Patent Publication Number: US-2023138973-A1

Title: Imprint apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is related to an imprint apparatus. 
     Description of the Related Art 
     Conventionally, it has been known that an overlay accuracy between a pattern already formed in a shot region of a substrate and a pattern to be newly formed deteriorates when an imprint apparatus performs an imprint process in a state in which a distortion occurs in the shot region. 
     Japanese Patent Application Laid-open No. 2017-212439 discloses an imprint apparatus which suppresses a decrease in overlay accuracy by changing a supply amount of an imprint material supplied to each region in a shot region of a substrate in accordance with a distortion in the shot region. 
     In the imprint apparatus disclosed in Japanese Patent Application Laid-open No. 2017-212439, a mold is brought into contact with an imprint material after the imprint material is supplied in different supply amounts to respective regions in a shot region of a substrate in accordance with distortion in the shot region. 
     Accordingly, the imprint material may spread to be planarized when the mold is brought into contact with the imprint material. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an imprint apparatus capable of stably forming a pattern of an imprint material according to a distortion in a shot region of a substrate. 
     The imprint apparatus according to the present invention is an imprint apparatus for forming a pattern of an imprint material on a substrate by using a mold. The imprint apparatus includes a supplying unit configured to supply the imprint material onto the substrate, an energy supplying unit configured to supply energy for increasing a degree of polymerization to the imprint material on the substrate, a moving unit configured to move at least one of the mold and the substrate, and a controller, in which the controller is configured to perform a first supplying step of supplying the imprint material onto at least a first region in a predetermined shot region on the substrate by the supplying unit, a first energy supplying step of supplying the energy to the imprint material supplied onto the first region by the energy supplying unit so as to increase the degree of polymerization of the imprint material supplied onto the first region, a moving step of moving at least one of the mold and the substrate by the moving unit such that a pattern region formed on the mold and the imprint material on the substrate are brought into contact with each other, and a second energy supplying step of supplying the energy to the imprint material supplied onto the predetermined shot region by the energy supplying unit such that the imprint material supplied onto the predetermined shot region is solidified after the pattern region and the imprint material on the substrate are brought into contact with each other. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic cross-sectional view of an imprint apparatus according to a first embodiment of the present invention. 
         FIG.  2 A  is a flowchart showing an imprint process performed by the imprint apparatus according to the first embodiment. 
         FIG.  2 B  is a flowchart showing the imprint process performed by the imprint apparatus according to the first embodiment. 
         FIG.  3 A  is an enlarged cross-sectional view of a shot region when a predetermined step in the imprint process is performed by the imprint apparatus according to the first embodiment. 
         FIG.  3 B  is an enlarged cross-sectional view of a shot region when a predetermined step in the imprint process is performed by the imprint apparatus according to the first embodiment. 
         FIG.  4 A  is a schematic cross-sectional view of an imprint apparatus according to a second embodiment of the present invention. 
         FIG.  4 B  is a partially enlarged schematic cross-sectional view of an imprint apparatus according to the second embodiment. 
         FIG.  5 A  is a flowchart showing an imprint process performed by the imprint apparatus according to the second embodiment. 
         FIG.  5 B  is a flowchart showing the imprint process performed by the imprint apparatus according to the second embodiment. 
         FIG.  6 A  is an enlarged cross-sectional view of a shot region when a predetermined step in the imprint process is performed by the imprint apparatus according to the second embodiment. 
         FIG.  6 B  is an enlarged cross-sectional view of a shot region when a predetermined step in the imprint process is performed by the imprint apparatus according to the second embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an imprint apparatus according to the present invention is described in detail with reference to the accompanying drawings. Note that the embodiments described below do not limit the structures according to the set of claims of the present application. 
     Further, although a plurality of features are described in the present embodiments, all of the plurality of features are not necessarily essential, and a plurality of features may be arbitrarily combined. 
     Furthermore, the imprint apparatus is drawn on a scale different from the actual scale in order to facilitate understanding of the imprint apparatus according to the present invention in the accompanying drawings, and the same or similar components are denoted by the same reference numerals, and redundant description is omitted. 
     In addition, hereinafter, an axis perpendicular to the substrate surface of the substrate  10  is defined as a Z-axis, and two axes perpendicular to each other in a plane parallel to the substrate surface of the substrate  10  are defined as an X-axis and a Y-axis. 
     Further, rotation directions around the X-axis, the Y-axis and the Z-axis are defined as a θX direction, a θY direction, and a θZ direction, respectively. 
