TWI618110B - Ion beam line - Google Patents

Abstract

In one aspect, an ion implantation system is disclosed, which includes a deceleration system configured to receive an ion beam and decelerate the ion beam with a reduction ratio of at least 2; and an electrostatic elbow, which is configured at The downstream side of the deceleration system to facilitate the deflection of the ion beam. The electrostatic elbow includes three series electrode pairs for receiving the decelerated ion beam, wherein each electrode pair has an inner electrode and an outer electrode separated from each other to allow the ion beam to pass therebetween. Each electrode of the last electrode pair is maintained at a potential that is less than the potential held by any electrode of the intermediate electrode pair, and the electrode of the first electrode pair is maintained at a lower potential relative to the electrode of the second intermediate electrode pair.

Description

Ion implantation system

This teaching relates generally to an ion implantation system and method, which includes a system and method for adjusting the current density of a strip-shaped ion beam to improve its cross-section uniformity.

Ion implantation technology has been used to implant ions into semiconductors to make integrated circuits for more than 30 years. Traditionally, such ion implantation uses three types of ion implanters: medium current, high current, and high energy implanters. The ion source included in the high-current implanter usually includes a lead-out hole in the form of a slit with high aspect ratios in order to improve the effect of space charge. The one-dimensional ion beam extracted from such an ion source can be focused into an elliptical cross-section to produce a substantially circular ion beam cross-section on a wafer on which the ion beam is incident.

Some recent commercial high-current ion implanters impinge a so-called ribbon ion beam onto a wafer to implant ions into it, which nominally assumes a one-dimensional profile. Using such a ribbon ion beam provides several advantages for wafer processing. For example, the strip-shaped ion beam may have a long dimension exceeding the diameter of the wafer and thus may remain stationary, scanning the wafer only in one dimension orthogonal to the direction of propagation of the ion beam and scanning the entire wafer Implanted ion. Furthermore, the ribbon ion beam can tolerate higher currents on the wafer.

However, the use of ribbon ion beams for ion implantation poses many challenges. war. For example, the longitudinal profile of the ion beam requires high uniformity to obtain an acceptable dose uniformity of the implanted ions. As wafer size increases (eg, the next generation of 450-mm wafers replaces the current 300-mm wafers), achieving acceptable longitudinal uniformity of the ribbon ion beam used to process the wafers will be more challenging.

In some conventional ion implantation systems, corrector optics are incorporated into the ion beamline to change the charge density of the ion beam during ion beam delivery. However, this method is usually used if the ion beam profile exhibits high non-uniformity immediately after extraction from the ion source, or due to space charge loading or beam transport optics Insufficient ion beam uniformity.

Therefore, there is a need for an enhanced ion implantation system that addresses the aforementioned disadvantages. In particular, there is a need for improved systems and methods for ion implantation that include enhanced systems and methods to generate an ion beam having a desired energy and a desired ion beam profile along an ion beam line.

In one aspect, a system for changing the energy of a band-shaped ion beam is disclosed. The system includes a correction device configured to receive a band-shaped ion beam and adjust a current density along a longitudinal dimension of the ion beam. Section; at least one deceleration / acceleration element defining a deceleration / acceleration region for decelerating or accelerating the ion beam when the ion beam passes through the at least one deceleration / acceleration element; a focusing lens for reducing the ions The beam diverges along its lateral dimension; and an electrostatic bend is disposed downstream of the deceleration / acceleration region to facilitate the deflection of the ion beam.

In some specific examples, the correction device may include a plurality of spaced apart electrode pairs stacked along a longitudinal dimension of the ion beam, each pair of electrodes being separated to form a A gap for the ion beam to pass through, wherein the electrode pairs are configured to be individually biased by the application of an electrostatic voltage so as to locally deflect the ion beam along the longitudinal dimension. Various electrode types can be used. In some specific examples, the electrode pairs may include plate electrodes configured to be substantially parallel or perpendicular to a plane formed by a propagation direction of the ion beam and a lateral dimension thereof. The system may further include at least one voltage source for applying the electrostatic voltages to the electrode pairs of the calibration device.

A controller connected to the at least one voltage source can control the application of the electrostatic voltages to the electrode pairs. For example, the controller may be configured to instruct the voltage source to apply an electrostatic voltage to the electrode pairs to locally deflect at least a portion of the ion beam so as to increase a current density profile along a longitudinal dimension of the ion beam Of uniformity.

The controller may be configured to, for example, determine the pair according to a measured current density profile of the ion beam after the ion beam passes near an analyzer magnet or a plane of a substrate on which the ion beam is incident. The electrostatic voltages applied to the electrode pairs of the calibration device.

In some embodiments, the controller is configured to apply a time-varying voltage to an electrode pair of the calibration device. For example, the controller may be configured to change the voltage applied to the electrode pair of the correction device in time so as to cause the ion beam to oscillate along the longitudinal dimension. The oscillating motion of the ion beam may exhibit, for example, an amplitude equal to or less than about 20 mm in a range of about 10 mm to about 20 mm. For example, the frequency of the oscillation may be in a range of about 1 Hz to about 1 kHz.

The focusing lens may include at least one focusing element, for example, a pair of opposing electrodes spaced to form a gap for receiving the ion beam. Furthermore, the deceleration / acceleration element may include a pair of spacers to form a lateral space for receiving the ion beam. Gap electrode. The focusing element and the deceleration / acceleration element may be arranged opposite to each other to form a gap therebetween, and may be maintained at different potentials so that ions pass through the gap and cause the ions to decelerate or accelerate.

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

In some specific examples, the at least one deceleration / acceleration element is disposed on a downstream side of the correction device and the at least one focusing element is disposed on a downstream side of the deceleration / acceleration element.

The focusing element may be disposed with respect to the electrostatic elbow to form a gap therebetween, wherein the focusing element and the electrostatic elbow are maintained at different potentials to form a gap in the gap suitable for reducing the ion beam along the Electric field diverging laterally.

In some specific examples, the electrostatic elbow includes an inner electrode and an opposite outer electrode, which are maintained at different potentials so as to promote the deflection of the ion beam. The electrostatic elbow may further include an intermediate electrode disposed on a downstream side of the internal electrode and opposite to the external electrode, wherein the internal electrode and the intermediate electrode are configured to be applied with independent potentials. In some cases, the external electrode and the intermediate electrode may be maintained at the same potential.

In some specific examples, the outer electrode of the electrostatic elbow includes an upstream portion and a downstream portion, which are arranged at an angle with respect to each other so that the downstream portion can be captured in the ion beam. Sex particles at least a part. The upstream and downstream portions may integrally constitute the external electrode, or they may be electrically coupled to each other. Individual sections.

In some specific examples, the system may further include another correction device disposed on the downstream side of the electrostatic elbow. The another correction device is configured to adjust a current density profile of the ion beam along the longitudinal dimension. . In some combinations, the downstream correction device may include a plurality of spaced electrode pairs stacked along the longitudinal dimension of the ion beam, each pair of electrodes being spaced apart to form a gap for the ion beam to pass through, wherein The electrode pairs are configured to be individually biased by the application of an electrostatic voltage so as to locally deflect the ion beam along the longitudinal dimension.

In some specific examples, the electrode pairs of the correction devices are staggered from each other along the longitudinal dimension of the ion beam. For example, the electrode pairs of the downstream correction device (along the longitudinal dimension of the ion beam) may be vertically offset relative to the individual electrode pairs of the upstream correction device by a half of the longitudinal height of the electrodes of the correction devices (pixel size Half).

In some specific examples, the system may further include another focusing lens (herein, also referred to as a second focusing lens), which is disposed on the downstream side of the other correction device so as to reduce the ion beam along the lateral direction. Size divergence. Furthermore, in some cases, an electrical grounding element may be disposed on the downstream side of the other focusing lens. The electrical ground element includes, for example, a pair of electrical ground electrodes spaced apart to allow the ion beam to pass therebetween. The second focusing lens may include at least one focusing element configured to form a gap therebetween with respect to the ground element, wherein a potential difference between the focusing element and the ground element generates an electric field in the gap in order to reduce the ion beam edge Diverging with this lateral dimension.

In other aspects, a system for decelerating a band-shaped ion beam is disclosed, including at least one deceleration element defining a region for receiving the band-shaped ion beam. Domain and decelerate its ions; at least a pair of deflection electrodes spaced to receive and decelerate the decelerated ion beam therebetween; and a correction device configured to provide a means for the deflected ion beam to pass through Channel and adjust the current density profile of the ion beam in a non-dispersive plane.

In some specific examples, the correction device may include a plurality of spaced apart electrode pairs stacked along a longitudinal dimension of the ion beam, each pair of electrodes being separated to form a gap for the ion beam to pass through, wherein the electrodes The pair is configured to be individually biased by the application of an electrostatic voltage so as to locally deflect the ion beam along the longitudinal dimension. In some specific examples, the plurality of separated electrode pairs may include internal and external opposing electrodes and an intermediate electrode disposed downstream of the internal electrode and opposite to the external electrode, wherein the external electrode, the internal electrode, and the intermediate electrode The system is configured to be maintained at an independent potential. For example, the internal electrode and the external electrode may be maintained at different potentials to promote the deflection of the ion beam, but the external electrode and the intermediate electrode may be maintained at the same potential. The external electrode may include an upstream portion and a downstream portion, wherein the downstream portion is disposed at an angle with respect to the upstream portion so as to capture neutral particles existing in the ion beam. In some embodiments, the upstream portion and the downstream portion of the external electrode integrally constitute the external electrode.

The system may further include at least one voltage source for applying the electrostatic voltages to the electrode pairs of the calibration device. A controller connected to the at least one voltage source may be provided to adjust the voltage applied to the electrode pair of the correction device. For example, the controller may determine a voltage to be applied to an electrode pair of the calibration device according to, for example, a measured current density profile of the received ion beam.

The system may further include a focusing lens configured to reduce divergence of the ion beam along its lateral dimension. The focusing lens may include at least one focus An element, for example, a pair of electrodes that are separated to allow an ion beam to pass therebetween. In some embodiments, an electrical grounding element, such as a pair of spaced electrodes, is disposed downstream of the focusing element. The electrical grounding element may be disposed relative to the focusing element to form a gap therebetween. The grounding element and the focusing element can be maintained at different potentials so as to form an electric field in the gap suitable for reducing the ion beam diverging along the lateral dimension.

In another aspect, an ion implantation system is disclosed that includes an ion source adapted to generate a band-shaped ion beam; an analysis magnet to receive the band-shaped ion beam and generate a mass selection (mass) -selected) a strip-shaped ion beam; and a correction system configured to receive the mass-selected strip-shaped ion beam and adjust a current density profile of the ion beam along its longitudinal dimension to generate a An output ribbon ion beam with a substantially uniform current density profile.

In some specific examples, the correction system may be further configured to decelerate or accelerate the ions of the reception mass selective ion beam so as to generate a deceleration / acceleration output band-shaped ion having a substantially uniform current density profile along the longitudinal dimension bundle. In some specific examples, the output band-shaped ion beam presents a current density profile with a root mean square (RMS) deviation or non-uniformity equal to or less than about 5% along the longitudinal dimension. For example, the output band-shaped ion beam may exhibit an RMS deviation or unevenness along the longitudinal dimension that is equal to or less than about 4% or equal to or less than about 3% or equal to or less than about 2% or equal to or less than about 1%. Current density profile.

