JPH012786A - Ion beam processing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ion beam processing machine, and more specifically, an ion beam processing machine that performs ion implantation or ion beam processing, and is particularly equipped with a blank separation means. The present invention relates to an ion beam processing machine.

[Conventional technology]

FIG. 9 shows a conventional ion beam processing machine, in which an ion beam (2) emitted from a high-brightness ion source (1) such as a liquid metal ion source is sent to a first focusing lens.

lenses (3), bluffing device (4), mass separator (5)
), separation aperture (6), second focusing lens (7) and deflector (reaches the sample (9) through the ion source (1)
) ion beam emitted from (2) +! i 1 is focused at the center of the mass separator (5) by the ion beam (3), and the crossover (lo) is the focal point of the ion beam.
is formed. The light is further reduced by a second focusing lens (7) and irradiated onto the sample (9). The ion beam (2) irradiated onto the sample (9) is injected into the sample (9) or sputters the sample (9).

The mass separator (5) plays the role of selecting a desired ion species from several types of ion species having different mass numbers (m/e) that form the ion beam (2). For example, Au-8
When a eutectic alloy called i is used, Au'', Si
+, Au", Si2+, etc. are released, so it plays the role of extracting only Au+ or Si+ from these ion species. Also, when using a single metal such as Ga, it Used to separate bodies.

Next, the configuration of the mass separator (5) is shown in FIG.

This mass separator (5) is called a gXB mass filter, and the desired ion species travel straight through.

(Lla), (llb) are pole pieces, (12a),
(12b) is the E electrode. Now, the magnetic field B0(x
direction) and an electric field E0 (y direction). The force acting on a charged particle (quality ffim) traveling straight on the central axis (two axes) is given by the following equation.

m meal = 0 ...... (1) my = q (Eo
-2Bo)...! ...(2) mz=qyBo ・
...From equations (3) and (2), z = Eo/Bo
Charged particles that satisfy the condition travel straight ahead, and particles that do not meet this condition are filtered out by the separation aperture (6). In FIG. 10, (2) shows the total ion beam before mass separation, (13) shows the ion beam that satisfies the above straight forward condition, and (14) shows the filtered ion beam. The reason why the crossover (10) is located at the center of the mass separator (5) is to make astigmatic dispersion that occurs after passing through the mass separator appear to be zero due to the energy dispersion of the ion source. It is.

Since this invention relates to blanking in an ion beam processing machine equipped with this EXB mass filter, the general theory of blanking will be described before explaining a conventional blanking device.

In FIG. 9, (4) is the most common blanking device, and its structure is shown in FIG. 11. (lSa).

(1sb) is a blanking electrode placed parallel to the axis of the ion beam (2), (tsd) and (tab) are blanking power supplies.

If no voltage is generated in the blanking power supplies (16a) and (tab), the beam (2) will travel straight, so if the beam (2) is in the ON state, if a voltage is generated, the beam (2) will move straight. As if it were a blanking electrode (4sa),
Since the beam is deflected as if bent at the center of (tab), it is filtered and a beam OFF state is created. At this time, the required blanking voltage (
VB) takes dimensions A, B, C, and D as shown in the diagram, and then
It is given by the following formula.

As can be seen from this equation, in order to reduce ■, it is sufficient to increase the dimension iA. By the way, when switching ON/OFF in a blanking device, the positional fluctuation of the beam on the sample often becomes a problem.

Figure 12 shows this situation. In the figure, ↓ is the center of the blanking electrode, 0 is the position of the crossover (10), <0
．． indicates the position of the sample (9), the solid line indicates the beam trajectory on the beam trajectory axis, and the dotted line indicates the beam trajectory at the time of switching. When blanking is applied, the beam bends from the point indicated by ↓, so the crossover (10) moves away from the central axis. Therefore, the imaging point of the crossover (lO) moves to a point away from the central axis, as shown in FIG. 2(a). However, this phenomenon is not observed when the position of the crossover (lO) and the center of blanking coincide. The reason for this is shown in the same figure (bl
This is because the crossover (ro) always exists on the central axis even if blanking is hidden, as shown in FIG. Therefore, in order to prevent the beam position from changing, it is necessary to match the position of the crossover (lO) with the center of blanking.

