JP2012209397A - 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 that are suitable to formation of a fine and uniform pattern.SOLUTION: The uniform pattern can be formed on a substrate by making a region where a resist pattern is formed larger than a region of a step formed on a hard mask layer, and subjecting the hard mask layer to anisotropic etching so that the hard mask layer is left at an upper stage part of a hard mask so as to cover a substrate surface, and a part of the substrate surface is exposed at a lower stage part.

Description

  The present invention relates to a pattern forming method suitable for forming a fine and uniform pattern, and a pattern forming body formed using the pattern forming method.

  In recent years, there is a demand for a method for forming a specific fine uneven pattern according to various applications. Examples of the technology for forming such fine concavo-convex patterns include semiconductor devices, optical elements, wiring circuits, data storage media (hard disks, optical media, etc.), medical members (analytical inspection chips, microneedles, etc.), biotechnology, etc. Devices (biosensors, cell culture substrates, etc.), precision inspection equipment members (inspection probes, sample holding members, etc.), display panels, panel members, energy devices (solar cells, fuel cells, etc.), microchannels, microreactors, MEMS Applications such as devices, imprint molds and photomasks can be mentioned.

  As a method of forming a fine pattern as described above, a method of drawing a pattern on a resist using an electron beam drawing machine is known (for example, see Patent Document 1).

  In the case of exposure with an electron beam, fogging occurs in an area where the pattern is dense.

  Fogging means that electrons struck onto the substrate from the electron gun of the drawing machine are scattered and reflected on the surface of the substrate, etc., and some electrons jump out of the resist surface and further reflect on the inner wall of the drawing machine chamber. In this case, the light is incident on the resist again. The higher the pattern density, the greater the influence of fogging, and the area affected by fogging may reach several tens of millimeters. It is known that this resist is slightly sensitized by the energy of re-incident electrons caused by fogging, and the pattern affected by the fogging undergoes a change in dimensions (see, for example, Patent Document 2).

JP 2000-182941 A JP 2008-78553 A

  However, in the above-described forming method, when forming a fine and uniform pattern, if a part where the dimension has changed due to the effect of fogging and a part where the dimension does not change without being affected by the fogging are generated, the dimension within the resist pattern surface Becomes non-uniform. In particular, a dimensional difference appears remarkably between the pattern outer periphery and the center. When the hard mask layer or the substrate is etched using this resist pattern as a mask, there is a problem that a pattern having a uniform in-plane dimension cannot be formed.

  In addition, it is difficult to newly perform resist patterning on a substrate that already has a step because of the following reasons. It goes without saying that the greater the depth of the step, the higher the difficulty.

  First, when a resist is coated on a stepped substrate, if the thickness of the resist film is equal to or less than the step, the resist film on the convex portion becomes thin, and a flat resist film is obtained. I can't. For this reason, it is difficult to obtain a desired resist pattern.

  Secondly, when the resist film is sufficiently thick so that the resist film is flat, the aspect ratio of the formed resist pattern is increased according to the thickness of the resist film, so that the resist pattern collapses. For this reason, it is difficult to obtain a desired resist pattern.

  In particular, when forming a desired pattern after forming a step, there is a problem that when the electron beam is irradiated for the desired pattern, the substrate itself is charged and it is difficult to accurately draw the pattern.

  SUMMARY An advantage of some aspects of the invention is to provide a pattern forming method and a pattern forming method suitable for forming a fine and uniform pattern.

  The invention according to claim 1 includes a step of forming a hard mask layer on a substrate, a step of forming a step on the hard mask layer, a step of forming a resist layer on the hard mask layer having the step formed thereon, and the resist Forming a uniform pattern on the layer; performing anisotropic etching on the hard mask layer using the patterned resist layer as an etching mask; and using the patterned hard mask layer as an etching mask to form the substrate. And a step of performing anisotropic etching, wherein the region where the resist pattern is formed is a pattern forming method configured to be set larger than the stepped region formed in the hard mask layer.

  Further, in the invention according to claim 2, in the step of performing anisotropic etching on the hard mask layer, the upper part of the hard mask in which the step is formed leaves the hard mask so as to cover the substrate surface, and The lower step portion of the hard mask in which the step is formed is in a pattern forming method in which a part of the substrate surface is exposed.

