JP6287046B2 - Reflective mask, reflective mask blank and manufacturing method thereof - Google Patents

Description

  The present invention relates to a reflective mask and a reflective mask blank, and more particularly to a reflective mask used in a semiconductor manufacturing apparatus using EUV lithography that uses extreme ultraviolet (hereinafter referred to as “EUV”) as a light source. The present invention relates to a reflective mask blank and a manufacturing method thereof.

(Description of EUV lithography)
In recent years, with the miniaturization of semiconductor devices, EUV lithography using EUV having a wavelength of around 13.5 nm as a light source has been proposed. Since EUV lithography has a short light source wavelength and very high light absorption, it needs to be performed in a vacuum. In the EUV wavelength region, the refractive index of most substances is slightly smaller than 1. For this reason, the EUV lithography cannot use a transmission type refractive optical system which has been used conventionally, and becomes a reflection optical system. Therefore, a photomask (hereinafter referred to as a mask) as an original plate must be a reflection type mask because a conventional transmission type mask cannot be used.

(Description of EUV mask and blank structure)
In a reflective mask blank that is the basis of such a reflective mask, a multilayer reflective layer showing a high reflectance with respect to the exposure light source wavelength and an absorption layer of the exposure light source wavelength are sequentially formed on a low thermal expansion substrate. Furthermore, a back surface conductive film for an electrostatic chuck in the exposure machine is formed on the back surface of the substrate. There is also an EUV mask having a structure having a multilayer reflection layer and a buffer layer between the absorption layers. When processing from a reflective mask blank to a reflective mask, the absorber layer is partially removed by EB lithography and etching technology, and in the case of a structure having a buffer layer, this is also removed, and the absorber and reflector Is formed. The light image reflected by the reflection type mask thus manufactured is transferred onto the semiconductor substrate via the reflection optical system.

(Explanation of the film thickness and reflectance of the absorption layer of the EUV mask)
In an exposure method using a reflective optical system, irradiation is performed at an incident angle (usually 6 °) tilted by a predetermined angle from the vertical direction with respect to the mask surface. Therefore, when the absorption layer is thick, a shadow of the pattern itself is generated. Therefore, since the reflection intensity in the shadowed portion is smaller than that in the non-shadowed portion, the contrast is lowered, and the transferred pattern is blurred in the edge portion and deviated from the design dimension. This is called shadowing and is one of the fundamental problems of the reflective mask.

  In order to prevent such blurring of the pattern edge portion and deviation from the design dimension, it is effective to reduce the thickness of the absorption layer and reduce the height of the pattern, but when the thickness of the absorption layer becomes small In addition, the light shielding property in the absorbing layer is lowered, the transfer contrast is lowered, and the accuracy of the transfer pattern is lowered. That is, if the absorption layer is too thin, the contrast necessary for maintaining the accuracy of the transfer pattern cannot be obtained. If the film thickness of the absorption layer is too thick or too thin, there is a problem, so it is currently between 50 and 90 nm, and the reflectivity of the EUV light (extreme ultraviolet light) at the absorption layer is 0.5. About 2%.

(Explanation of multiple exposure of adjacent chips)
On the other hand, when a transfer circuit pattern is formed on a semiconductor substrate using a reflective mask, chips having a plurality of circuit patterns are formed on one semiconductor substrate. There may be a region where the outer periphery of the chip overlaps between adjacent chips. This is because the chips are arranged at a high density in order to improve the productivity of increasing the number of chips that can be taken per wafer as much as possible. In this case, this region is exposed (multiple exposure) a plurality of times (up to four times). The chip outer peripheral portion of this transfer pattern is also the outer peripheral portion on the mask, and is usually the absorption layer portion. However, as described above, since the reflectance of EUV light on the absorption layer is about 0.5 to 2%, there is a problem that the outer periphery of the chip is exposed by multiple exposure. For this reason, it has become necessary to provide a region (hereinafter referred to as a light-shielding frame) having a higher light-shielding property of EUV light than a normal absorption layer on the outer periphery of the chip on the mask.