In some specific examples, the calibration system in the above-mentioned ion implantation system may further include a focusing lens for reducing the divergence of the strip-shaped ion beam along its lateral dimension. Furthermore, in some specific examples, the correction system may be configured to remove neutral particles (eg, neutral atoms and / or molecules) present in the mass-selective ion beam. At least part of it. For example, the correction system includes an electrostatic elbow for the neutral particles to continue to propagate in their direction of propagation to be stopped by an ion beam trap (for example, an electrode outside the electrostatic elbow). Part of the ion beam) to change the propagation direction of the ions in the ion beam.

The ion implantation system may further include an end-station for holding a substrate (eg, a wafer), wherein the output band-shaped ion beam propagates to the terminal station to be incident on the substrate. In some specific examples, the correction system may be configured to adjust the propagation direction of the ion beam so that the output band-shaped ion beam is along a direction at a desired angle (for example, a 90 degree angle) with the surface of the substrate. Incident on the surface of the substrate.

In some specific examples, the calibration system of the ion implantation system can promote the oscillating movement of the ion beam, so as to improve the uniformity of the dose of the implanted ions of the output band-shaped ion beam in the substrate.

In some specific examples, the calibration system of the ion implantation system may include at least one calibration device for adjusting a current density profile of the ion beam along the longitudinal dimension. Such a correction device may include, for example, a plurality of spaced apart electrode pairs stacked along the longitudinal dimension of the ion beam, each pair of electrodes separated to form a gap for the ion beam to pass through, wherein the electrode pairs are configured to Individually biasable by the application of an electrostatic voltage to locally bias the ion beam in the non-dispersed plane. The ion implantation system may also include at least one voltage source for applying voltage to the electrode pairs of the calibration device; and a controller connected to the at least one voltage source to adjust the voltage applied to the electrode pairs. Voltage.

In some aspects, a method for changing the energy of a band-shaped ion beam is disclosed, which includes passing a band-shaped ion beam through a region in which an electric field exists so that Decelerate or accelerate the ions of the ion beam, adjust the current density profile of the strip-shaped ion beam along its longitudinal dimension, and reduce the divergence of the strip-shaped ion beam along its lateral dimension. The step of reducing the divergence of the ion beam includes passing the ion beam through a focusing lens.

In some specific examples, the band-shaped ion beam may have an initial energy between about 10 keV and about 100 keV. In some embodiments, the step of decelerating or accelerating the ions of the ion beam changes the energy of the ion beam by a factor ranging from about 1 to about 30.

The step of adjusting the current density profile of the ion beam along its longitudinal dimension may include using a correction device adapted to locally deflect the ion beam along the longitudinal dimension so as to generate a substantially uniform current along the longitudinal dimension. Density profile.

In some aspects, a method for implanting ions in a substrate is disclosed, which includes extracting a band-shaped ion beam from an ion source; passing the band-shaped ion beam through an analysis magnet to generate a mass-selective band-shaped ion beam Adjusting the current density profile of the mass selection band ion beam along at least one longitudinal dimension thereof to generate an output band ion beam having a substantially uniform current density profile along the longitudinal dimension; and guiding the output band ion Beam onto a substrate to implant ions into the substrate.

In some specific examples, a correction device may be configured to perform the step of adjusting the current density profile of the mass-selective band-shaped ion beam. For example, a calibration device can adjust the current density profile of the mass-selective band-shaped ion beam in order to obtain an ion beam that exhibits a substantially uniform current density profile.

In some specific examples, the ion implantation method may further include decelerating or accelerating the ions of the mass selection band ion beam, so that the output band ion beam has an energy different from the energy of the mass selection band ion beam. .

In some specific examples, the implanted ion dose may be between about 10 ¹² cm ^-2 and about 10 ¹⁶ cm ^-2 . The ionic current can be, for example, tens of microamperes (e.g., 20 microamps) to tens of milliamps (e.g., 60 milliamps), for example, between about 50 microamps to about 50 milliamps, or, for example, about 2 milliamps to about 50 milliamps.

In many ion implantation applications, even when an accelerating / decelerating system is operating and the received ions are decelerated at a moderate deceleration ratio, one is composed of two separate electrodes and is arranged downstream of the accelerating / decelerating system. An electrostatic elbow (eg, the above-mentioned electrostatic elbow) can effectively bend an ion beam without causing significant angular divergence of the ion beam ("blow-up"). However, it has been found that the use of a conventional electrostatic elbow on one of the downstream sides of a deceleration system configured to decelerate ions with a high deceleration ratio may cause over-focusing of the plasma, where the ion As the beam travels through downstream components, the ion beam spreads in turn. The divergence of the ion beam causes ion loss and interferes with the operation of the ion implantation system. In addition, in some conventional ion implantation systems, the use of focusing lenses that require high voltage may cause transient ion beam instability, for example, due to arcing and contaminants generated in neutral atom / molecular form via charge exchange reactions. Stability. Some aspects of the technology discussed below address these issues.

In one aspect, an ion implantation system is disclosed, which includes a deceleration system configured to receive an ion beam and decelerate the ion beam at a reduction ratio of at least 2; and an electrostatic elbow configured at The downstream side of the deceleration system to facilitate the deflection of the ion beam. The electrostatic elbow includes a first electrode pair, which is disposed on the downstream side of the deceleration system to receive the decelerated ion beam. The first electrode pair has a separate internal electrode and an external electrode to allow the ion beam to Passed in between; a second electrode pair, which is arranged on the downstream side of the first electrode pair and has a separate internal electrode and an external An electrode to allow the ion beam to pass therebetween; and a final electrode pair disposed on the downstream side of the second electrode pair and having an internal electrode and an external electrode separated to allow the ion beam to pass therebetween. The first, second and last electrode pairs are configured to be independently biased. In some specific examples, each electrode of the last electrode pair is maintained at a potential that is less than a potential held by any electrode of the second electrode pair. The electrodes of the first electrode pair are also kept at a lower potential than the electrodes of the second electrode pair.

In some specific examples, the reduction system is configured to provide a range of about 5 to about 100 (for example, a range of about 10 to about 80, or a range of about 20 to about 60, or a range of about 30 to about (About 50 range).

In some specific examples, the internal electrodes of each of these electrode pairs are maintained at a potential that is less than the potential held by the individual external electrodes of that electrode pair, so as to promote the deflection of an ion beam composed of positively charged particles .

The inner and outer electrodes of the first electrode pair may form a certain angle with respect to an individual electrode of the second electrode pair. Furthermore, each of the inner and outer electrodes of the last electrode pair may form a certain angle with respect to an individual electrode of the second electrode pair.

In some specific examples, the outer electrodes of the first and last electrode pairs are maintained at a first potential V ₁ and the inner electrodes of the first and last electrode pairs are maintained at a second potential V ₂ . Furthermore, the inner electrode of the second electrode pair is electrically grounded and the outer electrode of the second electrode pair is maintained at a third potential V ₃ . The voltage V ₁ may be greater than the voltage V ₂ . For example, V ₁ may be in the range of from about 0V to about -30 kV, V ₂ can range from about 0V (zero volts) to about -30 kV (negative 30kV) of, and V ₃ may be from about 0V to about + Within 30kV.

In some embodiments, the ion beam is a band-shaped ion beam, while in other embodiments, the ion beam is a circular ion beam.

In some specific examples, the ion beam received by the deceleration system has an ion energy in a range of about 10 keV to about 60 keV (eg, in a range of about 10 keV to about 20 keV) and a range of about 0.1 mA to about 40 mA Within (for example, in the range of about 5 mA to about 40 mA).

In some specific examples, the reduction system includes a reduction element that is separated from a downstream focusing element so as to define a gap therebetween. The deceleration system may include two relatively separated equipotential electrode portions with a passage therebetween for the ion beam to pass through. The focusing element may also include two equipotential separation electrode portions with a passage provided therebetween for the ion beam to pass through. In some specific examples, separate electrode portions of each of the speed reduction element and the focusing element may be connected at their top and bottom ends to form, for example, a square electrode. The electrodes of the deceleration element and the focusing element are maintained at different potentials to provide an electric field in the gap so as to decelerate the received ion beam. When the ion beam passes through the gap, the electric field can also promote the focusing of the ion beam.

The ion implantation system may further include an ion source for generating the ion beam; and an analysis magnet configured on a downstream side of the ion source and on an upstream side of the deceleration system to receive the ion source The ion beam is generated and a mass selective ion beam is generated.

In a related aspect, an ion implantation system is disclosed, which includes an electrostatic elbow for promoting the deflection of an ion beam, wherein the electrostatic elbow includes a first electrode pair having a separate internal electrode and An external electrode to allow the ion beam to pass therebetween; a second electrode pair disposed on the downstream side of the first electrode pair and having a separate internal electrode and an external electrode to allow the ion beam to pass therebetween And a final electrode pair, which is disposed on the downstream side of the second electrode pair and has a separate internal electrode and an external electrode to allow the ion beam to pass therebetween. Make each of the last electrode pair The electrode is maintained at a potential that is less than the potential held by any of the electrodes of the second electrode pair, and the electrode of the first electrode pair is maintained at a lower potential relative to the electrode of the second electrode pair. Furthermore, the internal electrode of each of these electrode pairs is maintained at a potential that is less than the potential held by the individual external electricity of that electrode pair.

In some specific examples of the above-mentioned ion implantation system, the outer electrodes of the first and last electrode pairs are maintained at a first potential (V ₁ ) and the inner electrodes of the first and last electrode pairs are maintained at a first potential (V ₁ ). The second potential (V ₂ ). Furthermore, the inner electrode of the second electrode pair is electrically grounded and the outer electrode of the second electrode pair is maintained at a third potential (V ₃ ). The voltage V ₁ can be corrected more than the voltage V ₂ . For example, V ₁ may be in the range of (negative 30kV) of, V ₂ may be in the range of from about 0V to about -30kV, and V ₃ may be within the range from about 0V to about -30kV about 0V to about + 30kV of .

In some specific examples, the ion implantation system may further include a split lens disposed on a downstream side of the electrostatic elbow. The tangent lens may include a first electrode pair having a curved downstream end surface and a second electrode pair having a curved upstream end surface, wherein the end surfaces of the two electrode pairs are separated from each other to form a gap therebetween. The first and second electrode pairs are configured to be independently biased. For example, the first and second electrode pairs are biased so as to generate an electric field in the gap to focus the ion beam passing through the pair of tangent lenses.

In another aspect, an ion implantation system is disclosed, which includes an electrostatic elbow for receiving an ion beam and promoting its deflection; and a pair of tangent lenses disposed downstream of the electrostatic elbow. The tangent lens includes a first electrode pair having a curved downstream end surface and a second electrode pair having a curved upstream end surface, wherein the end surfaces of the two electrode pairs are separated from each other to form a gap therebetween. The first and second electrode pairs are configured to be independently biased, for example, to generate an electric field in the gap to focus the ion beam passing through the pair of tangent lenses. The ion implantation system may further include an acceleration / deceleration system disposed on the upstream side of the electrostatic elbow; and a mass analyzer disposed on the upstream side of the acceleration / deceleration system for receiving an ion beam and generating A mass selective ion beam. In some specific examples, the electrostatic elbow may include a first electrode pair, a second electrode pair, and a last electrode pair, each of which has a separate internal electrode and an external electrode to allow the ion beam Passed in between. The three electrode pairs are configured to be independently biased. For example, each electrode of the last electrode pair can be maintained at a potential lower than the potential held by any of the electrodes of the second electrode pair, and the electrode of the first electrode pair can also be opposite to the second electrode pair. The electrodes remain at a low potential. In some specific examples, the outer electrodes of the first and last electrode pairs are maintained at a first potential (V ₁ ) and the inner electrodes of the first and last electrode pairs are maintained at a second potential (V ₂ ). In some specific examples, V _{1 is} more corrected than V ₂ . Furthermore, the inner electrode of the second electrode pair can be electrically grounded, and the outer electrode of the second electrode pair can be maintained at a third potential (V ₃ ).

