Apparatus and method for beam processing of a substrate

Abstract

To provide a device and a method for substrate beam processing.SOLUTION: A substrate processing system includes: a processing chamber; a substrate holder configured to hold the substrate and rotate the substrate around an axis perpendicular to a working surface of the substrate; an electron emitter which is adapted to emit a first electron beam guided to a first surface in a peripheral region of the substrate, and in which the first electron beam includes first beam energy and a first beam current sufficient to volatilize the material from the first surface in the peripheral region of the substrate; an air flow system configured to guide the flow of gas over the working surface of the substrate; and an exhaust system configured to recover the gas containing the volatilized material from the peripheral region.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 914,160, filed Oct. 11, 2019, entitled “Removal of Edge Beads Using an Electron Beam.” This application is incorporated herein by reference.

[0002] The present invention generally relates to substrate processing methods, and in certain embodiments, to apparatus and methods for beam processing of substrates.

Background Art

[0003] Typically, the manufacture of semiconductor devices involves many processes that are used to form various features of the semiconductor device and multiple levels or layers on the upper surface of a substrate such as a semiconductor wafer. For example, lithography is a process that typically includes the step of transferring a predetermined circuit pattern onto a photoresist layer formed on the upper surface of a substrate. During the lithography process, an amount of liquid photoresist solution is dispensed near the center of the substrate, the resist solution is distributed across the upper surface of the substrate using a spin coating process, the photoresist is exposed to radiation through a predetermined pattern, and then the pattern is developed, whereby a photoresist layer is formed on the upper surface. Thereby, a topographic pattern is formed.

[0004] Spin coating of the photoresist is performed in an automated track system using substrate handling equipment that transports the substrate between various lithography operation stations (e.g., a photoresist spin coating station, a development station, a heating station, and a cooling station, etc.). The automated substrate track can perform various processing operations simultaneously. One family of industrially widely used automated track systems is the line of coater / developer tracks commercially available from vendors such as Tokyo Electron Limited.

[0005] During the spin coating process, the substrate is held by a substrate holder (which is, for example, a disk-shaped rotating spin chuck). The diameter of the substrate holder is smaller than the diameter of the substrate. The substrate holder is arranged such that the main surface of the substrate is oriented in a level horizontal plane. During operation, the substrate holder supports the back surface of the substrate, applies a suction force to the back surface of the substrate, and holds the substrate in a predetermined position during rotation of the substrate holder. The amount of the liquid photoresist solution is placed at the center of the upper surface of the substrate. The substrate holder rotates the substrate at a high rotational speed, and due to the centrifugal force, the liquid photoresist solution spreads radially outward from the center of the substrate toward the peripheral edge of the substrate, and the upper surface of the substrate is coated.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] FIG. 1A shows a partial cross-sectional view of a conventional substrate holder 105 having a substrate 110. As shown in FIG. 1A, the back surface of the substrate 110 is supported by the substrate holder 105, which can also rotate the substrate 110. The peripheral region 115 of the substrate 110 is highlighted, which exists throughout the periphery of the substrate 110.

[0007] FIG. 1B shows a partial cross-sectional view of a conventional substrate holder 105 having a substrate 110. The photoresist layer 130 formed on the upper surface of the substrate 110 is highlighted. The photoresist layer 130 spin-coated on the upper surface of the substrate 110 has an end bead 135 formed as an aggregate of excess liquid photoresist solution along the peripheral region 115 of the substrate 110.

[0008] Ideally, excess liquid photoresist solution is discharged from the periphery of the wafer. However, in practice, some excess liquid photoresist solution accumulates along the periphery of the substrate as a result of, for example, the influence of the spin coating process due to surface tension. The liquid photoresist solution accumulates on the upper surface, back surface, edges, or a combination thereof of the substrate. The accumulated liquid photoresist solution forms edge beads when the photoresist solution solidifies. Subsequently, a portion of the edge beads becomes small pieces and peels off from the wafer, which may cause particulate contamination during subsequent process steps. Unfortunately, particulate contamination can affect the yield loss of the integrated circuits formed on the wafer.

[0009] FIG. 2A shows a partial cross-sectional view of a conventional substrate processing system 200. Conventional chemical edge bead removal techniques for removing edge beads of the substrate are highlighted.

[0010] As shown in FIG. 2A, the substrate processing system 200 has a substrate holder 105 having a supported substrate 110. The substrate 110 has a photoresist layer 130 formed on its working surface. Edge beads 135 are present in the peripheral region of the substrate 110. The solvent dispenser 205 distributes a solvent 210 onto the substrate 110, and the solvent 210 softens the edge beads 135 and promotes the removal of the edge beads 135. The solvent dispenser 205 distributes the solvent 210, and the substrate holder 105 rotates the substrate 110. The problem with chemical edge bead removal is that chemical edge bead removal typically needs to be performed within a short time after the photoresist layer 130 is formed and before the liquid photoresist material is completely cured.

[0011] FIG. 2B shows a partial cross-sectional view of a conventional substrate processing system 250. Conventional wafer edge exposure technology (WEE) for removing edge beads of the substrate is highlighted.

[0012] As shown in FIG. 2B, the substrate processing system 250 includes a substrate holder 105 having a supported substrate 110. The substrate 110 has a photoresist layer 130 formed on its working surface. End beads 135 are present in the peripheral region of the substrate 110. Through a mask 265, a light source 255 emits light 260 (such as ultraviolet light, wide-band light, etc.), and the end beads 135 are exposed without exposing the remaining portion of the photoresist layer 130. When the light source 255 emits light 260, the substrate holder 105 rotates the substrate 110. The problem of WEE is that WEE is only effective for photoresist materials and is usually substantially non-reactive to light typically used for WEE, and has no effect on other materials such as ARC and polyimide. Therefore, it is difficult to use WEE to remove these materials from the end beads.

Means for Solving the Problem

[0013] In one embodiment of the present invention, a substrate processing system is provided. The substrate processing system includes a processing chamber, a substrate holder disposed in the processing chamber, the substrate holder being configured to hold a substrate and rotate the substrate around an axis perpendicular to the working surface of the substrate, an electron emitter adapted to emit a first electron beam induced on a first surface of the peripheral region of the substrate, the first electron beam having a first beam energy and a first beam current sufficient to volatilize material from the first surface of the peripheral region of the substrate, an air flow system configured to induce a gas flow across the working surface of the substrate, and an exhaust system configured to collect the gas containing the material volatilized from the peripheral region.

