JPS5966031A - High brightness surface ionization type ion source and its manufacturing method - Google Patents

Abstract

PURPOSE:To reduce the emission area of ion source substance thus to improve ion emission per unit area by covering the surface of ion generating section composed of porous W except the central portion with an ion inpermeable film having high melting point such as W. CONSTITUTION:A porous W5 cut into a conical shape is electron beam welded onto the tubular member 6 of Ta to form a conical ion generating section the surface of which is spattered with W7. Thereafter the leading edge is cut to have the diameter of 0.3-0.5mm. phi to remove collapsed portion from the cutting face through electrolytic grinding. Since the evaporated ion source substance will emit only through said cutting face 8 having small diameter, ion beam of high brightness can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high brightness surface ionization type ion source and a method for manufacturing the same.

Secondary ion mass spectrometry (SIM) is a method that measures the elemental distribution and state of the sample surface by analyzing the secondary ions emitted from the sample surface when the sample surface is irradiated with a primary ion beam.
The ion microprobe mass spectrometer (IMMA) is known as an example of a device used for S. used to do. And-
By improving the secondary ion current and reducing the size of the beam spot, we can increase the spatial resolution, that is, the ability to detect elements in a sample, and the detection limit. It is hoped that it will be possible to analyze the spatial distribution of extremely small amounts of impurities in IC chips, etc. Therefore, the analysis of trace elements requires a high-vacuum device as well as an ion source with high current and density. .

IMMA and HVCitl are used to perform local analysis of the sample surface by using probe ions as a narrow beam using a laser beam.
A small value (e.g. invitation Iltm96)
), generally 31
- Raw 1. By passing the ion beam through a focusing system, a minute amount of radiation is generated.
It is conceivable to change the I Cerato dimensions to A:, but the current value reaching the sample surface will be smaller, and the surface analysis will be difficult.7
V(ij will be disadvantageous.1・(The beam current value (thick value) that reaches ff+'+ is Ipmax = 'rπ2-B-d'8/ 16 Cs
``'', where B is the brightness, d is the size of the spot, and CFI is the spherical aberration coefficient. Therefore, it can be seen that the beef 2 current value (c) is proportional to the brightness of the ion source. ).

From the above viewpoints and points, in the analysis of this VC, the test *
In order to form a primary ion beam spot as small as possible and as strong as possible on the surface, it is necessary to make the brightness of the ion source as high as possible, and a high brightness ion source is required. However, in the conventionally proposed surface ↑Ff, I'lfl type ion source, the first
As shown in the figure, the limit for the effective diameter of the porous tungsten 1 that constitutes the ion generating part is 2 culms from the viewpoint of processing, and it is practically impossible to make it smaller than that.
``It's difficult 611. In FIG. 1, 2 represents a cathode, 3 represents a heater, and 4 represents an electrical connection. Ion species vapor is also generated from the surrounding fi+- of Zeporus tungsten.If you try to extract a beam of high brightness, you will emit wasted ion species, resulting in contamination of the ion source and (f.

This results in a wide range of problems, such as a mechanical P edge defect (14^ where ions 11+1 are metal), etc.

Therefore, it is an object of the present invention to provide a high brightness surface electron hlE2X'J ion source by reducing the emission surface (11) of the ion 1-111 substance to improve the ion emission per unit area. is the white of the eye.

Therefore, in the ion source according to the invention, the surface of the ion source made of porous tungsten is coated with an ion-impermeable film having a high melting point, such as tungsten, except for the central part. Preferably, the ion generating section has a conical shape, and is constructed so that the ion generating portion is emitted only from its tip.

Another purpose of the octopus emitted] is -fr:, the simple +1 of the F ion source! The object of the present invention is to provide a manufacturing method.

That is, the manufacturing method of the present invention is characterized in that the ion generating part made of porous tungsten is sputter-deposited, except for the central part, with a substance that has a high melting point of tungsten and does not bend the ions (2J'G). There is.

