JP5866934B2 - Pattern forming method and imprint method - Google Patents

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 (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 hitting the substrate from the electron gun of the drawing machine are scattered and reflected on the surface of the substrate, and some of the electrons jump out of the resist surface, and further on the inner wall of the drawing machine chamber. It is reflected and incident on the resist again. The higher the pattern density, the greater the influence of fogging, and the area affected by the fogging may reach several tens of millimeters. It is known that this resist is slightly sensitized by the energy of re-incident electrons due to fogging, and the pattern affected by the fogging changes in dimensions (see 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 portion where the size has changed due to the influence of fogging and a portion where the size does not change without being affected by the fogging are generated, the dimensions in the resist pattern plane Becomes non-uniform. In particular, a dimensional difference appears remarkably between the pattern outer peripheral portion and the central portion. 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.

  The first reason is that 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 formed. Can't get. For this reason, it is difficult to obtain a desired resist pattern.

  As a second reason, when the resist film is sufficiently thick so that the resist film becomes flat, the aspect ratio of the formed resist pattern increases 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 body 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 resist film on the hard mask layer, patterning the resist film by an electron beam drawing method, and forming a resist pattern And a step of laminating a hard mask material from an upper layer of the resist pattern, and a step of removing the resist pattern and forming a step in a region equal to or smaller than the desired pattern on the hard mask layer. A step of forming a resist layer on the hard mask layer on which the step is formed, a step of forming a uniform pattern on the resist layer by an electron beam drawing method , and the hard mask layer using the patterned resist layer as an etching mask. Performing anisotropic etching on the mask layer; and The layers as an etching mask, and a step of performing anisotropic etching on said substrate, said the hard mask layer material, wherein a high etching selection ratio material to the substrate, the pattern in the resist layer The region to be formed is in 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.

According to a fourth aspect of the present invention, the step of laminating a transfer material on the transfer substrate, the pattern forming body using the pattern forming method according to any one of the first to third aspects, and the transfer substrate are brought close to each other. A step of transferring the pattern of the pattern forming body to the transfer material, and a step of forming an inverted pattern on the transfer substrate using a resist pattern having a pattern formed on the transfer material as a mask. The imprint method is characterized by comprising the above.

  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 The part can form a uniform pattern on the substrate by anisotropically etching the hard mask layer so that the substrate surface is partially exposed. Further, since fogging correction is not required, a process such as setting fogging conditions is not required.

  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. can do. 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.

  In addition, in the process of performing anisotropic etching on the hard mask layer, the hard mask layer to be laminated is a material having an etching selectivity higher than that of the already formed hard mask layer. It is possible to easily form the shape of the hard mask layer where the substrate surface is partially exposed.

It is the general | schematic process figure which showed the principal part in the 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 figure which showed the principal part in the cross section in order to demonstrate the preparation procedure by the imprint method which used 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.

  First, the hard mask layer 12 is formed on the substrate 11 (see FIG. 1A). As a formation method of this hard mask layer 12, according to the material selected for the hard mask layer 12, you may form suitably using a well-known thin film formation method. For example, a sputtering method or the like is used.

  You may select the board | substrate 11 suitably according to a use. 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 selectivity with respect to the selected substrate 11 in the step of performing anisotropic etching on the substrate 11 described later.

  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, a step is formed in the hard mask layer 12 and the process proceeds to a step of forming a hard mask pattern 12 (p1), and a resist material 13 is applied to form a step on the hard mask layer 12 (FIG. 1 ( a) (b) (c) (d)). At this time, the step region formed in the hard mask layer is made equal to a desired pattern region.

  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, and the resist film is patterned to form a resist pattern mask 14. Next, the hard mask material 15 is laminated. The hard mask material 15 may be a material having a high etching selectivity in a process of performing anisotropic etching on the hard mask pattern 12 (p1) described later with respect to the selected hard mask layer 12. As a method for forming the hard mask material 15, a known thin film forming method may be used as appropriate according to the material selected for the hard mask material 15. For example, a sputtering method or the like is used. Next, a step may be formed in the hard mask layer 12 by performing a lift-off process on the resist pattern mask 14.

  Here, since the hard mask pattern 12 (p1) is a material having a high etching selectivity with respect to the substrate 11, the step of the hard mask pattern 12 (p1) corresponding to the pattern to be formed is higher than the desired pattern. Can be small. 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.

  In forming the hard mask pattern 12 (p1), the hard mask layer 12 is left so as to cover the substrate surface. Thereby, in formation of the resist pattern masks 14 and 17, charging (charge-up) of the substrate 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 12 (p1) (see FIG. 1E). The resist material 16 may be appropriately selected according to photolithography, electron beam, or the like for patterning. Further, as a method for forming a coating film of the resist material 16, a known thin film forming technique may be used as appropriate according to 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 (see FIG. 1F). 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, supercritical fluid, or the like. 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 pattern 12 (p1). 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 noticeable compared to the pattern central portion can be arranged outside the step region formed in the hard mask pattern 12 (p1).

  Next, the process proceeds to a step of anisotropically etching the hard mask pattern 12 (p1), and the hard mask pattern 12 (p1) is etched using the resist pattern mask 17 as a mask (see FIG. 1G). Etching may be appropriately performed by a known method. For example, dry etching or wet etching may be performed.

