PROCESSING APPARATUS AND PROCESSING METHOD

According to one embodiment, a processing apparatus includes a chamber, a first gas introduction port that introduces a first gas into the chamber, a first gas discharge port that discharges the first gas from the chamber, and a stage that supports a processing object in the chamber. The processing apparatus has a plasma generating section with an electrode to generate a plasma in the chamber. The processing apparatus includes a shield at a first position that is between the plasma generating section and the stage. The shield is light transmissive, but blocks radicals and ions generated with plasma. In some examples, the shield may be moveable from the first position to another position that is not between the plasma generating section and the stage.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-017490, filed Feb. 4, 2020, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a processing apparatus and a processing method.

BACKGROUND

As a lithography process for the manufacturing of a semiconductor device, nanoimprint lithography has been proposed as a pattern transfer method which takes the place of photolithography. In nanoimprint lithography, a patterned template is directly pressed against a substrate coated with a liquid organic material to transfer the pattern of the template to the substrate.

DETAILED DESCRIPTION

In general, according to one embodiment, a processing apparatus includes a chamber, a first gas introduction port that introduces a first gas into the chamber, a first gas discharge port that discharges the first gas from the chamber, and a stage that supports a processing object in the chamber. The processing apparatus has a plasma generating section with an electrode. The plasma generating section is configured to generate a plasma in the chamber. The processing apparatus includes a shield at a first position that is between the plasma generating section and the stage. The shield is light transmissive.

Certain example embodiments of the present disclosure will now be described with reference to the drawings. In the drawings and in the following description, the same reference symbols are used for the same or substantially similar components or elements. The drawings are schematic; thus, the size ratio between components or elements, etc. are not necessarily to scale.

First Embodiment

A processing apparatus and a processing method according to a first embodiment will be described with reference toFIGS. 1 through 6.FIG. 1is a cross-sectional view showing the configuration of the processing apparatus according to this embodiment.FIG. 2is a top view showing a template50according to this embodiment.FIGS. 3A through 3Care cross-sectional views showing the template50according to this embodiment.

The processing apparatus of the first embodiment will be described first. The processing apparatus of this embodiment is, for example, an apparatus for smoothing a pattern already formed on a substrate (or processing object). While the following description illustrates the use of an imprinting template as a processing object, it is also possible to use a patterned semiconductor substrate (such as a semiconductor wafer or the like).

As shown inFIG. 1, the processing apparatus1includes a chamber10and a stage11. A heater12is provided for adjusting the temperature of a processing object (e.g., an imprinting template50or a template50) in the chamber10. The stage11can support the imprinting template50. The heater12heats the template50supported on the stage11to adjust the temperature of the template.

As shown inFIG. 1, the processing apparatus1includes a plasma generating section5. The plasma generating section5includes an electrode13, a power source14and a matching box (may also be referred to as an impedance matching unit, a matching network, or the like). The electrode13is provided above the stage11in the chamber10. The power source14is electrically connected by wiring to the matching box15. The matching box15is electrically connected by wiring to the electrode13. The plasma generating section5causes a high-frequency discharge in the chamber10and generates a plasma P.

A shield40is provided in the chamber10in the space between the stage11and the electrode13. The chamber10is thus divided by the shield40into a processing division6, which contains the stage11, and a light source division7, which contains the plasma generating section5. The shield40comprises, for example, glass, sapphire, calcium fluoride, magnesium fluoride, polycarbonate, or an acrylic resin. The shield40shields the processing division6from ions, radicals, etc. generated along with the plasma in the light source division7.

Gas introduction ports21(21a,21b) and gas discharge portions22(22a,22b) are provided in the chamber10. The gas introduction port21aand the gas discharge portion22aare provided in the processing division6, while the gas introduction port21band the gas discharge portion22bare provided in the light source division7. The gas discharge portions22are provided with pressure regulators23(23a,23b) for regulating the amount of exhaust gas. The gas introduction ports21may be provided with flow regulators for regulating the flow rate of an incoming gas. The gas introduction port21a,provided in the processing division6, introduces a processing gas61into the processing division6. The gas introduction port21b,provided in the light source division7, introduces a light source gas62into the light source division7.

An opening is provided in the side wall of the processing division6of the chamber10, and a gate valve16is provided such that it closes the opening.

The template50as a processing object is carried through the opening into the processing division6, and carried through the opening out of the processing division6. The processing apparatus1also includes a conveyance section or the like that places the template50on the stage11.