[0014] In another embodiment, a method of processing a substrate is provided. The method is a method of processing a substrate, comprising the steps of: receiving the substrate in a substrate holder of a processing chamber; rotating the substrate about an axis perpendicular to the working surface of the substrate; turning on an air flow system to induce a gas flow across the working surface of the substrate; and exposing a peripheral region of the substrate to a first electron beam to volatilize material from the peripheral region of the substrate.

[0015] In yet another embodiment of the present invention, a method of processing a substrate is provided. The method comprises the steps of: receiving the substrate; flowing a gas across the working surface of the substrate, wherein the gas flows at a specific flow rate; while rotating the substrate about an axis perpendicular to the working surface of the substrate, exposing a peripheral region of the substrate to an electron beam from an electron emitter to volatilize a portion of the material in the peripheral region; and checking that a stop threshold is met and, based thereon, turning off the electron emitter. A method is provided that has these steps.

[0016] For a more complete understanding of the present invention and its advantages, reference is made to the following detailed description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0017]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8A

Figure 8B

Figure 9

Mode for Carrying Out the Invention

[0018] Unless otherwise noted, corresponding reference numerals and numbers generally represent corresponding parts in different figures. The drawings are described to clearly show relevant aspects of the embodiments, and the scale is not necessarily described. In the figures, the ends of the features do not necessarily represent the peripheral edges of the scope of the features.

[0019] Hereinafter, the fabrication and use of various embodiments will be described in detail. However, it should be understood that the various embodiments described in this application are widely applicable in specific situations. The specific embodiments disclosed are merely examples of specific ways of fabricating and using the various embodiments and should not be construed as limiting the scope.

[0020] The various techniques described in the present application relate to removing material along a peripheral region of a substrate using an electron beam. In one example, when the substrate is rotated by a substrate holder, an end bead containing a material such as a metal-containing photoresist material is removed along the peripheral region of the substrate by exposing the peripheral region of the substrate to an electron beam. The electron beam exposed to the electron beam based on the material to be removed or measurement data volatilizes the metal-containing photoresist material. The electron beam exposure is characterized by, for example, beam energy, beam current, beam size, and time. The rotating substrate is prevented by the electron beam from overheating and being damaged at any particular portion of the substrate, and further provides an accuracy that cannot be normally achieved by the movement of the electron beam along the peripheral region of the fixed substrate.

[0021] By spin coating, some materials such as photoresist, anti-reflection coating (ARC), polyimide coating, etc. are placed on the working surface of the substrate. Spin coating is a process in which a material in a liquid state is placed at the center of the working surface of the substrate, the substrate is rotated rapidly, and the material is dispersed in a thin film state over the working surface of the substrate. After spin coating, curing by heating is performed, or the material is thermally cured. In addition to the formation of a thin film over the working surface of the substrate, an end bead is formed in the peripheral region of the substrate in the spin coating process, which can lead to major problems during substrate processing. The end bead is formed by the surface tension of the material in a fluid state.

[0022] The edge bead may be formed, for example, on the upper surface of the substrate (usually referred to as the working surface of the substrate), the bottom surface of the substrate (usually referred to as the back surface of the substrate), the edge of the substrate, or a combination thereof. A common problem with edge beads is that during substrate handling (such as when the substrate is gripped by a transfer robot or moved between substrate processing stations), the edge bead material flakes off in pieces and deposits on the working surface of the substrate (which becomes contaminants and reduces yield), or on the surface of the processing equipment (such as the surface of the substrate holder. This leads to a decrease in contact between the substrate and the substrate holder, which can result in a significant decrease in yield due to substrate misalignment during subsequent process steps). Therefore, it is necessary to remove the edge bead.

[0023] In one embodiment, the material removal system uses an electron beam to remove material from the peripheral region of the substrate. The material removal system has an electron emitter, which forms an electron beam oriented to the peripheral region of the substrate. The electron beam may be used to remove material from the peripheral region of the working surface of the substrate, the back surface of the substrate, the edge of the substrate, or a combination of the working surface, back surface, and edge of the substrate. The material to be removed may include the peripheral region of the spin-coated film and the edge bead formed in part. Materials that may be included, but are not limited to, spin-coated photoresist (such as metal-containing photoresist, long-chain polymer photoresist, etc.), ARC, polyimide, etc. are heated and then vaporized by exposure to the electron beam.

[0024] The advantage of the electron beam is that it is not affected by surface reflection. Surface reflection is a problem with laser beams and highly reflective materials. For example, metal-containing photoresist is reflective to laser beams and light beams, but is usually not reflective to electron beams.

[0025] In the remaining discussion, focus is placed on the use of an electron beam, an electron source, and an electron beam for removing material on a substrate. However, other types of beams, such as an ion beam containing volatile or inert atoms (such as argon, hydrogen, etc.), can also be used for removing material on a substrate. Therefore, the arguments regarding the electron beam should not be construed as being limited within the scope of one embodiment.

[0026] In certain embodiments, the metal removal system has an exhaust system or a vacuum system for removing the volatilized material, and the volatilized material is prevented from depositing on the substrate or on the substrate processing tool. If the volatilized material returns to the substrate, the volatilized material contaminates the substrate and leads to a reduction in yield. When the volatilized material is deposited on the substrate processing tool, the volatilized material may prevent the substrate from being properly positioned on the substrate processing tool, and substrate distortion and misalignment may occur.

[0027] In certain embodiments, the substrate is rotated at a specific speed (e.g., RPM or angular velocity). Rotation of the substrate with the electron beam fixed is more accurate than moving the electron beam around the peripheral region of the fixed substrate (by physically moving the electron emitter or deflecting the electron beam using, for example, a magnetic field or an electric field). The substrate may be rotated, for example, by a substrate holder. For example, a substrate holder used for spin coating the substrate may be used for rotating the substrate for the material removal process. In another example, the substrate may be rotated for material removal using a substrate holder of a substrate processing tool specially designed for material removal. Rotation of the substrate may be facilitated such that the exposure of the electron beam incident on the substrate by the electron beam is relatively uniform. Also, rotation of the substrate may be facilitated such that the electron beam does not incident on any specific portion of the substrate for a long time. This may cause a part of the substrate to overheat and damage the substrate.

[0028] In one embodiment, the removal of material in the peripheral region of the substrate occurs immediately after spin-coating the material onto the substrate. By removing the material immediately after the spin-coating step, more rapid removal of the spin-coated material is facilitated. This is because the spin-coated material has not been thermally cured and the spin-coated material has not been heated. Also, by removing the material immediately after the spin-coating step, the same processing tool used in the spin-coating step (by adding an electron emitter and optionally an exhaust system) can be utilized, eliminating the need to move the substrate to another material removal station.

