JP2015216274A - Electron beam irradiation device, mark position detection method, determination method of time for replacement of metal film, and manufacturing method of article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam irradiation device capable of slowing down the rate of deposition to a backscattered electron detector.SOLUTION: An electron beam irradiation device 1 has a detector 6 for detecting electrons emitted from an irradiated object by electron beam irradiation, and a cover 14 having a metal film 16 between the detector 6 and irradiated object. The detector 6 detects electrons transmitted through the metal film 16.

Description

  The present invention relates to an electron beam irradiation apparatus, a mark position detection method, a metal film replacement time determination method, and an article manufacturing method.

  In an electron beam irradiation device such as an electron beam drawing device or a scanning electron microscope, if an electron beam is irradiated to hydrocarbon molecules remaining in a vacuum chamber or hydrocarbon molecules generated by decomposition of a resist, etc. Is produced as a main component. Since this substance exists as an organic substance even if the main component is carbon, it has low conductivity and can be regarded as an insulating substance. These insulating materials tend to adhere in the vicinity of the generation point, and are particularly likely to adhere to the backscattered electron detector provided below the lens barrel from which the electron beam is emitted. Since an electric charge is accumulated when an insulating material adheres, a phenomenon in which an orbit of an electron beam irradiated toward a substrate becomes unstable or a drift occurs is known.

  The above phenomenon is a disadvantageous phenomenon in a drawing apparatus that forms a pattern on a resist using an electron beam. This is because the orbital deviation of the electron beam misrecognizes the position of the mark in the drawing pattern or the baseline measurement.

  Therefore, in Patent Document 1, a conductor having a gap between an object to be irradiated and a backscattered electron detector (a thin aluminum wire formed in a cross in an aluminum ring) is arranged to charge the backscattered electron detector. Discloses a technique for reducing the influence of the electron beam on the orbit of the electron beam. In Patent Document 2, a shield plate is arranged between the irradiated object and the reflected electron detector when the reflected electron detector is not used, and the reflected plate is detected by retracting the shield plate when the reflected electron detector is used. The technology to do is disclosed.

JP-A-1-248517 JP-A-4-147611

  When the conductor described in Patent Document 1 is used, there is a possibility that an insulating substance caused by hydrocarbon molecules that have passed through the provided gap may adhere to the backscattered electron detector. Further, even if the shielding plate described in Patent Document 2 is used, there is a possibility that an insulating material may adhere to the reflected electron detector while the shielding plate is retracted. In order to prevent the electron beam trajectory from being bent by the insulating material attached to the reflected electron detector, the reflected electron detector needs to be replaced before a large amount of the insulating material is attached.

  However, if the backscattered electron detector is frequently replaced, it is necessary to release the vacuum chamber to the atmosphere or to re-evacuate after the atmosphere is released, so that the operation time of the drawing apparatus is greatly reduced. Therefore, it is desired to make the same backscattered electron detector usable longer.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electron beam irradiation apparatus capable of reducing the rate of adhesion to a backscattered electron detector as compared with the prior art.

  An electron beam irradiation apparatus according to the present invention includes a detector for detecting electrons emitted from an irradiated object by electron beam irradiation, and a cover having a metal film between the detector and the irradiated object, The detector detects electrons transmitted through the metal film.

  According to the electron beam irradiation apparatus of the present invention, it is possible to slow down the adhesion rate to the backscattered electron detector as compared with the prior art.

