Ion mass analyzer and ion implantation device

Abstract

The application discloses an ion mass analyzer and an ion implantation device. The ion mass analyzer comprises a magnetic yoke, first and second magnetic poles symmetrically arranged above and below the magnetic yoke, a beam line cavity between the first and second magnetic poles for a mixed ion beam to pass through in a certain route, a first coil wound on the first magnetic pole, and a second coil wound on the second magnetic pole. The first and second magnetic poles are both fan-shaped, the incident surfaces of the first and second magnetic poles are both concave, the outgoing surfaces of the first and second magnetic poles are both convex, the curvature of the concave surface is -0.8 to -0.5, and the curvature of the convex surface is 0.45 to 0.6. The angle between the mixed ion beam line and the normal line of the incident surface is 56.5 to 60 degrees when the mixed ion beam is incident, and the angle between the deflected ion beam line and the normal line of the outgoing surface is -10.5 to -13 degrees when the mixed ion beam is outgoing. The resolution of the ion mass analyzer is greater than 200.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor device manufacturing control, and in particular relates to a dual-focusing ion mass analyzer and an ion implantation device. Background Art

[0002] Ion implanters are common equipment in semiconductor component manufacturing. Their primary function is to manipulate dopant ions through various electrical and magnetic devices, ultimately implanting them into substrate materials to achieve material modification. With the advancement of science and technology, the importance of ion implantation in the semiconductor field has become increasingly prominent. The requirements for implanted ion energy, dopant type, doping depth, and implantation angle have become more precise, and the design requirements for ion implantation components have become even greater challenges.

[0003] The selection of dopant type is one of the goals that ion implanters must achieve. A mass analyzer can screen dopant ions, separating ions of different mass-to-charge ratios in the ion beam extracted from the source based on spatial position, temporal order, or stability of their orbits. The mass analyzer is also a key ion optical component with focusing properties. Commonly used mass analyzers include quadrupole, time-of-flight, ion hydrazine, electrostatic electromagnetic sector, electrostatic field orbital hydrazine, and Fourier transform ion cyclotron resonance. Ion implantation equipment more often uses electrostatic electromagnetic sector mass analyzers, where the magnetic field is confined to a sector-shaped area, leaving both the object and image outside the field. Furthermore, the analyzer offers greater flexibility in terms of deflection angle, dispersion, and focusing, leading to its widespread application.

[0004] A key performance metric for mass analyzers is mass resolution (m / Δm). Mass resolution refers to the analyzer's ability to precisely separate a mass peak with mass m from an adjacent peak with a mass difference of Δm. The mass analyzers in current ion implanters typically have a resolution below 100, which is significantly insufficient for certain requirements, especially those requiring high resolution. Research on related design is still lacking, so studying this issue is of great practical significance. Summary of the Invention

[0005] The object of the present invention is to provide an ion mass analyzer and an ion implantation device to solve the problem of low resolution of existing mass analyzers.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: an ion mass analyzer comprising a magnetic yoke, a first magnetic pole and a second magnetic pole disposed in the magnetic yoke and symmetrically distributed vertically, a beamline cavity located between the first magnetic pole and the second magnetic pole and through which a mixed ion beam passes along a certain path, a first coil wound around the first magnetic pole, and a second coil wound around the second magnetic pole; the ion mass analyzer is characterized in that:

[0007] The first magnetic pole and the second magnetic pole are both fan-shaped, the incident surfaces of the first magnetic pole and the second magnetic pole are both concave, the exit surfaces of the first magnetic pole and the second magnetic pole are both convex, and the curvature of the concave surface is -0.8 to -0.5, and the curvature of the convex surface is 0.45 to 0.6; the angle between the mixed ion beam line and the normal of the incident surface during incidence is 56.5° to 60°, and the angle between the deflected ion beam line and the normal of the exit surface during exit is -10.5° to -13°.

[0008] Furthermore, the beamline cavity has a curved shape that matches the shapes of the first magnetic pole and the second magnetic pole.

