JP6538592B2 - Pattern formation method - Google Patents

Description

  Embodiments of the present invention relate to a pattern formation method.

  NIL (Nano-Imprint Lithography) is a patterning method in which a template is in direct contact with a resist on a substrate. In NIL, since a good contact state can be maintained to a flat substrate, it is easy to superpose the substrate and the template with high accuracy. On the other hand, it has been difficult to obtain good overlay accuracy for substrates having steps.

  In particular, in the outer peripheral portion of the substrate, a large level difference is likely to occur due to various steps. For this reason, even in the outer peripheral portion of the substrate, it is desirable that the pattern to be formed by the imprint process and the substrate be precisely superimposed.

Unexamined-Japanese-Patent No. 9-167753

  The problem to be solved by the present invention is to provide a pattern forming method capable of accurately superposing a substrate and a pattern to be formed.

According to an embodiment, a pattern formation method is provided. The pattern formation method includes a first application step, a first exposure step, a second exposure step, a development step, a second application step, a removal step, and a pattern formation step. There is. In the first application step, a first resist is applied onto the substrate. In the first exposure step, the first exposure light is irradiated to the convex portion of the first resist. In the second exposure step, an outer peripheral portion of the substrate in the first resist is irradiated with a second exposure light. In the developing step, the substrate is developed. In the second application step, a second resist is applied to the substrate. In the removing step, the resist portion of the outer peripheral portion of the substrate in the second resist is removed. In the pattern formation step, a pattern is formed on the upper layer side of the second resist by imprint processing. Further, in the second exposure step, after the alignment is performed on the unevenness of the outer peripheral portion of the substrate, the second exposure light is irradiated to the concave portion in the outer peripheral portion of the substrate, and The second exposure light is not irradiated to the convex portion of the outer peripheral portion.

FIG. 1 is a top view showing the structure of a substrate. FIG. 2 is a top view showing the configuration of the shot and chip areas. 3-1 is a figure (1) for demonstrating the pattern formation process procedure which concerns on embodiment. 3-2 is a figure (2) for demonstrating the pattern formation process procedure which concerns on embodiment. FIG. 4 is a diagram for explaining alignment processing in the second exposure process. FIG. 5 is a view for explaining the relationship between the light intensity distribution and the resist pattern shape. FIG. 6 is a diagram for explaining the processing procedure of the imprint process. FIG. 7 is a view for explaining the pattern shape in the case where alignment is not performed in the second exposure process.

  The pattern formation method according to the embodiment will be described in detail below with reference to the accompanying drawings. The present invention is not limited by this embodiment.

(Embodiment)
FIG. 1 is a top view showing the structure of a substrate. FIG. 1 shows a top view of a shot set on a substrate 100 such as a wafer. A rectangular area shown by squares on the substrate 100 is a shot 101. The shot 101 is an exposure unit of photolithography or a pressing unit of imprint lithography. In other words, the shot 101 is an area which can be exposed by one exposure or an area which can be imprinted by one pressing.

  At least one, and in some cases, a plurality of semiconductor devices (semiconductor chips) are disposed in the shot 101. In the outer end region (peripheral portion) of the substrate 100, there is a region (hereinafter referred to as a bevel region 62) which is a step due to the inclination. The central region of the substrate 100 is a region in which an element is formed (hereinafter, referred to as an element formation region 61). In the substrate 100, a region other than the element formation region 61 is a bevel region 62. The element formation region 61 is a circular region, and the bevel region 62 is an annular region.

  Of the shots 101, the entire region of the shot 101 is in the element formation region 61 that is disposed on the inner peripheral side of the substrate 100. On the other hand, among the shots 101 that are disposed outside the substrate 100, some of the shots 101 are out of the element formation region 61. In other words, the shots 101 include those in which the entire region is in the element formation region 61 and those in which only a partial region is in the element formation region 61.

  In the region of the shot 101 overlapping the bevel region 62, the film is removed by thinner or the like. Therefore, the bevel region 62 has a thinner film than the element formation region 61. As a result, the bevel region 62 is inclined.