1 is a configuration diagram of a drawing apparatus according to a first embodiment. The figure explaining the structure of a cover. The figure explaining an exchange stand. The figure explaining the replacement | exchange method of a cover. The block diagram of the cover which concerns on 2nd Embodiment. The block diagram of the cover which concerns on 3rd Embodiment. The block diagram of the cover which concerns on 4th Embodiment. The block diagram of the cover which concerns on 5th Embodiment. The figure explaining the 1st judgment method of cover replacement time. The flowchart regarding the 1st determination method of cover replacement time. The figure explaining the 2nd determination method of cover replacement time. Baseline measurement flowchart

  In an electron beam drawing apparatus according to the following embodiments, a metal thin film (metal film) (hereinafter referred to as a thin film) is provided between an object to be irradiated and a detection layer of a reflected electron detector (hereinafter referred to as a detector). ) Is disposed. Insulating substances mainly composed of carbon generated from hydrocarbons (hereinafter referred to as insulating substances) adhere to the thin film, while the detector can detect electrons through the metal thin film. Therefore, the deposition rate of the insulating material that adheres to the detector can be reduced.

[First Embodiment]
(Configuration diagram of drawing device)
FIG. 1 shows a drawing apparatus 1 that forms a pattern on a wafer 4 (on a substrate) using an electron beam. The drawing apparatus 1 includes a lens barrel 2. The lens barrel 2 includes an electron source 3 that emits an electron beam, and an electron optical system 5 that focuses the electron beam emitted from the electron source 3 onto a wafer 4. Have. Further, a detector 6 for detecting reflected electrons (electrons coming from the irradiated object) reflected near the surface of the wafer 4 among the electrons irradiated on the wafer 4 is arranged below the lens barrel 2. ing. The detector 6 is preferably an amplification type detector that is not easily affected by secondary electrons in view of a method for detecting reflected electrons described later. Further, among the amplification type backscattered electron detectors, those having a photodiode as an electron detection layer are preferable because of their small size.

  On the stage (moving body) 7, the distance between the wafer 4 coated with the resist 8 and the optical axis of the base line (optical sensor 28 used for detecting distortion of the wafer 4 and the like) and the optical axis of the electron optical system 5. ) There are a reference table 10 and an optical sensor 28 on which a mark 9 used for measurement is formed. In the present embodiment, the mark 9 and the upper surface of the reference table 10 around the mark 9 are objects to be irradiated when the reflected electrons are detected. Further, an exchange table 11 for exchanging a cover 14 described later is placed. The controller 12 moves the stage 7 in the X, Y, and Z axis directions. The detector 6 detects the irradiation position of the electron beam by detecting the reflected electrons of the electron beam emitted from the lens barrel 2 toward the wafer 4. A cover 14 supported by a holder 13 is disposed between the detector 6 and the resist 8.

  A member placed on the lower part of the lens barrel 2 and the stage 7 is in the vacuum chamber 20, and a vacuum pump (not shown) maintains the inside of the vacuum chamber 20 in a vacuum atmosphere. Between the vacuum chamber 20 and the atmospheric chamber 21, there is a load lock chamber 22 that is an intermediate chamber for maintaining a vacuum atmosphere in the vacuum chamber 20.

  FIG. 2 shows the configuration of the cover 14. FIG. 2A is a view of the cover 14 viewed from the wafer 4 side. The thin film 16 is held by a ring-shaped conductive metal holding portion (supporting member) 15. In the center of the thin film 16, a hole for allowing an electron beam to pass during drawing is formed. Each holder 13 is L-shaped and supports the cover 14 so that it does not fall. FIG. 2B is a cross-sectional view of the cover 14. The thin film 16 is thinner than the holding part 15 and has a structure in which the thin film 16 is sandwiched between two holding parts 15 having the same shape.

  An insulating material generated when the electron beam is irradiated by disposing the thin film 16 between the detector 6 and the surface of the wafer 4 so as to cover the surface of the detection layer of the detector 6 (the surface of the detector). Adheres to the thin film 16. Thereby, it plays the role which prevents adhering to the detector 6. FIG.

  The thin film 16 is preferably a light metal capable of forming a thin film having an atomic number of 30 or less and having conductivity. For example, aluminum (Al), nickel (Ni), titanium (Ti), copper (Cu) and the like can be mentioned, and Al is particularly preferable. The number of electrons passing through the thin film 16 and the loss of energy depend on the atomic number and density. If the thin film has the same thickness, the smaller the atomic number, the smaller the energy loss of the electron beam that passes through the thin film 16 and the more efficient detection. This is because electrons can be incident on the vessel 6.