[0029] In one embodiment, the removal of material in the peripheral region of the substrate occurs after spin-coating the material onto the substrate, and the removal of the material occurs within a processing tool different from the processing tool used for spin-coating the material onto the substrate. Removal of the material in another processing tool enables optimization of the processing tool for material removal and can improve overall efficiency.

[0030] In one embodiment, the removal of material in the peripheral region of the substrate occurs after heating the substrate to thermally cure or cure the spin-coated material. Removal of the material after heat-treating the spin-coating material is performed within a dedicated material removal station, eliminating the need to modify the existing heat-treatment station. Alternatively, removal of the material after heating the spin-coated material may be performed within the station used for heating the substrate (by adding an electron emitter, an exhaust system, and a rotating substrate holder), in which case the need to move the substrate to another material removal station is eliminated.

[0031] In one embodiment, the removal of material in the peripheral region of the substrate occurs before heating the substrate to thermally cure or cure the spin-coated material. Removal of the material before heat-treating the spin-coating material simplifies the material removal process. This is because the material has not yet been thermally cured or cured. If thermally cured or cured, removal of the material can become more difficult.

[0032] FIG. 3 shows an isometric view of a portion of a material removal system 300 according to one embodiment of the present disclosure. The material removal system 300 has a substrate 110 on a substrate holder (not shown in FIG. 3), and the substrate holder is configured to rotate the substrate 110 at a specific speed. The substrate 110 has a peripheral region 115, and the peripheral region 115 includes an end bead of the spin-coated material removed by the material removal system 300. The material removal system 300 also has an electron emitter 305, which is configured to emit an electron beam 310 with a specific electron energy and a specific current. The electron beam 310 is incident on the spin-coated material in the peripheral region 115 of the substrate 110, heats the spin-coated material, and volatilizes the spin-coated material. The volatilized material is indicated by the dashed line 315 in FIG. 3. A part of the peripheral region 115 indicated by the white region 320 represents the portion of the substrate 110 from which the spin-coated material has been removed.

[0033] In FIG. 3, the electron emitter 305 is shown oriented toward the working surface of the substrate 110, but the electron emitter 305 may be moved to a new position such that the electron beam 310 is oriented toward the back surface of the substrate 110 or the end of the substrate 110. Alternatively, the material removal system 300 may have two or more electron emitters. For example, a first electron emitter may be oriented like the electron emitter 305 shown in FIG. 3, and a second electron emitter may be oriented such that the electron beam generated by the second electron emitter is oriented toward the back surface of the substrate 110. In such an example, a third electron emitter may be oriented such that the electron beam generated by the third electron beam is oriented toward the end of the substrate 110.

[0034] In another alternative example, a single electron emitter emits a first electron beam having sufficient beam energy and current to volatilize the end bead on the working surface of the substrate 110, and emits a second electron beam having sufficient electron beam energy and current to volatilize the end bead on the back surface of the substrate 110. The second electron beam does not substantially heat the substrate 110 and has sufficient electron beam energy for electrons to pass through the substrate 110, thereby suppressing damage to the substrate 110. The electrons of the second electron beam have high beam energy and they pass through the electron cloud of the atoms of the substrate 110 without interaction (or with only slight interaction), so the substrate 110 is not heated up to the damage point of the substrate 110. However, when the second electron beam passes through the substrate 110, the energy of the second electron beam is attenuated to a sufficient level to be able to sufficiently volatilize the end bead present on the back surface of the substrate 110. In other words, when the beam energy of the second electron beam decreases (for example, to a level substantially equal to the beam energy of the first electron beam), the electrons of the second electron beam interact more with the electron cloud of the atoms of the material of the end bead, and the material is volatilized. Therefore, the drawings and descriptions of a single electron emitter that generates an electron beam oriented towards the working surface of the substrate should not be construed as limiting the scope of one embodiment.

[0035] In one embodiment, the electron beam has a sufficiently wide beam width and material is removed from the peripheral region of the working surface and at least a part of the end of the substrate.

[0036] In one embodiment, the electron emitter is oriented such that the electron beam is perpendicular to the working surface of the substrate. For an electron beam perpendicular to the working surface of the substrate, the efficiency of the electron beam can be maximized.

[0037] In one embodiment, the electron beam used for material volatilization is characterized by the physical scale of the electron beam. The physical scale of the electron beam includes the energy of the electrons in the electron beam and the number of electrons in the electron beam.

[0038] For example, an electron beam is characterized by the beam energy of the electron beam and the beam flux or beam current. The beam energy is an indicator of the amount of energy of the electrons in the electron beam and determines the ability of the electrons to penetrate the material. The penetration amount increases with an increase in the beam energy. A relatively low beam energy that can sufficiently penetrate the material to be removed but does not enter deep into the substrate needs to be selected. A beam with a high beam energy can penetrate the material without substantially heating the material. This is because the electrons pass through the electron clouds of individual atoms without interacting. Once the beam energy of the beam drops to the point where the interaction between the electrons and the electron clouds of the individual atoms of the material begins, the material is heated to the vaporization point.

[0039] In situations where a low beam energy cannot be generated, physical techniques are used to reduce the beam energy. For example, the beam energy may be reduced by passing the electron beam through a metal foil.

[0040] The beam current (or beam flux) determines the temperature rise of the material. With a relatively low beam current, a local temperature rise occurs, which may be significant. For example, with a local temperature rise, only the surrounding area of the substrate can be heated, and the remaining bulk portion of the substrate can remain unaffected. The heating of the substrate may be configured such that sufficient heat is provided to the surface of the substrate to volatilize the material. In another example, the electron beam is characterized by the beam size. For example, with a narrow beam size, more rapid volatilization of the material to be removed may be possible compared to a wide beam size because a small amount of material is exposed to the electron beam.

[0041] Also, in certain embodiments, the characteristics of the electron beam include the beam type of the electron beam. For example, the beam type may be continuous or pulsed. For example, the electron beam is a continuous beam of electrons. In a continuous beam of electrons, a certain amount of heating is provided to the material to be removed. In another example, the electron beam is a pulsed beam of electrons. The electron beam is a pulsed beam having a specific pulse width and duty cycle. The pulsed electron beam suppresses the ionization of the gas flowing above the substrate, which can enhance the function of the electrons that volatilize the material to be removed. Also, pulsed operation can help suppress heat accumulation in the substrate (due to heat conduction). This is because the heated material can be cooled during the pulses.