  In order to solve such a problem, by reducing the reflectance of the multilayer reflective layer by forming a groove dug from the absorption layer of the reflective mask to the multilayer reflective layer, the light shielding property with respect to the wavelength of the exposure light source is reduced. A reflective mask provided with a high light-shielding frame has been proposed (see, for example, Patent Document 1).

  However, the EUV light source has a peak of its emission spectrum at 13.5 nm, but also emits light in the near ultraviolet region (wavelength 140 to 400 nm) other than the 13.5 nm band called out-of-band (out of band). It is known to do. This out-of-band 20 transmits through the substrate 1 as shown in FIG. 19 in the proposed light-shielding frame 11, and is formed on the back surface such as chromium nitride (CrN) formed on the surface opposite to the pattern side of the EUV mask. There is a problem in that it is reflected by the film 5, passes through the substrate again, and is emitted to the semiconductor substrate side, and the resist applied to the semiconductor substrate is exposed. In addition, since the pattern region is electrically isolated by forming the light shielding frame, there is a problem of charging up during observation with an electron microscope.

JP 2009-212220 A

  The present invention has been made in view of the above problems, and its object is to reduce reflection of out-of-band light in a mask region corresponding to a boundary region of a chip that is multiple-exposed on a semiconductor substrate, and An object of the present invention is to provide a reflective mask, a reflective mask blank, and a method for manufacturing the same that suppress charge-up that occurs during observation with a microscope.

The present invention has been made in view of such a problem.
A circuit comprising a substrate, a multilayer reflective layer formed on the substrate surface, a protective layer formed on the multilayer reflective layer, and an absorption layer formed on the protective layer, and formed on the absorption layer A light-shielding frame having a low reflectance of EUV light and out-of-band light from which the absorption layer, the protective layer, and the multilayer reflective layer are removed, at least in part outside the pattern region;
An inorganic material containing at least one of Si, Mo, Ta, Cr, Ru, Al, Ti, Zn, Su, Hf, W, Zr, and Cu, or an oxide or nitride thereof on the substrate of the light shielding frame portion or is selected from the oxynitride is obtained by a reflective mask blank, characterized in that the anti-reflection layer having a fourth power / milliohms or more conductivity of 1 × 10 is formed.

The invention of claim 2
The antireflection layer satisfies the following conditional expression (1) in which the light becomes dark due to the interference of the thin film with respect to the wavelength of light (wavelength: 140 to 400 nm) in the vacuum ultraviolet to near ultraviolet region other than the 13.5 nm band that reduces reflection. The reflective type according to claim 1, wherein the reflective type has a function of reflecting the surface in the opposite phase to the out-of-band light reflected from the substrate surface by selecting and adjusting the refractive index and film thickness of the material. It is a mask blank.
2nd cos θ = mλ (1)
n: Refractive index d: Film thickness θ: Incident angle λ: Wavelength (m = 0, 1, 2,...)

The invention of claim 3
A method of manufacturing a reflective mask blank according to claim 1 or 2 ,
The method for producing the antireflection layer is a method for producing a reflective mask blank, which is formed by any one of sputtering, vapor deposition (PVD), ion plating, and CVD.

The invention of claim 4
A method of manufacturing a reflective mask blank according to claim 1 or 2 ,
The method for producing the antireflection layer is a method for producing a reflective mask blank, which is formed on a substrate before forming a multilayer reflective layer.

The invention of claim 5
A method for producing a reflective mask blank according to claim 2 ,
The method for producing the antireflection layer is a method for producing a reflective mask blank, wherein the multilayer reflective layer is partially removed and then formed on the exposed substrate.

The invention of claim 6
The reflective mask blank according to claim 1 or 2 , wherein the absorbing layer is patterned to provide a reflective mask.

  Anti-reflective surface reflection in reverse phase with respect to out-of-band light reflected from backside conductive film and substrate surface in light-shielding frame formed in mask area corresponding to boundary area of chip subjected to multiple exposure on semiconductor substrate By having the layer, it is possible to provide a reflective mask with reduced reflection of out-of-band light.