  If the energy of the electron beam incident on the resist 8 is 100 keV, the average energy of the reflected electrons is about 70 keV. For example, even if the thin film 16 formed of Al having a thickness of 1 μm is disposed on the front surface of the detector 6, the transmittance of the reflected electrons in the thin film 16 incident on the thin film 16 is 99.9%. The energy loss of the electron beam is about 3%. Therefore, the detection accuracy by the detector 6 can be sufficiently maintained.

  For example, even if the number of electrons passing through the thin film 16 is about 20%, detection is possible if the signal amplification factor of the detector 6 is increased. In this case, if the thin film 16 is Al, the film can be formed with a film thickness of 22 μm, and if it is Ni, the film can be formed with a film thickness of 7 μm.

  The number of electrons transmitted through the thin film 16 depends on the film thickness, but it is preferable that at least 5% of the number of incident electrons is transmitted, more preferably 50% or more. In the case of Al, a preferable film thickness is 0.5 μm or more and 25 μm or less, and a more preferable film thickness is 2 μm or more and 14 μm or less. In the case of Ni, a preferable film thickness is 0.5 μm or more and 8 μm or less, and a more preferable film thickness is 2 μm or more and 4 μm or less.

  When the holding unit 15 is disposed so as not to face the detector 6 as in the present embodiment, any material may be used as long as it is a conductive metal. The cover 14 is preferably grounded.

  If a large amount of insulating material adheres to the cover 14 itself, the electron orbit shifts due to the charging of the insulating material attached to the cover 14, and the detection accuracy of the position of the mark 9 may be lowered. Therefore, the drawing apparatus 1 has a mechanism capable of replacing the cover 14.

  The replacement mechanism of the cover 14 will be described with reference to FIG. FIG. 3 is a view of the exchange table 11 as seen from above. FIG. 3 (a) shows the structure of the exchange base 11, and includes a claw 23a for pushing out the used cover 14a to which the insulating material adheres, a storage place 24a for the used cover 14a, and a claw 23b for inserting a new cover 14b. And a storage place 24b for a new cover 14b. The used cover 14a and the new cover 14b have the same configuration as the cover 14 described above.

  FIG. 3B is a diagram of the exchange table 11 before the exchange work is started, and a new cover 14b is placed thereon. In this state, the exchange table 11 and the stage 7 are carried into the vacuum chamber 20 through the load lock chamber 22. FIG. 3C is a diagram of the exchange base 11 after the used cover 14a placed on the detector 6 is removed. FIG. 3D is a diagram of the exchange base 11 after the new cover 14 a is mounted on the holder 13. The used cover 14 a is collected outside the atmosphere chamber 21 and the drawing apparatus 1 through the load lock chamber 22.

  4A to 4D show a process of removing the used cover 14a using the exchange base 11, and FIGS. 4E to 4F show a process of attaching a new cover 14a using the exchange base 11. Show. In FIG. 4A, the control unit 12 moves the stage 7 so that the storage place 24 a of the exchange table 11 is below the lens barrel 2. Further, the stage 7 is raised so that the claw 23a is flush with the cover 14a. 4B to 4C show a process of moving the stage 7 in the horizontal direction and removing the used cover 14a. In FIG. 4D, the used cover 14a is placed in the storage place 24a. The mounted state is shown.

  Next, the control unit 12 moves the stage 7 so that the new cover 14 b is positioned beside the holder 13. FIGS. 4E to 4G show a state in which the stage 7 is moved in the horizontal direction, and the new cover 14b is attached to the holder 13 while being pushed by the claws 23b. FIG. 4 (h) shows a state where the mounting is finished and the stage 7 is lowered.