[0042] Also, in certain embodiments, the electron beam is characterized by electron beam exposure (or equivalent to electron beam dosage). Here, electron beam exposure is an indicator of the amount of time that a specific portion of the material is exposed to the electron beam. The stopping threshold used to determine when to stop the material removal process may be determined using electron beam exposure. Electron beam exposure may be a function of the time during which the electron emitter emits electrons. In other words, electron beam exposure is a function of how long the electron beam is on. Also, electron beam exposure may be a function of the rotation speed of the substrate. For example, when the rotation speed of the substrate is low (low RPM, or low angular velocity), each part of the substrate is exposed to the electron beam for a longer time interval compared to when the rotation speed of the substrate is high. Therefore, the electron beam exposure is high. On the other hand, when the substrate is rotated at a high speed (high RPM, or high angular velocity), each part of the substrate is exposed to the electron beam for a shorter time. However, when the substrate is rotated at a high speed and the electron beam is on for a long time, the effective electron beam exposure is large. This is because even though each exposure is short due to the high rotation speed, the on-time of the electron beam is long, so each part of the substrate is exposed to the electron beam for a longer time.

[0043] In one embodiment, the electron beam exposure used for material removal depends on the material to be removed and the amount of material present. For example, if the material to be removed has a high nuclear density, the electron beam is expected to heat the material more rapidly. Thus, if the material to be removed has a large nuclear density, the electron beam exposure is decreased. Alternatively, the beam energy and beam current may be decreased. Similarly, if the material to be removed has a low nuclear density, the electron beam does not rapidly heat the material. Thus, if the material has a low nuclear density, it is necessary to increase the electron beam exposure. Also, if the amount of material to be removed is large, correspondingly, it is necessary to increase the electron beam exposure.

[0044] Once the electron beam exposure is determined according to the material to be removed and the amount of material removal, the characteristics of the electron beam can be determined. For example, for a specific material, the electron energy and electron current (which may depend on the electron emitter), as well as the rotation speed, electron beam size, and duration can be determined.

[0045] For example, in a situation where the material to be removed is a metal-containing photoresist material, the electron beam has a beam energy in the range of 2 keV to 20 keV, a beam current in the range of 1 mA to 30 mA, a rotation speed in the range of 500 RPM to 3000 RPM, and a beam width in the range of 0.5 mm to 2 mm, and may have an electron emitter emission time sufficient for the electron beam to be incident on all parts of the peripheral region of the substrate in the range of 2 to 50 times. In one example, the beam type of the electron beam is continuous. In another example, the beam type of the electron beam is pulsed, and in this case, the electron beam has a pulse period in the range of 10 ns to 100 ns and a duty cycle in the range of 30% to 70%. An electron beam having a beam energy in the range of 2 keV to 20 keV and a beam current in the range of 1 mA to 30 mA has sufficient energy and current to raise the temperature of the material up to the range of 1000 K to 2000 K. At this temperature, the metal-containing photoresist volatilizes. For other materials, different characteristics of the electron beam may be required in terms of, for example, beam energy, beam current, beam size, and time. In another example, a material having a large nuclear density is more sensitive to the electron beam, the beam energy of the electron beam, or the beam current, and can raise the temperature of the material to the point of volatilizing the material even under weaker conditions (compared to a material having a small nuclear density).

[0046] In another example, in a situation where an electron beam is emitted by a single electron emitter and material is removed from both the working surface and the back surface of the peripheral region of the substrate, the electron emitter is configured to emit two electron beams: the first electron beam has a first set of characteristics and volatilizes the material on the first surface of the peripheral region (for example, the first surface is the closest to the electron emitter), and the second electron beam has a second set of characteristics and volatilizes the material on the second surface of the peripheral region (the second surface is on the opposite side of the first surface). For example, the first surface is the working surface of the substrate, and the second surface is the back surface of the substrate. The first electron beam has a beam energy in the range of 2 keV to 20 keV and a beam current in the range of 1 mA to 30 mA, and the second electron beam has a beam energy in the range of 50 keV to 100 keV and a beam current in the range of 1 mA to 30 mA. In one example, the beam species of both the first electron beam and the second electron beam are continuous. In another example, the beam species of both the first electron beam and the second electron beam are pulsed, having a pulse time in the range of 10 ns to 100 ns and a duty cycle in the range of 30% to 70%. In another example, the beam species of both the first electron beam and the second electron beam are pulsed, with different pulse times or duty cycles. In another example, one beam species of the first or second electron beam is continuous and the other beam species is pulsed. Both the first electron beam and the second electron beam may be on for a time sufficient for the first and second electron beams to be incident on all parts of the corresponding surfaces of the peripheral region of the substrate in the range of 2 to 50 times. Both the first and second electron beams may have the same beam width. In such an example, for example, the electron emitter may be configured to emit the first electron beam to remove material from the first surface of the substrate, and then the electron emitter may be configured to emit the second electron beam to remove material from the second surface of the substrate.

[0047] In one embodiment, an air flow system is provided that supplies gas across the entire substrate. The air flow system that supplies gas across the entire substrate suppresses the deposition of volatilized materials on the substrate or in the material removal system, preventing contamination. The gas is supplied at a flow rate sufficient to entrain the volatilized materials. Examples of gases supplied by the air flow system include air, N 2 , an inert gas (such as argon), or a combination thereof.

[0048] Also in one embodiment, a stop threshold is determined for use in determining when to stop the material removal process using measurement data. The measurement data includes, but is not limited to, measurement image data, sensor data (such as temperature data, detected volatilized material data), etc., and is provided to a controller that controls the material removal system. The controller determines adjustments to the electron beam characteristics based on the measurement data. For example, if the measurement data suggests that material has been removed from the peripheral region of the substrate, the controller may turn off the electron emitter. In another example, if the measurement image data suggests that material remains on the substrate after a specified electron beam exposure, the controller may adjust the electron emitter to continue generating the electron beam and continue the material removal process. In another example, if the temperature data suggests that the substrate is extremely hot, the controller may adjust the electron emitter so that the electron beam generated by the electron emitter reduces the degree of heating of the substrate. In yet another example, if the measurement data suggests that no volatilized material is detected in the gas flow across the surface of the substrate, the controller may determine that material has already been removed from the peripheral region of the substrate and stop the electron emitter.

[0049] FIG. 4 shows a first example of a material removal system 400 according to one embodiment shown in the present application. The material removal system 400 may be used for operations such as the removal of material at the peripheral edge of a substrate. The material to be removed may be on the working surface of the substrate, the back surface of the substrate, the edge of the substrate, or a combination thereof. The material removal system 400 has a chamber 402 having an upper portion 404, a wall 406, and a bottom 408. The chamber 402 may be sealed or open.

