JPH02121247A - Charged particle beam compound device - Google Patents

Abstract

PURPOSE:To make it possible to scan electron beams and ion beams simultaneously and in the same area by leading the electron beams and the ion beams on a same optical axis to enable to radiate the both beams on a target, and converting the both beams at a high speed to radiate on the target. CONSTITUTION:Electron beams EB from an electron gun 1 and ion beams IB from an ion gun 2 are injected into an electrostatic deflecting prism 20, and either the electron beams or the ion beams pass through the aperture of an aperture plate 22 responding to the voltage applied to the deflecting prism 20 from a power source 21. The beams passing through the aperture plate 22 are focused slenderly on a target 7 by an object lens 6, while the radiation position on the target 7 is converted responding to the voltage applied to an electrostatic deflecting plate 23. Consequently, both beams can be radiated independently in a desired area.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention irradiates a target with an ion beam and an electron beam. The present invention relates to a charged particle beam composite device capable of simultaneously performing surface observation.

(Prior Art) A tC defect correction device using a focused ion beam device has become a very important device for shortening the development period as a tool for manufacturing new devices. This equipment first observes the pattern using an optical microscope, etc., confirms the defective area, and then irradiates the defective area with an ion beam to remove the defective area by etching, or deposits the necessary ions onto the defective area. We are trying to correct defects by doing so.

However, in this device, the resolution of the optical microscope is low, making it inadequate for repairing miniaturized ICs.

Furthermore, in the Auger electron analyzer, Auger electrons generated from a target such as a sample by electron beam irradiation are spectrally analyzed to analyze the sample. In this device, in order to perform depth analysis, an ion source such as a duoplasmatron is attached to the side of the electron beam column, and the ion beam from this ion source is irradiated onto the sample, etching the sample while etching the electrons. A beam is irradiated to perform analysis and observation.

In this method, it is troublesome to align the axes of the electron beam and ion beam, and because the sample is irradiated with a relatively large ion beam from the duo-plasmatron ion source, it is difficult to etch small areas. Have difficulty.

(Problem to be solved by the invention) In order to solve this problem, the electron beam shown in FIG.
A combined ion beam device is being considered.

In this device, an electron gun 1 and an ion gun 2 are mounted on the same column. Electron beam EB from electron gun 1
is focused by a focusing lens 3, the ion beam IB from the ion gun 2 is focused by a focusing lens 4,
Both beams form a crossover at the center of the electromagnetic deflector 5.

The electron beam and ion beam are aligned on the same optical axis O by an electromagnetic deflector 5, and a composite beam CB of the electron beam and ion beam is narrowly focused onto a target 7 by an objective lens 6. The objective lens 6 is composed of an electrostatic lens 11 and an electromagnetic lens 12, and since the ion beam IB has a large mass, it is focused almost exclusively by the electrostatic lens 11, as shown by the solid line in the figure. Also, electron beam EB
is subjected to a focusing action by both the electrostatic lens 11 and the electromagnetic lens 12, as shown by the dotted line in the figure.

By appropriately adjusting the lens strengths of both the electrostatic lens 11 and the electromagnetic lens 12, the ion beam and electron beam can be narrowly focused onto the target 7 at the same time.

The irradiation positions of the electron beam and the ion beam on the target 7 are changed by the deflector 13.
It is composed of an electrostatic deflection plate 14 and a deflection coil 15.

Secondary electrons generated by irradiating the target 7 with the beam are detected by a secondary electron detector 16 such as a microchannel plate. A mesh electrode 17 is arranged between the target 7 and the secondary electron detector 16, and a voltage of approximately IOV is applied to the mesh electrode 17 from a power source 18.

The operation of the above-described configuration is as follows. When etching the surface of the target 7 with an ion beam and observing this etched portion with a secondary electron image produced by electron beam irradiation, the ion beam and electron beam are simultaneously narrowly focused by the objective lens 6 and irradiated onto the target 7. be done.

In order to scan the irradiation positions of the ion beam and electron beam on the target 7, a deflection signal (i%) is supplied to the deflector 13.

