JP2015149449A - charged particle beam lithography system, contaminant removal method, and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam lithography system capable of removing contaminants adhering to an optical member in the system, while minimizing deterioration of drawing quality.SOLUTION: A charged particle beam lithography system for drawing a pattern on a substrate by using a charged particle beam having an illuminance distribution is provided. The system has an irradiated member that is irradiated with a charged particle beam, and an adjustment section for adjusting the illuminance distribution of the charged particle beam. On the irradiated member that is irradiated with a charged particle beam, a low illuminance area where the illuminance of the charged particle beam is lower than a predetermined value appears, and contaminants adhere to the illuminance area on the irradiated member. The adjustment section adjusts the illuminance distribution of the charged particle beam so as to remove the contaminants adhering to the irradiated member.

Description

  The present invention relates to a charged particle beam drawing apparatus, a contaminant removal method, and a device manufacturing method.

  Patent Document 1 discloses a technique for cleaning contaminants adhering to an optical element in an apparatus by introducing an oxidizing gas in an exposure apparatus. In Patent Document 1, water vapor and oxygen gas are introduced into an exposure apparatus, and an object is irradiated with an energy beam to clean contaminants. Oxygen is supplied to places where the illuminance of the energy beam is low, and water vapor is supplied to places where the illuminance of the energy beam is high.

JP 2011-171620 A

  In the prior art, there is a problem that contamination (contamination) cannot be suppressed in a region where the illuminance of the energy beam is small. In the technique of Patent Document 1, the removal rate decreases in a region where the illuminance of the energy beam is small, and thus contaminants adhere. In particular, when water vapor is introduced, the removal rate is greatly reduced in a region where the illuminance of the energy beam is small. When this deposit is irradiated with an energy beam, the deposit is charged and has a potential. With this potential, energy beams using charged particles in particular change from the designed state of the electric field distribution of the beam path, and affect the trajectory of the energy beam. This influence causes a problem that the beam position exposed on the substrate is shifted, and the drawing quality is deteriorated.

  An object of the present invention is to provide a charged particle beam drawing apparatus capable of effectively removing contaminants attached to an optical member in the apparatus while suppressing a reduction in drawing quality.

  According to one aspect of the present invention, a charged particle beam drawing apparatus for drawing a substrate held by a substrate stage using a charged particle beam, the charged particle source emitting a charged particle beam, and the charged particle source And an aperture provided between the substrate stage and a cleaning mode for removing contaminants attached to the aperture, the illuminance of the charged particle beam to the peripheral edge of the aperture of the aperture is increased more than when drawing on the substrate. There is provided a charged particle beam drawing apparatus characterized by having an adjusting unit to be operated.

  ADVANTAGE OF THE INVENTION According to this invention, the contaminant which adhered to the optical member in an apparatus can be removed effectively, suppressing the fall of drawing quality.

The block diagram of the charged particle beam drawing apparatus in embodiment. The figure explaining the adhesion deposition of a contaminant. The figure which shows the example using the electrostatic lens for washing | cleaning. The figure which shows the difference in illumination intensity distribution at the time of normal drawing and at the time of washing | cleaning. The figure explaining the example using a deflection electrode. The figure which shows the example of arrangement | positioning of a deflection electrode. The figure which shows the example of the deflection | deviation electrode on an array. The figure explaining the difference in illumination intensity distribution at the time of normal drawing and at the time of washing | cleaning. The figure which shows the example of a method to change an electron beam irradiation state.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, but merely shows specific examples advantageous for the implementation of the present invention. Moreover, not all combinations of features described in the following embodiments are indispensable for solving the problems of the present invention. In addition, in each figure, about the same member, the same reference number is attached | subjected and the overlapping description is abbreviate | omitted.

<First Embodiment>
FIG. 1 is a configuration diagram of a charged particle beam drawing apparatus according to the first embodiment. In the figure, an electron gun 1 as a charged particle source emits a charged particle beam to form a crossover image 10. The electron beam 3 emanating from the crossover image 10 becomes a parallel beam by the action of the collimator lens 11 and enters the first aperture array 34 as an optical member constituting the electron beam optical system. The first aperture array 34 has a plurality of circular openings for allowing a part of the charged particle beam to pass therethrough, and the incident electrons are divided into a plurality of electron beams having a diameter of about 0.1 mm to 2 mm, for example. The electron beam that has passed through the first aperture array 34 is incident on the second aperture array 35 having a plurality of circular openings arranged in a matrix, and is finer, for example, about 0.001 mm to 0.05 mm in diameter. Is divided into a plurality of electron beams. The reason why the electron beam is divided in two stages as described above is that a large number of electron beams divided over as large an area as possible are used, so that fine adjustment of the irradiation position of each electron beam and reduction of aberration at the time of focusing are reduced. This is because a large number of electron beams are controlled in groups. For example, 300,000 electron beams are divided into 1000 groups of 300 (illustrated as 5 in FIG. 1) and controlled by an electron optical system of 1000 groups (illustrated as 3 groups in FIG. 1).