  This completes the description of the method for replacing the cover 14. The replacement method is not limited to this embodiment, and other methods may be used as long as the exposed portion of the thin film 16 on the irradiated object side can be replaced without releasing the inside of the vacuum chamber 20 to the atmosphere.

  As described above, in this embodiment, the cover 14 is disposed both when the detector 6 is used and when it is not used, so that the adhesion rate of the insulating material to the detector 6 can be reduced. Further, since the mechanism can exchange only the cover 14 without releasing the atmosphere of the vacuum chamber 20, the baseline is determined by reducing the operating time loss due to the opening of the atmosphere and measuring the position of the mark 9. Work can be performed accurately over a long period of time.

[Second Embodiment]
A second embodiment of the cover 14 is shown in FIG. A support portion 18 that supports the thin wire 17 and the center of the thin film 16 is provided using the same or similar material as the holding portion 15. The thin line 17 is not limited to a cross structure, and may be a mesh structure. This makes it possible to easily hold the plane near the center of the thin film 16 shown in FIG. When members for supporting the thin film, such as the thin wires 17 and the support portion 18, are arranged facing the detector 6, these members are preferably light metals that do not interfere with detection of reflected electrons.

[Third Embodiment]
A third embodiment of the cover 14 is shown in FIG. FIG. 6A shows a form in which two thin films 16 are supported by one holding portion 15. When a predetermined amount or more of the insulating material adheres to one thin film 16, the new thin film 16 is brought to the front of the detector 6 at a position facing the detector 6 by horizontally shifting on the holder 13 using the claw 23 a of the exchange table 11. Can be arranged.

  FIG. 6B shows a form in which six thin films 16 are held by one disk-shaped holding portion 13. The cover 14 is held by a holder mechanism (not shown) that can hold a circular member different from the holder 13 shown in FIG. A new thin film 16 can be disposed on the front surface of the detector 6 by rotating the cover 14 using a gear mechanism or a hand (not shown).

  In the present embodiment, since one cover 14 has a plurality of thin films 16, even if a predetermined amount or more of an insulating material adheres to one thin film 16, the cover 14 is immediately carried out of the vacuum chamber 20. There is an advantage that it is not necessary.

[Fourth Embodiment]
A fourth embodiment of the cover 14 is shown in FIG. The cover 14 in this embodiment has a structure in which a conductive disc 30 (a plate having openings) having four openings 19 is overlapped in addition to the thin film 16 and the holding portion 15 similar to those in the first embodiment. doing. FIG.7 (b) has shown sectional drawing of AA 'in Fig.7 (a). When detecting the reflected electrons, the electrons passing through the opening 19 of the disk 30 and passing through the thin film 16 below the opening 19 reach the detection layer of the detector 6.

  In the case of the present embodiment, since the number of electrons that reach is smaller than in the other embodiments described above, detection is performed by increasing the amplification factor of the detector 6. When the cover 14 is used for a predetermined time at the position of the same opening 19, the position of the opening 19 with respect to the thin film 16 is changed by rotating the disk 30 using a hand (not shown) or the like. Thereby, the exposed portion of the thin film 16 on the irradiated object side can be exchanged. With such a configuration, the same cover 14 can be used until all the surfaces of the thin film 16 are contaminated by the insulating material while gradually shifting the position of the opening 19 of the disk 30. Therefore, it is possible to use the same cover 14 for a long period of time compared to the first embodiment.

[Fifth Embodiment]
A fifth embodiment of the cover 14 is shown in FIG. The fifth embodiment is different from the other embodiments in that an uneven structure is formed on the surface of the holding portion 15 facing the resist 8 (sample side). FIG. 8A shows a case where a concavo-convex structure is formed on the cover 14 of the first embodiment, and FIG. 8B shows a case where a concavo-convex structure is formed on the surface of the disc 30 of the fourth embodiment. . These uneven structures are formed by dry etching or machining. The depth of the concavo-convex structure is, for example, not less than 0.1 mm and not more than half of the thickness of the holding part 15, more preferably not less than 0.5 mm and not more than half of the thickness of the holding part 15. The pitch of the concavo-convex structure is preferably 1/2 or less of the depth.