Therefore, a conventional blanking device that can match the crossover position and the center of blanking is used as the first method.
Figure 3 will be explained. In Figure 13, (15a
) ~ (tsd) is the pole piece (ha).

This is a blanking electrode consisting of two sets of parallel flat plates provided before and after (llb). In the figure, only the beam trajectory when the beam is OFF is shown. Since this device is deflected twice, it follows a trajectory as shown by the solid line in the figure.

This trajectory can be virtually considered to be equivalent to a trajectory deflected only once at the center of the pole pieces (1ta) and (ttb), as indicated by a, tJ. Therefore, according to this device, blanking can be performed without causing a change in the beam position.

However, this device has many components, so we had to manufacture it.

Adjustment (alignment) is complicated. Furthermore, the first lens (3
) to the separation aperture (6) is restricted, so the lengths of the blanking electrodes (lSa) to (15d) are also restricted. Therefore, the blanking voltage (vB)
For example, 100 to 200v
degree is necessary. Therefore, the time required to generate or eliminate the voltage is, for example, 200 m5, making it difficult to apply it to an ion beam processing machine that requires extremely high-speed blanking.

Furthermore, since a high voltage semiconductor such as a FET must be used, the blanking power supply becomes expensive.

[Problem that the invention seeks to solve]

The conventional ion beam processing machine as described above has a blanking device configured as described above, so the configuration is complicated, making manufacturing and adjustment complicated, and the blanking voltage is high, making blanking difficult. There were problems such as the inability to cope with faster speeds.

This invention was made to solve the above-mentioned problems, and its purpose is to provide an ion beam processing machine that is easy to manufacture and adjust and is equipped with a blanking device that can handle high-speed blanking. do.

[Means for solving problems]

The ion beam processing machine according to the present invention has a means for mass-separating desired ion species using orthogonal magnetic fields and electric fields.
It also has a blanking function.

[Effect]

In this invention, the blanking power supply generates and extinguishes the blanking voltage, thereby performing the blanking function without causing any disturbance to the mass separation function.

〔Example〕

FIG. 1 shows the quality of one embodiment of this invention. 5+ A pole piece (1) made of a material with high magnetic permeability, such as pure iron, is placed perpendicularly to the Bfi poles (12a) and (12b) provided in parallel and facing each other. xta
), (ob), and a yoke (17) formed of a material with high magnetic permeability to form a magnetic path.

The pole pieces (lta) and (ttb) have coils (te).
a), (tab) It is rolled up.

The yoke (17) was made into a so-called H-type with emphasis on the symmetry of the magnetic field and mechanical strength, but as shown in Fig. 2,
A so-called C type may also be used.

Also, consider the leakage magnetic flux with the pole piece (lla).

(lxb) is shown with coils (tea) and (tab) wound around it. te
There is no difference in the effect of this invention even if a), (tab) or (step 8) is wound around.

Figure 4 shows the parts related to the E electrodes (12a) and (tzb).
Rteh F), the blanking electrode (16) is connected to the E power supply (2
0b) in series.

Further, in this embodiment, since there is no blanking electrode, there is no need for adjustment (alignment).

Next, the operation will be explained. For example, 69Ga+ and 71
Consider separating Ga+. 69 Make Ga+ go straight? The magnetic flux density (Bo) and electric field strength (Eo) required to filter out IGa+ are as follows when the accelerating voltage is 100 kV.
For example, the voltage is 8000 Gauss and 4.4 kV/cm. When such a magnetic field and electric field are applied, Fig. 4 (a
), the beam is ON, beam (13) is 69 Ga +, beam (14) is 71 Ga
Corresponds to +. In order to create the beam OFF state as shown in FIG. 6(b), a blanking voltage (VB) may be applied to the E electrode (rzb) in addition to the E voltage (-5 above-). The beam is deflected so that it is bent at the center of the E electrode.

This deflection must be performed in a direction in which the filtered out beam (14) is away from the central axis. If done in the opposite direction, the beam (14) may pass through the separation aperture (6).

Since a cross opper (10) is formed at the center of the E electrodes (tza) and (tzb), no change in the position of the beam on the sample is observed even when switching ON-OFF.

In this device, the length of the blanking electrode (A) K corresponds to the length of the E electrodes (12a) and (t2b).

