JP2012074566A - Pattern formation method and pattern formation body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern formation method and a pattern formation body, suitable for forming a three-dimensionally structured fine patterns having a plurality of steps.SOLUTION: In the pattern formation method and the pattern formation body having the three-dimensionally structured fine patterns with the plurality of steps, the pattern formation method includes: forming a hard mask layer 12 of a first layer, an etch stopper layer 13 and a hard mask layer 22 of a second layer; patterning the hard mask layers and the etch stopper layer; and performing anisotropic etching on the substrate 11, using the hard mask layers as etching masks.

Description

  The present invention relates to a method for forming a fine three-dimensional structure pattern, and a pattern forming body manufactured using the pattern forming method.

Structures in which a specific fine three-dimensional structure pattern is formed on a substrate are widely used. Examples of the structure in which a fine three-dimensional structure pattern is formed include a semiconductor device, an optical element, a wiring circuit, a recording device, a medical inspection chip, a display panel, a microchannel, and the like.
In recent years, there has been an increasing demand for finer patterns and structures with more stages. For example, in the semiconductor field, a dual damascene structure in which a specific fine three-dimensional structure pattern is formed has been proposed.

  For example, Patent Document 1 below discloses a method using an imprint technique as a method for forming a dual damascene structure. In the imprint method, it is possible to transfer a three-dimensional structure pattern formed on a mold, so it is also possible to transfer a multi-stage structure pattern. Thereby, since the number of necessary processes can be reduced, there is an increasing demand for an imprint mold having a multistage structure.

In addition, it is known that a method for forming a fine three-dimensional structure pattern is used for manufacturing an imprint mold for transferring a fine three-dimensional structure pattern.
Further, as a method for manufacturing a specific fine three-dimensional structure pattern (for example, a multi-step staircase structure), a method of forming a staircase structure using charged particle beam lithography is known.

In the lithography method, it is known that a drawn resist pattern collapses in a development process after exposure. It is known that the collapse of the resist pattern is more likely to occur as the pattern has a higher aspect ratio.
For example, Patent Document 2 below discloses a method of suppressing collapse of a resist pattern by forming a bridge on a resist surface layer.
Further, it is known that a fine three-dimensional structure pattern is formed by patterning a resist a plurality of times in accordance with the three-dimensional pattern.

  At this time, as shown in FIG. 2, the resist film 44 cannot be flatly coated on the entire surface including the hard mask pattern 36 on the substrate 37 on which the one-step pattern is formed. If patterning is performed on the resist film 44 that is not flat, the positional accuracy of the resist pattern is lowered, so that it is difficult to form a desired resist pattern. Further, as shown in FIG. 3A, when the resist film 44 is thickened so that the resist film 44 becomes flat, the aspect ratio of the formed resist pattern 55 becomes high. As shown, the resist pattern 55 collapses and it is difficult to obtain a desired resist pattern.

In general, since a resist film is an insulator, when drawing with an electron beam, a negative charge is induced on the surface of the resist film by an electron beam having a negative charge, and the negative charge cannot be discharged. Negative charges are accumulated on the surface, and the accumulated negative charges cause the electron beam to bend near the resist film surface, resulting in a misalignment in drawing. It is difficult to pattern the resist film.
In addition, when a step is formed on an insulating substrate by performing anisotropic etching on the insulating substrate using the conductive hard mask layer as an etching mask, there is no hard mask layer in the concave portion of the step. In the process of newly patterning a resist on a substrate provided with the above, drawing misalignment due to accumulation of negative charges becomes a problem.

Hereinafter, an example of a conventional typical multi-stage pattern forming method will be described with reference to FIG.
First, as shown in FIG. 4A, a substrate 31 provided with a hard mask layer 32 is coated with a resist to form a first resist film 34.
Next, as shown in FIG. 4B, the first resist film 34 is patterned to form a first resist pattern 35.
Next, as shown in FIG. 4C, the hard mask layer 32 is etched using the first resist pattern 35 as a mask to form a first hard mask pattern 36.