Now, without supplying a signal to the deflection coil 15, electrostatic (-)
If a deflection signal is supplied only to beam 4, electron beam EB and ion beam IB will be deflected only by the electric field. Since the electron beam and ion beam have opposite polarity of charge, they are deflected in opposite directions. Next, if a deflection signal is also supplied to the electromagnetic deflection coil 15, a deflection magnetic field is generated, but since ions have a large mass, they are hardly affected by this magnetic field. However, the electrons are strongly acted upon by the magnetic field, for example, if the force exerted by the magnetic field is much greater than the force exerted by the electrostatic field, the electron beam EB will be deflected to a greater extent in the same direction than the ion beam IB. If the forces exerted on the electron by the electrostatic electric field and the magnetic field are equal, the electron will not be deflected and will travel straight.

In this way, by appropriately adjusting the intensities of the electric field and magnetic field, it is possible to simultaneously scan a predetermined area on the target 7 with the electron beam and the ion beam. Of course, this scanning area can be arbitrarily changed by widening the electron beam and limiting the ion beam scanning area to the central part of the electron beam scanning area, or vice versa. However, in order to scan the same area with an electron beam and an ion beam, it is necessary to adjust the electromagnetic and electrostatic deflectors so that their operations perfectly match, but this adjustment work is extremely difficult. It's a hassle.

The present invention has been made in view of these points, and its purpose is to provide a charged particle beam composite device that can scan an electron beam and an ion beam substantially simultaneously in the same area without requiring troublesome adjustments. The aim is to realize this.

(Means for Solving the Problems) A charged particle beam composite device according to claim 1 of the present invention includes:
an ion beam generation source, an electron beam generation source, means for guiding the ion beam and the electron beam onto the same optical axis;
A switching means for rapidly switching between an ion beam and an electron beam and guiding them to a target; a lens for focusing the electron beam and the ion beam to be irradiated on the target; It is characterized by the fact that it can be seen that it has a deflection means for scanning.

The charged particle beam composite device according to claim 2 of the present invention includes:
an ion beam generation source, an electron beam generation source, means for guiding the ion beam and the electron beam onto the same optical axis;
A switching means for rapidly switching between an ion beam and an electron beam and guiding them to a target; a lens for focusing the electron beam and the ion beam to be irradiated on the target; It is characterized by comprising a deflection means for scanning the target and a control means for controlling the irradiation time of the electron beam and the ion beam to the target.

(Function) In the invention of claim 1, the electron beam and the ion beam are guided on the same optical axis, and the target is irradiated with the electron beam and the ion beam. A switching means is provided to irradiate the target with either the electron beam or the ion beam in a time-sharing manner.

In the invention of claim 2, the electron beam and the ion beam are guided on the same optical axis, and the target is configured to be irradiated with the electron beam and the ion beam, and the electron beam and the ion beam are switched at high speed. A switching means for irradiating the target is provided, and the target is irradiated with either the electron beam or the ion beam in a time-sharing manner. Furthermore,
A control means is provided to control the irradiation time of the electron beam and the ion beam so that the target is not charged up.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a charged particle beam device according to the present invention, and the same parts as in FIG. 6 are given the same numbers. The electron beam EB from the electron gun 1 and the ion beam IB from the ion gun 2 enter an electrostatic deflection prism 20, and a power source 21
Either an electron beam or an ion beam passes through the opening of the aperture plate 22 depending on the voltage applied to the deflection prism 20 from the deflection prism 20 . The beam passing through the aperture plate 22 is narrowly focused onto the target 7 by the objective lens 6, and the position of the beam 11 on the target 7 is changed according to the voltage applied to the electrostatic deflection plate 23. It will be done.

The electron beam EB is deflected when a voltage is applied from the blanking power supply 24 to the blanking electrode 25 and collides with the aperture plate 26, so that the electron beam EB is prevented from entering the deflection prism 20. The ion beam IB is deflected when a voltage is applied from the blanking power supply 27 to the blanking electrode 28 and collides with the aperture plate 29, so that the ion beam IB is prevented from entering the deflection prism 20.

The electrostatic deflection plate 23 includes a control device 30 such as a computer.
A scanning signal is supplied from the amplifier 31 through the amplifier 31 . This control device 30 includes the blanking power supplies 24, 27 . It controls the power supply 21 and supplies a scanning signal to a cathode ray tube 33 to which a secondary electron detection signal detected by the secondary electron detector 16 and amplified by the amplifier 32 is supplied.

The operation of the above-described configuration will be explained with reference to the signal waveforms shown in FIG. The control device 30 is connected to the cathode ray tube 33 as shown in FIG.
) is supplied.