  In the present embodiment, a film is formed on the substrate 100 so as to eliminate the step (concave and convex) generated in the element formation region 61. In addition, a film is formed on the substrate 100 so as to eliminate the step generated near the boundary between the bevel region 62 and the element formation region 61.

  FIG. 2 is a top view showing the configuration of the shot and chip areas. FIG. 2A shows a top view of the shot 101, and FIG. 2B shows a top view of the chip region 200X.

  As shown in FIG. 2A, the shot 101 has a plurality of chip areas. Here, the case where the shot 101 has chip areas 200A to 200F is shown. Each chip area 200A to 200F includes a device formation area 201 and a peripheral area 202.

  The chip areas 200A to 200F are rectangular areas. Each device formation area 201 is a rectangular area. Each peripheral area 202 is a rectangular annular area. Each device formation area 201 is disposed at the center of the chip area 200A to 200F. Each peripheral area 202 is disposed at the outer peripheral portion (outside of the device formation area 201) of the chip area 200A to 200F. The device formation region 201 is a region in which a semiconductor device is formed. Further, the peripheral area 202 is an area where a test pattern or the like is formed.

  The chip area 200X shown in (b) of FIG. 2 is any of the chip areas 200A to 200F. The chip area 200X has a device formation area 201 and a peripheral area 202. The peripheral area 202 is an area of the substrate surface (uppermost surface), and the device formation area 201 is an area where the substrate 100 is dug in a predetermined depth from the peripheral area 202.

  The device formation region 201 is excavated from the peripheral region 202 by a first depth (for example, 50 nm) and a second region (for example, 100 nm) from the peripheral region 202. And the second area 201B. As such, the shot 101 has various depths on the substrate 100.

  Below, the pattern formation process procedure of this embodiment is demonstrated. 3-1 is a figure (1) for demonstrating the pattern formation process procedure which concerns on embodiment. 3-2 is a figure (2) for demonstrating the pattern formation procedure which concerns on embodiment. When a pattern is formed on the substrate 100, the substrate 100 is subjected to planarization processing, and then imprint processing is performed on the substrate 100.

((A) in Figure 3-1)
Various films are formed on the substrate 100. Here, the case where the film to be processed 20 is formed on the top surface of the substrate 100 is shown. In the substrate 100, a step 10 which is a concavo-convex structure is generated. By forming the processing film 20 on the step 10, the processing film 20 also has the step 11.

  The steps 10 and 11 are steps formed in the manufacturing process of the semiconductor device. The step 10 is, for example, 100 nm. The step 11 is approximately the same height (100 nm) as the step 10 and is formed at substantially the same position as the step 11. Thus, on the surface of the film to be processed 20, the step 11 reflecting the step 10 of the substrate 100 is formed.

((B) in Figure 3-1)
After the film to be processed 20 is formed, a first resin film application step is performed. In the first resin film application step, a resist 103X is applied to the entire top surface of the substrate 100. An uneven structure reflecting the level difference 11 of the substrate 100 is formed on the surface of the resist 103X.

  The resist 103X used here has the property of being crosslinked by heating. As this resist 103X, a resist which does not dissolve out is used in the second resin film application process described later. As the resist 103X, for example, a novolac resin-based i-line resist is used. The film thickness of the resist 103X is thicker than 100 nm of the step 11. The film thickness of the resist 103X is, for example, 120 nm. After the resist 103X is applied to the entire top surface of the substrate 100, the substrate 100 is heated, for example, at 100 ° C. for 60 seconds to remove the solvent in the resist 103X.

((C) in Figure 3-1)
After this, a first exposure step is performed. In the first exposure step, the exposure light 51 is irradiated to the convex portion of the resist 103X. The exposure light 51 is irradiated onto the resist 103X through a mask (reticle) such as a photomask (not shown).

