JP6428726B2 - Ion implantation system - Google Patents

Description

  The present invention relates to an ion implantation system, and more particularly to an ion implantation system having an electrostatic deflector.

  This application claims priority as a continuation-in-part application based on patent application No. 13 / 833,668, filed March 15, 2013, entitled IonBeamline. This application refers to the same application and is hereby incorporated by reference in its entirety.

  Ion implantation techniques have been employed for over 30 years to implant ions into semiconductors for the purpose of fabricating integrated circuits. Traditionally, three types of ion implanters have been employed for such ion implantation. That is, a medium current, large current and high energy injector. Ion sources incorporated in high current ion implanters typically include a slot shaped extraction aperture having a high aspect ratio to improve space charge effects. A one-dimensional ion beam extracted from such an ion source can also be focused into an elliptical profile to create a substantially round beam profile at the position of the wafer where the beam is incident.

  Some recent commercial high current ion implanters irradiate a wafer with a so-called ribbon ion beam (which nominally exhibits a one-dimensional profile) and implant ions there. The use of such a ribbon ion beam provides several advantages for wafer processing. For example, a ribbon ion beam can have a long dimension that exceeds the diameter of the wafer, and therefore scans the wafer in only one dimension orthogonal to the direction of ion beam travel, in order to implant ions across the wafer. During this time, the ion beam can be kept stationary. Furthermore, the ribbon ion beam can also expect a larger current at the wafer location.

  Examples of an ion source capable of generating a ribbon ion beam are described in Patent Document 1 and Patent Document 2.

US Pat. No. 6,664,547 US Pat. No. 7,791,041

  The use of a ribbon ion beam for ion implantation, however, causes several problems. As an example, a high uniformity of the longitudinal profile of the ion beam is necessary to obtain a satisfactory implantation uniformity of the implanted ions. Achieving satisfactory longitudinal uniformity of ribbon ion beams used to process such wafers as wafer dimensions increase (eg, as next generation 450 mm wafers replace the currently dominant 300 mm wafers) Becomes more difficult.

  In some conventional ion implantation systems, correction optics are incorporated into the ion beam line to partially change the charge density of the ion beam during beam transport. This method, however, provides sufficient ion beam uniformity if the ion beam profile exhibits strong non-uniformities when extracted from the ion source, or due to space charge effects or aberrations caused by beam transport optics. It can't usually be created.

  Accordingly, there is a need for improved systems and methods for ion implantation, including enhanced systems and methods for generating ribbon ion beams with desired energy and high profile uniformity.

  In one aspect, a system for changing the energy of a ribbon ion beam is disclosed, the system receiving a ribbon ion beam and current density along its longitudinal dimension (in other words, the longitudinal dimension, and so on). A correction device configured to adjust a profile; at least one deceleration / acceleration element defining a deceleration / acceleration region for decelerating or accelerating the ion beam as it passes; A focusing lens for reducing divergence along the transverse dimension and an electrostatic deflector arranged downstream of the deceleration / acceleration region to cause deflection of the ion beam.

  In some embodiments, the correction device is a plurality of spaced apart electrode pairs stacked along the longitudinal dimension of the ion beam, and each pair of electrodes passes through the ion beam. A plurality of electrode pairs that are spaced apart to form a gap for the electrodes, and the electrode pairs are configured to be individually biasable by application of an electrostatic voltage thereto, The ion beam is locally deflected along the vertical dimension. A variety of different electrode types may be employed. In some embodiments, the electrode pair may include an electrode plate disposed substantially parallel or perpendicular to a plane formed by a traveling direction of the ion beam and a longitudinal dimension of the ion beam. The energy changing system may further include at least one voltage source for applying the electrostatic voltage to the electrode pair of the correction device.

  A controller that communicates with the at least one voltage source may control the application of the electrostatic voltage to the electrode pair. As an example, the controller directs the voltage source to apply the electrostatic voltage to the electrode pair to locally deflect at least a portion of the ion beam, and You may be comprised so that the uniformity of the current density profile along a dimension may be improved.

  The controller may be configured to apply the electrostatic for application to the electrode pair of the correction device based on, for example, a current density profile of the ion beam measured after passing through the analysis magnet or near the surface of the substrate to which the beam is irradiated. It may be configured to determine the voltage.

  In some embodiments, the controller is configured to apply a time-varying voltage to the electrode pair of the correction device. For example, the controller may be configured to change the voltage applied to the electrode pair of the correction device with time to generate an oscillating motion of the ion beam along the vertical dimension. Such an oscillating motion of the ion beam can exhibit an amplitude of, for example, about 20 mm or less, more specifically in the range of about 10 mm to about 20 mm. As an example, the frequency of the vibration may be in the range of about 1 Hz to about 1 kHz.

  The focusing lens may include at least one focusing element, e.g., a pair of opposing electrodes spaced to form a gap for receiving the ion beam. Further, the deceleration / acceleration element may include a pair of electrodes spaced apart to form a lateral gap for receiving the ion beam. The focusing element and the deceleration / acceleration element may be positioned with respect to each other to form a gap therebetween and are maintained at different voltages from each other so that passage of the ions through the gap It may be designed to cause deceleration or acceleration.

  In some embodiments, at least one of the focusing electrodes may include a curved upstream end surface configured to reduce divergence along the longitudinal dimension of the ion beam. For example, the upstream end surface of the focusing electrode may be a concave surface having a radius of curvature in the range of about 1 m to about 10 m.

  In some embodiments, the at least one deceleration / acceleration element is disposed downstream of the correction device, and the at least one focusing element is disposed downstream of the deceleration / acceleration element. Yes.

  The focusing element may be arranged to form a gap therewith with respect to the electrostatic deflector, and the focusing element and the electrostatic deflector provide divergence along a lateral dimension of the ion beam. Different voltages are kept at different voltages so that an electric field suitable for reduction is generated in the gap.

  In some embodiments, the electrostatic deflector includes an inner electrode that is held at a different voltage and an outer electrode that faces the inner electrode to cause deflection of the ion beam. The electrostatic deflector may further comprise an intermediate electrode disposed downstream of the inner electrode and facing the outer electrode, and the inner electrode and the intermediate electrode are independent of each other It is configured to be suitable for voltage application. In some cases, the outer electrode and the intermediate electrode may be kept at the same voltage.

  In some embodiments, the outer electrode of the electrostatic deflector includes an upstream portion and a downstream portion disposed at a predetermined angle relative to each other, the downstream portion being in the ion beam. At least a portion of the neutral species can be captured. The upstream portion and the downstream portion may integrally form the outer electrode, or they may be separate portions that are electrically connected.

  In some embodiments, the system for changing energy may further comprise another correction device (also referred to herein as a second correction device) disposed downstream of the electrostatic deflector. Preferably, the other correction device is configured to adjust a current density profile along the longitudinal dimension of the ion beam. In some embodiments, the downstream correction device is a plurality of spaced apart electrode pairs stacked along the longitudinal dimension of the ion beam, and each pair of electrodes is coupled to the ion beam. It may include a plurality of electrode pairs spaced apart to form a gap for passage, and the electrode pairs are configured to be individually biasable by applying an electrostatic voltage thereto. Thus, the ion beam is locally deflected along the vertical dimension.

  In some embodiments, the electrode pairs of the correction device are arranged in a staggered manner along the longitudinal dimension of the ion beam. For example, the electrode pair of the downstream correction device is shifted in the vertical direction (along the vertical dimension of the beam) with respect to each electrode pair of the upstream correction device, for example, the vertical height of the electrode of the correction device. They may be shifted by a half (half pixel size).

  In some embodiments, the energy modification system is disposed downstream of the other corrector and includes another focusing lens for reducing divergence along the lateral dimension of the ion beam. In this case, it may also be referred to as a second focusing lens). Further, in some cases, an electrically grounded element may be placed downstream of the other focusing lens. The electrically grounded element may include, for example, a pair of electrically grounded electrodes that are spaced apart from each other to allow the ion beam to pass there between. The second focusing lens may include at least one focusing element arranged to form a gap therewith relative to the ground element, and a voltage between the focusing element and the ground element The difference generates an electric field in the gap to reduce divergence along the lateral dimension of the ion beam.

  In another aspect, a system for decelerating a ribbon ion beam is disclosed, the system defining an area for receiving the ribbon ion beam and at least one decelerating for decelerating the ions. Providing an element, at least a pair of deflection electrodes disposed apart from each other to receive and cause deflection of the decelerated ion beam, and a path for passage of the decelerated ion beam And a correction device configured to adjust the current density profile of the ion beam in a non-dispersion plane.

  In some embodiments, the correction device is a plurality of spaced apart electrode pairs stacked along the longitudinal dimension of the ion beam, and each pair of electrodes passes through the ion beam. A plurality of electrode pairs that are spaced apart to form a gap for the electrodes, and the electrode pairs are configured to be individually biasable by application of an electrostatic voltage thereto, The ion beam is locally deflected along the vertical dimension. In some embodiments, the plurality of spaced apart electrode pairs includes an inner electrode, an outer electrode facing the inner electrode, and an intermediate electrode disposed downstream of the inner electrode and facing the outer electrode. The outer electrode, the inner electrode, and the intermediate electrode may be maintained at independent voltages. As an example, the inner and outer electrodes may be kept at different voltages so as to cause deflection of the ion beam, while the outer and intermediate electrodes may be kept at the same voltage. The outer electrode may include an upstream portion and a downstream portion, and the downstream portion is disposed at an angle relative to the upstream portion so as to capture neutral species in the ion beam. Has been. In some embodiments, the upstream portion and the downstream portion of the outer electrode integrally form the outer electrode.

  The system for deceleration may further include at least one voltage source for applying the electrostatic voltage to the electrode pair of the correction device. A controller that communicates information with the at least one voltage source may be provided to adjust the voltage applied to the electrode pair of the correction device. As an example, the controller may determine a voltage to be applied to the electrode pair of the correction device based on, for example, a measured current density profile of the received ion beam.

  The deceleration system may further include a focusing lens configured to reduce divergence along the lateral dimension of the ion beam. The focusing lens may include at least one focusing element, eg, a pair of electrodes spaced to allow passage of an ion beam. In some embodiments, an electrically grounded element, such as a pair of spaced electrodes, is disposed downstream of the focusing element. The electrically grounded elements may be arranged to form a gap therebetween with respect to the focusing element. The grounding element and the focusing element may be held at different voltages to generate an electric field in the gap that is suitable to reduce divergence along the lateral dimension of the ion beam.

  In another aspect, an ion implantation system is disclosed that includes an ion source configured to generate a ribbon ion beam, and a mass-selected ribbon ion beam that receives the ribbon ion beam. An analysis magnet for generating and an output ribbon ion having a substantially uniform current density profile along the longitudinal dimension by receiving the mass-selected ribbon ion beam and adjusting a current density profile along the longitudinal dimension thereof And a correction system configured to generate the beam.

  In some embodiments, the correction system further decelerates or accelerates ions of the received mass-selected ion beam to be decelerated / accelerated having a substantially uniform current density profile along the longitudinal dimension. Alternatively, an output ribbon ion beam may be generated. In some embodiments, the output ribbon ion beam exhibits a current density profile along the longitudinal dimension having a root mean square (RMS, also called effective) deviation (ie, non-uniformity) of about 5% or less. For example, the output ribbon ion beam is along the longitudinal dimension having an RMS deviation (ie, non-uniformity) of about 4% or less, or about 3% or less, or about 2% or less, or about 1% or less. A current density profile can be shown.

