WO2016170729A1

WO2016170729A1 - Imprint apparatus, method of imprinting, and method of manufacturing article

Info

Publication number: WO2016170729A1
Application number: PCT/JP2016/001701
Authority: WO
Inventors: Toshiaki Yamazaki; Hitoshi Nakano
Original assignee: Canon Kabushiki Kaisha
Priority date: 2015-04-22
Filing date: 2016-03-24
Publication date: 2016-10-27

Abstract

An imprint apparatus (100) for forming a pattern of an imprint material on a substrate (4) by using a mold (9) includes a capturing unit having a capture area (31b) for capturing a particle with electrostatic force such that the capture area surrounds a placement space for the substrate or a holder for the substrate.

Description

IMPRINT APPARATUS, METHOD OF IMPRINTING, AND METHOD OF MANUFACTURING ARTICLE

The present invention relates to an imprint apparatus, a method of imprinting, and a method of manufacturing an article.

A known imprint apparatus forms a fine pattern on a substrate (wafer) for manufacture of, for example, a semiconductor device. The imprint apparatus brings an imprint material on the substrate into contact with a mold having a pattern-formed portion (hereinafter, referred to as a pattern portion), and applies energy for hardening to the imprint material, thus forming a pattern made of the hardened material.

When the mold is separated from the imprint material, the mold becomes charged (hereinafter, this will be referred to as "separation charging"). The pattern portion of the mold tends to capture charged particles in the vicinity of the mold. If the pattern portion of the mold with the captured particles is brought into contact with an imprint material, a pattern formed on a substrate may have a defect.

PTL 1 describes a technique for charging part of a mold or a mold holding mechanism such that the part functions as a particle capture area to prevent a pattern portion of the mold from capturing particles in an atmosphere. PTL 1 describes that the particle capture area is disposed upstream of a position (imprinting position), where a substrate faces the mold, in a conveying direction in which the substrate is conveyed to the imprinting position.

However, particles may suspend in all directions relative to the pattern portion. In the particle capture area disclosed in PTL 1, the pattern portion may capture particles approaching the pattern portion in directions other than the conveying direction (i.e., from the upstream side to a downstream side in the conveying direction).

Japanese Patent Laid-Open No. 2014-175340

An aspect of the present invention provides an imprint apparatus and an imprinting method that reduce a likelihood that particles may be sandwiched between a mold and a substrate when the mold is brought into contact with an imprint material on the substrate.

According to an aspect of the present invention, an imprint apparatus for forming a pattern of an imprint material on a substrate by using a mold includes a capturing unit having a capture area for capturing a particle with electrostatic force such that the capture area surrounds a placement space for the substrate.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Fig. 1 is a diagram illustrating an imprint apparatus according to a first embodiment. Fig. 2A is a plan view of a charging plate surrounding a mold. Fig. 2B is a plan view of the charging plate surrounding the mold. Fig. 2C is a plan view of the charging plate surrounding the mold. Fig. 3A is a plan view of a charging plate surrounding a wafer. Fig. 3B is a plan view of the charging plate surrounding the wafer. Fig. 3C is a plan view of the charging plate surrounding the wafer. Fig. 4A is a diagram explaining a first advantage of the first embodiment. Fig. 4B is a diagram explaining the first advantage of the first embodiment. Fig. 5A is a diagram explaining a second advantage of the first embodiment. Fig. 5B is a diagram explaining the second advantage of the first embodiment. Fig. 6 is a diagram illustrating an imprint apparatus according to a second embodiment. Fig. 7A is a diagram illustrating an imprint apparatus according to a fourth embodiment. Fig. 7B is a diagram illustrating the imprint apparatus according to the fourth embodiment. Fig. 8 is a flowchart of voltage control in the fourth embodiment. Fig. 9 is a timing diagram of the voltage control in the fourth embodiment. Fig. 10A is a schematic diagram of an imprint apparatus according to a fifth embodiment. Fig. 10B is a schematic diagram of the imprint apparatus according to the fifth embodiment. Fig. 11 is a diagram illustrating an imprint apparatus according to a seventh embodiment. Fig. 12A is a plan view of a charging plate surrounding a wafer in an eighth embodiment. Fig. 12B is a cross-sectional view illustrating the charging plate surrounding the wafer in the eighth embodiment. Fig. 13 is a plan view of a charging plate surrounding the wafer in a modification of the eighth embodiment. Fig. 14 is a plan view of a charging plate surrounding a mold in the eighth embodiment.

First Embodiment

Fig. 1 illustrates an imprint apparatus 100 according to a first embodiment. The imprint apparatus 100 brings a mold 9 into contact with an imprint material 4a on a wafer (substrate) 4, hardens the imprint material 4a in contact with the mold 9, and then separates the mold 9 from the hardened imprint material 4a, thus forming a pattern made of the imprint material 4a on the wafer 4. The term "Z axis or direction" as used herein refers to the vertical axis or direction, and the terms "X axis or direction" and "Y axis or direction" refer to two axes or directions orthogonal to each other in a plane perpendicular to the Z axis. Examples of the imprint material 4a used include a photo-curing composition.

