Electrostatic filter for reducing particle generation

Abstract

Approaches for reducing particle generation in electrostatic lenses are described herein. In some embodiments, an ion implantation system can include an electrostatic lens including an entrance for receiving an ion beam and an exit for delivering the ion beam toward a target, the electrostatic lens including a first terminal electrode, a first suppression electrode, and a first ground electrode disposed along a first side of the ion beam line, the first ground electrode being grounded and disposed adjacent to the exit. The electrostatic lens may further include a second terminal electrode, a second suppression electrode, and a second ground electrode disposed along a second side of the ion beam line, the second ground electrode being grounded and disposed adjacent to the exit. The implantation system may further include a power supply operable to provide a voltage and a current to the electrostatic lens to control the ion beam.

Description

Technical Field

[0001]

[0001] The present disclosure generally relates to semiconductor processing, and more particularly to an electrostatic filter for reducing particle generation.

Background Art

[0002]

[0002] Ion implantation is a process of introducing dopants or impurities into a substrate by bombardment. In semiconductor manufacturing, dopants are introduced to change electrical, optical, or mechanical properties. For example, dopants can be introduced into an intrinsic semiconductor substrate to change the type and level of conductivity of the substrate. In the manufacture of integrated circuits (ICs), an accurate doping profile improves the performance of the IC. To achieve a desired doping profile, one or more dopants can be implanted in the form of ions with various dose amounts and various energy levels.

[0003]

[0003] An ion implantation system can include an ion source and a series of beamline components. The ion source may include a chamber in which desired ions are generated. The ion source may also include a power supply and an extraction electrode assembly disposed near the chamber. The beamline components can include, for example, a mass analyzer, a first acceleration / deceleration stage, a collimator, and a second acceleration / deceleration stage. Like a series of optical lenses for manipulating an optical beam, the beamline components can filter, focus, and manipulate ions or an ion beam to have a desired species, shape, energy, and other qualities. The ion beam can pass through the beamline components and be directed towards a substrate or wafer attached to a platen or clamp. The substrate can be moved (e.g., translated, rotated, tilted) in one or more dimensions by a device sometimes called a roplat.

[0004]

[0004] An ion implantation apparatus generates a well-defined and stable ion beam for various different ion species and extraction voltages. When operating for several hours using source gases (such as AsH3, PH3, BF3, and other species), eventually, the beam components cause deposits to form on the beam optical components. Also, the beam optical components within the line-of-sight of the wafer become coated with residues from the wafer, including Si and photoresist compounds. These residues accumulate on the beam line components and cause DC potential spikes during operation (such as in the case of electrically biased components). Eventually, the residues flake off, increasing the likelihood of particle contamination on the wafer.

[0005]

[0005] One way to prevent the effects of material accumulation is to intermittently replace the beam line components of the ion implantation system. Alternatively, the power to the ion source may be turned off and the vacuum within the system released, etc., and the beam line components may be manually cleaned. After replacing or cleaning the beam line components, the system is evacuated and powered on to become operational. Therefore, these maintenance processes can be very time-consuming. Also, during the maintenance process, the beam line components are not used. Therefore, performing the maintenance process frequently may lead to a decrease in throughput and an increase in the overall manufacturing cost.

Summary of the Invention

[0006]

[0006] In one approach, the ion implantation system can include an electrostatic lens that includes an inlet for receiving an ion beam and an outlet for directing the ion beam toward a target. The electrostatic lens includes a first terminal electrode, a first suppression electrode, and a first ground electrode disposed along a first side of the ion beam line. The first ground electrode is grounded and is disposed adjacent to the outlet. The electrostatic lens may further include a second terminal electrode, a second suppression electrode, and a second ground electrode disposed along a second side of the ion beam line. The second ground electrode is grounded and is disposed adjacent to the outlet. The second suppression electrode is disposed further downstream along the ion beam line than the first suppression electrode. The implantation system may further include a power supply operable to supply voltage and current to the electrostatic lens to control the ion beam.