[0050] The material removal system 400 has a substrate holder 105, and the substrate holder 105 is coupled to a motor 412 that can rotate the substrate holder 105. The substrate 110 to be processed can be attached to the substrate holder 105. The substrate holder 105 may hold the substrate 110 by vacuum suction. The substrate 110 may be moved into the chamber 402 via a load or unload port.

[0051] A showerhead 418 disposed above the substrate holder 105 is configured to direct a gas 420 across the working surface of the substrate 110. The showerhead 418 is part of an air flow system and is configured to provide a gas flow above the substrate 110. The showerhead 418 may direct the gas 420 across the entire surface of the substrate 110 or across a specific portion of the surface of the substrate 110. The gas 420 is supplied at a sufficient flow rate to carry the volatilized material. Examples of the gas 420 include air, N 2, an inert gas (such as argon), or a combination thereof is included. The gas 420 is recovered via an exhaust system (e.g., an outlet 422 and a vacuum pump 424). In a poor-quality air flow, undesirable vortices may form, and volatile materials may deposit on the chamber 402 or the substrate 110. By installing the showerhead 418 directly above the substrate 110 and configuring the showerhead 418 such that the gas 420 is directly induced across the entire surface of the substrate 110, the advantage is obtained that the vortices can be suppressed or eliminated. The showerhead 418 across the entire substrate 110 provides a smooth air flow in the radial and azimuthal directions. Subsequently, the outlet 422 can recover the air flow along with the volatile material 428 that may contaminate subsequent substrate processing processes.

[0052] The material removal system 400 has an electron emitter 426, and the electron emitter 426 is configured to emit an electron beam having beam energy, beam current, beam species, and time in the surrounding area of the substrate 110 (e.g., beam width and time). The electron beam heats and volatilizes the material on the substrate 110. As shown in FIG. 4, the electron emitter 426 is oriented toward the working surface of the substrate 110. Also, the material removal system 400 may have additional electron emitters oriented to other portions of the substrate 110.

[0053] The electron emitter 426 may be coupled to an alignment system 427. With the alignment system 427, the electron emitter 426 can be moved or rotated (or both moved and rotated) along an axis parallel to the working surface of the substrate 110, and the electron beam emitted by the electron emitter 426 is induced in the surrounding area of the substrate 110. In one example, the electron emitter 426 is aligned with the surrounding area of the substrate 110 using the alignment system 427. The alignment of the electron emitter 426 may be performed for each substrate loaded into the material removal system 400. Alternatively, the electron emitter 426 may be aligned for each substrate type loaded into the material removal system 400. In other words, when a plurality of substrates of the same type (e.g., the same processing lot) are processed by the material removal system 400, the electron emitter 426 may be aligned only for the first substrate and may not be aligned for each remaining substrate of the same processing lot.

[0054] The volatilized material 428 is entrained with the gas 420 supplied by the shower head 418 and is recovered by the vacuum pump 424 through the outlet 422. Alternatively, as described above, the electron emitter 426 emits a plurality of electron beams (having different beam energies, beam currents, and times) to volatilize materials on different surfaces of the substrate 110.

[0055] Also, in a situation where the material removal system 400 is used for spin-coating film formation, the nozzle 430 is configured to disperse a spin-coating material in liquid form onto the substrate 110. This is rotated at high speed by the substrate holder 105. As shown in FIG. 4, the nozzle 430 is part of the shower head 418. However, alternative embodiments are possible. For example, the nozzle 430 may enter the chamber 402 through the wall 406 and be directed above the center of the substrate 110.

[0056] The controller 440 (shown in dashed lines), which is coupled to various components of the material removal system 400 (e.g., substrate holder 105, motor 412, vacuum pump 424, electron emitter 426, etc.) or sensors or measurement tools (e.g., sensors or measurement tools disposed within the chamber 402, substrate holder 105, motor 412, vacuum pump 424, electron emitter 426, etc.), can measure operating variables such as temperature, the amount of volatile material, and the amount of non-volatile material remaining on the substrate 110, and can adjust electron beam parameters (e.g., beam energy, beam current, beam width, beam species, exposure, etc.), substrate rotation speed, etc., facilitating the control of the material removal process.

[0057] For example, when the controller 440 detects that the temperature of the substrate 110 is high, it can turn off or decrease the beam energy and beam current of the electron beam, and increase the rotation speed, etc., to assist in protecting the substrate 110 from overheating. In another example, the controller 440 uses measurement data (e.g., a measurement image of the amount of material in the surrounding area of the substrate 110 from a camera) to adjust the beam parameters and control the removal of material from the surrounding area. In this example, the controller 440 uses the measurement image to determine the amount of residual material in the surrounding area of the substrate 110, and when the material is removed, the controller 440 may stop the radiation from the electron emitter 426. In this example, when it is determined by the controller 440 that time has passed and material remains in the surrounding area of the substrate 110, the controller 440 may adjust the beam parameters and accelerate the rate at which the material is volatilized. In addition to temperature and image measurement data, the controller 440 may detect the presence or absence of volatile material 428 entrained in the gas 420 and adjust the beam parameters.

[0058] In certain embodiments, the chamber 402 may be electrically grounded to provide electrostatic protection. Similarly, the electron emitter 426 may be electrically grounded. Also, an X-ray shield may be introduced within the chamber 402, around the substrate 110, around the material removal system 400, or combinations thereof, to provide protection from X-rays generated by the electron emitter 426.

[0059] FIG. 5A shows a top view of a first example of a chamber 500 of a material removal system 400 according to an embodiment of the present disclosure. The chamber 500 has an outlet 422. The outlet 442 is disposed around the substrate 110 to collect the gas 420 and the volatile material 428 and to prevent the volatile material 428 from depositing on the working surface of the substrate 110. As shown in FIG. 5A, at least one outlet 422 is disposed near the electron emitter 426 to enhance the collection of the volatile material 428 formed there. Four outlets 422 are shown in FIG. 5A, but more or fewer outlets 422 are possible.

[0060] FIG. 5B shows a top view of a second example of a chamber 550 of a material removal system 400 according to an embodiment of the present disclosure. The chamber 550 has an outlet 422. The outlet 422 is disposed around the substrate 110 to collect the gas 420 and the volatile material 428 and to prevent the volatile material 428 from depositing on the working surface of the substrate 110. The collection of the gas 420 and the volatile material 428 is enhanced by a shield 555 that forms a barrier around the substrate 110 and assists in guiding the gas 420 and the volatile material 428 to the outlet 422. Four outlets 422 are shown in FIG. 5B, but more or fewer outlets 422 are possible. Also, the shield 555 is shown as completely surrounding the substrate 110, but embodiments of the shield 555 that surround only a portion of the substrate 110 are possible.