The imprint apparatus 100 includes a base surface plate 2, a stage surface plate 3 on the base surface plate 2, a chuck 5 that holds the wafer 4, and a stage 6 that moves together with the chuck 5 on the stage surface plate 3. The imprint apparatus 100 further includes a strut 7 disposed on the base surface plate 2, a mold holding mechanism (hereinafter, referred to as a "holding mechanism") 10, and a bridge surface plate 8. The bridge surface plate 8 is supported by the strut 7, and supports the holding mechanism 10.

The holding mechanism 10 holds the mold 9 with a mold chuck (not illustrated). The holding mechanism 10 includes a mold driving mechanism (not illustrated) capable of positioning the mold 9 in at least the Z direction. The mold driving mechanism may be capable of positioning the mold 9 in other directions (e.g., six axial directions including the X direction, the Y direction, and rotation directions about the X axis, the Y axis, and the Z axis).

The chuck 5 holds the wafer 4 by reducing the pressure in a space between the wafer 4 and the chuck 5. The stage 6 includes a top plate (not illustrated) on which the chuck 5 is mounted and a stage driving mechanism (not illustrated) that drives the top plate. The stage driving mechanism includes linear motors and air cylinders, and positions the wafer 4 in at least the X and Y directions using the linear motors and the air cylinders. The stage driving mechanism may position the wafer 4 in two or more axial directions (e.g., six axial directions). The position of the stage 6 is measured using, for example, a laser interferometer.

The imprint apparatus 100 further includes an irradiation unit 11, which is disposed on the bridge surface plate 8. The irradiation unit 11 emits ultraviolet light 22 for curing the imprint material 4a. The emitted ultraviolet light 22 is reflected by a mirror 21 and is then applied to the wafer 4.

The mold 9 has a pattern portion 9a that serves as a pattern-formed surface facing the wafer 4 (in a negative Z direction). The pattern portion 9a has a relief pattern having a line width of, for example, several tens of nanometers. A surface of the mold 9 opposite from the pattern portion 9a is held by the above-described mold chuck. The mold 9 can be made of a material that permits the ultraviolet light 22 to pass therethrough, for example, quartz.

The imprint apparatus 100 further includes a mold-side capturing unit (second capturing unit). Part of the mold-side capturing unit is disposed on lower part of the holding mechanism 10. In the present embodiment, the mold-side capturing unit includes an electrostatic chuck 12, a charging plate 13 held by the electrostatic chuck 12, and a voltage source 14 that is connected to the electrostatic chuck 12 and the charging plate 13 to supply a voltage to these components. The electrostatic chuck 12 is disposed on the lower part of the holding mechanism 10. The charging plate 13 is disposed on the opposite side (facing the wafer) of the electrostatic chuck 12 from the holding mechanism 10.

The charging plate 13 is a rectangular conductive plate having a rectangular opening 13a (see Fig. 2A). The charging plate 13 has the same shape as that of the electrostatic chuck 12. On the charging plate 13, a capture area (second capture area) 13b for capturing (collecting) charged particles with electrostatic force is formed so as to surround a placement space for the mold 9. The capture area 13b extends along the mold 9.

In the present embodiment, the term "placement space for the mold 9" refers to a space occupied by the mold 9 when the mold 9 is placed in the space.

In the present embodiment, the term "surrounding the placement space for the mold 9" means that at least the capture area 13b surrounds the perimeter of the placement space for the mold 9 when the placement space and the charging plate 13 are viewed in a direction perpendicular to the pattern portion 9a of the mold 9. Furthermore, this term means that, when the mold 9 is placed, the side surfaces (extending vertically) of the mold 9 face part (the electrostatic chuck 12 and the charging plate 13 in the present embodiment) of the mold-side capturing unit.

Fig. 2A is a plan view of the mold 9 and the charging plate 13 in the present embodiment when viewed from directly below. The capture area 13b may be a rectangular area surrounding or extending along four sides of an outer shape of the placement space (second space) for the mold 9. In Fig. 2A, the placement space for the mold 9 is the same space as that occupied by the mold 9. The outer shape of the placement space is the shape of the placement space viewed in the vertical direction (Z direction). The capture area 13b can be provided by the continuous and rectangular charging plate 13 as in the first embodiment.

The length of each side of the outer shape of the charging plate 13 is, for example, less than or equal to 3.0 times the length of the corresponding side of the mold 9. If the length of the side of the outer shape of the charging plate 13 is too short, it would result in a reduction in area of capture for particles 20 (see Figs. 4A and 4B). If the length thereof is too long, it would result in an increase in size of the imprint apparatus 100.

To apply external force to a side surface of the mold 9 during imprinting in order to correct the shape of the pattern portion 9a, for example, an actuator for shape correction is disposed between the mold 9 and the charging plate 13 (i.e., in a region that is inside the rectangular opening 13a of the charging plate 13 and is outside the mold 9). In this case, the length of each side of the outer shape of the charging plate 13 is preferably greater than or equal to 1.5 times the length of the corresponding side of the mold 9.