  In some embodiments, the correction system in the ion implantation system may further include a focusing lens to reduce divergence along the lateral dimension of the ribbon ion beam. Further, in some embodiments, the correction system is configured to remove at least a portion of neutral species such as neutral atoms and / or molecules present in the mass-selected ion beam. May be. For example, the correction system changes the traveling direction of the ions in the ion beam, while continuing to advance the neutral species along the traveling direction, such as a portion of the outer electrode of the electrostatic deflector. An electrostatic deflector may be included so as to be captured by a proper beam stop.

  The ion implantation system may further include an end station for holding a substrate, such as a wafer, and the output ribbon ion beam travels toward the end station to be incident on the substrate. . In some embodiments, the correction system adjusts the direction of travel of the ion beam so that the output ribbon ion beam forms a desired angle with respect to the substrate surface, eg, a 90 degree angle. You may be comprised so that it may inject.

  In some embodiments, the correction system of the ion implantation system produces an oscillating motion of the ion beam to improve implantation uniformity of ions implanted into the substrate by the output ribbon ion beam. Can do.

  In some embodiments, the correction system of the ion implantation system may include at least one correction device for adjusting a current density profile along a longitudinal dimension of the ion beam. Such a correction device is, for example, a plurality of spaced electrode pairs stacked along the longitudinal dimension of the ion beam, and each pair of electrodes has a gap for passage of the ion beam. A plurality of electrode pairs spaced apart so as to form an ion beam, the electrode pairs being individually biasable by application of an electrostatic voltage thereto, the ion beam Is locally deflected on the non-dispersive surface. The ion implantation system also includes at least one voltage source for applying a voltage to the electrode pair of the correction device, and communicates with the at least one voltage source to regulate a voltage applied to the electrode pair. And a controller.

  In some aspects, a method for altering the energy of a ribbon ion beam is disclosed, the method passing the ribbon ion beam through a region where an electric field exists to decelerate or accelerate the ions. Adjusting a current density profile along the longitudinal dimension of the ribbon ion beam; and reducing divergence along the lateral dimension of the ribbon ion beam. Reducing the ion beam divergence may include passing the ion beam through a focusing lens.

  In some embodiments, the ribbon ion beam may have an initial energy in the range of about 10 to about 100 keV. In some embodiments, the step of decelerating or accelerating ions of the ion beam changes the energy of the ion beam within a range of about 1 to about 30 times.

  The step of adjusting a current density profile along the longitudinal dimension of the ion beam is configured to locally deflect the ion beam along the longitudinal dimension, so that a substantially uniform current along the longitudinal dimension. A step of using a correction device adapted to generate a density profile may be included.

  In some aspects, a method of implanting ions into a substrate is disclosed, the method including extracting a ribbon ion beam from an ion source and generating the mass selected ribbon ion beam. And passing the mass density selected ribbon ion beam current density profile to at least its longitudinal dimension to generate an output ribbon ion beam having a substantially uniform current density profile along the longitudinal dimension. And adjusting the output ribbon ion beam toward the substrate to inject ions into the substrate.

  In some embodiments, a correction device may be configured to perform the step of adjusting a current density profile of the mass selected ribbon ion beam. As an example, the correction device may adjust the current density profile of the mass-selected ribbon ion beam to obtain an ion beam that exhibits a substantially uniform current density profile.

  In some embodiments, the ion implantation method decelerates or accelerates the mass selected ribbon ion beam such that the output ribbon ion beam has a different energy than the mass selected ribbon ion beam. May further be included.

In some embodiments, the implanted dose of ions may be in the range of about 10 ¹² cm ⁻² to about 10 ¹⁶ cm ⁻² . The ion current is, for example, in the range of tens of microamperes (eg, 20 microamperes) to tens of milliamperes (eg, 60 milliamperes), more specifically in the range of about 50 microamperes to about 50 milliamperes, or about 2 It may be in the range of about 50 milliamperes from milliamperes.

In many ion implantation systems, an electrostatic deflector, as described above, consisting of two spaced apart electrodes is placed downstream of the deceleration / acceleration system and operates to decelerate received ions at a moderate rate of deceleration. Even when the electrostatic deflector is used, the electrostatic deflector can effectively bend the ion beam without causing the beam to diverge (beam blow-up) at a significant angle.
However, when a conventional electrostatic deflector is used as a deceleration system to decelerate ions at a high deceleration rate downstream, it causes excessive ion focusing and the ion beam passes through downstream components. It turns out that it expands gradually. Beam blow-up leads to ion loss and becomes an impediment to the operation of the ion implantation system. Furthermore, the conventional ion implantation system requires a high voltage to use the focusing lens, which may cause temporary beam instability. For example, due to arc discharge, contamination in the form of neutralization of atoms / molecules through a charge exchange reaction has also occurred.
Several aspects solve these problems as described below.

In one embodiment, an ion comprising a deceleration system having a deceleration ratio of at least 2 and receiving an ion beam to decelerate the ion beam and an electrostatic deflector disposed downstream of the deceleration system to deflect the ion beam An infusion system is disclosed.
The electrostatic deflector is a first electrode pair disposed downstream of the deceleration system to receive the decelerated beam, the first electrode pair being spaced apart from each other so as to form an ion beam path therebetween. A second electrode pair disposed downstream of the first electrode pair, the second electrode pair being spaced apart from each other so as to form an ion beam path therebetween. A terminal electrode pair disposed downstream of the second electrode pair, the inner electrode being disposed apart from the second electrode pair so as to form an ion beam path therebetween. And an outer electrode.
The first electrode pair, the second electrode pair, and the terminal electrode pair can be independently applied with a voltage.
As an example, each of the electrodes of the terminal electrode pair is held lower than the voltage at which any electrode of the second electrode pair is held. In addition, each of the electrodes of the first electrode pair is held at a lower voltage than the electrodes of the second electrode pair.

  By way of example, the deceleration system can be, for example, in the range of about 5 to about 100, or in the range of about 10 to about 80, or in the range of about 20 to about 60, or in the range of about 30 to about 50. Provide a reduction ratio at.

  In one example, the inner electrode of each of the electrode pairs is held at a voltage lower than the voltage at which the outer electrode of each of the electrode pairs is held so as to deflect an ion beam of positively charged particles.

  The inner electrode and the outer electrode of the first electrode pair may form a predetermined angle with respect to each electrode of the second electrode pair. Further, the inner electrode and the outer electrode of the terminal electrode pair may form a predetermined angle with respect to each electrode of the second electrode pair.

In one example, the first electrode pair and the outer electrode of the end electrode pair are held at a _first voltage (V ₁ ), and the inner electrode of the first electrode pair and the end electrode pair is set to a second voltage ( V ₂ ).
Further, the inner electrode of the second electrode pair is electrically grounded, and the outer electrode of the second electrode pair is held at a _third voltage (V ₃ ). The voltages _{V 1} is higher than the voltage _{V 2} voltage.
As an example, the voltage V ₁ ranges from about 0V to about −30 kV, V ₂ ranges from about 0V (zero volts) to about −30 kV (minus 30 kV), and the voltage V ₃ ranges from about 0V to about +30 kV. Range.

  In some embodiments, the ion beam is a ribbon ion beam, and in other embodiments, it is a circular beam.

  In one example, the ion beam received by the deceleration system has an ion energy in the range of about 10 keV to about 60 keV, for example in the range of about 10 keV to about 20 keV. The ion current is in the range of about 0.1 mA to about 40 mA, for example, in the range of about 5 mA to about 40 mA.

In one example, the deceleration system includes a deceleration element that is separated from a downstream focusing element, so that a gap is formed between the focusing element and the deceleration element.
This deceleration system may have two opposing electrode portions of the same voltage that are separated from each other, and a slot for providing an ion beam path therebetween.
The focusing element may have two separated electrode portions of the same voltage, and a slot for providing an ion beam path therebetween.
As an example, the separated electrode portions of the deceleration element and the focusing element may be connected at their upper and lower ends to form, for example, a square electrode. The electrodes of the deceleration element and the focusing element are held at different voltages so as to create an electric field in the gap to decelerate the received ion beam. This electric field will also focus the ion beam as it passes through the gap.

  The ion implantation system is disposed with an ion source that produces an ion beam and downstream of the ion source and upstream of a deceleration system and receives the ion beam from the ion source to produce a mass-selected ion beam. An analysis magnet may be provided.

As related aspects, the following ion implantation system is also disclosed. The ion implantation system is disposed downstream of the first electrode pair having a first electrode pair having an inner electrode and an outer electrode that are spaced apart from each other so as to form a path for an ion beam therebetween, and between the first electrode pair A second electrode pair having an inner electrode and an outer electrode spaced apart from each other so as to form a beam path; and a second electrode pair disposed downstream of the second electrode pair and spaced apart from each other so as to form an ion beam path therebetween. And a terminal electrode pair having an inner electrode and an outer electrode disposed in a row.
Each of the electrodes of the terminal electrode pair is held lower than the voltage at which any electrode of the second electrode pair is held, and each of the electrodes of the first electrode pair is compared with the electrode of the second electrode pair. At a lower voltage. Furthermore, the inner electrode of each of the first electrode pair, the second electrode pair, and the terminal electrode pair is held at a voltage lower than the voltage at which the outer electrode of each of the electrode pairs is held.

In some embodiments of the ion implantation system, the first electrode pair and the outer electrode of the end electrode pair are held at a _first voltage (V ₁ ), and the first electrode pair and the end electrode pair The inner electrode is held at a _second voltage (V ₂ ).
Further, the inner electrode of the second electrode pair is electrically grounded, and the outer electrode of the second electrode pair is held at a _third voltage (V ₃ ). The voltages _{V 1} is higher than the voltage _{V 2.}
As an example, voltage V ₁ ranges from about 0V to about −30 kV (minus 30 kV), V ₂ ranges from 0V to about −30 kV, and voltage V ₃ ranges from about 0V to about +30 kV. .

In one example, the ion implantation system may include a split lens disposed downstream of the electrostatic deflector.
The split lens includes a first electrode pair having a curved downstream end face and a second electrode pair having a curved upstream end face, and the end faces of the two electrode pairs are separated from each other with a gap therebetween. May be formed. The first electrode pair and the second electrode pair can each independently apply a voltage. For example, a voltage is applied to the first electrode pair and the second electrode pair so as to generate an electric field in the gap for focusing an ion beam passing through the split lens.