[0009] Furthermore, graphite is laid on the inner wall of the beam cavity.

[0010] Furthermore, the beam line cavity is made of aluminum material.

[0011] Furthermore, the vacuum degree in the beamline cavity is not greater than 5e -7 Torr.

[0012] Furthermore, the yoke is made of the same material as the first magnetic pole and the second magnetic pole.

[0013] Furthermore, the ion mass analyzer can deflect 60keV Kr+ with a deflection angle of 90°.

[0014] The present invention also provides an ion implantation device, comprising an ion source assembly for generating a mixed ion beam, an ion mass analyzer as described above for applying a magnetic field to the mixed ion beam drawn out from the ion source assembly and deflecting it, a mass analysis slit arranged downstream of the ion mass analyzer and allowing a target ion beam in the deflected ion beam to pass through, and a terminal.

[0015] Furthermore, the ion source assembly includes an ion source reaction arc chamber and an extraction electrode.

[0016] Furthermore, the terminal includes a wafer, and the wafer serves as a substrate material on which the target ion beam is implanted.

[0017] Beneficial effects

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The present invention provides an ion mass analyzer and ion implantation device. Based on a sector-shaped magnetic pole, the incident surface of the magnetic pole is designed to be a concave surface with a curvature of 0.5 to 0.8, and the exit surface of the magnetic pole is designed to be a convex surface with a curvature of 0.45 to 0.6. This arc surface design of the incident and exit surfaces provides an additional sextupole field, which plays a role in reducing aberrations. At the same time, during incident, the angle between the mixed ion beam line and the normal to the incident surface is 56.5° to 60°, and during exit, the angle between the deflected ion beam line and the normal to the exit surface is -10.5° to -13°. The tilted arrangement of the ion beam line during incident and exit increases the quadrupole field effect and improves focusing control in the horizontal and vertical directions. The resolution of the ion mass analyzer of the present invention can reach above 200. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 1 is a schematic structural diagram of an ion mass analyzer according to an embodiment of the present invention;

[0022] Figure 2 is a top view of the first magnetic pole or the second magnetic pole in an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of the magnetic field of an ion mass analyzer in an embodiment of the present invention;

[0024] Figure 4 1 is a diagram showing the deflection effect of ions with mass numbers of 200 / 201 in a mass analyzer according to an embodiment of the present invention;

[0025] Figure 5 200 / 201 ion beam separation diagram at a cross section in an embodiment of the present invention;

[0026] Figure 6 is an ion distribution diagram at a cross section in an embodiment of the present invention;

[0027] Figure 7 is a schematic structural diagram of an ion implantation apparatus according to an embodiment of the present invention;

[0028] Figure 8 Schematic diagram of the mass analysis slit structure in an embodiment of the present invention.

[0029] Among them, 1-ion mass analyzer, 11-first magnetic pole, 12-second magnetic pole, 13-beamline cavity, 14-first coil, 15-second coil, 16-magnetic yoke, 17-center track, 2-ion beam, 3-ion source assembly, 4-mass analysis slit, 41-central symmetry axis of the optical path, 5-terminal. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions of the present invention in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0031] The following specific embodiments are used to describe the technical solution of the present application in detail. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0032] like Figure 1 As shown, an ion mass analyzer provided by an embodiment of the present invention includes a magnetic yoke 16, a first magnetic pole 11 and a second magnetic pole 12 arranged in the magnetic yoke 16 and symmetrically distributed in the upper and lower directions, a beam line cavity 13 located between the first magnetic pole 11 and the second magnetic pole 12 and for the mixed ion beam to pass through along a certain route, a first coil 14 wound on the first magnetic pole 11, and a second coil 15 wound on the second magnetic pole 12; the first magnetic pole 11 and the second magnetic pole 12 are both fan-shaped, the incident surfaces of the first magnetic pole 11 and the second magnetic pole 12 are both concave, and the exit surfaces of the first magnetic pole 11 and the second magnetic pole 12 are both convex , and the curvature 1 / R1 of the concave surface is -0.8 to -0.5 (the negative sign indicates a concave surface), and the curvature 1 / R2 of the convex surface is 0.45 to 0.6 (the positive sign indicates a convex surface); the angle θ1 between the mixed ion beam line and the normal of the incident surface during incidence is 56.5° to 60° (the positive sign indicates that the normal and the deflection center are located on both sides of the ion beam respectively), and the angle θ2 between the deflected ion beam line and the normal of the exit surface during exit is -10.5° to -13° (the negative sign indicates that the normal and the deflection center are located on the same side of the ion beam), the deflection center is the center of the central track 17, and the ion beam is deflected along the central track 17, as shown Figure 2 shown.