     First Embodiment 
     According to a demand for miniaturization in semiconductor devices, micro electro mechanical systems (MEMS) or the like, an imprint technique of forming a pattern of an imprint material on a substrate surface by molding the imprint material on the substrate surface with a mold has attracted attention, in addition to a conventional photolithography technique. 
     By utilizing such an imprint technique, a nanoscale pattern can be formed on a substrate surface. 
     As described above, an imprint apparatus employing an imprint technique can be used to form a nanoscale pattern on a semiconductor wafer in a manufacturing process of a semiconductor device. 
     When a new pattern layer is laminated on a pattern layer already formed on the substrate surface, an accuracy of alignment between the two pattern layers is referred to as overlay accuracy which is important for making a semiconductor device to be manufactured function correctly. 
     In an imprint apparatus, a substrate is held by a substrate chuck which is polished to a very high degree of flatness so as to reduce a distortion of a substrate surface when the substrate is sucked. 
     However, there is a limit to the degree of flatness which can be achieved by polishing techniques, so that a substrate surface of the substrate may still be distorted when held by the substrate chuck due to the small amount of residual distortion in the substrate holding surface of the substrate chuck. 
     That is, a deviation in the flatness or planarity of the substrate holding surface of the substrate chuck may generate an in-plane distortion in the substrate plane to conform to the substrate holding surface of the substrate chuck. 
     When a pattern region formed on a mold is brought into contact with the imprint material supplied onto the substrate surface in which the in-plane distortion is generated in this manner, an in-plane distortion can be generated in the pattern region such that the pattern region matches the flatness of the substrate surface. 
     All of the above-described distortions become factors which degrade the overlay accuracy. 
     As described above, when the imprint material supplied onto the substrate surface and the pattern region formed in the mold are brought into contact with each other, it is required to cause the shapes of the substrate surface and the pattern region to coincide with each other in a mirror-symmetrical manner, thereby suppressing a deterioration of overlay accuracy in the imprint apparatus. 
     Further, in a case where a pattern has already been formed on the substrate surface, when the imprint material supplied onto the pattern and the pattern region formed in the mold are brought into contact with each other, the shapes of the pattern and the pattern region are required to coincide with each other. 
     Conventionally, there has been known an imprint apparatus which suppresses the deterioration of the overlay accuracy by changing a supply amount of an imprint material supplied to each region in a shot region in accordance with a distortion in the shot region on a substrate surface. 
     However, the mold is brought into contact with the imprint material after the imprint material is supplied to each region in the shot region in different supply amounts in such imprint apparatus. 
     Accordingly, the imprint material spreads to be flattened when the mold is brought into contact with the imprint material. As a result, it is difficult to suppress the deterioration in the overlay accuracy in accordance with the correction of a local distortion. 
     An object of the present invention is to provide an imprint apparatus which is advantageous particularly in overlay between a pattern of an imprint material already formed on a substrate surface and a pattern of the imprint material to be newly formed thereon, in view of such problem of the conventional technique. 
       FIG.  1    shows a schematic cross-sectional view of an imprint apparatus  1  according to a first embodiment of the present invention. 
     The imprint apparatus  1  according to the present embodiment is a lithography apparatus for forming a pattern of an imprint material on a substrate using a mold employed in a lithography process included in processes for manufacturing a device such as a semiconductor element, a liquid crystal display element, or a magnetic storage medium as an article. 
     Specifically, in the imprint apparatus  1  according to the present embodiment, an uncured imprint material supplied onto a substrate surface and a mold are brought into contact with each other (the mold is brought into contact with the imprint material on the substrate surface to perform imprinting). Thereafter, a pattern of a cured product to which a pattern of the mold has been transferred can be formed on the substrate surface by applying energy for curing to the imprint material. 
     The mold used herein is also referred to as a mold, a template, or an original. 
     In the imprint apparatus  1  according to the present embodiment, a material (a curable composition) which is cured by applying energy for curing thereto is used as the imprint material. 
     The energy for curing includes electromagnetic wave or heat. Examples of the electromagnetic wave include light having a wavelength selected from a range between 10 nm and 1 mm, specifically, infrared light, visible light and ultraviolet light. 
     In the imprint apparatus  1  according to the present embodiment, a composition which is cured by light irradiation or heating is used as the curable composition. 
     In particular, a photocurable composition which is cured by light irradiation contains at least a polymerizable compound and a photopolymerization initiator, and may further contain a non-polymerizable compound or a solvent as necessary. 
     The non-polymerizable compound used herein includes at least one selected from a group including a sensitizer, a hydrogen donor, an internal release agent, a surfactant, an antioxidant and a polymer component. 