Furthermore, by referring to the detailed description and related drawings below, various aspects of the teaching can be understood. The schemes are briefly described below.

10‧‧‧ ion implantation system

12‧‧‧ ion source

14‧‧‧ lead-out electrode

16‧‧‧Suppression electrode

18‧‧‧ focusing electrode

19‧‧‧ ground electrode

20‧‧‧ Analysis Magnet

20a‧‧‧Variable size mass analysis hole

22‧‧‧correction system (deceleration / acceleration system)

24‧‧‧Terminal

25‧‧‧ substrate holder

26‧‧‧ substrate

28‧‧‧ electron gun

28a‧‧‧cathode

28b‧‧‧Anode

30‧‧‧ electron gun

30a‧‧‧ cathode

30b‧‧‧Anode

32‧‧‧Ionization chamber

34‧‧‧ Plasma electrode

36‧‧‧ lead-out electrode

38‧‧‧ Solenoid Coil Assembly

40‧‧‧ slit

40a‧‧‧Gas feeder

40b‧‧‧Gas feeder

40c‧‧‧Gas feeder

40d‧‧‧Gas feeder

40e‧‧‧Gas feeder

42‧‧‧calibration device

44‧‧‧controller

46‧‧‧Deceleration / acceleration element

46a‧‧‧deceleration / acceleration electrode

46b‧‧‧deceleration / acceleration electrode

48‧‧‧ focusing element

48a‧‧‧focusing electrode

48b‧‧‧focusing electrode

50‧‧‧Gap area

52‧‧‧Static elbow

52a‧‧‧External electrode

52b‧‧‧Internal electrode

52c‧‧‧Intermediate electrode

53‧‧‧ Clearance

54‧‧‧correction device

56‧‧‧ focusing element

56a‧‧‧electrode

56b‧‧‧electrode

58‧‧‧ Clearance

60‧‧‧ grounding element

60a‧‧‧Electric ground electrode

60b‧‧‧Electric ground electrode

62‧‧‧ Clearance

100‧‧‧ waveform generator

102‧‧‧Profiler

200‧‧‧ deceleration / acceleration system

202‧‧‧Slit

204‧‧‧ Calibration device

206‧‧‧Deceleration / acceleration element

206a‧‧‧electrode section

206b‧‧‧electrode section

208‧‧‧ Downstream Focusing Element

208a‧‧‧electrode section

208b‧‧‧electrode section

210‧‧‧ Clearance

212‧‧‧electrostatic elbow

213‧‧‧Gap

214‧‧‧electrode pair

214a‧‧‧External electrode

214b‧‧‧Internal electrode

215‧‧‧Gap

216‧‧‧electrode pair

216a‧‧‧External electrode

216b‧‧‧Internal electrode

218‧‧‧electrode pair

218a‧‧‧External electrode

218b‧‧‧Internal electrode

219‧‧‧ Internal electrode section

220‧‧‧ Calibration device

221‧‧‧Voltage source

222‧‧‧Focus Element

223‧‧‧Voltage source

224a‧‧‧Ground electrode section

224b‧‧‧Ground electrode section

225‧‧‧Voltage source

226‧‧‧Terminal

227‧‧‧Controller

228‧‧‧wafer

300‧‧‧ Implantation System

302‧‧‧hole

304‧‧‧correction device

306‧‧‧ Deceleration / Acceleration System

308‧‧‧electrostatic elbow

308a‧‧‧curved external electrode

308b‧‧‧ curved inner electrode

310‧‧‧ Conical lens

312‧‧‧electrode pair

312a‧‧‧ Curved downstream end face

314‧‧‧electrode pair

314a‧‧‧curved upstream end face

316‧‧‧ bending gap

317‧‧‧correction device

318‧‧‧ focusing element

320‧‧‧ ground electrode

400‧‧‧ ion implantation system

402‧‧‧Slit

404‧‧‧correction device

406‧‧‧Deceleration / Acceleration System

408‧‧‧E-bend

410‧‧‧Convex lens

412‧‧‧correction device

414‧‧‧Focus electrode

416‧‧‧ ground electrode

1100‧‧‧ ion implantation system

1200‧‧‧ electrode pair

1201‧‧‧electrode pair

1202‧‧‧Internal electrode

1203‧‧‧External electrode

1204‧‧‧electrode pair

1205‧‧‧electrode pair

1206‧‧‧electrode pair

1300‧‧‧Traditional E-bend

1300a‧‧‧Internal electrode

1300b‧‧‧External electrode

1302‧‧‧electrode pair

1304‧‧‧electrode pair

1306‧‧‧electrode pair

DP‧‧‧ Downstream

E1‧‧‧electrode pair

E1a‧‧‧electrode

E1b‧‧‧electrode

E2‧‧‧electrode pair

E2a‧‧‧electrode

E2b‧‧‧electrode

E3‧‧‧electrode pair

E4‧‧‧electrode pair

E4a‧‧‧electrode

E4b‧‧‧electrode

E5‧‧‧electrode pair

E6‧‧‧electrode pair

E7‧‧‧electrode pair

E8‧‧‧electrode pair

E9‧‧‧electrode pair

E10‧‧‧electrode pair

H‧‧‧length

R1‧‧‧curvature radius

UF‧‧‧ upstream

UP‧‧‧ Upstream

V1‧‧‧ voltage source

V2‧‧‧ voltage source

V3‧‧‧ voltage source

V4‧‧‧ voltage source

V5‧‧‧ voltage source

V6‧‧‧ voltage source

V7‧‧‧ voltage source

V8‧‧‧ voltage source

V9‧‧‧ voltage source

V10‧‧‧ voltage source

V11‧‧‧Voltage source

V12‧‧‧voltage source

V13‧‧‧Voltage source

V14‧‧‧Voltage source

V15‧‧‧Voltage source

V16‧‧‧Voltage source

V17‧‧‧Voltage source

V18‧‧‧Voltage source

V19‧‧‧Voltage source

V20‧‧‧ voltage source

W‧‧‧Horizontal size

FIG. 1 outlines a band-shaped ion beam; FIG. 2A outlines an ion implantation system according to a specific example of the present teaching; FIG. 2B outlines an ion implantation system used in FIG. 2A A calibration system according to a specific example of the present teaching; FIG. 2C is a schematic side sectional view of a portion of the calibration system shown in FIG. 2B; FIG. 3A is a partial schematic diagram of an ion source for generating a band-shaped ion beam; FIG. 3B is another partial schematic diagram of the ion source of FIG. 3A; FIG. 3C is another partial schematic diagram of the ion source of FIGS. 3A and 3B; A current profile of an exemplary band-shaped ion beam generated by an ion source is depicted according to the ion source shown in FIGS. 3A-3B below; FIG. 5 outlines a calibration system suitable for use in a specific example of the present teachings Figure 6 outlines a band-shaped ion beam that passes through a correction device according to a specific example of the present teaching; Figure 7A outlines a band-shaped ion beam that passes through a correction device according to a specific example of the present teaching; The correction device is configured to apply a lateral electric field to at least a portion of the ion beam; FIG. 7B outlines a band-shaped ion beam that passes through a correction device according to a specific example of the present teaching. The correction device is configured It is used to apply a longitudinal electric field to the ion beam so as to promote its deflection; FIG. 7C schematically depicts the ramp voltage of an electrode pair used to apply the correction device shown in FIG. 7B; FIG. 8A outlines a pass voltage A specific example of the present teaching is a band-shaped ion beam of a correction device configured to cause a longitudinal oscillating movement of the ion beam; FIG. 8B schematically depicts a correction for applying to the correction shown in FIG. 8A The triangular voltage of the electrode pair of the device; FIG. 9 is a partial schematic diagram of the ion implantation system shown in FIGS. 2A, 2B, and 2C, which further depicts an ion beam profiler for measuring the current profile of the ion beam; FIG. Correct the simulated current profile of the ribbon ion beam as a function of height; FIG. 10B shows that an exemplary voltage may be applied to an electrode pair in one of the calibration devices of the ion implantation system shown in FIGS. 2A, 2B, and 2C to provide a rough correction of the ion beam profile shown in FIG. A simulated cross-section of a partially corrected ion beam obtained from a coarse correction; FIG. 10C shows that an exemplary voltage can be applied to an electrode pair of another correction device of the ion implantation system shown in FIGS. 2A, 2B, and 2C to improve FIG. 10B. The uniformity of the partially corrected ion beam and the simulated cross-section of the corrected ion beam obtained in this way are shown; FIG. 11A outlines an ion implantation system according to a specific example in which a three-electrode pair is used. Electrostatic elbow; FIG. 11B is a schematic partial view of the ion implantation system shown in FIG. 11A in a dispersed plane

FIG. 11C is a different schematic partial view of the ion implantation system shown in FIG. 11A in a non-dispersed plane; FIG. 11D schematically depicts a voltage source for applying a voltage to an electrode of the electrostatic elbow and a voltage source for controlling the Controller of the voltage source; Figure 12A shows the theoretical simulation results of an ion beam passing through a reduction system operating at a reduction ratio of 60 and a downstream electrostatic elbow consisting of two spaced electrodes; Figure 12B shows an ion beam passing A theoretical simulation result of a deceleration system operating at a reduction ratio of 60 and a downstream electrostatic elbow composed of 3 electrode pairs; FIG. 13A shows an As ion beam having an energy of 30 keV and a current of 25 mA passing through a two-space The theoretical simulation results of an electrostatic elbow formed by electrodes; FIG. 13B shows the theoretical simulation results of an As ion beam with an energy of 30keV and a current of 25mA passing through an electrostatic elbow (E-bend) composed of three series electrode pairs; Fig. 14A is a perspective view of a lens having a tangential lens disposed downstream of an electrostatic elbow. A partial schematic cross-sectional view of the ion implantation system in a dispersed plane; FIG. 14B is a partial schematic side view in a non-dispersive plane of the ion implantation system shown in FIG. 14A; and FIG. Partial schematic diagram of the dissected plane of the formed electrostatic elbow and an ion implantation system of a tangential lens disposed downstream of the electrostatic elbow.

In some aspects, the present teachings relate to an ion implantation system (also referred to herein as an ion implanter), which includes an ion source for generating a band-shaped ion beam and a band for ensuring the band A correction system in which the shaped ion beam has a substantially uniform current density profile at least along a longitudinal dimension of the ion beam at a substrate on which the ion beam is incident. In some cases, when the ion beam is delivered to a substrate for implanting ions into the substrate, the calibration system and other optical elements in the ion beam line of the ion implantation system can be used to substantially maintain a A cross-section (e.g., in the range of about 5% or better) of a band-shaped ion beam from an ion source.