  The exposure light 51 is irradiated to the element formation region 61 on the resist 103X using, for example, an i-line stepper (exposure wavelength: about 350 nm) or the like. In this case, the exposure light 51 is applied to the substrate 100 on all the shots 101. In addition, the exposure light 51 is also irradiated in units of shots to the shots 101 which are partially out of the element formation region 61 as in the case of the inner shot 101. The exposure light 51 may be emitted in units of shots to the positions of the element formation region 61 where the shots 101 are not arranged as in the case of the inner shot 101.

  When the first exposure process is performed, alignment in exposure is performed using alignment marks (not shown) formed on the substrate 100. In this alignment, the alignment mark of the substrate 100 and the irradiation position (the position of the photomask) of the exposure light 51 are aligned.

  At the time of exposure, the depth and position of the step of the resist 103X, the exposure and development characteristics, etc. are checked beforehand, and the intensity distribution of the exposure light 51 to be irradiated is in accordance with the depth and position of the step, exposure and development characteristics, etc. It is desirable to change it. Thereby, the resist 103X can be exposed by the exposure light 51 having a light intensity distribution of a desired shape. By performing such exposure, the interface (cross-sectional shape) between the region to be exposed and the region not to be exposed can be made into a desired shape in the resist 103X. Thereby, the interface between the exposed area (resist 103B described later) and the unexposed area (resist 103A described later) has a desired shape after development.

  The photomask used herein is provided with various transmittances for each region. For example, a mask pattern having a first transmittance is formed in a first region of the photomask, and a mask pattern having a second transmittance is formed in the second region. In this photomask, the transmittance is adjusted by adjusting the slit density (line width and space width) of the line & space pattern. By using such a photomask, the convex portion of the resist 103X is selectively exposed. Note that the transmittance of the photomask may be adjusted by another method.

  The exposure light 51 may be irradiated at once to all the shots of the substrate 100. In this case, a photomask capable of batch irradiation on all the shots 101 of the substrate 100 is used. Further, the exposure light 51 may be simultaneously irradiated to the element formation region 61 of the substrate 100. In this case, a photomask capable of collectively irradiating the element formation region 61 is used.

((D) and (e) in Fig. 3-1)
In (d) of FIG. 3A, a cross-sectional view of the substrate 100 in the element formation region 61 is shown. In (e) of FIG. 3A, a cross-sectional view of the substrate 100 in the bevel region 62 is shown. The projection light of the resist 103X is exposed by irradiating the resist 103X with the exposure light 51 through the photomask. Here, the exposed region of the resist 103X is illustrated as the resist 103B. In addition, a region which is not exposed in the resist 103X is illustrated as the resist 103A.

  In the element formation region 61, in the region near the bevel region 62, the lower layer side pattern may be formed or the lower layer side pattern may not be formed. In other words, in the region where the shot 101 is not disposed in the element formation region 61, the lower layer pattern (the pattern of the film to be processed 20) is formed and the lower layer pattern is not formed. is there. Here, the substrate 100 is illustrated in the case where the pattern on the lower layer side is also formed in the element formation region 61 in which the shot 101 is not disposed. In the substrate 100 shown in (e) of FIG. 3A, the right direction of the drawing is the outer peripheral portion of the substrate 100, and the left direction of the drawing is the inner peripheral portion of the substrate 100.

  The bevel area 62 is an annular outermost area of the area on the substrate 100. The bevel area 62 is an area in which a circuit pattern or the like is not formed, and is intentionally lower in each process than the element formation area 61 which is the central area. Therefore, the bevel region 62 is inclined so as to be gradually lowered from the element formation region 61 toward the outer peripheral side of the substrate 100.

  In the element formation region 61, the boundary region with the bevel region 62 is the boundary region 14. The boundary region 14 is the outermost peripheral region of the element formation region 61 and is an annular region. The boundary region 14 has a step with the bevel region 62. Specifically, the boundary area 14 is substantially the same height as the element formation area 61 and is higher than the bevel area 62. Then, in the bevel region 62, the upper surface gradually becomes lower toward the outer peripheral side of the substrate 100. Thus, the resist 103A of the bevel region 62 has a shape along the inclined shape (inclined surface) of the bevel region 62.