  In addition, in the conventional mask with a light shielding band, the pattern region is electrically floated by the formation of the light shielding band, so at the time of observation with an electron microscope, at the time of inspection with an electron beam mask inspection apparatus, at the time of exposure with an EUV exposure machine, Although there is a problem that the pattern region is charged up, the antireflection layer of the present invention has conductivity, so that the charge-up of the pattern region caused by the light shielding band can be suppressed.

  By using the reflective mask having such a configuration, the pattern dimensional accuracy of the semiconductor can be improved, and the manufacturing yield of the semiconductor and the like can be improved.

It is a schematic sectional drawing of the structure of the reflective mask of this invention (a), (b). It is the schematic sectional drawing (c) of the structure of the reflective mask blank of this invention, and the schematic plan view (d) of the reflective mask of this invention. It is the side schematic diagram of the mask which reduces the out-of-band light from a board | substrate by the antireflection layer of this invention. It is the side schematic diagram of the mask which reduces the out-of-band light from a back surface conductive film by the antireflection layer of this invention. It is the side schematic diagram of the mask which reduces the out-of-band light from a board | substrate with the antireflection layer of only the light-shielding frame part of this invention. FIG. 4 is a schematic side view of a mask for reducing out-of-band light from a back conductive film by using an antireflection layer having only a light shielding frame portion according to the present invention. It is a schematic sectional drawing which shows a part of preparation process 1 (pattern formation) of the reflective mask of the Example of this invention. It is a schematic sectional drawing which shows the other part of the manufacturing process 1 (pattern formation) of the reflective mask of the Example of this invention. It is a schematic plan view which shows a part of manufacturing process 1 (shading frame formation) of the reflective mask of the Example of this invention. It is a schematic plan view which shows the other part of the manufacturing process 1 (shading frame formation) of the reflective mask of the Example of this invention. It is a schematic sectional drawing which shows a part of manufacturing process 2 (pattern formation) of the reflective mask of the Example of this invention. It is a schematic sectional drawing which shows the other part of the manufacturing process 2 (pattern formation) of the reflective mask of the Example of this invention. It is a schematic plan view which shows a part of manufacturing process 2 (shading frame formation) of the reflective mask of the Example of this invention. It is a schematic plan view which shows the other part of the manufacturing process 2 (shading frame formation) of the reflective mask of the Example of this invention. It is a schematic plan view which shows the other part of the production process 2 (shading frame formation) of the reflective mask of the Example of this invention. It is a schematic plan view which shows the evaluation pattern of the Example of this invention. It is the reflectance result of the out-of-band light of (a) the conventional reflective mask of the Example of this invention, and (b) the reflective mask 701 which has the light-shielding frame and antireflection layer of this invention. (C) It is the reflectance result of the out-of-band light of the reflective mask 902 which has a light-shielding frame and an antireflection layer of the Example of this invention. It is the schematic of reflection of the out-of-band light in a conventional mask.

(Configuration of Reflective Mask and Reflective Mask Blank of the Present Invention)
Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

  First, the configuration of an example of the reflective mask of the present invention will be described. 1A and 1B are schematic sectional views of the structure of the reflective mask of the present invention, and FIG. 2C is a schematic sectional view of the structure of the reflective mask blank of the present invention. d) is a schematic plan view of FIGS. 1 (a) and 1 (b) from above. That is, 101 and 102 are examples of the configuration of the reflective mask of the present invention.

In the reflective mask 101 shown in FIG. 1A, an antireflection layer 12, a multilayer reflective layer 2, a protective layer 3, an absorption layer 4, a pattern region 10, and a light shielding frame 11 are sequentially formed on the surface of the substrate 1. . The reflective mask 102 shown in FIG. 1B has a multilayer reflective layer 2, a protective layer 3, an absorption layer 4, a pattern region 10, and a light shielding frame 11 formed in order on the surface of the substrate 1, and only on the light shielding frame 11. An antireflection layer 12 is formed. In the reflective mask blank 103 shown in FIG. 2C, the antireflection layer 12, the multilayer reflective layer 2, the protective layer 3, and the absorption layer 4 are sequentially formed on the surface of the substrate 1. The back surface conductive film 5 is formed on the back surface of the substrate. There may be a buffer layer between the protective layer 3 and the absorbing layer 4. The buffer layer is a layer provided so as not to damage the underlying protective layer 3 when the mask pattern of the absorption film 4 is corrected.