In some specific examples, the ion implantation system according to the present teaching includes an ion beam line having two phases (an ion beam implantation phase, followed by an ion beam correction phase), which may also optionally include an A mechanism to decelerate or accelerate the ion beam. The implantation phase may include ion beam generation and mass selection. In some specific examples, the ion beam correction phase may include a corrector array and a deceleration / acceleration optical element. In some embodiments, the ion beam line may be configured to implant ions into a 300-mm substrate (for example, via a strip-shaped ion beam having a height of approximately 350-mm) or a 450-mm substrate (for example, via an Strip-shaped ion beam at approximately 500-mm height). For example, the ion beam line may include a replaceable ion optics configuration kit suitable for different substrate sizes. The ion The optical configuration kit may include, for example, an extraction electrode for extracting an ion beam from an ion source, a deceleration / acceleration phase optical element, and a substrate processing assembly in a terminal station of the ion implanter, for example, a replacement end effector. end effector) and FOUPs.

Various exemplary specific examples of the present teaching are described below. The terms used in these specific examples have their ordinary meaning in the art. For clarity, the following terms are defined.

The term "ribbon ion beam" as used herein means having its largest dimension (herein also referred to as the longitudinal dimension of the ion beam) and its smallest dimension (herein also referred to as the ion The beam has an aspect ratio of an ion beam having an aspect ratio of at least about 3, for example, equal to or greater than 10, or equal to or greater than 20, or equal to or greater than 30. A strip-shaped ion beam can take on a variety of different sectional views. For example, a ribbon ion beam may have a rectangular or oval cross-sectional view. FIG. 1 outlines an exemplary ribbon ion beam having a longitudinal dimension (here, also referred to as height) H and a lateral dimension (here, also referred to as width) W. Without loss of generality, in the following description of various specific examples of the present invention, it is assumed that the propagation direction of the ion beam is along the z-axis of the Cartesian coordinate system, the longitudinal dimension is along the y-axis, and the lateral dimension Along the x-axis. As discussed in more detail below, in these many specific examples, an analysis magnet is used to disperse the ion beam in a plane perpendicular to the propagation direction of the ion beam. This plane is referred to herein as the scattering plane. In the following specific example, the dispersion plane corresponds to the xz plane. A plane perpendicular to the dispersion plane is called a non-dispersion plane. In the following specific example, the non-dispersion plane corresponds to the yz plane.

As used herein, the term "current density" is consistent with that used in the art, which means that it flows through a unit area (e.g., perpendicular to the direction of propagation of ions). Current per unit area) associated with the plasma.

The term "current density profile" as used herein means that the current density of the ion beam is a function of the position along the ion beam. For example, an ion current density profile along the longitudinal dimension of the ion beam means that the ion current density is away from a reference point along the longitudinal dimension of the ion beam (for example, the upper or lower edge or center of the ion beam) A function of the distance or an ion-related current flowing through the unit length along the longitudinal dimension.

The term "substantially uniform current density profile" means an ion current density profile that exhibits a maximum 5% change in RMS.

The term "deceleration ratio" means the ratio of the energy of the ion beam entering a deceleration system to the energy of the ion beam leaving the deceleration system (i.e., the energy of the ion beam received by the deceleration system and the energy of the deceleration ion beam ratio).

Referring to FIGS. 2A, 2B, and 2C, an ion implantation system 10 according to a specific example of the present teaching includes an ion source 12 for generating a band-shaped ion beam and an electrical bias to assist the ion beam from the ion beam. A puller electrode 14 from which the ion source is drawn. A suppressing electrode 16 is biased with electric power to prevent neutralizing electrons (for example, the electrons generated by ionization of the ambient gas from flowing back to the ion source); a focusing electrode 18 is biased with electric power to reduce Divergence of the ion beam; and a ground electrode 19 defines a reference ground of the ion beam. An analysis magnet 20 disposed downstream of the focusing electrode 18 receives the band-shaped ion beam and generates a mass selective ion beam.

In some specific examples, the ion source housing and the analysis magnet frame assembly can be electrically isolated from the ground potential. For example, they can be floated below the ground potential at, for example, -30 kV. In some cases, the floating voltage can be selected so that the ion beam is extracted from the ion source and the ion beam is incident with the ion beam on top of the ion beam. The ion beam is subjected to mass analysis by a high energy at the substrate implanted therein. In another option, the ion beam can be extracted and mass analyzed, and then the ion beam can be accelerated to impinge on the substrate with higher energy.

Referring again to FIGS. 2A-2C, as discussed in more detail below, the exemplary ion implantation system 10 further includes a correction system 22 for adjusting a longitudinal dimension along at least the ion beam (e.g., in the ion beam In the non-dispersion plane) of the ion beam to produce an output band-shaped ion beam that exhibits a substantially uniform current density profile along at least its longitudinal dimension. Furthermore, the correction system 22 can adjust the lateral size of the ion beam, for example, reduce the ion beam to diverge along the lateral size (eg, in the dispersion plane) to ensure that the output ion beam has a desired lateral size.

In some specific examples, such as those discussed below, the correction system 22 may further provide deceleration / acceleration of the mass-selective band-shaped ion beam. In this way, an output band-shaped ion beam having a desired energy and a substantially uniform current density profile can be obtained. Without losing its generality, in the specific examples discussed below, the correction system 22 is also referred to as a deceleration / acceleration system. However, it should be understood that, in some specific examples, the correction system 22 may not provide deceleration or acceleration of the ion beam.

The exemplary ion implantation system 10 further includes an end station 24 including a substrate holder for holding a substrate 26 in a path away from the ribbon ion beam of the calibration system 22 ) 25. In this specific example, the substrate holder can be scanned in a manner known in the art along a dimension orthogonal to the propagation direction of the ion beam to expose different portions of the substrate to the ion beam in order to Ions are implanted into it. In some specific examples, the longitudinal dimension of the ion beam is larger than the diameter of the substrate, so that linear movement of the substrate along a dimension perpendicular to the propagation direction of the ion beam can cause implantation of ions throughout the entire substrate. The lose The approximate uniformity of the current density of the strip-shaped ion beam ensures that a uniform dose can be achieved by the implanted ions across the substrate.

As the ion source 12, various ion sources capable of generating a band-shaped ion beam can be used. It is described in U.S. Patent No. 6,664,547 with the invention name `` Ion Source Ribbon Beam with Controllable Density Profile '' and U.S. Patent No. 7,791,041 with the invention name `` Ion Source, Ion Implantation Apparatus, and Ion Implantation Method ''. Some examples of beam ion sources are incorporated herein by reference in their entirety.

The ion source 12 used in this specific example is described in U.S. Published Application No. 2014/0265856 with the invention name "Magnetic Field Source For An Ion Source" and the invention name "Ion Source Having At Least One Electron Gun Comprising A Gas" Inlet And A Plasma Region Defined by An Anode And A Ground Element Thereof "in US Patent No. 8,994,272, the entire contents of which are incorporated herein by reference. In brief, referring to FIGS. 3A, 3B and 3C, the ion source 12 may include two opposite external electron guns 28/30, which are arranged at both ends of a long and narrow rectangular ionization chamber 32 (the ion source body). Each electron gun may include an indirect heating cathode (IHCs) 28a / 30a and an anode 28b / 30b. As shown in FIG. 3C, a plate-shaped plasma electrode 34 includes a hole (for example, the hole may be a 450 mm × 6 mm slit) formed to allow ions to be drawn out of the ion source. An extraction electrode 36 similar to the shape of the plasma electrode and separated from the plasma electrode by one or more electrically insulating spacers (not shown) is used to assist ion extraction. In some specific examples, the lead-out electrode 36 can be biased up to -5 kV relative to the ion source body and the plasma electrode.

Referring to FIG. 3B, the ion source body is immersed in an axial magnetic field generated by the electromagnetic coil assembly 38. In this specific example, the coil assembly includes three secondary coils, which are distributed along the long axis of the ion source body and generate independent and partially overlapping magnetic fields throughout the top, middle, and bottom of the ion source body. The magnetic field limits the primary electron beam generated by the electron guns, thus creating a well-defined plasma column along the axis of the ionization chamber. The magnetic flux density generated by each of the three coil segments can be independently adjusted to ensure that the current density of the extracted ion beam is substantially free of unevenness.

Referring to FIG. 3C, five individual gas feeders 40a, 40b, 40c, 40d, and 40e distributed along the long axis of the ion source body can be used to adjust the ion density along the plasma column, each of which The gas feeder has its own dedicated mass flow controller (MFC). In this specific example, the anodes and cathodes of the electron guns, the plasma electrodes and the extraction electrodes are made of graphite. The ionization chamber is made of aluminum and its inner surface is coated with graphite.

The extracted ion beam can be analyzed by a retractable beam profiler located in the ion source housing. For clarity, FIG. 4 depicts the ion beam current as a function of the vertical (longitudinal) position of the band-shaped ion beam generated by such a prototype ion source. The current density profile along this longitudinal dimension exhibits an RMS non-uniformity of about 2.72%.

Referring to FIG. 2A again, in this specific example, the ion beam generated by the ion source 12 is extracted and accelerated to a desired energy (for example, between 5 and 80 keV) before entering the analysis magnet 20. The analysis magnet 20 applies an electric field to the ion beam in the non-dispersion plane to separate ions having different mass-to-charge ratios in the dispersion plane, thereby generating a focal plane of the analysis magnet with a waist in the dispersion plane. width (waist) mass selective ion beam. As described below, a variable size mass resolving aperture 20a arranged near the waist width of the ion beam allows ions having a desired mass-to-charge ratio to be transmitted downstream to the ones discussed in more detail below. Other components of the system.

Various analytical magnets known in the art can be used. In this specific example, the analysis magnet has a saddle-shaped coil design with a 600 mm magnetic pole gap, a bending angle of about 90 degrees, and a bending radius of 950 mm, but other magnetic pole gaps, bending angles, and bending radii may also be used. The configured variable-size mass-analysis hole 20 a allows ions having a desired mass-to-charge ratio to be transmitted downstream to the deceleration / acceleration system 22. In other words, the analysis magnet 20 generates a mass-selective band-shaped ion beam received by the deceleration / acceleration system 22.

With continued reference to FIGS. 2A, 2B, and 2C, the deceleration / acceleration system 22 includes a slit 40 for receiving the mass selective band ion beam. The slit 40 is high enough to accommodate the longitudinal dimension of the ion beam. In some specific examples, the slit 40 is 600 mm high and has a selectable range (for example, between about 5 mm to about 60 mm). ) Continuously changing lateral dimensions (e.g., dimensions in the dispersion plane).

A correction device 42 is disposed on the downstream side of the slit 40 so as to receive the band-shaped ion beam passing through the slit. In this specific example, as shown schematically in FIG. 5, the correction device 42 includes a plurality of spaced apart electrode pairs E1, E2, E3 stacked along the longitudinal dimension of the ion beam (that is, along the y-axis). , E4, E5, E6, E7, E8, E9 and E10, each of which can be individually biased with power. More specifically, in this specific example, a plurality of electrostatic voltage sources V1, V2, V3, V4, V5, V6, V7, V8, V9, and V10 apply independent voltages to each electrode pair in order to generate a voltage having voltages along the band. Electric field of the longitudinal dimension component of a shaped ion beam to locally make one of the ion beams Or more, the current density profile of the ion beam along the longitudinal dimension is adjusted. In this specific example, the adjustment of the current density profile is performed to improve the uniformity of the current density of the ion beam along its longitudinal dimension (for example, in the non-dispersion plane). The voltage sources V1, ..., V10 may be independent voltage sources or different modules of a single voltage source.