[0033] The incident surface and the exit surface are distinguished based on the ion beam incident and exiting the ion mass analyzer 1. The side where the ion beam is incident on the first magnetic pole 11 and the second magnetic pole 12 is the incident surface, and the side where the ion beam exits the first magnetic pole 11 and the second magnetic pole 12 after being deflected by the ion mass analyzer 1 is the exit surface. Figure 2The coordinate system shown takes the ion beam forward direction as the z-axis, the direction perpendicular to the z-axis on the horizontal plane as the x-axis, and the direction perpendicular to the horizontal plane as the y-axis. The xz plane is parallel to the incident surface of the beamline cavity 13, and the origin of the coordinate system is located at the incident surface of the beamline cavity 13. Figure 2 In the figure, the first magnetic pole 11 and the second magnetic pole 12 are fan-shaped, the auxiliary dotted line is the designed ion deflection center orbit 17, R1 is the curvature radius of the incident surface, R2 is the curvature radius of the exit surface, and the coordinate system reflects the actual movement direction of the ion beam in the ion mass analyzer 1. The ion beam is incident at an inclination angle θ1 and moves along the z-axis direction. The x-axis direction is the ion dispersion direction, and the y-axis direction is perpendicular to the dispersion direction. The target ion beam is emitted at an inclination angle θ2 and passes through the mass analysis slit 4, and converges at the mass analysis slit 4 along the x-axis direction.

[0034] The first magnetic pole 11 and the second magnetic pole 12 are both planar magnetic poles. After external excitation is applied to the first coil 14 and the second coil 15, a vertical uniform magnetic field is generated between the first magnetic pole 11 and the second magnetic pole 12 (the direction of the arrow is the direction from the N pole to the S pole, and the magnetic field is perpendicular to the dispersion direction). Figure 3 As shown, the mixed ion beam 2 extracted from the extraction electrode enters the magnetic field from the entrance of the beamline cavity 13. The mixed ion beam 2 is bent and deflected in the beamline cavity 13 by the Lorentz force F (or magnetic field force). The ions with larger mass-to-charge ratio are deflected toward the outer radius, and the ions with smaller mass-to-charge ratio are deflected toward the inner radius. The target ions are deflected along the designed central orbit 17, where the Lorentz force F = qv × B = mv 2 / R, q is the charge state, v is the velocity of the charged ion, B is the magnetic induction intensity, m is the ion mass, and R is the deflection radius of the ion.

[0035] The first magnetic pole 11 and the second magnetic pole 12, which are symmetrical and fan-shaped, provide a dipole field, that is, a uniform magnetic field By in the y-axis direction, and the ion beam is deflected along the center of the orbit; the ion beam enters the magnetic field at an inclination angle θ1 and is deflected from the magnetic field at an inclination angle θ2. The inclination design of the ion beam on the incident and exit surfaces increases the quadrupole field effect and provides focusing control in the horizontal and vertical directions; at the same time, the incident and exit surfaces of the first magnetic pole 11 and the second magnetic pole 12 are both curved surfaces, providing an additional sextupole field. The curved surface design has the effect of weakening aberrations. Parameters such as the shape of the magnetic pole incident and exit surfaces, the object distance, and the image distance jointly determine the resolution of the ion mass analyzer 1. The resolution can be calculated using the following existing formula:

[0036]

[0037] in, is the mass resolution, S1 is the object slit width, S2 is the image slit width, i.e. the slit width, h 13 is the contribution of momentum offset to the particle's displacement in the x direction, Y His the linear magnification in the x direction, E is the ion beam energy, and ΔE is the energy deviation. When calculating the mass resolution, first construct a mathematical model of the ion mass analyzer 1 of the present invention, calculate the total transmission matrix based on the mathematical model, and obtain Y H 、h 13 , and S2 is obtained from the beam envelope calculation results, and finally the theoretical mass resolution is calculated by formula (1).