As shown inFIG. 2, the template50is a processed quadrangular substrate51. The substrate51is, for example, composed mainly of quartz (or other transparent material). An elevated portion53is provided in and around the center of the main surface52of the substrate51. The elevated portion53is formed of the same material as that of the substrate51. The elevated portion53is a mesa-like structure projecting from the main surface52. The elevated portion53may be referred to as a mesa structure or, more simply, a mesa in some contexts.

The elevated portion53has a patterned surface54having a three-dimensional pattern formed therein or thereon as a topographic relief structure or the like. For example, the three-dimensional pattern may comprise grooves, trenches, recesses, holes, or the like etched into the patterning surface and/or protrusions, tiers, pillars, or the like formed on the patterning surface. WhileFIG. 2illustrates the template50having a line-and-space structure as an example of a three-dimensional pattern, the three-dimensional pattern of the template50is not limited to a line-and-space structure.

FIGS. 3A through 3Cshow an example of cross-sectional structures of templates50according to this embodiment.

The template50ashown inFIG. 3Ahas the patterned surface54in which the three-dimensional pattern is formed in a resin layer55. The resin layer55is provided on a chromium layer57formed on the elevated portion53. The resin layer55is formed of, for example, a resist composed mainly of a novolac resin.

The template50bofFIG. 3B, the three-dimensional pattern is formed directly in the elevated portion53. The template50bis produced, for example, by etching using the resin layer55of the template50aas a mask.

As shown inFIG. 3C, certain fine structures56, which are three-dimensional portions finer than the main three-dimensional pattern, exist in the patterned surface54. The fine structures56may be referred to as pattern roughness, sidewall roughness, sub-pattern dimension features. The patterned surface54of the template50of this embodiment may have either the configuration of the template50aor the configuration of the template50b,but, in either case, fine structures56are present. The processing associated with removing and/or reducing such fine structures56is referred to as smoothing or leveling in this context.

A method for processing the template50using the processing apparatus1will now be described with reference toFIG. 1andFIGS. 4 through 6.FIG. 4is a diagram illustrating a processing method according to this embodiment.FIG. 5shows a plasma emission spectrum of N2gas which is a light source gas.FIGS. 6A and 6Bare diagrams schematically illustrating the processing method for the template50performed in the processing division6.

First, the gate valve16of the processing apparatus1, shown inFIG. 1, is opened, and the template50is placed in the chamber10on the stage11by the conveyance section or the like. The template50is placed with the patterned surface54facing the electrode13in the chamber10. After the placement of the template50, the gate valve16is closed.

Subsequently, a processing gas61is introduced into the processing division6of the chamber10. A light source gas62is introduced into the light source division7. Examples of the processing gas61include reactive gases such as oxygen (O2), ozone (O3), nitrous oxide (N2O), carbon monoxide (CO), carbon dioxide (CO2), fluorine (F2), nitrogen trifluoride (NF3), nitrogen tetrafluoride (NF4), hexafluoro-1,3-butadiene (C4F6), octafluorocyclobutane (C4F8), fluoroform (CHF3), difluoromethane (CH2F2), sulfur hexafluoride (SF6), chlorine (Cl2), boron trichloride (BCl3), hydrogen chloride (HCl), and hydrogen bromide (HBr). A mixed gas comprising such a reactive gas and an inert gas, such as nitrogen (N2), argon (Ar) or helium (He) may also be used. The reactive gas may be appropriately selected depending on the material and thickness of the patterned surface54of the template50, etc. The use of the reactive gas enables etching of raised portions of the fine structures56of the template50. A gas such as N2, O2, Ar or He, for example, can be used as the light source gas62. The light source gas62may be appropriately selected depending on the dissociation energy of the reactive gas used for the processing gas61, etc., as will be described below. The pressure in the processing division6and the pressure in the light source division7are regulated by the pressure regulators23. The pressure in the processing division6is regulated, for example, to about 1 Pa to about atmospheric pressure. The pressure in the light source division7is regulated, for example, to about 0.1 Pa to about 100 Pa.

Thereafter, the plasma generating section5generates a plasma P in the light source division7. The plasma P may be generated, for example, by an inductively-coupled plasma method or an electron cyclotron resonance discharge method. As shown inFIG. 4, when the plasma P is generated in the light source division7, the template50in the processing division6is irradiated with plasma light31that has passed through the shield40. In the light source division7, ions, radicals, etc. are generated along with the plasma P. However, movement of the ions and radicals to the processing division6is blocked by the shield40. Thus, the template50in the processing division6can be prevented from being etched by the ions and radicals generated in the light source division7.