Each electrode pair includes two electrodes, for example, electrodes E1a and E1b, which are arranged substantially parallel to a plane defined by the propagation direction of the ion beam and its longitudinal dimension. The electrode pairs are separated from each other to provide a lateral gap through which the ion beam can pass. The electrode pair may be selected, for example, based on the longitudinal size of the ion beam, the resolution required to correct non-uniformities in the longitudinal profile of the ion beam, the type of ions in the ion beam Of the number. In some specific examples, the number of electrode pairs may be, for example, in a range of about 10 to about 30.

The controller 44 connected to the voltage sources V1,..., V10 may decide to apply a voltage (eg, a static voltage) to the electrode pair of the correction device in a manner described in more detail below to locally pass the electrodes. One or more of the ion beams between one or more electrode pairs in the pair are biased toward a selected angle, thereby adjusting the current density of the ion beam along its longitudinal dimension.

For example, FIG. 6 shows that the three electrodes are biased to E5, E6, and E7 by applying an electrostatic voltage, so that the voltage applied to E6 is greater than the voltage applied to E5 and E7, and in the shadow of the ion beam An electric field component indicated by an arrow is generated in a partially passing region, and a shaded portion of the ion beam exhibits a higher charge density than the other portions of the ion beam (in this example, the other electrode pairs are maintained at a ground potential). The electric field applied to the shaded part of the ion beam causes the upward bias of the upper segment of that part and the downward bias of the lower segment of that part, thereby reducing the charge density in that part. To improve the uniformity of the current density profile along the longitudinal dimension.

Referring to FIG. 7A, in some specific examples, the correction device 42 may be configured to apply a lateral electric field to the ion beam (that is, an electric field having a component along a lateral dimension of the ion beam) so as to cause the The ion beam is deflected laterally, for example, to change the propagation direction of the ion beam. More specifically, the correction device 42 may be configured such that each electrode system of the electrode pairs can be individually biased. For example, in this specific example, the voltage sources V1, ..., V20 may apply independent voltages (eg, electrostatic voltages) to the electrodes of the electrode pairs (see, for example, the voltage sources V1 and V11 are configured to apply independent voltages to the voltage source). Electrodes E1a and E1b) of electrode pair E1.

For example, the potential difference between opposite electrode pairs of one or more electrodes may be selected to provide a localized lateral deflection of one or more portions of the ion beam. For example, as shown in FIG. 7A, in this example, the voltage sources V2 and V12 apply different voltages v2 and v12 to the electrodes E2a and E2b (v12 <v2) in order to facilitate the passage between the two opposing electrodes. A part of the ion beam is locally deflected toward the electrode E2b. At the same time, the voltage sources V4 and V14 apply different voltages v4 and v14 to the electrodes E4a and E4b (v14> v4), so as to promote partial deflection of the ion beam passing between the two opposing electrodes toward the electrode E4a. In some specific examples, the potential difference between the two opposite electrodes may be in a range of about 0V to about 4kV.

In some cases, the entire ion beam can be laterally deflected by applying a voltage to all electrodes on one side of the ion beam and another voltage to all electrodes on opposite sides of the ion beam, such as To change the direction of its spread.

Referring to FIGS. 7B and 7C, in some specific examples, the correction device 42 may be configured to deflect the entire ion beam along the longitudinal dimension (ie, vertically along the y-axis). For example, as shown in FIG. 7C, the controller 44 may cause the power The voltage sources V1, ..., V10 apply a ramp voltage to the electrode pairs E1, ..., E10 to generate an electric field having a component along the longitudinal dimension of the ion beam (shown schematically in FIG. 7B as an arrow). , Which can promote the longitudinal deflection of the ion beam.

The controller 44 connected to the voltage sources V1, ..., V20 may, for example, determine the voltage to be applied to the electrodes based on a desired local or global deflection angle of one of the ion beams. The controller may determine the required voltage in a manner such as that based on the charge of the ions in the ion beam, a desired deflection angle. In some cases, the controller may implement voltage application to the electrode pairs of electrodes to provide local lateral and longitudinal deflections of the ion beam. For example, the voltage difference between different electrode pairs may, for example, promote local longitudinal deflection in the manner shown above with respect to FIG. 6, and the voltage difference between the electrode pairs may promote local lateral deflection.

Referring to FIG. 8A, in some specific examples, the correction device 42 may be configured to cause the ion beam to make an oscillating motion along its longitudinal dimension. The waveform generator 100 under the control of the controller 44 may apply a variable voltage to one or more of the electrode pairs to create a voltage having a longitudinal dimension (along the y-axis) along the ion beam. The changing electric field of the component, in turn, causes the ion beam to become deflected over time. In some cases, such a time-varying bias of the ion beam may be in the form of a periodic oscillation of the ion beam along its longitudinal dimension. In some cases, the amplitude of such an oscillation may be, for example, in the range of about 10 mm to about 20 mm.

For example, as shown schematically in Fig. 8B, the waveform generator may apply a triangular voltage waveform to the electrode pairs E1, ..., E10 to cause the ion beam to oscillate periodically along its longitudinal axis. Such "wobble" of the ion beam can improve the dose uniformity of the ions implanted in a substrate incident with the ion beam. The oscillating frequency can be based, for example, on the speed of movement of the substrate relative to the incident ion beam. Rate. In some specific examples, the oscillation frequency may be, for example, in a range of about 1 Hz to about 1 kHz.

Referring again to FIGS. 2A, 2B, and 2C, the deceleration / acceleration system 22 further includes a deceleration / acceleration element 46 that is separated from a downstream focusing element 48 to define a gap region 50 therebetween. The deceleration / acceleration element 46 includes two opposite equipotential electrodes 46a and 46b which provide a passage therebetween for the ion beam to pass through. Similarly, the focusing element 48 includes two equi-opposing electrodes 48a and 48b which provide a channel therebetween for the ion beam to pass through.

The application of a potential difference between the deceleration / acceleration element 46 and the focusing element 48 generates an electric field in the gap region to decelerate or accelerate the ions of the ion beam. Among other factors, it can be selected in a manner known to those skilled in the art based on the expected change in the energy of the plasma, the type of ions of the ion beam, and the specific application for which the ion beam is used The potential difference between the deceleration / acceleration element and the focusing element.

For example, in some implementations, a voltage in the range of about 0 to about -30 (negative 30) kV or in the range of about 0 to about +30 (positive 30) kV can be applied to such decelerations / accelerations The electrodes 46a / 46b and a voltage in the range of about 0 to about -5 (negative 5) kV can be applied to the focusing electrodes 48a / 48b.

Referring to FIG. 2C, in this specific example, the upstream surface (UF) of one or both of the focusing electrodes 48a / 48b is bent to generate an electric field component in the gap region to counteract the ion beam in the non-dispersion Divergence in a plane (along the longitudinal dimension of the ion beam). For clearer illustration, FIG. 2C shows an ion beam passing through the gap 50, the ion beam exhibiting divergence of ions in the non-dispersive plane near its longitudinal endpoint due to the mutual exclusion space charge effect. Curved section of the upstream ends of the focusing electrodes 48a / 48b The surface can be configured to help generate an electric field pattern that will apply a corrective force to such divergent ions to ensure that the ions of the ion beam travel substantially parallel. For example, the upstream end of the focusing electrode may have a substantially concave cross section (when viewed from the upstream direction) and have a radius of curvature in a 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 elbow 52 disposed on the downstream side of the focusing element 48 and separated by a gap 53 therefrom. A potential difference between the focusing element 48 and the electrostatic elbow (eg, one or more electrodes of the elbow) may generate an electric field in the gap 53 in order to reduce the divergence of the strip-shaped ion beam along its lateral dimension. In other words, the gap between the focusing element 48 and the electrostatic elbow 52 is used as a focusing lens to reduce the divergence of the ion beam along its lateral dimension. The voltage can be applied to the deceleration / acceleration element and the focusing element using one or more voltage sources under the control of the aforementioned controller 44 in a manner known in the art, for example.

In this specific example, the electrostatic elbow 52 includes an outer electrode 52a and an opposite inner electrode 52b. Different potentials may be applied to the outer electrode 52a and the opposite inner electrode 52b to promote the ion beam to be deflected when the ion beam passes through a lateral gap separating the electrodes. For example, the deflection angle of the ion beam may be in a range of about 10 degrees to about 90 degrees, for example, 22.5 degrees.

In this specific example, the electrostatic elbow further includes an intermediate electrode 52c, which is disposed downstream of the internal electrode 52b and is electrically isolated from the internal electrode 52b (for example, via a gap) to allow it to be applied to the internal electrode 52b. A voltage irrelevant to the internal electrode 52b is applied to the intermediate electrode 52c. For example, in this specific example, the external electrode 52a and the intermediate electrode 52c are kept at the same potential. In some specific examples, the voltage applied to the external electrode 52a may range from about 0 to about -20 (negative 20) kV. The voltage applied to and within the internal electrode 52b may be in a range of about -5 (negative 5) kV to about -30 (negative 30) kV.

The external electrode 52a includes an upstream portion (UP) and a downstream portion (DP), which are arranged at an acute angle with respect to each other to provide a curved section to the external electrode. Among other factors, the angle between the upstream portion and the downstream portion of the external electrode may be selected based on, for example, geometrical constraints, lateral divergence of the ion beam when the ion beam enters the deceleration / acceleration system. In this specific example, the angle between the upstream portion and the downstream portion of the external electrode is about 22.5 degrees. Although in this specific example, the upstream portion and the downstream portion integrally constitute the external electrode, in another specific example, the upstream portion and the downstream portion may be individual electrodes electrically coupled to be equipotential.

As described above, the potential difference between the outer electrode 52a and the inner electrode 52b generates an electric field in the space between those electrodes so as to deflect the ions of the ion beam. However, when the electrically neutral particles (neutral atoms and / or molecules) (if any) present in the ion beam have entered the electrostatic elbow, they are not biased and continue to travel in the direction of their propagation . As a result, the neutral particles or at least a part of them hit the downstream portion (DP) of the external electrode and are removed from the ion beam.

On the downstream side of the electrostatic elbow 52, another correction device 54 for adjusting the current density of the ion beam along its longitudinal dimension (in the non-dispersion plane) may be optionally disposed. In this specific example, the correction device 54 has a structure similar to that of the upstream correction device 42. In particular, the correction device 54 includes a plurality of spaced electrode pairs, such as the electrode pair shown in FIG. 5 with respect to the upstream correction device 42, which are stacked along the longitudinal dimension of the ion beam, each electrode pair being provided therebetween A lateral gap for the passage of the ion beam. Similar to the upstream correction device 42, each electrode pair of the second correction device 54 may be applied by applying a voltage to each electrode (e.g., via a phase Similar to the voltage sources V1,..., V10 of the correction device 42 shown in FIG. 5), the bias voltages are individually biased. In this manner, if desired, the second correction device 54 may locally bias one or more portions of the ion beam to further improve the uniformity of the current density of the ion beam along its longitudinal dimension. In this way, the two correction devices 42 and 54 can cooperatively ensure that the strip-shaped ion beam exiting from the deceleration / acceleration system 22 exhibits high current density uniformity along its longitudinal dimension.

The controller 44 is also connected to a voltage source for applying a voltage to the electrode pair of the second correction device 54. The controller can determine the voltages applied to the electrode pairs and can cause those voltage sources to apply those voltages to the electrode pairs in a more detailed manner below.

