JPS6391945A - Ion beam device - Google Patents

Abstract

PURPOSE:To improve the beam utilization efficiency without making a mass spectrometry magnet large-sized by providing an ion beam focusing means between an ion extracting section and a mass spectrometry section. CONSTITUTION:Specific ions generated by a plasma generating section 1 are extracted by an ion extractor 2 to become an ion beam. The ion beam is focused by an electrostatic quadruple-pole lens 12 of a beam focusing means provided between the extractor 2 and a mass spectrometry section 3 and entered into the spectrometry section 3. According to this focusing, the whole quantity of the beam current can be guided between magnetic poles and the magnetic field between the magnetic poles can be kept constant without widening the magnetic pole distance of the spectrometry magnet of the spectrometry section 3 even if the beam current is increased or the beam line between the extractor 2 and the spectrometry section 3 is long. Thereby, the beam utilization efficiency can be improved without making the mass spectrometry magnet large-sized.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

This invention is used as an ion implantation WZ in a semiconductor processing process, etc., and includes a plasma generation part that turns introduced raw material gas or metal vapor into plasma, and a plasma in this plasma generation part that generates specific four properties. an ion extraction section that extracts ions with a specific NR/
an ion beam consisting of an acceleration section that gives a predetermined kinetic energy to the ions extracted by the mass spectrometry section, and the specific ions ejected from this acceleration section; The present invention relates to an ion beam device that includes a lens system that focuses the ion beam onto the surface of the sample and implants ions by irradiating the surface of the sample with an ion beam.

[Prior art and its problems]

FIG. 5 shows an example of the configuration of a conventional ion implantation device. In the figure, a plasma generating unit 1 is one that generates predetermined ions by accelerating electrons emitted from a heat sink using a TL magnetic field, causing them to collide with introduced gas molecules or metal air, and turning them into plasma. It is. An extraction electrode system 2 constituting the ion extraction section is disposed opposite to a slit provided in a plasma chamber constituting the plasma generation section 1, and a high voltage is applied between the ion extraction electrode system 2 and the plasma chamber to identify the ion from the plasma. extracts ions with the polarity of The ion beam thus obtained is broken and its trajectory is bent as shown by the dashed line in the figure by the 1Itfik analysis magnetoft 3 constituting the mass spectrometer. At this time, since the radius of curvature differs depending on the charge/matter ratio of the ions, the ions passing through the slit 4 are limited to those having a specific charge/matter ratio. The acceleration v5 constituting the acceleration unit 104 accelerates the specific ions obtained by the method described above to a predetermined kinetic energy. If the kinetic energy of the ions obtained between the plasma generating section 1 and the extraction electrode system 2 is large enough, the accelerating tube 5 may be omitted. The lens system 6 focuses the obtained ion beam onto the surface of the substrate 10 held in the implantation chamber 11 to a predetermined irradiation area. The vertical direction parallel to the paper surface is the X direction, and the direction perpendicular to the paper surface is the Y direction, and the specific ion is
The ion beam is deflected in the
While being deflected by the pole pair 7°8, the entire surface of the substrate 10 is irradiated at −(!).The reflector electrode pair 9
A high DC voltage is applied to the beam, and the beam trajectory is bent to remove neutral atoms present in the beam just before irradiating the substrate IO. In addition, as a method of uniformly irradiating the entire surface of the substrate 10 with the ion beam, instead of using the electrode pair 7, 8, a disk to which a plurality of substrates 10 are usually attached is rotated around the central axis. A machine that reciprocates in the direction of the surface of the disc! There is also a deal scanning method. In such a device, there is a limit to the electrostatic lens effect in the electrode system of the extraction section, and as the beam current increases or the beam line becomes longer, the beam diameter increases. As the beam diameter increases, the distance between the magnetic poles of the mass spectrometer magnet needs to be larger than the beam diameter, so in addition to magnets in which the magnetic field between E531-5 is provided by a permanent magnet, the magnetic field is provided by an excitation coil. Even in cases where an excitation coil is designed to have a specified rated magnetomotive force and housed in a specified space, the strength of the magnetic field is not necessarily maintained at its original size, and as a result, the bending radius of the beam increases and the magnet There was a problem that the beam usage efficiency would decrease unless the size was increased and the distance between &1 was increased.