[0061] FIG. 6 shows an isometric view of a portion of a material removal system 600 according to an embodiment of the present disclosure. It is emphasized that the air flow is entrained by the rapidly rotating substrate. The material removal system 600 has a substrate 110 in a substrate holder (not shown in FIG. 6), and the substrate holder is configured to rotate the substrate 110 at a particular speed. The material removal system 600 also has an electron emitter 305, and the electron emitter 305 is configured to emit an electron beam 310 with a specified electron energy and a specified current. The electron beam 310 is incident on the spin-coated material of the substrate 110, heating the spin-coated material and vaporizing the spin-coated material. In FIG. 6, the volatile material is indicated by the dashed line 315.

[0062] For example, the gas 605 introduced by the showerhead is entrained by the rapidly rotating substrate 110. The entraining gas 605 also discharges the volatile material generated by the electron emitter 305 and the electron beam.

[0063] In certain embodiments, an air flow system is provided that supplies gas over a local portion of the substrate. The gas is supplied at a flow rate sufficient to entrain the volatile material. The air flow system that supplies gas over a local portion of the substrate, proximate to the location where the volatile material is formed, helps to prevent the volatile material from depositing on the substrate or the material removal system and contaminating them, while keeping the complexity of the air flow system low.

[0064] FIG. 7 shows a diagram of a second example of a material removal system 700 according to an embodiment of the present disclosure. The material removal system 700 may be used for operations such as the removal of material at the peripheral edge of the substrate. The material to be removed may be on the working surface of the substrate, the back surface of the substrate, the edge of the substrate, or a combination of these locations. The material removal system 700 has a chamber 402 with an upper portion 404, a wall 406, and a bottom 408. The chamber 402 may be sealed or open.

[0065] The material removal system 700 has a substrate holder 105. The substrate holder 105 is coupled to a motor 412 that can rotate the substrate holder 105. The substrate 110 to be processed can be attached to the substrate holder 105. The substrate holder 105 may hold the substrate 110 by vacuum suction. The substrate 110 may be moved into the chamber 402 via a load or unload port.

[0066] A gas nozzle 705 disposed above the substrate holder 105 is part of an air flow system, which is configured to direct a gas 420 onto a part of the surface of the substrate 110 near the position where the electron beam generated by the electron emitter 426 volatilizes material in the surrounding area of the substrate 110. The gas nozzle 705 is oriented towards the electron emitter 426 such that the gas 420 flows towards the electron emitter 426. The gas 420 is supplied at a sufficient flow rate so that the volatile material 428 is entrained. The gas 420 entrains the volatile material 428, and both gases are discharged via an outlet 422 by a vacuum pump 424. The electron emitter 426 may be coupled to an alignment system 427. By the alignment system 427, the electron emitter 426 can be moved or rotated (or both moved and rotated) along an axis parallel to the working surface of the substrate 110, and the electron beam emitted by the electron emitter 426 is directed into the surrounding area of the substrate 110.

[0067] Also, in a situation where the material removal system 400 is used for spin - coating film formation, the nozzle 430 is configured to disperse a spin - coating material in liquid form onto the substrate 110. This is rotated at a high speed by the substrate holder 105. As shown in FIG. 7, the nozzle 430 may enter the chamber 402 through the upper part 404 and be directed to the center of the substrate 110 or near it. However, other embodiments are also possible. For example, the nozzle 430 may enter the chamber 402 through the wall 406 and be directed above the center of the substrate 110.

[0068] Various components of the material removal system 400 (e.g., the substrate holder 105, the motor 412, the vacuum pump 424, the electron emitter 426, etc.), or a controller 440 (shown in dashed lines) coupled to a sensor or measurement tool (e.g., a sensor or measurement tool disposed within the chamber 402, the substrate holder 105, the motor 412, the vacuum pump 424, the electron emitter 426, etc.) can measure operating variables such as temperature, the amount of volatile material, the amount of non-volatile material, etc., and can adjust electron beam parameters (e.g., beam energy, beam current, beam width, beam species, exposure, etc.), the substrate rotation speed, etc., facilitating the control of the material removal process.

[0069] For example, when the controller 440 detects that the temperature of the substrate 110 is high, it turns off or reduces the beam energy and beam current of the electron beam and increases the rotation speed, etc., to assist in protecting the substrate 110 from overheating. In another example, the controller 440 uses measurement data (e.g., a measurement image of the amount of material in the surrounding area of the substrate 110 from a camera) to adjust the beam parameters and control the removal of material from the surrounding area. In this example, the controller 440 uses the measurement image to determine the amount of residual material in the surrounding area of the substrate 110, and when the material is removed, the controller 440 may stop the radiation from the electron emitter 426. In this example, when it is determined by the controller 440 that time has passed and material remains in the surrounding area of the substrate 110, the controller 440 may adjust the beam parameters and accelerate the rate at which the material is volatilized. In addition to temperature and image measurement data, the controller 440 may detect the presence or absence of volatile material 428 entrained in the gas 420 and adjust the beam parameters.

[0070] In one embodiment, to provide electrostatic protection, the chamber 402 may be electrically grounded. Similarly, the electron emitter 426 may be electrically grounded. Also, for protection from X-rays generated by the electron emitter 426, an X-ray shield may be introduced within the chamber 402 and around the substrate 110.

[0071] FIG. 8A shows a top view of a first example of a chamber 800 of a material removal system 700 according to an embodiment of the present disclosure. The chamber 800 has an outlet 422. The outlet 442 is disposed near an end of the substrate 110, collects the gas 420 and the volatile material 428, and suppresses the deposition of the volatile material 428 on the working surface of the substrate 110. As shown in FIG. 8A, the outlet 422 is disposed near the electron emitter 426, enhancing the collection of the volatile material 428 formed there. Although only one outlet 422 is shown in FIG. 8A, more outlets 422 are possible.

[0072] FIG. 8B shows a top view of a second example of a chamber 850 of a material removal system 700 according to an embodiment of the present disclosure. The chamber 850 has an outlet 422. The outlet 422 is disposed at an end of the substrate 110, collects the gas 420 and the volatile material 428, and suppresses the deposition of the volatile material 428 on the working surface of the substrate 110. The collection of the gas 420 and the volatile material 428 is enhanced by a shield 855 that forms a barrier around a portion of the substrate 110, assisting in guiding the gas 420 and the volatile material 428 to the outlet 422. Although only one outlet 422 is shown in FIG. 8B, more outlets 422 are possible. Also, although the shield 855 is shown as completely surrounding a portion of the substrate 110, embodiments of the shield 855 that surround other portions of the substrate 110 are possible.