Similar to the upstream correction device 42, the second downstream correction device 54 may be configured to cause a lateral deflection of the ion beam and / or an oscillating movement of the ion beam along its longitudinal dimension in the manner described above. Furthermore, the downstream correction device 54 may be configured to cause the longitudinal (vertical) deflection of the entire ion beam, for example, in the manner described above with respect to the upstream correction device 42.

As described above, in this specific example, the external electrode 52a and the intermediate electrode 52c are maintained at the same potential. This can improve and better prevent any disturbance of the ion beam caused by the unwanted electric field component when the ion beam passes through the gap between the electrostatic elbow and the second correction device.

In this specific example, the electrode pair of the downstream second correction device 54 is offset from the electrode pair of the upstream correction device 42 along the longitudinal dimension of the ion beam. In other words, each electrode pair of the correction device 54 is offset vertically (along the longitudinal dimension of the ion beam) relative to an individual electrode pair of the upstream correction device 42. Such an offset may be, for example, one-half (pixels) of the longitudinal height of the electrodes of the correction devices. Half the size). In this way, the correction devices 42 and 54 can cause finer resolution (eg, a resolution corresponding to half the pixel size) to cause local deflections of various parts of the ion beam.

In this specific example, the correction devices 42 and 54 are appropriately separated from each other to limit the voltage applied to their electrodes to less than about 2 kV, which can improve the stability of the operation of the correction devices and can also The equal electrode pairs are closely aligned along the longitudinal dimension.

Although two correction devices are used in this specific example, only a single correction device can be used in other specific examples to improve the uniformity of the current density of the ion beam along its longitudinal dimension. For example, the correction device can be used 42 or this correction device 54. For example, in some specific examples of decelerating the ion beam received from the analysis magnet, only the downstream correction device 54 may be used.

With continued reference to FIGS. 2A and 2B and 2C, another focusing element 56 is optionally disposed on the downstream side of the second correction device 54 and the other focusing element 56 is separated from the second correction device 54 by a gap 58. Similar to the upstream focusing element 48, the second focusing element 56 includes a pair of opposing electrodes 56a and 56b that provide a passage therebetween for the passage of the ion beam. The potential difference between one or more electrode pairs of the second correction device 54 and the second focusing electrodes 56a / 56b will cause an electric field in the gap 58, which can reduce the electric field when the ion beam passes through the gap. The ion beam diverges along its longitudinal dimension.

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

The system further includes a grounding element 60 having a pair of opposite electrical ground electrodes 60a and 60b, which are disposed on the second focusing electrodes. The downstream sides of 56a and 56b are separated from each other to form a gap 62. The opposing ground electrodes 60a and 60b constitute an electrically grounded duct through which the ion beam exits the deceleration / acceleration system toward the terminal station 24 via the electrically grounded duct.

In some specific examples, the deceleration / acceleration system 22 lacks the second correction device 54 and the second focusing element 58.

The potential difference between the focusing electrodes 56a and 56b and the ground electrodes 60a and 60b results in the generation of an electric field component in the gap 62. When the ion beam passes through the gap, the ion beam can be reduced along its Horizontal dimension divergence. Furthermore, in this specific example, for example, similar to the upstream faces (edges) of the electrodes 48a / 48b, the upstream faces (edges) of the electrodes 60a and 60b are bent to reduce the ion beam along its Vertical dimension divergence. Therefore, the lens gaps 58 and 62 together provide a second focusing lens to reduce the divergence of the ion beam along its lateral and longitudinal dimensions.

In many specific examples, the output band-shaped ion beam leaving the deceleration / acceleration system presents along its longitudinal dimension a film having a length equal to or less than about 5% or equal to or less than about 4% or equal to or less than about 2% and A current density profile that preferably has an RMS non-uniformity of less than about 1%. Such a ribbon-shaped ion beam may have a longitudinal length that is larger than a diameter (for example, greater than about 300 mm or greater than about 450 mm) of a substrate on which the ion beam is incident. Therefore, linear movement of the substrate along the lateral dimension can result in implantation of a substantially uniform dose of ions in the substrate.

In some specific examples, the output band ion beam can be used to implant an ion dose in a range of about 10 ¹² to about 10 ¹⁶ cm ^-2 into a substrate. In some such specific examples, the current of the ribbon ion beam incident on the substrate may be, for example, about tens of microamperes (for example, about 20 microamperes) to about tens of milliamperes (for example, about 60 milliamperes). Range), for example, in the range of about 50 microamps to about 50 milliamps, or in the range of about 2 milliamps to about 50 milliamps.

In some specific examples, the voltage applied to these correction devices 42 and 54 can be determined in the following manner. Initially, the current density of a band-like mass selective ion beam (also referred to herein as an uncorrected ion beam) leaving the analysis magnet 20 can be measured. For example, the above objective is achieved by passing the uncorrected ion beam through the deceleration / acceleration system 22 under a voltage applied only to the electrode of the electrostatic elbow, so that the substantially undisturbed ion beam travels to the terminal station. .

A current measurement device disposed in the terminal station can be used to measure the current density profile of the uncorrected ion beam. For example, FIG. 9 outlines a profiler 102 that is telescopically disposed in a terminal station 24 of the ion implantation system. Various beam current profilers can be used. For example, in some specific examples, the beam profiler may include a series of Faraday cups to measure the current profile of the ion beam as a function of height. In other embodiments, the ion beam profiler may include a current measurement plate that can be moved across the ion beam. The ion beam profiler is connected to the controller 44 to provide information about the current profile of the ion beam along its longitudinal dimension. The controller 44 may use this information to determine the necessary voltages to be applied to these correction devices and / or other elements (eg, focusing elements). For example, the controller can use this information to determine the voltage applied to the electrode pairs of these correction devices to improve the uniformity of the current density profile of the ion beam along its longitudinal dimension.

For example, FIG. 10A shows a histogram depicting the ion current of a simulated uncorrected phosphorus ion beam with energy of 40 keV and a total current of 30 mA in some height bins. This histogram shows local non-uniformities in the current density of the ion beam relative to a uniformity window. Here In the example, the uncorrected ion beam exhibits an ion current with a block height of about 12.5% in different height blocks.

Referring again to FIG. 9, the controller 44 may receive information about the current density profile of the uncorrected ion beam from the ion beam profiler 102 (for example, the information shown in the above histogram) and may use the information to determine A voltage applied to an electrode pair of one of the correction devices (for example, in the example shown in FIGS. 10A, 10B, and 10C, the downstream correction device 54 is initially configured) to provide the ion beam in its longitudinal direction First correction of current density of dimensions.

In some specific examples, the controller can compare the measured current in each height window with a reference value. If the difference between the measured current and the reference value exceeds a critical value, for example, 1 or 2 percent, the controller may cause one or more voltage sources to apply voltage to one or more voltages corresponding to that height window. The ion beam portion passes through the electrode pair therebetween so that the current in that portion is closer to the reference value. As detailed above, this can be achieved by causing the ion beam to be locally deflected along its longitudinal dimension.

For example, the controller may cause a voltage source coupled to the electrode pair of the second correction device 54 to apply the voltage shown in FIG. 10B to the electrode pairs in order to defocus the ion beam at its center. And focus the ion beam at its upper edge. For example, a voltage may be applied to pass a portion of the ion beam corresponding to a height window of 60-90 mm through an electrode therebetween to reduce the current density in this portion. In this way, the uniformity of the current density of the ion beam can be improved.

Then, the partially corrected ion beam corrected by one of the correction devices (for example, the downstream correction device in this example) may be measured in the manner described above for measuring the current density of the uncorrected ion beam in the correction. Current density profile.

For example, the histogram shown in FIG. 10B depicts the simulated ion current as a function of a height window along the longitudinal dimension of the ion beam obtained by using only the second correction device to improve the Correct the ion beam current density. This part of the corrected ion beam presents an RMS deviation of about 3.2% of the ion beam current within the uniformity window (compared to the 12.5% change shown by the uncorrected ion beam, which is an improvement).

Referring again to FIG. 9, the controller 44 may receive information about the current density profile of the partially corrected ion beam in order to determine the voltage applied to the electrode pair of the upstream correction device 42 to further improve the uniformity of the ion beam profile. . In other words, the upstream correction device can provide fine correction of the ion beam profile.

For example, FIG. 10C shows that a voltage can be applied to the first correction device 42 to further improve the uniformity of the ion beam profile within the uniformity window. This figure also presents a histogram depicting a simulated cross section of the ion beam current when the first and second correction devices 42 and 54 are used to correct the uniformity of the uncorrected ion beam having the cross section shown in FIG. 10A. . This histogram shows that the combined correction effect of the two correction devices results in a current density profile with an RMS deviation of the ion current of about 1.2% within the uniformity window. In other words, in this example, the combined correction effect of the two correction devices results in an improvement in the uniformity of the current density profile of the ion beam along the longitudinal dimension by about an order of magnitude.

In other specific examples, the upstream correction device 42 may be configured first to provide a rough correction of the current density profile of the band ion beam leaving the mass analyzer, and then the downstream correction device 54 may be configured to provide the Finer correction of the current density profile of the ion beam.

As mentioned above, the deceleration / acceleration system can be configured in various ways. 统 22. For example, in some specific examples, the deceleration / acceleration voltage may be set to zero, so that the system 22 is only used as a calibration system without promoting deceleration and / or acceleration of ions in the ion beam.

Various ions can be implanted into various substrates using an ion implantation system according to the present teachings. Some examples of ions include, but are not limited to, phosphorus ions, arsenic ions, boron ions, molecular ions like BF ₂ ⁺ , B ₁₈ H _x ⁺ and C ₇ H _x ⁺ . Some examples of substrates include, but are not limited to, silicon, germanium, epitaxial (e.g., polycrystalline silicon) wafers, silicon-on-insulator (SIMOX) wafers, ceramic substrates like SiC or SiN, solar cells, and production A substrate used in a flat panel display. Some examples of the shape of the substrate include a circle, a square, or a rectangle.

In some specific examples, an electrostatic bend can be implemented by using three pairs of series electrodes arranged on the downstream side of an acceleration / deceleration system. As described in more detail below, when the acceleration / deceleration system is operated in a deceleration mode, a receiving ion beam is decelerated at a reduction ratio of at least 2 (for example, at a reduction ratio in a range of about 5 to about 100). Such an implementation of the electrostatic elbow can be particularly advantageous. The term reduction ratio as used herein means the ratio of the energy of the ion beam entering the reduction system to the energy of the ion beam leaving the reduction system (i.e., the energy of the ion beam received by the reduction system relative to the The ratio of the energy of the decelerated ion beam).

11A, 11B, and 11C schematically depict an ion implantation system 1100 according to one such specific example. As described in more detail below, the ion implantation system 1100 is similar to the ion implantation system 10 shown above with respect to FIGS. 2A, 2B, and 2C, except that the electrostatic elbow is implemented with three pairs of electrostatic bias electrodes. More specifically, similar to the above-mentioned ion implantation system 10, the ion implantation system 1100 includes the ion source 12 for generating an ion beam, and the extraction electrode 14 which is biased with electricity to assist the ions The beam is drawn from the ion source; the suppression electrode 16 is biased with electricity to prevent the neutralization of electrons from flowing back; the focusing electrode 18 is biased with electricity to reduce the divergence of the ion beam; and the ground electrode 19, It defines the reference ground for this ion beam. The analysis magnet 20 is disposed downstream of the focusing electrode 18 to receive the band-shaped ion beam and generate a mass selective ion beam.