[0038] When the curvature of the concave surface is -0.76, the curvature of the convex surface is 0.466, θ1 is 60°, and θ2 is -13°, the theoretical mass resolution of the ion mass analyzer 1 of the present invention is 213 (greater than 200), which can completely separate the single-charged ions with mass numbers of 200 and 201. In addition, the focusing effect in the x-direction and y-direction shortens the focal length and can reduce the overall length of the optical path, which means cost savings for the ion implantation device. Figures 4-6 The simulation diagram shown, Figure 4 This is a diagram showing the deflection effect of ions with mass numbers of 200 / 201 in the ion mass analyzer of the present invention. Ion beams with different mass numbers are completely separated at the back end of the ion mass analyzer. Figure 5 The cross-sectional position shown (i.e. the position of the analytical slit) and the distribution of the ion beam at the cross-sectional position are shown in FIG. Figure 6 As shown, the simulation results show that the ion beams with mass numbers of 200 / 201 can be completely separated after being deflected by the ion mass analyzer of the present invention. The ion mass analyzer can separate ions with mass numbers of 200 / 201, and the mass resolution is greater than 200.

[0039] The ion mass analyzer 1 of the present invention can deflect 60keV Kr+ with a deflection angle of 90°. Its geometric design enables the central plane of the magnetic pole to have a high magnetic field, and the magnetic field decays rapidly in the magnetic pole inlet and outlet regions.

[0040] In a specific embodiment of the present invention, graphite is laid on the inner wall of the beam-line cavity 13 . The graphite can prevent the ion beam from directly sputtering onto the inner wall of the beam-line cavity 13 , thereby protecting the beam-line cavity 13 .

[0041] In a specific embodiment of the present invention, the beamline cavity 13 is made of aluminum material, and its shape is a curved shape matching the shapes of the first magnetic pole 11 and the second magnetic pole 12 .

[0042] In a specific embodiment of the present invention, the yoke 16 is made of the same material as the first magnetic pole 11 and the second magnetic pole 12 . The yoke 16 conducts the magnetic circuit and fixes the positions of the magnetic poles and the coil.

[0043] like Figure 7As shown, an ion implantation device provided by an embodiment of the present invention includes an ion source component 3 for generating a mixed ion beam 2, an ion mass analyzer 1 as described above for applying a magnetic field to the mixed ion beam 2 drawn out from the ion source component 3 and deflecting it, a mass analysis slit 4 arranged downstream of the ion mass analyzer 1 and allowing a target ion beam in the deflected ion beam to pass through, and a terminal 5. The ion source assembly 3 includes an ion source reaction arc chamber and an extraction electrode. A mixed ion body containing target ions and other impurities is generated in the ion source reaction arc chamber. The ion source material can be a gaseous source or a solid source. The extraction electrode provides an electric field force to attract the mixed ions from the arc chamber to form a mixed ion beam 2. After being accelerated to the required energy, the mixed ion beam 2 enters the ion mass analyzer 1 for screening after a period of drift. The ion beam 2 moves in the beamline cavity 13 and is bent and deflected by the magnetic field. The ion mass analyzer 1 screens the mixed ion beam 2 according to the different mass-to-charge ratios. The screened ion beam is emitted from the exit of the beamline cavity 13 and converges at the mass analysis slit 4. Other impurity ions are blocked during the movement through the mass analysis slit 4. Finally, the target ions enter the terminal 5 for implantation. The terminal 5 includes a wafer, which serves as a substrate material for the ion beam to be implanted. The terminal 5 also includes wafer handling equipment to provide wafer handling and other tasks.