  According to a third aspect of the present invention, in the step of forming a step in the hard mask layer, the hard mask layer is left so as to cover the substrate surface.

  Moreover, the invention which concerns on Claim 4 exists in the pattern formation body produced with the pattern formation method by Claims 1-3.

  According to the present invention, the region where the resist pattern is formed is larger than the step region formed in the hard mask layer, and the hard mask is left so that the upper step of the hard mask covers the substrate surface, and the lower step By performing anisotropic etching on the hard mask layer so that the substrate surface is partially exposed, a uniform pattern can be formed on the substrate. Further, since the Fogging correction is not necessary, a process such as setting Fogging conditions is not necessary.

  Further, in the step of forming a step in the hard mask layer, since the hard mask layer is a material having a high etching selectivity with respect to the substrate, the step of the hard mask layer to be formed has a smaller depth than the desired pattern. I can do it. In addition, by leaving the hard mask layer so as to cover the substrate surface, charging (charging up) of the substrate can be suppressed in resist pattern formation.

It is the general | schematic process drawing which showed the principal part in cross section in order to demonstrate the procedure of the pattern formation method which concerns on one embodiment of this invention. It is the general | schematic process drawing which cut and showed the principal part, in order to demonstrate the preparation procedure by the imprint method using the pattern formation body which concerns on one embodiment of this invention as an imprint mold.

  Hereinafter, a pattern forming method and a pattern forming body according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a procedure of a pattern forming method for forming a pattern forming body according to an embodiment of the present invention.

  That is, first, the hard mask layer 12 is formed on the substrate 11 in the step of forming the hard mask layer 12 (see FIG. 1A). As a formation method of this hard mask layer 12, according to the material selected for the hard mask layer 12, it forms suitably using a well-known thin film formation method. For example, a sputtering method is used.

  The substrate 11 may be appropriately selected according to the application. For example, a silicon substrate, a quartz substrate, a sapphire substrate, an SOI substrate, or the like is used. The hard mask layer 12 may be made of a material having a high etching selection ratio in the step of performing anisotropic etching on the substrate 11 described later with respect to the selected substrate 11.

  The substrate 11 is preferably a quartz substrate, and the hard mask layer 12 is preferably a layer made of chromium. The quartz substrate is transmissive to general exposure light, particularly when the pattern forming method of the present invention is used for manufacturing processes such as an imprint mold used in the photoimprint method and a photomask. Is preferred. At this time, by using a layer made of chromium as the hard mask layer 12 with respect to the quartz substrate, the etching selectivity of the hard mask layer 12 with respect to the substrate 11 can be set high under general etching conditions.

  Next, the process proceeds to a step of forming a step in the hard mask layer 12 to form the hard mask pattern 15, and a resist material 13 is applied to form a step in the hard mask layer 12 (FIGS. 1A and 1B). (See (c)). At this time, the step region formed in the hard mask layer 12 is made equal to the region of the desired pattern.

  As a method for forming a step in the hard mask layer 12, a photolithography method using a resist, an electron beam drawing method, or the like is used. For example, a resist film is formed on the hard mask layer 12, the resist film is patterned, a resist pattern mask 14 is formed, and etching is performed using the resist pattern mask 14 as a mask. A step may be formed.

  Here, since the hard mask layer 12 is made of a material having a high etching selectivity with respect to the substrate 11, the step of the hard mask layer 12 corresponding to the pattern to be formed can be made smaller than the desired pattern height. . For this reason, resist pattern collapse can be suppressed. The steps formed on the hard mask layer 12 may be not only two steps but also more steps.

  Further, when forming a step in the hard mask layer 12, the hard mask layer 12 is left so as to cover the substrate surface. Thereby, in the formation of the resist pattern mask 14, charging (charge-up) of the substrate 11 can be suppressed.

  Next, the process proceeds to a step of coating the resist material 16, and the resist material 16 is coated on the substrate 11 having the hard mask pattern 15 (see FIG. 1D). The resist material 16 may be appropriately selected according to photolithography, electron beam, or the like for patterning. In addition, as a method for forming a coating film of the resist material 16, a known thin film forming technique may be appropriately used depending on the viscosity. For example, a die coating method, a spin coating method, or the like may be used.

