JP2007223206A - Method of forming pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a pattern having a uniform height from the surface of a board, even if the flat characteristic of the gap between the board and the mold varies. <P>SOLUTION: The method of patterning comprises the first step to form a first layer 2 and a second layer 3 on the board 1 in this order using an organic material or an inorganic material and to coat a liquid resin 4 on the second layer, the second step to contact a mold 5 corresponding to the pattern with the resin and to cure the resin and the third step to form the pattern by etching the cured resin, the first layer and the second layer. In the third step, a first etching is made to the extent that the resin remains on the part of the second layer corresponding to the pattern and the rest part of the first layer is exposed and a second etching is made to the remaining resin and the exposed first layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for forming a pattern on a substrate (generally referred to as a nanoimprint technique) by bringing a pattern formed on a mold into contact with a resin material disposed on the substrate and curing it.

  Nanoimprint technology is used to form fine patterns used in various devices and optical elements such as semiconductor chips such as IC and LSI, display elements such as liquid crystal panels, detection elements such as magnetic heads, and imaging elements such as CCD sensors ( Non-patent document 1).

  The pattern transfer method using nanoimprinting includes a thermal cycle method in which a polymer used as a resist is heated to a glass transition temperature or higher, and then the polymer is cured and released in order to improve the fluidity of the resist with respect to the mold. Further, there is a photocuring method or a UV curing method in which an ultraviolet curable resin (UV curable resin) is used as a resist, and is exposed to light and cured in a state where a transparent mold is in contact, and then released.

  The UV curing method is disclosed in Patent Document 1, for example. As disclosed in Patent Document 1, a method using only a UV curable resin in a single layer is referred to as a “single layer process” in this specification.

  The nanoimprint process of the photocuring method is shown in FIG.

  In the first step (a), a mold (also referred to as a template) 26 made of a material that transmits ultraviolet rays (for example, quartz) is pressed against a UV curable resin 25 applied on a substrate 24 such as a wafer. The UV curable resin 25 flows along a pattern formed in the mold.

  In the second step (b), ultraviolet rays 27 are irradiated in a state where the mold 26 is pressed against the substrate (UV curable resin) 24. Thereby, UV hardening resin hardens | cures in the shape along the pattern of a mold.

  In the third step (c), the mold 26 is pulled away from the substrate 24. A resist pattern 25 ′ is formed by leaving the UV curable resin in a pattern shape on the substrate.

  The resist pattern 25 'thus formed is equivalent to a resist pattern transferred by a conventional light exposure apparatus. This is referred to as “etching barrier” in the following description. The subsequent process is the same as the conventional LSI manufacturing process.

  Further, Patent Document 2 proposes a process for forming a base layer on a substrate before placing a resin for the purpose of filling the unevenness of the substrate and flattening the substrate. In this specification, the method for forming the base layer is referred to as “two-layer process”.

Furthermore, Non-Patent Document 2 proposes a process for forming a nanoimprint inversion pattern. Such a process is referred to herein as an “inversion process”.
JP 2000-194142 A USP 6,344,960B1 SY Chou, et.al., Science, vol.272, p.85-87, 5 April 1996 MICRO Magazine. JAN / FEB 2005 "Reverse Tone Bi-Layer Etch in UV Nanoimprint Lithography"

  When a fine pattern is actually formed on a semiconductor substrate using nanoimprint technology, the height of the etching barrier varies within the substrate due to factors such as substrate flatness, mold flatness, mechanical accuracy, and resin shrinkage. . Due to this, a phenomenon such as so-called RIE-lag occurs, and the finished dimensions of the device vary, so that sufficient device performance cannot be obtained. In addition, the yield decreases due to deterioration of dimensional accuracy.

  The manner in which the aspect ratio varies in the single layer process will be described with reference to FIG. The actual substrate 24 is not completely flat as shown in FIG. 7A, but has a finite undulation. It is known that the amount of waviness further increases after the CMP (Chemical Mechanical Polishing) process as well as the original waviness of the substrate 24.

  The photocurable resin 25 is applied to the substrate 24 (FIG. 7B). Next, the mold 26 is pressed against the resin (FIG. 7C), and light 27 is irradiated while maintaining the state (FIG. 7D). Then, by releasing the mold, a photocurable resin pattern 25 'is formed (FIG. 7 (e)).