     In the imprint apparatus  1  according to the present embodiment, the imprint material may be applied onto the substrate surface in a form of a film by a spin coater or a slit coater, or may be applied onto the substrate surface in the form of a droplet, the form of an island formed by connecting a plurality of droplets, or the form of the film by a liquid ejecting head. 
     Further, a viscosity (at 25° C.) of the imprint material used in the imprint apparatus  1  according to the present embodiment is 1 mPa·s or more and 100 mPa·s or less, for example. 
     In the imprint apparatus  1  according to the present embodiment, glass, ceramics, metal, semiconductor, resin or the like is used as a material of the substrate, and a member made of a material different from that of the substrate may be formed on the substrate surface as necessary. 
     Specifically, the substrate used in the imprint apparatus  1  according to the present embodiment includes a silicon wafer, a compound semiconductor wafer, quartz glass or the like. 
     As shown in  FIG.  1   , the imprint apparatus  1  according to the present embodiment includes a first irradiating unit  2  (an energy supplying unit), a mold holding unit  3  (an imprint head), a substrate holding unit  4  (a stage), a supplying unit  5  (a dispenser), an imaging unit  6  and a controller  7 . 
     The first irradiating unit  2  emits light  9  for curing the imprint material  14  supplied onto the substrate  10 . In other words, the first irradiating unit  2  supplies energy for increasing a degree of polymerization to the imprint material  14  supplied onto the substrate  10 . 
     The imprint apparatus  1  according to the present embodiment uses an ultraviolet-curable imprint material which is cured by being irradiated with light  9  such as ultraviolet light from the first irradiating unit  2 , as the imprint material  14 . 
     That is, the imprint apparatus  1  according to the present embodiment employs a photo-curing method as a method for curing the imprint material  14 . 
     However, the present invention is not limited thereto, and the imprint apparatus  1  according to the present embodiment may employ a heat-curing method for curing the imprint material  14  using heat as a method for curing the imprint material  14 . 
     When the heat-curing method is employed, a heating unit which applies heat (heats the imprint material  14 ) for curing the imprint material  14  is provided instead of the first irradiating unit  2 . 
     The mold holding unit  3  includes a mold chuck  11  for sucking to hold the mold  8 , and a mold moving unit  38  (a moving unit) including an actuator capable of moving the mold chuck  11  which holds the mold  8  at least in the Z direction (a vertical direction). 
     The pattern region  8   a  formed on the mold  8  and the imprint material  14  on the substrate  10  are brought into contact with each other by moving the mold chuck  11  downward (in the -Z direction) by the mold moving unit  38 . 
     Next, when the pattern region  8   a  formed on the mold  8  and the imprint material  14  on the substrate  10  are brought into contact with each other, the mold moving unit  38  is controlled by the controller  7  such that an imprint force applied to the mold  8  and the imprint material  14  on the substrate  10  becomes constant. 
     Thereafter, the imprint material  14  on the substrate  10  is cured, and the mold chuck  11  is moved upward (in the +Z direction) by the mold moving unit  38 , thereby the pattern region  8   a  formed on the mold  8  is separated (released) from the cured imprint material  14  on the substrate  10 . 
     Further, the mold holding unit  3  is provided with a recess for forming the space  13  defined (partitioned) by the partition plate  41  and the mold  8 . 
     By adjusting a pressure in the space  13 , (the pattern region  8   a  of) the mold  8  can be deformed when the pattern region  8   a  formed on the mold  8  and the imprint material  14  on the substrate  10  are brought into contact with each other or when the mold  8  is separated from the cured imprint material  14  on the substrate  10 . 
     For example, the pattern region  8   a  formed on the mold  8  and the imprint material  14  on the substrate  10  can be brought into contact with each other in a state in which the mold  8  is deformed into a convex shape toward the substrate  10  by increasing the pressure in the space  13 . 
     The substrate holding unit  4  includes a substrate chuck  16  for sucking to hold the substrate  10 , and a substrate moving unit  17  (a moving unit) including an actuator capable of moving the substrate chuck  16  which holds the substrate  10  at least in the X direction and the Y direction. 
     The substrate holding unit  4  is provided with a mirror  18  and an interferometer  19 , and a position of the substrate holding unit  4  is obtained from an optical path length measured between the mirror  18  and the interferometer  19 . 
     The position of the substrate holding unit  4  may be obtained using an encoder instead of the mirror  18  and the interferometer  19 . 
     The mold holding unit  3  which holds the mold  8  includes a posture adjusting unit for adjusting an inclination of the mold  8 , and the substrate holding unit  4  which holds the substrate  10  includes a posture adjusting unit for adjusting an inclination of the substrate  10 . 
