JPH0266845A - Focused ion beam device - Google Patents

Abstract

PURPOSE:To eliminate tailing of ion beams by composing with an upper stage and a lower stage deflecting electrodes, and retarding the application of the blanking voltage to the lower stage deflecting electrode from that to the upper stage deflecting electrode. CONSTITUTION:The signal from a blanking signal generator 16 is amplified and applied to a blanking electrode 12 at the upper stage, and ion beams are blanked. In this case, since the ion beams are fed to a blanking electrode 13 delaying a specific time through a delay circuit 18, the signal is not fed to the electrode 13 when it is fed to the electrode 12. As a result, the beams passing through the electrode 12 advance straightly without being deflected by the electrode 13. And when the beams deflected by the electrode 12 reach the electrode 13, the beams are deflected further. Consequently, no tailing of the ion beams is generated on the target.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a focused ion beam device that irradiates a target laser 1 with a narrowly focused ion beam, and in particular,
The present invention relates to a focused ion beam device suitable for use in maskless ion implantation.

(Prior art) Boron (B), beryllium (Be), silicon <S i >, phosphorus (P), zinc (
7n) etc. are obtained. By implanting these ions into a silicon wafer or a wafer made of an If-V group element, impurities that become P-type or N-type can be obtained for these wafers. Therefore, a focused ion beam device using this ion source is
This method is attracting attention because it enables maskless impurity implantation. This liquid metal ion source has a high melting point,
Alternatively, since it is difficult to obtain ions from substances with high vapor pressure, a eutectic alloy is used to lower the melting point.

For example, when it is desired to obtain ions of Si fy Be, a ternary alloy of gold (Au), Sl, and Be is used.

The melting point of this alloy is quite low at about 350°, thus making it possible to obtain ions of each substance.

When this alloy is ionized, ions of a plurality of elements constituting this alloy are obtained, and an FXB filter is used to obtain specific ions necessary.

In writing using this ion beam, the ion beam irradiation to the target is performed while being turned on and off, and for this reason, a blanking unit is used. FIG. 5 shows conventional blanking units 1 to 1, and numerals 1 and 2 in the figure are blanking electrodes. A blanking voltage is applied to the blanking electrodes 1 and 2, whereby the ion beam TB is deflected as shown by the dotted line in the figure, collides with the blanking aperture plate 3, and hits the target beams 1 to 4 of the ion beam IB. irradiation is -10-. This blanking electrode 1.2 is normally placed at the crossover position wC of the ion beam TB.

(Problem to be Solved by the Invention) However, in the blanking described above, the ion beam enters the electrode potential at a certain speed, and immediately after the voltage is applied to the blanking electrode 1.2, The ion beams passing through point 8 and point b shown in FIG. 6, which is an enlarged view of FIG. 5, travel in trajectories Δ and B, respectively, because the distances at which they receive electrostatic force are different. The ion beam that has passed through the orbits of A and B traces a tail-like trajectory at the target "2" (this phenomenon is called tailing).

The present invention has been made in view of these points, and
The purpose is to realize a focused ion beam device that can perform ion beam blanking with almost no tilling phenomenon.

(Means for Solving the Problem) A focused ion beam device according to claim 1 based on the present invention includes an ion source, a focusing lens that focuses an accelerated ion beam generated from the ion source on a target, and In the focused ion beam apparatus, the blanking means is comprised of two stages of deflection electrodes, an upper stage and a lower stage, and
It is characterized in that the application of the blanking voltage to the lower deflection electrode is delayed from the application of the blanking voltage to the upper deflection electrode.

A focused ion beam device according to claim 2 based on the present invention includes an ion source that generates an ion beam of a plurality of ion types, a filter that selects the ion type of the ion beam to be irradiated to the target laser 1, and an ion beam generated from the ion source. In a focused ion beam device equipped with a focusing lens that focuses an accelerated ion beam onto a target and a blanking means for closing irradiation of the ion beam to the target, the blanking means may be arranged in an upper stage and a lower stage. Consisting of rows of deflection electrodes, the application of the blanking voltage to the lower row deflection electrode is delayed from the application of the blanking voltage to the upper row deflection electrode, and this delay time can be varied depending on the selected ion species. It is characterized by being configured as follows.