[0007]

[0007] In another approach, the lens can include a chamber having an inlet for receiving an ion beam and an outlet for directing the ion beam toward a target, a first terminal electrode, a first suppression electrode, and a first ground electrode disposed along a first side of the ion beam line. The first ground electrode is grounded and is disposed adjacent to the outlet. The lens may further include a second terminal electrode, a second suppression electrode, and a second ground electrode disposed along a second side of the ion beam line. The second ground electrode is grounded and is disposed adjacent to the outlet.

[0008]

[0008] In another approach, the method can include providing an electrostatic lens that includes an inlet for receiving an ion beam and an outlet for directing the ion beam toward a target, the electrostatic lens including a first terminal electrode, a first suppression electrode, and a first ground electrode disposed along a first side of the ion beam line, the first ground electrode being grounded and disposed adjacent to the outlet. The electrostatic lens may further include a second terminal electrode, a second suppression electrode, and a second ground electrode disposed along a second side of the ion beam line, the second ground electrode being grounded and disposed adjacent to the outlet. The method may further include supplying a voltage and a current to the electrostatic lens to control the ion beam.

[0009]

[0009] The accompanying drawings illustrate exemplary approaches of the present disclosure that have been devised heretofore for the practical application of the principles of the present disclosure.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0011]

[0013] The drawings are not necessarily to scale. The drawings are merely representations and are not intended to depict specific parameters of the present disclosure. The drawings are intended to illustrate exemplary embodiments of the present disclosure and should not be regarded as limiting its scope. In the drawings, elements with the same numbers represent the same elements.

[0012]

[0014] The following will describe in more detail the ion implantation system, electrostatic filter or lens, and method according to the present disclosure, with reference to the accompanying drawings in which embodiments of the present disclosure are shown. These ion implantation systems, electrostatic filters, and methods can be embodied in many different forms and should not be construed as limited to the embodiments described herein. Instead, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the systems and methods to those skilled in the art.

[0013]

[0015] An approach for reducing particles within an ion implantation apparatus is provided herein. The electrostatic filter can include a housing and a plurality of conductive beam optical components (e.g., electrodes) within the housing. The conductive beam optical components are disposed around an ion beam line directed toward a wafer and can include an inlet or terminal electrode proximate to an inlet of the housing. The conductive beam optical components can further include a suppression electrode downstream along the ion beam line from the terminal electrode, a powered electrode downstream of the suppression electrode, and a ground electrode downstream of the powered electrode. In some embodiments, the electrodes below the ion beam are farther from the ion beam line than the electrodes above the ion beam, and thus the suppression and powered electrodes disposed below are physically blocked or shielded so as not to be coated by the backspatter material coming back from the wafer. Further, in some embodiments, the suppression electrode disposed below can be disposed further downstream along the ion beam line than the suppression electrode disposed above. The electrostatic filter can further include an electrical system for supplying voltage and current to each of the conductive beam optical components.

[0014]

[0016] Referring now to FIG. 1, an exemplary system according to the present disclosure is shown. An ion implantation system (hereinafter, "system") 10 represents a process chamber that houses an ion source 14 for generating an ion beam 18, an ion implantation device, and a series of beam line components 16, etc. The ion source 14 can include a chamber for receiving a gas flow 24 and generating ions therein. The ion source 14 can also include a power supply and an extraction electrode assembly disposed in the vicinity of the chamber. The beam line components 16 can include, for example, a mass analyzer 34, a first acceleration / deceleration stage 36, a collimator 38, and an electrostatic lens or electrostatic filter (EF) 40 that can correspond to the acceleration / deceleration stage. Although not shown, the beam line components 16 may further include a plasma flood gun (PFG) downstream of the EF 40.

[0015]

[0017] In an exemplary embodiment, the beam line components 16 can filter, focus, and manipulate the ions or ion beam 18 to have a desired species, shape, energy, and other qualities. The ion beam 18 passing through the beam line components 16 can be directed towards a substrate mounted on a platen or clamp within the process chamber 46. As will be appreciated, the substrate can be moved in one or more dimensions (e.g., translated, rotated, and tilted).