[0044] like Figure 8 The mass analysis slit 4 shown in the figure is the central symmetry axis 41 of the optical path, which is the ideal trajectory of the target ion beam after it is emitted from the ion mass analyzer 1. The slit width is related to the resolution of the ion mass analyzer 1. The narrower the slit width, the higher the resolution. However, the analysis slit cannot be infinitely reduced, otherwise the beam passing rate will be reduced. Therefore, the width design of the mass analysis slit 4 needs to take into account both the resolution and the beam passing efficiency. The mass analysis slit 4 is located downstream of the ion mass analyzer 1 and is aligned with the exit port of the ion mass analyzer 1 in the optical path, so that the target ions are deflected and emitted according to the deflection angle designed by the ion mass analyzer 1 and can pass through the mass analysis slit 4 smoothly to complete the mass screening.

[0045] The ion implantation device may also include other optical elements that can be used for this implantation device, such as acceleration, deceleration, focusing, and deflection. The entire ion implantation device should also include necessary measurement elements to accurately measure the implanted ion beam to ensure the process quality of the ion beam.

[0046] The above disclosure is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or modifications within the technical scope disclosed in the present invention, and they should all be covered by the scope of protection of the present invention.

Claims

1. An ion mass analyzer comprising a magnetic yoke, a first magnetic pole and a second magnetic pole disposed within the magnetic yoke and symmetrically distributed vertically, a beamline cavity located between the first magnetic pole and the second magnetic pole and through which a mixed ion beam passes along a predetermined path, a first coil wound around the first magnetic pole, and a second coil wound around the second magnetic pole; characterized in that: The first magnetic pole and the second magnetic pole are both fan-shaped and planar magnetic poles. When external excitation is applied to the first coil and the second coil, a uniform magnetic field in a vertical direction is generated between the first magnetic pole and the second magnetic pole. The incident surfaces of the first magnetic pole and the second magnetic pole are both concave surfaces, and the exit surfaces of the first magnetic pole and the second magnetic pole are both convex surfaces. The curvature of the concave surface is -0.8 to -0.5, and the curvature of the convex surface is 0.45 to 0.

6. During incidence, the angle between the mixed ion beam line and the normal of the incident surface is 56.5° to 60°, and during exit, the angle between the deflected ion beam line and the normal of the exit surface is -10.5° to -13°.

2. The ion mass analyzer according to claim 1, wherein: The beamline cavity has a curved shape that matches the shapes of the first magnetic pole and the second magnetic pole.

3. The ion mass analyzer according to claim 1, wherein: Graphite is laid on the inner wall of the beam line cavity.

4. The ion mass analyzer according to claim 1, wherein: The beam line cavity is made of aluminum material.

5. The ion mass analyzer according to claim 1, wherein: The vacuum degree in the beam line cavity is not greater than 5e -7 Torr.

6. The ion mass analyzer according to claim 1, wherein: The yoke is made of the same material as the first magnetic pole and the second magnetic pole.

7. The ion mass analyzer according to any one of claims 1 to 6, characterized in that: The mass analyzer can deflect 60keV Kr+ with a deflection angle of 90°.

8. An ion implantation apparatus, characterized in that: The invention comprises an ion source assembly for generating a mixed ion beam, an ion mass analyzer as described in any one of claims 1 to 7 for applying a magnetic field to the mixed ion beam drawn out from the ion source assembly and deflecting the mixed ion beam, a mass analysis slit arranged downstream of the ion mass analyzer and allowing a target ion beam in the deflected ion beam to pass through, and a terminal.

9. The ion implantation apparatus according to claim 8, wherein: The ion source assembly includes an ion source reaction arc chamber and an extraction electrode.

10. The ion implantation apparatus according to claim 8 or 9, wherein: The terminal includes a wafer as a substrate material onto which the target ion beam is implanted.

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