JPH01252773A - Ion implantation equipment - Google Patents

Abstract

PURPOSE:To easily carry out high-precision ion implantation by means of a simplified electric power source by constituting the deflection scanning systems for an ion beam of a magnetic deflecting system for removing neutral particles, a multipole deflecting system for scanning, and another magnetic deflecting system which are capable of independent voltage control, respectively. CONSTITUTION:Ions produced in an ion source 1 are subjected to mass spectrometry by means of an analyzer magnet 2 and accelerated by means of an accelerating tube 3. The resulting ion beam is passed through a focusing lens 4 and then implanted in a specimen 8 via deflection scanning systems. In the above ion implantation equipment, the above deflection scanning systems are constituted of a magnetic deflecting system 5 for removing neutral particles, a multipole deflecting system 7 for scanning, and another magnetic deflecting system 6 provided between the above deflecting systems 5, 7 and used for deflecting the ion beam parallel to the optical axis after concentration, and these deflecting systems 5-7 are made capable of independent voltage control, respectively. By this method, the electric power source for the deflecting systems 5-7 can be simplified and also applied voltage can be maintained at relatively low values. Further, it is preferable that the above muitipole deflecting system 7 for scanning is constituted of a first multipole deflectng system and a second multipole deflection system for deflecting the direction of the ion beam deflected by means of the above first multiple deflecting system to the prescribed direction with respect to the specimen 8 surface.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention introduces ions generated in an ion source into a mass spectrometry system, extracts ions with the required kinetic energy and mass, and collects them in an acceleration tube. The present invention relates to an ion implantation device that implants ions into a sample via a deflection scanning system after acceleration.

[Conventional technology] As is well known, ion implantation technology performs impurity doping and material synthesis by accelerating ions and irradiating them onto the sample surface, and it is possible to perform doping without being affected by the condition of the sample surface. This is an extremely precise and clean impurity doping technology, and by taking advantage of this feature, LSI and ultra-LSI
It is used for manufacturing elements and synthesizing alloys or amorphous materials.

Incidentally, as shown in FIG. 7 of the accompanying drawings, an ion implantation apparatus generally includes an ion source A and an analysis magnet B, and extracts ions having the required kinetic energy and mass from the ions generated by the ion source A. an acceleration system consisting of a mass spectrometry system that extracts the ions, and an acceleration tube C that accelerates the extracted ions;
A focusing lens system, a deflection scanning system including a Y-direction scanning electrode E and an X-direction scanning type iF, and a sample G to be ion-implanted.
It consists of a sample chamber containing a In an ion implanter, it is important to stabilize the ion source and scanning system and to suppress the generation of neutral beams in order to obtain high doping uniformity. The neutral beam collides with residual gas molecules before the ion beam reaches the sample from the ion source.
It is generated by charge exchange, and the probability of this happening increases as the degree of vacuum deteriorates and the distance traveled becomes longer. Therefore, in order to suppress the generation of neutral beams in ion implanters, the degree of vacuum is increased and the beam line is bent (about 7 degrees) in the deflection scanning system to prevent the neutral beams from entering the sample, as shown in Figure 7. Measures such as these are being taken. That is, electrically, the voltage is controlled by superimposing a DC bias for directing the ion beam 7 degrees on the scanning triangular wave of the X-direction scanning electrode F.

[Problems to be Solved by the Invention] In the conventional ion implantation apparatus of this type, the effective area for suppressing electric field disturbance at the end of the deflection scanning system is narrow, so the width must be increased, and the electrode becomes large. , as the capacitance increases, the deflection distortion increases considerably. Furthermore, since the triangular wave voltage for scanning and the deflection voltage for neutral particle removal are superimposed and applied to at least one scanning iS pole of the deflection scanning system, the voltage applied to f4[# becomes high.
High voltage generation is required. Therefore, when scanning at high speed, the triangular wave voltage becomes dull and the voltage becomes 10kV.
If it exceeds this, it becomes difficult to take measures against corona discharge and leakage.
It is difficult to design and manufacture a power supply, and the cost is also high.