[0073] FIG. 9 shows an example flowchart of a processing process 900 used when removing material from a peripheral end of a substrate using an electron beam according to an embodiment of the present disclosure. The processing process 900 may show the operations occurring in the material removal system when the material removal system removes material from the peripheral end of the substrate using an electron beam.

[0074] The processing process 900 starts when the material removal system receives a substrate (block 905). The substrate may be placed within a substrate holder configured to rotate the substrate at a certain rotational speed. In some embodiments, the electron emitter is aligned such that the electron beam emitted from the electron emitter is accurately positioned in the peripheral region of the substrate. Rotation of the substrate is initiated (block 907). The substrate supported by the substrate holder is rotated by the substrate holder. The air flow system, the exhaust system, and the electron emitter are turned on (block 909). The air flow system and the exhaust system, which may have a showerhead or gas inlets and outlets, provide an air flow at a specific flow rate across the surface of the wafer, exhausting the volatile material generated by the electron beam and preventing the volatile material from depositing on the substrate or in the material removal system. The electron emitter is configured to generate an electron beam having a beam energy and a beam current. Also, the electron beam has an exposure, which depends on the material to be removed from the substrate. The electron beam has a beam species, which may be, for example, pulsed or continuous. Rotation of the substrate is initiated before the air flow system, the exhaust system, and the electron emitter are turned on, and the substrate reaches a specific rotational speed. In some embodiments, the air flow system and the exhaust system are turned on before the electron emitter is turned on, and are assisted to ensure that there is sufficient air flow to entrain the volatile material before vaporization of the material begins. In other words, the flow rate of the air flow is sufficient to entrain the volatile material. In some embodiments, the air flow system and the exhaust system are continuously turned on while the material removal system is in operation.

[0075] The material removal system (e.g., its controller) performs a check (block 911) to determine whether a stop threshold is met. For example, the stop threshold specifies the time the electron beam is turned off. The stop threshold may be specified, for example, with respect to electron beam exposure. The material removal system may perform a check to determine whether the material to be removed was exposed to the electron beam during a particular electron beam exposure. The stop threshold may be time (such as the time the electron emitter was on), the number of rotations of the substrate (e.g., the count of substrate rotations since the electron emitter was turned on), etc. For example, the stop threshold may be specified by measurement data (such as a measurement image, a temperature reading, volatile material sensor data, etc.). For example, the measurement data is used by the controller of the material removal system to determine whether the material to be removed has actually been removed. For example, once the material is removed, the stop threshold is met. In another example, a temperature reading is used by the controller to control the electron beam emitted by the electron emitter. For example, if the temperature reading suggests that the substrate is overheating, the controller may adjust the beam parameters or turn off the beam to prevent the substrate from overheating. The stop threshold may be specified, for example, as a combination of a particular electron beam exposure and measurement data.

[0076] If the stop threshold is not met, the material removal system removes material from the peripheral region of the substrate and continues the check until the stop threshold is met.

[0077] In block 911, if the stop threshold is met, the material removal system turns off the air flow system, the exhaust system, and the electron emitter (block 913). The electron emitter is turned off before the air flow system and the exhaust system, and the removal of any residual volatile material may be reliably assisted. In some embodiments, the air flow system and the exhaust system are maintained on while the material removal system is in operation. The material removal system stops the rotation of the substrate (block 915) and removes the substrate from the substrate holder (block 917). The substrate may be further processed in the same or a different processing tool.

[0078] In certain embodiments, material removal occurs in a spin coating station, and the material removal process may be performed after the spin coat material is disposed on the substrate. Before the start of the material removal process, an amount of time may be allowed to elapse to allow the spin coat material to at least partially cure. In certain embodiments, during the spin coating process, the exhaust system remains on, but the air flow system is turned off. This is because the air flow can deform the film of the spin coat material. In certain embodiments, during the spin coating process, both the exhaust system and the air flow system are turned off. In certain embodiments, material removal occurs within the spin coating station, and after the spin coat material is disposed on the substrate, the substrate is moved to a heat treatment station. After the spin coat material cures upon heating, the substrate is returned to the spin coating station for material removal.

[0079] In the foregoing description, specific details such as the particular shape of the processing system, as well as the various members and processes used, have been described. However, it should be noted that the described technology may be implemented in other embodiments that are apart from these specific examples, and such details are for illustrative purposes and not limiting. The illustrated embodiments have been described with reference to the accompanying drawings. Similarly, for purposes of explanation, specific numbers, materials, and configurations have been shown to provide a complete understanding. However, the embodiments may be implemented without such specific details. Members having substantially the same functional structure are denoted by like reference numerals, and thus redundant descriptions are omitted.

[0080] To aid understanding of the various embodiments, the various techniques have been described as a plurality of distinct operations. The order of the description should not be construed as necessarily depending on the order of implementation of these operations. In fact, these operations do not necessarily have to be implemented in the order described. The described operations may be implemented in a different order from that of the described embodiments. Various additional operations may be implemented, or the described operations may be omitted in additional embodiments.

[0081] As used herein, "substrate" generally represents what is processed by the present invention. The substrate may have any material portion or device, particularly a semiconductor or other electronic device structure. For example, it may be a semiconductor wafer, a base substrate structure such as a rectangle, or a layer such as a thin film disposed on or above the base substrate structure. Thus, the substrate is not limited to any particular base structure, or patterned or unpatterned underlying or upper layer, but rather is contemplated to include any such layer or base structure, as well as any combination of layers or base structures. The description refers to a particular type of substrate, but this is merely for illustrative purposes.

[0082] The present invention has been described with reference to an exemplary embodiment, but this description is not intended to be construed in a limiting sense. Various modifications and combinations of the shown embodiments, as well as other embodiments of the present invention, will be apparent to those skilled in the art with reference to the description. Accordingly, the appended claims are intended to cover any such modifications or embodiments.