     By correcting a relative inclination between the mold  8  and the substrate  10  using these posture adjusting units, the pattern region  8   a  formed on the mold  8  and a shot region on the substrate  10  can be made parallel to each other. 
     The relative inclination between the mold  8  and the substrate  10  may be corrected by the posture adjusting unit included in one of the mold holding unit  3  and the substrate holding unit  4 , or may be corrected by the posture adjusting units included in each of the mold holding unit  3  and the substrate holding unit  4 . 
     The supplying unit  5  supplies the imprint material  14  onto a predetermined shot region on the substrate  10 . 
     The imaging unit  6  emits light  35  to image it which has passed through the mold  8  and been reflected by the substrate  10 , thereby a contact state between the mold  8  and the imprint material on the substrate  10  is detected. 
     The controller  7  is formed by an information processing apparatus (a computer) including a CPU, a memory and the like, and integrally controls to operate each unit of the imprint apparatus  1  according to the present embodiment in accordance with a program stored in a storing unit (not illustrated). 
     Specifically, the controller  7  controls an imprint process for forming a pattern in each shot region on the substrate  10  and processes related thereto. 
     The controller  7  may be provided in the imprint apparatus  1  according to the present embodiment, or may be provided outside the imprint apparatus  1  according to the present embodiment. 
     The detecting unit  12  detects a mark (an alignment mark) formed on the mold  8  and a mark (an alignment mark) formed on the substrate  10 . 
     After obtaining a relative positional deviation between the mold  8  and the substrate  10  from a detection result of the detection unit  12 , the controller  7  can align the mold  8  and the substrate  10  by moving at least one of the mold  8  and the substrate  10 . 
     In the imprint apparatus  1  according to the present embodiment, the mold moving unit  38  relatively moves the mold  8  with respect to the substrate  10  to bring the pattern region  8   a  formed on the mold  8  and the imprint material  14  on the substrate  10  into contact with each other, but the present invention is not limited thereto. 
     For example, the pattern region  8   a  formed on the mold  8  and the imprint material  14  on the substrate  10  may be brought into contact with each other by moving the substrate chuck  16  upward (in the +Z direction) by the substrate moving unit  17 . 
     Further, the pattern region  8   a  formed on the mold  8  and the imprint material  14  on the substrate  10  may be brought into contact with each other by moving the mold chuck  11  downward by the mold moving unit  38  and moving the substrate chuck  16  upward by the substrate moving unit  17 . 
     That is, at least one of the substrate moving unit  17  and the mold moving unit  38  can be used as a moving unit which relatively moves the mold  8  and the substrate  10  in order to bring the pattern region  8   a  and the imprint material  14  into contact with each other in the imprint apparatus  1  according to the present embodiment. 
       FIG.  2 A  shows a flowchart of an operation of the imprint apparatus  1  according to the present embodiment, specifically an imprint process for forming a pattern by molding the imprint material  14  with the mold  8  in each shot region on the substrate  10 . 
     Each step in the flowchart is controlled by the controller  7 . 
     First, when the imprint process on the substrate  10  is started, the substrate  10  is conveyed into the imprint apparatus  1  according to the present embodiment (step S 101 ). 
     Specifically, in the step S 101 , the substrate  10  is conveyed into the imprint apparatus  1  according to the present embodiment via a substrate conveying mechanism (not illustrated), and then the substrate  10  is held by the substrate chuck  16  of the substrate holding unit  4 . 
     Next, a supplying step of supplying the imprint material  14  onto the substrate  10  is performed (step S 102 ). 
     Specifically, in the step S 102 , the imprint material  14  is supplied from the supplying unit  5  to a predetermined shot region (a target shot region) on the substrate  10  on which a pattern of the imprint material  14  is to be formed. 
     Next, a contacting step (a moving step) of bringing the mold  8  and the imprint material  14  on the substrate  10  into contact with each other is performed (step S 103 ). 
     Specifically, in the step S 103 , the imprint material  14  supplied onto the predetermined shot region on the substrate  10  and the pattern region  8   a  formed on the mold  8  are brought into contact with each other by bringing the mold  8  and the substrate  10  relatively close to each other. 
     Next, a relative alignment between the mold  8  and the substrate  10  is performed (step S 104 ). The alignment in the step S 104  is performed after the contacting step in the step S 103  is finished, and a pattern in the pattern region  8   a  formed on the mold  8  is sufficiently filled with the imprint material  14 . 
     Specifically, in the step S 104 , the detection unit  12  detects the mark formed on the mold  8  and the mark formed on the substrate  10 , and then the relative alignment between the mold  8  and the substrate  10  is performed based on the detection result. 