[Purpose of the invention] SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an ion beam apparatus that can obtain high beam utilization efficiency without increasing the size of a mass spectrometry magnet. [Key points of the invention]

This invention is applicable to an electrostatic quadruple-like lens and a magnetic quadruple-like lens, which will be described later.
This method focuses on the fact that the polar lens can focus the ion beam to an arbitrary distance, and the electrostatic quadruple lens effect can be changed depending on the magnitude of the ion beam current and, therefore, the magnitude of the extraction voltage. Is the ion beam focusing means such as a lens or magnetic quadruple lens an ion extractor? 1 to focus the ion beam ejected from the ion extractor, and transfer the focused ion beam to the IT
The purpose is to achieve the above object by making the light incident on the analyzer.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention. Between the mass spectrometry section 3 and the ion extraction section 2, which is equipped with extraction electrodes arranged in multiple stages in the ion traveling direction on the front surface of the plasma generation section 1, from which ions are extracted, there are four columnar r1
F5r are arranged surrounding the ion beam in the same direction as the traveling direction of the ions, that is, the direction of the ion beam, and at equal intervals in the circumferential direction as shown in FIG. An electrostatic quadruple-like lens 12 is arranged in which a plurality of unit electrode pairs 121°, 122) 123 formed by electric current are arranged in the direction of the ion beam such that electrodes of the same polarity as the previous stage are shifted by 90'' in the circumferential direction. The ion beam entering the electrostatic quadruple-like lens 12 from the ion extraction unit 2 is first focused in the X direction by the first unit electrode pair 121 and then enters the second unit electrode pair 122. ,
Second unit 1! The light enters the third unit electrode pair 123 while being focused in the Y direction by the pole pair, and is focused in the X direction by the third unit electrode pair 123 and guided to the analysis magnet of the mass spectrometer 3. At this time, the focus of the Y-direction beam width is focused on the slit 4 of the accelerating section 104, including the convex lens effect of the electrostatic quadruple-like lens 12 on the Y-direction beam width and the concave lens effect of the analysis magnet on the Y-direction beam width. Then, the X-direction beam width is focused on the slit 4 of the accelerating section 104, including the convex lens effect of the electrostatic quadruple-like lens 12 on the X-direction beam width and the convex lens effect of the analysis magnet on the X-direction beam width. The voltage supplied to each unit electrode-to-electrode of the electrostatic quadruple-like lens is controlled as follows. The ion beam current is uniquely determined by the extraction voltage unless the extraction electrode system is changed, and the lens effect of the analysis magnet is also uniquely determined by the extraction voltage.
11'ta The voltage supplied to each unit electrode counter current (J) as a control amount for controlling the lens effect of the quadrupole lens can also be calculated from only the extraction voltage. 13 is the extraction voltage detection section, 14 is a calculation unit; 15 is a voltage control unit for controlling the output voltage of the next stage based on the calculation result of 14;
Reference numeral 16 denotes a voltage distribution section which is controlled by the voltage control section 15 at the previous stage and outputs a desired voltage to the electrodes of each unit electrode pair. The dashed line in the diagram shows the spread of the ion beam when the electrostatic quadruple-like lens 12 does not exist, and how the present invention can prevent the mass spectrometer from increasing in size with respect to this spread. It shows whether it has a significant effect. FIG. 3 shows an example of a support structure for the electrostatic quadruple-like lens 12 shown in FIG. In order to do this, the vacuum container is airtightly interposed between the insulating tube 127 and the insulating flange 126, between the insulating flange 126 and the insulating flange 125, and between the insulating flange 125 and the insulating tube 128, respectively. ) Plate-shaped rings 127a, 126a, 125a and extraction electrodes 27
, 26. The electrostatic quadruple-like lens is connected to one of the plate-shaped or cylindrical connecting conductors (here, the innermost conductor) passed between the electrostatic quadruple-like lens and the supporting insulator 124 made of synthetic resin or ceramics. Each 'C:, IFii pair of electrodes is arranged in a sentence unit. In this way, the electrodes are supported using the 18 parts of the drawer 2h system, and the electrostatic quadruple-like lens is drawn out.
By accommodating the ion beam in the lr5 system, the length of the beam line can be maintained at the original length, and it is possible to avoid increasing the size of the ion beam device. FIG. 4 shows the (ff)k arrangement of a magnetic quadruple-like lens that produces the same effect as the electrostatic image electrode lens. The magnetic pole surfaces of four magnetic poles arranged circumferentially at equal intervals are , is formed into a hyperbolic shape with the X and Y directions as the directions of the two axes of rectangular coordinates, and the magnetic flux density in the two axes is B.
y''KX, BX -KY distribution. By arranging a plurality of magnetic pole pair units consisting of four magnetic poles formed in this way on the center 1ijILA perpendicular to the plane of the paper, A lens effect similar to that of the electrostatic 4x+i lens can be provided.