Another JP of this invention, '? According to the characteristics, the ion generating part of the ion source made of tungsten is formed into a 3F conical shape, and the ion generating part of the ion source is made of tungsten having a high melting point [, Doesn't it generate ionic vapor? 7+'(?
i and y! c5I! lf, and Z to cut the tip j'41 of the circular 1o-shaped ion generating part.

According to the manufacturing method of this invention, conventional-C
&1 effective diameter 2tnTAt73culm11') - was the limit [], but it is now possible to easily obtain an ion source with ion emission [] of 5 to r1.5 nrrxl i or less. Moreover, the ion source according to the present invention not only can reduce the size of the -order ion beam spot, but also allows the ion vapor generated in the ion generation section to be distributed in the center 1 (1) without being diffused to the surroundings. Since the ions are emitted only from the ion emitting port of 1, the ion emitted per unit surface viscosity (14i), that is, the brightness can be significantly improved.In other words, when obtaining a small primary ion beam spot, the beam force and current of the spot of the same diameter is 16 to 50. This invention can be doubled, making highly sensitive analysis possible. Also, since the generated ions can be emitted effectively as a narrow ion beam, contamination of the system by extra ions can be avoided. This will be explained with reference to the figures.

2 to 4 show 11 examples of the manufacturing method of the present invention, and FIG. 2 shows a process of electron beam welding a porous tungsten 5 cut into a circular ψIL shape to a tantalum tubular body 6. . As shown in FIG. 3, tungsten 7 is vapor-deposited onto the surface of the conical ion generating portion thus formed to a thickness of 10/Im'IA. After that, as shown in Fig. 4,
and its diameter is [], 3-0.5 mm%. For example, the cut surface 81tJ is polished by polishing V to remove the Ir41 portion that has crushed the hole. Therefore, the evaporated material of the ion species is generated by an ion beam with a high ZIlt degree of 7'C which is emitted only from this small diameter (: rf+i 8).

FIG. 5 shows another embodiment, in which tungsten 11 is deposited in strips on the surface of conventional porous tungsten 9, leaving a central portion 10.

&J ion generation 131s failure 1゛f in each of the above implementations e11
I have posted about tungsten as a moon and jc- is 1
．． +I Normal 12 OF1 - At a temperature of about 1,300°C, it is also emitted (1:' Any conductive material that can cut off the steam. Example 11: J,' PAo,
Ta A! '1' can be used.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing a conventional ion IllI river.
2 to 4 are cross-sectional views showing the manufacturing process of one embodiment of the ion source of the present invention, and FIG. 5 is a cross-sectional view showing another embodiment of the present invention. In the figure, 5, 9: ion generation part, 7.11: tungsten coating. Figure 1 Figure 2 Figure 3 Circle Figure 4 Figure 5 Procedural amendment (spontaneous) October 29, 1980 Dear Commissioner of the Patent Office ■, Indication of the case 1982 Patent Application No. 175390 Process for its production 3, Relationship with the person making the amendment (Part 3): Applicant Address: 2500 Hagizono, Chigasaki City, Kanagawa Prefecture Name: Japan Vacuum Technology Co., Ltd. 4, Agent 5, Grasp the detailed description of the invention in the specification to be amended 6. Details of the correction The word ``cando'' in line 6 of page 4 will be corrected to read ``1 ion generator.''

Claims (1)

[Claims] 1. The surface of the ion generating part made of tungsten, except for the central part, is coated with an ion-impermeable material having a high melting point, such as tungsten, so that ions 111j! ll The snow quality release area has been reduced! High brightness surface electron 1illi type ion source with 1 loaf. 2. Made of horus tungsten 2) An ion-impermeable substance with a high melting point such as tungsten is deposited on the surface of the ion generating portion except for the central portion thereof using a snow setter. The method for producing ions described in Nihii J is to form an ion generating part made of type 5R-rustungsten into a conical shape, depositing an ion-impermeable substance with a high melting point such as tungsten on its surface, and 2. The method of manufacturing an ion source according to claim 1, further comprising cutting the tip of the conical ion generating section to form an ion species discharge port.