  Subsequently, the process proceeds to a step of forming a resist pattern mask 17, and the resist pattern mask 17 is formed on the resist material 16 using an electron beam. After drawing, a development process is performed to form a resist pattern mask 17. The development treatment may be appropriately performed according to the resist film used. At this time, a cleaning process may be performed during the development process. The cleaning process only needs to be able to remove the developer / foreign matter, and may be performed using, for example, pure water or supercritical fluid. Further, a photolithography method may be used.

  The region where the resist pattern mask 17 is formed is made larger than the stepped region formed in the hard mask layer 12. Thereby, in the formation of the resist pattern mask 17, the outer peripheral portion in which the dimensional difference due to the influence of fogging is conspicuous as compared with the pattern central portion can be arranged outside the step region formed in the hard mask layer 12.

  Next, the process proceeds to a step of performing anisotropic etching on the hard mask layer 12, and the hard mask layer 12 is etched using the resist pattern mask 17 as a mask (see FIGS. 1E and 1F). Etching may be appropriately performed by a known method. For example, dry etching or wet etching may be performed.

  Here, the portion etched by the resist pattern mask 17 ′ formed in the upper step portion of the stepped hard mask layer 12 is formed in the lower step portion, leaving the hard mask layer 12 so as to cover the substrate surface. The portion etched by the resist pattern mask 17 ″ is subjected to anisotropic etching of the hard mask layer 12 so that part of the substrate surface is exposed. Etching conditions may be adjusted as appropriate according to the resist / substrate used.

  Subsequently, the process proceeds to a step of performing anisotropic etching on the substrate 11, and anisotropic etching is performed from the side on which the hard mask layer 12 is formed to form a pattern forming body 19 (FIGS. 1G and 1H). )reference). As an etching method, a known etching method may be used as appropriate, and for example, dry etching, wet etching, or the like may be performed. Etching conditions may be adjusted as appropriate according to the hard mask layer / substrate used.

  Here, the imprint method when the pattern forming body 19 formed by the above procedure is used as an imprint mold will be described with reference to FIG.

  First, in the step of performing an imprint method using an imprint mold, the transfer material 22 is laminated on the transfer substrate 21 (see FIG. 2A). The transfer substrate 21 can be appropriately selected so as to be suitable for the transfer material 22 to be used. Examples thereof include silicon and quartz glass.

  The transfer material 22 may be appropriately selected according to a desired uneven pattern, use of the uneven pattern, and the like. For example, a thermosetting resin, a photocurable resin, a sol-gel material, or the like may be used. In particular, a fluorine-based UV curable resin is desirable because of its excellent release properties. As a method for laminating the transfer material 22, a known thin film forming technique may be used as appropriate according to the viscosity of the transfer material. For example, a die coating method, a spin coating method, or the like may be used.

  Next, the transfer substrate 21 and the imprint mold are brought close to each other, and the pattern is transferred to the transfer material 22 to form a resin pattern 23 with a residual film, thereby forming a resin pattern 24 of the imprint mold (FIG. 2B). ) (C)). At this time, the imprint mold may be subjected to a mold release process. The transfer material 22 may be cured in accordance with the transfer material 22 and the desired pattern accuracy. For example, when a thermosetting resin is used as the transfer material 22, curing may be performed by heating. For example, when a photocurable resin is used as the transfer material 22, curing may be performed by exposure light.

  Subsequently, the transfer substrate 21 is etched using the resist pattern having the resin pattern 24 formed by this imprinting method as a mask to manufacture a replica 25 of the imprint mold with the concavities and convexities reversed (see FIG. 2D). .

  Here, for example, the process moves to the step of removing the remaining film, and the remaining film is removed according to the desired resin pattern 24. This remaining film is a transfer material 22 present between the transfer substrate 21 and the imprint mold, and refers to a portion where the transferred resin pattern 24 is not formed.