As another aspect, the following ion implantation system is disclosed. The ion implantation system includes an electrostatic deflector that receives and deflects an ion beam, and a split lens disposed downstream of the electrostatic deflector.
The split lens includes a first electrode pair having a curved downstream end face and a second electrode pair having a curved upstream end face, and the end faces of the two electrode pairs are separated from each other with a gap therebetween. May be formed.
For example, the first electrode pair and the second electrode pair can independently apply a voltage so as to generate an electric field in the gap for focusing an ion beam passing through the split lens.
The ion implantation system includes a deceleration / acceleration system disposed upstream of the electrostatic deflector and a mass selector disposed upstream of the deceleration / acceleration system to receive the ion beam and produce a mass-selected ion beam. May be provided.
In one example, the electrostatic deflector includes a first electrode pair, a second electrode pair, and a terminal electrode pair, and an inner electrode disposed at a distance from each other, which can serve as an ion beam path therebetween. The outer electrode is provided with a gap. The three electrode pairs can be independently applied with voltages. For example, each of the electrodes of the terminal electrode pair is held lower than the voltage at which any electrode of the second electrode pair is held, and each of the electrodes of the first electrode pair is compared with the electrode of the second electrode pair. And held at a lower voltage.
In one example, the first electrode pair and the outer electrode of the end electrode pair are held at a _first voltage (V ₁ ), and the inner electrode of the first electrode pair and the end electrode pair is set to a second voltage ( V ₂ ). Here, the voltage V ₁ is higher than the voltage V ₂ .
Further, the inner electrode of the second electrode pair is electrically grounded, and the outer electrode of the second electrode pair is held at a _third voltage (V ₃ ).

  A better understanding of the various aspects of the present invention can be gained with reference to the following detailed description and accompanying drawings. Reference drawings are briefly described below.

It is the schematic which shows a ribbon ion beam. 1 is a schematic diagram illustrating an ion implantation system according to an embodiment of the present disclosure. FIG. FIG. 2D is a schematic diagram illustrating a correction system employed in the ion implantation system of FIG. 2A according to an embodiment of the present disclosure. 3 is a schematic side cross-sectional view of a portion of the correction system shown in FIG. 2B. FIG. 2 is a partial schematic view of an ion source for generating a ribbon ion beam. FIG. 3B is another partial schematic diagram of the ion source of FIG. 3A. FIG. 4 is another partial schematic diagram of the ion source of FIGS. 3A and 3B. FIG. FIG. 3 shows a current profile of an exemplary ribbon ion beam generated by an ion source based on the ion source described below in connection with FIGS. 3A-3C. FIG. 3 is a schematic diagram illustrating a correction system suitable for use in embodiments of the present disclosure. It is the schematic which shows the ribbon ion beam which passes the correction apparatus which concerns on embodiment of this indication. FIG. 6 is a schematic diagram illustrating a ribbon ion beam passing through a correction device according to an embodiment of the present disclosure, the correction device configured to apply a lateral electric field to at least a portion of the ion beam. FIG. 6 is a schematic diagram illustrating a ribbon ion beam passing through a correction apparatus according to an embodiment of the present disclosure, the correction apparatus being configured to apply a vertical electric field to the ion beam to cause deflection of the ion beam. Yes. It is the schematic which shows the gradient voltage for applying to the electrode pair of the correction apparatus shown to FIG. 7B. FIG. 6 is a schematic diagram showing a ribbon ion beam passing through a correction apparatus according to an embodiment of the present disclosure, the correction apparatus being configured to generate a longitudinal vibration motion of the ion beam. It is the schematic which shows the triangular voltage waveform for applying to the electrode pair of the correction apparatus shown to FIG. 8A. 2B is a partial schematic diagram of the ion implantation system shown in FIGS. 2A, 2B and 2C, further illustrating a beam profiler for measuring the current profile of the ion beam. FIG. FIG. 4 shows a simulated current profile of an uncorrected ribbon ion beam as a function of height. FIG. 10B is an exemplary voltage that can be applied to the electrode pair of one corrector of the ion implantation system shown in FIGS. 2A, 2B, and 2C to achieve a coarse correction of the beam profile shown in FIG. 10A. Also shown is a simulated current profile of a partially corrected beam obtained through such coarse correction. Exemplary voltages that can be applied to the electrode pairs of other correctors of the ion implantation system shown in FIGS. 2A, 2B, and 2C to improve the partially corrected beam uniformity shown in FIG. 10B. The figure also shows a simulated current profile of the corrected beam obtained by the method. 1 is a schematic diagram of an ion implantation system in which an electrostatic deflector having three electrode pairs is used as an example. FIG. FIG. 11B is a schematic partial view in a dispersion plane of the ion implantation system represented in FIG. 11A. FIG. 11B is a different schematic partial view in a non-dispersive plane of the ion implantation system represented in FIG. 11A. It is the schematic which shows the voltage source which applies a voltage to the electrode of an electrostatic deflector, and the controller which controls the voltage source. It is a figure showing the theoretical simulation result of the ion beam which passes through the deceleration system which is working with the reduction ratio of 60, and the downstream electrostatic deflector formed with two separate electrodes spaced apart. It is a figure showing the theoretical simulation result of the ion beam which passes the deceleration system in operation | movement with the reduction ratio of 60, and the downstream electrostatic deflector which consists of three electrode pairs. It is a figure showing the theoretical simulation result when the arsenic ion beam of the energy of 30 keV and the electric current value of 25 mA passes through the electrostatic deflector formed by the two electrodes. It is a figure showing the theoretical simulation result when an arsenic ion beam with an energy of 30 keV and a current value of 25 mA passes through an electrostatic deflector formed of three series electrode pairs. FIG. 2 is a partial schematic cross-sectional view of a dispersion plane of an ion implantation system having a split lens disposed downstream of an electrostatic deflector. FIG. 14B is a partial schematic side view of the ion implantation system represented in FIG. 14A on a non-dispersive surface. FIG. 2 is a partial schematic view of a dispersion surface of an ion implantation system using an electrostatic deflector composed of three electrode pairs and a split lens disposed downstream thereof.

  In some aspects, the present disclosure provides an ion implantation system (also referred to herein as an ion implanter) that includes an ion source for generating a ribbon ion beam, and a ribbon ion beam that is incident on a substrate on which the beam is incident. It is directed to a correction system to ensure that it exhibits a substantially uniform current density profile at least along its longitudinal dimension in position. In some cases, the correction system may include a ribbon ion beam drawn from the ion source in addition to other optics in the ion implantation system beamline while the ribbon ion beam is transported to the substrate for ion implantation. It may be employed to substantially maintain the profile of the ribbon ion beam (eg, within a range of about 5% or better).

  In some embodiments, an ion implantation system according to the present disclosure includes a beamline having two stages. That is, a beam implanter stage followed by a beam correction stage, the latter also optionally including a mechanism for decelerating or accelerating the ion beam. The beam injector stage may include beam generation and mass selection. In some embodiments, the beam correction stage may include a correction array in addition to the deceleration / acceleration optics. In some embodiments, the beamline may inject ions into a 300 mm substrate (eg, by a ribbon ion beam having a height of about 350 mm) or a 450 mm substrate (eg, by a ribbon ion beam having a height of about 500 mm). It can also be configured. For example, the beam line may include replaceable ion optics components to accommodate different substrate dimensions. The ion optics component includes, for example, a replacement end effector in an ion implantation end station and a substrate handling element such as a FOUP (front open integration pod), as well as an extraction electrode for extracting an ion beam from an ion source, a correction Arrays and deceleration / acceleration stage optics may be included.

  Various exemplary embodiments of the present disclosure are described below. Terms used in the description of these embodiments have their ordinary meaning in the art. The following terms are defined for clarity.

  As used herein, the term “ribbon ion beam” is an aspect ratio defined as the ratio of its largest dimension (also referred to herein as the longitudinal dimension of the beam) to its smallest dimension (also referred to herein as the transverse dimension of the beam). The aspect ratio is at least about 3, such as 10 or more, or 20 or more, or 30 or more. Ribbon ion beams can exhibit a variety of different cross-sectional profiles. For example, the ribbon ion beam may have a rectangular or elliptical cross-sectional profile.

  FIG. 1 schematically illustrates an exemplary ribbon ion beam 8 having a longitudinal dimension (also referred to herein as height) H and a lateral dimension (also referred to herein as width) W. Without loss of generality, in the following description of various embodiments of the present invention, the ion beam travel direction is such that its longitudinal dimension is along the Y axis of the Cartesian coordinate system and its transverse dimension is along the X axis. Therefore, it is assumed to be along the Z axis. As described in more detail below, in many embodiments, analysis magnets are employed to disperse the ion beam in a plane perpendicular to its direction of travel. This plane is referred to herein as the dispersion plane. In the following embodiments, the dispersion surface corresponds to the XZ plane. A plane perpendicular to the dispersion surface is called a non-dispersion surface. In the following embodiments, the non-dispersed surface corresponds to the YZ plane.

  The term “current density” is used herein in line with its use in the art to describe the current associated with ions flowing through a unit area, eg, a unit area perpendicular to the direction of ion travel.

  As used herein, the term “current density profile” refers to the ion current density of a beam as a function of position along the beam. For example, the ion current density along the longitudinal dimension of the beam is the ion current density as a function of distance from a reference point (eg, the top, bottom, or center of the beam) along the longitudinal dimension of the ion beam, or It represents the current associated with the ions flowing through the unit length along the dimension.

  The term “substantially uniform current density profile” refers to an ion current density profile that exhibits at most 5% RMS deviation.

  2A, 2B, and 2C, an ion implantation system 10 according to an embodiment of the present disclosure facilitates an ion source 12 that generates a ribbon ion beam 8 and extraction of the ion beam from the ion source. And an extraction electrode 14 that is electrically biased. The suppression electrode 16 is electrically biased so as to suppress the backflow of neutralized electrons (for example, electrons generated through neutralization of the surrounding gas by the ion beam) to the ion source. The focusing electrode 18 is electrically biased to reduce ion beam divergence. The ground electrode 19 defines a reference ground for the ion beam. The analysis magnet 20 disposed on the downstream side of the focusing electrode 18 receives the ribbon ion beam 8 and generates a mass-selected ion beam.

  In some embodiments, the ion source housing and analysis magnet frame assembly may be electrically isolated from ground potential. For example, they may be floated below ground potential, for example to -30 kV. In some cases, the floating voltage may be selected to extract the ion beam from the ion source and perform mass analysis at an energy higher than that at the location of the substrate on which the ion beam is incident for ion implantation. good. Alternatively, the ion beam may be extracted from the ion source and mass analyzed and then accelerated so that it enters the substrate at a higher energy.

  2A-2C, a typical ion implantation system 10 adjusts the current density profile along at least the longitudinal dimension of the ribbon ion beam 8 (eg, the dimension at the non-dispersed surface of the ion beam) to at least the longitudinal dimension. A correction system 22 is further included for generating an output ribbon ion beam that exhibits a substantially uniform current density profile along the same. This is discussed in more detail below. Further, the correction system 22 adjusts the lateral dimension of the ion beam to reduce divergence along, for example, the lateral dimension of the ion beam (eg, the dimension at the dispersion surface) to ensure that the output ion beam has the desired dimension. Can be.

  In some embodiments, as discussed below, the correction system 22 can further achieve deceleration / acceleration of the mass-selected ribbon ion beam 8. In this way, an output ribbon ion beam having the desired energy and a substantially uniform current density profile can be obtained. Without loss of generality, in the embodiment discussed below, the correction system 22 is also referred to as a deceleration / acceleration system. However, it should be understood that in some embodiments, the correction system 22 may not achieve any deceleration or acceleration of the ion beam.

