JP6333035B2 - Mold, imprint apparatus, imprint method, and article manufacturing method - Google Patents

Description

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

  The demand for miniaturization of magnetic storage media, semiconductor devices, MEMS, etc. has progressed, and in addition to conventional photolithography technology, photocuring of uncured resin (resist), for example, UV curable resin, supplied on a substrate (wafer) Attention has been focused on a microfabrication technique for forming a pattern on a substrate by forming a functional resin with a mold (mold, mask). This technique is also called an imprint technique, and can form a fine structure on the order of several nanometers on a substrate. For example, one of the imprint techniques is a photocuring method. In an imprint apparatus employing this photocuring method, first, uncured resin is supplied to a pattern formation region on a substrate. Next, the resin on the substrate and the mold on which the pattern is formed are brought into contact (imprinted). Then, the resin is cured by irradiating light while the resin and the mold are in contact with each other. By increasing the distance between the substrate and the mold (stripping the mold from the cured resin), a resin pattern is formed on the substrate.

  As such an imprint apparatus, an apparatus using jet and flash type imprint lithography (hereinafter referred to as “JFIL”) based on a mass production apparatus such as a semiconductor device is known. Patent Document 1 discloses an imprint method based on the JFIL method. Specifically, an ultraviolet curable resin is applied to each pattern formation region by an application mechanism such as an inkjet nozzle, and then a mold on which a device pattern is drawn is imprinted. When the ultraviolet curable resin has sufficiently penetrated into the pattern on the mold, the ultraviolet photosensitive resin is cured by irradiating the ultraviolet ray, and the mold is separated and released. The JFIL-type imprint operation is performed in a step-and-repeat manner like an optical exposure apparatus because the area of a shot to be stamped once is limited.

JP 2010-123985 A

  Recently, in order to improve the degree of integration and cost of semiconductor memory, mass production of memory devices having a 3D structure represented by BiCS (Bit Cost Scalable) and TCAT (Terbit Cell Array Transistor) has been studied. Since the contact holes and the like required for these device structures cannot be made very small and cannot be densely packed, it is necessary to greatly increase the number of stacked layers to achieve high integration.

  However, if the number of stacked layers is increased, the ratio of the depth to the hole diameter (aspect ratio) increases, making processing difficult. In addition, since the area of the region where the pattern is formed is small, the stamping force is small. For mass production, it is necessary to reduce the resin filling time and release force. At the same time, in order to suppress unevenness of the residual film (RLT: Residual Layer Thickness) and to improve the variation in the hole diameter after etching, it is also necessary to ensure a uniform and sufficient stamping force at the time of pattern stamping. The conventional techniques as described above cannot meet the needs for forming such contact holes. Specifically, even if the stamping force can be secured, the conventional JFIL method requires a large release force.

  The present invention has been made in view of such a situation.For example, a mold effective for securing a uniform and sufficient stamping force at the time of pattern stamping while reducing the resin filling time and the release force. The purpose is to provide.

In order to solve the above-mentioned problems, the present invention is an imprint method in which an uncured imprint material on a substrate is molded with a mold, and a pattern of the imprint material is formed on the substrate. And a second region having a mold surface at a position between the bottom surface of the concave portion of the concave-convex pattern and the end surface of the convex portion, and an uncured imprint material and the second region A step of bringing the mold and the substrate closer until the surface of the mold in the region contacts, the uncured imprint material in contact with the surface of the mold in the first region, and the surface of the mold in the second region And a step of curing the uncured imprint material .

  According to the present invention, for example, it is possible to provide a mold or the like effective in ensuring a uniform and sufficient stamping force during pattern stamping while reducing the resin filling time and the release force.