Although Fig. 2A illustrates the continuous charging plate 13, the charging plate 13 may have any shape that can provide the capture area 13b surrounding the placement space for the mold 9. The charging plate 13 may be shaped such that four corners are removed and the charging plate 13 is composed of four segments as illustrated in Fig. 2B. Alternatively, as indicated by dashed lines in Fig. 2C, the electrostatic chuck 12 may include segments arranged such that each of the segments is located in part of a portion of the charging plate 13 extending along each side of the charging plate 13. In this case, the capture area 13b is also provided in part of the portion extending along each side of the charging plate 13. The capture areas 13b can be arranged along the four sides of the placement space. The capture area 13b may be ring-shaped so as to surround the mold 9.

In the mold-side capturing unit, the voltage source (second control unit) 14 controls the voltage to charge the capture area 13b. This enables the electrostatic chuck 12 to attract and hold the charging plate 13, and allows the capture area 13b to generate an electric field. The generated electric field captures charged particles. The voltage source 14 controls the supply voltage such that the capture area 13b is charged with the same polarity as that of the mold 9.

A measuring instrument (not illustrated) for determining the polarity of charge in the mold 9 may be disposed and the polarity of the voltage supplied by the voltage source 14 may be determined based on the determination result of the measuring instrument. Alternatively, the voltage source 14 may charge the capture area 13b with the same polarity as a polarity with which the mold 9 tends to be charged. The polarity with which the mold 9 tends to be charged due to separation charging is determined by the relationship between the material of the mold 9 and that of the imprint material 4a.

For example, when the imprint material 4a made of a urethane-based, acrylic-based, or epoxy-based material is brought into contact with the mold 9 made of quartz, the mold 9 tends to be changed positively and the imprint material 4a tends to be charged negatively. If the above-described measuring instrument is not disposed, therefore, the voltage source 14 can charge the capture area 13b positively.

The imprint apparatus 100 further includes a wafer-side capturing unit (capturing unit or first capturing unit). In the present embodiment, the wafer-side capturing unit includes an electrostatic chuck 30, a charging plate 31 disposed on the electrostatic chuck 30, and a voltage source (control unit or first control unit) 32 that is connected to the electrostatic chuck 30 and the charging plate 31 to supply a voltage to these components. The electrostatic chuck 30 is disposed on the stage 6 so as to surround the perimeter of a placement space (first space) for the wafer 4. In Figs. 5A and 5B, the placement space for the wafer 4 is the same as a space where the wafer 4 is placed.

The charging plate 31 is a conductive plate having the same shape as that of the electrostatic chuck 30. On the charging plate 31, a capture area (first capture area) 31b for capturing (collecting) charged particles with electrostatic force is formed so as to surround the placement space for the wafer 4. The capture area 31b extends along the wafer 4.

In the present embodiment, the term "placement space for the wafer 4" refers to a space occupied by the wafer 4 when the wafer 4 is placed in the space.

In the present embodiment, the term "surrounding the placement space for the wafer 4" means that at least the capture area 31b surrounds the perimeter of the placement space for the wafer 4 when the placement space and the charging plate 31 are viewed in a direction perpendicular to a surface, on which a pattern is to be formed, of the wafer 4 placed. Furthermore, this term means that, when the wafer 4 is placed, the side surfaces (extending vertically) of the wafer 4 face part (the electrostatic chuck 30 and the charging plate 31 in the present embodiment) of the wafer-side capturing unit.

Fig. 3A is a plan view of the wafer 4 and the charging plate 31 in the present embodiment when viewed from directly above. The charging plate 31 can have an outside diameter less than or equal to 2.0 times the outside diameter of the wafer 4.

In the wafer-side capturing unit, the voltage source (control unit or first control unit) 32 controls the voltage to charge the capture area 31b. This enables the electrostatic chuck 30 to attract and hold the charging plate 31, and allows the capture area 31b to generate an electric field. The generated electric field captures charged particles. The voltage source 32 controls the supply voltage such that the capture area 31b is charged with the same polarity as that of the mold 9.

A measuring instrument (not illustrated) for determining the polarity of charge in the mold 9 may be disposed and the polarity of the voltage supplied by the voltage source 32 may be determined based on the determination result of the measuring instrument. Alternatively, the voltage source 32 may charge the capture area 31b with the same polarity as a polarity with which the mold 9 tends to be charged. If the above-described measuring instrument is not disposed, therefore, the voltage source 32 may charge the capture area 31b positively.

For "surrounding the placement space for the wafer 4", as illustrated in Fig. 3B, the electrostatic chuck 30 may include segments and the charging plate 31 may include segments such that the segments discontinuously surround the wafer 4. The term "discontinuously surrounding" means a state in which the segments surround eighty percent or more of the perimeter of the placement space for the wafer 4. Furthermore, as illustrated in Fig. 3C, the segments of the electrostatic chuck 30 may be arranged such that the capture areas 31b discontinuously surround the placement space for the wafer 4.

Referring again to Fig. 1, the imprint apparatus 100 further includes an observation system 15 that is disposed directly above the mold 9. The observation system 15 detects an alignment mark in the pattern portion 9a and an alignment mark (not illustrated) on the wafer 4. The imprint apparatus 100 further includes a supply unit 16 for supplying the imprint material 4a in an uncured state to a predetermined position when the wafer 4 is positioned under the supply unit 16.