  The exemplary ion implantation system 10 further includes an end station 24 that includes a substrate holder 25 for holding the substrate 26 in the path of the ribbon ion beam 8 exiting the correction system 22. . The output ribbon ion beam 8 is incident on the substrate 26 and implants ions therein. In this embodiment, the substrate holder 25 is scanned along one dimension orthogonal to the direction of travel of the ion beam 8 in a manner known in the art to ionize different portions of the substrate to implant ions into the substrate. You may make it expose to a beam. In some embodiments, the longitudinal dimension of the ion beam 8 is greater than the diameter of the substrate 26 so that linear movement of the substrate along a dimension perpendicular to the direction of travel of the ion beam results in ion implantation across the substrate. Can be made. The substantial uniformity of the current density of the output ribbon ion beam ensures that a uniform dose of implanted ions is achieved across the substrate.

  A variety of different ion sources capable of generating a ribbon ion beam can be employed as the ion source 12. Some ion sources capable of generating a ribbon ion beam are described in US Pat. No. 6,664,547 entitled “Ribbon Beam Ion Source with Controllable Density Profile” and “Ions”. US Pat. No. 7,791,041 (the aforementioned patent document 2) entitled “Source, Ion Implantation Apparatus and Ion Implantation Method”, which is incorporated herein by reference in its entirety.

  The ion source 12 employed in this embodiment is described in detail in co-pending patent applications entitled “Ion Source” and “Magnetic Field Source for Ion Source” assigned to the assignee of the present application, These applications were filed concurrently with this application and are hereby incorporated by reference in their entirety. Briefly, with reference to FIGS. 3A, 3B, and 3C, the ion source includes two opposing external electron guns 28 disposed at opposite ends of an elongated rectangular ionization chamber 32 (ion source body). / 30 may be included. Each electron gun may include an indirectly heated cathode (IHC) 28a / 30a and an anode 28b / 30b. As shown in FIG. 3C, the plate-shaped plasma electrode 34 includes an opening shaped to allow extraction of ions from the ion source (for example, the opening may be a 450 mm × 6 mm slot). Ion extraction is aided by an extraction electrode 36 that is similar in shape to the plasma electrode 34, which is separated from the plasma electrode 34 by one or more electrically insulating spacers (not shown). In some embodiments, the extraction electrode 36 may be biased to −5 kV with respect to the ion source body 32 and the plasma electrode 34. With such a configuration, the ribbon ion beam 8 can be generated.

  Referring to FIG. 3B, the ion source body 32 is immersed in the axial magnetic field generated by the electromagnetic coil assembly 38. In this embodiment, the coil assembly 38 includes three secondary coils that are distributed along the major axis of the ion source body 32 and are independent and partially overlap. The generated magnetic field is generated at the top, middle and bottom of the ion source body 32. The magnetic field confines primary electrons generated by the electron guns 28, 30, thereby generating a well-bounded plasma column along the axis of the ionization chamber 32. The magnetic flux density generated by each of the three coil segments may be independently adjusted to ensure that the current density of the extracted ion beam is substantially non-uniform.

  Referring to FIG. 3C, five separate gas supplies 40a, 40b, distributed along the long axis of the ion source body 32, each having a flow regulator (MFC) for it. 40c, 40d and 40e may be used to adjust the ion density along the plasma column. In this embodiment, the anode and cathode of the electron guns 28 and 30 are made of graphite, as are the plasma electrode 34 and the extraction electrode 36. The ionization chamber 32 is made of aluminum, and its inner surface is covered with graphite.

  The extracted ion beam 8 can be analyzed by a retractable beam profiler located in the ion source housing. Illustratively, FIG. 4 shows the beam current of a ribbon ion beam generated by an ion source prototype as described above as a function of its vertical (vertical) position. The current density profile along the vertical dimension shows about 2.72% RMS non-uniformity.

  Referring again to FIG. 2A, in this embodiment, the ion beam 8 generated by the ion source 12 is extracted and accelerated to the desired energy (eg, 5 to 80 keV) before entering the analysis magnet 20. . The analysis magnet 20 applies a magnetic field on the non-dispersion surface to the ion beam 8 in order to separate ions having different mass-to-charge ratios on the dispersion surface, thereby constricting in the dispersion surface at the focal point of the analysis magnet 20. A mass-selected ion beam is generated. As discussed below, a variable size mass analysis slit 20a located near the beam constriction allows ions having a desired mass to charge ratio to pass downstream toward other elements of the ion implantation system. Make it possible to do. This is discussed in more detail below.

  Various analysis magnets known in the art can be utilized. In this embodiment, the analysis magnet 20 has a saddle coil design with a pole gap of 600 mm, a bending angle of about 90 degrees and a bending radius of 950 mm, although other pole gaps, bending angles and bending radii are also possible. It can also be used. The variable size mass analysis slit 20a that is placed allows ions of the desired mass to charge ratio to pass downstream toward the deceleration / acceleration system 22. In other words, the analysis magnet 20 generates a mass-selected ribbon ion beam that is received by the deceleration / acceleration system 22.

  With continued reference to FIGS. 2A, 2B, and 2C, the deceleration / acceleration system 22 includes a slot 40 for receiving a mass-selected ribbon ion beam. The slot 40 is sufficiently high to accommodate the longitudinal dimension of the ion beam (eg, in some instances, the slot 40 is 600 mm high) and within a selected range (eg, about 5 mm to about 60 mm). (Between) and a continuously variable lateral dimension (for example, a dimension on a dispersion surface).

  A correction device 42 is arranged downstream of the slot 40 for receiving the ribbon beam 8 passing through the slot 40. In this embodiment, as schematically shown in FIG. 5, the correction device 42 comprises a plurality of electrode pairs E 1 stacked and spaced along the longitudinal dimension of the ion beam 8 (ie along the Y axis), Including E2, E3, E4, E5, E6, E7, E8, E9 and E10, and each electrode pair can be independently electrically biased. More specifically, in this embodiment, electrostatic voltage sources V1, V2, V3, V4, V5, V6, V7, V8, V9, and V10 apply independent voltages to each electrode pair, In order to locally deflect one or more portions, an electric field having a component along the longitudinal dimension of the ribbon ion beam 8 is generated to adjust the current density profile along the longitudinal dimension of the ion beam. In this embodiment, the adjustment of the current density profile as described above is performed to increase the uniformity of the current density along the longitudinal dimension of the ion beam (eg, in a non-dispersed plane). The voltage sources V1 to V10 may be independent voltage sources or different modules of a single voltage source.

  Each electrode pair includes two electrodes, such as electrodes E1a and E1b, which are arranged substantially parallel to a plane defined by the traveling direction of the ion beam 8 and its vertical dimension. The pair of electrodes are spaced apart to provide a lateral gap through which the ion beam can pass. The number of electrode pairs should be selected based on, for example, the longitudinal dimensions of the ion beam, the level of resolution required to correct non-uniformities in the longitudinal profile of the ion beam, and the type of ions in the ion beam. Can do. In some embodiments, the number of electrode pairs may be in the range of about 10 to about 30, for example.

  A controller 44 that communicates with the voltage sources V1-V10 is described below in order to locally deflect one or more portions of the ion beam passing between one or more electrode pairs at a selected angle. In the manner discussed in detail, the voltage (eg, electrostatic voltage) to be applied to the electrode pair of the corrector 42 can be determined, thereby adjusting the current density along the longitudinal dimension of the ion beam 8.

  As an example, FIG. 6 shows that three electrode pairs E5, E6 and E7 have electrostatic voltages applied to them such that the voltage applied to electrode pair E6 is greater than the voltage applied to electrode pairs E5 and E7. Biased by application, an electric field component indicated by an arrow is generated in a predetermined region, and a shaded portion of the ion beam 8 is passed through the region (this indicates that the charge density is higher than other portions of the ion beam). (In this example, the other electrode pairs are kept at ground voltage). The voltage applied to the shaded portion of the ion beam causes an upward deflection of the upper portion of the portion and a downward deflection of the lower portion of the portion, thereby causing a current along the longitudinal dimension. Reduce the charge density in the portion to improve the uniformity of the density profile.

  Referring to FIG. 7A, in this embodiment, the correction device 42 applies a lateral electric field (that is, an electric field having a component along the lateral dimension of the ion beam) to the ion beam 8, so that the lateral direction of the ion beam is increased. For example, the traveling direction of the ion beam may be changed so as to cause this deflection. More specifically, the correction device 42 may be configured such that each electrode of the electrode pair can be independently biased. For example, in this embodiment, each of the voltage sources V1 to V20 can apply an independent voltage (eg, electrostatic voltage) to the electrodes of the electrode pair (eg, the voltage sources V1 and V11 are applied to the electrode pair E1). (See that it is configured to apply independent voltages to the electrodes E1a and E1b).

  As an example, the voltage difference between opposing electrode pairs of one or more electrodes may be selected to achieve local lateral deflection of one or more portions of the ion beam 8. For example, as shown in FIG. 7A, in this example, voltage sources V2 and V12 apply different voltages v2 and v12 to electrodes E2a and E2b (v12 <v2) and pass between these opposed electrodes. A local deflection of the ion beam portion toward the electrode E2b is caused. At the same time, the voltage sources V4 and V14 apply different voltages v4 and v14 to the electrodes E4a and E4b (v14> v4), with respect to the part of the ion beam passing between these opposite electrodes, the electrode E4a. This causes a local deflection toward the. In some embodiments, the voltage difference between two opposing electrodes may be in the range of about 0V to about 4 kV.

  In some cases, the entire ion beam is applied to all electrodes on one side of the ion beam, for example, to change its direction of travel, and to all other electrodes on the other side It can also be deflected laterally by applying a voltage.

  With reference to FIGS. 7B and 7C, in some embodiments, the corrector 42 is configured to deflect the entire ion beam 8 along a longitudinal dimension (ie, perpendicularly along the Y axis). Also good. For example, as shown in FIG. 7C, the controller 44 causes the voltage sources V1 to V10 to apply a gradient voltage to the electrode pairs E1 to E10, so that an electric field having a component along the vertical dimension of the ion beam (FIG. (Schematically indicated by the arrow A1 in the figure) can be generated, thereby causing a longitudinal deflection of the ion beam.

  The controller 44 that communicates with the voltage sources V1 to V20 can determine the voltage to be applied to the electrodes, for example, based on the desired local or global deflection angle of the ion beam 8. The controller 44 can determine the required voltage in a manner known in the art, for example based on the charge of the ions in the ion beam and the desired deflection angle. In some cases, the controller 44 can perform the application of voltages to the electrodes of the electrode pair so as to achieve both lateral and longitudinal deflection of the ion beam. For example, the voltage difference between different electrode pairs can cause local longitudinal deflection, eg, in the manner discussed above in connection with FIG. 6, while the voltage difference between the electrodes of the electrode pair is , Local lateral deflection can occur.

  With reference to FIG. 8A, in some embodiments, the corrector 42 can cause the ion beam 8 to oscillate along its longitudinal dimension. The waveform generator 100 under the control of the controller 44 can apply a variable voltage to one or more electrode pairs in order to generate a variable electric field with a component along the vertical dimension of the ion beam (along the Y axis). Which can also cause time-varying deflection of the ion beam. In some cases, such time-varying deflection of the ion beam may be in the form of a periodic oscillation along its longitudinal dimension of the ion beam. In some cases, the amplitude of vibration as described above may be in the range of about 10 mm to about 20 mm, for example.

