JPH0428155A - Measuring of beam diameter of focusing charged particle beam - Google Patents

Abstract

PURPOSE:To enable an accurate measurement of a beam diameter by scanning a focused charged particle beam in a perpendicular direction to a linear part of a shield, while scanning in a parallel direction at higher rate. CONSTITUTION:An ion beam is focused on a knife-edge 20 with a focusing lens 12, and an X-direction scanning signal is given to an X-direction deflector 13 via a DA converter 15 and an amplifier 14 from a CPU 19, and similarly a Y-direction scanning signal is given to a Y-direction deflecting system 16 via a DA converter 18 and an amplifier 17 from the CPU 19, and thus a focused ion beam is scanned in Y direction, while vibrating on a edge 20 in Y direction at an extremely high rate. With such a scanning, the ion beam passed through an edge 4 is entrapped in a Faraday cup collector 21, and a signal is obtained with the CPU 19 via an amplifier 22 and an AD converter 23. The CPU 19 measures a beam diameter from a scanning time interval tQ calculated from I90 which corresponds to 90% of the maximum beam current and I10 corresponding to 10%.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for accurately measuring the diameter of a focused charged particle beam.

(Prior art) Electron beam devices such as scanning electron microscopes and electron beam lithography devices use electron beams, and ion beam devices such as ion implantation devices and ion beam lithography devices use ion beams. However, in any device, the diameter of the electron beam or ion beam must be adjusted accurately.

A conventional beam diameter measuring method will be explained using an apparatus using an electron beam as shown in FIG. In the figure, reference numeral 1 denotes an electron gun, and the electron beam emitted from the electron gun 1 is focused onto a knife 4 by a focusing lens 2.
When a linear scanning signal is applied to the deflector 3 from the DA converter 6 and the amplifier 5, the focused electron beam scans the straight part of the knife 4 at right angles. Due to this scanning, the electron beam passing through the knife 4 is collected by the Faraday cup 8, and a beam current based on the electron beam is obtained by the CPU 7 via the amplifier 9 and the AD converter 10. The amount of change in beam current with respect to scanning time is as shown in FIG. 3, for example, when the electron beam is scanned from left to right. The CPU 7 calculates a scanning time tQ between 190, which corresponds to 90% of the maximum value of the beam current, and 110, which corresponds to 10%.
Measure the diameter of the beam from In reality, at the same time as such scanning, a counter (not shown) is counting clocks from a clock oscillator (not shown), and the CPU 7
The beam diameter is measured based on the count value of a counter (not shown) during the scanning time tQ.

As another method for measuring the beam diameter, a secondary electron detector is placed between the deflector 3 and the knife 4, and the beam is scanned over the knife 4 in the same manner as described above. A secondary electron detector detects secondary electrons generated from the
There is also a method of measuring the beam diameter.

Such a beam diameter measuring method is also applied to measuring the diameter of an ion beam.

(Problem to be Solved by the Invention) However, when scanning a knife with an electron beam, if the scanning is not very fast, the thin part at the tip of the knife is etched, making it impossible to accurately measure the beam diameter. Also, since ions have a much larger mass than electrons,
This effect is significant.

Such a problem also occurs when a metal wire is used as a shield having a straight portion.

In order to solve such problems, it is possible to increase the scanning speed extremely, but due to the limit of the response speed of the hardware system between the Faraday cup 8 or the secondary electron detector (not shown) and the CPU, it is difficult to increase the scanning speed. There are limits to increasing speed.

The present invention is aimed at solving such problems.

(Means for Solving the Problems) For this purpose, the method for measuring the diameter of a focused charged particle beam of the present invention involves scanning a focused charged particle beam over a shielding body having a straight portion, and obtaining beam information obtained by the scanning. In a focused charged particle beam diameter measurement method that measures the beam diameter based on a signal, the focused charged particle beam is scanned at high speed in a direction parallel to a straight line part of the shield while scanning a beam perpendicular to the straight line part. I made it scan in the direction.

(Embodiment) FIG. 1 is a schematic diagram of an ion beam diameter measuring device showing an embodiment of the present invention. In FIG. 1, 11 is an ion gun, 12 is a focusing lens, 13 is an X-direction deflector, 14 is an amplifier, 15 is a DA converter, 16 is a Y-direction deflector, and 17
is an amplifier, 18 is a DA converter, 19 is a CPU, 20 is a knife blade, 21 is a Faraday cup, 22 is an amplifier, and 23 is an AD converter.

