optical application device that can satisfactorily meet the requirements for optical performance.

"Means for Solving the Problems" The present invention is characterized in that the coils of each part of the electron lens system are constructed of ceramic insulated wires in which conductive wires are coated with ceramic.

"Effect" The heat resistance temperature of the coils that make up each part of the electronic lens system is improved, which eliminates the need for any cooling device to cool the coils, simplifying the equipment, and increasing the maximum allowable current value of each coil. Therefore, it is possible to reduce the number of turns in the coil and increase the current value, making it possible to downsize each coil.Furthermore, it is possible to bake the entire electron lens system uniformly and at high temperature, making it possible to increase the current value by reducing the number of turns in the coil. The degree of vacuum in the lens system can be maintained at a high level.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The figure is a diagram showing a schematic configuration of a SEM to which an embodiment of the present invention is applied.

In this figure, 1 is an electron gun consisting of a filament 1a, Wehnelt ib, and an anode lc, and the electron beam generated by this electron gun 1 is transmitted to a condenser lens 2,
It is focused by an objective lens 3 and deflected by a deflection coil 4 to scan over a sample 5. The secondary electrons emitted from each point on the sample 5 are 2
After being detected by an electron detector 6 and amplified by an amplifier 7, it is supplied to a CRT (cathode ray tube) 8 as a video signal. At this time, the deflection coil 4 and the deflection coil of the CRT 8 are driven synchronously by the same scanning power source 9, thereby displaying an enlarged image of the sample 5 on the CRTB.

Here, the condenser lens 2 and the objective lens 3 have a coil 2b inside a magnetic coil cover 2a, 3a.

3b, its magnetomotive force is concentrated in the center gap, and a lens effect is applied to the electron beam passing through the center.

Next, to explain the main parts of this embodiment, the coils 2b and 3b of the condenser lens 2 and objective lens 3, and the deflection coil 4 are all made of special ceramic insulated wires that are easy to mold (for example, It is composed of Fujithermo (manufactured by Fujikura Electric Cable Co., Ltd.). Regarding the manufacturing method of this ceramic insulated wire, please refer to Japanese Patent Application Laid-Open No. 55-43746.
The detailed explanation will be omitted, but the point is that the insulating coating layer that covers the conductor is still in the unfired, semi-finished stage, and the coil winding process etc. The coating layer is molded and then fired at a high temperature to form a ceramic layer. Before firing, such a special ceramic insulated wire has flexibility equivalent to that of an enameled wire, and after firing, the insulator becomes ceramic and exhibits insulation and heat resistance equivalent to ceramic. Ceramic wires have a heat resistance temperature of 350 to 800°C (heat resistance temperature depends on the material of the conductor, for example, if the conductor is aluminum,
350°C for constantan, 400°C for nickel-plated copper, and 500'C1 gold for silver.

In the case of platinum and platinum-rhodium, the heat resistance temperature is 800°C), which is much higher than the heat resistance temperature of resin-based insulators, which is 150°C. Therefore, a conventionally necessary cooling device such as a water cooling pipe is not required at all, and the configuration of the device is simplified and can be constructed at low cost. On the other hand, since the deflection coil 4, which is not normally water-cooled, has improved heat resistance, it can be baked at 200 to 300°C without worrying about the temperature rise in that part. As a result, it becomes possible to bake the entire electron lens system at a uniform temperature, whereas in the past, only a portion of the electron lens system could be baked, and the degree of vacuum in the electron lens system can be maintained at a high level. Being able to maintain a high degree of vacuum in this way is not only effective when applied to ultra-high resolution SEM and TEM using field emission cathodes, which have been actively developed in recent years.
Analyzers using electron beams or ion beams, such as A
ES (Auger Electron Spectroscopy)
It can be said that it is extremely effective for lowering the detection limit level and increasing sensitivity for IMA (ion micro analyzer) and the like.

"Effects of the Invention" As explained above, according to the present invention, the coils of each part of the electron lens system are constructed of ceramic insulated wires with high heat resistance, so that the following effects can be obtained.

■A cooling device such as a water cooling pipe for cooling the coils of each part of the electronic lens system is completely unnecessary, which simplifies the device and reduces manufacturing costs.

■The heat resistance temperature of the entire electronic lens system has increased, and as a result,
Compared to the conventional method, the entire electron lens system can be baked uniformly and at a high temperature to release gas, and the degree of vacuum in the electron lens system can be maintained at a high level.

■As the heat resistance temperature of each coil in the electronic lens system increases and the maximum allowable current value of each coil increases, it is possible to reduce the number of turns in each coil and increase the current value, which makes each coil smaller. can be realized.

[Brief explanation of drawings]

The figure is a schematic configuration diagram of a scanning electron microscope to which the present invention is applied. 2...Condenser lens, 2b...
Coil, 3...Objective lens, 3b...
Coil, 4...Deflection coil.

Claims (1)

[Claims] An electro-optical application device characterized in that the coils of each part of an electron lens system are constructed of ceramic insulated wires made by covering conductor wires with ceramic.