  At this time, the distance between the lower surface of the mold 26 and the substrate (hereinafter referred to as gap flatness in this specification) is not uniform due to the undulation of the substrate. Although not shown in the figure, since the mold waviness actually exists, the gap flatness is further deteriorated.

  In this state, when the remaining film of the resin pattern 25 ′ is removed by dry etching or the like, the etching barrier 29 is completed as shown in FIG. At this time, since the gap flatness varies, the height of the etching barrier 29 from the substrate surface varies. If the gap flatness is larger than the mold height, the resin pattern partially disappears after the remaining film is removed, as shown in FIG. Therefore, there is a restriction that the flatness of the substrate must be smaller than the height of the pattern in the mold.

  In this case, it suffices if the pattern height of the mold can be increased, but in reality, if the pattern height is too high, the releasability deteriorates and the resin pattern is damaged. For example, as shown in FIG. 7C, when H17 / W5, which is the ratio of the pattern width W5 of the mold 26 to the pattern height H17, is 2.5 or more, defects in the resin pattern occur frequently due to mold release.

  Further, when the gap flatness is poor, the time until the substrate surface is exposed during etching differs depending on the location. For this reason, as a result, the overetch time of the portion having a thin residual film thickness becomes long, so that there is a disadvantage that CD (critical dimension) variation of the etching barrier becomes large.

  Further, how the aspect ratio varies in the two-layer process will be described with reference to FIG. First, the base layer 31 is formed on the substrate 30 shown in FIG. 8A (FIG. 8B). For the formation of the underlayer 31, methods such as spin coating, vapor deposition, and CVD are used. In any method, the underlayer 31 is formed in a shape that follows the undulation of the substrate 30.

  Next, a photo-curing resin 32 is applied on the base layer 31 (FIG. 8C). Next, the mold 33 is pressed against the resin 32, and light 34 is irradiated while maintaining the state (FIG. 8D). After the mold release, a light curable resin pattern 32 ′ is formed (FIG. 8E). At this time, the underlayer 31 is formed following the undulation of the substrate 30, whereas the gap flatness is not uniform due to the undulation of the substrate 30. Although not shown in the figure, since the mold 33 actually has undulations, the gap flatness is further deteriorated.

  In this state, when the remaining film of the resin pattern 32 'is removed by dry etching or the like, the result is as shown in FIG. At this time, since the gap flatness varies, the height of the remaining portion of the resin pattern 32 ′ varies. When the gap flatness is larger than the pattern height of the mold 33, the resin pattern 32 'disappears partially after the remaining film is removed, as in the single layer process.

  Next, the underlying layer 31 is etched using the remaining portion of the resin pattern 32 'as a mask. When the etching rate ratio between the resin and the underlayer is increased, the etching barrier 37 as shown in FIG. 8G is completed even if the remaining portion of the resin pattern is thin. Therefore, the height of the etching barrier 37 can be increased as compared with the single layer process.

  However, the height of the etching barrier varies due to variations in gap flatness.

  Next, how the aspect ratio varies in the inversion process will be described with reference to FIG. First, a photo-curing resin 39 is applied on the substrate 38 shown in FIG. 9A (FIG. 9B). Next, the mold 40 is pressed against the resin 39 (FIG. 9C), and the light 41 is irradiated while maintaining the state (FIG. 9D). And after mold release, photocuring resin pattern 39 'is made (FIG.9 (e)). At this time, the gap flatness is not uniform due to the undulation of the substrate 38. Although not shown, the gap flatness is further deteriorated due to the undulation of the mold 40 in practice.

  Next, the inversion layer 43 is formed on the resin pattern 39 ′ (FIG. 9F). Thereafter, the reverse layer 43 is etched back until the upper portion of the resin pattern 39 'is exposed ((g) in FIG. 9).

  Further, when the resin pattern 39 'is etched using the remaining part of the inversion layer 43 as a mask, the etching barrier 46 is completed as shown in FIG.

  In the case of this inversion process, there is no restriction that the flatness of the substrate must be smaller than the pattern height of the mold. However, the height of the etching barrier varies due to variations in gap flatness, as in the single-layer process and the two-layer process.