     Here, in the imprint apparatus  1  according to the present embodiment, the relative alignment between the mold  8  and the substrate  10  is performed in the step S 104 , but a correction of a distortion which occurs in the mold  8 , the substrate  10 , the imprint apparatus  1  or any combination thereof is not performed. 
     The distortion referred to herein includes the distortion of the pattern formed on the mold  8  caused by deviation in flatness of holding surfaces of the substrate chuck  16  and the mold chuck  11 , a main surface of the substrate  10 , a main surface of the mold  8  or any combination thereof. In addition, the distortion referred to herein includes an error of the pattern formed on the mold  8  and the distortion of the substrate  10 . All of these distortions affect an overlay accuracy. 
     In the imprint apparatus  1  according to the present embodiment, it is possible to correct the distortion of the pattern due to the deviation in flatness to improve the overlay accuracy by selectively increasing the degree of polymerization of the imprint material  14  supplied to a predetermined region on a shot region, as described below. 
       FIG.  2 B  shows a flowchart indicating each step included in the step of supplying the imprint material  14  in the step S 102  for correcting such distortion in the imprint apparatus  1  according to the present embodiment. 
     First, the imprint material  14  is supplied from the supplying unit  5  to a first region in a predetermined shot region on the substrate  10  based on information such as the distortion of the pattern formed on the mold  8  and the distortion of the substrate  10  as described above (step S 201 , a first supplying step). 
     Next, the imprint material  14  supplied to the first region in the step S 201  is irradiated with the light  9  from the first irradiating unit  2  so as to increase the degree of polymerization (step S 202 , a first energy supplying step). 
     Note that an irradiation amount of the light  9  here is set such that the degree of polymerization of the imprint material  14  supplied to the first region is higher than that when the imprint material  14  is supplied in the step S 201  and lower than that when the imprint material  14  is cured in the later step S 106 . 
     That is, in the step S 202 , the imprint material  14  supplied to the first region may be irradiated with the light  9  from the first irradiating unit  2  so as to increase the degree of polymerization of the imprint material  14  to an extent that the imprint material  14  is not cured. 
     In other words, the irradiation amount of the light  9  from the first irradiating unit  2  in the step S 202  may be ⅒ or less, preferably 1/100 or less, and more preferably 1/1000 or less of the irradiation amount necessary for curing the imprint material  14 . 
     Further, when a magnitude of a shearing force generated in the relative alignment between the mold  8  and the substrate  10  in the step S 104  exceeds the 10 N, there is a concern that each pattern shape collapses during the alignment to deteriorate the alignment accuracy. 
     Thus, when the light  9  is emitted from the first irradiating unit  2  in the step S 202 , the degree of polymerization of the imprint material  14  supplied to the first region may be increased such that the magnitude of the shearing force becomes 10 N or less, preferably 5 N or less, and more preferably 1 N or less. 
     In other words, assuming that the imprint material  14  is in a liquid state and a solid state when supplied in the step S 201  and cured in the step S 106 , respectively, the imprint material  14  may be brought into a gel (semi-cured) state in the step S 202 . 
     The first region to which the imprint material  14  is supplied in the step S 201  is determined based on information such as the distortion of the pattern formed on the mold  8  and the distortion of the substrate  10  due to the deviation in flatness (a determining step). 
     Specifically, the first region to which the imprint material  14  is supplied is determined based on information of the distortion obtained from positions and sizes detected in a plurality of marks formed in each of the predetermined shot region on the substrate  10  and the pattern region  8   a  on the mold  8 . 
     Next, the imprint material  14  necessary for forming a pattern is supplied from the supplying unit  5  to a second region other than the first region in the predetermined shot region on the substrate  10  (step S 203 , a second supplying step). 
     A supply amount per unit area of the imprint material  14  supplied onto the second region in the step S 203  is preferably smaller than that of the imprint material  14  supplied onto the first region in the step S 201 . 
     That is, it is possible to more effectively generate a distortion in the pattern region  8   a  as described below by setting the supply amount per unit area of the imprint material  14  in the step S 201  to be larger than that of the imprint material  14  in the step S 203 . 
     Although an example in which the imprint material  14  is supplied to each of the first region and the second region in a predetermined shot region on the substrate  10  has been described above, the present invention is not limited to this. 
     That is, the predetermined shot region on the substrate  10  may be divided into three or more regions, and the supply of the imprint material  14  and the irradiation with the light  9  may be sequentially performed according to the above-described manner. 
     Returning to  FIG.  2 A , after the relative alignment between the mold  8  and the substrate  10  is performed in the step S 104 , it is determined whether the relative positional deviation between the mold  8  and the substrate  10  falls within an allowable range (step S 105 ). 