  Here, since the lower-layer-side pattern is also formed in the element formation region 61 in which the shot 101 is not disposed, there is a step between the element formation region 61 and the bevel region 62. In other words, a step is generated between the boundary area 14 and the bevel area 62.

  On the other hand, when the lower layer side pattern is not formed in the element formation region 61 in which the shot 101 is not disposed, the element formation region 61 and the bevel region 62 in which the shot 101 is not disposed have substantially the same height. For this reason, the boundary between the boundary region 14 and the bevel region 62 has a simple step or no step.

((F) in Figure 3-1)
In (f) of FIG. 3A, a cross-sectional view of the substrate 100 in the bevel region 62 is shown. Of the substrate 100 shown in (f) of FIG. 3A, the right direction of the drawing is the outer peripheral portion of the substrate 100, and the left direction of the drawing is the inner peripheral portion of the substrate 100. After the first exposure step is completed, a second exposure step is performed. In the second exposure step, exposure light 52 is irradiated to bevel region 62. The exposure light 52 is, for example, irradiated to the bevel area 62 while rotating the substrate 100. In this case, for example, the area other than the bevel area 62 of the substrate 100 is shielded by a predetermined light shielding pattern, and only the bevel area 62 is irradiated with the exposure light 52.

  The exposure light 52 is, for example, light of the same wavelength as the exposure light 51 emitted by the i-line stepper. When the exposure light 52 is irradiated, the alignment is performed with respect to the unevenness of the bevel area 62 of the substrate 100, and then the exposure light 52 is irradiated to the bevel area 62. Thus, the bevel area 62 is exposed. Here, the resist of the exposed bevel area 62 of the resist 103A is illustrated as a resist 103C.

  When the second exposure step is performed, the depth and position of the step of the resist 103A in the bevel region 62, the exposure / development characteristics, etc. are checked in advance, and the intensity distribution of the exposure light 52 to be irradiated is It is desirable to change in accordance with the position, exposure and development characteristics, and the like. Thus, the bevel region 62 can be exposed by the exposure light 52 having a sharp rectangular mountain-shaped light intensity distribution. By performing such exposure, the boundary between the bevel region 62 and the boundary region 14 (the cross-sectional shape of the boundary region 14) becomes sharp after development. In other words, the interface between the bevel region 62 and the boundary region 14 becomes parallel to the irradiation direction of the exposure light 52 after development.

  On the other hand, when the bevel area 62 is exposed by the exposure light having a gentle curve-shaped mountain-shaped light intensity distribution, an exposure blur occurs at the boundary between the bevel area 62 and the boundary area 14. In this case, the boundary between the bevel region 62 and the boundary region 14 (the cross-sectional shape of the boundary region 14) becomes smooth after development. In other words, the interface between the bevel region 62 and the boundary region 14 becomes non-parallel to the irradiation direction of the exposure light after development.

  Further, it is desirable to align the exposure position in the first exposure process and the second exposure process. Here, exposure alignment processing in the second exposure process will be described. FIG. 4 is a diagram for explaining alignment processing in the second exposure process.

  In the second exposure step, as shown in FIG. 4A, the camera (imaging device) 401 measures the position of the end of the substrate 100 while the substrate rotation device 402 rotates the substrate 100. Thus, the outer position of the substrate 100 can be accurately determined.

  Next, as shown in (b) of FIG. 4, the UV irradiation mechanism 50 irradiates the substrate 100 with the exposure light 52 while the substrate rotation device 402 rotates the substrate 100. At this time, the position adjustment mechanism 55 adjusts the irradiation position by the UV irradiation mechanism 50 in accordance with the outer position of the substrate 100. The position adjustment mechanism 55 is a mechanism for adjusting the irradiation position of the exposure light 52 to the substrate 100. The position adjustment mechanism 55 has a function of adjusting the irradiation position by the UV irradiation mechanism 50 based on the outer shape reference of the substrate 100 obtained by the camera 401.