  The electron beam that has passed through the second aperture array 35 is an electrostatic lens composed of three electrode plates having a circular opening (in the figure, three are integrally shown in a lens shape). Incident on the array 12. A stopping aperture array 15 in which small apertures are arranged in a matrix is disposed at a position where an electron beam that has passed through the electrostatic lens array 12 first forms a crossover. The blanking operation by the stopping aperture array 15 is executed by the blanker array 14. The electron beam that has passed through the stopping aperture array 15 is imaged by the second electrostatic lens array 13 and forms an image of the original crossover image 10 on a substrate such as a wafer or a mask. During pattern drawing, the substrate 17 held by the substrate stage 18 continuously moves in the X direction. Then, an image on the surface of the substrate 17 is deflected in the Y direction by the deflector 16 and blanked by the blanker array 14 based on the measurement result in real time by a laser length measuring machine (not shown).

  By the above operation, a desired latent image can be formed on the resist. These components are arranged inside the container 20. Moreover, the charged particle beam drawing apparatus includes an evacuation unit such as a vacuum pump, and can evacuate through the exhaust port 19 to form a vacuum environment (for example, a pressure of 1E-5 Pa or less) inside the container 20. Yes. In particular, since the electron lens unit requires a high degree of vacuum, an exhaust system may be provided separately from the substrate stage unit that generates a large amount of gas.

  In such a charged particle beam drawing apparatus, there is a possibility that contaminants may adhere to the aperture arrays 34 and 35 that are irradiated members to which the charged particle beam is irradiated. Examples of such contaminants include carbon, which are caused by an outgas released from members constituting the charged particle beam drawing apparatus and a carbon compound released from a resist (photosensitive agent) applied to the substrate. This contaminant is positively or negatively charged when irradiated with the electron beam 3, or secondary electrons or reflected electrons generated by the electron beam 3. If it does so, attraction or repulsion will be given to the electron of the electron beam 3, and there exists a possibility that the electron of the electron beam 3 may remove | deviate from a desired orbit. A vacuum environment is formed inside the container 20, but hydrogen and water vapor remain. It is known that the adhesion of carbon-based contaminants can be suppressed by irradiation with an electron beam in an atmosphere where water vapor exists. In particular, since the first aperture array 34 is far from the resist, the influence of the carbon compound derived from the resist is small. However, since the first aperture array 34 is close to the electron gun 1, the electron beam 3 with high illuminance is irradiated. In the place where the illuminance of the electron beam is high, the effect of suppressing water vapor is large. However, this suppression capability depends on the partial pressure of water vapor and the illuminance of the electron beam, and the attachment of contaminants proceeds where the illuminance of the electron beam is small.

  FIG. 2 shows an example of the contaminant 6 deposited and deposited. A low illuminance region in which the illuminance of the electron beam is lower than a predetermined value is generated on the irradiated member irradiated with the electron beam. For example, in FIG. 2, the illuminance of the electron beam decreases toward the outside of the irradiation region at the portion corresponding to the edge of the electron beam irradiation region of each of the first and second aperture arrays. This portion is located at the peripheral edge of the opening so as to surround each of the plurality of openings in each aperture. In the peripheral portion of the opening, since contaminants are likely to adhere to the portion where the illuminance of the electron beam is low as described above, contaminants 6 accumulate as shown in the figure.

  In the present embodiment, the charged particle beam drawing apparatus includes a cleaning electrostatic lens array 9 as an adjustment unit. The charged particle beam drawing apparatus changes the irradiation state of the electron beam 3 by the cleaning electrostatic lens array 9 at the time of cleaning in a cleaning mode for removing contaminants attached to the aperture. As a result, the illuminance distribution of the electron beam on the second aperture array 35 is expanded, and the illuminance of the portion that was low illuminance at the time of drawing is increased. Therefore, the illuminance of the charged particle beam at the contaminated portion is higher after the adjustment than before the adjustment by the adjustment unit. As a result, it is possible to remove the contaminants by reacting the water vapor with the contaminants.

  Hereinafter, the configuration and function of each part in the cleaning electrostatic lens array 9 will be described with reference to an operation method during cleaning as an example.