  As an example, the waveform generator 100 may apply a triangular voltage waveform to the electrode pairs E1 to E10, as schematically shown in FIG. 8B, in order to cause the ion beam 8 to generate periodic vibrations along its longitudinal axis. it can. Such “small oscillations” of the ion beam can improve the implantation uniformity of ions implanted into the substrate upon which the ion beam is incident. The frequency of vibration may be varied based on, for example, the speed at which the substrate is moved relative to the incident ion beam. In some embodiments, the vibration frequency may be in the range of about 1 Hz to about 1 kHz, for example.

  Referring again to FIGS. 2A, 2B, and 2C, the deceleration / acceleration system 22 further includes a deceleration / acceleration element 46 that is spaced apart from the downstream focusing element 48 and that defines a gap region 50. . The deceleration / acceleration element 46 includes two opposing equal voltage electrodes 46a and 46b, which provide a path therebetween for the passage of the ion beam 8. Similarly, focusing element 48 includes two equal voltage opposing electrodes 48a and 48b, which provide a path therebetween for the passage of ion beam 8.

  Application of a voltage difference between the deceleration / acceleration element 46 and the focusing element 48 generates an electric field in the gap region 50 for deceleration or acceleration of the ion beam. The voltage difference between the deceleration / acceleration element 46 and the focusing element 48 can be determined by those skilled in the art based on the desired change in ion energy, the type of ions in the ion beam, and the particular application in which the ion beam is utilized. You may select by a known method.

  By way of example, in some embodiments, a voltage in the range of about 0 to about −30 (minus 30) kV, or a voltage in the range of about 0 to about +30 kV is applied to the deceleration / acceleration electrodes 46a / 46b. Alternatively, a voltage within the range of about 0 to −5 (minus 5) kV may be applied to the focusing electrodes 48a / 48b.

  Referring to FIG. 2C, in this embodiment, one or both upstream sides (UF) of focusing electrodes 48a / 48b offset divergence (eg, along the longitudinal dimension of the ion beam) in the non-dispersive plane of ion beam 8. It is curved to generate an electric field component for the purpose in the gap region 50. Illustratively, FIG. 2C shows an ion beam 8 passing through a gap 50, which ion beam diverges near the longitudinal edges of its non-dispersed surface due to repulsive space charge effects. Showing. The curved shape of the upstream end (upstream side) of the focusing electrodes 48a / 48b applies a correction force to the diverging ions as described above to ensure substantially parallel travel of the ions in the ion beam. It may be configured to facilitate the generation of an electric field pattern. As an example, the upstream end of the focusing electrodes 48a / 48b may have a recessed shape (when viewed from the upstream direction) that typically has a radius of curvature in the range of about 1 m to about 10 m.

  Referring again to FIGS. 2A, 2B, and 2C, the deceleration / acceleration system 22 further includes an electrostatic deflector 52 that is disposed downstream of the focusing element 48 and is spaced apart by a gap 53 therefrom. Contains. The voltage difference between the focusing element 48 and the electrostatic deflector 52 (eg, one or more electrodes of the deflector 52) causes an electric field in the gap 53 to reduce divergence along the lateral dimension of the ribbon ion beam 8. Can be generated. In other words, the gap 53 between the focusing element 48 and the electrostatic deflector 52 functions as a focusing lens for reducing divergence along the lateral dimension of the ion beam 8. One or more voltage sources may be used to apply a voltage to the deceleration / acceleration element 46 and the focusing element 48 in a manner known in the art, for example under the control of the controller 44 described above.

  In this embodiment, the electrostatic deflector 52 has an outer electrode 52a and an inner electrode 52b opposite thereto, against which the ion beam 8 is passed through a lateral gap separating these electrodes. Different voltages can be applied to cause deflection of the ion beam during passage. As an example, the deflection angle of the ion beam may be in the range of about 10 degrees to about 90 degrees, more specifically 22.5 degrees.

  In this embodiment, the electrostatic deflector 52 further includes an intermediate electrode 52c, which is disposed downstream of the inner electrode 52b and is electrically insulated therefrom (eg, Through the gap), a voltage independent of the voltage applied to the inner electrode 52b can be applied to the intermediate electrode 52c. As an example, in this embodiment, the outer electrode 52a and the intermediate electrode 52c are kept at the same voltage. In some embodiments, the voltage applied to the outer electrode 52a may be in the range of about 0 to about −20 (−20) kV, and the voltage applied to the inner electrode 52b is about −−. It may be in the range of 5 (minus 5) kV to about −30 (minus 30) kV.

  The outer electrode 52a includes an upstream portion (UP) and a downstream portion (DP), which are arranged at an accurate angle with each other to impart a bending shape to the outer electrode 52a. The angle between the upstream and downstream portions of the outer electrode 52a is selected based on, inter alia, geometric limitations and lateral divergence as the ion beam enters the deceleration / acceleration system 22. Also good. In this embodiment, the angle between the upstream portion and the downstream portion of the outer electrode 52a is about 22.5 degrees. In this embodiment, the upstream portion and the downstream portion integrally form the outer electrode 52a. However, in other embodiments, the upstream portion and the downstream portion are electrically equivoltage. Separate electrodes connected in this manner may be used.

  As described above, the voltage difference between the outer electrode 52a and the inner electrode 52b generates an electric field for deflecting ions in the ion beam 8 in the space between these electrodes. Even if electrically neutral species (neutral atoms and / or molecules) are present in the ion beam 8, the neutral species are not deflected and they enter the electrostatic deflector 52. Continues along the direction of travel. As a result, these neutral species, or at least a portion thereof, are removed from the ion beam 8 by impacting the downstream portion (DP) of the outer electrode 52a.

  Another (second) correction device 54 for adjusting the current density along the longitudinal dimension of the ion beam 8 (in the non-dispersion plane) may optionally be arranged downstream of the electrostatic deflector 52. good. In this embodiment, the correction device 54 has the same structure as the upstream correction device 42. In particular, the correction device 54 includes a plurality of spaced electrode pairs, such as the electrode pairs shown in FIG. 5 in relation to the upstream correction device 42, the electrode pairs comprising each pair of electrodes. Are stacked along the longitudinal dimension of the ion beam with a lateral gap formed for the passage of the ion beam 8. Similar to the upstream correction device 42, each electrode pair of the second correction device 54 is connected to the voltage sources V1 to V10 shown in FIG. It may be configured to be individually biasable by a plurality of similar voltage sources. In this embodiment, the second corrector 54 can locally deflect one or more portions of the ion beam 8 to further improve the uniformity of current density along the longitudinal dimension of the ion beam 8. . In this way, the two correctors 42 and 54 jointly ensure that the ribbon ion beam 8 exiting the deceleration / acceleration system 22 exhibits a high degree of current density uniformity along its longitudinal dimension. .

  The controller 44 also communicates information with a voltage source that applies a voltage to the electrode pair of the second correction device 54. The controller 44 can determine the voltage to be applied to the electrode pair, for example in the manner discussed in more detail below, and causes the voltage source to apply the voltage to the electrode pair. be able to.

  Similar to the upstream correction device 42, the second downstream correction device 54 produces a lateral deflection of the ion beam 8 and / or an oscillating motion along the longitudinal dimension of the ion beam in the manner described above. It can also be configured. Further, the downstream corrector 54 can also be configured to produce a longitudinal (vertical) deflection of the entire ion beam, eg, in the manner discussed above in connection with the upstream corrector 42. it can.

  As described above, in this embodiment, the outer electrode 52a and the intermediate electrode 52c are kept at the same voltage. This improves, and preferably does, any disturbance of the ion beam 8 due to undesired electric field components as the ion beam 8 passes through the gap between the electrostatic deflector 52 and the second corrector 54. Can be prevented.

  In this embodiment, the electrode pairs of the second correction device 54 on the downstream side are arranged in a staggered pattern along the vertical dimension of the ion beam 8 with respect to the electrode pairs of the correction device 42 on the upstream side. In other words, each electrode pair of the correction device 54 is arranged perpendicularly to each electrode pair of the upstream correction device 42 (that is, along the longitudinal dimension of the ion beam) and shifted from the center. Such a deviation (offset) may be, for example, half of the vertical height of the electrode of the correction device (half pixel size). In this way, the correction devices 42 and 54 can produce local deflections of various parts of the ion beam 8 with a higher resolution, for example with a resolution corresponding to half-pixel dimensions.

  In this embodiment, the correctors 42 and 54 are sufficiently separated from each other to limit the voltage applied to their electrode pairs to less than about 2 kV, thereby improving the operational stability of the correctors. And can also allow close placement of electrode pairs along the longitudinal dimension.

  Although this embodiment employs two correctors 42, 54, other embodiments employ only a single corrector to improve current density uniformity along the longitudinal dimension of the ion beam. For example, either the correction device 42 or the correction device 54 may be employed. For example, in the embodiment in which the ion beam 8 received from the analysis magnet 20 is decelerated, only the downstream correction device 54 may be employed.

  With continued reference to FIGS. 2A, 2B, and 2C, another (second) focusing element 56 is optionally disposed downstream of the second corrector 54, the focusing element 56 being , Separated from the corrector 54 by a gap 58. Like the upstream focusing element 48, this second focusing element 56 includes a pair of opposing electrodes 56a and 56b, which provide a path between them for the passage of the ion beam 8. . The voltage difference between the one or more electrode pairs of the second corrector 54 and the second focusing electrode 56a / 56b can cause an electric field in the gap 58, which is caused by the ion beam 8 being a gap. Divergence along the transverse dimension of the ion beam as it passes through 58 can be reduced.

  In some embodiments, the voltage applied to focusing electrodes 56a and 56b may be in the range of about 0 to about −10 (−10) kV.

  The correction system further includes a ground element 60, which is disposed downstream of the second focusing electrodes 56 a and 56 b and separated from them to form a gap 62. It has a pair of opposing electrically grounded electrodes 60a and 60b. The opposing electrically grounded electrodes 60a and 60b form an electrically grounded duct through which the ion beam 8 exits the deceleration / acceleration system 22 toward the end station 24. doing.

  In some embodiments, the deceleration / acceleration system 22 does not have a second corrector 54 and a second focusing element 58.

  The voltage difference between the focusing electrodes 56a and 56b and the grounded electrodes 60a and 60b can generate an electric field component in the gap 62, which is generated when the ion beam 8 passes through the gap 62. Divergence along the lateral dimension of the ion beam can be reduced. Furthermore, in this embodiment, the upstream sides (upstream ends) of the electrodes 60a and 60b are separated from, for example, the upstream sides (upstream ends) of the electrodes 48a / 48b to reduce divergence along the longitudinal dimension of the ion beam 8. It is similarly curved. Accordingly, the lens gaps 58 and 62 jointly provide a second focusing lens for reducing divergence along the transverse and longitudinal dimensions of the ion beam 8.

  In many embodiments, the output ribbon ion beam exiting the deceleration / acceleration system 22 has an RMS non-uniformity of about 5% or less, or about 4% or less, or about 2% or less, more preferably less than 1%. 2 shows a current density profile along a vertical dimension having Such a ribbon beam can have a longitudinal dimension that is greater than the diameter of the substrate on which it is incident (eg, greater than about 300 mm or greater than about 450 mm). Thus, linear movement of the substrate along the lateral dimension can cause a substantially uniform implantation dose of ion implantation within the substrate.