Furthermore, the life of the power supply is short, and there are also problems in terms of power loss.

Furthermore, in conventional ion implanters, constant-angle deflection is performed behind the Q lens to remove neutron particles, so the ion beam line from the ion source and the optical axis of the scanning system are not parallel, making it difficult to assemble the device. The layout is dragon-like.

On the other hand, in the process of forming shallow junctions in ion implantation technology, low energy and high ion current strength are required. There are the following problems when incorporating this low-energy ion source into a conventional ion implanter.

Generally speaking, the characteristics of low-energy ions are that ions repel each other due to their own electric charge, and the lower the energy, the stronger the repulsive force is, so the ions spread during beam transport and are lost before reaching the wafer. It is difficult to obtain current strength, and low-energy ions have a high probability of capturing electrons and becoming neutral while being transported through the vacuum, which means a reduction in beam current. The degree of this decrease increases as the degree of vacuum worsens, and as the distance of transport increases, the lower the energy value, the earlier acceleration voltage applied to the ion source is sufficient, and the later acceleration is zero. good.

In recent years, as wafers have become finer in ion implantation technology and pattern widths have become narrower, shadowing has become a problem. For this reason, it is necessary to perform ion implantation from a fixed direction over the entire surface of the wafer, but with conventional ion implanters, the deflection angle θ increases as the radius from the center of the evaporator increases, and the ion implantation depth is vertical. Since it is determined by the component, the implantation becomes shallower toward the outer periphery of the wafer, and the implantation distribution within the wafer surface becomes less uniform.

If we were to try to suppress the deflection angle θ within a certain level when implanting large diameter wafers, the beam transport system would need to be long, which would increase the size of the entire device and increase the installation area, which would affect production costs. .

With the miniaturization of wafers, the aspect ratio of trenches is increasing, and when implanting ions into the bottom of such a trench, if the ion beam to be implanted has a deflection angle θ, it will not be able to cover the entire bottom. This can be alleviated to some extent by implanting while rotating the wafer, but
Not enough.

In addition, when implanting into the sides of a trench, the wafer is tilted according to the aspect ratio of the trench to prevent shadowing, but it is difficult to obtain a similar implantation distribution.
Furthermore, if ions are implanted obliquely to the side surfaces of the trench, there is a risk that some ions may not be implanted and may bounce back, or that some side surfaces may not be implanted.

In other words, the diameter of the wafer has increased to 6 inches and 8 inches,
As the line width becomes smaller from 4M bits to 16M bits, it has become desirable to perform ion implantation using a parallel ion beam.

From this perspective, the problems to be solved by the present invention are to solve the problems associated with the power supply of the deflection scanning system, to facilitate assembly of the device and improve alignment accuracy, and to do so without changing the operation mode or reducing the beam current. The object of this invention is to realize low-energy ion implantation and to make uniform ion implantation onto the sample surface possible.

[Means for Solving the Problems] In order to solve the above-mentioned problems of the present invention, the first object of the present invention is to separate the deflection function and the scanning function of the deflection scanning system,
An object of the present invention is to provide an ion implantation device in which an ion beam line from an ion source and an optical axis of a scanning system are made parallel to each other in a neutral particle removal deflection section. A second object of the present invention is to separate the deflection function and scanning function of the deflection scanning system, and to make the ion beam line from the ion source parallel to the optical axis of the scanning system in the neutral particle removal deflection section. It is an object of the present invention to provide an ion implantation device in which a low energy ion source is incorporated in a deflection section for removing neutral particles.

A third object of the present invention, in addition to the above objects, is to provide an ion implantation apparatus that implants ions into a sample in parallel scanning, that is, with zero deflection angle.

In order to achieve the above first object, the ion implantation apparatus according to the first aspect of the present invention includes a magnetic deflector for neutral particle removal and a multipole deflector for scanning, in which the deflection scanning system is independently voltage controlled. and deflecting the ion beam from the neutral particle removal magnetic deflector parallel to the optical axis of the ion beam before entering the neutral particle removal magnetic deflector. It is characterized by the provision of another magnetic deflector.