  It is known that when the concavo-convex structure is formed, most of the insulating material adheres to the concave portions and only slightly adheres to the convex portions. Therefore, even if electric charges are accumulated in the concave portion of the holding portion 15 or the disc 30, the convex portion side that is substantially the surface of the holding portion 15 or the disc 30 can be regarded as no potential. Thereby, it is possible to prevent the trajectory of the electron beam irradiated when drawing the pattern from being shifted due to the charges accumulated in the holding unit 15 or the disk 30.

  Therefore, although the holding portion 15 and the disc 30 are conductive, it is preferable to adopt such a configuration when the accumulation of charges due to the adhesion of the insulating material is a concern. In particular, as shown in FIGS. 5 and 8B, when the holding unit 15 or the disc 30 is arranged so as to overlap the detector 6, the present embodiment is applied to the resist 8 side of the holding unit 15. It is preferable to prevent charges from being accumulated near the center of the detector 6. As a result, the allowable value of the amount of the insulating material attached to the cover 14 can be increased, and the effect of reducing the number of replacements of the cover 14 can be obtained.

[Judgment method of cover replacement time]
(First judgment method)
The replacement time of the cover 14 can be determined from the usage period of the drawing apparatus 1, the total irradiation energy amount for the wafer 4, and the like. However, since the amount of insulating material and the amount of insulating material attached vary depending on the amount of electron beam current, acceleration voltage, resist type, resist film thickness, pattern structure formed on the wafer 4, and the like, The deposition rate of the insulating material is not constant. Therefore, it is preferable that the replacement time of the cover 14 can be determined based on the measurement result.

A first determination method for determining whether or not the adhesion amount of the insulating material to the thin film 16 of the cover 14 has reached a predetermined amount will be described with reference to FIG. A detector 6 photodiode is used and is grounded with respect to the potential reference point. There are ammeter (second instrument) 25a for detecting the current I ₁ generated by the photodiode detector 6. On the other hand, a cover 14 having a thin film 16 is also connected to ground with respect to the potential reference point, ammeter 25b (first measuring device for detecting a current (current flowing between the ground plane and the cover) I ₂ flowing through the ground wiring )

The control unit 26 (determination unit) is connected to the ammeters 25a and 25b and instructs them to measure, or determines the replacement time of the cover 14 from the value of the current value. In the following measurement method, since most of the area of the cover 14 is the thin film 16, it is considered that the change in the current I ₂ is caused by the state change of the thin film 16.

The currents I ₁ and I ₂ change depending on the charges accumulated on the surface of the thin film 16 and the charges accumulated in the detector 6. The current I ₁ is represented by the formula (1), and the current formula I ₂ is represented by the formula (2).

In Equation (1), E ₁ is the energy of the electron beam that has passed through the cover 14 and entered the detector 6, E ₂ is the energy of the reflected electrons that have entered the detector 6, and E ₃ is incident on the detector 6. The energy of secondary electrons generated by reflected electrons is shown. n _e ′ (E _n ) (n = 1, 2, 3) indicates the number of electrons having each energy En. C ₁ is a detection sensitivity of the detector 6, C ₂ is a reflected electron coefficient (a coefficient depending on the atomic number of the cover 14), and C ₃ is a secondary electron emission coefficient by the detector 6.

  The first term in the curly brackets [] indicates the total energy of electrons that are reflected in the wafer 4, pass through the cover 14, and enter the detector 6. The second term indicates the total energy resulting from the reflected electrons that have been reflected again on the detector 6 among the reflected electrons that have reached the detector 6. The third term represents the total energy with which secondary electrons generated in the detector 6 by the reflected electrons that have reached the detector 6 are emitted to the outside.