【Effect of the invention】

As described above, according to the present invention, the ion beam focusing means for focusing the ion beam is interposed between the ion extraction section and the 'Etft analysis section, and the ion beam ejected from the ion extraction section is focused. However, since this focused ion beam was made to enter the fft1 analysis section, beam 1! Even if the flow increases or the beam line between the ion extraction section and the ffff1 analysis section is long, the entire beam current can be introduced between the magnetic poles of the analysis magnet in the ffff1 analysis section without increasing the distance between the magnetic poles. Since the magnetic field between the two magnetic fields is kept constant, the entire amount of specific ions in the beam current can be introduced into the next stage acceleration section, making the n-quantity splitting section larger. without doing,
Therefore, it is possible to obtain an ion beam apparatus that can process a large current with high beam utilization efficiency without increasing the size of the ion beam roasting apparatus.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the configuration and operation of an ion beam focusing means according to an embodiment of the present invention, and FIG. 2 is a plane view of the ion beam focusing means as seen in the direction of the arrow at the A-A position in FIG. Figure 3 is a vertical cross-sectional view showing an example of a method of supporting the ion beam focusing means shown in Figure 1, and Figure 4 shows the arrangement of magnetic poles and the shape of the magnetic pole surface when the ion beam is a magnetic four-electrode lens. FIG. 5 is a diagram showing the principle of the configuration of a conventional ion beam device. 1: plasma generation section, 2: ion extraction section, 3: fff
f1 analysis section, 10: sample, 12: electrostatic quadrupole lens (ion beam focusing means), 104: acceleration section, 124
: Support insulator. 1115.・,10. is ′・one′ Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Scope of Claims] 1) A plasma generation section that turns introduced raw material gas or metal vapor into plasma, an ion extraction section that extracts ions with a specific polarity from the plasma in this plasma generation section, and this ion extraction section. a mass spectrometer that extracts only ions with a specific charge/mass ratio from among the ions extracted by the mass spectrometer; an acceleration section that imparts a predetermined kinetic energy to the ions extracted by the mass spectrometer; In an ion beam apparatus that implants ions by irradiating the surface of the sample with the ion beam, the ion beam apparatus includes a lens system that focuses an ion beam made of the specific ions to be ejected onto the surface of the sample, the ion extractor and the mass spectrometer. An ion beam device characterized in that an ion beam focusing means is interposed between the ion beam and the ion extraction section to focus the ion beam emitted from the ion extraction section, and the focused ion beam is made to enter the mass spectrometer. . 2) In the apparatus according to claim 1, the ion beam focusing means interposed between the ion extraction section and the mass spectrometry section includes four columnar electrodes arranged parallel to and around the ion beam. Multiple stages of unit electrode pairs are arranged surrounding the ion beam at equal intervals in the direction and are alternately charged with different polarities. An ion beam device characterized by being an electrostatic quadrupole lens arranged in. 3) In the apparatus according to claim 1, the ion beam focusing means interposed between the ion extraction section and the mass spectrometry section includes four columnar magnetic poles arranged parallel to and around the ion beam. Multiple stages of unit magnetic pole pairs are arranged surrounding the ion beam at equal intervals in the direction, and each magnetic pole face facing the ion beam is configured to have a different polarity alternately, with each magnetic pole having the same polarity as the previous stage at a 90° angle. An ion beam device characterized by a magnetic quadrupole lens arranged in the direction of the ion beam so as to be shifted in the circumferential direction. 4) In the apparatus according to claim 1, the ion beam focusing means interposed between the ion extraction section and the mass spectrometry section is configured to An ion beam device characterized in that the ion beam device is supported by a conductor drawn out from the section via a support member made of an insulating material.