In such an apparatus, an ion beam ejected from an ion gun 11 is focused into a knife lens 2 by a focusing lens 12.
0, and is transmitted from the CPU 19 to the X-direction deflector 13 via the DA converter 15 and the amplifier 14 as shown in FIG.
An X-direction scanning signal as shown in a) is applied to the Y-direction deflector 16, and an X-direction scanning signal as shown in FIG. When a Y-direction scanning signal with an extremely high frequency is applied, the focused ion beam moves over the knife blade 20 in the Y direction (i.e., in a direction parallel to the straight line portion of the knife blade 20), as shown in FIG. Scanning is performed in the X direction (that is, the direction perpendicular to the straight line portion of the knife edge 20) while vibrating at an extremely high speed. That is, the surface of the knife 20 is scanned. Through such scanning, the ion beam that has passed through the knife 4 is collected by the Faraday cup 21,
The beam current based on the ion beam is the amplifier 22, A
It is obtained by the CPU 7 via the D converter 23. The waveform representing the amount of change in beam current with respect to scanning time is, for example,
When the ion beam scans from left to right, the changing waveform is similar to that shown in FIG. 3 above.

The CPU 7 measures the beam diameter from the scanning time t0 between I9°, which corresponds to 90% of the maximum value of the beam current amount, and 110°, which corresponds to 10%, in the same manner as described above.

Here, the dose amount will be compared between the case where the ion beam is line-scanned over the Knife-Fuji 20 as in the conventional method and the case where the ion beam is surface-scanned as in the present invention.

The dose is the amount of ions per unit area, and the ion beam current per unit area is I.

[A], scanning time t [sec], scanning area S [cm
2, the dose amount D [1 ons/cm2 is determined by equation (1).

D= (Ip X t)/ (1,6X10-19XS
)・・・・・・・・・・・・・・・(1) Now, ■, 1
00pA, beam diameter 0. When calculating the dose when a 1 μm ion beam is scanned over the knife 20 by 10 μm and 11 Qsec, in conventional scanning, Dl - (100XIO-12Xl0) / (1,6X
10-19XIOXIO-'X0. IX 10-')
-6.25X10” [1 ons/cm2].

On the other hand, in the scanning of the present invention, since the scanning is performed at a high speed of 5 μm in the Y direction, the scanning area is 510. 1 times, that is, 50 times, and the dose amount D2 at that time is D2- ((100xlO-12XIO)/(1,6x
10-19xlOxlO-'X5X10-')1 = 1.25X1016 [ion s/cm2. As a result, the dose amount of the surface scanning according to the present invention is reduced to (1150) of that of the conventional line scanning, and etching becomes less likely to occur.As a result, the beam diameter can be measured accurately.

Although a knife was used in the above embodiment, a shield having a straight portion such as a metal wire may also be used.

Such a beam diameter measuring method is also applied to measuring the diameter of an electron beam.

(Effects of the Invention) In the present invention, since the focused charged particle beam is scanned at high speed in a direction parallel to the straight line part of the shielding body and in a direction perpendicular to the straight line part, the point on the shielding body is The shielding material is less likely to be etched as the dose per area is reduced. Therefore, the diameter of the beam can be measured accurately.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an ion beam diameter measuring device showing an embodiment of the present invention, FIG. 2 is a schematic diagram of an electron beam diameter measuring device used to explain a conventional beam diameter measuring method, and FIG. Figure 3 is a diagram showing the amount of change in beam current with respect to scanning time, Figures 4 (a) and (b) are waveform diagrams representing scanning signals sent from the CPU to the X-direction deflector and Y-direction deflector, respectively. FIG. 5 shows the locus of the ion beam when it scans over the knife in the present invention. 1: electron gun, 2: focusing lens, 3: deflector, 4: knife, 5 amplifier, 6: DA converter, 7: control device,
8: Faraday cup, 9: Ambient 10: AD converter, 11: Ion gun, 12: Focusing lens, 13: X-direction deflector, 14: X-direction amplifier, 15: X-direction DA converter,
16: Y direction deflector, 17: Y direction amplifier, 18: Y direction DA converter, 19: control device, 20: knife,
21: Faraday Cup, 22: Amplifier, 23: AD
Converter patent applicant: Japan Electronics Co., Ltd. Figure 1゜2゜3゜Display of case 1990 Patent application No. 48521, Title of invention Relationship to case concerning a person who corrects the beam diameter measurement method of a focused charged particle beam Patent application Address: 3-1-2 Musashino, Akishima City, Tokyo (TEL
0425 (42) 2165) Procedural amendment (method) Display of the case Patent Application No. 48521 of 1990 Name of the invention Person who corrects the method for measuring the beam diameter of a focused charged particle beam Relationship to the case Patent applicant address Akishima, Tokyo 3-1-2 Musashino City (T.E.L.
0425 (42) 2165) 6. Contents of amendment (1) Lines 4 to 6 on page 9 of the specification are amended as follows. ``Figure 4 is a waveform diagram showing the scanning signal, Figure 5 is a diagram showing the amount of change in between.''

Claims (1)

[Claims] In a focused charged beam diameter measurement method in which a focused charged particle beam is scanned over a shielding body having a straight portion and a beam diameter is measured based on a beam information signal obtained by the scanning, the focused charged particle beam is While scanning the particle beam at high speed in a direction parallel to the straight part of the shield,
A method for measuring the diameter of a focused charged particle beam that scans in a direction perpendicular to the straight line.