     If the relative positional deviation between the mold  8  and the substrate  10  does not fall within the allowable range (No in the step S 105 ), the process returns to the step S 104 , and the relative alignment between the mold  8  and the substrate  10  is performed again. 
     On the other hand, when the positional deviation falls within the allowable range (Yes in the step S 105 ), the process proceeds to step S 106 . In the step S 106 , a curing step (a second energy supplying step) is performed in which the imprint material  14  supplied to the predetermined shot region on the substrate  10  is cured (solidified) by being irradiated with the light  9  from the first irradiating unit  2 . 
       FIG.  3 A  shows an enlarged cross-sectional view of the predetermined shot region to which the imprint material  14  is supplied in the step S 102 . 
     Specifically, in  FIG.  3 A , the imprint material  14   a  having a relatively high degree of polymerization in the first region and the imprint material  14   b  having a relatively low degree of polymerization in the second region are illustrated. 
     In addition, in  FIG.  3 A , a pattern which has already been formed with a distortion between the substrate  10  and the imprint material  14   a  and between the substrate  10  and the imprint material  14   b  is not illustrated. 
       FIG.  3 B  shows an enlarged cross-sectional view of the predetermined shot region in which the steps S 103  to S 106  have been performed. 
     Specifically, in  FIG.  3 B , a center position  401  of the first region and a center position  402  of the second region are shown. 
     As shown in  FIG.  3 B , a spread by being pressed by the mold  8  in the step S 103  of the imprint material  14   a  in the first region of which the degree of polymerization increases is suppressed more than that of the imprint material  14   b  in the second region. 
     Thus, the imprint material  14   a  in the first region becomes thicker than the imprint material  14   b  in the second region by performing the curing step in the step S 106 . 
     At this time, the pattern region  8   a  formed on the mold  8  is deformed so as to conform to such thickness distribution of the imprint material  14 . 
     Specifically, at the position  401 , a valley-fold (concave) bending force is applied to the pattern region  8   a , thereby a deformation in a shrinking direction occurs in the pattern surface. 
     On the other hand, at the position  402 , a mountain-fold (convex) bending force is applied to the pattern region  8   a , thereby a deformation in an extending direction occurs in the pattern surface. 
     As described above, it is possible to generate a distortion in the pattern surface by generating a deviation in flatness in the pattern region  8   a  so as to conform to the thickness distribution of the imprint material  14  in the imprint apparatus  1  according to the present embodiment. 
     Returning to  FIG.  2 A , after the curing process in the step S 106  is performed, a mold releasing step of separating the mold  8  and the imprint material  14  on the substrate  10  from each other is performed (step S 107 ). 
     Then, it is determined whether or not the process including the steps S 102  to S 107  has been completed for all of designated shot regions on the substrate  10  (step S 108 ). 
     If the process has not been completed for all of the designated shot regions on the substrate  10  (No in the step S 108 ), the process returns to the step S 102  to continue the process. 
     On the other hand, when the process has been completed for all of the designated shot regions on the substrate  10  (Yes in the step S 108 ), the process proceeds to step S 109 , the substrate  10  is carried-out from the imprint apparatus  1  according to the present embodiment, and the imprint process for the substrate  10  is ended. 
     As described above, in the imprint apparatus  1  according to the present embodiment, the degree of polymerization of the imprint material  14  in the first region in the shot region on the substrate  10  is increased in the supplying step based on information about a distortion of the pattern formed on the mold  8 , a distortion of the substrate  10  and the like due to a deviation in flatness. 
     In other words, the first region in the shot region is determined based on a difference between respective shapes of the pattern region  8   a  formed on the mold  8  and a predetermined shot region on the substrate  10 , and the degree of polymerization of the imprint material  14  in the first region is increased. 
     As a result, an in-plane distortion is locally generated in the pattern region  8   a  of the mold  8  when the curing step is performed, so that an overlay accuracy can be improved. 
     Second Embodiment 
       FIG.  4 A  shows a schematic cross-sectional view of an imprint apparatus  71  according to a second embodiment of the present invention. Note that the imprint apparatus  71  according to the present embodiment has the same structure as the imprint apparatus  1  according to the first embodiment except that a second irradiating unit  60  is newly provided. Thus, the same members are denoted by the same reference numerals, and description thereof will be omitted. 
     Further,  FIG.  4 B  shows a schematic cross-sectional view of the second irradiating unit  60  (an energy supplying unit) provided in the imprint apparatus  71  according to the second embodiment. 
     As shown in  FIG.  4 B , the second irradiating unit  60  includes a light source  51 , a light modulating element  53  (a spatial light modulating element), an optical element  54   a  and an optical element  54   b , and can irradiate a predetermined region on the substrate  10  with light  50 . 