Next, from the control device 30 to the electrostatic deflection plate 23, as shown in FIG.
A scanning signal in the X direction shown in b) and a scanning signal in the Y direction shown in FIG. 2(f) are supplied. The blanking electrode 25 of the electron beam is connected to the blanking power supply 24 as shown in FIG. 2(C).
The blanking signal shown in FIG. 2(d) is supplied from the blanking power supply 27 to the blanking electrode 28 of the ion beam. Figure 2 (
e) shows the deflection voltage applied to the deflection prism 20 from the power supply 21.

During the first scanning period T1 in the X direction in the cathode ray tube 33, a blanking voltage of +■ is applied to the electron beam blanking electrode 25, the electron beam is deflected and collides with the aperture plate 26, and the electron beam is It becomes a blanking state. Conversely, the blanking voltage applied to the blanking electrode 28 for the ion beam is zero, and the ion beam passes through the opening of the aperture plate 29 without being deflected and enters the deflection prism 20. At this time, the deflection prism 20 is
The voltage is off, and the ion beam travels straight without being deflected by the deflection prism 20, toward the objective lens 6 and the target 7. At this time, a scanning signal for scanning the ion beam is supplied to the electrostatic deflection plate 23 as shown in FIGS. 2(b) and 2(f), and on the cathode ray tube screen shown in FIG. The ion beam is scanned from left to right in the figure.

Next, during the second scanning period T2 in the X direction in the cathode ray tube with a retrace period [in between], the blanking voltage t! of the electron beam is t! ! i! The voltage applied to the electron beam 25 is set to zero, and the electron beam passes through the opening of the aperture plate 26 without being deflected and enters the deflection prism 20. At this time, a +V voltage is applied to the ion beam blanking electrode 28, and the ion beam is deflected and collides with the aperture plate 29, resulting in the ion beam blanking state. Furthermore, at this time, a deflection voltage is applied to the deflection prism 20, and the electron beam that has passed straight through the aperture of the aperture plate 26 is oriented in one direction and proceeds in the direction of the target 7 along the optical axis O. On the other hand, the ion beam is bent by the deflection prism 20,
The light collides with the aperture plate 22 and irradiation of the target 7 is blocked. During the period T2 during which the electron beam is irradiated on the target 7, a scanning signal is supplied so that the electron beam scans the cathode ray tube screen from Shonin to the right, but the intensity change of the scanning signal at this time is , which is the opposite of the ion beam scanning period (, TI), and is a signal in which the voltage becomes low. This is because electrons and ions have opposite charges, and as a result, the same area of the target can be scanned by the ion beam and the electron beam.

Next, during the third scanning period T3 in the X direction in the cathode ray tube after the retrace period, the ion beam is irradiated onto the target 7 in exactly the same way as period T1, and during the next fourth scanning period T4. , the target 7 is irradiated with the electron beam in the same manner as in the period T2. As a result, as shown in FIG. 3, the ion beam and electron beam are alternately scanned in the X direction, and the position of the scan in the Y direction is gradually changed. Therefore, the desired area is alternately scanned by the ion beam and the electron beam, and as far as the human eye can see, the same effect as simultaneous irradiation with the ion beam and electron beam can be obtained. As a result, for example, the surface of a desired region can be observed while being etched with an ion beam. In addition, by appropriately changing the ion beam scanning signal and the electron beam scanning signal, the surface condition can be observed by scanning a relatively wide area with the electron beam, and the ion beam can be irradiated only on a specific part of the area. It is also possible to correct IC pattern defects.

In this embodiment, the electron beam and ion beam are switched for each scan in the X direction, but the target is irradiated by switching between the electron beam and the ion beam for each frame scan. It's okay. Also, electron gun 1
Although blanking electrodes are provided for blanking the electron beam from the ion beam and the ion beam from the ion gun 2, the deflection prism 20 alone may be used to blank either one of the beams.

Here, when the target 7 is irradiated with the ion beam,
The yield of secondary electrons is 1 or more, and in the range of accelerating voltages of several kV or more, this yield increases almost in proportion to the increase in accelerating voltage. For example, if this yield is 10, irradiation with a 100 pA ion beam will yield 100
A secondary electron of 0 pA is generated, and from the position of the target irradiated with the ion beam, it is substantially 11.00 pA.
electrons have leaked out, and the target is positively charged up.