Next, as shown in FIG. 4D, the substrate 31 is etched and washed using the first hard mask pattern 36 as a mask to produce a substrate 37 on which a one-step pattern is formed.
Next, as shown in FIG. 4E, a second resist film 44 is formed by coating a resist again on the substrate 37 on which a one-step pattern is formed.
Next, as shown in FIG. 4F, the second resist film 44 is patterned to form a second resist pattern 45.

Next, as shown in FIG. 4G, the first hard mask pattern 36 is etched using the second resist pattern 45 as a mask to form a second hard mask pattern 46.
Next, as shown in FIG. 4H, the substrate 37 on which the one-step pattern is formed is etched using the etched second hard mask pattern 46 as a mask.

Next, as shown in FIG. 4 (i), the second hard mask pattern 46 is washed and peeled off to produce a substrate 47 on which a two-stage pattern is formed.
In this conventional typical multi-stage pattern forming method, since the substrate already has a step in the second resist patterning (see FIGS. 4E to 4F), as shown in FIG. Since the resist film cannot be coated flatly, it is difficult to obtain a desired resist pattern, which is unsuitable for forming a fine three-dimensional pattern.

In addition, since the Nth resist pattern is smaller than the (N-1) th formed pattern, a fine resist pattern is formed on a resist on a substrate already provided with a step as the level difference of the multi-step structure increases. Therefore, it is difficult to obtain a desired resist pattern, which is not suitable for forming a fine three-dimensional structure pattern.
Further, there is no hard mask layer in the concave portion of the step on the substrate on which the first step pattern is formed. Therefore, in the second resist patterning step (see FIGS. 4E to 4F), the negative charge induced in the resist by the electron beam is not discharged, and the negative charge is accumulated on the resist film surface. Since the electron beam is bent near the resist film surface due to the negative charge and the positional deviation of drawing occurs, it is unsuitable for forming a fine three-dimensional structure pattern.
For example, Patent Document 3 below discloses a method of forming a step in a hard mask layer formed on a substrate in order to suppress the occurrence of resist pattern collapse.

Hereinafter, an example of a pattern forming method having a multi-stage structure using a hard mask layer having a step will be described with reference to FIG.
First, as shown in FIG. 5A, a first resist film 34 is formed by coating a resist on a substrate 31 provided with a hard mask layer 32.
Next, as shown in FIG. 5B, the first resist film 34 is patterned to form a first resist pattern 35.
Next, as shown in FIG. 5C, the hard mask layer 32 is etched using the first resist pattern 35 as a mask to form a first hard mask pattern 36.
Next, as shown in FIG. 5D, the first resist pattern 35 is washed and peeled off.

Next, as shown in FIG. 5E, a resist is coated again on the substrate 31 on which the first hard mask pattern 36 is formed to form a second resist film 44.
Next, as shown in FIG. 5 (f), the second resist film 44 is patterned to form a second resist pattern 45.
Next, as shown in FIG. 5G, the first hard mask pattern 36 is etched using the second resist pattern 45 as a mask to form a hard mask pattern 56 having a step.

Next, as shown in FIG. 5H, using the hard mask pattern 56 having a step as a mask, the substrate 31 is etched, the second resist pattern 45 is washed, and peeled to form a one-step pattern. The formed substrate 37 is produced.
Next, as shown in FIG. 5I, the hard mask pattern 56 having a step is etched to form a second hard mask pattern 46.
Next, as shown in FIG. 5J, the substrate 37 on which the one-step pattern is formed is etched using the second hard mask pattern 46 as a mask.

Next, as shown in FIG. 5 (k), the second hard mask pattern 46 is washed and peeled off to produce a substrate 47 on which a two-stage pattern is formed.
In the pattern forming method having the multi-stage structure including the hard mask layer having the step, the conductive hard mask layer is formed on the substrate in the second resist patterning step (FIGS. 5E to 5F). Since it exists only in a part, the negative charge induced in the resist by the electron beam is not discharged, the negative charge accumulates on the resist film surface, the electron beam is bent near the resist film surface by the negative charge, and the drawing position Since deviation occurs, it is not suitable for forming a fine three-dimensional structure pattern.