The removal of the remaining film may be performed using a suitable removal method depending on the selected transfer material 22. For example, when a thermosetting resin or a photocurable resin is used as the transfer material 22, it may be removed using an O ₂ (oxygen) RIE method. In addition, the O ₂ RIE conditions may be appropriately adjusted according to the resist / substrate used.

  And in the process of etching, you may carry out by a well-known method suitably as an etching. For example, dry etching, wet etching, or the like may be performed, and the etching conditions may be appropriately adjusted according to the resist / substrate used.

  Next, as a specific example of the pattern forming method of the present invention, an optical imprint mold was produced.

Example 1
First, a resist material 13 was coated to a thickness of 100 nm on a laminated substrate in which a hard mask layer 12 was formed to a thickness of 20 nm on the substrate 11 (see FIG. 1A). At this time, the substrate 11 is a quartz substrate, the hard mask layer 12 is a chromium film, and the resist material 13 is a positive electron beam resist.

  Next, after irradiating the resist material 13 with an electron beam by an electron beam drawing apparatus, development processing using a developer, rinsing, and drying of the rinsing liquid are performed to form a resist pattern mask 14 (FIG. 1 (b)). At this time, pure water was used as the rinse liquid.

  Next, using the resist pattern mask 14 as a mask, the hard mask layer 12 was etched by 10 nm by dry etching using an ICP dry etching apparatus, and a step was formed in the hard mask layer 12 to form a hard mask pattern 15 (FIG. 1 (c)). Further, the step region formed on the hard mask layer 12 was made equal to the region of the desired hard mask pattern 15.

At this time, the etching conditions of the chromium film as the hard mask pattern 15 were Cl ₂ flow rate 40 sccm, O ₂ flow rate 10 sccm, He flow rate 80 sccm, pressure 30 Pa, ICP power 300 W, and RIE power 30 W.

Next, the resist material 14 remaining on the substrate 11 on which the hard mask pattern 15 having the step was formed was peeled and washed. At this time, O ₂ ashing was used as peeling cleaning.

  Next, a resist material 16 was applied to a thickness of 100 nm on the substrate 11 on which the stepped hard mask pattern 15 was formed (see FIG. 1D).

  Next, after irradiating the resist material 16 with an electron beam by an electron beam drawing apparatus, development processing using a developer, rinsing, and drying of the rinsing liquid are performed to form a resist pattern mask 17 (FIG. 1 (e)). Pure water was used as the rinse liquid. At this time, the region where the resist pattern mask 17 was formed was made larger than the stepped region formed in the hard mask pattern 15.

  Next, using the resist pattern mask 17 as a mask, the hard mask pattern 15 in which a step is formed is etched by dry etching using an ICP dry etching apparatus, thereby forming a hard mask pattern 18 in which a desired pattern is formed (FIG. 1). (Refer to (f)).

  At this time, the portion etched by the resist pattern mask 17 ′ formed on the upper step portion of the hard mask pattern 15 having the step difference leaves the hard mask pattern 18 so as to cover the surface of the substrate 11, and the lower step portion. The hard mask pattern 18 is etched so that a portion of the surface of the substrate 11 is exposed at the portion etched by the resist pattern mask 17 ″ formed in the step.

The etching conditions of the chromium film, which is the hard mask pattern 15 with the step formed, were Cl ₂ flow rate 40 sccm, O ₂ flow rate 10 sccm, He flow rate 80 sccm, pressure 30 Pa, ICP power 300 W, and RIE power 30 W.

  Next, a pattern forming body 19 was formed by dry etching using an ICP dry etching apparatus with the hard mask pattern 18 having a desired pattern formed as a mask (see FIG. 1G).

At this time, the etching conditions of the quartz substrate as the substrate were a C ₄ F ₈ flow rate of 10 sccm, an O ₂ flow rate of 10 to 25 sccm, an Ar flow rate of 75 sccm, a pressure of 2 Pa, an ICP power of 200 W, and an RIE power of 550 W.

  Next, the hard mask pattern 18 on which a desired pattern was formed was peeled and cleaned (see FIG. 1 (h)). At this time, wet etching was used for removing and cleaning the hard mask layer 18 on which a desired pattern was formed.

  The pattern forming body 19 can be produced by the above procedure.