In addition, in order to achieve the above second object, the ion implantation apparatus according to the second aspect of the present invention includes a magnetic deflector for removing neutral particles whose deflection scanning system is independently voltage controlled, and a multipole deflector for scanning. and a magnetic deflector for neutral particle removal which deflects the ion beam from the magnetic deflector for neutral particle removal parallel to the optical axis of the ion beam before entering the magnetic deflector for neutral particle removal. The present invention is characterized in that a separate magnetic deflector is provided to remove neutral particles, and a low-energy ion source using a solid sample is connected to the neutral particle removal magnetic deflector or another magnetic deflector.

Furthermore, in order to achieve the third object, in the ion implantation apparatus according to the present invention, the scanning multipole deflector in each of the above inventions includes a first multipole deflector and a similar type to the first multipole deflector. It has a structure of
It consists of a multipole profit making device.

In each of the above inventions, the scanning multiple@1 deflector may preferably consist of octupole scanning electrodes.

[Function] In the ion implantation apparatus according to the first aspect of the present invention configured as described above, an OC voltage is applied to the magnetic deflector for removing neutral particles, and a scanning voltage is applied to the scanning multipole deflector. Both voltages can be controlled independently and can be kept relatively low.

The magnetic deflector combined with the neutral removal magnetic deflector deflects the ion beam at the same angle and in the opposite direction to the deflection by the neutral removal magnetic deflector, so that before entering the neutral removal magnetic deflector The optical axis of the ion beam and the optical axis passing through the scanning system are parallel to each other.

Further, in the ion implantation apparatus according to the second invention, in addition to the above-mentioned functions, the low-energy ion source connected to the magnetic deflector for neutral particle removal or another deflector operates the beam line for low-energy ions. low energy ions with the required ion current intensity can be obtained without changing the normal operation mode.

On the other hand, the ion beam can be made parallel to the optical axis by two sets of scanning multipole single-direction devices, and the uniformity of ions implanted into the sample can be improved.

[Embodiments] Examples of the present invention will be described below with reference to the attached drawings.

FIG. 1 shows an embodiment of an ion implantation apparatus according to the present invention, in which 1 is an ion source, 2 is an analysis magnet for extracting ions with required kinetic energy and mass from the ions from the ion source 1, and 3 is an ion implanter. An acceleration tube accelerates the ions extracted by the analysis magnet 2, and 4 is a Q lens, that is, a focusing lens, which focuses the ions that have been accelerated through the acceleration tube 3.
Reference numeral 5 denotes a constant angle magnetic deflector consisting of an electromagnet for trapping neutrons in the ion beam that has passed through the analysis magnet 2, acceleration tube 3 and focusing lens 4 from the ion source 1; Another constant angle magnetic deflector 6 is provided adjacently.

The fixed-angle magnetic deflector 5 for neutron removal and another fixed-angle magnetic deflector 6 have opposite polarities and the same deflection angle, so that the ion beam entering the fixed-angle magnetic deflector 5 for neutron removal The optical axis of the ion beam and the optical axis of the ion beam deflected by another fixed-angle magnetic deflector 6 are parallel to each other as shown.

7 is for neutron removal and another constant angle magnetic deflector 5.
At 6, the direction of the ion beam deflected at a certain angle is taken as the central axis, and the ion beam is scanned simultaneously in the X direction and the Y direction. The components are arranged in the order shown.

FIG. 2 shows another embodiment of the present invention, which is equipped with two stages of scanning deflectors and a low-energy ion source using a solid sample in another fixed-angle magnetic deflector 6. Although this embodiment differs from the embodiment shown in FIG. 1 in that it is connected, the other configurations are substantially the same as the embodiment shown in FIG. 1, and corresponding parts are designated by the same reference numerals.

That is, in FIG. 2, the scanning deflector has two sets of octupole electrodes, that is, a first beam whose central axis is the direction of the ion beam deflected at a constant angle by another constant angle magnetic deflector 6.
The pole collector 9 and the first octupole [f! The second octupole electrode 10 is larger in size than the polar electrode 9. 1st
Nohe Shikoku Den [! 9 and the second octupole electrode 10 are electrically connected as shown in FIG. 3, ie to the first f!
Each electrode in the polar electrode 9 is connected to an electrode in the second octupole electrode 10 located symmetrically with respect to the central axis, and voltages as shown are applied to each electrode by four sawtooth wave power sources (not shown). .