  By these processes, the resist 103A is exposed with an accurate width based on the outer shape of the substrate 100. The width of the exposure area to the bevel area 62 by the UV irradiation mechanism 50 is, for example, 3 mm. Also in the second exposure, as in the first exposure. Alignment may be performed using alignment marks (not shown) formed on the substrate 100.

((G) in Figure 3-2)
After the second exposure step is completed, a development step is performed. In (g) of FIG. 3-2 and (h) to (j) of FIG. 3-2 described later, the central portion (element formation region 61) of the substrate 100 is illustrated on the left side, and the outer periphery of the substrate 100 on the right side. The part (bevel region 62) is illustrated. In the substrate 100 shown on the right side of (g) to (j) of FIG. 3B, the right direction of the drawing is the outer peripheral portion of the substrate 100, and the left direction of the drawing is the inner peripheral portion of the substrate 100.

  In the development step, the substrate 100 is developed in one development process. The development process is performed, for example, using 2.38% TMAH (Tetra Methyl Ammonium Hydroxide) water solubility for 30 seconds.

  As a result, among the resists 103A to 103C on the substrate 100, only the exposed resist 103B and resist 103C are removed. In (g) of FIG. 3B, a region from which the resist 103B is removed is illustrated as a removal region 107, and a region from which the resist 103C is removed is illustrated as a removal region 108.

  The development processing of the substrate 100 is performed, and the resist 103B and the resist 103C are removed from the removal regions 107 and 108, so that the resist remains in the concave portion and the boundary region 14 of the substrate 100. Region 61 is flattened. In (g) of FIG. 3B, the resist pattern 104A corresponding to the resist 103A left undissolved in the developer in the element formation region 61 is illustrated. Further, in (g) of FIG. 3B, a resist pattern 104B corresponding to the resist 103A remaining without being dissolved by the developer in the boundary area 14 is illustrated. In the development step, all the resist 103A in the removal area 108 is removed, so the film 20 to be processed comes out to the surface in the bevel area 62.

  In the present embodiment, since the intensity distribution of the exposure light 51 in the first exposure step is changed according to the depth and position of the step of the resist 103X, the cross-sectional shape of the resist pattern 104A (the boundary with the removal area 107 The surface is the desired shape. This reduces the generation of dust in the subsequent processing steps.

  Further, since the intensity distribution of the exposure light 52 in the second exposure step is changed according to the depth and position of the step of the resist 103A in the bevel region 62, the cross-sectional shape of the resist pattern 104B ( Interface) is a flat surface parallel to the vertical direction. This reduces the generation of dust in the subsequent processing steps.

  Here, the resist pattern shape with respect to the intensity distribution of the exposure light 51 and 52 will be described. Since the resist pattern 104A corresponding to the exposure light 51 and the resist pattern 104B corresponding to the exposure light 52 are formed by the same phenomenon, the shape of the resist pattern 104A will be described here.

  FIG. 5 is a view for explaining the relationship between the light intensity distribution and the resist pattern shape. FIG. 5A shows an exposure process when the bevel area 62 is exposed by the exposure light 53 having the light intensity distribution 141 having a curved mountain shape instead of the exposure light 52. In such exposure, the resist pattern 104C formed instead of the resist pattern 104B becomes a footing pattern. In other words, the side surface on the bevel region 62 side of the resist pattern 104C is inclined from the irradiation direction of the exposure light 53. Thus, the boundary surface between the resist pattern 104C and the bevel region 62 (the surface where the resist pattern 104C and the line of the light intensity distribution intersect) is inclined from the vertical direction to the oblique direction.

  FIG. 5B shows the exposure process when the bevel area 62 is exposed by the exposure light 52 having the rectangular mountain-shaped light intensity distribution 140. In such exposure, the resist pattern 104B does not become a skirting pattern. In other words, the interface between the resist pattern of the resist pattern 104 B and the bevel region 62 is parallel to the irradiation direction of the exposure light 52.