  During drawing, the electrostatic lens array 9 for cleaning is controlled by the computer 4 so as not to exhibit an action as a lens. FIG. 3 is an enlarged view of a main part of the electron optical system in FIG. The cleaning electrostatic lens array 9 includes three electrode plates having circular openings, a first electrostatic lens electrode 30, a second electrostatic lens electrode 31, and a third electrostatic lens electrode 32. . At the time of drawing on a normal substrate, the three electrostatic lens electrodes for cleaning are all controlled to the ground potential by the computer 4. Therefore, nothing acts on the electron beam 5 as shown in FIG.

  On the other hand, in the cleaning mode for removing contaminants attached to the aperture, the first electrostatic lens electrode 30 and the third electrostatic lens electrode 32 are set to the ground potential and the second electrostatic lens electrode 31 is set before starting the cleaning. A negative potential is applied to. At this time, a potential may be applied to the cleaning electrostatic lens array 9 while irradiating the electron beam 5. After a negative potential is applied to the second electrostatic lens electrode 31, the electron beam 5 that has passed through the cleaning electrostatic lens array 9 crosses over between the cleaning electrostatic lens array 9 and the second aperture array 35. Is formed. Then, as shown in FIG. 3, the electron beam 5 is irradiated on a region wider than the time of drawing on the second aperture array 35. Control of the cleaning electrostatic lens array 9 at the time of drawing and cleaning is performed according to a sequence prepared in advance by the computer 4.

  FIG. 4 is a diagram schematically showing how the illuminance distribution of the electron beam 5 changes on the second aperture array 35 with and without using the cleaning electrostatic lens array 9. By using the electrostatic lens array 9 for cleaning, the illuminance of the portion where the illuminance is low at the time of normal drawing increases. By irradiating the high-illuminance electron beam to the contaminant 6 attached to the low-illuminance portion, the contaminant 6 can be removed by reacting the water vapor with the contaminant 6.

  The gas introduction unit 8 to be introduced illustrated in FIG. 1 is used when gas is actively introduced into the aperture arrays 34 and 35. Here, the gas may be a gas selected from water vapor, oxygen, and ozone (including a mixed gas obtained by mixing these gases). By introducing the oxidizing gas from the gas introduction part 8 at the time of cleaning, the concentration of the oxidizing gas in the vicinity of the contaminant is increased and the removal rate can be increased. As a result, since the cleaning time is shortened, the downtime of the drawing apparatus can be reduced. The oxidizing gas to be introduced is introduced so that the pressure in the vicinity of the cleaning electrostatic lens array 9 is 0.001 Pa or less. This is to prevent discharge from occurring between the electrodes in the cleaning electrostatic lens. The timing of introducing the oxidizing gas is before applying a potential to the cleaning electrostatic lens array 9. This is also for preventing a large amount of gas from being erroneously introduced and causing discharge between the electrodes in the electrostatic cleaning lens.

  Whether or not the removal of the contaminant 6 has been completed is determined by measuring the irradiation state of the electron beam with an electron beam measuring device (not shown) installed on the substrate stage 18 and confirming whether the desired optical characteristics have been restored. It is done by doing. Alternatively, it may be determined that the sequence has been removed when the preset sequence is completed. The second electrostatic lens electrode 31 is set to the ground potential to finish the cleaning.

According to the present embodiment, by changing the irradiation intensity distribution state of the electron beam, it is possible to irradiate the portion where the contaminant is attached with an electron beam with higher illuminance than usual. As a result, the contaminants react with the oxidizing gas (water vapor or oxygen) in the atmosphere, and the contaminants 6 attached to the aperture can be efficiently removed. Therefore, the life of the drawing apparatus can be extended.
In the present embodiment, the aperture array is exemplified as the irradiated member that irradiates the electron beam. However, the aperture array is not limited to this, and may include a shielding member that does not have an opening, an absorbing member, a reflecting member, and the like.

Second Embodiment
FIG. 5 is a schematic view showing a part of the electron optical system of the charged particle beam drawing apparatus according to the second embodiment. Parts having the same configuration and the same function as those of the first embodiment are denoted by the same reference numerals in the drawing, and the description thereof is omitted.

  The present embodiment differs from the first embodiment in that the deflecting electrodes 22 and 23 are used to deflect the trajectory of the electron beam and irradiate the contaminant 6 on the aperture array 34 with the high-illuminance electron beam. Is different.

  Hereinafter, an example of an operation method at the time of cleaning will be described regarding the configuration and function of each part in the deflection electrodes 22 and 23.