[0016]

[0018] As shown, there may be one or more sources 28 operable with the chamber of the ion source 14. In some embodiments, the materials provided from the source 28 can include source materials and / or additional materials. The source materials can include dopant species introduced onto the substrate in the form of ions. On the other hand, the additional materials may include diluents introduced into the ion source chamber of the ion source 14 together with the source materials to dilute the concentration of the source materials within the chamber of the ion source 14. Also, the additional materials may include cleaning agents (e.g., etchant gases) introduced into the chamber of the ion source 14 and transported within the system 10 to clean one or more of the beamline components 16.

[0017]

[0019] In various embodiments, different species can be used as source and / or additional materials. Examples of source and / or additional materials can include atomic or molecular species including boron (B), carbon (C), oxygen (O), germanium (Ge), phosphorus (P), arsenic (As), silicon (Si), helium (He), neon (Ne), argon (Ar), krypton (Kr), nitrogen (N), hydrogen (H), fluorine (F), and chlorine (Cl). The species listed above are non-limiting, and it will be recognized by those skilled in the art that other atomic or molecular species can also be used. Depending on the application, these species can be used as dopants or additional materials. Specifically, one species used as a dopant in one application may be used as an additional material in another application, or vice versa.

[0018]

[0020] In an exemplary embodiment, the source and / or additional materials are provided into the ion source chamber of the ion source 14 in the form of a gas or vapor. If the source and / or additional materials are in a non-gaseous or non-vapor form, a vaporizer (not shown) may be provided near the source 28 to convert the materials into a gaseous or vapor form. A flow controller 30 may be provided to control the amount and rate at which the source and / or additional materials are supplied to the system 10.

[0019]

[0021] EF40 can be configured to independently control the deflection, acceleration, deceleration, and focusing of the ion beam 18. In one embodiment, EF40 is a vertical electrostatic energy filter (VEEF). As will be described in more detail below, EPM40 can include an electrode configuration including a set of upper electrodes disposed above the ion beam 18 and a set of lower electrodes disposed below the ion beam 18. The set of upper electrodes and the set of lower electrodes are stationary and can be fixed in position. To independently control the deflection, acceleration, deceleration, and / or focusing of the ion beam 18, the potential difference between the set of upper electrodes and the set of lower electrodes may vary along the central ion beam trajectory so as to reflect the energy of the ion beam 18 at each point along the central ion beam trajectory.

[0020]

[0022] Without limitation, the ion source 14 can include a generator, a plasma exciter, a plasma chamber, and the plasma itself. The plasma source can be an inductively coupled plasma (ICP) source, a toroidally coupled plasma source (TCP), a capacitively coupled plasma (CCP) source, a helicon source, an electron cyclotron resonance (ECR) source, an indirectly heated cathode (IHC) source, a glow discharge source, an electron beam generated ion source, or other plasma sources known to those skilled in the art.

[0021]

[0023] The ion source 14 can generate an ion beam 18 for processing a substrate. In various embodiments, the cross-section of the ion beam can have a target shape such as a spot beam or a ribbon beam as known in the art. To process the substrate, the ion beam 18 can be accelerated or decelerated to acquire a target energy by establishing a voltage (potential) difference between the ion source 14 and the wafer.

[0022]

[0024] Next, referring to FIG. 2, EF40 according to an exemplary embodiment will be described in more detail. As shown, EF40 includes an EF chamber 50 defined by a chamber housing 52. EF40 can further operate with one or more vacuum pumps (not shown) for adjusting the pressure in the EF chamber 50. EF40 is bordered along one end by a PFG32 having an opening 37, enabling the ion beam 18 to reach the wafer 35 through the opening. As shown, PFG32 is between EF40 and the wafer 35, and PFG32 and the wafer 35 are oriented at an angle β with respect to the ion beam line / trajectory 72. By way of non-limiting example, the angle β may be between 5 and 30°. Due to the arrangement of the plurality of conductive beam optical components 70A - 70J within the EF chamber 50, as well as the orientation of EF40 with respect to PFG32 and the wafer 35, EF40 is considered to be "curved" or asymmetric.