  The reflective masks 101 and 102 of the present invention are antiphase with respect to the out-of-band light reflected from the interface between the back surface conductive film 5 and the substrate 1 in the light shielding frame region and the surface of the substrate 1 by the antireflection layer 12. And has a region that reflects the surface.

The antireflection layer 12 of the present invention reflects out-of-band light reflected from the interface between the back conductive film 5 and the substrate 1 and the surface of the substrate 1 with an antiphase, so the material and film thickness of the antireflection layer are adjusted. Has been. Specifically, the refractive index and film thickness of the material may be selected and adjusted so as to satisfy the conditional expression (1) in which light is darkened by thin film interference.
2nd cos θ = mλ (1)
n: Refractive index d: Film thickness θ: Incident angle λ: Wavelength (m = 0, 1, 2,...)
FIG. 3 is a schematic side view of a mask for reducing the out-of-band light 20 from the substrate 1 by the antireflection layer 12 according to the present invention (FIG. 3A). When the out-of-band light 20 enters the antireflection layer 12, the interface reflected light 22 reflected by the substrate 1 has an opposite phase to the surface reflected light 21 of the antireflection layer 12, so that the two lights cancel each other out due to interference. Then, the reflection of the out-of-band light 20 is reduced (FIG. 3B). In order to make the interface reflected light 22 have the opposite phase to the surface reflected light 21, it can be achieved by adjusting the material and film thickness of the antireflection layer 12.

  FIG. 4 is a schematic side view of a mask for reducing the out-of-band light 20 from the back surface conductive film 5 by the antireflection layer 12 according to the present invention (FIG. 4A). When the out-of-band light 20 is incident on the antireflection layer 12, the interface reflected light 23 reflected by the back surface conductive film 5 is out of phase with the surface reflected light 21 by the antireflection layer 12. Canceling each other, the reflection of the out-of-band light 20 is reduced (FIG. 4B). In order to make the interface reflected light 23 have the opposite phase to the surface reflected light 21, it can be achieved by adjusting the material and film thickness of the antireflection layer 12.

  FIG. 5 is a schematic side view of a mask for reducing the out-of-band light 20 from the substrate 1 by the antireflection layer 12 formed only on the light shielding frame portion according to the present invention (FIG. 5A). When the out-of-band light 20 is incident on the antireflection layer 12, the interface reflected light 22 reflected by the substrate 1 is out of phase with the surface reflected light 21 by the antireflection layer 12, so that the two lights cancel out due to interference. Then, the reflection of the out-of-band light 20 is reduced (FIG. 5B). In order to make the interface reflected light 22 have the opposite phase to the surface reflected light 21, it can be achieved by adjusting the material and film thickness of the antireflection layer 12.

  FIG. 6 is a schematic side view of a mask for reducing the out-of-band light 20 from the back surface conductive film 5 by the antireflection layer 12 formed only in the light shielding frame portion according to the present invention (FIG. 6A). When the out-of-band light 20 is incident on the antireflection layer 12, the interface reflected light 23 reflected by the back surface conductive film 5 is out of phase with the surface reflected light 21 by the antireflection layer 12. Canceling each other, the reflection of the out-of-band light 20 is reduced (FIG. 6B). In order to make the interface reflected light 23 have the opposite phase to the surface reflected light 21, it can be achieved by adjusting the material and film thickness of the antireflection layer 12.

  The antireflection layer 12 according to the present invention is not limited in material as long as it has a refractive index and a film thickness that satisfy the above-described conditional expression (1). However, the antireflection layer 12 needs to be able to withstand vacuum and EUV light, and thus is chemically stable. Inorganic material. Specifically, the material includes Si, Mo, Ta, Cr, Ru, Al, Ti, Zn, Su, Hf, W, Zr, and Cu.