((H) in Fig. 3-2)
After the development process is completed, a heating process is performed. By heating the substrate 100, the shapes of the resist patterns 104A and 104B are changed. In (h) of FIG. 3B, the shape of the resist pattern 104A in the element formation region 61 after the heating step is illustrated as a resist pattern 105A. Further, the shape of the resist pattern 104B in the bevel region 62 after the heating step is illustrated as a resist pattern 105B. When the resist patterns 104A and 104B are heated, part of the resist portion (protrusion portion) present at the time of development is reflowed to have a smooth shape.

  The first heat treatment here is performed under conditions (for example, 250 ° C., 180 seconds) at which the polymers in the resist patterns 104A and 104B start thermal crosslinking at temperatures above the glass transition temperature of the resist patterns 104A and 104B. As a result, the resist pattern 104A becomes the resist pattern 105A, the resist pattern 104B becomes the resist pattern 105B, and the surface of the substrate 100 is further planarized than before the heating step.

((I) in Fig. 3-2)
After the heating step is completed, a second resin film application step is performed. In the second resin film application step, for example, a resist 110 having the same component as the resist 103X used in the first application step is used. The resist 110 is, for example, an i-line resist of the same novolak resin system as the resist 103X used in the first application step.

  The film thickness of the resist 110 applied on the substrate 100 is, for example, 120 nm. The resist 110 is applied to the entire top surface of the substrate 100. No exposure is performed on the resist 110, and heating at 250 ° C. for 180 seconds is performed. Since the resist patterns 104A and 104B are thermally crosslinked in the heating step, even if the resist 110 is applied in the second resin film application step, the resist patterns 105A and 105B are not dissolved in the resist 110.

  In the second resin film application step, the resist 110 in the bevel region 62 of the substrate 100 is removed by thinner. As a result, in the bevel region 62 of the substrate 100, all the resist 110 is removed, and the processed film 20 comes out to the surface. In (i) of FIG. 3B, the region from which the resist 110 is removed is illustrated as a removal region 111. By applying the resist 110 in the second resin film application process, the substrate 100 is planarized more than before the application of the resist 110.

  In the present embodiment, the i-line resist is used in the first and second resin film application steps, but a coating type carbon film may be used. In the present embodiment, a photosensitive resist is used in the second resin film application step, but a non-photosensitive resist may be used. Further, in the present embodiment, the resist 110 which is a resin film is applied in the second resin film application step, but instead of the resist 110, a film other than the resin film may be formed. In addition, the flattening process of the present embodiment may be repeated multiple times.

((J) in Figure 3-2)
After the second resin film application process is completed, an imprint process such as an NIL (Nano-Imprint Lithography) process is performed. After the resist 110 is applied, a Si (silicon) -containing material 120 used for pattern transfer (processing) is formed on the substrate 100. The Si-containing material 120 is formed on the entire top surface of the substrate 100 by spin coating. Thereby, the entire top surface of the substrate 100 is covered with the Si-containing material 120. By forming the Si-containing material 120 on the substrate 100, a film having a smooth surface can be formed on a resist having small asperities. Thereafter, a resist pattern 12Y is formed on the entire top surface of the substrate 100 by an imprint apparatus (not shown).

  Here, the processing procedure of the imprint process will be described. FIG. 6 is a diagram for explaining the processing procedure of the imprint process. FIG. 6 shows a cross-sectional view of the Si-containing material 120 and the template T in the imprinting process. In FIG. 6, the layers and patterns on the lower layer side of the Si-containing material 120 are not shown. Also, illustration of a layer called an adhesive film between the Si-containing material 120 and the resist is omitted.

  As shown in FIG. 6A, a resist 12X is dropped on the upper surface of the Si-containing material 120. Thereby, each droplet of the resist 12X dropped onto the Si-containing material 120 spreads on the substrate 100. Then, as shown in (b) of FIG. 6, the template T is moved to the resist 12X side, and as shown in (c) of FIG. 6, the template T is pressed against the resist 12X.