The imprint apparatus 100 further includes a controller 17. The controller 17 is connected to the stage 6, the holding mechanism 10, the irradiation unit 11, the

voltage sources

14 and 32, the observation system 15, and the supply unit 16. The control unit 17 controls these components in a centralized manner to execute an imprinting process. The term "imprinting process" as used herein refers to a process of repeating a series of operations, i.e., supplying the imprint material 4a to a pattern formation area (not illustrated) on the wafer 4, bringing the mold 9 into contact with the imprint material 4a, hardening the imprint material 4a, and separating the mold 9 from the imprint material 4a.

The imprint apparatus 100 according to the present embodiment can reduce the phenomenon in which the pattern portion 9a captures particles in the imprint apparatus 100. The reduction of the phenomenon will now be described.

Figs. 4A and 4B are diagrams explaining a first advantage of the first embodiment. Fig. 4A illustrates a state in which when supply of the imprint material 4a from the supply unit 16 to the wafer 4 is finished while the stage 6 is stopped, the particle 20 charged negatively in the apparatus falls on one end of the wafer 4. Fig. 4B illustrates a state in which the stage 6 is being driven and moved from a position where the imprint material 4a faces the supply unit 16 to another position (under the pattern portion 9a) where the imprint material 4a faces the mold 9. The capture area 13b can attract and capture the particle 20 passing below the charging plate 13 with electrostatic force (static electricity).

Figs. 5A and 5B are diagrams explaining a second advantage of the first embodiment. Fig. 5A illustrates a state in which supply of the imprint material 4a from the supply unit 16 to the wafer 4 is finished while the stage 6 is stopped. Fig. 5B illustrates a state in which a flow of air caused by driving the stage 6 allows the particle 20 charged negatively to move toward and under the mold 9. As illustrated in Fig. 5B, the capture area 13b can attract and capture the particle 20 with electrostatic force.

Although the capture of the particle 20 by the capture area 13b has been described with reference to Figs. 4A to 5B, the capture area 31b adjacent to the wafer 4 can also capture the particle 20.

As described above, the

capture areas

13b and 31b are charged with the same polarity as the polarity with which the mold 9 is charged. As illustrated in Figs. 4A and 4B, the particles 20 deposited on the stage 6 can be captured by the charging plate 13 surrounding the pattern portion 9a. In addition, the particles 20 moving along with the air flow, caused by driving the stage 6, toward and under the mold 9 can also be captured by the charging plate 13 surrounding the pattern portion 9a.

This reduces a likelihood that the particles 20 charged negatively may be captured by the pattern portion 9a upon separation charging. Additionally, this reduces a likelihood that the particles 20 may be sandwiched between the mold 9 and the wafer 4 when the mold 9 is brought into contact with the imprint material 4a. Consequently, a pattern defect and breakage of the pattern portion 9a of the mold 9 caused by the particles 20 can be prevented.

Furthermore, at least one of the

voltage sources

14 and 32 can supply the voltage such that the absolute value of the potential of the corresponding one of the

capture areas

13b and 31b is greater than that of the mold 9. This enables the particles 20 to be easily captured by the corresponding one of the charging

plates

13 and 31 rather than the mold 9. In particular, if the voltage source 32 allows the absolute value of the potential of the capture area 31b to be greater than that of the mold 9, the particle 20 captured by the charging plate 31 can be prevented from moving to the mold 9 when approaching the mold 9.

Second Embodiment

Fig. 6 illustrates an imprint apparatus 120 according to a second embodiment of the present invention. The imprint apparatus 120 includes the components other than the charging plate 13 and the electrostatic chuck 12 in the imprint apparatus 100.

The voltage source 32 supplies a voltage of, for example, approximately 0.5 to 5 kV. The distance between the mold 9 and the wafer 4 is approximately several millimeters. The voltage source 32 supplies the voltage such that the charging plate 31 is charged with the same polarity as that of the mold 9. Thus, the particles 20 that are likely to adhere to the mold 9 can be captured by only the electric field generated from the charging plate 31.

The potential of the mold 9 can be measured using a measuring instrument (not illustrated). The voltage source 32 can supply the voltage based on the measurement result such that the potential of the charging plate 31 is higher than that of the mold 9. Consequently, not only the particles 20 that are likely to adhere to the mold 9 but also the particles 20 that tend to separate from the mold 9 and that are some of the particles 20 deposited on the mold 9 can be attracted to and captured by the charging plate 31.

The second embodiment offers the same advantages as those of the first embodiment. Specifically, the likelihood that the particles 20 may be sandwiched between the mold 9 and the wafer 4 when the mold 9 is brought into contact with the imprint material 4a can be reduced, thus preventing a pattern defect and breakage of the pattern portion 9a of the mold 9 caused by the particles 20. Additionally, in contrast to the first embodiment, the imprint apparatus 120 according to the second embodiment has a simplified configuration.

Third Embodiment

An imprint apparatus according to a third embodiment has the same configuration as that of the imprint apparatus 100 according to the first embodiment. The third embodiment differs from the first embodiment in that each of the voltage source 14 and the voltage source 32 controls a supply voltage such that the

capture areas

13b and 31b are charged with opposite polarities. In the third embodiment, the capture area 31b is charged positively and the capture area 13b is charged negatively.