  In addition, when a step is formed in the hard mask layer by performing dry etching, the etching of the hard mask layer proceeds faster in the shoulder portion of the pattern than in the flat portion. 6 (a) does not become a rectangle as shown in FIG. 6 (b), and it is difficult to form a step on the substrate with high dimensional accuracy. Not suitable for formation.

Special table 2007-521645 gazette JP 2004-085792 A JP 2009-111241 A

  An object of this invention is to provide the pattern formation method and pattern formation body suitable for formation of the fine three-dimensional structure pattern provided with the several level | step difference.

  According to a first aspect of the present invention, a first hard mask layer is formed on a substrate, and the first layer is provided on a surface of the substrate having the first hard mask layer. The etch stopper layer is formed, and the hard mask layer from the second layer to the Nth layer and the second layer to the (( N-1) Etch stopper layers up to the first layer are alternately formed, patterning processing of the Nth hard mask layer is performed, and etch stoppers from the (N-1) th layer to the first layer are performed. Layer and the hard mask layers from the (N-1) th layer to the first layer are alternately patterned, and the hard mask layers from the first layer to the Nth layer are etched. As a mask, the substrate is patterned by first-stage anisotropic etching. It is a pattern forming method comprising. In the present invention, N is a natural number of 2 or more.

The line width of the pattern formed on the (N-1) th hard mask layer may be larger than the line width of the pattern formed on the Nth hard mask layer. The pattern forming method according to claim 1, wherein the pattern forming method is large.
The invention according to claim 3 includes a step of performing patterning processing from the second stage to the Nth stage in order on the side of the substrate on which the first stage pattern is formed, 3. The pattern forming method according to claim 1, wherein a line width of the N-th pattern is smaller than a line width of the (N−1) -th pattern.

According to a fourth aspect of the present invention, the substrate is a quartz substrate, and the hard mask layers from the first layer to the Nth layer are layers made of chromium, and from the first layer 4. The pattern forming method according to claim 1, wherein the etch stopper layers up to the (N-1) th layer are layers made of silicon.
The invention according to claim 5 is a pattern forming body formed by using the pattern forming method according to any one of claims 1 to 4.

  ADVANTAGE OF THE INVENTION According to this invention, the pattern formation method and pattern formation body suitable for formation of the fine three-dimensional structure pattern provided with the several level | step difference can be provided.

It is a schematic sectional drawing which shows an example of the pattern formation method which concerns on the Example of this invention. It is a schematic sectional drawing which shows the problem in the conventional pattern formation method. It is a schematic sectional drawing which shows the problem in the conventional pattern formation method. It is a schematic sectional drawing which shows an example of the conventional pattern formation method. It is a schematic sectional drawing which shows an example of the conventional pattern formation method. It is a schematic sectional drawing which shows the problem in the conventional pattern formation method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Step (A) of Forming First Hard Mask Layer 12, Etch Stopper Layer 13, and Second Hard Mask Layer 22 on Substrate 11> (See FIG. 1A)
First, the first hard mask layer 12 is formed on the substrate 11. As a method for forming the first hard mask layer 12, a known thin film forming technique may be used as appropriate according to the material selected for the first hard mask layer 12. For example, a sputtering method or the like may be used.
The substrate 11 may be appropriately selected according to the application. As the substrate 11, for example, a silicon substrate, a quartz substrate, a sapphire substrate, an SOI substrate, or the like may be suitably used.
The first hard mask layer 12 may be any conductive material having a high etching selectivity with respect to the substrate 11 and the etch stopper layer 13.

Next, an etch stopper layer 13 (first layer) is formed on the surface of the substrate 11 on which the first hard mask layer 12 is formed. As a method for forming the etch stopper layer, a known thin film forming technique may be used as appropriate according to the material selected for the etch stopper layer. For example, a sputtering method or the like may be used.
The etch stopper layer may be a material having a high etching selectivity with respect to the first hard mask layer 12 and the second hard mask layer 22.