(Function) In the invention of claim 1, the blanking electrode has a two-stage configuration, and the timing of voltage application to the upper and lower electrodes is shifted to produce a tilling phenomenon. It has a two-stage configuration, and the timing of voltage application to the upper and lower electrodes is staggered, and the timing of voltage application is adjusted according to the ion species selected by the filter to prevent the tilling phenomenon (Example): , embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an ion beam apparatus based on the present invention, and 11 is an F for selecting ion species of the ion beam.
This is an XB filter, and a pair of blanking electrodes t12 and 13 are arranged at the upper and lower stages of the XS filter 11, respectively.

In the EXB filter 11, predetermined currents and voltages are supplied from a magnetic field generating power source 14 and an electric field generating power source 15 to the excitation coil and electrodes of the F×B filter.

A blanking signal generator 1 is connected to the blanking electrode 12.
A blanking signal is applied from the blanking signal generator 1 to the blanking electrode 13 via the amplifier 1γ.
The blanking signal from 6 is sent to the delay circuit 18. It is applied via an amplifier 19.

The operation of this J:Una configuration is as follows. When blanking the ion beam, a blanking signal is generated from the blanking generator 1G. When the blanking signal is generated, this signal is amplified and applied to the upper blanking electrode 12, and as a result , the ion beam is deflected as shown by the dotted line in FIG. 2, which is an enlarged view of the blanking electrode portion, and the ion beam is blanked. When the signal is supplied to the blanking electrode 12, the signal is not yet supplied to the blanking electrode 13. Therefore, the part of the blanking electrode 12 is connected to this electrode. The ion beam that has passed just before the signal is supplied is not deflected by the blanking electrode 13 and travels straight.When the ion beam that has been deflected by the blanking electrode 12 reaches the position of the blanking electrode 13, A blanking signal is also supplied to the blanking electrode 13, and the ion beam is further deflected as shown by the dotted line in the figure.In this case, the center of deflection of the ion beam is virtually -
"The two-stage blanking electrode 12 and the lower-stage blanking electrode If! The cross-over point C of the ion beam is located midway between the ion beam and 13. As a result, in the blanking of the ion beam according to the present invention, the tilling phenomenon of the ion beam on the target array 1 does not occur.

In the example shown in FIG. 1 above, the case where the ion species is fixed is 8=, but when the ion species is changed by the EXB filter 11, the speed of the ion beam differs depending on the ion species, and a single delay time If the ion beam is set, a tilling phenomenon of the ion beam will occur when the ion species is changed.

FIG. 3 shows another embodiment of the present invention that takes this point into consideration, and the same parts as in FIG. 1 are given the same numbers.

, the delay circuit 18 is controlled by a control circuit 20, and the control circuit 20 includes a magnetic field power supply 14 of the EXB filter 11.
．． A signal corresponding to the magnetic field strength and electric field strength of the ExB filter is supplied from the electric field power source 15, and a signal corresponding to the accelerating voltage is further supplied from the ion beam acceleration power source 21.

The control circuit 20 controls the delay time of the signal in the delay circuit 18 according to the strength of the magnetic field of the EXB filter, the strength of the electric field, and the acceleration voltage of the ion beam.

Here, the velocity V of the ion beam is expressed as follows, ignoring the relativistic correction and assuming that the acceleration voltage is V1 and the mass of the ion is m.

v=f] “Hyakushu r7Eπ For example, the velocity VS of the 3i and Be ion beams.

vb is when the accelerating voltage of the ion beam is 100 kV,
It will look like this: Note that ms is the mass of 3i, and mb is the mass of 3e.
is the mass of

T1 m5=28X1.67xlo (kq)2 mb =sxi, 67xlO(k(J)e=1.6x1
0” (c) VS =8.3X105m
/sec b = 1.5x106 m/sec Now, as shown in Fig. 4, the dimensions of the blanking electrode are 1Qmm in length along the optical axis of the electrode, 1mm in distance between the opposing electrodes, and Electrode 12 and lower electrode 1
The distance *1 between the centers of both electrodes 3 and 3 is (36 mm). Electrode 1
At the moment when the blanking voltage is applied to the electrode 2, the ion beam passing through the electrode 12 is not blanked by the electrode 13. Therefore, for an ion beam of $1, the signal delay time τS in the delay circuit 18 is
The time it takes for the ion beam passing through the electrode 13 to completely pass through the electrode 13 is as follows.

