JPS62172650A - Focusing ion beam device - Google Patents

Abstract

PURPOSE:To convert magnifications of a condenser lens and an object lens at will, by furnishing two stages of the upper and the lower mass separators, and setting the filter intensities of the mass separators as required by converting the voltage and the current of the upper and the lower mass separators. CONSTITUTION:When a same intensity of electric and magnetic fields are imposed to the two stages of the upper and the lower mass separators 8 and 8', an imaginary dispersion center a comes to the central positions of the separators 8 and 8'. In this case, the filter intensities of the upper and the lower separators 8 and 8' are converted by adjusting variable adjusting resistors 22, 22' and 23, 23'. as a result, the imaginary dispersion center a moves upward or downward. When the filter intensity of the separator 8' is made higher than that of the separator 8, the imaginary dispersion center a moves upward, and vice versa. Therefore, in the condition of furnishing the separators, the magnifications of the condenser lens and an object lens can be converted as required.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Valve!F) The present invention relates to a focused ion beam device, and more particularly to a focused ion beam device in which a trade-a separator is improved.

(Prior art) A focused ion beam device ionizes atoms, extracts them to form a beam, and irradiates a material with the ion beam to change the shape and properties of the material, or to generate secondary ions generated from the material. This is a device that attempts to analyze a substance by measuring its mass number. FIG. 4 is a diagram showing an example of the configuration of a conventional focused ion beam device. In the figure, 1 is an accelerating voltage generation circuit that generates high voltage for accelerating the ion beam, 2 is an ion source that emits ions, 3 is an extraction electrode that extracts the ions emitted from the ion source 2, and 4 is the extraction electrode 3. This is a power source for applying a draw voltage that provides a potential.

For example, the output voltage of the accelerating voltage generation circuit 1 is 200K.
For example, about 5 KV is used as the supply voltage of the power source 4 for applying the extraction voltage. 5 is a multi-stage acceleration tube that accelerates the ion beam passing through the tube, and 6 is a voltage divider that applies multi-stage accelerating voltages to the multi-stage acceleration tube 5. As the voltage divider 6, for example, a high voltage dividing resistor is used. 7 is a condenser lens (also called a focusing lens) that is composed of an electrostatic lens and focuses the ion beam;
8 is an EXB mass separator (hereinafter referred to as jiff) that separates ions of different quality among the passing ions.
i separator).

The quality separator 8 applies a magnetic field and an electric field orthogonal to the magnetic field to passing ions to remove unnecessary ions. In other words, by taking advantage of the fact that the trajectory of ions passing through a magnetic field is greatly bent in order of ions starting with the smallest mass and mass, and by applying an electric field perpendicular to the magnetic field to make the necessary ion beams travel straight, unnecessary ions are removed. It is something to do.

Reference numeral 9 represents an objective lens for focusing the ion beam which is constituted by an electrostatic lens like the condenser lens 7, 10 represents a deflector for scanning the ion beam in the X and Y directions, and 11 represents a sample to be irradiated with the ion beam. Reference numeral 12 denotes a voltage divider to which the output voltage of the accelerating voltage generation circuit 1 is applied, and like the voltage divider 6, for example, a high voltage dividing resistor is used. The voltage divider 12 is provided with taps A and 8 as shown in the figure, and the divided voltage at the taps is applied to the objective lens 9, and the divided voltage at tap B is applied to the condenser lens 7, respectively. The operation of the device configured as described above will be explained as follows.

The ion beam generated by the ion source 2 and passed through the opening of the extraction electrode 3 is accelerated by the multistage acceleration tube 5. The high-speed ion beam that has passed through the multi-stage acceleration tube 5 and has been accelerated is focused by a condenser lens 7, unnecessary ions are removed by a mass separator 8, focused again by an objective lens 9, and then deflected in a predetermined direction by a deflector 10. The sample 11 is irradiated after being deflected. As a result, ion implantation or sputtering with an ion beam is performed on the surface of the sample 11, or secondary ions are ejected.

