JPH0234414B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a charged particle beam device that can easily switch the type of charged particle beam irradiated onto an observation sample or processing material. In charged particle beam devices such as ion microanalyzers, which are ion beam devices for microfabrication used in the manufacture of semiconductor integrated circuits, it is necessary to switch the type of ion beam to be irradiated onto the processing material or observation sample depending on the purpose. be done. In response to this requirement, with conventional apparatuses, it has been difficult to easily switch the type of irradiation ion beam by scanning in a short time while the processing material or observation sample remains fixed. The purpose of the present invention is to solve these difficulties and make it possible to switch the irradiation ion beam easily and in a short time. In an apparatus for irradiating an observation sample or a processed material through a lens and a deflection means, a filter having two magnetic pole plates for forming a magnetic field perpendicular to a plane including the Z axis, and a magnetic field of the filter and a magnetic field arranged around the filter are provided. A plurality of charged particle sources that enter charged particle beams from perpendicular directions, and the polarity and strength of the magnetic field of the filter and the strength of the two magnetic pole plates depending on the type of charged particle beam that selectively enters the filter. It is characterized by providing means for varying the potential. The drawing is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention, which includes ion sources 1A and 1B, an electron gun 1D, a filter magnetic pole plate 2, a filter slit 3, an electrostatic lens, a deflection means 5, and a processing material 6 and 2. The electronic detector 7 is housed in a container kept in vacuum. Although only one of the filter magnetic pole plates 2 is shown in the figure, it is composed of two plate-shaped magnetic bodies placed on both sides of the optical axis Z, and a current power source is connected to the excitation coil 8 attached to the outside of the magnetic pole plate 2. By supplying an excitation current from 9, a magnetic field perpendicular to the optical axis Z is formed between both magnetic pole plates. An electron gun 1D is arranged above the optical axis Z of the magnetic pole plate 2, and two ion sources 1A and 1B are arranged symmetrically with respect to the optical axis Z in a direction perpendicular to the optical axis Z and the magnetic field. The magnetic pole plate 2 and the filter aperture 3 are insulated from surrounding members, and their potential is given by the output of a DC source 10. An accelerating voltage Vc is selectively applied to each ion source 1A, 1B and electron gun 1D from a DC high voltage power supply 11, and the ion beam or electron beam accelerated by the accelerating voltage Vc passes through a filter magnetic field, Passes through filter aperture 3. The ion beam or electron beam that has passed through the filter aperture is supplied with a voltage from the lens power source 12.
The material to be processed 6 is irradiated with a focusing effect by an electrostatic lens 4 given Vl and a deflecting effect by a deflecting means 5. When performing fine processing using an ion beam, a deflection signal is supplied to the deflection means 5 in accordance with the processing pattern on the material. In addition, when observing a scanning image regarding the surface shape of the material 6, the scanning signal from the scanning signal generating circuit 13 is supplied to the deflection means 5 via the variable width device 14, and the scanning signal from the same scanning signal generating circuit 13 is A scanned image is displayed on the cathode ray tube 15 by using the output of the secondary electron detector 7 provided near the material 6 as the brightness modulation signal of the cathode ray tube 15 to which the signal is supplied. However, when processing materials such as silicon wafers by directly irradiating them with an ion beam, an ion beam of an element with a relatively high melting point such as boron (B), phosphorus (P), or arsenic (As) is required. Therefore, ion sources using liquid metals often use eutectic alloys containing these elements to lower the melting point. However, when a eutectic alloy is used, ion species other than the target ion species are also extracted as an ion beam.
It is necessary to remove unwanted ion species from the ion beam using a mass separator or mass filter. In the embodiment shown in the drawings, an ion source 1A,
1B is installed, so when a liquid metal ion source using a eutectic alloy is used as an ion source, the target ion can be obtained by adjusting the polarity (direction) and strength of the filter magnetic field. It becomes possible to guide only the seed ion beam to the filter aperture 3. Furthermore, since there is no need for the electron beam generated from the electron gun 1D to pass through a filter, the filter magnetic field is set to zero before use. Furthermore, it is also possible to provide a single element liquid metal ion source at the position of the electron gun 1D. The embodiment shown in the drawings is equipped with a central control circuit 16, which controls a signal P specifying which of the charged particle beam sources 1A, 1B, and 1D is to be used, and a signal P that specifies which of the charged particle beam sources 1A, 1B, and 1D is to be used, as well as a signal P that specifies which of the charged particle beam sources 1A, 1B, and 1D is to be used, and a signal P that specifies which of the charged particle beam sources 1A, 1B, and 1D is to be used. Based on input signals such as a signal Q specifying the specific charge of the particle beam, a signal R specifying the charge polarity of the charged particle beam, and a signal S specifying the accelerating voltage of the charged particle beam,
DC high voltage power supply 11, current power supply 9, DC power supply 1
This is to control the lens power source 12 and the variable amplifier 14 so that the charged particle beam is irradiated onto the workpiece 6 in a correctly focused state no matter which charged particle beam source is used. The following table shows the acceleration voltage Vc when taking out a certain positive polarity ion beam from the ion source 1A, when taking out a certain negative polarity ion beam from the ion source 1B, and when taking out an electron beam from the electron gun 1D,
Voltage Vf applied to magnetic pole plate 2 and lens power supply 1
This is a summary of specific examples of the values of the output Vl of No. 2.

[Table] Note that if the polarities of the ion beams taken out from the ion sources 1A and 1B are opposite to each other, the polarity of the excitation current supplied to the excitation coil 8 of the filter may be the same; When the polarities of the extracted ion beams are the same, the polarities of the currents supplied to the excitation coil 8 are set to be opposite to each other. However, the present invention is not limited to the above-described embodiments; for example, in order to increase the number of ion sources provided around the periphery of the filter, the ion source 1
A new ion source may be provided between A, 1B and the electron gun 1D. Further, the ion source is not limited to the type that uses liquid metal, and it goes without saying that a dual plasma ion source and other ion sources can be used. As described above, according to the present invention, a magnetic field type mass
By employing a filter and utilizing the dual functions of deflecting the ion beam and removing unnecessary ions, it becomes possible to switch between multiple types of ion beams and electron beams simply by controlling the device's electrical circuit. Therefore, great effects can be obtained when applied to microfabrication devices using ion beams.

[Brief explanation of drawings]

The drawing is a block diagram showing an apparatus according to an embodiment of the present invention. 1A, 1B: ion source, 1D: electron gun, 2: filter magnetic pole plate, 5: deflection means, 6: processing material,
7: Secondary electron detector, 8: Excitation coil, 9: Current power supply, 10: DC power supply, 11: DC high voltage power supply,
12: Lens power supply, 13: Scanning signal generation circuit, 1
4: Variable amplifier.

Claims (1)

[Claims] 1. In a device that irradiates a charged particle beam incident along the optical axis Z onto an observation sample or processing material through a focusing lens and a deflection means, two magnetic pole plates are installed to form a magnetic field perpendicular to the plane containing the Z axis. a plurality of charged particle sources that cause charged particle beams to be incident on the periphery of the filter from a direction perpendicular to the magnetic field of the filter; A charged particle beam device comprising means for varying the polarity and strength of the magnetic field and the potential of the two magnetic pole plates.