A combination of the light source gas62with the reactive gas contained in the processing gas61will now be described.FIG. 5shows a plasma emission spectrum of N2gas, with the ordinate axis representing emission intensity and the abscissa axis representing emission wavelength. As shown inFIG. 5, an appreciable level of emission occurs in the wavelength range of 300 nm to 400 nm, whereas no appreciable emission occurs at a wavelength of less than 290 nm.

When N2gas is used as the light source gas62and O2gas is used as the reactive gas for the processing gas61, the O2gas dissociates into ions or radicals when it is irradiated with light having a wavelength of 242 nm or less, which corresponds to the absorption edge wavelength of O2gas. However, as described above, no appreciable emission occurs at a wavelength of less than 290 nm in the plasma emission of N2gas; therefore, dissociation of the O2gas does not occur. Accordingly, dissociation of the reactive gas, and thus etching of the template50, will not occur by merely applying the plasma light31to the processing division6. As described above, the type of the light source gas62can be appropriately selected depending on the absorption edge wavelength of the reactive gas used for the processing gas61. Thus, the emission wavelength of the light source gas62is preferably set to be longer than the absorption edge wavelength of the reactive gas contained in the processing gas61.

Instead of selecting a particular light source gas62in view of the reactive gas to be used, another method for adjusting the wavelength of the plasma light31applied to the processing division6is to impart to the shield40a function as a filter that blocks light at wavelengths shorter than the absorption edge wavelength of the processing gas61. This alternative method enables the use, as the light source gas62, of a gas which has a plasma emission spectrum containing light whose wavelength is shorter than the absorption edge wavelength of the processing gas61. The impartment of the filter function can be achieved by using, as the shield40a colored glass filter having a long-pass filter function, for example.

In this first embodiment, leveling is performed on the fine structures56shown inFIG. 3C. The processing uses light whose wavelength is longer than the absorption edge wavelength of the reactive gas used for the processing gas61. More specifically, leveling is performed using near-field light generated from the plasma light31, which has passed through the shield40and irradiates the template50, in the vicinity of the surfaces of the fine structures56.

Leveling according to this first embodiment, performed by using near-field light, will now be described. As shown inFIG. 3C, the fine structures56, which are three-dimensional portions finer than the three-dimensional pattern, exist in the patterned surface54of the template50to be subjected to leveling according to this first embodiment. Near-field light is generated when the fine structures56are irradiated with light. The near-field light is localized such that it covers the surfaces of the fine structures56. The near-field light can cause a so-called non-adiabatic photochemical reaction that directly excites molecules to a vibrational level. Therefore, even though dissociation of the reactive gas by the plasma light31does not occur, the near-field light generated at the surfaces of the fine structures56reacts with molecules of the reactive gas, and causes the gas molecules to dissociate into gas radicals.

In this first embodiment, as shown inFIG. 6A, the template50is irradiated with the plasma light31, whereby near-field light32is generated in the vicinity of the surfaces of the fine structures56. The near-field light32is unlikely to be generated in flat portions of the surface of the template50, and therefore the reactive gas is unlikely to dissociate near these flat portions. In contrast, the near-field light32is likely to be generated in the vicinity of the surfaces of the fine structures56, and therefore the reactive gas is likely to dissociate in proximity to these fine structures56. Leveling by etching of the protruding fine structures56is effected by radicals generated by the dissociation of the reactive gas. The fine structures56become smaller with the progress of leveling and, at the time when the fine structures56have been almost entirely removed, the intensity of the near-field light32is so low that its contribution to the dissociation of the reactive gas is negligible. The leveling by etching of the fine structures56is thus completed as shown inFIG. 6Bwith a substantial reduction in the size of protruding fine features56. During the leveling process, the temperature of the stage11may be adjusted by the heater12. For example, the efficiency of etching can be increased by appropriately raising the temperature of the stage11using the heater12to adjust the temperature to be in a range of room temperature to 80° C.

After the completion of leveling, the gate valve16of the processing apparatus1is opened, and the template50is detached from the stage11and then carried out of the chamber10. Thereafter, the gate valve16is closed. The template50can now be used, for example, in imprinting.

According to the processing apparatus1and the above-described processing method of this embodiment, it is possible to perform leveling of a processing object while preventing etching of the processing object that would be caused by ions or radicals generated along with a plasma. In the case of a leveling technique which utilizes near-field light and uses laser as a light source, it is necessary to provide a laser light source having a desired wavelength appropriate to the reactive gas used. However, according to the leveling technique of this embodiment, which utilizes near-field light and uses plasma light as a light source, leveling processes using different reactive gases can be performed within the same apparatus simply by changing the light source gas62.