Next, a second hard mask layer 22 is formed on the surface of the substrate 11 on which the etch stopper layer 13 is formed. As a method of forming the second hard mask layer 22, a known thin film forming technique may be used as appropriate according to the material selected for the second hard mask layer 22. For example, a sputtering method or the like may be used.
The second hard mask layer 22 may be any conductive material having a high etching selectivity with respect to the etch stopper layer 13.

  Here, for example, when a quartz substrate is used as the substrate 11, the first hard mask layer 12 is made of Cr (chrome), the etch stopper layer is made of Si (silicon), and the second layer. It is preferable to use a layer made of chromium as the eye hard mask layer. The quartz substrate is transmissive to general exposure light. In particular, the pattern forming method of the present invention is applied to the manufacturing process of an imprint mold or a photomask used for the optical imprint method. It is suitable for use.

  In lithography using the resist film 24 in <step (C) of patterning the first hard mask layer 12>, which will be described later, by using a layer made of chromium for the first hard mask layer 12 In the patterning of the first hard mask layer 12, the first hard mask layer 12 is etched with respect to the substrate 11 under general etching conditions. The selection ratio can be set high. Further, in <step (D) of performing first-stage anisotropic etching on substrate 11> and <step (F) of performing second-stage anisotropic etching on substrate 11> described later, Under the etching conditions, the etching selectivity of the substrate 11 with respect to the first hard mask layer 12 can be set high. Further, in <step (E) of performing anisotropic etching on the first hard mask pattern 16> described later, the first hard mask layer 12 is formed on the substrate 11 and the etch stopper under general etching conditions. The etching selectivity can be set higher with respect to the layer 13.

Further, by using a layer made of silicon for the etch stopper layer 13, a general etching process for the etch stopper layer 13 in the <step (B) of patterning the second hard mask layer 22>, which will be described later, is used. Under the etching conditions, the etching stopper layer 13 can be set to have a higher etching selectivity than the first hard mask layer 12.
In addition, by using a layer made of chromium for the second hard mask layer 22, the first resist film 14 in the <step (B) of patterning the second hard mask layer 22> described later is used. In the lithography using, the accumulation of negative charges due to the electron beam can be prevented, and the second hard mask layer 22 is subjected to general etching conditions in the patterning of the second hard mask layer 22. The etching selectivity with respect to the etch stopper layer 13 can be set high.

<Step of Patterning Second Hard Mask Layer 22 (B)>
Next, the second hard mask layer 22 is patterned. As a method of patterning the second hard mask layer 22, lithography using the first resist film 14 is used. For example, in patterning the second hard mask layer 22, the first resist film 14 is formed on the second hard mask layer 22 (FIG. 1B). Next, the first resist film 14 is patterned to form a first resist pattern 15 (FIG. 1C). Next, by etching using the first resist pattern 15 as a mask, the second hard mask layer 22 is patterned to form a second hard mask pattern 26 (FIG. 1D). ). After patterning the second hard mask layer 22, the etch stopper layer 13 is etched using the second hard mask pattern 26 as a mask (FIG. 1 (e)). The resist pattern 15 is cleaned and peeled off (FIG. 1 (f)).

  At this time, the line width of the second-layer hard mask pattern 26 is set to be the first-layer hard mask pattern 16 formed in <Step (C) of patterning the first-layer hard mask layer 12> to be described later. Is smaller than the line width. For this reason, the finest pattern among the plurality of patterns can be formed by lithography using the flat first resist film 14 formed on the substrate having no step, and the hard mask layer 22 is formed. A pattern can be formed with high accuracy.

Here, in the patterning of the hard mask layer 22, the second hard mask layer 22 is made of a material having a high etching selectivity with respect to the etch stopper layer 13. The shape can be rectangular. For this reason, a pattern can be formed on the substrate 11 with high dimensional accuracy.
In the etching of the etch stopper layer 13, the etch stopper layer 13 is a material having a high etching selectivity with respect to the first hard mask layer 12, so that the cross-sectional shape of the patterned etch stopper layer 13 'is changed. It can be rectangular. For this reason, a pattern can be formed on the substrate 11 with high dimensional accuracy.

