JPH0575280B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an E×B speed separator.

(Prior Art) In recent years, ion beam apparatuses using field emission ion sources have been developed to form microprobes and are used for ultrafine processing of semiconductor substrates and the like. An E×B velocity selector, also called a Wien filter, is installed in such an ion beam device and selects a desired ion beam from among ion beams with various velocity distributions depending on the charge, mass, etc. of the ions emitted from the ion source. It is used for the purpose of extracting an ion beam with only a velocity of .

By the way, when trying to use an ion beam for ultra-fine processing, etc., in addition to the E×B speed selector,
Components such as a deflector for controlling the ion beam irradiation position and a lens for focusing the ion beam are essential to an ion beam apparatus.

In an ion beam device, in order to obtain a high-quality beam with low aberrations, the central axis (optical axis) of the device components, such as the focusing lens, aligner, and deflector, must be However, ideal mechanical assembly is extremely difficult in reality, as the optical axis must be matched within a few micrometers compared to the drift length of the ion beam, which is several tens of centimeters. Yes, for example, if both the astigmatism corrector and deflector are misaligned,
This causes problems such as astigmatism correction becoming impossible and deflection aberration increasing.

Furthermore, when the number of constituent members of the apparatus increases, the space is occupied accordingly, resulting in a disadvantage that the drift length of the ion beam becomes longer.

In other words, as the drift length becomes longer, it becomes more susceptible to the effects of external disturbances and the space charge of the ion beam itself.Furthermore, the focusing lens is required to have a long focal length to match the long drift length, and the optical properties also deteriorate. This has an adverse effect, resulting in a problem that deteriorates the quality of the ion beam.

Therefore, if there are fewer components, the chance of axis misalignment occurring is reduced, and the drift length can be shortened, making it less susceptible to the above-mentioned disturbances and improving optical characteristics. I can do it.

Therefore, it is strongly desired that the number of constituent members be small and small.

(Objective of the Invention) An object of the present invention is to solve the above problems, shorten the drift length of an ion beam, and provide a high-quality ion beam.

(Means for Solving the Problems) The first invention of the present application provides electrodes that are arranged opposite to each other to form an electrostatic field; An electromagnetic multipole having a quadrupole or more is constituted by magnetic poles that form an electrostatic field, and at least two of the electromagnetic multipoles are subordinated to each other through an optical axis and an aperture hole provided in the optical axis castle. It is possible to independently apply a voltage to each of the electrodes and magnetic poles of such an electromagnetic multipole, and one of the electrode multipoles connects to the other electromagnetic multipole in a plane perpendicular to the optical axis. The above object has been achieved by using an E×B speed selector which is capable of forming an electrostatic field in the opposite direction to that of the E×B speed selector.

Further, a second invention of the present application provides: electrodes that are arranged to face each other to form an electrostatic field; and magnetic poles that are arranged to face each other to form a static magnetic field that intersects the electrostatic field: constitutes an electromagnetic multipole of quadrupole or more, and it is possible to apply a voltage independently to each of the electrodes and magnetic poles of the electrode multipole, and furthermore, the electrodes are arranged opposite to each other. An electric multipole of quadrupole or higher is constructed by comprising electrodes that form an electrostatic field, and the electric multipole and the electromagnetic multipole are connected in a subordinate manner through a common optical axis and an aperture hole disposed on the optical axis. The electric multipole is placed in the same direction as the electric multipole, and an E×B velocity selector is capable of forming an electrostatic field in the opposite direction to the electric multipole in a plane perpendicular to the optical axis. The purpose has been achieved.

(Example) FIG. 1 shows an embodiment of the present invention.

First, the ion beam traveling direction (optical axis) is set as the Z-axis 1, and an electrode pair is formed by two parallel plate non-magnetic electrodes 2 and 3 so as to narrow the optical axis, and an electric field E1 is formed in the Y-axis direction. Further narrowing the optical axis, the two parallel plate magnetic electrodes 4 and 5 form a magnetic pole pair to form a magnetic field B1 in the X-axis direction.

In this case, the magnetic field B1 is orthogonal to the electric field E1 described above, and an electromagnetic quadrupole is configured by the electrode pair and the magnetic pole pair.

6 is a diaphragm member, and 60 is a diaphragm hole disposed at a position where the diaphragm member 6 intersects with the optical axis Z1.

Here, between the electromagnetic quadrupole and the aperture member 6,
By arranging an electromagnetic quadrupole with the same configuration as the electromagnetic quadrupole with the optical axis and aperture hole 60 in common,
The ExB speed selector of the present invention is composed of two stages of electromagnetic quadrupoles connected in cascade.

7 and 8 are electrode pairs in the second stage electromagnetic quadrupole,
Reference numerals 9 and 10 indicate a pair of magnetic poles, and the electrode pair 7 and 8 form an electric field E2 in the Y-axis direction, and the magnetic pole phases 9 and 10 form a magnetic field B2 in the X-axis direction. Reference numeral 11 indicates a sample to be irradiated with the ion beam.

Further, FIG. 2a shows a cross section of the main part of the E×B speed selector on the YZ plane including the Z axis (optical axis) 1 in FIG. 1.

The operating principle is as follows.

In Figure 2b, the magnetic field B acting in the -X direction
1, the ion beam is deflected in the -Y direction within the first-stage electromagnetic quadrupole, and the ion beam,
Due to the difference in the speed of

Here, where v is the speed of the ion beam and v is the speed of the ion beam, if v>v, the ion beam is largely deflected. Furthermore, if an electric field E1 acting in the -Y direction is applied,
The ion beam is further deflected in the -Y direction by this electric field E1.