Further, a low-energy ion source 11 using a solid sample is connected to another constant-angle magnetic deflector 6 so as to be aligned with the optical axis on the output side of the other constant-angle magnetic deflector 6 .

Next, the operating principle of the apparatus shown in FIG. 2 will be explained with reference to FIG. 4.

As shown in Fig. 4, the diameter of the first claw-shaped electrode 9 is dl.
, its length is Ql, and the diameter of the second octupole electrode 10 is d2.
, its length is Q2, the distance between the two claw electrodes is El, the electric field in the first octupole electrode 9 is El, the electric field in the second octupole electrode 10 is E2, and the distance between the two claw electrodes is E1. The exit angle (deflection angle) with respect to the central axis of the ion beam on the exit side of the pole is 01
, second claw type'! f! The exit angle ((?i direction angle) with respect to the central axis of the ion beam on the exit side of the electrode 10 is 02
, and if the energy of the ions before entering the first octupole electrode 9 is UO, then tanθ1 = E1 Ql /2UO tanθ2 = EI Qi /2UO −E2Q2/2UO (1), where EIQ1/2tJO = E2Q2 If /2UO(2) is established, tan θ2=0, and the parallel sweep condition is obtained.

By the way, the first and second fil electrodes 9 and 10 have similar shapes, and as shown in FIG. Toni V, t
′! 1/J2 (U+V) for f19b and 9@10b,
When the same voltage, such as U, is applied to the electric fields E1 and E2, the electric fields E1 and E2 are parallel to each other and have opposite directions.
Each is given by the following formula.

E1=λV/d1, E2=λV/d2 (3) Substituting this into equation (2), it is expressed as λV/UO・Ql/d1=λV/UO・Q2/d2, where the first and second Since the octupole electrodes 9 and 10 of No. 2 are similar, Ql /d1= Q2 /d2 (4)
By multiplying both sides of this equation by λvt-m, we get λV-Q1/
Old=λV−Q2/d2 is obtained, so El Ql =E2 Q2 and the parallel sweep condition of equation (2) can be satisfied.

Also, considering the voltage applied to each electrode of the first and second octupole electrodes, for convenience, we will consider a cylindrical deflector as shown in Fig. 5, and generate a −-like electric field V/ro in the X direction. Let's consider what kind of potential should be applied to the circumference of that cross section in order to make this happen.

Considering a radius OP forming an angle θ with respect to the X direction, and assuming that the potential at point P is φ, φ=V/ro − rosinθ=Vsinθ. That is, if a potential distribution such as V sin θ is given on the circumference, a −-like electric field of V/ro will be generated in the X direction within the cylinder. Similarly, if a potential distribution such as U cos θ is given, a −-like electric field of U/ro will be generated in the X direction inside the cylinder. Therefore, Vsinθ on the circumference
Given a potential distribution like +Ucosθ, U/r
In the case of the electrode of the illustrated embodiment, where an electric field E such as - is obtained by superimposing an electric field in the X direction having a magnitude of O and an electric field in the X direction having a magnitude of V/ro, Vs1nθ+Uc
osθ becomes as shown in FIG.

Figure 6 shows an example of the voltage waveform, 1/J2 (U + V)
etc. can be formed by combining the U and V waveforms using an adder.

Incidentally, although bipolar scanning electrodes are used in the illustrated embodiment, it is of course possible to use multipole scanning N & with less than or more than the electrodes.

In addition, in the embodiment of FIG. 1, the scanning deflector can be constructed in two stages as in the embodiment of FIG. A low-energy ion source can also be incorporated into the system.

Similarly, the scanning deflector in the embodiment of FIG. 2 may be configured in one stage as in the embodiment of FIG. It can also be incorporated into a constant angle magnetic deflector for removal.