  Here, in Expression (1), the current ratio of each term is 1st term: 2nd term: 3rd term = 1: 0.11: 0.0006. When the energy of electrons incident on the wafer 4 is 100 keV, the energy of reflected electrons is about 70 keV, and the energy of secondary electrons is about 5 keV. Even if an insulating material adheres to the surface of the detector 6, the reflected electrons generated again in the detector 6 have a large energy and are transmitted through the insulating material and emitted to the outside.

On the other hand, the secondary electrons shown in the third term cannot pass through the insulating material because of their low energy. Therefore the value that varies with the deposition of insulating material is only the value of the third term, the contribution to be change in the current value I ₁ as has decreased the amount of emission of secondary electrons from the ratio of the previous sections ignore As small as possible.

On the other hand, in Expression (2), the first term represents the amount of current of electrons absorbed in the cover 14 among the electrons that are reflected electrons from the wafer 4 and incident on the cover 14. Here, the number and energy of secondary electrons emitted from the wafer 4 are negligible and neglected because the energy is small. The second term indicates the amount of secondary electrons emitted from the cover 14 among the electrons incident on the cover 14. Since there is no amplifying effect in the cover 14, the number of reflected electrons are absorbed and secondary electron number directly, is detected as the current I _2.

n _e (E ₁ ) indicates the number of reflected electrons corresponding to the energy E ₁ of the reflected electrons. μ _e is the absorption rate of electrons by the cover 14 (= number of absorbed electrons / number of incident electrons). For example, when the thin film 16 is Al having a thickness of 1 μm, μe is about 0.1%. C ₂ ′ is a secondary electron emission rate (= secondary electron number / incident electron number) by the cover 14 and is about 11%. Here, the absorption rate of the reflected electrons does not change even when the insulating material attached to the surface increases, but the emission rate of secondary electrons changes due to the influence of the insulating material because the energy of the secondary electrons is small. Therefore changes in the current I ₂ flowing to the cover 14 mainly depends on the change of the second term. Cover 14 current I ₂ so as to compensate for the secondary electrons flow emitted from, the value of the current I ₂ for the amount of emitted secondary electrons decreases with an insulating material is increased to adhere to the surface of the thin film 16 is Decrease.

FIG. 9B shows the value of the change in current with respect to the amount of insulating material attached to the surface of the cover 14 expressed by the equations (1) and (2). For the above-described reason, only the current I ₂ decreases according to the amount of the insulating material deposited. Therefore, the cover 14 should be replaced when the predetermined current value I ₀ is reached by setting a threshold value for the current value. The control unit 26 determines.

FIG. 10 shows a flowchart of the cover replacement timing determination method of the present embodiment. This method is capable of always performed during rendering, begin drawing on the wafer 4 (S101) starts measuring the current I ₂ after (S102) to. Current I ₂ is determined by the control unit 26 whether has reached a predetermined value (S103), when it is determined to have reached (YES) to determine whether separated drawing operation is good (S104).

  For example, whether or not drawing on one wafer 4 or drawing on a wafer of the same lot is finished. When the control unit 26 determines that the separation is good (YES), the control unit 12 moves the stage 7 and replaces the cover 14 by the method described above.

Note that the current value need not always be measured, and may be measured at every well-separated timing. Further, the determination may be made not based on whether or not the current I ₂ has reached a predetermined value but whether or not the value of I ₂ / I ₁ has reached a predetermined value. In the case of determination based on the ratio, determination can be made using the same predetermined value regardless of the signal amplification factor of the detector 6.

  According to the above method, it is possible to appropriately determine the amount of the insulating material attached to the thin film 16, and it is possible to replace the cover 14 every time a predetermined amount of the insulating material is attached. Thereby, the orbit shift | offset | difference of the electron beam in drawing resulting from the insulating substance adhering to the circumference | surroundings of the detector 6 can be suppressed.