Further, the antireflection layer 12 according to the present invention may be an oxide, nitride, or oxynitride of the above materials. This is because it is desirable to increase the amplitude to some extent in order to enhance the interference effect of the light having the opposite phase, and therefore, it is an effective method for reducing the extinction coefficient.

  The antireflection layer 12 of the present invention has an electrical conductivity of 1 × 10 4 / mΩ or more. This is because the pattern area is electrically floating due to the formation of a light-shielding band, and the pattern area is charged up during observation / measurement with an electron beam, inspection with an electron beam mask inspection device, and exposure with an EUV exposure machine. This is to solve the problem.

  The low-reflective antireflection layer 12 of the present invention is preferably formed on the substrate before the multilayer reflective layer is formed, since the number of steps is small, but it is exposed after the multilayer reflective layer is partially removed. You may form on a board | substrate.

(Details of the configuration of the reflective mask of the present invention: multilayer reflective layer, protective layer, buffer layer)
The multilayer reflective layer 2 in FIG. 1A is designed to achieve a reflectance of about 60% with respect to EUV light, and is a laminated film in which 40-50 pairs of Mo and Si are alternately laminated. The upper protective layer 3 is made of ruthenium (Ru) having a thickness of 2 to 3 nm or silicon (Si) having a thickness of about 10 nm. The layer adjacent to the Ru layer is a Si layer. The reason why Mo and Si are used is that the absorption (extinction coefficient) with respect to EUV light is small and the refractive index difference between Mo and Si EUV light is large. This is because it can be high. When the protective layer 3 is Ru, it plays a role as a stopper in processing of the absorption layer 4 and a protective layer against chemicals during mask cleaning. When the protective layer 3 is Si, there may be a buffer layer between the absorption layer 4 and the protective layer 3. The buffer layer is provided to protect the Si layer, which is the uppermost layer of the multilayer reflective layer 2 adjacent to the bottom of the buffer layer, during etching or pattern correction of the absorption layer 4, and is made of chromium (Cr) or nitrogen compound ( CrN).

(Details of the configuration of the reflective mask of the present invention: absorption layer)
The absorption layer 4 in FIG. 1A is composed of a nitrogen compound (TaN) of tantalum (Ta) having a high absorption rate with respect to EUV. As other materials, tantalum boron nitride (TaBN), tantalum silicon (TaSi), tantalum (Ta), and oxides thereof (TaBON, TaSiO, TaO) may be used.

  The absorption layer 4 in FIG. 1A may be an absorption layer having a two-layer structure in which an upper layer is provided with a low reflection layer having an antireflection function with respect to ultraviolet light having a wavelength of 190 to 260 nm. The low reflection layer is for increasing the contrast and improving the inspection property with respect to the inspection wavelength of the mask defect inspection machine.

(Details of Configuration of Reflective Mask of the Present Invention: Back Conductive Film)
Although the back surface conductive film 5 in FIG. 1A is generally made of CrN, it only needs to be conductive, so any material made of a metal material may be used. In FIG. 1A, the back surface conductive film 5 is described. However, a mask blank and a mask without the back surface conductive film 5 may be used.

(Method for producing the reflective mask of the present invention)
The reflective mask manufacturing method 1 of the present invention will be described. First, a resist 9 is applied to the reflective mask blank 103 having the antireflection layer shown in FIG. 2C (FIG. 7A). Next, a pattern is formed in the main region shown in FIG. 7B by photolithography or electron beam lithography. According to the pattern, the absorption layer 4 is processed by dry etching using a fluorine-based gas and / or a chlorine-based gas, or by wet etching using an alkaline solution or an acidic solution (FIG. 8C). Subsequently, when the resist 9 is stripped and cleaned, a reflective mask 602 having a pattern formed in the main region is formed (FIG. 8D).