Description of Reference Numerals

[0083] 105 Substrate Holder 110 Substrate 115 Peripheral Region 300 Material Removal System 305 Electron Emitter 310 Electron Beam

Claims

1. A substrate processing system, comprising: a processing chamber; a substrate holder disposed within the processing chamber, configured to hold a substrate and rotate the substrate about an axis perpendicular to an operating surface of the substrate; an electron emitter adapted to emit a first electron beam induced on a first surface of a peripheral region of the substrate, the first electron beam having a first beam energy and a first beam current sufficient to volatilize material from the first surface of the peripheral region of the substrate; an air flow system configured to induce a gas flow across the operating surface of the substrate; an exhaust system configured to collect the gas containing the material volatilized from the peripheral region; wherein the air flow system has a shower head configured to induce the gas flow from a center of the operating surface of the substrate toward a periphery of the operating surface, and the gas flows toward the exhaust system; the electron emitter is further adapted to emit a second electron beam induced on the first surface of the peripheral region of the substrate; the second electron beam has a second beam energy and a second beam current sufficient to volatilize the material from a second surface of the peripheral region of the substrate through the first surface of the peripheral region of the substrate; the second surface is opposite to the first surface, the substrate processing system.

2. The substrate processing system according to claim 1, further comprising a nozzle adapted to disperse the material in a fluid form onto the operating surface of the substrate held and rotated by the substrate holder, and a spin coat film is formed on the operating surface of the substrate.

3. The substrate processing system according to claim 1, wherein the first beam energy is between 2 KeV and 20 KeV; and the first beam current is between 1 mA and 30 mA.

4. The substrate processing system according to claim 1, wherein the second beam energy is between 50 KeV and 100 KeV; and the second beam current is between 1 mA and 30 mA.

5. The substrate processing system according to claim 1, wherein the substrate holder is configured to rotate the substrate at a speed between 500 RPM and 3000 RPM.

6. The substrate processing system according to claim 1, wherein the electron emitter emits the first electron beam during a corresponding time period between 2 rotations and 50 rotations of the substrate.

7. The substrate processing system according to claim 1, further comprising a controller configured to adjust parameters of the first electron beam according to measurement data regarding the substrate.

8. A method for processing a substrate, comprising: receiving the substrate in a substrate holder of a processing chamber; rotating the substrate around an axis perpendicular to an operating surface of the substrate; turning on an air flow system to induce a gas flow from a center of the operating surface of the substrate toward a periphery of the operating surface; exposing a peripheral region of the substrate to a first electron beam and a second electron beam to volatilize material from the peripheral region of the substrate, wherein the first electron beam has a first beam energy and a first beam current sufficient to volatilize the material from a first surface of the peripheral region of the substrate, the second electron beam is induced to the first surface of the peripheral region of the substrate, the second electron beam passes through the first surface of the peripheral region of the substrate, and the second electron beam has a second beam energy and a second beam current sufficient to volatilize the material from a second surface of the peripheral region of the substrate, and the second surface is on an opposite side of the first surface; A method comprising the above steps.

9. The method according to claim 8, wherein the gas flow has a flow rate sufficient to avoid deposition of the volatilized material on the operating surface of the substrate.

10. The method according to claim 8, wherein the first electron beam has a first beam energy between 2 keV and 20 keV and a first beam current between 1 mA and 30 mA.

11. The method according to claim 8, wherein the second electron beam has a second beam energy between 50 keV and 100 keV and a second beam current between 1 mA and 30 mA.

12. The method according to claim 8, wherein the substrate is rotated at a speed between 500 RPM and 3000 RPM.

13. A method for processing a substrate, comprising: receiving the substrate; A step of flowing a gas across the working surface of the substrate, wherein the gas is induced to flow from the center of the working surface of the substrate towards the periphery of the working surface and flows at a specific flow rate; A step of volatilizing a part of the material in the peripheral region of the substrate by exposing the peripheral region of the substrate to an electron beam from an electron emitter while rotating the substrate around an axis perpendicular to the working surface of the substrate; A step of confirming that a stop threshold is met and, based on this, turning off the electron emitter; comprising; The electron beam has a first electron beam and a second electron beam; The first electron beam has a first beam energy and a first beam current sufficient to volatilize the material from a first surface of the peripheral region of the substrate; The second electron beam is induced to the first surface of the peripheral region of the substrate, and the second electron beam passes through the first surface of the peripheral region of the substrate and has a second beam energy and a second beam current sufficient to volatilize the material from a second surface of the peripheral region of the substrate, and the second surface is on the opposite side of the first surface.

14. The method according to claim 13, wherein the stop threshold is based on the rotational speed of the substrate.

15. The method according to claim 13, wherein the stop threshold is based on measurement data.

16. The method according to claim 13, wherein the specific flow rate is based on a flow rate sufficient to prevent the volatilized material from depositing on the working surface of the substrate.

17. A method for processing a substrate, comprising: A step of placing the substrate in a substrate holder, wherein the substrate holder is configured to rotate the substrate around an axis perpendicular to the working surface of the substrate; A step of arranging an electron emitter in the peripheral region of the substrate; A step of starting the rotation of the substrate by the substrate holder; A step of turning on an air flow system, an exhaust system, and the electron emitter, wherein The air flow system has a shower head configured to induce a gas flow from the center of the working surface of the substrate towards the periphery of the working surface, the gas flows towards the exhaust system, and the activated electron emitter emits a first electron beam and a second electron beam. The first electron beam has a first beam energy and a first beam current sufficient to volatilize material from a first surface of the peripheral region of the substrate, and the material evaporates from the first surface of the peripheral region of the substrate by the first electron beam. The second electron beam is induced on the first surface of the peripheral region of the substrate, the second electron beam passes through the first surface of the peripheral region of the substrate, and has a second beam energy and a second beam current sufficient to volatilize the material from a second surface of the peripheral region of the substrate, the second surface being on the opposite side of the first surface, and the material evaporates from the second surface of the peripheral region of the substrate by the second electron beam; when a stop threshold is satisfied, turning off the air flow system, the exhaust system, and the electron emitter; A method comprising the steps of:

18. The method according to claim 17, wherein the exhaust system is configured to collect a gas containing the material evaporated from the peripheral region.

19. The method according to claim 17, wherein the first electron beam has a first beam energy between 2 keV and 20 keV and a first beam current between 1 mA and 30 mA.

20. The method according to claim 17, wherein the second beam energy is between 50 keV and 100 keV and the second beam current is between 1 mA and 30 mA.

21. The method according to claim 17, wherein the substrate holder rotates the substrate at a rotational speed between 500 RPM and 3000 RPM.

22. The method according to claim 17, wherein the electron emitter emits the first electron beam for a time corresponding to between 2 and 50 rotations of the substrate.

23. The method according to claim 17, further comprising adjusting parameters of the first electron beam according to measurement data regarding the substrate.

24. The method according to claim 23, wherein the measurement data includes an image of a residual amount of the material in the peripheral region of the substrate.

Images