(Second determination method)
The second determination method for the replacement time of the cover 14 is a method of measuring the amount of change in I ₂ with higher accuracy. This is shown in FIG. First determination method and the cover 14 is grounded, are arranged and ammeter 25b for detecting a current I ₂ flowing through the ground line, a further variable power supply 27b. Also it has grounded the reference table 10, are arranged and ammeter 25c for detecting a current I ₃ flowing through the ground line, the variable power supply 27c.

  In the second determination method, the influence of the secondary electrons emitted from the wafer 4 ignored in the first determination method described above, and the secondary electrons emitted from the cover 14 return to the cover 14 again. The effect of secondary electrons can be made. These are phenomena that occur due to the influence of the potential of the space between the secondary electrons having low energy and the cover 14. Therefore, by reducing the influence of the space potential, secondary electrons emitted from the cover 14 can be measured with higher accuracy, and the degree of adhesion of the insulating material to the cover 14 can be determined. Since this determination method involves a potential operation, it is preferable to perform the mark 9 as an irradiation target without performing the drawing.

When reflected electrons and secondary electrons (e _c ) are emitted from the mark 9 or the secondary electrons return to the mark 9 again, I ₃ changes by the amount corresponding to the change in the number of secondary electrons. A positive voltage is gradually applied using the variable power source 27c to change the surrounding potential. As a result, the secondary electrons gradually emitted do not go to the cover 14, so that the value of the current I 3 converges to a predetermined value, and only the reflected electrons are incident on the cover 14. At this time, the potential change by the variable power source 27c is finished.

On the other hand, the surrounding potential is changed by gradually applying a negative voltage using the variable power source 27b. This prevents secondary electrons (e _b ) emitted from the cover 14 from returning to the cover 14 again. Variable power supply 27b to a current value I ₂ to be measured becomes a predetermined value after changing the potential, measuring the current I ₂ while subtracting the converged I ₂ as an offset. The measured value can be expressed by Expression (2) in consideration of only the influence of the reflected electrons incident on the cover 14 without being influenced by the secondary electrons ignored in Expression (2).

By performing such a potential operation using the variable power sources 27b and 27c, the currents I ₁ and I ₂ measured by the ammeters 25a and 25b are accurately expressed by the same formula as described above. Therefore, the change in current I _2, more precisely the control unit 26 than the first determination method it is possible to determine the replacement timing of the cover 14.

[Other Embodiments]
Although an electron beam drawing apparatus has been described as an example, the present invention is not limited to an electron having energy of 30 keV or more, such as a scanning electron microscope or a transmission electron microscope capable of acquiring a reflected electron image reflecting composition information. It is possible to apply to an apparatus having a detector to detect. Moreover, the replacement time of the cover 14 may not be the above-described determination method. For example, the replacement time may be set every time a predetermined number of wafers are processed, every predetermined drawing time, every predetermined energy irradiation, every predetermined operation time, or the like.

[How to determine the baseline]
FIG. 12 shows a method for determining the above-mentioned baseline in drawing of an electron beam according to each embodiment. First, the control unit 12 moves the stage 7 so that the reference table 10 is positioned below the electron beam optical system 5. Thereafter, the mark 9 is irradiated with an electron beam (S201), and the reflected electrons from the mark 9 are measured through the cover 14, thereby detecting the position of the mark 9. The optical axis position of the electron optical system 5 is obtained from the position of the mark 9 (S202). Similarly, the control unit 12 moves the stage 7 so that the reference table 10 is positioned below the optical sensor. The optical sensor 28 irradiates the mark 9 with light (203), and obtains the optical axis position from the position of the mark 9 (S204). From the measurement results of S202 and S204, a baseline that is the distance between both axes is determined (S205).