On the other hand, regarding electron beams, at an accelerating voltage of about 30 kV, the yield is 0. 1 or less, and in the case of an electron beam with a current of 100 pA, which is the same as the ion beam, 10 p
Only secondary electrons of A are generated.

Therefore, at the electron beam irradiation position, substantially 90p
A current will flow in, resulting in a negative charge-up.

In an actual device, when a Schottky emitter is used as an electron gun, a beam current approximately 10 times that of an ion beam is obtained, so it is calculated that a charge equivalent to 1100 pA - 900 pA - 200 pA flows out from the target. Therefore, by considering the ratio of the ion beam irradiation time Ti to the electron beam irradiation time Te, it is possible to reduce the outflow of the target charge to zero and prevent target charge-up. be able to.

Now, assuming that the ion beam current is It and the m beam current is Ie, the conditions for making the outflow of charge from the target and the inflow of charge into the target zero are as follows.

Ti (I i+10ψIt) -Te (le-1e/10) 11 lives 1i-Ti-0,9・1e-TeI 1=1cl
If Ie, then: 11 ·Ti-9φTe Therefore, by setting Ti:Te-9:11, charge-up of the target can be prevented.

FIG. 4 shows a blanking signal for controlling the ratio of irradiation time between the electron beam and the ion beam. Figure 4(a) is the X-direction scanning signal of the cathode ray tube, Figure 4(b)
is the blanking signal of the electron beam, and FIG. 4(C) is the blanking signal of the ion beam. In the example shown in FIG. 4, the ion beam blanking time is increased to control the ratio of the ion beam and electron beam irradiation times.

Instead of the ion beam blanking signal shown in FIG. 4(C), the ion beam blanking signal may be controlled to shorten the ion beam irradiation time as shown in FIG. 4(d). Furthermore, as shown in FIG. 5, it is also possible to replace part of the ion beam scanning period with an electron beam scanning signal. In FIG. 5, (a) is the X-direction scanning signal of the cathode ray tube, (b) is the blanking signal of the electron beam, and (C) is the blanking signal of the ion beam.

(Effects of the Invention) As explained above, in the invention of claim 1, the ion beam and electron beam are switched at high speed to irradiate the target. A similar effect can be obtained by irradiation. In addition, since the target is irradiated by switching between the ion beam and the electron beam, it is easy to align the axes of both beams, and the scanning signal of each beam can be adjusted independently. can be applied independently to desired areas.

In the second aspect of the invention, since the irradiation time of the electron beam and the ion beam to the target is controlled, charge-up of the target can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a charged particle beam composite device which is an embodiment of the present invention, FIG. 2 is a signal waveform diagram used to explain the operation of the device in FIG. 1, and FIG. Figure 3 is a diagram showing scanning on a cathode ray tube screen, Figures 4 and 5 are signal waveform diagrams in an embodiment that controls the irradiation time of electron beams and ion beams, and Figure 6 is a diagram showing the scanning of electron beams and ion beams. It is a figure showing an example of the device which performs simultaneous irradiation. ]... Electron gun 2... Ion gun 3.4 Focusing lens 5... Electromagnetic deflector 6... Objective lens
7... Target 11... Electrostatic lens 12.
... Electromagnetic lens 13 ... Deflector 14 ... Electrostatic deflection plate 15 ... Deflection coil 16 ... Secondary electron detector 20 ... Deflection prism 21 ... Power supply 22 ...
...Aperture plate 23...Electrostatic deflection plate 24.27.
...Blanking power supply 2528...Blanking electrode 2629...Aperture plate 30...Control device 31...Amplifier 32...Amplifier 33...Cathode ray tube

Claims (2)

[Claims] (1) An ion beam generation source, an electron beam generation source, a means for guiding the ion beam and the electron beam on the same optical axis, and a switch for rapidly switching between the ion beam and the electron beam and guiding them to the target. means, a lens for focusing the electron beam and the ion beam to be irradiated onto the target, and a lens for focusing the ion beam and the electron beam on the target.
and deflection means for dimensional scanning. (2) An ion beam generation source, an electron beam generation source, means for guiding the ion beam and electron beam on the same optical axis, and switching for rapidly switching between the ion beam and the electron beam and guiding them to the target. a lens for focusing the electron beam and the ion beam to be irradiated on the target; a deflection means for two-dimensionally scanning the ion beam and the electron beam on the target; and a target for the electron beam and the ion beam. A charged particle beam composite device comprising: a control means for controlling irradiation time to a charged particle beam;