The ion beam enters the second stage electromagnetic quadrupole while being deflected in the −Y direction by the first stage electromagnetic quadrupole. When an electric field E2 acting in the +Y direction is applied to the electromagnetic quadrupole, the ion beam is deflected in the +Y direction.

Here, if there is a magnetic field B2 acting in the -X direction,
Furthermore, the difference in the degree of deflection from the ion beam increases, making it easier to separate the beam from the ion beam.

Next, if you select an appropriate E2, as shown in the figure,
Only the ion beam can pass through the aperture hole 6 to irradiate the sample 11.

In Fig. 2c, the velocity of the ion beam v
But, v=(0,0,E1/B1)=(0,0,E
2/B2), only the ion beam goes straight and passes through the aperture hole 60, and the sample 11
You can irradiate the top.

In Fig. 2d, the electric field E1 of the first-stage electromagnetic quadrupole acts in the +Y direction, and the ion beam is separated by the difference in velocity due to the magnetic field B1 and deflected in the -Y direction. is deflected in the +Y direction.

This case can be considered in the same manner as in FIG. 2b, and the ion beam enters the second stage electromagnetic quadrupole while being deflected in the +Y direction by the first stage electromagnetic quadrupole. In the second stage quadrupole, -Y
When an electric field E2 acting in the direction is applied, the ion beam is deflected in the -Y direction.

If an appropriate electric field E2 is selected here, only the ion beam along the line shown in the figure can be passed through the aperture hole 60 and irradiated onto the sample 11.

As mentioned above, the magnetic field B1 of the first stage electromagnetic quadrupole,
Or magnetic field B1 and magnetic field B2 of the second stage electromagnetic quadrupole
Y of the two-stage electromagnetic quadrupole with reference to both of
By controlling the electric fields E1 and E2 in the directions, only the ion beam with the desired velocity is directed to the aperture hole 60.
The sample 11 can be scanned in the Y direction.

Therefore, if a voltage is also applied to the magnetic electrodes located in the X direction of the two-stage electromagnetic quadrupole to form an electric field in the X direction, it is possible to scan the sample 11 in the X direction in the same way, and both By combining sample 1
1 can be scanned in the XY plane direction with an ion beam having a desired speed.

In this embodiment, the multipole is described as a quadrupole, but the same effect can be obtained even if the multipole is an octupole. In addition, if it is impossible to apply a voltage to the magnetic pole because the magnetic pole is an insulator, a non-magnetic electrode may be placed in front of the magnetic material that makes up the magnetic pole on the optical axis side, as shown in Figure 3. Even if an electric field is created by applying a voltage to this, the effect is the same.

The structure of the second invention of the present application is the same as the second invention described above, and its operation is as described in the description of the above embodiment, except that the magnetic field is removed from the second stage electromagnetic quadrupole. The operation can be easily inferred by omitting . Therefore, the explanation will be omitted.
Note that the second-stage electromagnetic quadrupole from which the magnetic field is removed will be referred to as an electric quadrupole.

In this case, even if the front and rear stages of the subordinate connection of the electromagnetic quadrupole and the electric quadrupole are reversely connected, the operating principle remains the same.

Furthermore, if these electromagnetic multipoles or electric multipoles are used as octupole elements to control voltage application, astigmatism correction can be performed, and such multipole elements may be connected in cascade in three or more stages.

(Effects of the Invention) The E×B speed selector of the present invention can be used as a deflector, astigmatism corrector, aligner for optical axis adjustment, or any combination thereof, and space can be saved when configuring an optical system. It has the effect of improving optical properties.

[Brief explanation of the drawing]

FIG. 1 is an explanatory perspective view of an embodiment of the E×B speed selector of the present invention. Figure 2 a, b, c, d are the first
A sectional view of the main part of the figure, used to explain the principle of operation. FIG. 3 is a sectional view of a main part of another embodiment of the E×B speed selector of the present invention. 1... Optical axis (Z axis), 2, 3, 7, 8... Non-magnetic electrode, 4, 5, 9, 10... Magnetic electrode, 6...
Aperture hole, 11...sample, 60...aperture member.

Claims (1)

[Claims] 1. Electrodes that are arranged to face each other to form an electrostatic field; and magnetic poles that are arranged to face each other to form an electrostatic field that intersects the electrostatic field. constitute an electromagnetic multipole of quadrupole or more, and at least two of the electromagnetic multipoles are arranged in a cascading manner with an optical axis and an aperture hole disposed on the optical axis in common; Voltages can be applied independently to all electrodes and magnetic poles, and one of the electrode multipoles forms an electrostatic field in the opposite direction to the other electromagnetic multipoles in a plane perpendicular to the optical axis. An ExB speed selector characterized by being capable of. 2. An electromagnetic device having a quadrupole or more, comprising: electrodes that are arranged to face each other to form an electrostatic field; and magnetic poles that are arranged to face each other to form a static magnetic field that intersects the electrostatic field. It constitutes a multipole element, and is capable of independently applying a voltage to each of the electrodes and magnetic poles of the electrode multipole element, and further includes electrodes that are arranged to face each other to form an electrostatic field. constitute an electric multipole of quadrupole or more, and the electric multipole and the electromagnetic multipole are arranged in a cascading manner with the optical axis and the aperture hole disposed on the optical axis in common. E× characterized in that the pole is capable of forming an electrostatic field in the opposite direction to the electrode multipole in a plane perpendicular to the optical axis.
B speed sorter.