JPH0619962B2 - Charge beam device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a charged beam apparatus for irradiating a sample or the like with a charged beam.

(Prior Art) A conventional apparatus shown in FIG. 3 is a diaphragm member in which a charged particle beam source 1 and a plurality of diaphragm holes 4a to 4c (opening diameters are, for example, 10 to 100 μm) having different opening diameters are formed. 5 (thickness is 10 μm, for example), a focusing lens 6, a deflector 7, a secondary electron detector 9, a deflection amplifier 10, and a CRT display 11.

In the figure, reference numeral 3 is an optical axis, and 8 is a sample.

Then, the diaphragm member 5 is movable in the horizontal direction, and one of the diaphragm holes is located below the charged beam generating source 1.

Then, the charged beam 2 output from the charged beam generation source 1 passes through the desired aperture hole selected as described above, passes through the focusing lens 6 and the deflector 7, and is irradiated onto the sample 8. Since the deflection amplifier 10 is connected to the deflector 7, the charged beam 2 can be scanned on the sample 8 by controlling the deflection amplifier 10. Also,
The focusing intensity of the focusing lens 6 is controlled based on the signal from the control power supply 12.

When the sample 8 is irradiated with the charged beam 2 as described above, secondary electrons are generated from the sample 8. The secondary electrons are detected by the secondary electron detector 9. Then, this detection signal is sent to the CRT
When sent to the display 11 and synchronized with the scanning signal of the deflection amplifier 10, the scanning secondary electron image of the sample 8 is displayed on the display 11.

The beam diameter and the amount of current of the charged beam 2 with which the sample 8 is irradiated at this time depend on the diameters of the aperture holes 4a to 4c on the aperture member 5.

Therefore, in order to obtain a charged beam having a desired beam diameter or current amount, the diaphragm member 5 is moved horizontally to generate one of the diaphragm holes 4a to 4c having an appropriate aperture diameter. It must be located below the source 1.

However, in order to obtain a charged beam of high quality, the center of the aperture and the optical axis 3 must be aligned. If the optical axis 3 does not coincide with the center of the aperture, the trajectory of the charged beam 2 deviates from the optical axis 3 and the influence of aberration increases. However, if the influence of this aberration increases, the cross section of the charged beam will change. The quality of the charged beam is deteriorated by asymmetrically distorting or increasing the beam diameter more than necessary.

Therefore, conventionally, the work of aligning the optical axis with the center of the aperture hole (hereinafter referred to as optical axis adjustment) has been performed as follows.

First, the desired aperture is simply located below the charged beam generator 1. By thus arranging the diaphragm hole below the charged beam generating source 1, the charged beam 2 reaches the sample 8 even if the optical axis 3 and the center of the diaphragm hole do not coincide. Therefore, if the deflection amplifier 10 is operated, the CRT
The scanning secondary electron image can be observed on the display 11.

At this time, if the intensity of the focusing lens is changed, the scanning secondary electron image flows on the screen of the CRT display 11 when the optical axis adjustment for aligning the optical axis 3 with the center of the aperture is not accurate. Can be seen.

Therefore, while changing the intensity of the focusing lens,
The optical axis can be adjusted by controlling the relative position of the aperture hole with respect to the optical axis 3 until the scanning secondary electron image does not flow on the screen of the CRT display 11.

(Problems to be Solved by the Present Invention) If the aperture diameter of the selected aperture hole is large, the beam diameter is correspondingly large. However, the larger the beam diameter is, the obtained scanning secondary electrons are obtained. Image resolution is poor. If the resolution of the scanning secondary electron image deteriorates, it becomes impossible to accurately adjust the optical axis based on the scanning secondary electron image.

Therefore, in the conventional apparatus, there is a problem that the accuracy of the optical axis adjustment decreases as the aperture diameter of the diaphragm hole increases.