  The present invention provides a pattern forming method capable of forming a pattern (etching barrier) having a uniform height from the substrate surface even when there is variation in gap flatness between the substrate and the mold. One of the purposes.

  The pattern forming method as one aspect of the present invention includes a first step of forming a first layer and a second layer in this order on a substrate, and applying a liquid resin on the second layer; A second step of bringing the corresponding mold into contact with the resin and curing the resin, and a third step of etching the cured resin and the first and second layers to form a pattern. Then, in the third step, the first etching is performed until the resin remains on the second layer of the portion corresponding to the pattern and the first layer of the other portion is exposed, and the remaining resin The second etching is performed on the exposed first layer.

  The pattern forming method as another aspect of the present invention includes a first step of forming a first layer and a second layer in this order on a substrate, and applying a liquid resin on the second layer. A second step of bringing the mold corresponding to the pattern into contact with the resin and curing the resin; a third step of forming a third layer on the cured resin; and etching back the third layer; And a fourth step of etching the first to third layers to form a pattern on the substrate. Then, in the fourth step, the first etching is performed until the third layer remains on the portion of the resin corresponding to the pattern and the second layer is exposed to the other portion, thereby corresponding to the pattern. The second etching is performed until the resin remains on the second layer of the part to be exposed and the first layer of the other part is exposed, and the remaining resin and the exposed first layer are further removed. A third etching is performed on the substrate.

  In addition, the board | substrate manufacturing system which manufactures the board | substrate which has a pattern using the said pattern formation method also comprises the other side surface of this invention. In addition, a method of manufacturing a substrate having a pattern using the pattern forming method constitutes another aspect of the present invention. Furthermore, a device manufacturing method in which a pattern is formed on a substrate using the pattern forming method, the substrate is etched, and a device is manufactured using the etched substrate constitutes another aspect of the present invention.

  According to the present invention, even if there is variation in the flatness of the gap between the substrate and the mold, the resin and the first layer are etched using the second layer following the waviness of the substrate as a mask. A uniform pattern (etching barrier) can be formed.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the procedure of a pattern forming method that is Embodiment 1 of the present invention. FIG. 2 shows a flowchart of the pattern forming method.

  First, the outline of the pattern forming method of the present embodiment will be described with reference to FIG. In step (abbreviated as “S” in the figure) 1, a first layer is formed on a substrate such as a semiconductor wafer or an optical element by using a film forming apparatus 100 such as a spin coater, a CVD apparatus, or a PVD apparatus. The base layer and the intermediate layer as the second layer are applied or formed in this order (from the substrate side, in the order of the base layer as the first layer and the intermediate layer as the second layer). The material of these underlayer and intermediate layer will be described later.

  Next, in step 2, the substrate is set in the nanoimprint apparatus 200. In step 3, a UV curable resin is applied onto the substrate (intermediate layer).

  Next, in step 4, a template which is a transparent mold is pressed against the UV curable resin. A pattern having a shape corresponding to the etching barrier is formed on the tape rate.

  In step 5, the UV curable resin is irradiated with UV light through the template. After the UV curable resin is cured, in step 6, the template is peeled from the UV curable resin. Thereby, a UV curable resin having a pattern shape corresponding to the etching barrier is formed.

  In step 7, the substrate on which the resin pattern is formed is set in the first etching apparatus 300. In step 8, the substrate is subjected to first etching described later.

  Next, in step 9, the substrate after the first etching is set in the second etching apparatus 400. In step 10, second etching described later is performed on the substrate. Thus, a substrate on which a desired etching barrier is formed is completed.

  The film forming apparatus 100, the nanoimprint apparatus 200, and the first and second etching apparatuses 300 and 400 constitute a substrate manufacturing system. The first and second etching apparatuses 300 and 400 may be different apparatuses or the same apparatus.

  Hereinafter, specific processing in each step described above with reference to FIG. 1 will be described with reference to materials and numerical examples.