FIG. 5 is a diagram showing the trajectory of the ion beam formed in this manner until the sample 11 is irradiated. The numbers in the figure correspond to the numbers of the components in FIG. For example, when the applied voltage is 200 KV, the voltage of the condenser lens 7 is 50 KV, and the voltage of the objective lens 9 is 100 KV.
It is about KV. As mentioned above, the focused ion beam device is composed of two stages of lenses, that is, the condenser lens 7 and the objective lens 9. As is clear from the ion beam trajectory diagram in FIG. A mass separator 8 is placed at the crossover position.

The reason why it is necessary to create a crossover at the center of the mass separator 8 is as follows. The ion source used in focused ion beam devices is generally a liquid metal ion source, and the ions obtained from this ion source have a voltage of 10 eV under normal usage conditions.
It has a certain energy range. Also, the pawn portion is 1lIl.
Since the filter is an energy filter, if a beam with such an energy width is selected, the selected beam will also cause dispersion. In FIG. 6, the center of dispersion of the selected beam is at point a in the figure, and does not depend on the intensity of the quality a ms filter 8a. 8b in the figure is the mass separator aperture (
gap>. 8a and 8b constitute a mass separator 8. Therefore, if the object point of the lens (objective lens 9) below the mass separator 8 is brought to the center of this dispersion, there is virtually one object point, and the dispersion on the sample 11 disappears.

(Problem that J1 Ming is trying to solve) As mentioned above, the mass separator 8 is placed at the crossover position, but since the position of the mass separator 8 is fixed, the crossover of the ion beam by the condenser lens 7 is The positions do not change, and although it is a two-stage focusing system, the operating conditions of the condenser lens 7 and objective lens 9 are fixed and cannot be set to arbitrary values. If there is no mass separator, by controlling the operating states of the condenser lens 7 and objective lens 9, it is possible to move the O swarm and change the probe current and probe diameter to the desired values.

A method to eliminate the above restrictions and also install a mass separator is Q: F! There is a method of mechanically moving the device. However, such a method makes the apparatus complicated and expensive.

The present invention has been made in view of these points, and
The purpose of this is to create a focused ion beam device that can perform crossover of the ion beam using the condenser lens 7 while attaching a quality separator, and can therefore move the object point of the objective lens 9 to arbitrarily change the magnification of both lenses. It is about making it happen.

(Means for Solving the Problems) The present invention, which solves the above problems, focuses an ion beam emitted from an ion source with a two-stage lens system consisting of a condenser lens and an objective lens, and irradiates it onto a sample. In a focused ion beam device, two stages of upper and lower mass separators are provided between a condenser lens and an objective lens, and the current and voltage applied to these mass separators are varied, and the filter strength of the mass separator can be adjusted arbitrarily. It is characterized by being configurable.

(Function) The present invention provides two stages of upper and lower mass separators between the two lenses, and changes the voltage and 1f flow value of the upper and lower mass separators, and arbitrarily sets the filter strength of the mass separators. do.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of main parts showing an embodiment of the present invention. Other parts are assumed to be the same as the conventional configuration. As shown in the figure, mass separators 8 and 8' are provided in two stages, upper and lower, and each mass separator is equipped with a high voltage power source and a current source for operating the mass separators. These power supplies are linked together and can each have arbitrary values. 8 is an upper stage mass separator, 8' is a lower stage mass separator, 20 is an upper stage current amplifier, 20' is a lower stage current amplifier, 21 is an upper stage, and 21' is a lower stage voltage amplifier.

The current amplifier 20.20' controls the magnetic field of the mass separator (1rf1 field control), and the voltage amplifier 21.21' controls the electric field of the mass separator (electric field control).

22 and 23 are variable resistors on the upper stage, and 22' and 23' are variable resistors for adjusting voltage and current, respectively, on the lower stage.