  The deflection electrodes 22 and 23 are controlled by the computer 4 and a potential is applied in a sequence prepared in advance. During drawing, the deflection electrodes 22 and 23 are controlled by the computer 4 so as to have the same potential, and the deflection electrodes 22 and 23 do not act on the electron beam.

  Before starting cleaning, the computer 4 controls to apply a potential so that a potential difference is generated between the deflection electrodes 22 and 23. The electron beam 5 is incident on the aperture array 34 with a potential applied to the deflection electrodes 22 and 23. The electron beam 5 that has passed between the deflection electrodes 22 and 23 is deflected in one direction as shown in the figure. Thereby, the contaminant 6 on the aperture array 34 is irradiated with an illuminance greater than that at the time of drawing, and the contaminant can be removed.

  Further, by reversing the applied voltage of the deflection electrodes 22 and 23 to deflect the electron beam 5 in the reverse direction, the opposite contaminant 6 can be irradiated with the electron beam, and the contaminant can be removed. Furthermore, by installing a deflection electrode (not shown) that faces the paper surface direction and deflecting the electron beam 5 in the paper surface direction, the contaminants 6 in the normal irradiation region can be removed.

  FIG. 6 shows an example of the arrangement of the deflection electrodes as viewed from the traveling direction of the electron beam 5. A plurality of electron beams 5 divided by the first aperture array 34 are deflected in one direction by the deflection electrodes 22 and 23 and deflected by using the deflection electrodes 24 and 25 in a direction perpendicular to the deflection electrodes 22 and 23. The deflection direction of the electron beam 5 can be freely controlled.

  FIG. 7 shows an example of the deflection electrode substrate 7 having a numerical aperture corresponding to each of the electron beams 5 divided by the first aperture array 34. For example, the deflection electrode substrate 7 is disposed between the first aperture array 34 and the second aperture array 35, and a deflection electrode is formed on each of the arrayed electron beams 5. FIG. 7 shows the deflection electrode substrate 7 viewed from the traveling direction of the electron beam. The deflection electrodes 22, 23 and 24, 25 facing each other across the opening 33 through which the electron beam 5 passes are arranged so as to be orthogonal to each other. By adjusting the potential applied to these two pairs of opposing deflection electrodes, the deflection direction of the electron beam can be controlled by 360 degrees. As a result, the contaminants deposited on the irradiation areas の of the respective electron beams 5 on the second aperture array 35, that is, the opening peripheral edge of the aperture can be sequentially removed. As a result, the contaminants on the second aperture array 35 can be thoroughly cleaned. With such an arrangement, it is possible to deflect the electron beam 5 closer to the electron beam 5, and it is possible to irradiate the contaminated material with an electron beam with high illuminance more reliably.

  FIG. 8 schematically shows how the illuminance distribution of the electron beam 5 is shifted when a voltage is applied to the deflection electrode and when it is not applied. By applying the deflection, the illuminance of the portion where the illuminance is low at the time of normal drawing increases. As a result, by irradiating the contaminant attached to the low illuminance portion with a high illuminance electron beam, the contaminant can be removed by reacting the water vapor with the contaminant.

  The amount by which the electron beam 5 is deflected, that is, how much the irradiation position of the electron beam 5 is shifted on the second aperture array 35 (the difference between the practice and the dotted line in FIG. 8) can be determined by the following parameters. For example, the distance between the accelerated voltage of the electron beam 5 and the deflection electrode, the potential difference between the deflection electrodes, the length of the deflection electrode in the electron beam traveling direction, the distance between the deflection electrode and the second aperture array 35, and the like.

  In the present embodiment, the deflection electrodes 22 to 25 are disposed between the first aperture array 34 and the second aperture array 35, but may be disposed between the first aperture array 34 and the collimator lens 11. Good. By doing so, both the contamination of the first aperture array 34 and the contamination of the second aperture can be removed simultaneously.

  Whether or not the removal of the pollutant has been completed is determined by measuring the irradiation state of the electron beam with an electron beam measuring device (not shown) installed on the substrate stage 18 and confirming whether the desired optical characteristics are restored. Is done. Alternatively, it may be determined that the sequence has been removed when the preset sequence is completed. The deflection electrodes 22 and 23 are set to the same potential to eliminate the deflection of the electron beam 5, and the cleaning is completed.

  According to the present embodiment, since contaminants attached to the aperture can be efficiently removed, the life of the drawing apparatus can be extended.