The ion implantation system 1100 further includes a deceleration / acceleration system 200 including a slit 202 for receiving the mass selective ion beam; and a correction device 204 similar to the correction device described above. The deceleration / acceleration system 200 further includes a deceleration / acceleration element 206 that is separated from a downstream focusing element 208 to define a gap 210 therebetween. As described above with respect to the ion implantation system 10, the deceleration / acceleration element 206 includes two opposite equipotential electrode portions 206a and 206b, which provide a passage therebetween for the passage of the ion beam. In this specific example, the electrode portions 206a and 206b are connected at their top and bottom ends to form a rectangular electrode. Likewise, the focusing element 208 includes two equipotential electrode portions 208a and 208b, which provide a passage therebetween for the passage of the ion beam.

The application of a potential difference between the deceleration / acceleration element 206 and the focusing element 208 generates an electric field in the gap region 210 in order to decelerate or accelerate the ion beam. In this specific example, when operating in the deceleration mode, the potential applied between the deceleration / acceleration element 206 and the focusing element 208 may be a reduction ratio of at least 2 (for example, in the range of about 5 to about 100) ) Causes the ion beam passing through the gap 210 to decelerate.

For example, in order to achieve a reduction ratio, a voltage in a range of approximately -5kV to approximately -60kV may be applied to the electrode portions 206a and 206b of the deceleration / acceleration element 206 and may be applied between approximately 0V to approximately -30kV (minus 30kV ) To the electrode portions 208a and 208b of the focusing element 208.

In this specific example, an electrostatic elbow 212 (here, also referred to as E-bend 212) including three electrode pairs (214, 216, and 218) is disposed downstream of the focusing element 208 to receive the ion Beam and bias the ion beam. However, when the electrically neutral particles (neutral atoms and / or molecules) (if any) present in the ion beam have entered the electrostatic elbow, they are not biased and continue to travel in the direction of their propagation . Similar to the previous specific example, the electrostatic elbow can deflect the ion beam at an angle (for example, 22.5 degrees) in a range of about 10 degrees to about 90 degrees.

The first electrode pair 124 includes an inner electrode 214b and an outer electrode 214a, which are separated to allow the ion beam to pass therebetween. The second electrode pair 216 also includes an inner electrode 216b and an outer electrode 216a, which are separated to allow the ion beam to pass therebetween. Similarly, the last electrode pair 218 includes an inner electrode 218b and an outer electrode 218a, which are separated to allow the ion beam to pass therebetween. At an angle relative to the individual electrodes of the first and last electrode pairs (for example, half of the total deflection angle of the ion beam, the total deflection angle is, for example, a deflection in a range of about 5 to about 45 degrees Each electrode of the second electrode pair is arranged in an angle) manner.

As described in more detail below, the electrodes of the first electrode pair 214 are maintained at a potential that is less than the potential held by the electrodes of the second electrode pair 216. Furthermore, each electrode of the last electrode pair 218 is maintained at a potential that is less than the potential held by any of the electrodes of the second electrode pair 216. In addition, in this specific example in which the ion beam includes positively charged ions, the inner electrode of each of the electrode pairs is maintained at a potential that is less than the potential held by the individual outer electrodes of that electrode pair in order to generate a The electric field of the ion beam is bent as the ion beam passes between the electrodes. In other words, the internal electrode 214b is maintained at a lower potential than the external electrode 214a, the internal electrode 216b is maintained at a lower potential than the external electrode 216a, and the internal electrode 218b is maintained at a lower electrical potential than the external electrode 218a. Bit.

More specifically, 11B, the in this particular embodiment, the first electrode 214a and the electrode 214 than the final electrode 218 than the electrode 218a is maintained at the same potential (V ₁₎ and the first electrode pair 214, The inner electrode 214b and the inner electrode 218b of the last electrode pair 218 are maintained at the same potential (V ₂ ), where V _{2 is} less than V ₁ (for example, V ₂ may be -25 kV and V ₁ may be -15 kV). Furthermore, the inner electrode 216b of the second electrode pair 216 is electrically grounded and the outer electrode 216a of the second electrode pair is maintained at a potential V ₃ , where V _{3 is} greater than each of V ₁ and V ₂ .

For example, the potential V ₁ may be in a range of 0 V (zero volts) to about -20 kV, and the potential V ₂ may be in a range of 0 V (zero electrical volts) to about -30 kV. Further, the potential V ₃ may be in a range of 0 to about +30 kV.

Referring to FIG 11D, in this particular embodiment, a voltage source 221 is applied to the voltage V ₁ is such electrodes 214a and 218a, 223 applies the voltage V ₂ to these electrodes 214b and 218b, and a voltage source 225 is applied to a voltage source The voltage V _{3 is applied} to the electrode 216a. In other specific examples, the voltage sources can apply different voltages to the electrodes. A controller 227 can control the voltage sources to apply a desired voltage to the electrodes.

The arrangement of the three electrode pairs (214, 216, and 218) on the downstream side of a deceleration system in an ion beam line as described herein may provide some advantages. Specifically, when the reduction system is operated so as to provide a high reduction ratio, such as a reduction ratio greater than about 2, the ion beam can be made to experience a strong focusing effect when it traverses the reduction gap (for example, the aforementioned gap 210). ). Such a strong focus can produce an over-focused ion beam that may exhibit significant divergence ("blow-up") and thus impact the electrode or other Those electrodes of the downstream components.

Using the segmented electrode pairs 214, 216, and 218 as the electrostatic elbow can alleviate this problem. More specifically, the segmented electrode pairs 214, 216, and 218 exhibit strong focusing capabilities to correct the high divergence of the ion beam caused by the ion beam undergoing strong focusing by the deceleration system, so that there is no significant loss of ions (Preferably without any loss) under the electrodes of the elbow or those of other downstream components to ensure that the ion beam will leave the electrostatic elbow and reach the downstream wafer. For example, when the ion beam enters the gap 213 between the first electrode pair and the second electrode pair, the ion beam may be defocused. When the ion beam enters the space between the electrodes of the second electrode pair 216 and the gap 215 between the second electrode pair and the last electrode pair, the ion beam experiences a strong focusing force, but in some cases, the ion The beam will experience a small focusing force in this gap 215.

For further clarity, FIG. 12A shows a theoretical simulation of an ion beam passing through a deceleration system and a downstream traditional electrostatic elbow consisting of two spaced electrodes. Specifically, in this specific example, the deceleration system includes two electrode pairs 1200 and 1201, where the electrode pair 1200 is maintained at a voltage of -29.5 kV and the electrode pair 1201 is maintained at a voltage of -5 kV. Furthermore, the inner electrode 1202 of the electrostatic elbow is maintained at a voltage of -0.75 kV and the outer electrode 1203 of the electrostatic elbow is maintained at a voltage of -0.47 kV. In addition, it is assumed that the ion beam entering the deceleration system includes positively charged ions having an energy of 30 keV. The ion beam passes through the deceleration system to reduce the energy of the ion beam to 0.5 keV. In other words, the reduction system exhibits a reduction ratio of 60. The simulation results show that this high reduction ratio causes the ion beam to be over-focused at the focus A, so that the ion beam appears to cross and diverge quickly enough to hit the external electrode and downstream components of the electrostatic elbow at its distal end.

In comparison, FIG. 12B shows a theoretical simulation of an electrostatic elbow that is passed through a deceleration system and then through 3 individual electrode pairs. Similar to the previous simulation, the deceleration system is composed of two electrode pairs 1200 and 1201 maintained at a voltage of -29.5kV and -5.5kV, respectively. In this simulation, the electrostatic elbow is implemented in the manner described above by using three electrode pairs 1204, 1205, and 1206, where the electrodes within the first and last electrode pairs 1204 and 1206 are maintained at a potential of -0.75 kV And their external electrodes are maintained at a potential of -0.68kV. The inner electrode of the second electrode pair is grounded and its outer electrode is maintained at a potential of +0.73 kV. Similar to the previous simulation, the ion beam was connected into the reduction system with an energy of 30 keV and exited the reduction system with a reduced energy of 0.5 keV (corresponding to a reduction ratio of 60). Although similar to previous simulations, the high reduction ratio caused the ion beam to overfocus and thus cause it to diverge when it entered the electrostatic elbow, but the electrostatic elbow of this teaching corrects this divergence so that there is no ion loss Make sure that the ion beam leaves the electrostatic elbow and the downstream components under, for example, the electrodes of the electrostatic elbow or those of the downstream components.

Another advantage of the electrostatic elbow implemented by using the above three electrode pairs is that it can help focus the high current ion beam. In an E-bend that applies a high voltage to an electrode of the elbow, there are usually a few background electrons in the elbow. The absence of these electrons makes it difficult to neutralize the charge of the ion beam, where the charge neutralization can inhibit the ion beam from "spreading".

Specifically, in the conventional E-bend, because the voltage required to provide such an E-bend with sufficient focusing ability will be very high (for example, -30kV to -60kV), the problem of "spreading" the ion beam is high for high voltages. Ion beam energies (eg, energies greater than about 30 ekV) and high ion beam currents can become apparent.

For example, FIG. 13A shows an energy source with 30 keV and 25 mA. A simulated ion beam of electric current passes through a conventional E-bend 1300 having an internal electrode 1300a maintained at a potential of -25kV and an external electrode 1300b maintained at a potential of -12kV. The ion beam has a width of 169 mm on a downstream wafer. Simulation results show that the "spreading" of the ion beam causes ion loss and a wider ion beam spot on the downstream wafer. The ion beam spot must be larger than the wafer scanning and reduce process throughput.

In comparison, FIG. 13B shows a simulated ion beam with an energy of 30 keV and a current of 25 mA passing through an E-bend according to one of the teachings. The E-bend is composed of three electrode pairs 1302, 1304, and 1306. The electrodes inside the electrode pairs 1302 and 1306 were maintained at a voltage of -25 kV and those outside the electrode pairs were maintained at a voltage of -13.65 kV. The inner electrode of this electrode pair 1304 is grounded and its outer electrode is maintained at a voltage of + 16kV. The simulation results show that the E-bend composed of 3 individual electrode pairs prevents the ion beam from spreading and allows the ion beam to cross the elbow and the downstream components without ion loss.

Referring again to FIGS. 11A, 11B, and 11C, in this specific example, the electrode 218a includes an internal electrode portion 219 disposed downstream of the internal electrode 218b and electrically isolated from the internal electrode portion 218 (eg, via a gap). In this specific example, the electrode portion 219 is coupled to the electrode portion outside the electrode 218a at its top and bottom ends so as to form a complete rectangular outlet electrode, and the complete rectangular outlet electrode is at the exit of the E-bend. A substantially uniform potential is defined near the periphery of the band-shaped ion beam at the same position so as to maintain the band shape of the ion beam. The ion implantation system 1100 further includes another optional correction device 220 configured on the downstream side of the electrostatic elbow to adjust the current density of the ion beam along its longitudinal dimension (in the non-dispersed plane). The other focusing element 222 is optionally disposed on the downstream side of the second correction device. The ion implantation system further includes opposing ground electrode portions 224a and 224b, and the opposing ground electrode portions 224a and 224b constitute a The ion beam passes through an electrically grounded conduit to enter an end station 226 in which a wafer 228 is held in the end station 226 so as to expose it to the ion beam.