It is a figure which shows the structure of the imprint apparatus which concerns on one Embodiment of this invention. It is a figure which shows the specific example of the pattern layout of the mold which concerns on one Embodiment. It is sectional drawing in A-A 'of the mold shown in FIG. It is a figure which shows the imprint method in one Embodiment. It is sectional drawing at the time of stamping the mold which concerns on one Embodiment to resin. It is a figure which shows the drive sequence of the imprint head in one Embodiment. It is a figure which shows the case where a particle is inserted | pinched between the molds concerning one Embodiment. It is a figure which shows the drive sequence of the imprint head in FIG. It is a figure which shows the state of the board | substrate at the time of stamping of other embodiment, and a mold.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  First, an imprint apparatus to which a mold according to an embodiment of the present invention can be applied will be described. FIG. 1 is a diagram illustrating a configuration of an imprint apparatus to which a mold according to an embodiment of the present invention is applied. The imprint apparatus includes a mold 1, a substrate 2, a main body surface plate 101, a substrate stage 102, an imprint head 103, a reflection mirror 104, an alignment illumination system 105, and an ultraviolet light source 106. The imprint head 103 moves the mold 1 closer to the substrate 2 (Z axis) and tilts the mold 1 relative to the substrate 2 (ωx (rotation around the X axis), ωy (rotation around the Y axis)). The mold 1 is held. The ultraviolet light source 106 irradiates ultraviolet rays for curing the resin (ultraviolet curable resin, imprint material) in the horizontal direction, and the reflection mirror 104 reflects the irradiated light in the vertical direction toward the substrate. Here, the reflection mirror 104 has a characteristic of reflecting the wavelength band of the exposure light but transmitting the wavelength band of the alignment measurement light having a longer wavelength than the exposure light. The alignment illumination system 105 measures an error of the relative position shift between the mold 1 and the substrate 2 using the alignment marks formed on the mold 1 and the substrate 2. Further, the result is reflected on the control position of the substrate stage 102 and moved so that the relative position between the mold and the substrate is eliminated. The substrate stage 102 holds the substrate by suction on a substrate chuck (not shown) and moves the substrate 2 so that the pattern transfer region of the mold 1 is located in a predetermined region on the substrate 2. The substrate stage 102, the imprint head 103, the reflection mirror 104, and the alignment illumination system 105 are fixedly held on the main body surface plate 101.

  Next, the configuration of the mold according to the present embodiment will be described with reference to FIGS. FIG. 2 is a diagram illustrating an example of a pattern layout of the mold 1 according to the present embodiment. 3 is a cross-sectional view taken along line A-A ′ of the mold 1 in FIG. 2. The mold 1 according to the present embodiment has a pattern surface, and a part of the pattern surface has a region called a mesa 201 in which an uneven pattern to be transferred to a substrate is formed. The mesa 201 is an area where a pattern formed on the mold by one imprint is transferred onto the substrate. The mesa 201 is formed so as to protrude to the substrate side of several tens of μm with respect to the area other than the surrounding shot. In the mold 1 of the present embodiment, as shown in FIGS. 2 and 3, in addition to the pattern region (first region) S <b> 1 having unevenness in the mesa 201 region, the bottom surface of the concave portion and the end surface of the convex portion The blank area | region (2nd area | region) S2 which has the height of between is provided. The blank area S2 is an area where a pattern is not transferred by this mold, such as a peripheral circuit portion. For this reason, since the uneven | corrugated pattern is not formed in blank area | region S2, it can be made into a flat surface. By providing such a blank region S2, when the mold 1 is stamped, even if the convex portion is depressed, the blank region S2 is stopped, and the bottom portion of the concave portion is not depressed. Thereby, resin filling time and mold release force can be reduced. In addition, by providing the blank region S2, the density of the pattern (the density of the protrusions with respect to the entire mesa) and the stamping area (the area of the protrusions) are small, such as when forming a small number of contact holes relative to the size of the mesa region Even when the mold 1 is stamped, the blank area S2 can be sufficiently pressed. For this reason, a capillary force between the mold and the substrate can be applied, and a uniform and sufficient stamping force can be applied.

  Here, a specific example of the pattern arranged in the pattern area S1 will be described in more detail. Here, as a specific example when the pattern density is low, an example in which a contact hole is formed as shown in FIG. In such a contact hole pattern, the area of the projecting imprint pattern is extremely small compared to the area of the entire mesa region (shot region). Thus, as the pattern density is smaller, it is more difficult to apply the capillary force between the mold 1 and the substrate when the mold 1 is impressed than when the pattern density is large. For example, if the pattern area of the protrusions in the pattern region (the area of the tip surface) is 3% or less with respect to the total area of the pattern region and the blank region, the capillary force between the mold and the substrate is very small. In such a case, if the mold 1 according to the present embodiment is applied, not only the pattern region S1 but also the blank region S2 can be sufficiently pressed. For this reason, the capillary force that is insufficient in the pattern region can be compensated by the capillary force in the blank region, and the effect is very great.