  When the drawing apparatus 1 does not have the optical sensor 28, there is no need to obtain a baseline. Instead, the position of an alignment mark (not shown) formed on the wafer 4 is measured by irradiating an electron beam. The position of the alignment mark may be obtained by detecting reflected electrons by the detector 6.

  The irradiated object according to the present invention is a mark or the like used for determining the baseline in each of the above-described embodiments, but is not limited to this, and is an object irradiated with an electron beam while performing reflected electron detection. Means that.

[Product Manufacturing Method]
In the manufacturing method of the article (semiconductor integrated circuit element, liquid crystal display element, CD-RW, photomask, etc.) of the present invention, a pattern is exposed on a substrate (wafer, glass plate, etc.) using the stage apparatus of the above-described embodiment. A lithographic step of developing, and a step of developing the exposed substrate. Furthermore, other known processing steps (oxidation, film formation, vapor deposition, etching, ion implantation, planarization, resist peeling, dicing, bonding, packaging, etc.) may be included.

DESCRIPTION OF SYMBOLS 1 Drawing apparatus 4 Wafer 5 Electro-optical system 9 Mark 10 Reference stand 14 Cover 15 Holding part 16 Thin film 25a, 25b Ammeter 26 Control part 30 Disc

Claims (17)

A detector for detecting electrons emitted from the irradiated object by electron beam irradiation;
A cover having a metal film between the detector and the irradiated object;
The detector detects an electron transmitted through the metal film, and the electron beam irradiation apparatus.   The irradiation apparatus according to claim 1, wherein an exposed portion of the metal film with respect to the irradiation object side is replaceable.   The irradiation apparatus according to claim 1, wherein the metal film covers a surface of the detector.   The irradiation apparatus according to claim 1, wherein the metal film has an electron transmittance of 5% or more.   The irradiation apparatus according to claim 1, wherein the metal film contains aluminum or nickel.   6. The irradiation apparatus according to claim 1, wherein a thickness of the metal film is 0.5 μm or more and 25 μm or less.   The irradiation apparatus according to claim 1, wherein the metal film has a thickness of 2 μm or more and 14 μm or less.   The irradiation according to claim 1, wherein the cover has a support member that supports the metal film, and the support member has an uneven structure on a surface on the irradiated object side. apparatus.   The said cover has a board which has an opening between the said metal film and the said to-be-irradiated object, The said board has a concavo-convex structure in the surface at the side of an to-be-irradiated object. The irradiation apparatus of Claim 1. A measuring instrument for measuring a current flowing between the ground plane and the cover;
The irradiation apparatus according to claim 1, further comprising a determination unit that determines a replacement time of the metal film based on a measurement value of the measuring instrument. The measuring instrument for measuring the current flowing between the ground plane and the cover is a first measuring instrument,
A second measuring instrument for measuring the current generated in the detector;
The irradiation device according to claim 10, wherein the determination unit determines a replacement time of the metal film based on measurement values obtained by the first measuring instrument and the second measuring instrument.   The electron beam irradiation apparatus according to claim 11, wherein the electrons are reflected electrons. A method for detecting the position of a mark on a moving body in a lithography process in which a pattern is formed by irradiating an electron beam on a substrate,
Irradiating an electron beam toward the mark;
Detecting the electrons reflected by the mark by irradiation of the electron beam and passing through the metal film;
Obtaining the position of the mark based on the result of the detection, and a method for detecting the position of the mark.   The mark position detection method according to claim 13, wherein the metal film has an electron transmittance of 5% or more.   15. The mark position detection method according to claim 12, wherein the metal film contains aluminum or nickel. A step of measuring a current flowing between a cover having a metal film and a ground plane, which is disposed between a detector for detecting electrons emitted from the irradiated object by electron beam irradiation and the irradiated object;
And determining the replacement time of the metal film based on the measured value obtained by the measurement. Irradiating an electron beam using the irradiation apparatus according to any one of claims 1 to 12, and drawing a pattern on a substrate;
And a step of developing the substrate.

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