This length can be increased since there is no need to provide a blanking electrode. Therefore, the blanking voltage VB is, for example, 2
0 to 30 volts is sufficient. When the voltage decreases like this, 1
For example, it is suitable for low voltage operation such as operational amplifiers and can use semiconductors with a fast slew rate, so the blanking speed can be increased. Furthermore, since there are many manufacturers that can supply such semiconductors, there are fewer restrictions when designing a power supply, and it is possible to make the power supply cheaper.

In addition, in the above embodiment, the blanking power supply (16) is
Although the one placed on the positive side of the II source is shown, it goes without saying that it is also possible to change the polarity of the blanking power supply (16) + 7) and place it on the negative side as shown in Figure 5(a). . Furthermore, the same effect can be obtained even if two blanking power supplies (16) with different polarities are used as in the fifth embodiment. In this way, the blanking voltage required for one power supply is halved, allowing for faster blanking.

Furthermore, as shown in FIGS. 5(C), (d), and (el), one end of the blanking power supply (16) may be grounded, and the E power supply may be placed on top of it.In this way,
Since all control of the blanking power supply (16) can be performed on the ground side, design of the power supply becomes easy.

In addition, as shown in FIG. 6 as another embodiment, an insulator (
19), pole piece (1ta), (ub
), the pole pieces (Ha) and (ttb) can also serve as a blanking function. In this way, since blanking is performed in the X-axis direction in FIG. 2(a), the filtered out beam will not be in the ON state.

Note that the present invention is not limited to the case where the crossover (10) is located in the middle of the mass separator. In order to minimize the magnetic and electric fields required for mass separation, although it is not possible to achieve an apparent zero energy dispersion, a crossover (10) is inserted between the separation apertures (6) as shown in FIG. It is often tied to a position. Alternatively, a method may be used in which the magnification of the first lens (3) is made infinite and no crossover is formed, as shown in FIG. Even in such a case, the present invention produces similar effects.

〔Effect of the invention〕

As described above, according to this invention, the mass separation means also has a blanking function, so the structure can be simplified, and the blanking voltage can be lowered, so the blanking speed can be increased. Additionally, it has the effect of making blanking power supplies cheaper.

[Brief explanation of drawings]

FIG. 1 shows one embodiment of the present invention, in which FIG. 1(a) is a plan view of the main part, FIG. The figure is a plan view showing the deformation of the yoke shown in Fig. 1, Figs. 3 (a) and (b) are plan views showing the deformation of the coil shown in Fig. 1, respectively, and Fig. 4 explains the operation of the one shown in Fig. 1. Is the front view of the main parts schematically shown in Figure 5 a blanking of the one in Figure 1? ! Partial wiring diagrams showing various connections of tI2@, FIGS. 6(a) and (b) are plan views and front cross-sectional views of other embodiments, and FIGS. 7 and 8 are diagrams other than those shown in FIG. 1, respectively. FIG. 3 is a front view of main parts for explaining the operation of the apparatus. Figure 9 is a schematic front view of the main parts of a conventional ion beam processing machine.
Fig. 10 is a perspective view of the main part to explain the principle of the EXB mass filter in Fig. 9, and Figs. 11 (a) and (b) are partial plane views to explain the operation of the EXB mass filter in Fig. 9. 12(a) and 12(b) are partially schematic front views for explaining the operation of the device shown in FIG. 9, and FIG. 13 is a partial front view for explaining the blanking function of the conventional device. FIG. (1)...Ion source, (3), (7)...1st. Second focusing lens (ion focusing means), (5)...mass separator (mass separation means), (lO)...crossover. (xxa), (txb), , pole piece (magnetic field generating means), (12a), (12b) --E electrode (electric field generating means'), (16)...blanking power supply, (
20a), (20b)...E power supply. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] (1) An ion source, an ion focusing means for focusing ions emitted from the ion source, and a means for mass-separating a predetermined ion species from ion species having different mass numbers using perpendicular magnetic and electric fields. Moreover, the mass separation means also has a blanking function. (2) The ion beam processing machine according to claim 1, wherein the blanking function is also performed by the electric field generating means. (3) The ion beam processing machine according to claim 1, wherein the blanking function is also performed by the magnetic field generating means. (4) The ion beam processing machine according to claim 1, wherein a focal point of the ion beam is formed at the center of the mass separating means.