<Step of Patterning First Hard Mask Layer 12 (C)>
Next, the first hard mask layer 12 is patterned. As a method for patterning the first hard mask layer 12, a lithography method using the second resist film 24 is used. For example, in the patterning of the first hard mask layer 12, the second resist film 24 is formed on the substrate 11 including the second hard mask pattern 26 (FIG. 1G). Next, the second resist film 24 is patterned to form a second resist pattern 25 (FIG. 1H). Next, by etching using the second resist pattern 25 as a mask, the first hard mask layer 12 is patterned to form the first hard mask pattern 16 (FIG. 1I). ). After patterning the first hard mask layer 12, the second resist pattern 25 is washed and peeled off (FIG. 1 (j)).

  Here, in the patterning of the second resist film 24, since the line width of the already formed second layer hard mask pattern 26 is sufficiently fine, the second resist film 24 has sufficient flatness. Can be coated. For this reason, the positional accuracy of the patterning of the second resist film 24 can be improved without increasing the thickness of the second resist film 24, the collapse of the second resist pattern 25 can be suppressed, and the desired pattern can be accurately obtained. Can get well.

Further, in the patterning of the second resist film 24, the negative charge induced in the resist by the electron beam is discharged through the first hard mask layer 12. For this reason, negative charges are not accumulated in the second resist film 24, and it is possible to prevent misalignment of drawing in the patterning of the second resist film 24 and to perform drawing with high accuracy.
Further, since the first hard mask layer 12 is made of a material having a high etching selectivity with respect to the substrate 11, the cross-sectional shape of the first hard mask pattern 16 can be rectangular. For this reason, a pattern can be formed on the substrate 11 with high dimensional accuracy.

<Step (D) of performing first-stage anisotropic etching on substrate 11>
Next, anisotropic etching is performed on the substrate 11 from the side on which the first-layer hard mask pattern 16 is formed on the substrate 11 (FIG. 1 (k)). As the etching, a known etching method may be used as appropriate. For example, dry etching, wet etching, or the like may be used. Etching conditions may be appropriately adjusted according to the materials of the first hard mask layer 12, the second hard mask layer 22, and the substrate 11 used. At this time, a step having a line width larger than the line width of the second-layer hard mask pattern 26 is formed on the substrate 11 in accordance with the line width of the first-layer hard mask pattern 16.

<Step (E) of performing anisotropic etching on hard mask pattern 16 of first layer>
Next, anisotropic etching of the hard mask pattern 16 of the first layer is performed (FIG. 1L). As the etching, a known etching method may be used as appropriate, for example, dry etching, wet etching, or the like may be performed. Etching conditions may be appropriately adjusted according to the materials of the first hard mask layer 12, the etch stopper layer 13, the second hard mask layer 22, and the substrate 11 used.

  Here, since the hard mask pattern 16 of the first layer is a material having a high etching selectivity with respect to the substrate 11 and the etch stopper layer 13, the cross-sectional shape of the etched hard mask pattern 16 ′ of the first layer is changed. It can be rectangular. For this reason, a pattern can be formed on the substrate 11 with high dimensional accuracy.

<Step (F) of performing second-stage anisotropic etching on substrate 11>
Next, anisotropic etching is performed on the substrate 17 on which the first-stage pattern is formed from the side on which the first-layer hard mask pattern 16 'is formed on the substrate 17 on which the first-stage pattern is formed (see FIG. 1 (m)). As the etching, a known etching method may be used as appropriate, and for example, dry etching, wet etching, or the like may be used. Etching conditions may be adjusted as appropriate depending on the materials of the first hard mask layer 12 and the substrate 11 used. At this time, the first-stage anisotropic etching is performed on the substrate 11 on the substrate 17 on which the first-stage pattern is formed according to the line width of the second-layer hard mask pattern 26 described above. In (D)>, a step having a larger line width than the step formed on the substrate 11 is formed.

  Further, the formation of the etch stopper layer and the formation of the hard mask layer are repeated in the step (A) to form three or more N hard mask layers, and the Nth layer in the steps (B) and (C). By patterning the hard mask layer from the first layer to the first layer and repeating the above steps (D) to (F), the three-dimensional structure pattern to be formed on the substrate is not only two steps but also three or more steps. A (N-stage) structure pattern can be obtained.