<Third Embodiment>
FIG. 9 shows an example of a method for changing the electron beam irradiation state on the first aperture array 34. In the present embodiment, the illuminance distribution of the electron beam 3 is changed using the collimator lens 11. As described above, the electron lens is composed of three parallel electrodes having openings. In FIG. 9, the collimator lens 11 includes a collimator electrostatic lens first electrode 36, a collimator electrostatic lens second electrode 37, and a collimator. An electrostatic lens third electrode 38 is included. By applying a negative electric potential to the collimator electrostatic lens second electrode 37 in the middle of the three electrodes, the electron beam 3 acts as a convex lens, and the diverging electron beam 3 is usually converted into a parallel beam. Yes. In this example, the electron beam 3 irradiated to the first aperture array 34 by changing the power of the lens by adjusting the potential applied to the collimator electrostatic lens second electrode 37 of the collimator lens 11 is shown in FIG. Thus, the illuminance distribution can be expanded. By doing so, the illuminance of the electron beam 3 irradiated to the contaminant 6 deposited on the irradiation area 淵 of the electron beam 3 on the first aperture array 34, for example, the peripheral edge of the opening, is made higher than usual, and contamination is caused. Object 6 can be removed.
As described above, a contaminant removal method is considered as one aspect of the present invention. That is, the first step is a step of emitting a charged particle beam from a charged particle source. Next, the second step is a step of increasing the illuminance of the charged particle beam on the peripheral edge of the aperture of the aperture in the cleaning mode as compared with the drawing on the substrate.

<Embodiment of Device Manufacturing Method>
The method for producing an article as one aspect of the present invention is suitable for producing an article such as a microdevice such as a semiconductor device or an element having a fine structure. In the method of manufacturing an article according to the present embodiment, a pattern (latent image pattern) is transferred to a resist applied to a substrate using a drawing device or a charged particle beam drawing device, and the latent image pattern is transferred in this step. Developing (processing) the substrate. Further, the manufacturing method may include other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like). The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

Claims (11)

A charged particle beam drawing apparatus for drawing a pattern on a substrate using a charged particle beam having an illuminance distribution,
A member to be irradiated with the charged particle beam;
An adjustment unit for adjusting the illuminance distribution of the charged particle beam,
On the irradiated member irradiated with the charged particle beam, a low illuminance region where the illuminance of the charged particle beam is lower than a predetermined value occurs,
Contaminants adhere to the low illumination area on the irradiated member,
The charged particle beam drawing apparatus, wherein the adjusting unit adjusts the illuminance distribution of the charged particle beam so as to remove contaminants attached to the irradiated member. The irradiated member includes an opening for passing a part of the charged particle beam;
The low illuminance region occurs at a peripheral edge of the opening of the irradiated member,
The charged particle beam drawing apparatus according to claim 1, wherein the contaminant adheres to the peripheral edge portion of the opening of the irradiated member.   3. The illuminance of the charged particle beam at the contaminated portion is higher after the adjustment than before the adjustment by the adjustment unit. Charged particle beam drawing device.   The charged particle beam drawing apparatus according to claim 3, wherein the illuminance distribution of the charged particle beam is wider after the adjustment is performed than before the adjustment by the adjustment unit.   The charged particle beam drawing apparatus according to claim 4, wherein the adjustment unit includes an electrostatic lens and widens the illuminance distribution by adjusting a potential applied to the electrostatic lens.   The charged particle beam drawing apparatus according to claim 5, wherein the electrostatic lens is a collimator lens that converts the charged particle beam into a parallel beam.   The charged particle beam drawing apparatus according to claim 3, wherein the adjustment unit shifts the illuminance distribution of the charged particle beam on the irradiated member.   The charged particle beam drawing according to claim 7, wherein the adjustment unit includes a deflection electrode that deflects the charged particle beam, and shifts the illuminance distribution by adjusting a potential applied to the deflection electrode. apparatus.   The charged particle beam drawing according to any one of claims 1 to 8, further comprising a gas introduction part that introduces a gas selected from water vapor, oxygen, and ozone into a place where the contaminant is attached. apparatus. A method for removing contaminants in a charged particle beam drawing apparatus that draws a pattern on a substrate using a charged particle beam having an illuminance distribution,
An irradiation step of irradiating the substrate with the charged particle beam;
Adjusting the illuminance distribution of the charged particle beam, and
On the irradiated member irradiated with the charged particle beam in the irradiation step, a low illuminance region where the illuminance of the charged particle beam is lower than a predetermined value occurs,
Contaminants adhere to the low illumination area on the irradiated member,
In the adjusting step, the illuminance distribution of the charged particle beam is adjusted so as to remove the contaminant attached to the irradiated member. A step of drawing a pattern on the substrate by the charged particle beam drawing apparatus according to claim 1;
Developing the substrate;
A device manufacturing method comprising:

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