Second Embodiment

A processing apparatus and a processing method according to a second embodiment will now be described with reference toFIGS. 7A and 7B.FIGS. 7A and 7Bare cross-sectional views showing the configuration of the processing apparatus according to the second embodiment.

The processing apparatus2according to the second embodiment differs from the first embodiment in that the shield40is connected to a moving section17so that the shield40can be moved between the position shown inFIG. 7A, where the shield40separates the processing division6from the light source division7, and the position shown inFIG. 7B, where the shield40does not separate the processing division6from the light source division7. The moving section17is depicted in this example as a hinge structure, but is not limited thereto. The second embodiment also differs in that the gas introduction port21, the gas discharge portion22and the pressure regulator23are each provided singly. The processing method according to the second embodiment further differs from the first embodiment in that when carrying the template50into or out of the chamber10, the shield40needs to be moved to the position where it does not separate the processing division6from the light source division7. Also, a mixed gas63comprising a processing gas and a light source gas is introduced into the chamber10.

A method for processing the template50using the processing apparatus2will now be described with reference toFIGS. 7A and 7B.

First, the template50is placed on the stage11in the chamber10. The shield40is in the position shown inFIG. 7B, where the shield40does not separate the processing division6from the light source division7. The position may be any position at which the shield40does not separate the processing division6from the light source division7and does not interfere with carrying-in/carrying-out of the template50.

After the gate valve16is closed, the mixed gas63is introduced from the gas introduction port21into the chamber10. When a mixed gas of N2(light source gas) and O2(reactive gas), for example, is used, the ratio of the O2gas to the N2gas may be 20% to 80%, preferably about 50%. The pressure in the chamber10may be adjusted to about 0.1 Pa to about 100 Pa.

Thereafter, the shield40is moved to the position shown inFIG. 7A, where the shield40separates the processing division6from the light source division7, to carry out leveling of the template50. The fine structures56of the template50can be leveled due to the presence of the mixed gas containing the processing gas between the template50and the shield40.

After the completion of leveling, the shield40is moved to the position shown inFIG. 7B, and the template50is carried out of the chamber10.

The processing apparatus2and the above-described processing method of this second embodiment can achieve the same effects as the first embodiment. Additionally, plasma etching processes may be performed simply by moving the shield40of the processing apparatus2to a position where it does not interfere.

Third Embodiment

A processing apparatus and a processing method according to a third embodiment will now be described with reference toFIGS. 8 and 9A to 9E.FIG. 8is a cross-sectional view showing the configuration of the processing apparatus3according to the third embodiment.FIGS. 9A through 9Eare top views and cross-sectional views illustrating a method for carrying the template50into the processing apparatus3. The processing apparatus3according to the third embodiment differs from the second embodiment in that the shield40and the moving section17are absent. Instead, a space41, which is smaller in dimension than the template50but larger than the elevated portion53, is provided in the stage11. Lifts18for lifting the template50are provided in the space41. The space41has a size sufficient to fit the three-dimensional pattern formed in the substrate placed on the stage11. The processing method according to the third embodiment differs from the second embodiment in that the template50is placed upside down on the stage11(that is, the main surface52faces towards the stage11and thus a back side of the template50faces away from the stage11).

A method for processing the template50using the processing apparatus3will now be described. First, the template50is carried upside down to the stage11in the chamber10by the conveyance arm44, as shown inFIG. 9B.

The carry-in process will be described with reference toFIGS. 9A through 9E. The lifts18each include a lift pin42and an air cylinder43. The air cylinder43vertically moves the lift pin42. The lift pin42moves the template50up and down. Before the template50is carried in, the lift pins42are in a lowered state as shown inFIG. 9A. The template50is carried in by the conveyance arm44while the lift pins42are in a lowered state, as shown inFIG. 9B. Thereafter, as shown inFIG. 9C, the lift pins42move upward and lift the template50from the conveyance arm44. Subsequently, as shown inFIG. 9D, the conveyance arm44is withdrawn from under the template50. The conveyance arm44moves out of the chamber10, and then the gate valve16is closed. After the gate valve16is closed, the mixed gas63is introduced into the chamber10. When the mixed gas63is introduced into the chamber10, the template50is still in a raised state, as shown inFIG. 9D. Accordingly, the mixed gas63is also introduced into the space41(located below the template50) at this time. After the introduction of the mixed gas63, the lift pins42are lowered and the template50is placed on the stage11, as shown inFIG. 9E. As a result, as shown inFIGS. 8 and 9E, the space41is isolated by the combination of the template50and the stage11. Thus, the for the reversed template50, the substrate51itself performs substantially the same function as the shield40in the previous embodiments.

