JPH0218848A - Charged particle beam device - Google Patents

Abstract

PURPOSE:To form the deceleration field with low aberration by arranging an auxiliary electrode between a focusing lens and a decelerating electrode and applying the voltage to this auxiliary electrode. CONSTITUTION:An auxiliary electrode 10 is provided between an objective lens 2 and a decelerating electrode 8, an intermediate potential between the potential of the outside electrode of the objective lens 2 and the potential of the decelerating electrode 8 is applied to this auxiliary electrode 10. The decelerating voltage of about 30kV is applied to a target 3 and the decelerating electrode 8 by power sources 11 and 12, 10kV is applied to the auxiliary electrode 10 by the power source 11, for example. The aberration due to the objective lens and the deceleration field is sharply reduced.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device that focuses an ion beam or an electron beam on a target, and in particular, a device that decelerates a charged particle beam and irradiates the target with it. This invention relates to a charged particle beam device.

(Prior art) Figure 2 shows a conventional ion beam device.
is the ion source. An ion beam generated from an ion source 1 and accelerated to JJII speed is focused onto a target lens 1-3 by an objective lens 2. The objective lens 2 has a center electrode 5 to which a lens voltage is applied from a power source 4 and an outer electrode 6 at ground potential.
A deceleration voltage is applied between the outer electrode 6 and the target 3 from an ffi source 7.

With this configuration, the ion beam 11 is accelerated in the ion source 1 with an acceleration voltage of, for example, 30 kV, and this accelerated ion beam is decelerated by applying a voltage of 27 kV to the target 3, for example, to land at 3 kV. Target 3 is irradiated with energy. As a result, since the ion beam abrades the objective lens 2 with high energy, the lens aberration of the objective lens is suppressed to a low level, and the ion beam is narrowly focused on the target 3.

Also, since the target 3 is irradiated with the ion beam at a reduced speed, the Ω of the ion beam irradiation point on the target 3 is
Mountains are prevented.

In the configuration shown in FIG. 2 above, since the deceleration electric field is directly exposed to the target 3, there are problems such as the secondary electrons cannot be detected or the ion beam is incorrectly deflected as the target moves. there were. FIG. 3 shows an ion beam focusing system designed to solve this problem, and the same parts as in FIG. 2 are given the same numbers.

In the configuration shown in FIG. 3, a deceleration electrode 8 having the same potential as the target 3 is placed between the objective lens 2 and the target 3, and a secondary electron detector 9 is placed between the deceleration electrode 8 and the target 3. be done. With this configuration, the surface of the target 3 is not directly exposed to the deceleration electric field, making it possible to detect secondary electrons. Also, target 3
Even if the ion beam is moved, the deceleration electric field will not be disturbed and the ion beam will not be improperly deflected.

(Problem to be Solved by the Invention) FIG. 4 shows the objective lens 2° deceleration electrode 8. The on-axis potential near target 3 is shown. The line B shows the case where the deceleration electrode 8 is not provided, and the line B shows the case where the deceleration electrode 8 is provided.

In this example, the acceleration energy of the ion beam is 30kV
, and the landing energy is 1 kV. In the line to , the potential distribution is linear and the lens aberrations due to the objective lens and the retarding electric field are low. On the other hand, in line B, the potential drops to approximately 1 kV at a position quite far from the target 3, and the aberration of the lens due to the deceleration electric field increases, and this sudden change in potency causes the ion beam to become focused. The point ends up being in front of the target 3 surface.

The present invention has been made in view of these points, and its purpose is to realize a charged particle beam device that can form a deceleration electric field with low aberrations.

(Means for Solving the Problems) A charged particle beam device based on the present invention includes a charged particle beam source and a focusing lens for narrowly focusing a charged particle beam generated from the charged particle beam source and accelerated onto a target. a deceleration means for interposing a deceleration electric field that decelerates the charged particle beam between the focusing lens and the target; and a deceleration electrode disposed between the focusing lens and the target and having approximately the same potential as the target. The charged particle beam device is characterized in that an auxiliary electrode is disposed between the focusing lens and the deceleration electrode, and a voltage is applied to the auxiliary electrode.