In some embodiments, the output ribbon ion beam can also be used to implant an ion implantation dose in the range of about 10 ¹² to 10 ¹⁶ cm ^{−2 in} the substrate. In some such embodiments, the current of the ribbon ion beam incident on the substrate is, for example, in the range of tens of microamps (eg, about 20 microamps) to tens of milliamps (eg, about 60 milliamps), more specifically. Specifically, it may be in the range of about 50 microamperes to about 50 milliamperes, or in the range of about 2 milliamperes to about 50 milliamperes.

  In some embodiments, the voltage applied to the correctors 42 and 54 may be determined in the following manner. The current density of the mass-selected ribbon ion beam (also referred to herein as the uncorrected ion beam) exiting the analysis magnet 20 may be initially measured. For example, the uncorrected ion beam is decelerated / accelerated with the voltage applied only to the electrode of the electrostatic deflector 52 in order to guide the ion beam 8 to the end station 24 substantially in its original state. This can be achieved by passing it through.

  A current measurement device located in the end station 24 can be used to measure the current density profile of the uncorrected ion beam. As an example, FIG. 9 schematically illustrates a profiler 102 that is retractably disposed within an end station 24 of an ion implantation system. Various beam current profilers can be employed. For example, in this embodiment, the beam current profiler 102 may include an array of Faraday cups for measuring the beam current profile as a function of height. In other embodiments, the beam profiler may include an amperometric plate that can be moved across the ion beam. The beam profiler communicates with the controller 44 to provide information regarding the current profile along the longitudinal dimension of the ion beam 8. The controller 44 can use this information to determine the required voltage to be applied to the correction device and / or other elements (eg, focusing elements). For example, the controller 44 can use this information to determine the voltage to be applied to the electrode pairs of the corrector to improve the uniformity of the current density profile along the longitudinal dimension of the ion beam. .

  As an example, FIG. 10A shows a histogram representing simulated ion currents in several height values of an uncorrected phosphorus ion beam having an energy of 40 kV and a total current of 30 mA. This histogram shows the local non-uniformity of the ion beam relative to the uniformity window. In this example, the uncorrected beam exhibits an RMS variation of about 12.5% at different height value ion currents.

  Referring again to FIG. 9, the controller 44 can receive information from the beam profiler 102 regarding the current density profile of the uncorrected beam (eg, the information represented in the histogram above) and use that information as the correction Determine the voltage to be applied to one electrode pair in the device (eg, in the example described in connection with FIGS. 10A, 10B and 10C, the downstream correction device 54 is initially set). Can be used to achieve a first correction of the current density along the longitudinal dimension of the ion beam 8.

  In some embodiments, the controller 44 can compare the measured current in each height window to a reference value. When the difference between the measured current and the reference value exceeds a threshold value (for example, 1 or 2%), the controller 44 corresponds to one or more voltage sources, one or more electrode pairs, and the height window thereof. It is possible to apply a voltage to the electrode pair through which the beam portion to be passed passes to bring the current in the beam portion closer to the reference value. As detailed above, this can be achieved by creating a local deflection along the longitudinal dimension of the ion beam 8.

  As an example, the controller 44 applies the voltage shown in FIG. 10B to the voltage source connected to the electrode pair of the second correction device 54 to diverge the ion beam 8 at its center and focus at its upper end. It can be applied to a pair. For example, a voltage for reducing the current density in the beam portion can be applied to an electrode pair through which the beam portion corresponding to a height window of 60-90 mm passes. By such a method, the uniformity of the current density of the ion beam 8 can be improved.

  The partially corrected current density profile of the ion beam that is subject to correction by one of the correction devices (eg, the downstream correction device 54 in this example) is then related to, for example, measurement of the current density of the uncorrected ion beam. Thus, it can be measured by the method described above.

  As an example, the histogram shown in FIG. 10B has a height along the longitudinal dimension of the ion beam obtained using only the second corrector 54 in order to improve the current density of the uncorrected beam shown in FIG. 10A. It represents the simulated ionic current as a function of the window. This partially corrected ion beam exhibits an RMS deviation of about 3.2% beam current within the uniformity window (improved compared to the 12.5% variation exhibited by the uncorrected beam). ) 10B and 10C, the array 1 is the first correction device 42, the array 2 is the second correction device 54, and the array voltage is the voltage applied to these electrode pairs.

  Referring again to FIG. 9, the controller 44 determines the voltage applied to the electrode pair of the upstream correction device 42 to partially correct the ion to further enhance the uniformity of the beam profile. Information about the current density profile of the beam can be received. In other words, the upstream correction device 42 can realize fine correction of the beam profile.

  As an example, FIG. 10C shows voltages that can be applied to the first corrector 42 to further enhance the uniformity of the beam profile within the uniformity window. This figure also simulates the ion beam when both the first corrector 42 and the second corrector 54 are employed to correct the non-uniformity of the uncorrected beam having the beam profile shown in FIG. 10A. A histogram showing the profile obtained is shown. This histogram shows that the correction effect of the combination of the two correction devices 42, 54 results in a current density profile having an RMS deviation of the ionic current within the uniformity window of about 1.2%. In other words, in this example, the correction effect of the combination of the two correction devices results in an order of magnitude improvement in the uniformity of the current density profile along the vertical dimension of the ion beam 8.

  In other embodiments, the upstream correction device 42 may be configured to provide a coarse correction of the current density profile of the ribbon beam 8 exiting the mass analyzer 20 and the downstream correction device 54 may be Thereafter, a finer correction of the current density profile of the ion beam 8 may be realized.

  As described above, the deceleration / acceleration system 22 can be configured in a variety of different ways. By way of example, in some embodiments, the deceleration / acceleration voltage is set to zero so that the deceleration / acceleration system 22 functions only as a correction system without causing acceleration and / or deceleration of ions in the ion beam. May be.

The ion implantation system according to the present disclosure can be employed for implanting various ions into various substrates. Examples of such ions, phosphorus, arsenic, ^{_{boron, BF 2, B 18 H x}} + and _C 7 _H ^{x +} including molecular ions, such as, but not limited thereto. Some examples of substrates include silicon, germanium, epitaxial wafers (such as polysilicon coating), silicon-on-insulator (SIMOX) wafers, ceramic substrates such as SiC or SiN, solar cells, and flat panel display manufacturing. Including but not limited to the substrate used. Some examples of substrate shapes include circular, square or rectangular.

In some embodiments, the electrostatic deflector is implemented by arranging three pairs of series electrodes downstream of the deceleration / acceleration system.
As described in detail below, this electrostatic deflector implementation is particularly advantageous when the deceleration / acceleration system is operated in a deceleration mode with a reduction ratio of 2 or greater. This reduction ratio takes a value in the range of about 5-100. The term reduction ratio used here means the following ratio. That is, the ratio of the energy of the ion beam entering the deceleration system to the energy of the ion beam exiting the deceleration system. (Ie, the ratio of the ion beam energy received by the deceleration system to the energy of the decelerated ion beam).

FIGS. 11A, 11B and 11C schematically represent an ion implantation system 1100 according to such an implementation.
As described in detail below, this ion implantation system 1100 is based on FIGS. 2A, 2B, and 2C, except for the implementation of an electrostatic deflector comprised of three pairs of electrostatically deflected electrodes. Very similar to the ion implantation system 10 described. More specifically, it is similar to the ion implantation system 10 described above in the following points. The ion implantation system 1100 prevents an ion source 12 that generates an ion beam, an extraction electrode 14 that is electrically biased to facilitate extraction of the ion beam from the ion source, and backflow of neutralized electrons. A suppression electrode 16 electrically biased for the purpose, a focusing electrode 18 electrically biased to reduce the divergence of the ion beam, and a ground electrode 19 for defining a reference ground voltage for the ion beam. Is included. The analysis magnet 20 is disposed downstream of the focus electrode 18 and receives a ribbon ion beam and produces a mass-selected ion beam.

  The ion implantation system 1100 further includes a deceleration / acceleration system 200. The deceleration / acceleration system 200 includes a slot 202 for receiving a mass-selected ion beam and a correction device 204 similar to the correction device described above. Further, the deceleration / acceleration system 200 includes a deceleration / acceleration element 206. The deceleration / acceleration element 206 is separated from the downstream focusing element 208 and forms a gap 210 with the focusing element 208. As described above for the ion implantation system 10, the deceleration / acceleration element 206 includes two opposite-potential equipotential electrode portions 206a and 206b, and a slot serving as an ion beam path between the equivalent potential electrode portions 206a and 206b. Is forming. In this specific example, the electrode portions 206a and 206b are connected at the upper and lower ends to form a rectangular electrode. Similarly, the focusing element 208 includes two opposite-potential equipotential electrode portions 208a and 208b, and a slot serving as an ion beam path is formed between the equivalent potential electrode portions 208a and 208b.

  By applying a voltage difference between the deceleration / acceleration element 206 and the focusing element 208, an electric field is created in the gap region 210 to decelerate or accelerate the ion beam. In this specific example, during operation in the deceleration mode, the voltage difference generated between the deceleration / acceleration element 206 and the focusing element 208 can decelerate the ion beam passing through the gap 210, and the reduction ratio is Is at least 2. The reduction ratio is generally in the range of 5-100. As an example, to achieve such a deceleration ratio, a voltage in the range of about −60 kV to −5 kV is applied to the electrode portions 206a and 206b of the deceleration / acceleration element 206, and the electrode portion 208a of the focusing element 208 is applied. And 208b are applied with a voltage in the range of about 0 V to −30 kV (minus 30 kV).

  In this specific example, an electrostatic deflector 212 (hereinafter also referred to as E-bend 212) composed of three electrode pairs (214, 216 and 218) is disposed downstream of the focusing element 208 and receives an ion beam. To deflect. Even if the ion beam contains electrically neutral species (neutral atoms and molecules), these remain as they enter the electrostatic deflector and continue in the direction of propagation up to that point. , Will not be deflected. Similar to the previous embodiment, the electrostatic deflector can deflect the ion beam to an angle in the range of about 10 degrees to about 90 degrees (eg, 22.5 degrees).

The first electrode pair 214 includes an inner electrode 214b and an outer electrode 214a that are arranged apart from each other, and an ion beam passage is provided between the inner electrode 214b and the outer electrode 214a. The second electrode pair 216 also includes an inner electrode 216b and an outer electrode 216a that are arranged apart from each other, and an ion beam passage is provided between them. Similarly, the terminal electrode pair 218 also includes an inner electrode 218b and an outer electrode 218a that are arranged apart from each other, and an ion beam passage is provided between them.
Each electrode of the second electrode pair is disposed at an angle that is half the maximum deflection angle of the ion beam (for example, in the range of 5 degrees to 45 degrees) as compared with the electrodes of the first electrode pair and the terminal electrode pair. .
Thus, the electrostatic deflector of the present embodiment is disposed downstream of the deceleration system to receive the decelerated beam, and the inner electrode and the outer electrode are spaced apart from each other so as to form a path for the ion beam therebetween. A second electrode pair having an inner electrode and an outer electrode disposed downstream of the first electrode pair and spaced apart from each other so as to form an ion beam path therebetween, A terminal electrode pair having an inner electrode and an outer electrode disposed downstream of the second electrode pair and spaced apart from each other so as to form an ion beam path therebetween is provided.