According to the present invention, an auxiliary diaphragm member having a small diameter auxiliary diaphragm hole is provided between a diaphragm member and a charged beam generating source, and the diaphragm hole is formed with a constant accuracy regardless of the aperture diameter of the diaphragm hole formed in the diaphragm member. It is an object of the present invention to provide a charged particle beam system capable of accurately aligning the optical axes of the above.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention has means for controlling the relative position between the diaphragm hole formed in the diaphragm member and the optical axis of the charged beam, and the diaphragm One of a plurality of aperture holes having different aperture shapes and aperture dimensions or one of them provided on the member is selected, and the aperture is used to aperture the charged beam generated from the charged beam source. In a charged beam apparatus for irradiating a sample with the charged beam thus generated, an auxiliary diaphragm member is provided between the charged beam source and the diaphragm member, and the auxiliary diaphragm member has a circular hole whose size is the diaphragm hole. Of the auxiliary throttle having the same diameter as or smaller than the smallest diameter of the auxiliary throttle, and this auxiliary throttle member is capable of switching between an operating position and an inactive position, and in the operating position, the auxiliary throttle is provided. The center of the hole is the load The configuration is such that it coincides with the optical axis of the electric beam and deviates from the irradiation portion of the charged beam at the non-acting position so as not to act on the charged beam.

(Operation of the present invention) Since the present invention is configured as described above, the beam from the charged beam generating source is irradiated with the auxiliary diaphragm member in the operating position. When the auxiliary diaphragm member is in the operating position and the optical axis alignment of the diaphragm hole of the auxiliary diaphragm member smaller than the diaphragm hole diameter has been completed, the optical axis alignment of a constant accuracy is achieved regardless of the aperture diameter of the diaphragm hole of the diaphragm member. To be achieved.

Then, the optical axis is aligned with the charged beam that has passed through the aperture of the auxiliary aperture member.

(Object of the Invention) According to the charged beam apparatus of the present invention, the accuracy of the optical axis alignment of the auxiliary diaphragm hole of the auxiliary diaphragm member is improved. The optical axis of the diaphragm hole of the diaphragm member for axis alignment can be accurately aligned.

(Example of the present invention) An example of the present invention is shown in Figs.

In FIG. 1, 51 is a charged beam generating source 1 and a diaphragm member 5.
An auxiliary diaphragm member 41 provided between the auxiliary diaphragm member 51 and the auxiliary diaphragm member 51 is formed with an auxiliary diaphragm hole 41 having the same diameter as the diaphragm hole 4a having the smallest diameter of the diaphragm member 5 or a diameter smaller than that (for example, 9 μm). is doing. If the diameter of the auxiliary aperture hole 41 is larger than the diameter of the aperture hole of the aperture member 5, the accuracy of the optical axis alignment of the auxiliary aperture hole 41 may be lower than the accuracy of the optical axis alignment of the aperture hole member 5.

The auxiliary diaphragm member 51 is horizontally moved by the driving device 13 to be located at two positions, that is, the working position a where the center of the auxiliary diaphragm hole 41 coincides with the optical axis 3 and the non-working position b where the charging beam 2 is not irradiated. It can be switched. The driving device 13 is controlled by the output signal of the central controller 17.

The diaphragm member 5 is connected to the diaphragm member 5 and can be horizontally moved in at least two directions by the driving force of the driving device 14. The drive unit 14 is also controlled by the output signal of the central control unit 17, like the drive unit 13.

Further, the diaphragm member 5 has an ammeter 15 and the sample 8 has an ammeter 16
Are electrically connected, and the signals of these two ammeters 15, 16 are sent to the central controller 17.

The configuration other than the above is almost the same as the description of the conventional device.

Then, any one of the diaphragm holes 4a to 4c on the diaphragm member 5, for example, the diaphragm hole 4a is selected and positioned below the charged particle beam generation source 1. Along with this, the auxiliary throttle member
51 is set to the action position a and the charged particle beam source 1 irradiates the charged particle beam 2.

In this state, the driving device 14 is driven to horizontally move the diaphragm member 5 and relatively move the charged beam 2 and the diaphragm member 5.
By doing so, the same result as when the charged beam 2 is scanned in the diametrical direction having the aperture 4a is obtained. Then, while the charged beam 2 is irradiating the inside of the aperture 4a, the current due to the irradiation of the charged beam 2 does not flow through the aperture member 5, but the charged beam 2 comes out of the aperture 4a and the aperture member 5 is opened. During direct irradiation, current flows through the diaphragm member 5.

Therefore, if the charged beam 2 is scanned in one diametrical direction of the diaphragm hole 4a, the current decreases from one end X position of the diameter line of the diaphragm hole 4a to zero as shown in FIG. The current increases again from the other end Y of the line. The current change is detected by the ammeter 15 and the signal is sent to the central controller 17.