Particles 20 charged negatively are captured by the capture area 13b instead of by the pattern portion 9a positively charged due to separation charging. On the other hand, particles 20 charged positively are attracted to the capture area 31b instead of to the imprint material 4a negatively charged due to separation charging and its surrounding shot areas.

Since the

voltage sources

14 and 32 control the supply voltages such that the charging

plates

13 and 31 are charged with opposite polarities, the particles 20 charged positively and the particles 20 charged negatively can be captured. This reduces the likelihood that the particles 20 may be sandwiched between the mold 9 and the wafer 4 when the mold 9 is brought into contact with the imprint material 4a, thus preventing a pattern defect and breakage of the pattern portion 9a of the mold 9 caused by the particles 20.

If each of the

capture areas

13b and 31b is charged with the polarity opposite to that in the third embodiment, the same advantages can be obtained.

Fourth Embodiment

Figs. 7A and 7B illustrate an imprint apparatus 200 according to a fourth embodiment. The imprint apparatus 200 has the same configuration as that of the imprint apparatus 100 according to the first embodiment. Each of the

voltage sources

14 and 32 supplies a voltage with the same polarity as that in the third embodiment, namely, such that the capture area 13b is charged positively and the capture area 31b is charged negatively.

In imprinting for some of pattern formation areas (shot areas) on the wafer 4, the charging plate 13 approaches the charging plate 31 while part of the charging plate 13 faces part of the charging plate 31. If part of the charging plate 13 approaches part of the charging plate 31 while the charging

plates

13 and 31 are charged with opposite polarities and the potential difference between these plates is large, electric discharge may occur. The charging

plates

13 and 31 may be burned by electric discharge, and may have to be replaced. Furthermore, electric discharge noise may cause errors in, for example, the

voltage sources

14 and 32.

According to the fourth embodiment, the voltage supplied from each of the

voltage sources

14 and 32 is changed based on details of a pattern forming operation during this operation, thereby minimizing the possibility of electric discharge. The term "during the pattern forming operation" means a time period between the time when the imprint material 4a is supplied to a pattern formation area on the wafer 4 and the time when the mold 9 is separated from the imprint material 4a subjected to molding.

Fig. 8 is a flowchart of a process of forming a pattern in each area on one wafer 4. The controller 17 runs a program represented by the flowchart. At the start of the process illustrated by the flowchart, the electrostatic chuck 12 holds the charging plate 13 and the electrostatic chuck 30 holds the charging plate 31.

The voltage source 14 supplies a set voltage (of +2 kV in the present embodiment) to charge the capture area 13b such that the capture area 13b has a predetermined potential. Similarly, the voltage source 32 supplies a set voltage (of -2 kV in the present embodiment) to charge the capture area 31b such that the capture area 31b has a predetermined potential (S101).

The controller 17 then allows the supply unit 16 to supply the imprint material 4a to the wafer 4 (S102).

The controller 17 drives the stage 6 to move the wafer 4 to a position where the wafer 4 faces the mold 9 (S103). The controller 17 determines whether the wafer 4 is positioned at an imprinting position (S104).

When determining that the wafer 4 is not positioned (NO in S104), the controller 17 drives the stage 6 until the wafer 4 is positioned at the imprinting position. When determining that the wafer 4 is positioned (YES in S104), the controller 17 starts to drive the mold 9 in the Z direction in order to move the mold 9 downward from its standby position (S105). Simultaneously with starting to move the mold 9 downward, the controller 17 controls the

voltage sources

14 and 32 such that the absolute value of the voltage supplied from each of the voltage sources is reduced from 2 kV to 1 kV (S106). Reducing the voltage reduces electrostatic force generated from each of the

capture areas

13b and 31b.

Consequently, electric discharge does not tend to occur when the charging plate 13 approaches the charging plate 31. The controller 17 performs an imprinting operation (S107). The imprinting operation involves aligning the mold 9 with the wafer 4 while the mold 9 is in contact with the imprint material 4a, irradiating the imprint material 4a with the ultraviolet light 22 to harden the imprint material 4a, and separating the mold 9 from the imprint material 4a.

At the completion of the imprinting operation, the controller 17 starts to drive the mold 9 in the Z direction in order to move the mold 9 upward to the standby position, thus separating the mold 9 from the imprint material 4a (S108). The controller 17 determines whether the mold 9 is returned to the standby position (S109). When determining that the mold 9 is not returned to the standby position (NO in S109), the controller 17 moves the mold 9 upward until the mold 9 is returned to the standby position. When determining that the mold 9 is returned to the standby position (YES in S109), the controller 17 controls the

voltage sources

14 and 32 to increase the absolute value of the potential of each of the charging

plates

13 and 31 from 1 kV to 2 kV (S110).

The controller 17 determines whether the patterns are formed in all of the shot areas (S111). When determining that formation of the patterns is not completed (NO in S111), the controller 17 repeats steps S102 to S111. When determining that the formation of the patterns is completed (YES in S111), the controller 17 terminates the program.

Fig. 9 is a graph illustrating the relationship between a change in position of the mold 9 over time and a change in voltage applied to the charging plate 13 over time. The controller 17 changes the voltage of each of the

voltage sources

14 and 32 at the time when the controller 17 starts to move the mold 9 downward and at the time when the controller 17 completes moving the mold 9 upward.