(Function) A deceleration electrode is placed between the focusing lens and the target, and an auxiliary electrode is placed between the focusing lens and the deceleration electrode,
A high voltage is applied to this auxiliary electrode to reduce aberrations caused by the deceleration electric field.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the main parts of an ion beam apparatus according to the present invention, and the same parts as those of the conventional apparatus shown in FIG. 3 are given the same numbers. This embodiment is different from the conventional device shown in FIG. 3 in that an auxiliary electrode 10 is provided between the objective lens 2 and the deceleration electrode 8. This is the point where a potential intermediate between the potential of the outer electrode of the objective lens 2 and the potential of the deceleration electrode 8 is applied to the auxiliary electrode 10. That is, at power supply 11.12,
30kVP to target 3 and deceleration electrode 8? A deceleration voltage of, for example, 10 kV is applied to the auxiliary electrode 10 by the power source 11.

With this configuration, aberrations caused by the objective lens and the deceleration electric field are significantly reduced. Table 1 below shows the calculated chromatic aberration coefficient CC and magnification M. ■ indicates that the ion beam is decelerated between the objective lens 2 and the target 3, and the deceleration electrode and auxiliary electrode are arranged. If not, ■, if deceleration electrode 8 is provided, ■ and ■
This is the case where both the deceleration electrode 8 and the auxiliary electrode are arranged.

In either case, the acceleration voltage of the ion beam is 30 kV, and the landing energy is 1 kV. Further, the potential of the auxiliary electrode in the case of ■ is 10 kV, and the potential of the auxiliary electrode in the case of ■ is 5 kV.

Table 1 Cc M ■ 0,9 0,31 ■ 3.5 0.18 ■ 1,0 0,25 ■ 1,4 -0.27 According to Table 1 above, auxiliary electrode 10@ is provided, and this auxiliary ? 1
! It can be seen that by applying a voltage to the pole, the chromatic aberration coefficient can be significantly reduced compared to the case (■) without the auxiliary electrode. Also, the magnification is close to the value when no deceleration electric field is provided (■), and the focal point is prevented from changing in a mossy manner.

In the embodiment L, one auxiliary electrode is provided, but this auxiliary electrode may be provided in multiple stages. Further, although the ion beam device has been described as an example, the present invention can also be applied to an electron beam device that irradiates a target with an electron beam at a reduced speed.

(Effects of the Invention) As explained in detail above, in the present invention, an auxiliary pole is arranged between the focusing lens and the deceleration electrode, and a voltage is applied to the auxiliary electrode, so that the deceleration electric field is Aberrations can be reduced, and changes in the focal point of the beam due to the deceleration electric field can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main parts of an ion beam device that is an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing a conventional ion beam device, and FIG. FIG. 3 is a diagram showing an axial potential distribution. 1... Ion source 2 Objective lens 3... Target 4... Power source 5... Center electrode
6... Outer electrode 7... Power supply 8.
...Deceleration electrode 9...Secondary electron detection i%f 1o...
・Auxiliary electrode 11.12... Power supply patent applicant Japan Electronics Co., Ltd.
Ceremony for the meeting Patent attorney
Fuji Ijima, 1 person, 2nd entrance, figure 3, figure 4, planting

Claims (1)

[Claims] A charged particle beam source, a focusing lens for narrowly focusing the accelerated charged particle beam generated from the charged particle beam source onto a target, and a deceleration electric field for decelerating the charged particle beam between the focusing lens and the target. In a charged particle beam device comprising a deceleration means for generating and a deceleration electrode arranged between a focusing lens and a target and having substantially the same potential as the target, an auxiliary electrode is arranged between the focusing lens and the deceleration electrode, A charged particle beam device characterized in that it is configured to apply a voltage to an auxiliary electrode.