  A method 1 for forming a light shielding frame of a reflective mask according to the present invention will be described. First, a resist 71 is applied to a reflective mask 602 having an antireflection layer (FIG. 9A). Next, a resist pattern in which only the light shielding frame portion is opened is formed by photolithography or electron beam lithography (FIG. 9B). Next, the absorption film 4 at the opening portion of the resist pattern is removed by dry etching using fluorine-based or chlorine-based gas (or both) (FIG. 10C). Next, the protective layer 3 and the multilayer reflective layer 2 are formed by dry etching using a fluorine-based gas and / or a chlorine-based gas, or wet etching using an alkaline solution or an acidic solution. Is penetrated and removed (FIG. 10D). Subsequently, when the resist 71 is stripped and cleaned, a pattern is formed in the main region, and a reflective mask 701 having a light shielding frame and an antireflection layer is formed (FIG. 10E).

  The reflective mask manufacturing method 2 of the present invention will be described. 11A shows a structure in which a multilayer reflective layer 2, a protective layer 3, an absorption layer 4, and a resist 9 are sequentially formed on the surface of the substrate 1, and a back surface conductive film 5 is formed on the back surface of the substrate 1. FIG. ing. Next, a pattern is formed in the main region shown in FIG. 11B by photolithography or electron beam lithography. According to the pattern, the absorption layer 4 is processed by dry etching using a fluorine-based gas and / or a chlorine-based gas, or by wet etching using an alkaline solution or an acidic solution (FIG. 12C). Subsequently, when the resist 9 is stripped and cleaned, a reflective mask 802 having a pattern formed in the main region is formed (FIG. 12D).

  A method 2 for forming the light shielding frame of the reflective mask of the present invention will be described. First, a resist 71 is applied to the reflective mask 802 (FIG. 13A). Next, a resist pattern in which only the light shielding frame is opened is formed by photolithography or electron beam lithography (FIG. 13B). Next, the absorption film 4 at the opening portion of the resist pattern is removed by dry etching using fluorine-based or chlorine-based gas (or both) (FIG. 13C). Next, the protective layer 3 and the multilayer reflective layer 2 are formed by dry etching using a fluorine-based gas and / or a chlorine-based gas, or wet etching using an alkaline solution or an acidic solution. Is penetrated and removed (FIG. 14D). Subsequently, when the resist 71 is stripped and cleaned, a reflective mask 901 with a light shielding frame in which a pattern is formed in the main region is formed (FIG. 14E). Further, a resist 91 is applied to the reflective mask 901 (FIG. 14F). By photolithography or electron beam lithography, a resist pattern in which only the light shielding frame portion is opened is formed (FIG. 15G). The antireflection layer 12 is formed by any one of sputtering, vapor deposition (PVD), ion plating, and CVD (FIG. 15 (h)). Finally, when the resist 91 is stripped and cleaned, a pattern is formed in the main region, and a reflective mask 902 having a light shielding frame and an antireflection layer is formed (FIG. 15 (i)).

When the multi-layer reflective layer 2 is penetrated and removed by dry etching, the fluorine-based gas and / or the chlorine-based gas is used for both Mo and Si, which are the materials of the multi-layer reflective layer. It is for having. The fluorine-based gas used at this time is CF ₄ , C ₂ F ₆ , C ₄ F ₈ , C ₅ F ₈ , CHF ₃ , SF ₆ , ClF ₃ , etc., and chlorine gases include Cl ₂ and HCl. .

  An etching solution for penetrating / removing the multilayer reflective layer 2 by wet etching needs to be suitable for etching Mo and Si that are materials of the multilayer reflective layer 2. For example, as the alkaline solution, TMAH (tetramethylammonium hydroxide), KOH (potassium hydroxide), and EDP (ethylenediamine pyrocatechol) are suitable. As the acidic solution, a mixed solution of nitric acid and phosphoric acid is suitable, but hydrofluoric acid, sulfuric acid, and acetic acid may be added thereto.

The antireflection layer is at least Si, Mo, Ta, Cr, Ru, Al, Ti, Zn, Su, H
It is an inorganic material that includes f, W, Zr, and Cu and has a conductivity of 1 × 10 4 to the power / mΩ or higher.
As described above, in an EUV mask having a multilayer reflective layer removal type light-shielding region, the reflection of out-of-band light is reduced, and when observing with an electron microscope or inspection with an electron beam mask inspection apparatus, exposure with an EUV exposure machine It is possible to obtain a reflective mask that suppresses charge-up that sometimes occurs.