As described above, the controller 17 controls the

voltage sources

14 and 32 such that the voltage applied to each of the charging

plates

13 and 31 is reduced when the charging

plates

13 and 31 charged with opposite polarities approach each other. Specifically, when the distance between the charging

plates

13 and 31 in the Z direction is a second distance that is less than a first distance, each of the

voltage sources

14 and 32 supplies a voltage lower than a voltage for the first distance to the corresponding charging plate. This prevents electrostatic force acting between the charging

plates

13 and 31 from excessively increasing and causing electric discharge.

In the fourth embodiment, the voltages supplied from the

voltage sources

14 and 32 are changed by the same amount at the same time. The voltages may be controlled such that the potential difference between the

capture areas

13b and 31b is reduced. At least one of the

voltage sources

14 and 32 may change the supply voltage.

In addition, the timing of voltage control for the charging plate 13 may differ from that for the charging plate 31. Furthermore, the

voltage sources

14 and 32 may be controlled such that the voltage supplied from each voltage source is reduced before the start of downward movement of the mold 9 or such that the voltage supplied from each voltage source is returned to its original value before the mold 9 is returned to the standby position. In this case, a threshold for the distance between the charging

plates

13 and 31 in the Z direction can be set. When electric discharge is likely to occur, the voltage supplied from each voltage source can be changed.

The voltage may be gradually increased or reduced. To generate force for attracting the particles 20, a high voltage can be applied to each of the charging

plates

13 and 31. To prevent electric discharge, a low voltage can be applied during downward movement of the mold 9. In this case, it is necessary to prevent the voltage from being too low (e.g., 0 V) because a too low voltage may release the captured particles 20.

Fifth Embodiment

An increase in amount of the particles 20 captured in the

capture areas

13b and 31b leads to a reduction in capacity for capturing new particles 20. It is therefore necessary to periodically replace at least one charging plate. Figs. 10A and 10B illustrate an exemplary configuration of an imprint apparatus 300 according to a fifth embodiment.

The imprint apparatus 300 includes a conveying mechanism (replacing mechanism) 40 in addition to the same components as those of the imprint apparatus 100. As illustrated in Fig. 10B, the conveying mechanism 40 has an extendable structure. The conveying mechanism 40 automatically conveys the charging plate 13 out of the imprint apparatus 300 periodically, or at regular intervals (at predetermined time). For the timing of replacement, for example, the replacement is performed each time the imprint apparatus 300 is operated for a predetermined period or each time a predetermined number of wafers 4 are subjected to pattern formation.

While the conveying mechanism 40 is partially located under the charging plate 13, the voltage source 14 is controlled to reduce the voltage supplied from the voltage source 14. Thus, the charging plate 13 can be easily detached. The reason is that a reduction in voltage supplied from the voltage source 14 allows force caused by the weight of the charging plate 13 to be greater than force, caused by the electrostatic chuck 12, for attracting the charging plate 13.

The conveying mechanism 40 includes a portion 41 for supporting the charging plate 13. The area of the portion 41 can be greater than that of the capture area 13b of the charging plate 13. Furthermore, the portion 41 of the conveying mechanism 40 has a concave surface. The concave surface can be charged positively. This prevents the particles 20, which tend to fly due to a reduction in capturing force in the capture area 13b during replacement, from flying in the imprint apparatus 300.

Then, the conveying mechanism 40 conveys a charging plate (not illustrated) different from the detached charging plate 13 into the imprint apparatus 300, and permits the charging plate to be attracted to the electrostatic chuck 12.

As described above, like the imprint apparatus 100, the imprint apparatus 300 can capture the particles 20 and prevent a pattern defect and breakage of the mold 9. The imprint apparatus 300 can prevent a reduction in force for capturing the particles 20 by replacing the charging plate 13 at proper time.

Since the imprint apparatus 300 includes the conveying mechanism 40, an open space in the imprint apparatus 300 can be minimized as compared with a case where a person enters the imprint apparatus 300 and replaces the charging plate 13. This reduces a likelihood that new particles may enter the imprint apparatus 300 during replacement of the charging plate 13. Consequently, this reduces a likelihood that the particles 20 may be captured by the pattern portion 9a.

Sixth Embodiment

The imprint material 4a in the uncured state may be discharged in the form of a fine mist or droplets from the supply unit 16 and the droplets may be captured by the wafer 4. If the droplets of the uncured imprint material 4a are captured by any of the pattern formation areas to which the imprint material 4a is not supplied, a pattern defect would be caused upon pattern formation in this area. The imprint apparatus can include a charging mechanism (not illustrated), such as an ionizer, for charging the droplets of the imprint material 4a such that the charging mechanism is placed between the supply unit 16 and the wafer 4.

For example, when negative charge is applied to the imprint material 4a in the vicinity of the supply unit 16, the charging plate 13 can capture the droplets of the imprint material 4a. This prevents the droplets from being captured by the wafer 4. If the capturing force of the charging plate 13 is too strong, the imprint material 4a to be supplied to the wafer 4 would be attracted to the charging plate 13. The voltage source 14 controls a voltage applied to the charging plate 13 accordingly.