[0023]

[0025] As shown, EF40 can include one or more conductive beam optical components 70A - 70J, which can be a plurality of graphite electrode rods arranged along the ion beam line / trajectory 72. In this embodiment, the conductive beam optical components 70A - 70J are arranged in an asymmetric configuration with respect to the ion beam line / trajectory 72. By way of non-limiting example, the plurality of conductive beam optical components 70A - 70J may include a set of inlet or terminal electrodes 70A, 70B proximate to the inlet 75 of EF40 and a set of outlet or ground electrodes 70I, 70J proximate to the outlet 76 of EF40. In some embodiments, the terminal electrodes 70A, 70B are maintained at a terminal voltage and the ground electrodes 70I, 70J are grounded.

[0024]

[0026] As further shown, EF40 can include a set of suppression electrodes 70C and 70D disposed along both sides of the ion beam line 72 downstream of the terminal electrodes 70A and 70B, and a plurality of power electrodes 70E to 70H between the suppression electrodes 70C and 70D and the ground electrodes 70I and 70J. In some embodiments, the voltages of the suppression electrodes 70C and 70D are less than or equal to the terminal voltages of the terminal electrodes 70A to 70B. Without limitation, when the ion beam 18 is a decelerated ion beam, the power electrodes 70E and 70G can be more positive than the suppression electrode 70C, and similarly, the power electrodes 70F and 70H can be more positive than the suppression electrode 70D. When the ion beam 18 is an accelerated ion beam, the power electrodes 70E and 70G can be more negative than the suppression electrode 70C, and the power electrodes 70F and 70H can be more negative than the suppression electrode 70D.

[0025]

[0027] As shown, each set of electrode pairs provides a space / aperture through which the ion beam 18 (e.g., a ribbon beam) can pass. Without limitation, the first distance "D1" between the suppression electrode 70C and the ion beam line 72 may be smaller than the second distance "D2" between the suppression electrode 70D and the ion beam line 72. Further, in some embodiments, the suppression electrode 70D may be disposed further downstream along the ion beam line than the suppression electrode 70C. In other words, the distance "D3" between the suppression electrode 70C and the ground electrode 70I is greater than the distance "D4" between the suppression electrode 70D and the ground electrode 70J.

[0026]

[0028] In an exemplary embodiment, the conductive beam optical components 70A - 70J include pairs of conductive pieces electrically coupled to each other. Alternatively, the conductive beam optical components 70A - 70J may be a continuous unit structure each including an opening for an ion beam to pass through. In the illustrated embodiment, the upper and lower portions of each electrode pair may be at different potentials (e.g., in separate conductive pieces) to deflect the ion beam passing therethrough. The conductive beam optical components 70A - 70J are depicted as five electrode pairs, but a different number of elements (or electrodes) may be utilized. For example, the configuration of the conductive beam optical components 70A - 70J can utilize an electrode set in the range of 3 - 10.

[0027]

[0029] In some embodiments, the ion beam 18 passing through the electrodes along the ion beam line 72 may contain boron or other elements. The electrostatic focusing of the ion beam can be achieved by controlling the potential steps along the ion beam line 72 using several thin electrodes (e.g., suppression / focusing electrodes 70C, 70D). In the configuration of the illustrated conductive beam optical components 70A - 70J, the ion beam 18 can be decelerated and deflected by the powerward electrodes 70E - 70G.

[0028]

[0030] In some embodiments, a power supply 78 (e.g., a DC power supply) supplies voltage and current to EF40. The voltage / current can be supplied to the conductive beam optical components 70A - 70J to generate plasma within the EF chamber 50. In various embodiments, the voltage and current provided by the power supply 78 may be constant or variable. In one embodiment, the conductive beam optical components 70A - 70J are held at a series of DC potentials from 0.1 keV to 100 keV. The conductive beam optical components 70A - 70J may be electrically driven in parallel (e.g., individually) or in series to enable uniform and / or independent operation of each of the conductive beam optical components 70A - 70J.