  First, the substrate 1 shown in FIG. 1A is prepared, and the base layer 2 and the intermediate layer 3 are formed on the substrate 1 in this order (FIG. 1B, step 1). As the material of the underlayer 2, in this embodiment, a BARK material for KrF used in normal photolithography is used. As the material of the intermediate layer 3, HSQ (Hydrogen Silsequioxane) is used.

  These layers are preferably formed by spin coating as described above. When applied by spin coating, a film (layer) that follows the undulation of the substrate 1 is formed as shown in FIG. The underlayer 2 and the intermediate layer 3 may be formed by a CVD method, a PVD method, or the like. Furthermore, as a material for the base layer 2 and the intermediate layer 3, in addition to organic substances, an inorganic film such as a SiN film or a SiON film may be used. In this embodiment, the thickness H2 of the underlayer 2 is 64 nm, and the thickness H4 of the intermediate layer 3 is 20 nm.

  Next, a liquid UV curable resin 4 is applied on the intermediate layer 3 (step 3). As the UV curable resin 4, for example, a material in which a group that improves dry etch resistance such as an adamantyl group is included in an acrylic resin is used.

  Then, the transparent template 5 is pressed against the resin 4 (FIG. 1 (c), step 4), and the UV light 6 is irradiated while maintaining the state (FIG. 1 (d), step 5). Thereby, the resin 4 is cured. The template 5 has a concavo-convex shape (mold pattern) corresponding to a pattern to be formed on a semiconductor device (such as a large-scale integrated circuit or MEMS) or an optical element (such as a diffractive optical element).

  In this embodiment, the depth H1 of the concave portion of the template 5 is 70 nm, and the width W1 of the concave portion and the width W2 of the convex portion are both 32 nm.

  Next, the template 5 is peeled from the resin 4 (FIG. 1 (e), step 6). As a result, a cured resin pattern layer (hereinafter referred to as an imprint layer) 4 ′ is formed on the intermediate layer 3. After the template 5 is peeled off, the UV curable resin shrinks. The pattern height H3 of the imprint layer 4 ′ after shrinking is 64 nm.

At this time, as described above, the gap flatness, which is the distance between the lower end surface of the template 5 and the substrate 1, is not uniform due to the undulation of the substrate 1. Further, although not shown, the template 5 has a twist. For this reason, the gap flatness is further deteriorated. The gap flatness is a residual film corresponding to the maximum and minimum distances between the upper surface of the intermediate layer 3 and the bottom surface of the concave portion of the imprint layer 4 ′ (the lower end surface of the convex portion of the template 5) shown in FIG. Using the maximum thickness A and the minimum residual film thickness B,
AB
It is represented by The gap flatness in this example is 32 nm.

Next, as the first etching, the imprint layer 4 ′, the intermediate layer 3 and the underlayer 2 are sequentially etched (step 8). Then, when the underlying layer 2 other than the portion corresponding to the etching barrier is completely exposed, the etching is stopped (FIG. 1F). As the etching conditions at this time, for example, in a dry etching method using CHF ₃ gas, a parallel plate RIE (Reactive Ion Etching) apparatus is used, the RF power is 150 W, and the etching pressure is 3 Pa. Set.

  R1 / R2 which is the ratio of the etching rate R1 of the imprint layer 4 ′ and the etching rate R2 of the intermediate layer 3 in this dry etching is 3. R1 / R3, which is the ratio of the etching rate R1 of the imprint layer 4 ′ and the etching rate R3 of the underlayer, is 1.

  The minimum thickness H6 and the maximum thickness H7 of the remaining portion of the imprint layer 4 ′ when the first etching is finished are 32 nm and 64 nm, respectively. Further, the remaining film thickness H5 of the base layer 3 at the position where the gap distance is minimum is 59 nm.

  In this etching, the material and the etching conditions may be combined with the etching rate R3 of the base layer 2 that is slower than the etching rate R1 of the imprint layer 4 ′. Thereby, the imprint layer 4 ′ can be completely removed when the etching barrier is completed.

  Next, underlayer etching is performed as second etching (step 10). As an etching condition at this time, for example, when dry etching is performed with oxygen gas, the remaining portion of the imprint layer 4 'is also etched at the same time. The dry etching is performed using, for example, a parallel plate type RIE with an oxygen gas of 100 sccm, an RF power of 150 W, and an etching pressure of 3 Pa.