Then, after the steps (A) to (F), the patterned etch stopper layer 13 ′ and the first hard mask pattern 16 ′ are subjected to wet peeling cleaning, thereby achieving high positional accuracy and dimensional accuracy. An imprint mold is produced.
In addition, a photomask with high positional accuracy and dimensional accuracy can be manufactured from the pattern forming body manufactured by the above steps (A) to (F).

  Moreover, according to the present invention, resist patterning can be performed in order from the finest pattern among the multi-stage structure patterns. For this reason, a fine three-dimensional structure pattern having a plurality of steps can be suitably formed.

Hereinafter, the pattern forming method of the embodiment of the present invention will be described with reference to FIG. 1 while giving an example in the case of producing an optical imprint mold. The pattern forming method of the embodiment of the present invention is not limited to the following embodiment.
First, a quartz substrate was used as the substrate 11 as shown in FIGS. A first Cr layer 12 having a Cr film thickness of 30 nm formed on the quartz substrate 11 as a first hard mask layer, a Si layer 13 having a Si film thickness of 20 nm formed as an etch stopper layer, and a second layer A second Cr layer 22 having a Cr film thickness of 30 nm was sequentially formed as a hard mask layer, and a positive resist FEP-171 (FUJIFILM Electronics Materials Co., Ltd.) was formed on the second Cr layer 22. (Manufactured) The first resist film 14 was coated to a thickness of 200 nm.

Next, as shown in FIG. 1C, after the electron beam is irradiated to the first resist film 14 at a dose of 10 μC / cm ² with an electron beam drawing apparatus, a developing process using a developer is performed. The first resist pattern 15 was obtained by rinsing and drying the rinse solution. Here, a TMAH aqueous solution was used as a developing solution, and pure water was used as a rinsing solution.
Next, as shown in FIG. 1D, the second layer Cr layer 22 was etched by dry etching using an ICP dry etching apparatus to obtain a second layer Cr pattern 26. At this time, the etching conditions for the _second Cr layer 22 were Cl ₂ flow rate 40 sccm, O ₂ flow rate 10 sccm, He flow rate 80 sccm, pressure 30 Pa, ICP power 120 W, and RIE power 50 W.

At this time, since the second Cr layer 22 is a material having a higher etching selectivity than the Si layer 13, the tailing of the second Cr pattern 26 can be reduced. The cross-sectional shape of the eye Cr pattern 26 can be rectangular. For this reason, a pattern can be formed on the quartz substrate 11 with high dimensional accuracy.
Next, as shown in FIG. 1E, the Si layer 13 was etched by dry etching using an ICP dry etching apparatus to obtain a patterned Si layer 13 ′. At this time, the etching conditions for the Si layer 13 were CF ₄ flow rate 30 sccm, C ₄ F ₈ flow rate 20 sccm, pressure 30 Pa, ICP power 500 W, and RIE power 50 W.
At this time, since the Si layer 13 is a material having a high etching selectivity with respect to the first Cr layer 12, the tailing of the patterned Si layer 13 ′ can be reduced, and the patterned Si layer 13 can be reduced. The cross-sectional shape of the layer 13 ′ can be rectangular. For this reason, a pattern can be formed on the quartz substrate 11 with high dimensional accuracy.

Next, as shown in FIG. 1F, the resist pattern 15 was removed by O ₂ plasma ashing (conditions: O ₂ flow rate 500 sccm, pressure 30 Pa, RIE power 1000 W).

From the above, as shown in FIG. 1 (f), the second layer Cr pattern 26 could be formed on the first layer Cr film 12 on the quartz substrate 11.
Next, as shown in FIG. 1 (g), a positive resist having a thickness of 200 nm is coated on the quartz substrate 11 provided with the first layer Cr film 12 and the second layer Cr pattern 26, The resist film 24 was obtained.

  Since the patterned Si layer 13 'and the second layer Cr pattern 26 are low in height, the second resist film 24 can be coated with sufficient flatness. For this reason, the positional accuracy of the patterning of the second resist film 24 can be improved without increasing the thickness of the second resist film 24, the collapse of the second resist pattern 25 can be suppressed, and the desired pattern can be accurately obtained. Can get well.