τS = 1 oox 10-3/8.3x 105-
1.2X10-7sec = 120nsec Also, for the Be ion beam, the delay time τb is
It becomes 67 nsec.

Assuming that ion species are selected using an EXB filter, the ion beam selection conditions (relationship between electric field and magnetic field)
is uniquely determined by the following Lorentz equation.

In the L equation, q is the number of selected ion cylinders. For example, for 81 ions at an accelerating voltage of 200 kV, the relationship between the electric field and the magnetic field is as follows.

En (kV/cm) -1,17XBn(k (
3auss> Conversely, if Eo and Bo are obtained, (
q/m) can be calculated backwards, and therefore the ion species can be recognized. The velocity of the ions can be obtained based on this coalescence and acceleration voltage, and the ideal delay time can be obtained depending on this velocity and the selected ion species. The control circuit 20 in FIG. 3 is based on this principle, and the control circuit 20 in FIG. A delay time corresponding to the ion beam of the selected ion species is calculated based on the signal from the electric field power supply 15 and the signal corresponding to the acceleration voltage. The control circuit 20 controls the delay circuit 18 so that the blanking signal is supplied to the lower blanking electrode 13 at the calculated delay time. This delay circuit 18
This control can be performed, for example, by switching the number of connected stages of the plurality of TTL buffer amplifiers forming the delay circuit using a relay or the like.

In this way, when changing the ion species of the ion beam irradiated to the target using the EXB filter 11,
The delay time of the signal in the delay circuit 18 is automatically controlled by the control circuit 20, and the delay time is determined according to the ion type, so no tilling phenomenon occurs during blanking, regardless of the ion type. . Note that this delay time can also be changed by changing the acceleration voltage.

(Effects of the Invention) As explained below, in the inventions of claims 1 and 2, since the timing of the blanking signal applied to the upper and lower blanking electrodes is changed, tilling of the ion beam can be prevented. It can be almost eliminated.

Further, in the invention of claim 2, since the timing of the blanking signal applied to the upper and lower blanking electrodes is changed depending on the ion species selected by the EXB filter, it is possible to determine which ion species are used. However, it is possible to eliminate tilling of the ion beam.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the main parts of an ion beam device which is an embodiment of the present invention, FIG. 2 is a diagram showing the blanking situation in the device of FIG. 1, and FIG. FIG. 4 is a diagram showing the main parts of the ion beam device according to the preferred embodiment of the invention; FIG. 4 is a diagram showing the dimensions of each component of the embodiment of FIG. 3;
Fig. 5 is a diagram showing a conventional blanking unit, and Fig. 6 is a diagram showing a conventional blanking unit.
The figure is an enlarged view of Fig. 5'0 1.2...Blanking electrode 3...Blanking aperture 11...EXB filter 12.13...Blanking electrode 14...Magnetic field generation Power supply for 15 Electric field generation power supply 16.
...Blanking signal generator 17...Amplifier 18...Delay circuit 19...
...Amplifier 20...Control circuit 21...Acceleration power supply patent applicant Japan Electronics Co., Ltd.
Ceremony for the meeting Patent attorney Fuji Ijima 1 person

Claims (2)

[Claims] (1) A focused ion beam device that includes an ion source, a focusing lens that focuses an accelerated ion beam generated from the ion source onto a target, and a blanking device that prevents the ion beam from irradiating the target. In,
A focused ion system characterized in that the blanking means comprises two stages of deflection electrodes, an upper stage and a lower stage, and the application of a blanking voltage to the lower stage deflection electrode is delayed from the application of the blanking voltage to the upper stage deflection electrode. Beam device. (2) An ion source that generates an ion beam of multiple ion types, a filter that selects the ion type of the ion beam to be irradiated to the target, and a focusing device that focuses the accelerated ion beam generated from the ion source onto the target. In a focused ion beam device equipped with a lens and a blanking means for preventing the ion beam from irradiating the target, the blanking means is composed of two stages of deflection electrodes, an upper stage and a lower stage, and the blanking means is composed of two stages of deflection electrodes, an upper stage and a lower stage. A focused ion beam device characterized in that the application of the blanking voltage to the upper deflection electrode is delayed from the application of the blanking voltage to the upper deflection electrode, and the delay time can be changed depending on the ion species selected. .