In the circuit configured in this way, the quality of the upper and lower two stages is 111i! When electric and magnetic fields of the same strength are applied to 18.8', the virtual dispersion center a will be located at the center of the two mass separators 8.8', as shown in FIG. Here, the variable resistor 22 for adjusting the filter strength of the mass separator 8.8' in FIG.
．． When 22' and 23.23' are adjusted so that the upper tool is used, the virtual dispersion center a moves downward or upward as shown in FIGS. 3(a) and 3(b). Lower mass separator 8'
When the filter strength of the upper stage mass separator 8 is made stronger than the filter strength of the upper stage mass separator 8, the virtual dispersion center a moves downward as shown in Fig. 3(a), and the filter strength of the upper stage mass separator 8 is made stronger than the filter strength of the lower stage mass separator 8. If the filter strength is made stronger than the filter strength of the filter 8', the
As shown in b), the virtual dispersion center a moves upward. The movement distance of this virtual center a is between the center of the upper mass separator 8 and the center of the lower mass separator 15i8'.

Therefore, the magnifications of the condenser lens 7 and the objective lens 9 can be changed arbitrarily by creating an ion beam flux O over by the condenser lens 7 at this moving virtual dispersion center a, and by making that point the object point of the objective lens 9. can be done. Whether or not this virtual center of dispersion coincides with the crossover position can be confirmed by adding a WOBBLER signal. In other words, by adding a sine wave of an electric field (or magnetic field) with the same intensity ratio as the intensity ratio of the upper and lower am separators 8.8' to the upper and lower 11fiPJ8.8', the probe position will not move on the sample 11 surface. Natsut: However, this is the point where the virtual dispersion center and the O-sovere position match.

'fFi flow given to upper and lower mass fraction lIl device 8.8'.

A circuit is provided that can control the intensity of the voltage to an arbitrary ratio. This is, for example, the variable resistor 22 in FIG.
23, when the current and 1R pressure increase, 22', 23
' If you link them so that they move in the opposite direction so that the current and voltage decrease, you can arbitrarily choose the intensity ratio.

(Effects of the Invention) As described above in detail, according to the present invention, the mass separator is configured in two stages, upper and lower, and the virtual fractional center of the ion beam can be moved between them, so that the ion beam is separated by a condenser lens. By matching the crossover position, the magnification of the condenser lens and objective lens can be changed with the 1iffi separator provided. Therefore, it becomes possible to arbitrarily control the probe diameter of the ion beam, the flow of the probe 11, etc.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the main part of an embodiment of the present invention, Fig. 2 is a diagram showing the position of the crossover when the filter strengths of the two-stage mass separators are made equal, and Fig. 3 is a diagram showing the position of the crossover when the filter strengths of the two-stage mass separators are equal. A diagram showing the position of the crossover when the strength of the mass separator is changed; FIG. 4 is a schematic configuration diagram of a conventional focused ion beam device;
FIG. 5 is a diagram showing the trajectory of the ion beam, and FIG. 6 is a diagram showing the beam dispersion occurring in the mass separator. 2...Ion source 3...Extraction electrode 4...
Power supply 5... Accelerator tube 6.12... Voltage divider 7... Condenser lens 8.8'... Mass separator (EXB) 9... Objective lens 10... Deflector 11...
Sample 13...Aperture 20.20. '...Current amplifier 21.21'...Voltage amplifier 22.22', 23.23'...Variable resistor Patent applicant: JEOL Co., Ltd. Agent: Patent attorney: Fuji Ijima (1 person) Figure 1 Fig. 2 8, skin mass infantile O; A moxibustion dispersion center Fig. 3 (A) (B) O; tongue decoy A projection center Fig. 4 9; objective lens 10; deflector 11, sample No. 5 Figure 91 Objective lens 10r Direction device Figure 6 λ Oi11 Separator Mass filter Bbi Snow 4 Separator Apertise 9, Objective lens

Claims (1)

[Claims] In a focused ion beam device in which the ion beam emitted from the ion source is focused by a two-stage lens system consisting of a condenser lens and an objective lens and irradiated onto a sample, there are two mass separators, upper and lower, between the condenser lens and the objective lens. What is claimed is: 1. A focused ion beam device, characterized in that it is configured to vary the current and voltage applied to these mass separators, and to make it possible to arbitrarily set the filter strength of the mass separators.