Next, as shown in FIG. 1 (h), the second resist film 24 is irradiated with an electron beam at a dose of 10 μC / cm ² with an electron beam lithography apparatus, and then developed with a developer. The second resist pattern 25 was obtained by rinsing and drying the rinse solution. Here, a TMAH aqueous solution was used as a developing solution, and pure water was used as a rinsing solution.
In the patterning of the second resist film 24, negative charges induced in the resist by the electron beam are discharged through the first Cr film 12. For this reason, negative charges are not accumulated in the second resist film 24, and it is possible to prevent misalignment of drawing in the patterning of the second resist film 24 and to perform drawing with high accuracy.

Next, as shown in FIG. 1 (i), the first Cr layer 12 was etched by dry etching using an ICP dry etching apparatus to obtain the first Cr pattern 16. At this time, the etching conditions for the first Cr layer 12 were Cl ₂ flow rate 40 sccm, O ₂ flow rate 10 sccm, He flow rate 80 sccm, pressure 30 Pa, ICP power 120 W, and RIE power 50 W.
At this time, since the first Cr layer 12 is made of a material having a high etching selectivity with respect to the substrate 11, the bottom of the first layer Cr pattern 16 can be reduced. The cross-sectional shape of the Cr pattern 16 can be rectangular. For this reason, a pattern can be formed on the quartz substrate 11 with high dimensional accuracy.
Next, as shown in FIG. 1J, the second resist pattern 25 was peeled off by O ₂ plasma ashing (conditions: O ₂ flow rate 500 sccm, pressure 30 Pa, RIE power 1000 W).

From the above, as shown in FIG. 1 (j), the first layer Cr pattern 16 could be formed on the quartz substrate.
Next, as shown in FIG. 1 (k), the quartz substrate 11 was etched by dry etching using an ICP dry etching apparatus. At this time, the etching conditions for the quartz substrate 11 were C ₄ F ₈ flow rate 10 sccm, O ₂ flow rate 10 sccm to 25 sccm, Ar flow rate 75 sccm, pressure 2 Pa, ICP power 20 W, and RIE power 550 W.

At this time, since the quartz substrate 11 is a material having a high etching selection ratio with respect to the first layer Cr pattern 16, the quartz substrate 11 is etched with almost no change in the dimension of the first layer Cr pattern 16. can do. For this reason, a pattern can be formed on the quartz substrate 11 with high dimensional accuracy.
From the above, as shown in FIG. 1 (k), the quartz substrate 17 on which the first-stage pattern was formed could be produced.

Next, as shown in FIG. 1L, the first layer Cr pattern 16 was etched by dry etching using an ICP dry etching apparatus. At this time, the etching conditions for the first layer Cr pattern 16 were Cl ₂ flow rate 40 sccm, O ₂ flow rate 10 sccm, He flow rate 80 sccm, pressure 30 Pa, ICP power 120 W, and RIE power 50 W. At this time, the second layer Cr pattern 26 was also etched, and the second layer Cr pattern 26 disappeared.

  Since the first layer Cr pattern 16 is a material having a high etching selectivity with respect to the patterned Si layer 13 ', even if the second layer Cr pattern 26 disappears during the etching, the patterned Si layer The dimension of the layer 13 ′ hardly changes, and the cross-sectional shape of the etched first layer Cr pattern 16 ′ can be rectangular. In addition, since the first layer Cr pattern 16 is a material having a high etching selectivity with respect to the quartz substrate 11, it is possible to reduce the trailing edge of the etched first layer Cr pattern 16 ′. The cross-sectional shape of the first layer Cr pattern 16 ′ can be rectangular. For this reason, a pattern can be formed on the quartz substrate 11 with high dimensional accuracy.