As described in more detail below, the voltage of the electrodes of the first electrode pair 214 is held at a voltage lower than the voltage at which the electrodes of the second electrode pair 216 are held. Further, each of the electrodes of the terminal electrode pair 218 is held at a lower voltage than any electrode of the second electrode pair 216. Furthermore, in this embodiment, the ion beam contains positively charged ions, and the inner electrode of each electrode pair is held at a lower voltage than the corresponding outer electrode of the pair and passes through the space between the electrodes. This creates an electric field that bends the ion beam. In other words, the inner electrode 214b is held at a lower voltage than the outer electrode 214a, the inner electrode 216b is held at a lower voltage than the outer electrode 216a, and the inner electrode 218b is held at a lower voltage than the outer electrode 218a.
Thus, each of the electrodes of the terminal electrode pair is held lower than the voltage at which any electrode of the second electrode pair is held, and each of the electrodes of the first electrode pair is held by the electrode of the second electrode pair And the inner electrode of each of the first electrode pair, the second electrode pair, and the terminal electrode pair is more than the voltage at which the outer electrode of each of the electrode pairs is held. It is held at a low voltage.

More specifically, referring to FIG. 11B, in this embodiment, the outer electrode 214a of the first electrode pair 214 and the outer electrode 218a of the terminal electrode pair 218 are held at the same voltage (V ₁ ), and the first electrode pair The inner electrode 214b of 214 and the inner electrode 218b of the terminal electrode pair 218 are held at the same voltage (V ₂ ). Voltage _{V 2} is lower than the voltage _{V 1.} For example, the voltage _{V 2} is -25 kV, voltages _{V 1} becomes -15 kV. Further, the inner electrode 216b of the second electrode pair 216 is the outer electrode 216a of the second electrode pair are electrically grounded is held at a voltage _{V 3.} Here, voltage _{V 3} is higher than each of the voltages _{V 1} and the voltage _{V 2.}

As an example, voltage V ₁ ranges from about 0 V (zero volts) to −20 kV, and voltage V ₂ ranges from about 0 V (zero volts) to −30 kV. Further, the voltage _{V 3} is in the range from about 0 + 30 kV.

Referring to FIG. 11D, in this embodiment, voltage source 221 applies voltage V ₁ to electrodes 214a and 218a, voltage source 223 applies voltage V ₂ to electrodes 214b and 218b, and voltage source 225 is voltage applying a V ₃ to the electrode 216a. In other embodiments, the voltage source can apply different patterns of voltage to each electrode. The controller 227 can control each voltage source in order to apply a desired voltage to each electrode.
In this way, each of the electrode pairs can be independently applied with a voltage.

  As described herein, the arrangement of these three electrode pairs (214, 216 and 218) can provide advantages when used downstream of a deceleration system in an ion beam line. In particular, when the deceleration system is operated to provide a high deceleration ratio (eg, when the deceleration ratio is greater than about 2), it is powerful when the ion beam passes through the deceleration gap (eg, gap 210 described above). Receives a converging effect. Such strong focusing creates an overfocused beam. The overfocused beam will cause significant divergence (blow-up) as it passes through the downstream electrostatic deflector and will impact the curved path or other downstream component electrodes.

  By using segmented electrode pairs 214, 216 and 218 as electrostatic deflectors, this problem can be mitigated. More particularly, the segmented electrode pairs 214, 216 and 218 can exhibit a strong focusing force for high divergence caused by the focusing of a strong beam by this deceleration system. This ensures that the beam exits the electrostatic deflector. The beam can then go to the deflector electrode or downstream part and reach the downstream wafer without significant or preferably no loss of ions. For example, when entering the gap 213 between the first and second electrode pairs, the ion beam is defocused (blurring means the opposite effect of focusing, and so on). To do. When the ion beam enters the space between the second electrode pair 216 and the gap 215 between the second electrode pair 216 and the terminal electrode pair, the ion beam experiences a strong focusing force, but in some cases Then, although the beam is small, the gap 215 may be subjected to a force for blurring.

As a further example, FIG. 12A represents a theoretical simulation of the path of an ion beam passing through a deceleration system and a conventional electrostatic deflector formed by an electrode spaced between the two downstream. Yes. Specifically, in this simulation, the deceleration system includes two electrode pairs 1200 and 1201, with electrode pair 1200 maintained at a voltage of −29.5 kV and electrode pair 1201 maintained at a voltage of −5 kV. Yes. Further, the inner electrode 1202 of the electrostatic deflector is maintained at a voltage of −0.75 kV, and the outer electrode 1203 of the electrostatic deflector is maintained at a voltage of −0.47 kV. Further, it is assumed that the beam entering the deceleration system includes ions that are positively charged with energy of 30 keV. The energy of the beam was reduced to 0.5 keV by the path of the ion beam passing through this deceleration system. In other words, the deceleration system exhibited a deceleration ratio of 60.
The simulation results show that this high reduction ratio results in overfocusing of the beam at focal point A, which indicates that the beam is crossover and therefore diverges sufficiently fast that, as with downstream components, electrostatic deflection It will abut against the outer electrode at the end of the vessel.

In contrast, FIG. 12B represents a theoretical simulation of the path of an ion beam through a deceleration system downstream with an electrostatic deflector mounted with three downstream pairs of spaced electrodes. Similar to the previous simulation, this deceleration system is composed of two electrode pairs 1200 and 1201 held at voltages of -29.5 kV and -5.5 kV, respectively.
In this simulation, the electrostatic deflector is implemented by employing three electrode pairs 1204, 1205 and 1206 in the manner described above, and the inner electrode of the first electrode pair and the terminal electrode pair 1204 and 1206 is −0. The outer electrode is held at a voltage of -0.68 kV. The inner electrode of the second electrode pair is grounded and the outer electrode is held at a voltage of +0.73 kV.
Similar to the previous simulation, an ion beam with an energy of 30 keV entered the deceleration system and exited the deceleration system with a reduced energy of 0.5 keV (corresponding to a reduction ratio of 60). Although the high deceleration ratio results in overfocusing of the ion beam and hence divergence entering the electrostatic deflector is similar to the previous simulation, the electrostatic deflector in this example modifies the divergence so that the beam is ionized. Without any loss, it is possible to exit the curved path in the same manner as the downstream part and reliably go to the electrode of the curved path and the downstream part.

  As indicated above, another advantage of an electrostatic deflector implemented using three electrode pairs is that it helps to focus a high current ion beam. In an electrostatic deflector in which a high voltage is applied to an electrode on a curved path, there is typically a problem of insufficient background electrons in the curved path. Such electron deficiency makes it difficult to neutralize the charge of the beam, which suppresses the blow-up of the beam.

In particular, in conventional electrostatic deflectors, blow-up problems have been noted with high energy beams, for example, high energy above about 30 keV. The voltage of the high current beam required to supply an electrostatic deflector with sufficient focusing power is very high (eg, from -30 kV to -60 kV).

  For example, FIG. 13A shows a simulation of an ion beam of 30 keV energy and 25 mA current passing through a conventional electrostatic deflector 1300. In the electrostatic deflector 1300, the inner electrode 1300a is maintained at a voltage of −25 kV, and the outer electrode 1300b is maintained at a voltage of −12 kV. The beam width on the downstream wafer was 169 mm. Simulation results show that beam blowup causes ion losses similar to beam spot expansion on downstream wafers. This necessitates overscanning of the wafer and leads to a reduction in process throughput.

  In contrast, FIG. 13B shows a simulation of an ion beam of 30 keV energy and 25 mA current passing through an electrostatic deflector according to the present invention. This electrostatic deflector is composed of three electrode pairs 1302, 1304, and 1306, in which the inner electrodes of the electrode pairs 1302 and 1306 are held at a voltage of −25 kV, and the outer electrode paired therewith is −13. It is held at a voltage of 65 kV. The inner electrode of the electrode pair 1304 is grounded, and the outer electrode is held at a voltage of +16 kV. The simulation results show that an electrostatic deflector consisting of three separate electrode pairs prevents beam blow-up and allows the beam to pass through the curved path and downstream components without ion loss.

Referring to FIGS. 11A, 11B and 11C again, in this embodiment, the electrode 218a has an inner electrode portion 219 disposed on the downstream side of the inner electrode 218b, and the inner electrode portion 219 is electrically Insulated (eg, via a gap).
In this specific example, the inner electrode portion 219 is coupled to the outer electrode portion of the electrode 218a at the upper and lower ends to form a complete rectangular outlet electrode. This exit electrode forms a substantially uniform voltage space around the edge of the ribbon beam at the exit of the electrostatic deflector to maintain the ribbon shape of the beam. The ion implantation system 1100 further includes another optional correction device 220, which is arranged downstream of the electrostatic deflector to measure the current density in the dimension axis along the longitudinal direction of the ion beam. Adjustments are made (in the non-dispersive plane). Another focusing element 222 is also optionally arranged downstream of the second correction device.
The ion implantation system further includes electrode portions 224a and 224b that form a duct 224 that is electrically grounded, and the electrode portions 224a and 224b are disposed facing each other and are grounded. The ion beam passes through this duct 224 and enters the end station 226 where the wafer 228 is held to be irradiated with the ion beam.

By the way, the use of an electrostatic deflector comprising three separate electrode pairs is not limited to an ion implantation system in which a ribbon beam is used. Rather, such electrostatic deflectors can be utilized downstream of a deceleration system in other ion implantation systems that use a circular beam.
Another aspect of the present invention is the use of a split lens as an exit lens located downstream of an electrostatic deflector in an ion implantation system.

  As an example, FIGS. 14A and 14B are partial schematic views of an injection system 300. Similar to the implantation system 10 described above, the implantation system 300 includes an aperture 302 that receives a mass-selected ion beam from an upstream mass analyzer (not shown). The ion implantation system 300 includes a correction device 304, a deceleration / acceleration system 306 disposed downstream of the correction device 304, and an electrostatic deflector 308 disposed downstream of the deceleration / acceleration system. In this embodiment, the electrostatic deflector includes a curved outer electrode 308a and a curved inner electrode 308b, and a voltage difference is generated between these electrodes to generate an electric field therebetween and pass between the electrodes. The ion beam to be bent is bent.

Unlike the ion implantation system 10 described above, in this embodiment, a split lens 310 is disposed downstream of the electrostatic deflector 308.
The split lens 310 includes an electrode pair 312 and an electrode pair 314. The electrode pair 312 has a curved downstream end face 312a, and the electrode pair 314 has a curved upstream end face 314a.
The two curved end faces of the electrode pair are separated from each other by a curved gap 316 therebetween.
In a given implementation, each curved end face of lenses 312 and 314 is characterized by its radius of curvature (eg, indicated as R1 for electrode pair 312) in the range of about 250 mm to about 1000 mm. Is done.