  R4 / R5, which is the ratio of the etching rate R4 of the imprint layer 4 ′ and the etching rate R5 of the intermediate layer 3 in this underlayer etching, is 100. R4 / R6, which is the ratio of the etching rate R4 of the imprint layer 4 'and the etching rate R6 of the underlayer 3, is 1.

  Thereby, the substrate 1 on which the etching barrier 9 as shown in FIG. 1G is finally formed is completed. Here, as shown in the figure, a pattern having a uniform height is formed regardless of the waviness (gap flatness) of the etching barrier 9, the substrate 1 and the template 5. In this embodiment, the height H8 of the etching barrier is 84 nm.

  In the description of FIG. 2, the etching apparatus that performs the first etching and the second etching is described as being different from each other. However, these may be performed by the same etching apparatus.

  Furthermore, in this base layer etching, it is desirable to combine the etching conditions with a material that makes the etching rate R6 of the base layer 2 slower than the etching rate R4 of the imprint layer 4 ′. Thereby, the imprint layer 4 'can be completely removed when the etch barrier is completed.

  However, the present invention is not particularly limited to the materials, etching conditions, and film forming conditions of each layer described above.

  Further, regarding the maximum remaining film thickness indicated by A in FIG. 1 (e), the condition that the height of the etching barrier becomes uniform is that the remaining portion (maximum film) of the imprint layer 4 'is etched while the underlayer 3 is etched. Thickness H7) is completely etched.

H7 is transferred when the depth H1 of the concave portion of the template 5 is transferred and shrinks at the time of photocuring, and further decreases while the etching of the intermediate layer 3 is completed. H3 and H7 are equal. From this,
H1 <(H3 / H1) × (R1 ′ / R2 ′) × H2
It is a condition to satisfy.

  However, H1 is the mold pattern height of the template 5, H2 is the thickness of the underlayer 2, R1 ′ is the etching rate of the imprint layer 4 ′ during the underlayer etching, and R2 ′ is the lower during the underlayer etching 2. This is the etching rate of the formation 2. H3 is the height of the resin pattern formed on the imprint layer 4 '.

  FIG. 3 shows the procedure of a pattern forming method that is Embodiment 2 of the present invention. FIG. 4 shows a flowchart of the pattern forming method.

  First, the outline of the pattern formation method of a present Example is demonstrated using FIG. In step 51, an intermediate layer as a first layer and an intermediate layer as a second layer are formed on a substrate such as a semiconductor wafer or an optical element using a film forming apparatus 100 such as a spin coater, a CVD device, or a PVD device. The layers are formed in this order. The material of these underlayer and intermediate layer will be described later.

  Next, in step 52, the substrate is set in the nanoimprint apparatus 200. In step 53, a UV curable resin is applied on the substrate (intermediate layer).

  Next, in step 54, a template which is a transparent mold is pressed against the UV curable resin. A pattern having a shape corresponding to the etching barrier is formed on the tape rate.

  In step 55, the UV curable resin is irradiated with UV light through the template. After the UV curable resin is cured, in step 56, the template is peeled from the UV curable resin. Thereby, a UV curable resin having a pattern shape corresponding to the etching barrier is formed.

  Next, in step 57, in order to form an inversion layer on the UV curable resin, the substrate is set in a film forming apparatus (inversion layer forming apparatus) 500 such as a spin coat apparatus, a CVD apparatus, or a PVD apparatus. The film forming apparatus 500 may be the same as the film forming apparatus 100 used in step 51. In step 58, an inversion layer is formed. The material of the inversion layer will be described later.

  Next, in step 59, the substrate on which the inversion layer is formed is set in the inversion layer etching apparatus 600, and in step 60, the inversion layer is etched back (planarized).

  Next, in step 61, the substrate on which the inversion layer is etched back is set in the first etching apparatus 700. In step 62, a first etching described later is performed on the substrate.

  Next, in step 63, the substrate after the first etching is set in the second etching apparatus 800. In step 64, a second etching described later is performed on the substrate.

  In step 65, the substrate after the second etching is set in the third etching apparatus 900. In step 66, a third etching described later is performed on the substrate. Thus, a substrate on which a desired etching barrier is formed is completed.