After lowering the template50, leveling of the template50is performed. After the completion of leveling, the template50is carried out of the chamber10. The carrying-out of the template50is performed by reversing the carry-in process (excepting for the introduction of the mixed gas63, which is not carried out in the carrying-out process).

According to the processing apparatus3and the above-described processing method of this third embodiment, the substrate51itself of a reverse facing template50performs the same function as the shield40. Therefore, the same effects as the first embodiment can be achieved. Furthermore, by just reversing the facing direction of the template50placed on the stage11, the processing apparatus3can also be used to perform plasma etching, as in the second embodiment.

Fourth Embodiment

A processing method according to a fourth embodiment will now be described with reference toFIGS. 10A and 10B.FIGS. 10A and 10Bare diagrams illustrating a method for processing the template50in the processing division6according to this embodiment. The processing method according to the fourth embodiment is performed using the processing apparatus1as in the first embodiment. This fourth embodiment differs from the first embodiment in that instead of the reactive gas, another gas (deposition gas) is used for the processing gas61. The fourth embodiment is otherwise the same as the first embodiment. The use of another gas for the processing gas61makes it possible to deposit a material in recessed portions of the fine structures56of the template50. Examples of gases which can be used in this context include methane (CH4), propylene (C3H6), carbon tetrafluoride (CF4), fluoroform (CHF3), hexafluoroethane (C2F6), hexafluoro-1,3-butadiene (C4F6), octafluorocyclobutane (C4F8), silane (SiH4), disilane (Si2H6), dichlorosilane (SiH2Cl2), trichlorosilane (SiHCl3), and silicon tetrachloride (SiCl4). By controlling a bias voltage, applied to the electrode upon the generation of a plasma, and the density of the plasma, both etching and deposition can be performed. Thus, depending on the applied bias voltage, CF4, CHF3, C4F6and C4F8may be used both as a reactive gas and as a deposition gas.

In the processing method of this fourth embodiment, the template50is irradiated with plasma light31, as shown inFIGS. 10A and 10B, whereby near-field light32is generated in the vicinity of the surfaces of the fine structures56of the template50. The energy of the plasma light31is less than the dissociation energy of the deposition gas. Furthermore, the near-field light32is unlikely to be generated in flat (non-recessed) portions of the surface of the template50, and therefore the deposition gas is unlikely to react (be deposited) on these flat portions. In contrast, the near-field light32is likely to be generated in the vicinity of the surfaces of the fine structures56, and therefore the deposition gas is likely to react and be deposited. Leveling of the fine structures56is provided through deposition of the material produced by the reaction of the deposition gas. The fine structures56thus become smaller with the progress of leveling. At the time when the fine structures56have been almost entirely removed, the intensity of the near-field light32will be so low that its contribution to the reaction of the deposition gas will be negligible. The leveling of the fine structures56(more particularly, those fine structures56which comprise recesses) through deposition is thus completed.

According to the processing apparatus1and above-described processing method of this fourth embodiment, it is possible to perform leveling of a processing object while preventing etching of the processing object that would otherwise be caused by ions or radicals generated along with a plasma. In the case of a leveling technique which utilizes near-field light and uses laser as a light source, it is necessary to provide a laser light source having a desired wavelength appropriate to the deposition gas used. However, according to the leveling technique of this fourth embodiment, which utilizes near-field light and uses plasma light as a light source, leveling processes using different deposition gases can be performed within the same apparatus simply by changing the light source gas62.

Fifth Embodiment

A processing method according to a fifth embodiment will now be described. The processing method according to the fifth embodiment is performed using the processing apparatus2as in the second embodiment. This fifth embodiment differs from the second embodiment in that instead of the reactive gas, a deposition gas is used for the processing gas61in the processing. This embodiment is otherwise the same as the second embodiment.

The processing apparatus2and processing method of this fifth embodiment can achieve the same effect as the fourth embodiment. Plasma etching can also be performed by moving the shield40of the processing apparatus2to a position where it does not interfere between the electrode13and the template50.

Sixth Embodiment

A processing method according to a sixth embodiment will now be described. The processing method according to the sixth embodiment is performed using the processing apparatus3as in the third embodiment. This sixth embodiment differs from the third embodiment in that instead of the reactive gas, a deposition gas is used for the processing gas61in the processing. This sixth embodiment is otherwise the same as the third embodiment.

The processing method of this sixth embodiment can achieve the same effects as the fourth embodiment. Furthermore, by reversing the direction of the template50placed on the stage11, the processing apparatus3can also perform plasma etching, as in the second embodiment.