[0029]

[0031] In some embodiments, as further shown, the terminal electrode 70B, the suppression electrode 70D, and the power supply electrodes 70F, 70H are shielded under the line of sight 67 by the ground electrode 70J so that the sputtering material from the wafer 35 does not deposit, and these electrodes below the line of sight 67 can be kept clean. As shown in the figure, the line of sight 67 may be defined by the inner surface 68 of the ground electrode 70J. With such a configuration, the source of particles that may potentially be generated at the electrodes 70B, 70D, 70F, 70H disposed below is eliminated or at least reduced, and the transport mechanism of the peeled-off material to the electrodes 70A, 70C, 70E, 70G disposed above is eliminated or at least reduced.

[0030]

[0032] Next, turning to FIG. 3, a method 100 according to an embodiment of the present disclosure will be described. In block 101, the method 100 can include providing an electrostatic lens that includes an inlet for receiving an ion beam and an outlet for directing the ion beam toward a target. The electrostatic lens may include a first terminal electrode, a first suppression electrode, and a first ground electrode disposed along a first side of the ion beam line, and the first ground electrode is grounded and disposed adjacent to the outlet. The electrostatic lens may further include a second terminal electrode, a second suppression electrode, and a second ground electrode disposed along a second side of the ion beam line, and the second ground electrode is grounded and disposed adjacent to the outlet.

[0031]

[0033] In some embodiments, the first terminal electrode and the second terminal electrode may be maintained at a terminal voltage. In some embodiments, the voltages of the first and second suppression electrodes may be maintained at a level less than or equal to the terminal voltage. In some embodiments, the first suppression electrode may be disposed at a first distance from the first ground electrode, and the second suppression electrode may be disposed at a second distance from the second ground electrode, and the second distance is less than the first distance.

[0032]

[0034] In block 103, method 100 can include supplying a voltage and a current to an electrostatic lens to control an ion beam. In some embodiments, the voltage and the current may be supplied to a first set of powered electrodes along a first side of the ion beam line and a second set of powered electrodes along a second side of the ion beam line, and the first set of powered electrodes and the second set of powered electrodes are operable to decelerate and deflect an ion beam traveling through the electrostatic lens toward the wafer.

[0033]

[0035] As used herein, for convenience and clarity, terms such as "above," "below," "upper," "lower," "vertical," "horizontal," "lateral," "longitudinal," etc. are used to describe the geometric shape and orientation of the components of a semiconductor manufacturing apparatus as they appear in the figures, and the relative arrangement and orientation of these components and their parts. The terms include the specifically recited words, their derivatives, and words having similar meanings.

[0034]

[0036] As used herein, an element or act described in the singular and beginning with the word "a" or "an" is understood to potentially include a plurality of elements or acts. Further, reference to "one embodiment" of the present disclosure is not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0035]

[0037] According to embodiments of the present disclosure, the terms "more positive" or "less positive," "greater" or "less" used herein with respect to voltage (potential) may refer to the relative voltage of two different objects. Thus, for example, 0 V is "greater" or "more positive" than -5 kV, and +10 kV is "greater" or "more positive" than 0 V. Further, -10 kV is "less positive" than -5 kV. The terms "less negative" or "more negative" may also refer to relative voltage. For example, it can be said that 0 kV is more negative than +5 kV, while +10 kV is less negative than +5 kV.

[0036]

[0038] From the above, this embodiment advantageously eliminates indirect substrate contamination caused by the material re-sputtered from the substrate accumulating on the electrodes of the electrostatic filter and becoming an additional source of contamination due to subsequent sputtering or peeling from the electrodes.

[0037]

[0039] In this specification, specific embodiments of the present disclosure have been described. However, the present disclosure is not limited thereto, and the present disclosure has a scope as broad as permitted by the art and as long as the specification can be read in the same manner. Therefore, the above description should not be construed in a limiting sense. Those skilled in the art will envision other modifications within the scope of the claims appended hereto and the spirit thereof.