  The film forming apparatus 100, nanoimprint apparatus 200, inversion layer forming apparatus 500, inversion layer, first, second, and third etching apparatuses 500 to 900 constitute a substrate manufacturing system. The inversion layer, first, second, and third etching apparatuses 500 to 900 may be different apparatuses, or all or a part thereof may be the same.

Hereinafter, specific processing in each step described above with reference to FIG. 3 will be described with reference to materials and numerical examples.
First, the substrate 10 shown in FIG. 3A is prepared, and the base layer 11 and the intermediate layer 12 are formed in this order on the substrate 10 (FIG. 3B, step 51). As the material for the underlayer 11, in this embodiment, a BARK material for KrF used in normal photolithography is used. Further, as the material of the intermediate layer 12, a Si-containing material such as SOG (Spin On Glass) or HSQ (Hydrogen Silsequioxane) is used.

  These layers are preferably formed by spin coating as described above. When applied by spin coating, a film (layer) that follows the undulation of the substrate 10 is formed as shown in FIG. The underlayer 11 and the intermediate layer 12 may be formed by a CVD method, a PVD method, or the like. Furthermore, as a material for the base layer 11 and the intermediate layer 12, an inorganic film such as a SiN film or a SiON film may be used in addition to an organic substance. In this embodiment, the thickness H9 of the underlayer 11 is 150 nm, and the thickness H10 of the intermediate layer 12 is 20 nm.

  Next, a liquid UV curable resin 13 is applied on the intermediate layer 12 (step 53). As the UV curable resin 4, for example, a material in which a group that improves dry etch resistance such as an adamantyl group is included in an acrylic resin is used.

  Then, the transparent template 14 is pressed against the resin 13 (FIG. 3C, step 54), and the UV light 15 is irradiated while maintaining the state (FIG. 3D, step 55). Thereby, the resin 13 is cured. Similar to the first embodiment, the template 14 has a concavo-convex shape (mold pattern) corresponding to the pattern to be formed on the substrate.

  In this embodiment, the depth H11 of the concave portion of the template 14 is 70 nm, and the width W4 of the concave portion and the width W3 of the convex portion are both 32 nm. The maximum value C ′ of the remaining film thickness after pressing the template is 200 nm, and the minimum value D ′ is 100 nm.

  Next, the template 14 is peeled from the resin 13 (FIG. 3 (e), step 56). Thereby, a cured resin pattern layer (hereinafter referred to as an imprint layer) 13 ′ is formed on the intermediate layer 12. After the template 14 is peeled off, the UV curable resin shrinks. The pattern height H12 of the imprint layer 13 ′ after shrinking is 64 nm.

At this time, as described above, the gap flatness, which is the distance between the lower end surface of the template 14 and the substrate 10, is not uniform due to the undulation of the substrate 10. Although not shown, the template 14 has a twist. For this reason, the gap flatness is further deteriorated. The gap flatness is a residual film corresponding to the maximum and minimum distance between the upper surface of the intermediate layer 12 and the bottom surface of the concave portion of the imprint layer 13 ′ (the lower end surface of the convex portion of the template 14) shown in FIG. Using the maximum thickness C and the minimum residual film thickness D,
CD
It is represented by The gap flatness in this example is 32 nm.

  Next, the inversion layer 16 as a third layer is formed on the imprint layer 13 '(FIG. 3 (f), step 58). For the material of the inversion layer, for example, a Si-containing material such as SOG or HSQ is used. The thickness H13 of the inversion layer 16 is 200 nm.

  Then, the inversion layer 16 is etched back until the upper portion 13a of the imprint layer 13 ′ is exposed (FIG. 3G, step 60). The remaining film thickness H14 of the inversion layer 16 after the etch back is 22 nm.

Next, as a first etching, the imprint layer 13 ′ is etched using the remaining film portion of the inversion layer 16 as a mask. Then, the etching is stopped when the intermediate layer 12 in a portion other than the portion corresponding to the etching barrier is completely exposed (FIG. 3 (h), step 62). As the etching conditions at this time, for example, in a dry etching method using CHF ₃ gas, parallel plate RIE is used, oxygen gas is set to 100 sccm, RF power is set to 150 W, and etching pressure is set to 3 Pa.