     That is, the first irradiating unit  2  can irradiate an entire predetermined shot region on the substrate  10  with the light  9 , whereas the second irradiating unit  60  can irradiate a predetermined region in the predetermined shot region on the substrate  10  with the light  50  in the imprint apparatus  71  according to the present embodiment. 
     The light source  51  is selected from light sources, such as a lamp, a laser diode or an LED, capable of obtaining an output necessary to emit the light  50  with a wavelength which causes the imprint material  14  on the substrate  10  to undergo a polymerization reaction (increase the degree of polymerization) so as to have a predetermined viscosity. 
     The light  50  emitted from the light source  51  passes through the optical elements  54   a  and is then guided to the light modulating element  53 . 
     The light modulating element  53  is formed by a digital micromirror device (DMD). 
     By arranging the light modulating element  53  between the light source  51   and the substrate  10  to adjust angles of respective micromirrors, it is possible to arbitrarily control (set) a position and a size of an irradiated range of the light  50  on the substrate  10 . 
     That is, a magnification of the light  50  is adjusted by the light modulating element  53  such that the light  50  is irradiated (projected) onto a predetermined region on the substrate  10  after passing through the optical device  54   b . 
     In addition, an irradiating time of the light  50  onto the predetermined region on the substrate  10  can be arbitrarily controlled by changing the angle of each micromirror with time. 
     Note that the light modulating element  53  is not limited to a digital micromirror device, and an element such as a liquid crystal display (LCD) device or a liquid crystal on silicon (LCOS) device may be used. 
     In the imprint apparatus  71  according to the present embodiment, an overlay accuracy is improved by selectively increasing the degree of polymerization of the imprint material  14  on the substrate  10  using the light modulating element  53  based on information about a distortion of the pattern formed on the mold  8  and a distortion of the substrate  10  and the like due to a deviation in flatness. 
       FIG.  5 A  shows a flowchart of an operation in the imprint apparatus  71  according to the present embodiment, specifically an imprint process for forming a pattern by molding the imprint material  14  with the mold  8  in each shot region on the substrate  10 . 
     Note that the flowchart in the imprint apparatus  71  according to the present embodiment is identical to that in the imprint apparatus  1  according to the first embodiment except that a step S 702  is performed instead of the step S 102  in the supplying step. Thus, only the step S 702  will be described below. 
       FIG.  5 B  shows a flowchart indicating each step included in the supplying step of supplying the imprint material  14  in the step S 702  in the imprint apparatus  71  according to the present embodiment. 
     First, the supplying unit  5  supplies the imprint material  14  over an entire predetermined shot region on the substrate  10  (step S 801 ). 
     In the step S 801 , since the imprint material  14  is supplied over the entire predetermined shot region on the substrate  10 , the imprint material  14  may be supplied in a film form onto the substrate  10  using a spin coater or a slit coater instead of the supplying unit  5 . 
     Next, each region in the predetermined shot region on the substrate  10  is irradiated with the light  50  from the second irradiating unit  60  so as to change a light irradiating time in accordance with a distortion of the pattern formed on the mold  8 , a distortion of the substrate  10  and the like due to a deviation in flatness (step S 802 ). 
       FIG.  6 A  shows an enlarged cross-sectional view of the predetermined shot region irradiated with the light  50  in the step S 802 . 
     Specifically,  FIG.  6 A  illustrates an imprint material  14   a  having a relatively highest degree of polymerization, an imprint material  14   b  having a relatively second highest degree of polymerization, and an imprint material  14   c  having a relatively lowest degree of polymerization. 
     In addition, in  FIG.  6 A , a pattern which has been already formed with a distortion between the substrate  10  and the imprint material  14   a , between the substrate  10  and the imprint material  14   b , and between the substrate  10  and the imprint material  14   c  is not illustrated. 
     The degree of polymerization of the imprint material  14  changes according to a light amount of light with which the imprint material  14  is irradiated. 
     Accordingly, the degree of polymerization of the imprint material  14  in each region is adjusted by changing the irradiating time of the light  50  in the imprint apparatus  71  according to the present embodiment. 
     That is, in  FIG.  6 A , the irradiating time of the light  50  to the imprint material  14   a  is relatively the longest, the irradiating time of the light  50  to the imprint material  14   b   is relatively the second longest, and the irradiating time of the light  50  to the imprint material  14   c  is relatively the shortest. 
       FIG.  6 B  shows an enlarged cross-sectional view of the predetermined shot region in which the steps S 103  to S 106  have been performed. 