  The template T is a mold substrate (original plate) formed using a transparent member. In the template T, a quartz substrate or the like is dug in to form a template pattern (circuit pattern or the like). When the template T is brought into contact with the resist 12X, the resist 12X flows into the template pattern of the template T by capillary action.

  After the resist 12X is filled in the template T for a preset time, exposure light (such as UV light) is irradiated. Thereby, the resist 12X is cured. Then, as shown in (d) of FIG. 6, the template T is released from the hardened resist 12X (resist pattern 12Y). Thereby, a resist pattern 12Y in which the template pattern is inverted is formed on the Si-containing material 120.

  In the imprint process, the pressing process of the template T is performed for each shot 101 of the substrate 100. In this case, when the substrate 100 has a step (concave and convex), the template T is inclined when the template T is pressed against the resist 12X. Then, when the template T is tilted, the substrate 100 and the template T can not be accurately superimposed.

  On the other hand, in the present embodiment, planarization to the substrate 100 is performed on the element formation region 61. Therefore, when the template T is pressed against the resist 12X, the template T can be prevented from being inclined. And since the template T does not incline, it becomes possible to superimpose the board | substrate 100 and the template T precisely.

  The planarization process of the substrate 100 is performed, for example, for each layer of the wafer process. Then, the semiconductor device (semiconductor integrated circuit) is manufactured by repeating the planarization process on the substrate 100 and the pattern formation process such as the imprint process.

  Specifically, after the film to be processed 20 is formed on the substrate 100, the substrate 100 is planarized. Thereafter, a resist pattern 12Y is formed on the substrate 100 by an imprinting process or the like. Then, the lower layer side (the film to be processed 20 and the like) of the resist pattern 12Y is etched using the resist pattern 12Y as a mask. Thereby, an actual pattern corresponding to the resist pattern 12Y is formed on the substrate 100. Thereafter, a new film to be processed 20 is formed on the substrate 100. When a semiconductor device is manufactured, the above-described process of forming the film to be processed 20, planarization, imprinting, etching and the like are repeated for each layer.

  Here, the pattern shape in the case where alignment is not performed in the second exposure process will be described. FIG. 7 is a view for explaining the pattern shape in the case where alignment is not performed in the second exposure process.

  When alignment is performed in the first and second exposure steps, as shown in (h) of FIG. 3B, the resist pattern 105B is located at the same position as the convex portion of the processed film 20 in the vicinity of the boundary region 14 Is formed.

  On the other hand, when alignment is not performed in the second exposure step, if the exposure position is shifted to the inner peripheral side, as shown in FIG. 7A, a resist pattern 105C is formed instead of the resist pattern 105B. Be done. The resist pattern 105C is formed in the vicinity of the boundary region 14 at a position shifted to the inner peripheral side from the convex portion of the film 20 to be processed. Thus, in the vicinity of the boundary region 14, the upper surface of the film to be processed 20 is exposed without being covered by the resist pattern 105C. In other words, the resist pattern 105 C has a step on the boundary region 14.

  In this state, when a resist is applied to the substrate 100 and the resist in the removal area 111 is removed, a resist 110A is formed as shown in FIG. 7B. The resist 110A has a step on the vicinity of the resist pattern 105C. This is caused by the presence of the region covered with the resist pattern 105C and the region not covered with the resist pattern 105C on the upper surface of the film 20 to be processed.

  If the alignment is not performed in the first exposure step, the inner peripheral side of the resist pattern 105C is formed in the vicinity of the boundary region 14 at a position deviated from the convex portion of the film 20 to be processed. . Also in this case, the resist 110A has a step on the vicinity of the resist pattern 105B.