  R7 / R8, which is the ratio of the etching rate R7 of the imprint layer 13 ′ and the etching rate R8 of the inversion layer 16 during this dry etching, is 100. R7 / R9, which is the ratio of the etching rate R7 of the imprint layer 13 'and the etching rate R9 of the intermediate layer 12, is 100.

  Next, as a second etching, the intermediate layer 12 is etched using the remaining film portion of the imprint layer 13 ′ as a mask. At this time, etching is performed until the underlying layer 11 in a portion other than the portion corresponding to the etching barrier is completely exposed (FIG. 3I, step 64). Subsequently, the portion of the underlayer 11 from which the intermediate layer 12 has been removed is etched, and the etching is stopped when the minimum remaining film thickness portion 12a shown in FIG. 3 (j)).

  In this second etching, an etching condition is selected in which the remaining film portion of the imprint layer 13 ′ is etched simultaneously with the base layer 11. Furthermore, it is desirable to select a combination of etching conditions and materials that make the etching rate of the imprint layer 13 ′ faster than the etching rate of the underlayer 11.

  For example, when an acrylic UV curable resin is used as the material of the imprint layer 13 ′, HSQ is used as the material of the intermediate layer 12, and a BARK material for KrF is used as the material of the underlayer 11, the following etching conditions are used. preferable.

As an etching method, a dry etching method using CHF ₃ gas is used. R10 / R11, which is the ratio of the etching rate R10 of the imprint layer 13 ′ and the etching rate R11 of the underlayer 11 during the dry etching, is 2.

  As a result of the second etching, the film thickness H15 of the portion 13b which is the maximum remaining film thickness portion in the imprint layer 13 ′ becomes 100 nm, and the film thickness H16 of the base layer 11 also becomes 100 nm.

  Next, as the third etching, the remaining film portion of the base layer 11 and the remaining film portion 13b of the imprint layer 13 ′ are simultaneously etched (step 66). Thereby, the remaining film part 13b of the imprint layer 13 ′ is completely removed, and the intermediate layer 12 corresponding to the etching barrier is exposed. Thereafter, the underlying layer 11 is continuously etched using the intermediate layer 12 as a mask, and the etching is stopped when the surface of the substrate 10 other than the portion corresponding to the etching barrier is exposed (FIG. 3 (k)).

  This third etching uses a dry etching method using oxygen gas. R12 / R13, which is the ratio of the etching rate R12 of the imprint layer 13 ′ and the etching rate R13 of the underlayer 11 during this dry etching, is 1. R13 / R14, which is the ratio of the etching rate R13 of the underlayer 11 and the etching rate R14 of the intermediate layer 12, is 100.

  As described above, when the third etching was started, the film thickness H15 was 100 nm, and the film thickness H16 was 100 nm. Therefore, the etching of the portion 13b which is the maximum remaining film thickness portion of the imprint layer 13 'and the underlying layer 11 after the second etching is simultaneously completed. As described above, the etching barrier 19 is completed.

  According to the process of the present embodiment, the height of the etching barrier 19 is determined by the intermediate layer 12 functioning as a mask. Therefore, the height of the finally formed etching barrier 19 from the substrate 10 becomes uniform.

  In addition, although each said Example demonstrated the case where the nanoimprint by UV curing method was used, this invention is applicable also when using nanoimprint other than UV curing method.

  Next, a semiconductor device manufacturing process using the pattern forming method of each embodiment described above will be described with reference to the flowchart of FIG. The pattern forming method of the present invention can be used not only for manufacturing semiconductor devices but also for manufacturing various devices such as optical elements.

  In step 101 (circuit design), a semiconductor device circuit is designed. In step 102 (mold creation), a template as a necessary number of molds is created based on the circuit designed in step 101. On the other hand, in step 103 (wafer manufacture), a wafer is manufactured using a material such as silicon.

  The next step 104 (wafer process) is called a pre-process, and an etching barrier corresponding to an actual circuit is created on the wafer by using the template and the wafer and using the pattern forming method of each of the above embodiments. Further, etching or other processing for actual circuit formation is performed on the wafer having an etching barrier. In etching for circuit formation, the height of the etching barrier formed on the wafer from the wafer surface is uniform as described above, so that the etching depth can be easily controlled. Therefore, the finished dimensions of the device are uniform, and sufficient device performance can be obtained. Further, it is possible to avoid a decrease in yield due to deterioration in dimensional accuracy.