Claims

1. An ion implantation system, comprising an electrostatic lens including an inlet for receiving an ion beam and an outlet for directing the ion beam toward a target, and a power supply operable to supply a voltage and a current to the electrostatic lens to control the ion beam wherein the electrostatic lens comprises a first terminal electrode, a first suppression electrode, and a first ground electrode disposed along a first side of the ion beam line and grounded and adjacent to the outlet, and a second terminal electrode, a second suppression electrode, and a second ground electrode disposed along a second side of the ion beam line and grounded and adjacent to the outlet, and a first distance between the first suppression electrode and the ion beam line is less than a second distance between the second suppression electrode and the ion beam line, a third distance between the first ground electrode and the ion beam line is greater than a fourth distance between the second ground electrode and the ion beam line, the second suppression electrode is disposed below a line of sight extending between the inlet and the target, and the line of sight is defined by an inner surface of the second ground electrode, the ion implantation system.

2. The ion implantation system according to claim 1, wherein the second suppression electrode is disposed further downstream along the ion beam line than the first suppression electrode.

3. further comprising a first set of power supply electrodes along the first side of the ion beam line and a second set of power supply electrodes along the second side of the ion beam line, the first set of power supply electrodes and the second set of power supply electrodes being operable to decelerate and deflect the ion beam, the ion implantation system according to claim 1.

4. The ion implantation system according to claim 1, wherein the voltage of the first terminal electrode and the voltage of the second terminal electrode are maintained at the same voltage.

5. The ion implantation system according to claim 4, wherein the voltage of the first suppression electrode and the voltage of the second suppression electrode are smaller than the voltages of the first terminal electrode and the second terminal electrode, or equal to the voltages of the first terminal electrode and the second terminal electrode.

6. The ion implantation system according to claim 1, further comprising a plasma flood gun disposed between the electrostatic lens and the wafer, wherein the plasma flood gun and the wafer are oriented at an angle with respect to the electrostatic lens.

7. The ion implantation system according to claim 1, wherein a first distance between the first suppression electrode and the first ground electrode is greater than a second distance between the second suppression electrode and the second ground electrode.

8. A method comprising: providing an electrostatic lens including an inlet for receiving an ion beam and an outlet for directing the ion beam towards a target; supplying a voltage and a current to the electrostatic lens to control the ion beam; wherein the electrostatic lens comprises: a first terminal electrode, a first suppression electrode, and a first ground electrode grounded and disposed adjacent to the outlet, disposed along a first side of the ion beam line; and a second terminal electrode, a second suppression electrode, and a second ground electrode grounded and disposed adjacent to the outlet, disposed along a second side of the ion beam line. The method comprises: The first distance between the first suppression electrode and the ion beam line is smaller than the second distance between the second suppression electrode and the ion beam line, the third distance between the first ground electrode and the ion beam line is larger than the fourth distance between the second ground electrode and the ion beam line, and the second suppression electrode is disposed below a line of sight extending between the inlet and the target, the line of sight being defined by an inner surface of the second ground electrode, a method.

9. Further comprising supplying the voltage and the current to a first set of powered electrodes along the first side of the ion beam line and a second set of powered electrodes along the second side of the ion beam line, the first set of powered electrodes and the second set of powered electrodes being operable to decelerate and deflect the ion beam, the method according to claim 8.

10. Further comprising maintaining the voltage of the first terminal electrode and the voltage of the second terminal electrode at the same voltage, the method according to claim 8.

11. Further comprising maintaining the voltage of the first suppression electrode and the voltage of the second suppression electrode at a level less than or equal to the voltage of the first terminal electrode and the voltage of the second terminal electrode, the method according to claim 10.

12. Disposing the first suppression electrode at a first distance from the first ground electrode; Disposing the second suppression electrode at a second distance from the second ground electrode; Further comprising, the second distance being smaller than the first distance, the method according to claim 8.

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