In this way, the central controller 17 that receives the signal from the ammeter 15
Then, the positions X and Y at which the current changes are stored, the distance between the positions X and Y is divided by 2, and one diametrical center of the throttle hole 4a is obtained and stored. If this scanning is performed in a plurality of directions, the aperture 4a
It is possible to accurately specify the center position of the aperture hole 4a regardless of the diameter of the aperture, and to store the accurately specified center position of the diaphragm hole 4a in the central controller 17.

In this way, with respect to the other diaphragm holes of the diaphragm member 5,
It is also possible to specify the center position of this hole and store it in the storage device 18 connected to the central controller. If all the central positions of the respective aperture holes are stored in the central controller 17, for example, when the sample is being processed by the charged beam and the aperture holes are changed to continue processing with another beam diameter, Even if the aperture hole is changed during processing, the center position of the aperture hole is specified in advance, so there is an advantage that the optical axis need not be adjusted each time.

In the above description, the center of the diaphragm hole is obtained while the current flowing through the diaphragm member 5 is detected by the ammeter 15, but the center of the diaphragm hole is determined by using the ammeter 16 connected to the sample 8. You may ask.

Then, when the optical axis is adjusted using the ammeter 16, it is as follows. That is, when the small-diameter charged beam that has passed through the auxiliary aperture hole 41 is inside the aperture hole 4a, the sample 8 is irradiated with the charged beam, so that a current flows through the sample 8. On the contrary, when the charged beam is out of the aperture, the charged beam is blocked by the aperture member 5, so that no current flows in the sample 8. Therefore, the output signal of the ammeter 16 has a characteristic that the level of the current is opposite to the characteristic shown in FIG.

A secondary electron detector 9 or a secondary ion detector 19 may be used in place of the ammeter 16 as described above, or the ammeter 16, the secondary electron detector 9 or the secondary ion detector 19 may be used.
You may use in combination.

Further, a well-known piezoelectric element utilizing device (JJAPPL.PHYS.24 (1985) P152 to P155) which enables fine movement in at least two directions, the driving device 14 of the diaphragm member 5 and the driving device 13 of the auxiliary diaphragm member 51.
(See), the relative position of the diaphragm member or the auxiliary diaphragm member and the optical axis can be controlled with high accuracy, and in the case of using a laser length measuring device together,
Further, the accuracy of measuring the position of the diaphragm member is improved.

The shapes of the auxiliary throttle hole 41 and the throttle holes 4a to 4c are not limited to circular shapes, and may be other shapes such as a quadrangle.

Further, the present invention is effective for all charged beam devices having a diaphragm member.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention.
FIG. 3 is a schematic diagram, FIG. 2 is a graph showing the state of current change with respect to the movement amount of the diaphragm member, and FIG. 1 ... Charged beam generation source, 2 ... Charged beam, 3 ... Optical axis, 4a-4c ... Aperture hole, 5 ... Aperture member, 13, 14 ...
… Drive device, 17 …… Control device, 41 …… Auxiliary hole, 51 …… Auxiliary diaphragm member.

Claims (4)

[Claims] 1. A means for controlling a relative position between a diaphragm hole formed in a diaphragm member and an optical axis of a charged beam, wherein the shape of the hole and / or the size of the hole provided in the diaphragm member, respectively. In one of a plurality of different aperture holes, a charged beam device for irradiating a sample with the focused beam emitted from a charged beam generating source and irradiating the focused beam to the sample An auxiliary diaphragm member is provided between the source and the diaphragm member, and the auxiliary diaphragm member has a circular hole whose diameter is the same as or smaller than the smallest of the diaphragm holes. A hole is formed, and this auxiliary diaphragm member can switch between an operating position and a non-operating position. In the operating position, the center of the auxiliary diaphragm hole coincides with the optical axis of the charged beam, and in the non-operating position, Irradiation of charged beam Charged beam apparatus wherein deviates from minute the charged beam that has a configuration that does not result in action. 2. The charged particle beam apparatus according to claim 1, wherein the position of the diaphragm member is changed and the relative position of the diaphragm hole and the charged beam optical axis is controlled by a driving mechanism. Charged beam device. 3. The charged particle beam apparatus according to claim 1, wherein the driving mechanism is composed of a piezoelectric element capable of fine movement in at least two directions. 4. A charged particle beam apparatus according to claim 1 or 2, further comprising a controller for controlling a drive mechanism.