  Examples of the method for manufacturing a reflective mask according to the present invention will be described below. In the example, a reflective mask blank 601 having the antireflection layer 12 shown in FIG. 2C was prepared. This blank is designed so that the antireflection layer 12 made of MoSiON containing Mo, Si, O, and N on the substrate 1 has a reflectance of about 64% with respect to EUV light having a wavelength of 13.5 nm. Further, a 40-pair multilayer reflective layer 2 of Mo and Si, a 2.5 nm thick Ru protective layer 3 thereon, and a 70 nm thick TaSi absorbing layer 4 are sequentially formed thereon.

  The film thickness d of the antireflection layer is obtained by using conditional expression (2) obtained by modifying conditional expression (1) in which the interference light from the thin film becomes dark. The refractive index n at a wavelength of 300 nm which is the out-of-band light of the antireflection layer 12 made of MoSiON of the present invention is 2.26, the incident angle is 6 °, and the integer m is 1. When the above value is substituted into the conditional expression (2), d is about 66.7 nm. Therefore, the antireflection layer was formed by sputtering so that the film thickness was 67 nm.

本ブランクに対し、ポジ型化学増幅レジスト９（ＦＥＰ１７１：富士フイルムエレクトロニクスマテリアルズ）を３００ｎｍの膜厚で塗布し（図７（ａ））、電子線描画機（ＪＢＸ９０００：日本電子）によって描画後、１１０℃、１０分のＰＥＢおよびスプレー現像（ＳＦＧ３０００：シグマメルテック）により、図７（ｂ）に示すメイン領域にレジストパターンを形成した。

Positive chemical amplification resist 9 (FEP171: Fuji Film Electronics Materials) was applied to the blank with a film thickness of 300 nm (FIG. 7A), and after drawing by an electron beam drawing machine (JBX9000: JEOL), A resist pattern was formed in the main region shown in FIG. 7B by PEB at 110 ° C. for 10 minutes and spray development (SFG3000: Sigma Meltech).

  Next, the reflective layer having the evaluation pattern shown in FIG. 8D is obtained by etching the absorption layer 4 with CF4 plasma and Cl2 plasma using a dry etching apparatus (FIG. 8C) and cleaning the resist by peeling. A mask 602 was produced. The evaluation pattern was arranged in the center of the mask using a 200 nm 1: 1 line and space pattern shown in FIG. The size of the pattern region was 10 cm × 10 cm.

  Next, a process of forming a light shielding frame was performed on the pattern region 10 of the reflective mask 602 having the above-described evaluation pattern. By applying an i-line resist 71 to a reflective mask 602 (FIG. 8D) with a film thickness of 500 nm (FIG. 9A), drawing and developing with an i-line drawing machine (ALTA) there, A resist pattern in which a region that later becomes a light shielding frame was drawn was formed (FIG. 9B). At this time, the opening width of the resist pattern was 5 mm, and the resist pattern was arranged at a distance of 3 μm (micrometer) from the main pattern region of 10 cm × 10 cm in the center of the mask.

  Next, using a dry etching apparatus, CHF3 plasma (pressure in the dry etching apparatus 50 mTorr, ICP (inductively coupled plasma) power 500 W, RIE (reactive ion etching) power 200 W, CHF3: flow rate 20 sccm, processing time 6 minutes, Then, the absorption layer 4, protective layer 3 and multilayer reflective layer 2 in the opening of the resist are penetrated and removed by vertical dry etching (FIGS. 10C and 10D). ) Was obtained.

Finally, the resist was removed and washed with a sulfuric acid-based stripping solution and ammonia hydrogen peroxide solution, and the remaining resist was removed by dry etching to form a reflective mask 701 (FIG. 10E).