     Specifically,  FIG.  6 B  illustrates a center position  401  of a region to which the imprint material  14   b  is supplied, a center position  402  of a region to which the imprint material  14   c  is supplied, and a center position  403  of a region to which the imprint material  14   a  is supplied. 
     As shown in  FIG.  6 B , a spread by being pressed by the mold  8  in the step  103  is suppressed in the order of materials having a relatively high degree of polymerization, namely in the order of the imprint material  14   a , the imprint material  14   b  and the imprint material  14   c . 
     Accordingly, thicknesses of the imprint material  14   a , the imprint material  14   b  and the imprint material  14   c  increase in this order, by performing the curing process in the step S 106 . 
     At this time, the pattern region  8   a  formed on the mold  8  is deformed so as to conform to such thickness distribution of the imprint material  14 . 
     Specifically, at the position  401 , a valley-fold (concave) bending force is applied to the pattern region  8   a , thereby a deformation in a shrinking direction occurs in the pattern surface. 
     Further, at the position  403 , a valley-fold (concave) bending force is applied to the pattern region  8   a  more strongly than at the position  401 , thereby the deformation in the shrinking direction occurs in the pattern surface more largely than at the position  401 . 
     On the other hand, at the position  402 , a mountain-fold (convex) bending force is applied to the pattern region  8   a , thereby a deformation in an extending direction occurs in the pattern surface. 
     As described above, it is possible to generate a distortion in the pattern surface by generating a deviation in flatness so as to conform to the thickness distribution of the imprint material  14  in the pattern region  8   a  in the imprint apparatus  71  according to the present embodiment. 
     In the above description, the irradiating times of the light  50  for the imprint material  14   a , the imprint material  14   b  and the imprint material  14   c  are different from each other, but the present invention is not limited thereto. 
     That is, the irradiating times of the light  50  for the imprint material  14  supplied to two regions in a predetermined shot region on the substrate  10  may be made different from each other. 
     Further, the irradiating times of the light  50  for the imprint material  14  supplied to four or more regions in a predetermined shot region on the substrate  10  may be made different from each other. 
     As described above, in the imprint apparatus  1  according to the present embodiment, the degree of polymerization of the imprint material  14  is changed in each region in a shot region on the substrate  10  in the supplying step based on information about a distortion of the pattern formed on the mold  8  and a distortion of the substrate  10  and the like due to a deviation in flatness. 
     In other words, based on a difference between respective shapes of the pattern region  8   a  formed on the mold  8  and a predetermined shot region on the substrate  10 , the degree of polymerization of the imprint material  14  in each region in the predetermined shot region is made different from each other. 
     As a result, an in-plane distortion is locally generated in the pattern region  8   a  on the mold  8  when the curing step is performed, thereby an overlay accuracy can be improved. 
     Note that a timing of irradiation with the light  50  in the imprint apparatus  71  according to the present embodiment is not limited to the supplying step in the step S 702 , and may be arbitrarily set between the contacting step in the step S  103  and the curing step in the step S 106 . 
     That is, for example, the degree of polymerization of the imprint material  14  in a predetermined region may be increased by irradiating the imprint material  14  with the light  50  when the imprint material  14  has a desired thickness during the contacting step in the step S 103 . 
     According to the present invention, it is possible to provide an imprint apparatus which is particularly advantageous for an overlay between a pattern of an imprint material already formed on a substrate and a pattern of the imprint material to be newly formed thereon. 
     In other words, according to the present invention, it is possible to provide an imprint apparatus capable of forming a pattern of an imprint material stably in accordance with a distortion in a shot region on a substrate. 
     Article Manufacturing Method 
     A pattern of a cured product formed by using the imprint apparatus according to the present invention is used permanently in at least a part of various articles or temporarily when manufacturing various articles. 
     Examples of the article include an electric circuit element, an optical element, a MEMS, a recording element, a sensor and a mold. 
     Further, examples of the electric circuit element include volatile or nonvolatile semiconductor memories such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory and a magnetoresistive random access memory (MRAM), and semiconductor elements such as a large scale integration (LSI), a charge coupled device (CCD), an image sensor and a field programmable gate array (FPGA). 
     Furthermore, an example of the mold includes a mold for imprinting. 
     The pattern of the cured product formed by using the imprint apparatus according to the present invention is used as it is as a constituent member of at least a part of the above-described article. 
     Alternatively, the pattern of the cured product is temporarily used as a resist mask, and the resist mask is removed after etching, ion implantation or the like is performed in a step for processing a substrate. 
     Although preferred embodiments have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the gist of the present invention. 
     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. 2021-180305, filed Nov. 4, 2021, which is hereby incorporated by reference herein in its entirety.