  Here, since the etching selection ratios of the materials formed on the upper and lower portions of the hard mask pattern 12 (p1) are different, the resist pattern mask 17 (m1) formed on the upper portion of the hard mask pattern 12 (p1). The portion etched by the step of leaving the hard mask pattern 12 (p1) so as to cover the surface of the substrate and the portion etched by the resist pattern mask 17 (m2) formed in the lower step are parts of the substrate surface. It is possible to perform anisotropic etching of the hard mask pattern 12 (p1) so that the portion 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 where the hard mask pattern 12 (p1) is formed to form a pattern forming body 18 (FIG. 1 (h) (See (i)). As etching, 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, an imprint method when the pattern forming body 18 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 18 are brought close to each other, and the pattern is transferred to the transfer material 22 to form a resin pattern 23 with a remaining film (see FIG. 2B). At this time, the imprint mold may be subjected to a release treatment. The transfer material 22 may be cured according to the transfer material 22 and the accuracy of the desired pattern. For example, when a thermosetting resin is used as the transfer material 22, curing may be performed by heating. Further, 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, and the imprint mold replica plate 25 in which the unevenness is inverted is manufactured (FIGS. 2C and 2D). )reference).

  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 residual film is a transfer material 22 that exists between the transfer substrate 21 and the imprint mold 18 and refers to a portion where the transferred resin pattern 23 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.

  In the etching step, the etching may be appropriately performed by a known method. For example, dry etching, wet etching, or the like may be performed, and the etching conditions may be adjusted as appropriate depending on 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 10 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 negative electron beam resist.

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

  Next, after depositing 10 nm of the hard mask material 15 using a sputtering apparatus, the resist pattern 15 was removed by a lift-off process to form a hard mask pattern 12 (p1) (see FIGS. 1C and 1D). Further, the step region formed in the hard mask pattern 12 (p1) was made equal to the desired pattern region. At this time, the hard mask material 15 is silicon.

  Next, a resist material 16 was applied to a thickness of 100 nm on the substrate 11 on which the hard mask pattern 12 (p1) having the step was formed (see FIG. 1E).

  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 (f)). 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 12 (p1).

  Next, the hard mask pattern 12 (p1) in which a step is formed by dry etching using an ICP dry etching apparatus with the resist pattern mask 17 as a mask is etched to form a hard mask pattern 12 (p2) in which a desired pattern is formed. (See FIG. 1 (g)).

  At this time, the portion by the resist pattern mask 17 (m1) formed on the upper portion of the hard mask pattern 12 (p1) in which the step is formed is not etched, and the hard mask pattern 12 (p2) so as to cover the surface of the substrate 11. And the hard mask pattern 12 (p2) 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 (m2) formed in the lower stage.

The etching conditions of the chromium film, which is the lower portion of the hard mask pattern 12 (p1) where the step is 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, the substrate 18 was formed by dry etching using an ICP dry etching apparatus using the hard mask pattern 12 (p2) on which a desired pattern was formed as a mask (see FIG. 1H).

  At this time, the etching conditions of the quartz substrate as the substrate were a C4F8 flow rate of 10 sccm, an O2 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 12 (p2) on which a desired pattern was formed was peeled and washed (see FIG. 1 (i)). At this time, wet etching was used for peeling and cleaning the hard mask pattern 12 (p2) on which a desired pattern was formed.

  The pattern forming body 18 can be produced by the above procedure.

(Example 2)
The pattern forming body 18 produced in Example 1 was used as an imprint mold, and an impregnation method for forming a resin pattern 24 having an inverted concavo-convex pattern as shown in FIG. 2 was performed.

  First, a photocurable resin as a transfer material 22 was laminated on the transfer substrate 21 to a thickness of 100 nm, and the pattern forming body 18 was disposed to face (see FIG. 2A).

  At this time, the surface of the pattern forming body 18 that 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 18 are brought into contact with each other, exposure light is irradiated from the pattern forming body 18 side, the transfer material 22 is cured, and the transfer substrate 21 and the pattern forming body 18 are moved away from each other. 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 18 which is a fine imprint mold, and the irradiation amount of UV light as exposure light was 400 mJ / cm 2.

  From the above, it was possible to form the fine resin pattern 23 in which the unevenness of the pattern forming body 18 produced in Example 1 was inverted 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 18 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 implementation stage. Further, 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 requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the effect of the invention can be obtained. In the case where it is possible, this constituent requirement can be extracted as a constituent 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, 12 (p1), 12 (p2) ... Hard mask pattern, 13, 16 ... Resist material, 14, 17 ... Resist pattern mask, 15 ... Hard mask material, 18 ... Pattern formation body , 21 ... transfer substrate, 22 ... transfer material, 23 ... resin pattern with residual film, 24 ... resin pattern, 25 ... replication plate.

Claims (4)

Forming a hard mask layer on the substrate;
Forming a resist film on the hard mask layer, patterning the resist film by an electron beam drawing method, and forming a resist pattern;
Laminating a hard mask material over the resist pattern;
Removing the resist pattern and forming a step in the hard mask layer in a region equal to or smaller than the desired pattern ;
Forming a resist layer on the hard mask layer formed with the step;
Forming a uniform pattern on the resist layer by an electron beam drawing method ;
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
The material to be the hard mask layer is a material having a high etching selectivity with respect to the substrate,
A pattern forming method, wherein a region where a pattern is formed on the resist layer is larger than a stepped region formed on 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.   Laminating a transfer material on a transfer substrate;
  A step of bringing the pattern forming body using the pattern forming method according to claim 1 and the transfer substrate close to each other, and transferring the pattern of the pattern forming body to the transfer material;
  Forming an inverted pattern on the transfer substrate using a resist pattern having a pattern formed on the transfer material as a mask.

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