  As shown in FIG. 3, the mold 1 has a chromium film 301 formed on a mold region (for example, a surface on the substrate side) other than the mesa 201 region and a mesa side surface. The chrome film 301 prevents the resin applied in a place other than the target shot area (outside the angle of view) from being cured when the substrate is exposed by irradiating ultraviolet rays from the opposite side of the pattern forming surface of the mold during pattern transfer. It is for shading. Note that no chromium film is formed in the blank region. Further, the light shielding film for shielding ultraviolet rays is not limited to the chromium film 301, and a film of another substance may be formed.

  S2a to S2c shown in FIG. 3 are the blank region surfaces described in FIG. 2, and are formed such that the height of the mold 1 from the outside of the mesa 201 region is h1. S1a and S1b shown in FIG. 3 are the end surface (tip surface) of the convex portion and the bottom surface of the concave portion in the pattern region, respectively, and are formed so that the height from the outside of the mesa 201 region of the mold 1 is h2 and h3. Yes. Here, the height h1 of the blank region S2 is a height between the height h3 of the bottom surface of the concave portion and the height h2 of the end surface (tip surface) of the convex portion. Note that the height h1 of the blank region S2 is preferably determined according to the pattern density, the thickness of the mold or the substrate, and the like. Moreover, although the height from the mesa 201 area | region was used as height h2 of this blank area | region S2, it is not restricted to this. For example, you may use the height from the end surface of a convex part in a pattern area | region, or a board | substrate.

  In the present embodiment, the pattern formed on the mold is a contact hole pattern, but the present invention is not limited to this. When the imprint area for the resin applied to the substrate is smaller than the shot area, the pattern formed on the mold may be a line-and-space pattern. For example, consider a case where the pattern area does not exceed 3% of the shot area and 97% or more is a blank area. The blank area S2 is desirably arranged so as to be divided into small portions around the pattern area S1 in order to make the stamping force uniform. The pattern density in the pattern region S1 and the thickness (hardness) of the mold and the substrate can be adjusted. Further, the blank region S2 is arranged for the purpose of obtaining a capillary force acting between the mold and the resin applied to the substrate. For this reason, a pattern such as an alignment mark used for alignment with the substrate may be arranged in the blank region S2.

  Next, an imprint method using the above-described imprint apparatus and mold will be described with reference to FIGS. FIG. 4 is a diagram illustrating an imprint method according to an embodiment. The mold 1 is provided with a hole pattern 401 for forming a hole between the substrate layers. In addition, the hole between board | substrate layers may be penetrated and does not need to penetrate. In the imprint method according to the present embodiment, as shown in FIG. 4A, the resin 3 is applied to the substrate 2 in advance by a spin coater or the like (procedure 1). The applied uncured resin 3 generally has a thickness of several tens of nanometers. As shown in FIG. 4B, the mold 1 is brought into contact with the resin 3 on the substrate 2, and ultraviolet rays are irradiated from the surface opposite to the pattern surface of the mold in a state where the hole pattern 401 and the resin 3 are in contact with each other. Resin 3 is cured (procedure 2). After the resin 3 is cured, the mold 1 can be released from the cured resin 3 (procedure 3) by increasing the distance between the mold 1 and the substrate 2 as shown in FIG. 4C.