Seventh Embodiment

Fig. 11 illustrates an imprint apparatus 400 according to a seventh embodiment. The imprint apparatus 400 includes a ring-shaped gas outlet 45 for forming an air curtain 46 in addition to the same components as those of the imprint apparatus 100. Referring to Fig. 11, the gas outlet 45 is suspended so as to surround the holding mechanism 10. If the flow rate of gas is adjusted so that the air curtain 46 reaches the base surface plate 2, the particles 20 can be prevented from entering a space 47 defined by the air curtain 46.

Like the imprint apparatus 100, the imprint apparatus 400 can capture the particles 20 in the

capture areas

13b and 31b and prevent a pattern defect and breakage of the mold 9. Furthermore, the imprint apparatus 400 can reduce the amount of particles 20 suspended around the mold 9 by using the air curtain 46, thus reducing the amount of particles 20 collected by the charging plate 13 per unit time. Thus, the imprint apparatus 400 can reduce the frequency of replacement of the charging plate 13 as well as offer the same advantages as those of the first embodiment.

Eighth Embodiment

In the mold-side capturing unit and the wafer-side capturing unit, the

electrostatic chucks

12 and 30 may be eliminated as long as these units each provide a charged capture area in any other manner. The

voltage sources

14 and 32 may be eliminated as long as these units each provide a charged area at all times.

For another wafer-side capturing unit, a charging plate 50 that provides a capture area for capturing the particles 20 will now be described with reference to Figs. 12A and 12B. Fig. 12A is a plan view of the charging plate 50 when viewed from directly above. Fig. 12B is a cross-sectional view illustrating the charging plate 50 of Fig. 12A. As illustrated in Fig. 12A, the charging plate 50 includes a plurality of electric wires 51 arranged concentrically about the placement space for the wafer 4 and a film-shaped dielectric 52, which is disposed on the electric wires 51 as illustrated in Fig. 12B.

The dielectric 52 is disposed to minimize the possibility of electric discharge when a high voltage is applied to the electric wires 51. In the present embodiment, the capture area is provided on the dielectric 52 such that the area extends over a region where the electric wires 51 are arranged. The electric wires 51 are arranged on a support 53.

The electric wires 51 are connected to the voltage source 32. When supplied with a voltage from the voltage source 32, the electric wires 51 generate electrostatic force, with which the particles 20 can be captured. The voltage source 32 may change the polarity of voltage from one electric wire 51 to another.

The electric wires 51 of the charging plate 50 do not have to be arranged concentrically about the wafer 4. As long as the electric wires 51 surround the placement space for the wafer 4, the number of electric wires 51 and the shape of the electric wires 51 are not limited to those described above. A plurality of electric wires 51 may be arranged parallel to one another in one direction (see Fig. 13) to surround the placement space for the wafer 4. Alternatively, a single long electric wire 51 may be folded many times to surround the placement space for the wafer 4.

The difference in level between the dielectric 52 and the wafer 4 can be less than or equal to 1 mm. When a gas in a space under the pattern portion 9a is replaced with another gas, the dielectric 52 can introduce the other gas to efficiently supply the gas to the space under the pattern portion 9a.

Fig. 14 illustrates another mold-side capturing unit. Like the charging plate 50, a charging plate 60 may include electric wires 61 surrounding the placement space for the mold 9, as illustrated in Fig. 14, and a film-shaped dielectric (not illustrated) that is disposed on the electric wires 61 so as to face the wafer 4. As long as the electric wires 61 surround the mold 9, the number of electric wires 61 and the shape of the electric wires 61 are not limited to those described above. A plurality of electric wires 61 may be arranged parallel to one another in one direction to surround the mold 9. Alternatively, a single long electric wire 61 may be folded many times to surround the mold 9.

The mold-side capturing unit and the wafer-side capturing unit in the present embodiment may be applied to any of the

imprint apparatuses

100, 110, 200, 300, and 400.

Other Embodiments

The term "particle 20" as used herein refers to a substance that is not intended to be related to pattern formation. Examples of the particles 20 include solid matter made of suspended dried droplets of the imprint material 4a supplied by an ink jet method, solid matter made of suspended dried droplets of the imprint material 4a supplied by a spin coating method, fine particles generated from a component included in the imprint apparatus, and dust in the imprint apparatus.

In each of the above-described configurations, the electrostatic chuck 12 is attached to the lower surface of the holding mechanism 10. The configuration is not limited to the above-described configuration. For example, a support member may be attached to the bridge surface plate 8, and the electrostatic chuck 12 and the charging plate 13 may be arranged on the support member instead of on the holding mechanism 10.

In each of the first to seventh embodiments, the charging

plates

13 and 31 are arranged such that the

capture areas

13b and 31b extend along a horizontal plane (surface of the substrate). Arrangement of the capture areas for capturing the particles 20 with electrostatic force in the present invention is not limited to the above-described arrangement. The

capture areas

13b and 31b that surround the placement space for the mold 9 and the placement space for the wafer 4, respectively, may be inclined relative to the horizontal plane or may extend vertically.

As regards the imprint material, a curable composition (also referred to as an "uncured resin") that cures by receiving curing energy is used. Examples of the curing energy include electromagnetic waves and heat. Examples of the electromagnetic waves include light whose wavelength is selected in a range of 10 nm to 1 mm, such as infrared rays, visible light, and ultraviolet rays.