The use of an E-bend consisting of these three individual electrode pairs is not limited to an ion implantation system using a ribbon ion beam. More precisely, such an E-bend can also be used on the downstream side of a deceleration system in, for example, other ion implantation systems using circular ion beams. Another aspect of the present teaching relates to the use of a split lens as an exit lens disposed on the downstream side of an electrostatic elbow of the ion implantation system.

For example, FIGS. 14A and 14B are partial schematic diagrams of an implantation system 300 similar to the implantation system 10 described above. The implantation system 300 includes a mass selective ion beam from an upstream mass analyzer (not shown).的 孔 302。 The hole 302. The ion implantation system 300 further includes a correction device 304, a deceleration / acceleration system 306 disposed on the downstream side of the correction device 304, and an electrostatic elbow 308 disposed on the downstream side of the deceleration / acceleration system. In this specific example, the electrostatic elbow includes a curved external electrode 308a and a curved internal electrode 308b, wherein the application of a voltage difference between these electrodes causes an electric field to be generated in the space therebetween, so that an The passing ion beam is bent.

Unlike the above-mentioned ion implantation system 10, in this specific example, a pair of tangent lenses 310 are arranged on the downstream side of the electrostatic elbow 308. The tandem lens 310 includes a pair of electrodes 312 and another pair of electrodes 314, wherein the electrode pair 312 includes a curved downstream end surface 312a and the electrode pair 314 includes a curved upstream end surface 314a. The two curved end faces of the electrode pairs are separated from each other by a bending gap 316 therebetween. In some specific examples, each of the curved end faces of the lenses 312 and 314 is characterized by a radius of curvature in a range of about 250 mm to about 1000 mm (for example, for electrode pair 312, (Shown as R1).

The electrode pairs 312 and 314 can be independently biased to different potentials. For example, a potential V ₁ may be applied to the electrode pair 312 and another potential V ₂ may be applied to the electrode pair 314. If V ₁ and V ₂ are selected such that V ₁ > V ₂ , a strong vertically de-focusing lens can be formed. On the other hand, if V ₁ <V ₂ , a strong vertically focusing lens can be formed. For example, the potentials V ₁ and V ₂ may be in a range of about 0V to about -20 kV. In some implementations, even though the electrode of the electrostatic elbow is maintained at a high potential, V ₁ and V ₂ may be selected to be close to the ground potential (for example, in a range of about 0V to about -5kV). This can help reduce and better remove energy contamination when operating the ion implantation system in a deceleration mode.

More specifically, in some cases, when a conventional lens is used on the downstream side of the E-bend instead of the dicing lens, it may be necessary to apply a high voltage to the electrode of the lens in order to provide a high-energy ion beam (for example, Ion beams with an energy in the range of about 30 keV to 60 keV) for vertical focusing. When the ion beam passes through the lens, such a high voltage will cause a temporary increase in the energy of the ion beam, which in turn will cause some ions to experience a charge exchange reaction as they cross the lens. Because the lens is usually disposed in a straight line of sight with respect to a downstream wafer, such a charge exchange reaction will result in the formation of neutral atoms / molecules implanted in the downstream wafer. In addition, the application of high voltage to the electrodes of the lens can cause arcing, which can cause transient instability of the ion beam.

A tangent lens such as the above-mentioned lens 310 can improve the vertical focusing ability of the E-bend, while reducing and better removing ion beam contamination caused by arc beam instability and generation of neutral atoms / molecules . For example, the radius of curvature of the end face of the electrode of the tangent lens may be sufficiently small (for example, depending on the height of the ion velocity, in the range of about 250mm to about 500mm, for example, for an ion beam of 300m high, the radius of curvature may be Is about 450mm) to allow focusing / defocusing of the ion beam vertically at lower lens voltages. For example, for the 60keV beam, V ₁ may be about -10Kv 0V and V ₂ may be, they are much lower than in the conventional lens system to reach the voltage required for focusing effect similar.

With continued reference to FIGS. 14A and 14B, a correction device 317 is disposed downstream of the tandem lens 310 to adjust the current density of the ion beam along its longitudinal dimension (in the non-dispersion plane). A further focusing element 318 may be optionally arranged on the downstream side of the second correction device. The ion implantation system further includes a ground electrode 320, which constitutes an electrical grounding duct through which the ion beam can pass to enter a terminal station (not shown), wherein a wafer (not shown) is held in the terminal station, In order to expose it to the ion beam.

Another advantage of using the tandem lens 310 is that it allows space charge neutralization to occur immediately after the correction device 317. In contrast, in a system using a conventional lens like lens 318 instead of the tandem lens 310, the beginning of space charge neutralization ion beam transport may be moved deeper into the grounded catheter electrode 320, which may be higher The current causes the ion beam to spread.

It is also possible to use a tangent lens (for example, the above-mentioned tangent lens 310) on the downstream side of an E-bend (for example, the above-mentioned E-bend 212) including three electrode pairs. For example, FIG. 15 shows a partial schematic diagram of an ion implantation system 400 including a slit 402 for receiving an ion beam, a correction device 404, a deceleration / acceleration system 406, a E-bend 408 consisting of three individual electrode pairs, a pair of tangential lenses 410, another correction device 412, a poly A focal electrode 414 and a ground electrode 416 for providing a conduit for the ion beam to enter a terminal inside which a wafer is disposed. The voltage applied to the electrodes of the E-bend 408 may be in the range described above with respect to the E-bend 212.

Those having ordinary skill in this technical field will perceive that various changes can be made to the above-mentioned specific embodiments without departing from the scope of the present invention.

10‧‧‧ ion implantation system

12‧‧‧ ion source

14‧‧‧ lead-out electrode

16‧‧‧Suppression electrode

18‧‧‧ focusing electrode

19‧‧‧ ground electrode

20‧‧‧ Analysis Magnet

20a‧‧‧Variable size mass analysis hole

22‧‧‧correction system (deceleration / acceleration system)

24‧‧‧Terminal

25‧‧‧ substrate holder

26‧‧‧ substrate

42‧‧‧calibration device

46‧‧‧Deceleration / acceleration element

48‧‧‧ focusing element

50‧‧‧Gap area

52‧‧‧Static elbow

54‧‧‧correction device

56‧‧‧ focusing element

60‧‧‧ grounding element

Claims (20)

An ion implantation system includes: a deceleration system configured to receive an ion beam and decelerate the ion beam with a deceleration ratio of at least 2; and an electrostatic elbow disposed on a downstream side of the deceleration system, Used to cause the ion beam to be deflected; the electrostatic elbow includes: a first electrode pair arranged on the downstream side of the deceleration system to receive the decelerated ion beam, the first electrode pair has one spaced apart An internal electrode and an external electrode to allow the ion beam to pass therebetween; a second electrode pair disposed on the downstream side of the first electrode pair and having an internal electrode and an external electrode spaced apart to allow the An ion beam passes therebetween; and a final electrode pair disposed on the downstream side of the first electrode pair and having an inner electrode and an outer electrode spaced apart to allow the ion beam to pass therethrough, wherein the electrodes The pairs are configured to be independently biased. The ion implantation system of claim 1, wherein each electrode of the last electrode pair is maintained at a potential smaller than the potential held by any electrode of the second electrode pair and the electrode of the first electrode pair is relative to the first electrode pair. The electrodes of the two electrodes are kept at a low potential. The ion implantation system of claim 1, wherein the reduction ratio is in a range of about 5 to about 100. The ion implantation system of claim 2, wherein the inner electrode of each of the electrode pairs is maintained at a potential that is less than the potential held by the individual outer electrodes of that electrode pair. The ion implantation system of claim 2, wherein the outer electrodes of the first and last electrode pairs are maintained at a first potential (V ₁ ) and the inner electrodes of the first and last electrode pairs are maintained at a second Potential (V ₂ ). The ion implantation system of claim 5, wherein the inner electrode of the second electrode pair is electrically grounded and the outer electrode of the second electrode pair is maintained at a third potential (V ₃ ). The ion implantation system of claim 5, wherein V _{1 is} higher than V ₂ . The ion implantation system of claim 1, wherein the speed reduction system includes a speed reduction element separated from a downstream focusing element so as to define a gap therebetween. The ion implantation system of claim 1, further comprising an ion source for generating the ion beam. The ion implantation system as claimed in claim 1, further comprising an analysis magnet disposed downstream of the ion source and upstream of the deceleration system, for receiving the ion beam generated by the ion source and generating a mass-selective ion bundle. The ion implantation system according to claim 1, further comprising a tangential lens disposed on a downstream side of the electrostatic elbow, the tangential lens comprising: a first electrode pair having a curved downstream end surface; a second electrode The pair has a curved upstream end surface, wherein the end surfaces of the two electrode pairs are separated from each other to form a gap therebetween. The ion implantation system of claim 11, wherein the first and second electrode pairs of the tangent lens are configured to be independently biased. The ion implantation system of claim 12, wherein the first and second electrode pairs of the tangent lens are biased to generate an electric field in the gap to focus the ion beam passing through the tangent lens. . An ion implantation system includes: an electrostatic elbow for biasing an ion beam; the electrostatic elbow includes: A first electrode pair having an internal electrode and an external electrode separated to allow the ion beam to pass therebetween; a second electrode pair disposed on a downstream side of the first electrode pair and having a partition An internal electrode and an external electrode, to allow the ion beam to pass therebetween; and a final electrode pair, which is arranged on the downstream side of the second electrode pair and has an internal electrode and an external electrode separated, To allow the ion beam to pass therethrough, wherein each electrode of the last electrode pair is maintained at a potential that is less than the potential held by any electrode of the second electrode pair and the electrode of the first electrode pair is opposite the second electrode The opposing electrodes are held at a lower potential, and the inner electrode of each of these electrode pairs is maintained at a potential that is less than the potential held by the individual outer electrodes of that electrode pair. The ion implantation system of claim 14, wherein the outer electrodes of the first and last electrode pairs are maintained at a first potential (V ₁ ) and the inner electrodes of the first and last electrode pairs are maintained at a second Potential (V ₂ ). The ion implantation system of claim 15, wherein the inner electrode of the second electrode pair is electrically grounded and the outer electrode of the second electrode pair is maintained at a third potential (V ₃ ). The ion implantation system of claim 16, wherein V _{1 is} higher than V ₂ . An ion implantation system includes: an electrostatic elbow for receiving an ion beam and causing the ion beam to be deflected; a pair of tangential lenses configured at a downstream side of the electrostatic elbow, the pair of tangent lenses including : A first electrode pair having a curved downstream end face; a second electrode pair having a curved upstream end face, wherein the first and second electrode pairs are configured to be independently biased, and the two The end faces of the electrode pairs are separated from each other to form a gap therebetween. The ion implantation system of claim 18, wherein the first and second electrode pairs are biased so as to generate an electric field in the gap to focus the ion beam passing through the tandem lens. The ion implantation system of claim 18, wherein the electrostatic elbow comprises: a first electrode pair, which is arranged on the downstream side of the deceleration system to receive the deceleration ion beam, the first electrode pair has an inner An electrode and an external electrode are separated from each other to allow the ion beam to pass therebetween; a second electrode pair is disposed on the downstream side of the first electrode pair and has an internal electrode and an external electrode spaced apart to Allowing the ion beam to pass therebetween; and a final electrode pair disposed on the downstream side of the first electrode pair and having an internal electrode and an external electrode spaced apart to allow the ion beam to pass therethrough, wherein the The equal electrode pairs are configured to be independently biased.