  Furthermore, the state of the mold 1 and the resin 3 in the procedure 2 described above will be described in more detail. FIG. 5 is a cross-sectional view showing a state when the mold 1 is stamped on the resin 3. According to the mold 1 in the present embodiment, the mesa region that protrudes several tens of μm from the periphery reflecting the shot size has a height h2 that is lower than the pattern region and the pattern region (in the direction in which the mold is thin). Now, a blank area of h1 is arranged. For this reason, the hole pattern 401 in contact with the resin 3 is only the tip (h2-h1) of the convex portion of the pattern. On the other hand, the thickness of the resin 3 that has been spin-coated on the substrate in advance is made to substantially coincide with the above-described height difference (h2−h1) of the mold region, so that a desired through-hole is formed in the resin 3 on the substrate. Can be imprinted. The resin 3 is a layer of several tens of nm level previously applied to the substrate with a spin coater, and a process layer (inside the substrate 2) (not shown) underneath is chemically planarized. When the mold 1 is brought closer to the substrate 2 at the time of imprinting, a convex portion of the pattern of a part of the pattern region S1 is recessed into the resin 3 with a slight force. When a part of the blank area S2 comes into contact with the resin 3 on the substrate 2, a suction force is generated between the blank area S2 and the resin, and adsorption of the entire blank area S2 and the resin 3 is achieved.

  Thus, the mold 1 according to the present embodiment is provided with the blank region S2 having a height between the bottom surface of the concave portion of the pattern and the end surface of the convex portion, in addition to the pattern region S1 having the uneven pattern. The tip (h2-h1) of the convex portion in the pattern region S1 is in contact with the resin. And resin is not filled to the bottom face of a recessed part. Thereby, uniform and sufficient stamping force can be ensured at the time of pattern stamping while reducing the resin filling time and the release force.

  Temporarily, when not providing blank area | region S2 like the mold 1 which concerns on this embodiment, capillary force cannot fully work between a mold and a board | substrate, and uniform and sufficient stamping force cannot be ensured. there is a possibility. At this time, when there is a local undulation of the substrate or an imbalance of the imprinting force controlled on the imprint head side, unevenness occurs in the residual film (RLT) at each local area in the shot, and the contact hole There may be variations in diameter. In order to maintain stable residual film (RLT) uniformity for hole pattern formation, it is necessary to make the contact hole stamping force uniform. The shape of the mold surface at the time of imprinting and the shape of the substrate surface in the region to be imprinted (Z axis / (ωx, ωy) direction) must be imitated. On the other hand, according to the present invention, the blank area S2 can compensate for the capillary force that is insufficient only by the pattern area S1. That is, in the mold 1 according to the present embodiment, the blank region S2 is formed in the mesa of the mold 1, and a uniform stamping force is applied to the pattern region S1 by using the capillary force between the mold 1 and the substrate 2 acting on the blank region S2. Can be applied.

  In this embodiment, the pattern layout of the mold has a shape suitable for sequential imprinting for each shot. However, the mesa 201 region shown in FIG. 2 is substantially a plurality of shots, a part including the peripheral portion of the substrate, or the entire substrate surface. The present invention can also be applied to imprints including That is, if the JFIL method is used when the mold 1 is released, the entire shot area is filled with resin, whereas the resin is not filled up to the bottom surface S1b of the recess in the pattern area. For this reason, it is possible to release the mold without increasing the release force, and this method has good affinity for large screen imprint. Therefore, you may apply this invention to the mold of the imprint apparatus using the system which performs the batch imprint to a board | substrate. As described above, the imprint apparatus can not only sequentially transfer a pattern to a plurality of shot areas on a substrate by imprinting but also transfer the pattern by imprinting at a time.