Next, as shown in FIG. 1M, the quartz substrate 17 on which the one-step pattern was formed was etched by dry etching using an ICP dry etching apparatus. At this time, the etching conditions for the quartz substrate 17 on which the one-step pattern was formed were C ₄ F ₈ flow rate 10 sccm, O ₂ flow rate 10 sccm to 25 sccm, Ar flow rate 75 sccm, pressure 2 Pa, ICP power 20 W, RIE power 550 W. . At this time, the patterned Si layer 13 ′ was also etched, and the patterned Si layer 13 ′ disappeared.

Since the quartz substrate 17 on which the one-step pattern is formed is a material having a high etching selectivity with respect to the etched first layer Cr pattern 16 ′, the patterned Si layer 13 ′ disappears during the etching. Even in this case, the quartz substrate 17 on which the one-step pattern is formed can be etched without substantially changing the dimension of the etched first layer Cr pattern 16 '. For this reason, a pattern can be formed with high dimensional accuracy on the quartz substrate 17 on which a one-step pattern is formed.
From the above, as shown in FIG. 1 (m), a quartz substrate 27 on which a two-step pattern was formed could be produced.

Next, as shown in FIG. 1 (n), the remaining etched Cr pattern 16 ′ of the first layer was wet-cleaned. As a result, a quartz substrate 27 having a two-stage pattern was obtained.
As mentioned above, the imprint mold for optical imprints with high dimensional accuracy was able to be manufactured using the pattern formation method in the Example of this invention.

  The pattern forming method of the present invention is expected to be used in a wide range of fields where a fine pattern is required. For example, imprint molds, photomasks, semiconductor devices, optical elements, wiring circuits (such as a dialer machine structure wiring circuit), recording devices (such as hard disks and DVDs), medical test chips (such as DNA analysis applications) ), Displays (diffusion plates, light guide plates, etc.), microchannels, etc. are expected.

11 ... substrate 12 ... first hard mask layer (Cr layer)
13 ... Etch stopper layer (Si layer)
13 '... Patterned etch stopper layer (Si layer)
DESCRIPTION OF SYMBOLS 14 ... 1st resist film 15 ... 1st resist pattern 16 ... Hard mask pattern (Cr pattern) of the 1st layer
16 '... etched first layer hard mask pattern (Cr pattern)
17 ... Substrate on which one-step pattern is formed 22 ... Second hard mask layer (Cr layer)
24 ... second resist film 25 ... second resist pattern 26 ... second layer hard mask pattern (Cr pattern)
27 ... Substrate on which a two-step pattern is formed 31 ... Substrate 32 ... Hard mask layer 34 ... First resist film 35 ... First resist pattern 36 ... First Hard mask pattern 37 ... Substrate on which a one-step pattern is formed 44 ... Second resist film 45 ... Second resist pattern 46 ... Second hard mask pattern 47 ... Two steps Substrate on which a pattern of 55 is formed 55 ... A collapsed resist pattern 56 ... A hard mask pattern with a step

Claims (5)

Forming a first hard mask layer on the substrate;
Forming a first etch stopper layer on the surface of the substrate having the first hard mask layer;
On the surface having the first etch stopper layer on the substrate, a hard mask layer from the second layer to the Nth layer, and a layer from the second layer to the (N-1) th layer Alternately formed etch stopper layers,
Patterning the Nth hard mask layer;
The etching stopper layer from the (N-1) th layer to the first layer and the hard mask layer from the (N-1) th layer to the first layer are alternately patterned,
A pattern forming method comprising patterning a first step of anisotropic etching on the substrate using the patterned hard mask layers from the first layer to the Nth layer as an etching mask.   The line width of the pattern formed in the (N-1) th hard mask layer is larger than the line width of the pattern formed in the Nth hard mask layer. Pattern forming method. A patterning process from the second stage to the Nth stage in order on the side of the substrate on which the first stage pattern is formed,
3. The pattern forming method according to claim 1, wherein a line width of the Nth stage pattern is smaller than a line width of the (N−1) th stage pattern. The substrate is a quartz substrate;
The hard mask layers from the first layer to the Nth layer are layers made of chromium,
4. The pattern forming method according to claim 1, wherein the etch stopper layers from the first layer to the (N−1) th layer are layers made of silicon. 5.   A pattern forming body formed by using the pattern forming method according to claim 1.

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