  Next, a reflective mask having a conventional light shielding frame, a reflective mask 701 having a light shielding frame and an antireflection layer according to the present invention, and a reflective mask 902 having a light shielding frame and an antireflection layer according to the present invention are prepared. The reflectance in the area was measured. As a result, as shown in FIGS. 17 and 18, the reflectance of the reflective mask 701 having the light shielding frame and the antireflection layer of FIG. 17B is as shown in FIG. It was confirmed that the reflectance was reduced by about 40% with out-of-band light having a wavelength of 200 nm to 400 nm as compared with the reflectance of the mold mask. Further, in FIG. 18C, the reflective mask 902 having the light shielding frame and the antireflection layer of the present invention also has an out wavelength of 200 nm to 400 nm as compared with the reflectance of (a) the conventional reflective mask having the light shielding frame. It was confirmed that the reflectance was reduced by about 40% with the out-of-band light.

  In addition, a reflective mask having a conventional light shielding frame, a reflective mask 701 having a light shielding frame and an antireflection layer according to the present invention, and a reflective mask 902 having a light shielding frame and an antireflection layer according to the present invention are 200 nm. When the 1: 1 line & space pattern was observed with an electron microscope, only the reflective mask having the conventional light-shielding frame became unclear due to charge-up.

  As described above, it was possible to produce a reflective mask that reduces the reflection of out-of-band light and suppresses the charge-up that occurs during observation with an electron microscope.

The present invention is useful for a reflective mask or the like.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Multilayer reflective layer 3 Protective layer 4 Absorbing layer 5 Back surface conductive film 9 Resist 10 Pattern region 11 Shading frame 12 Antireflection layer 20 Out-of-band light 21 Surface reflected light 22 Interface reflected light from substrate 23 Back surface conductive film Interface reflection light 71 Resist 91 Resist 101 Reflective mask 102 having antireflection layer of the present invention Reflective mask 103 having antireflection layer only in the light shielding frame of the present invention Reflective mask blank 601 having antireflection layer of the present invention Reflection Reflective mask blank 602 having an antireflection layer Reflective mask 701 having an antireflection layer of the present invention Reflective mask 801 having a light shielding frame and an antireflection layer Reflective mask blank 802 Reflective mask 901 Reflective mask 902 having a light shielding frame Reflective mask having a light shielding frame and an antireflection layer

Claims (6)

A circuit comprising a substrate, a multilayer reflective layer formed on the substrate surface, a protective layer formed on the multilayer reflective layer, and an absorption layer formed on the protective layer, and formed on the absorption layer A light-shielding frame having a low reflectance of EUV light and out-of-band light from which the absorption layer, the protective layer, and the multilayer reflective layer are removed, at least in part outside the pattern region;
An inorganic material containing at least one of Si, Mo, Ta, Cr, Ru, Al, Ti, Zn, Su, Hf, W, Zr, and Cu, or an oxide or nitride thereof on the substrate of the light shielding frame portion or is selected from the oxynitride, the reflective mask blank, characterized in that the anti-reflection layer is formed with a fourth power / milliohms or more conductivity of 1 × 10,. The antireflection layer satisfies the following conditional expression (1) in which the light becomes dark due to the interference of the thin film with respect to the wavelength of light (wavelength: 140 to 400 nm) in the vacuum ultraviolet to near ultraviolet region other than the 13.5 nm band that reduces reflection. The reflective type according to claim 1, wherein the reflective type has a function of reflecting the surface in the opposite phase to the out-of-band light reflected from the substrate surface by selecting and adjusting the refractive index and film thickness of the material. Mask blank.
2nd cos θ = mλ (1)
n: Refractive index d: Film thickness θ: Incident angle λ: Wavelength (m = 0, 1, 2,...) A method of manufacturing a reflective mask blank according to claim 1 or 2 ,
The method for producing the antireflection layer is formed by any one of sputtering, vapor deposition (PVD), ion plating, and CVD. A method of manufacturing a reflective mask blank according to claim 1 or 2 ,
The method for producing an antireflection layer is formed on a substrate before forming a multilayer reflective layer. A method of manufacturing a reflective mask blank according to claim 1 or 2 ,
The method of manufacturing the reflection type mask blank is characterized in that the antireflection layer is formed on the exposed substrate after partially removing the multilayer reflection layer. The reflective mask blank according to claim 1 or 2 , wherein the absorption layer is patterned.

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