  In addition, when alignment is not performed in the second exposure step, if the exposure position is shifted to the outer peripheral side, a resist pattern 105D is formed instead of the resist pattern 105B as shown in FIG. 7C. Ru. The resist pattern 105D is formed in the vicinity of the boundary region 14 at a position shifted from the convex portion of the film to be processed 20 to the outer peripheral side. As a result, in the bevel area 62 on the outer peripheral side of the boundary area 14, an area in which the upper surface of the film to be processed 20 is covered with the resist pattern 105 D is generated. In other words, the resist pattern 105D has a step on the bevel region 62.

  In this state, when a resist is applied to the substrate 100 and the resist in the removal region 112 is removed, a resist 110B is formed as shown in (d) of FIG. The resist 110B has a step on the vicinity of the resist pattern 105D. This is because the upper surface of the bevel region 62 has an area covered with the resist pattern 105D and an area not covered with the resist pattern 105D.

  As described above, when alignment is not performed in the first or second exposure process, the resists 110A and 110B in the vicinity of the bevel region 62 generate an unintended new level difference with the level difference on the substrate 100. . If such a step is generated, even if the substrate 100 is planarized, the alignment accuracy in the bevel region 62 is deteriorated in the imprint process.

  On the other hand, in the present embodiment, since the alignment is performed in the first and second exposure steps, the level difference in the bevel region 62 is controlled to a desired shape. Therefore, it is possible to improve the superposition accuracy at the time of imprinting, and to prevent the occurrence of defects caused by the unevenness of the substrate 100.

  As described above, in the present embodiment, the first exposure process and the second exposure process are performed on the resist 103X on the substrate 100. In the first exposure step, the convex portion of the element formation region 61 is irradiated with the exposure light 51. Further, in the second exposure process, the bevel region 62 of the substrate 100 is irradiated with the exposure light 52. Thereafter, the substrate 100 is developed, and then the resist 110 is applied on the substrate 100. Then, the resist 110 in the bevel region 62 of the substrate 100 is removed. Thereafter, a pattern is formed on the upper layer side of the resist 110 by imprint processing.

  As described above, since the convex portion and the outer peripheral region of the element formation region 61 are exposed by the two exposure processes, the level difference of the substrate 100 is alleviated. Therefore, the substrate 100 and the resist pattern 12Y formed by the imprint process can be accurately superimposed.

  While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

  10, 11: step, 12X: resist, 12Y: resist pattern, 14: boundary area, 20: film to be processed, 51, 52: exposure light, 61: element formation area, 62: bevel area, 100: substrate, 101: Shot, 103A to 103C, 103X: resist, 104A, 104B, 105A, 105B: resist pattern, 110: resist, 120: Si-containing material, T: template.

Claims (5)

Applying a first resist onto the substrate;
A first exposure step of irradiating the first exposure light to the convex portion of the first resist;
A second exposure step of irradiating a second exposure light to an outer peripheral portion of the substrate in the first resist;
Developing the substrate;
Applying a second resist to the substrate;
Removing the resist portion of the outer peripheral portion of the substrate in the second resist;
Forming a pattern on the upper layer side of the second resist by imprinting;
Only including,
In the second exposure step, after the alignment is performed with respect to the unevenness of the outer peripheral portion of the substrate, the second exposure light is irradiated to the concave portion of the outer peripheral portion of the substrate, The second exposure light is not irradiated to the convex portion of
A pattern forming method characterized by In the first exposure step, the exposure amount of the first exposure light is adjusted based on the height and position of the step of the first resist.
The pattern formation method according to claim 1 , In the second exposure step, the exposure amount of the second exposure light is adjusted based on the height and position of the step on the outer peripheral portion of the substrate.
The pattern formation method according to claim 1 or 2 , characterized in that And heating the substrate after development to thermally crosslink the first resist.
The thermally crosslinked first resist is insoluble in the second resist.
The pattern formation method as described in any one of the Claims 1-3 characterized by the above-mentioned. In the second exposure step, the outer peripheral portion of the substrate is irradiated with the second exposure light while rotating the substrate.
The pattern formation method as described in any one of the Claims 1-4 characterized by the above-mentioned.

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