The electrode pairs 312 and 314 can be independently biased to different voltages.
For example, voltage V ₁ can be applied to electrode pair 312 and different voltage V ₂ can be applied to electrode pair 314. Assuming that voltage V ₁ and voltage V ₂ are
Voltage V ₁ > Voltage V ₂
If so, a strong lens is formed that blurs in the vertical direction. On the other hand,
Voltage V ₁ <voltage V ₂
Then, a strong lens that focuses in the vertical direction is formed.
As an example, the voltage V ₁ and the voltage V ₂ are in a range from about 0 V to about −20 kV.
In certain implementations, even when the electrodes of the electrostatic deflector are held at a high voltage, the voltages V ₁ and V ₂ are approximately close to the ground voltage (eg, in the range of about 0 V to about −5 kV). It is also possible to select.
This helps to reduce, and preferably remove, energy contamination when the ion implantation system is operated in a deceleration mode.
As described above, the split lens includes the first electrode pair having the curved downstream end face and the second electrode pair having the curved upstream end face, and the first electrode pair and the second electrode pair are independent from each other. Thus, a voltage can be applied, and the end faces of the two electrode pairs are separated from each other to form a gap therebetween.
In addition, a voltage is applied to the first electrode pair and the second electrode pair so as to generate an electric field in the gap for focusing an ion beam passing through the split lens.

  More specifically, in the case where a normal lens rather than a split lens is employed downstream of the electrostatic deflector, a high energy ion beam (eg, an ion beam having an energy in the range of about 30 keV to 60 keV) is longitudinally In order to provide the focusing force, it may be necessary to apply a high voltage to the electrode of the lens. Such a high voltage can cause a temporary increase in the energy of the beam passing through the lens. Then, while passing through the lens, a specific ion may be subjected to a charge exchange reaction. Such charge exchange reactions may form neutral atoms / molecules. This neutral atom / molecule is injected into the downstream wafer. This is because the lens is generally arranged on the line of sight with respect to the wafer. In addition, the application of a high voltage to the lens electrode causes an arc discharge, thereby causing a temporary unstable state of the beam.

A split lens, such as the lens 310 described above, further reduces the instability of the beam due to arcing as well as beam contamination due to the generation of neutral atoms / molecules, and preferably eliminates the longitudinal instabilities in the electrostatic deflector. The direction focusing ability can also be improved. For example, the radius of curvature of the end face of the split lens electrode can be made sufficiently small (to the beam height) to allow for longitudinal focusing and blurring of the ion beam at very low lens voltages. Depending on the range of about 250 mm to about 500 mm, for example, a 300 mm high beam has a radius of curvature of about 450 mm). As an example, for a 60 keV beam, voltage V ₁ will be approximately −10 kV and voltage V ₂ will be 0V. This is well below the voltage required to achieve a similar focusing effect in a system utilizing conventional lenses.

  14A and 14B that follows, optionally, a correction device 317 may be positioned downstream of the split lens 310 to adjust the current density in the longitudinal axis of the ion beam (in a non-dispersive plane). Another focusing element 318 may optionally be arranged downstream of the second correction device. The ion implantation system further includes a grounded electrode 320 that forms an electrically grounded duct. The ion beam passes through this duct and enters an end station (not shown) where the wafer is held for ion beam irradiation.

  Another advantage of using the split lens 310 is that it allows space charge neutralization to occur immediately after the correction device 317. In contrast, in systems where a conventional lens (eg, lens 318) is utilized rather than the split lens 310, the starting position of the space charge neutralized beam transport goes deep into the grounded duct electrode 320. May move, thereby causing high current beam blow-up.

The split lens of the present invention, for example, the split lens 310 described above, can be employed downstream of an electrostatic deflector including three electrode pairs, such as the electrostatic deflector 212 described above.
As an example, FIG. 15 shows a partial schematic diagram of such an ion implantation system 400. The ion implantation system 400 includes a slit 402 for receiving an ion beam, a correction device 404, a deceleration / acceleration system 406, an electrostatic deflector 408 comprising three pairs of separation electrodes, a split lens 410, another It includes a correction device 412, a focusing electrode 414, and a grounded electrode 416 that provides a duct as a beam entrance to the end station where the wafer is held. The voltage applied to the electrodes of the electrostatic deflector 408 is similar to the range described above with respect to the electrostatic deflector 212.
In addition, this invention is applicable to an ion implantation system provided with an electrostatic deflector, and does not ask | require the presence or absence of a deceleration system. Accordingly, an ion implantation system comprising an electrostatic deflector for deflecting an ion beam, the first electrode pair having an inner electrode and an outer electrode spaced apart from each other so as to form a path for the ion beam therebetween, A second electrode pair having an inner electrode and an outer electrode disposed downstream of the first electrode pair and spaced apart from each other so as to form an ion beam path therebetween; and disposed downstream of the second electrode pair A pair of terminal electrodes having an inner electrode and an outer electrode spaced apart from each other so as to form an ion beam path therebetween, and each of the electrodes of the terminal electrode pair includes a second electrode pair. Any electrode is held lower than the held voltage, each of the electrodes of the first electrode pair is held at a lower voltage compared to the electrodes of the second electrode pair, and Up It is possible to grasp the invention as an ion implantation system that is maintained at a voltage lower than the voltage which the outer electrode is held in each of the inner electrodes of the electrode pairs each of the second electrode pair and the terminal electrode pair.
The electrostatic deflector includes a first electrode pair, a second electrode pair, and a terminal electrode pair. However, the electrostatic deflector is not intended to exclude those including other electrode pairs. In addition, other elements such as a lens may be interposed. In particular, the functional element may be exhibited by a gap between each electrode pair.

  It should be understood by those having ordinary skill in the art that various variations are possible without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 200 ... Deceleration / acceleration system, 202 ... Slot, 204 ... Correction apparatus, 206 ... Deceleration / acceleration element, 206a ... Electrode part, 206b ... Electrode part, 208 ... Focusing element, 208a ... Electrode part, 208b ... Electrode part, 210 ... Gap, 212 ... Electrostatic deflector, 213 ... Gap, 214 ... First electrode pair, 214a ... Outer electrode, 214b ... Inner electrode, 215 ... Gap, 216 ... Second electrode pair, 216a ... Outer electrode, 216b ... Inner electrode 218 ... Terminal electrode pair, 218a ... Outer electrode, 218b ... Inner electrode, 219 ... Inner electrode part, 220 ... Correction device, 221 ... Voltage source, 222 ... Focusing element, 223 ... Voltage source, 224 ... Duct, 224a ... Electrode Part, 224b ... electrode part, 225 ... voltage source, 226 ... end station, 227 ... controller, 228 ... wafer, 300 ... ion injection System 302 ... Aperture 304 ... Correction device 306 ... Deceleration / acceleration system 308 ... Electrostatic deflector 308a ... Outer electrode 308b ... Inner electrode 310 ... Split lens 312 ... Electrode pair 312a ... Downstream end face 314 ... Electrode pair, 314a ... Upstream end face, 316 ... Gap, 317 ... Correction device, 318 ... Focusing element, 320 ... Duct electrode, 400 ... Ion implantation system, 402 ... Slit, 404 ... Correction device, 406 ... Deceleration / Acceleration system, 408 ... electrostatic deflector, 410 ... split lens, 412 ... correction device, 414 ... focusing electrode, 416 ... electrode, 1100 ... ion implantation system, 1200 ... electrode pair, 1201 ... electrode pair, 1202 ... inner electrode, 1203 ... Outer electrode, 1204 ... Terminal electrode pair, 1300 ... Electrostatic deflector, 1300a ... Inner electrode, 1 00b ... outer electrode, 1302 ... electrode pairs, 1304 ... electrode pairs.

Claims (11)

An ion implantation system having a deceleration ratio of at least 2 and receiving an ion beam to decelerate the ion beam, and an electrostatic deflector arranged downstream of the deceleration system to deflect the ion beam Prepared,
The electrostatic deflector is
A first electrode pair disposed downstream of the deceleration system to receive the decelerated beam, the first electrode pair being spaced apart from each other to form an ion beam path therebetween And
A second electrode pair disposed downstream of the first electrode pair, the second electrode pair having an inner electrode and an outer electrode disposed apart from each other so as to form an ion beam path therebetween. And
A terminal electrode pair disposed downstream of the second electrode pair, the inner electrode and the outer electrode being spaced apart from each other so as to form an ion beam path therebetween,
The inner electrode of each of the first electrode pair, the second electrode pair and the terminal electrode pair is held at a voltage lower than the voltage at which the outer electrode of each of the electrode pairs is held;
Further, each of the electrode pairs can be independently applied with a voltage ,
Each of the electrodes of the terminal electrode pair is held lower than the voltage at which any electrode of the second electrode pair is held, and each of the electrodes of the first electrode pair is compared with the electrode of the second electrode pair An ion implantation system characterized in that it is held at a lower voltage .   2. The ion implantation system according to claim 1, wherein each of the electrodes of the terminal electrode pair and each of the electrodes of the first electrode pair are maintained at a negative voltage.   2. The ion implantation system according to claim 1, wherein one of the second electrode pairs is grounded and the other is held at a positive voltage.   Each of the electrodes of the terminal electrode pair and each of the electrodes of the first electrode pair are held at a negative voltage, and one of the second electrode pairs is grounded and the other is held at a positive voltage. The ion implantation system according to claim 1. The ion implantation system according to any one of claims 1 to 4, wherein the reduction ratio is in the range of about 5 to about 100. The decelerating system, in order to provide a reduction elements separated from the downstream of the focusing of the elements, claims 1 to 5, characterized in that the gap between the focusing of the elements and the deceleration element is formed The ion implantation system according to any one of the above . The ion implantation system according to any one of claims 1 to 6, further comprising an ion source for generating an ion beam. 2. An analysis magnet disposed downstream of the ion source and upstream of the deceleration system and receiving an ion beam produced by the ion source and generating a mass-selected ion beam. The ion implantation system according to claim 7 . A split lens comprising a first electrode pair disposed downstream of the electrostatic deflector and having a curved downstream end face and a second electrode pair having a curved upstream end face. The ion implantation system according to any one of claims 1 to 8, wherein the end surfaces of the first and second end surfaces are separated from each other to form a gap therebetween. An ion implantation system comprising an electrostatic deflector for deflecting an ion beam,
A first electrode pair having an inner electrode and an outer electrode spaced apart from each other so as to form an ion beam path therebetween,
A second electrode pair having an inner electrode and an outer electrode disposed downstream of the first electrode pair and spaced apart from each other so as to form an ion beam path therebetween,
A terminal electrode pair having an inner electrode and an outer electrode disposed downstream of the second electrode pair and spaced apart from each other so as to form an ion beam path therebetween,
Further, each of the electrodes of the terminal electrode pair is held lower than the voltage at which any electrode of the second electrode pair is held, and each of the electrodes of the first electrode pair is compared with the electrode of the second electrode pair. Is held at a lower voltage,
The inner electrode of each of the first electrode pair, the second electrode pair, and the terminal electrode pair is held at a voltage lower than the voltage at which the outer electrode of each of the electrode pairs is held. Ion implantation system. The first electrode pair and the outer electrode of the terminal electrode pair are held at a _first voltage (V ₁ ), and the inner electrode of the first electrode pair and the terminal electrode pair is a second voltage (V ₂ ). The ion implantation system of claim 10 , wherein

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