  Next, details of the imprint method using the mold according to the present embodiment will be described. FIG. 6 is a diagram illustrating a driving sequence for each shot of the imprint head 103 of the imprint apparatus according to the embodiment. The horizontal axis in FIG. 6 represents time, and the horizontal axis represents the distance between the pattern surface of the mold 1 and the surface of the substrate 2 (the height of the mold 1 with respect to the substrate 2). The position of the pattern surface of the mold 1 held by the imprint head 103 is positioned at the Upplane position that is sufficiently high with respect to the resin coating surface of the substrate 2 to avoid contact with the substrate 2 before imprinting. The In this state, the substrate stage 102 can move for a long stroke, and step driving to adjacent shots and the like is performed at the height of the mold 1 (for example, about 100 to 200 μm from the substrate surface to the pattern surface of the mold 1). (T1). When the step drive to the imprint target shot is completed, the imprint head 103 is lowered toward the substrate 2. The imprint head 103 is positioned (t1 to t2) at a height (Prox alignment, for example, 10 to 30 μm) at which the alignment illumination system 105 can measure the displacement of the relative position between the substrate 2 and the mold 1. Alignment measurement is performed by a method such as die-by-die alignment or global alignment, and correction driving based on the measurement value is completed (t2 to t3). Thereafter, the mold 1 is further lowered to a height (Zm = Zw) at which the blank region surfaces S2a to S2c of the mold 1 and the surface of the resin 3 applied to the substrate 2 come into contact. In this process, the convex portion end surface S1a of the pattern region S1 of the mold 1 and the surface of the resin 3 on the substrate 2 come into contact with each other, and the resin 3 fills a part of the concave portion of the pattern region S1. Further, when the mold 1 and the substrate 2 are not in a parallel relationship, the blank region surfaces S2a to S2c and the surface of the resin 3 are collimated in a descending process (t3 to t4). At t5, the blank area surfaces S2a to S2c of the mold 1 coincide with the surface of the resin 3 of the substrate 2. However, since the resin 3 is a fluid, the resin 3 starts to flow toward the pattern region S1 from directly below the blank region surfaces S2a to S2c (t5 to t6) if the state in which the resin 3 is kept in contact is maintained. For this reason, it is necessary to manage the optimum imprint duration time for the imprint time Ti. The stamp duration time is determined based on at least the viscosity of the resin 3, the Young's modulus of the mold / substrate, the allowable value of unevenness of the remaining film (RLT), and the ratio of the pattern area / blank area mesa area. t6 to t7 are exposure times, and ultraviolet rays corresponding to the sensitivity of the resin are irradiated from the ultraviolet light source 106, the resin is cured in a state where the pattern region S1 and the resin 3 are in contact with each other, and formed into a pattern shape. When the ultraviolet irradiation is completed (t7), the imprint head 103 is pulled away to the Upplane position, and the mold 1 is released from the substrate 2 (t7 to t8).

  In the above-described method, the operation of the imprint apparatus when particles are present between the mold and the substrate will be described with reference to FIGS. FIG. 7 is a diagram illustrating a case where particles (701, 702) are sandwiched between the mold 1 and the substrate 2 in the imprint apparatus according to the embodiment. When there is a particle 702 in the blank area S2, a larger amount of driving thrust is required than when the imprint head 103 is lowered to the target height (Zm = Zw) as compared with the normal imprinting. Can recognize the presence of particles. On the other hand, when there are particles 701 in the pattern area S1, there are cases where the presence of particles can be recognized in the same manner as the blank area S2 in contact with the pattern, and cases where the particle 701 enters the gap between the patterns and cannot be recognized. In the latter case, there is a possibility that the shot to which particles are attached may become defective, but the mold 1 is not damaged so as to be damaged. In such a case, maintenance such as periodic wet cleaning is required when managing the mold 1. On the other hand, in the former case, the pattern of the mold 1 may be destroyed. Below, the method of protecting a mold with the imprint method which concerns on one Embodiment of this invention in such a case is demonstrated.

  FIG. 8 shows each shot of the imprint head 103 that operates to recognize and protect the mold 1 when the particles (701, 702) are sandwiched between the mold 1 and the substrate 2 as shown in FIG. It is a figure which shows the drive sequence. The particle size and material of particles adhering to the mold 1 and the substrate 2 are various, but those made of metal or silicon compound may destroy the pattern of the mold 1 when it interferes with the pattern of the mold 1 at the time of stamping. . Most particles with a particle size detect an abnormal thrust by monitoring the current value of the imprint head 103 when the mold is lowered from the height (Prox alignment) at which the displacement of the relative position between the substrate and the mold is measured. (T3 to t4). The imprint head 103 that has detected an abnormal thrust (contact at a position higher than the substrate surface) immediately drives to a sufficient height (Upplane) where positional interference between the mold 1 and the substrate 2 does not occur to protect the mold. At that time, the mold driving is temporarily stopped at a minute gap that becomes an intermediate position such as the Prox alignment position in the middle of returning to Upplane. Then, by performing exposure processing on the shot (t6e to t7e), it is possible to form a uniform resin film on the substrate in order to stabilize the etching of the substrate 2 while the shot is a defective shot.