The curable composition cures when irradiated with light or when heated. The curable composition that cures by light may contain at least a polymerizable compound and a photoinitiator, and may contain a non-polymerizable compound or a solvent as necessary. The non-polymerizable compound is at least one compound selected from the group consisting of a sensitizer, a hydrogen donor, an internal release agent, a surfactant, an antioxidant, and a polymer component.

The imprint material is applied in the form of a film to the wafer 4 by a spin coater or a slit coater. Alternatively, the imprint material may be applied in the form of a droplet or an island or film of connected droplets to the wafer 4 by a liquid injection head. The imprint material has a viscosity (viscosity at 25°C) that is greater than or equal to 1 mPa*s and is less than or equal to 100 mPa*s, for example.

The above-described first to eighth embodiments and other embodiments may be combined as appropriate to provide an imprint apparatus having a plurality of features.

Method of Manufacturing Article

A pattern made of the hardened material formed using the imprint apparatus is permanently used as at least part of an article or is temporarily used for manufacture of an article.

Examples of articles include electric circuit elements, optical elements, micro-electro-mechanical system (MEMS) elements, recording elements, sensors, and molds.

Examples of electric circuit elements include volatile and non-volatile semiconductor memories, such as dynamic random access memories (DRAMs), static RAMs (SRAMs), flash memories, and magnetoresistive RAMs (MRAMs), and semiconductor devices, such as large-scale integrated circuits (LSIs), charge-coupled devices (CCDs), image sensors, and field programmable gate arrays (FPGAs). Examples of molds include imprinting molds.

The pattern made of the hardened material is used as at least one component of such an article or is temporarily used as a resist mask. The resist mask is removed after etching or ion implantation in processing the wafer 4.

A method of manufacturing an article may include a step of forming a pattern on a substrate by using the imprinting apparatus, and a step of processing the substrate having the pattern. Examples of the step of processing is that etching, ion-planting, oxidization, film formation, deposition, planarization, resist stripping, dicing, bonding, packaging, and so forth.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2015-087839, filed April 22, 2015 and No. 2016-016451, filed January 29, 2016, which are hereby incorporated by reference herein in their entirety.

Claims

An imprint apparatus for forming a pattern of an imprint material on a substrate by using a mold, the apparatus comprising:
a capturing unit having a capture area for capturing a particle with electrostatic force such that the capture area surrounds a placement space for the substrate.
The apparatus according to Claim 1,
wherein the capturing unit includes a control unit configured to control a voltage to charge the capture area, and
wherein the control unit controls the voltage such that the capture area is charged with a same polarity as that of the mold.
The apparatus according to Claim 2, wherein the control unit controls the voltage such that an absolute value of potential of the capture area is greater than that of the mold.
The apparatus according to Claim 1,
wherein the capturing unit includes a control unit configured to control a voltage to charge the capture area, and
wherein the control unit controls the voltage such that the capture area is charged positively.
The apparatus according to any one of Claims 1 to 4,
wherein the capture area is a first capture area and the capturing unit is a first capturing unit, and
wherein the apparatus further includes a second capturing unit having a second capture area for capturing a particle with electrostatic force such that the second capture area surrounds a placement space for the mold.
The apparatus according to Claim 5,
wherein the first capturing unit includes a first control unit configured to control a voltage to charge the first capture area,
wherein the second capturing unit includes a second control unit configured to control a voltage to charge the second capture area, and
wherein the first and second control units charge the first and second capture areas with opposite polarities.
The apparatus according to Claim 6, wherein at least one of the first and second control units changes the voltage during an operation for forming the pattern.
The apparatus according to Claim 7, wherein at least one of the first and second control units controls the voltage such that a potential difference between the first and second capture areas spaced apart at a second distance less than a first distance is less than that between the first and second capture areas spaced apart at the first distance.
The apparatus according to any one of Claims 1 to 8, further comprising:
a replacing mechanism configured to replace a portion including the capture area having captured particles at predetermined time.
The apparatus according to any one of Claims 1 to 9, wherein the capture area extends along the substrate.
The apparatus according to any one of Claims 1 to 4, wherein the capturing unit includes an electric wire surrounding the placement space for the substrate and a dielectric disposed on the electric wire.
An imprinting method for forming a pattern of an imprint material on a substrate by using a mold, the method comprising the steps of:
(a) charging a capture area surrounding a placement space for the substrate;
(b) moving the substrate to a position at which the substrate faces the mold; and
(c) forming a pattern on the substrate,
step (a) involving capturing a particle with electrostatic force generated from the charged capture area.
The method according to Claim 12,
wherein the capture area is a first capture area,
wherein the method further includes step (d) of charging a second capture area surrounding a placement space for the mold, and step (d) is performed before step (b), and
wherein the method further includes step (e) of controlling a charged amount of at least one of the first and second capture areas to reduce electrostatic force generated from the corresponding one of the first and second capture areas, and step (e) is performed between steps (d) and (c).
A method of manufacturing an article, the method comprising the steps of:
forming a pattern on a substrate using the imprint apparatus according to any one of Claims 1 to 11; and
processing the substrate with the formed pattern.