  The next step 105 (assembly) is called a post-process, and is a process for converting the wafer processed in step 104 into a semiconductor chip. This post-process includes assembly processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation).

  In the next step 106 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 105 are performed. A semiconductor device is completed through these processes, and is shipped in Step 107.

Schematic explaining the pattern formation method which is Example 1 of this invention. 3 is a flowchart showing a process of the pattern forming method according to the first embodiment. Schematic explaining the pattern formation method which is Example 2 of this invention. 9 is a flowchart showing a process of a pattern forming method according to a second embodiment. The flowchart which shows the manufacturing process of the semiconductor device using the pattern formation method of each Example. Schematic explaining the conventional nanoimprint method. Schematic explaining the conventional pattern formation method. Schematic explaining the conventional pattern formation method. Schematic explaining the conventional pattern formation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 Substrate 2,11 Underlayer 3,12 Intermediate layer 4,13 UV curable resin 5,14 Template 6,15 UV light 4 ', 13' Imprint layer 9,19 Etching barrier 16 Inversion layer

Claims (10)

A method for forming a pattern on a substrate, comprising:
Forming a first layer and a second layer in this order on the substrate, and applying a liquid resin on the second layer;
A second step of bringing a mold corresponding to the pattern into contact with the resin and curing the resin;
Etching the cured resin, the first and second layers to form the pattern, and a third step,
In the third step,
Performing the first etching until the resin remains on the second layer of the portion corresponding to the pattern and the first layer of the other portion is exposed,
A pattern forming method comprising performing a second etching on the remaining resin and the exposed first layer. In the first and second etching, the etching rate of the second layer is lower than the etching rate of the resin and the first layer,
The etching rate ratio of the second layer to the resin and the first layer in the second etching is lower than the etching rate ratio in the first etching. Pattern forming method.   The pattern forming method according to claim 2, wherein an etching rate of the resin in the first and second etchings is higher than an etching rate of the first layer. The pattern forming method according to claim 1, wherein the following condition is satisfied.
H1 <(H3 / H1) × (R1 ′ / R2 ′) × H2
However, H1 is the height of the mold pattern formed in the mold, H2 is the thickness of the first layer, R1 is the etching rate of the resin in the second etching, and R2 is the height in the second etching. The etching rate H3 of the first layer is the height of the resin pattern formed on the resin by the mold pattern. A method for forming a pattern on a substrate, comprising:
Forming a first layer and a second layer in this order on the substrate, and applying a liquid resin on the second layer;
A second step of bringing a mold corresponding to the pattern into contact with the resin and curing the resin;
Forming a third layer on the cured resin and etching back the third layer;
Etching the resin and the first to third layers to form the pattern on the substrate; and
In the fourth step,
The first etching is performed until the inversion layer remains on the resin corresponding to the pattern and the second layer is exposed to the other part,
Performing the second etching until the resin remains on the second layer of the portion corresponding to the pattern and the first layer of the other portion is exposed,
A pattern forming method comprising performing a third etching on the remaining resin and the exposed first layer. In the first etching, the etching rate of the second layer and the third layer is lower than the etching rate of the resin,
In the second etching, the etching rate of the first layer is lower than the etching rate of the resin,
In the third etching, the etching rate of the second layer is lower than the etching rate of the resin and the first layer,
The etching rate ratio of the second layer to the resin and the first layer in the third etching is lower than the etching rate ratio in the second etching. Pattern forming method.   The pattern forming method according to claim 6, wherein an etching rate of the resin in the second and third etchings is higher than an etching rate of the first layer.   A substrate manufacturing system for manufacturing a substrate having a pattern using the pattern forming method according to claim 1.   A substrate manufacturing method comprising manufacturing a substrate having a pattern using the pattern forming method according to claim 1. Using the pattern forming method according to claim 1 to form a pattern on a substrate;
Etching the substrate;
And a device manufacturing method using the etched substrate.