Further, in each embodiment, another fixed-angle magnetic deflector for removing neutrons is arranged after the focusing lens, but it can also be arranged before the focusing lens if necessary.

[Effects of the Invention] As explained above, in the ion implantation apparatus according to the first aspect of the present invention, the deflection scanning system is composed of a magnetic deflector for neutral particle removal and a scanning multiplexer that are voltage controlled independently of each other. By configuring the deflector with a polar deflector, the power supply for the deflector becomes simple, and since the applied voltage is not superimposed, it can be kept relatively low.

Additionally, by using two magnetic deflectors to make the optical axis of the ion beam from the ion source parallel to the optical axis after removing neutral particles, it is easier to assemble the device and align the optical axis. In addition, alignment accuracy can be improved.

In addition to the above-mentioned effects, the ion implantation apparatus according to the second aspect of the present invention can establish a dedicated low-energy ion beam line by connecting a low-energy ion source to a magnetic deflector for removing neutral particles. , there is no need to change the normal operation mode to accelerate low-energy ions, and as a result, the operation becomes easier and the throughput of the apparatus can be improved without reducing the beam current.

Furthermore, by performing parallel scanning using two sets of multiple I#In devices for scanning, the effective range of ion implantation can be widened compared to when parallel plate electrodes are used, and moreover, the effective range of ion implantation can be widened compared to the case where parallel plate electrodes are used. Ion uniformity can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, FIG. 2 is a schematic perspective view showing another embodiment of the present invention, and FIG. 3 is an electrical connection between each electrode of the scanning deflector in FIG. 4 is an explanatory diagram of the principle of parallel scanning, FIG. 5 is an explanatory diagram of the method of applying voltage to each electrode, and 6
The figure is a waveform diagram illustrating the voltage waveform applied to each electrode,
FIG. 7 is a schematic diagram of a conventional ion implanter. Figure Middle 1: Ion source 2: Analysis magnet 3: Accelerator tube 4: Focusing lens 5: Magnetic deflector for neutral particle removal 6: Another magnetic deflector 7: Multipole deflector for scanning 8: Sample to be ion-implanted 9: First multiplex i# for parallel scanning! Deflector 10: Second multipole deflector 11 for parallel scanning: Ion source for low energy Figure 3 Figure 4

Claims (1)

[Claims] 1. Put the ions generated in the ion source into a mass spectrometry system, extract the ions with the required kinetic energy and mass,
In an ion implantation device that accelerates the particles in an accelerating tube and then injects them into a sample via a deflection scanning system, the deflection scanning system includes a magnetic deflector for removing neutral particles whose voltage is controlled independently, and a scanning the optical axis of the ion beam before entering the magnetic deflector for neutral particle removal, and a multipole deflector for directing the ion beam from the magnetic deflector for neutral particle removal to the magnetic deflector for neutral particle removal. An ion implantation apparatus characterized in that an ion implanter is provided with another magnetic deflector that deflects parallel to the ion implanter. 2. Put the ions generated in the ion source into the mass spectrometry system, extract the ions with the required kinetic energy and mass,
In an ion implantation device that accelerates the particles in an accelerating tube and then injects them into a sample via a deflection scanning system, the deflection scanning system includes a magnetic deflector for removing neutral particles whose voltage is controlled independently, and a scanning the optical axis of the ion beam before entering the magnetic deflector for neutral particle removal, and a multipole deflector for directing the ion beam from the magnetic deflector for neutral particle removal to the magnetic deflector for neutral particle removal. Another magnetic deflector is provided for deflecting parallel to the neutral particle, and a low-energy ion source using a solid sample is connected to the neutral particle removal magnetic deflector or the other magnetic deflector. Ion implanter. 3. The scanning multipole deflector in the deflection scanning system has a first multipole deflector and a structure similar to the first multipole deflector, and the ion beam deflected by the first multipole deflector is 3. The ion implantation apparatus according to claim 1, further comprising a second multipole deflector that makes the direction constant with respect to the sample surface. 4. The ion implantation apparatus according to claim 1 or 2, wherein the scanning multipole deflector in the deflection scanning system is an octupole scanning electrode.