  In the present embodiment, the parallelism between the mold 1 and the surface of the substrate 2 that is attracted and fixed to the substrate chuck is maintained by bending the mold 1, but the present invention is not limited to this. The substrate chuck may be provided with a mechanism for weakening the adsorption pressure (adsorption force) so that the substrate follows the surface shape of the mold. Specifically, an adsorption pressure adjusting unit 902 as shown in FIG. 9 may be provided. According to this configuration, it is possible to loosen the adsorption pressure (adsorption force) of the substrate chuck 901 in the area to be imprinted at the time of imprinting, to float the substrate 2 and to follow the shape of the mold 1, and to maintain the parallelism between the two. can do. After the resin on the substrate is filled in the blank area S2, after the resin 3 is cured, the adsorption pressure of the substrate chuck 901 is increased again, the substrate 2 is adsorbed, and the mold 3 is cured from the resin 3 Pull apart (release). According to this method, even if the stamping force for each contact hole is not uniform, the flatness of the mold and the flatness of the substrate remain, the uniformity of the residual film (RLT) for each contact hole cannot be maintained. As a result, occurrence of variations in hole diameter after etching can be suppressed.

If a function for controlling the position between the mold and the substrate of the imprint apparatus (control in the Z-axis / (ωx, ωy) direction) is provided, a pattern with a small imprint imprint area using a contact hole layer as an example The remaining film (RLT) uniformity can be easily ensured.
Further, the mold according to the present embodiment is not limited to the above-described imprint method, and can also be used when an ultraviolet curable resin is applied for each shot to an imprint target shot on the substrate. .
In the above embodiment, the chromium film 301 is formed in an area other than the pattern area formed on the mold 1 to shield the resin applied to the area other than the target shot area from being cured. However, a light shielding member that shields light for curing the resin may be provided in the imprint apparatus. What is necessary is just to determine an illumination area | region so that the predetermined area | region on a board | substrate may be irradiated using the light-shielding member in an imprint apparatus.

(Product manufacturing method)
In addition, the manufacturing method of the device (semiconductor integrated circuit element, liquid crystal display element, etc.) as the article described above is a process of forming a pattern on a substrate (wafer, glass plate, film substrate) using the above-described imprint apparatus. including. Furthermore, the manufacturing method may include a step of etching the substrate on which the pattern is formed. In the case of manufacturing other articles such as patterned media (recording media) and optical elements, the manufacturing method may include other processes for processing a substrate on which a pattern is formed instead of etching. The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

1 Mold S1 Pattern area (first area)
S2 Blank area (second area)

Claims (7)

An imprint method of forming an uncured imprint material on a substrate with a mold and forming a pattern of the imprint material on the substrate,
The mold is
A first region in which an uneven pattern is formed;
A second region having the surface of the mold at a position between the bottom surface of the concave portion of the concave-convex pattern and the end surface of the convex portion,
Bringing the mold and the substrate closer until the uncured imprint material and the surface of the mold in the second region contact each other ;
Curing the uncured imprint material in contact with the surface of the mold in the first region and the uncured imprint material in contact with the surface of the mold in the second region. A characteristic imprint method. The pattern area of the convex portion in the first region of the mold is 3% or less with respect to the total area of the first region and the second region. Imprint method. 3. The imprint method according to claim 1, wherein the second region of the mold has a shape different from that of the uneven pattern formed in the first region. 4. 4. The imprint method according to claim 1, wherein an uneven pattern is not formed in the second region of the mold. 5. An alignment mark used for alignment with the substrate is formed in the second region of the mold,
The imprint method according to claim 1, further comprising a step of aligning the mold and the substrate using the alignment mark . A light-shielding film that blocks light for curing the imprint material is formed on the surface of the mold around the first region of the mold, and the light-shielding film is not formed in the second region. The imprint method according to any one of claims 1 to 5 . Forming an imprint material pattern on a substrate using the imprint method according to any one of claims 1 to 5 ;
Processing the substrate on which the pattern is formed in the step;
A method for producing an article comprising:

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