(Example 2)
The pattern forming body 19 produced in Example 1 was used as an imprint mold, and an impregnation method for forming a resin pattern 24 in which the concavo-convex pattern was inverted as shown in FIG. 2 was performed.

  First, a photocurable resin was laminated as a transfer material 22 on the transfer substrate 21 to a thickness of 100 nm, and the pattern forming body 19 was disposed facing the transfer material (see FIG. 2A).

  At this time, the surface of the pattern forming body 19 which is a fine imprint mold was previously coated with a fluorine-based surface treatment agent as a release agent. The transfer substrate 21 was a silicon substrate.

  Next, the transfer material 22 and the pattern forming body 19 are brought into contact, exposure light is irradiated from the pattern forming body 19 side, the transfer material 22 is cured, the transfer substrate 21 and the pattern forming body 19 are moved away, and the transfer material 22 is A resin pattern 23 with a remaining film was formed (see FIG. 2B).

  At this time, a load of 1 MPa was applied to the pattern forming body 19 which is a fine imprint mold, and the irradiation amount of UV light as exposure light was 400 mJ / cm 2.

  As described above, the fine resin pattern 23 in which the unevenness of the pattern forming body 19 produced in Example 1 is inverted is formed by the imprint method.

Next, the remaining film was removed by O ₂ plasma ashing (conditions: O ₂ flow rate 500 sccm, pressure 30 Pa, RF power 1000 W) to form a resin pattern 24 (see FIG. 2C).

Next, using the resin pattern 24 as a mask, the transfer substrate 21 was etched by dry etching using an ICP dry etching apparatus (see FIG. 2D). At this time, the etching conditions of the silicon substrate as the substrate were SF ₆ flow rate 40 sccm, Ar flow rate 75 sccm, pressure 2 Pa, ICP power 200 W, and RIE power 300 W.

  By the above procedure, a fine duplicated plate 25 in which the unevenness of the pattern forming body 19 which is a fine imprint mold produced in Example 1 is reversed can be produced.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention at the stage of implementation. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.

  For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problems described in the column of problems to be solved by the invention can be solved, and the effects described in the effects of the invention can be obtained. In some cases, a configuration from which this configuration requirement is deleted can be extracted as an invention.

  The pattern forming method and pattern forming body of the present invention include a semiconductor device, an optical element, a wiring circuit, a data storage medium (hard disk, optical medium, etc.), a medical member (analysis test chip, microneedle, etc.), a biodevice (bio Sensors, cell culture substrates, etc.), precision inspection equipment members (inspection probes, sample holding members, etc.), display panels, panel members, energy devices (solar cells, fuel cells, etc.), microchannels, microreactors, MEMS devices, etc. It can be expected to be usefully used for forming a fine pattern used in the manufacturing method.

DESCRIPTION OF SYMBOLS 11 ... Board | substrate 12 ... Hard mask layer 13, 16 ... Resist material 14, 17 ... Resist pattern mask 15, 18 ... Hard mask pattern 19 ... Pattern formation body 21 ... Transfer substrate 22 ... Transfer material 23 ... Resin pattern with residual film 24 ... Resin pattern 25 ... Replica

Claims (4)

Forming a hard mask layer on the substrate;
Forming a step in the hard mask layer;
Forming a resist layer on the hard mask layer formed with the step;
Forming a uniform pattern on the resist layer;
Performing anisotropic etching on the hard mask layer using the patterned resist layer as an etching mask;
Performing anisotropic etching on the substrate using the patterned hard mask layer as an etching mask, and
A pattern forming method, wherein a region where a pattern of the resist layer is formed is larger than a stepped region formed in the hard mask layer.   In the step of performing anisotropic etching on the hard mask layer, the upper step portion of the hard mask in which the step is formed is left to cover the substrate surface, and the lower step portion of the hard mask in which the step is formed is the substrate surface. The pattern forming method according to claim 1, wherein a part of the pattern is exposed.   The pattern forming method according to claim 1, wherein in the step of forming a step in the hard mask layer, the hard mask layer is left so as to cover a substrate surface.   A pattern forming body produced by using the pattern forming method according to claim 1.

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