JP2014183075A - Reflective mask, and method of manufacturing the same - Google Patents

Abstract

To provide a reflective mask with good positional accuracy quality in the vicinity of a light shielding region and a method for manufacturing the same.
A reflective mask comprising a multilayer reflective layer formed on a substrate surface and an absorption layer formed on the multilayer reflective layer and having a circuit pattern. A light-shielding region from which the absorption layer and the multilayer reflective layer are removed is formed outside the circuit pattern region, and stress reduction processing is performed on the multilayer reflective layer in the vicinity of the light-shielding region formed in the multilayer reflective layer. It is characterized by having the area | region made.
[Selection] Figure 1

Description

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

  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 materials is slightly smaller than 1. Therefore, in the EUV lithography, a conventionally used transmission type refractive optical system can be used. First, it 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.

  A reflective mask blank that is the basis of such a reflective mask has, on a low thermal expansion substrate, a multilayer reflective layer that exhibits a high reflectance with respect to the exposure light source wavelength, and an absorption layer that absorbs the exposure light source wavelength. The back surface conductive film for the electrostatic chuck in the exposure machine is further formed on the back surface of the substrate. There is also an EUV mask having a structure having a buffer layer between a multilayer reflective layer and an absorption layer.

  When processing from a reflective mask blank to a reflective mask, the absorption layer is partially removed by EB lithography and etching technology. In the case of a structure having a buffer layer, the buffer layer is also removed in the same manner. A circuit pattern including a reflection portion is formed. The light image reflected by the reflection type mask thus manufactured is transferred onto the semiconductor substrate via the reflection optical system.

  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 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 is reduced Since 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. Also, since the thickness of the absorption layer is too thick or too thin, it is currently in the range of 50 to 90 nm, and the reflectance of the EUV light (extreme ultraviolet light) at the absorption layer is 0. About 5 to 2%.

  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, the overlapping region is exposed (multiple exposure) a plurality of times (up to four times). The outer peripheral portion of the chip in this transfer pattern is also the outer peripheral portion on the mask, and is usually located at the portion that hits the absorbing layer. 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 region) 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 region has been proposed (see, for example, Patent Document 1).

  On the other hand, the multilayer reflective layer used for the EUV mask is formed by alternately depositing Si (silicon) and Mo (molybdenum) with thicknesses of about 4.2 nm and about 2.8 nm, respectively, for a total of 40 to 50 pairs. (= About 80 to 100 layers). Si and Mo are used to increase the reflectivity at the interface between Si and Mo because the absorption (extinction coefficient) with respect to EUV light is small and the refractive index difference between EUV light between Si and Mo is large. . EUV light that is transmitted without being reflected at the first interface is reflected at the next interface, but EUV light that is transmitted without being reflected there is also reflected at the next interface, and so on for 40 times (in the case of 40 pairs). There is a chance to reflect. The EUV light reflected at each interface has the same phase, and the sum is the EUV reflectivity from the multilayer reflective layer. For EUV blanks (EUV mask substrates) sold by blank manufacturers, it is approximately 62 to About 65%.

  The EUV mask reflectivity directly affects the throughput (production capacity) of the semiconductor chip manufacturing, so it is desirable that the EUV mask reflectivity be as high as possible. However, currently known materials and combinations thereof are the above-described multilayer reflection of Si and Mo. The layer is considered the best. The essential ability to produce reflectivity is the interface between Si and Mo, and it is important that the interface is formed exactly. For this reason, a method is employed in which Si and Mo are alternately formed (mainly sputtering) without breaking the vacuum in the same vacuum chamber.

  In addition, since the material after vacuum film formation is unstable and has a strong internal stress, the substrate after film formation is subjected to heat treatment (annealing) for material stabilization, densification, stress adjustment, etc. However, in an EUV blank to be used as an EUV mask later, heat treatment immediately after film formation cannot be positively performed because mixing of Si and Mo materials occurs. Mixing causes the interface between Si and Mo to be lost, leading to a reduction in EUV light reflectivity.

  Therefore, in the present EUV blank, a strong compressive stress remains in the multilayer reflective layer, which causes a warpage of about 500 to 1000 nm on the entire substrate.

JP 2009-212220 A

When a light-shielding region in which the multilayer reflective layer is dug is formed for such a multilayer reflective layer having a strong compressive stress (Patent Document 1), the partial release of the compressive stress of the multilayer reflective layer particularly causes the light-shielding region. The problem is that the position changes suddenly. In general, the formation of the light shielding region in which the multilayer reflective layer is dug needs to be performed by light or electron beam lithography and etching after the formation of the main pattern in the image field. This is to prevent defects from occurring in the most important main pattern. The main pattern formation needs to be in the state with the highest cleanliness of the blank, that is, if a main pattern is formed later on a blank that has been subjected to extra processing such as a step due to the formation of a light shielding region, a defect is generated. This is because the risk becomes much higher.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a reflective mask having a light shielding region in which the positional accuracy in the vicinity of the light shielding region is less deteriorated and a method for manufacturing the same.

  The invention of claim 1 of the present invention comprises a multilayer reflective layer formed on the substrate surface, and an absorption layer formed on the multilayer reflective layer and having a circuit pattern, outside the region of the circuit pattern. A reflection type in which a light shielding region from which the absorption layer and the multilayer reflection layer are removed is formed, and a stress reduction region in which internal stress is reduced is formed in the multilayer reflection layer in the vicinity of the light shielding region. It is a mask.

  According to a second aspect of the present invention, in the stress reduction region in the vicinity of the light shielding region, the internal stress of the multilayer reflective layer is 100 MPa or less at a distance of at least 15 μm from the edge of the light shielding region. The reflective mask according to Item 1 is used.

  According to a third aspect of the present invention, there is provided a method of manufacturing a reflective mask according to the first or second aspect, wherein after the absorption layer is selectively removed, the multilayer reflective layer is selectively dry-etched or A reflective mask characterized in that a light shielding region formed in the multilayer reflective layer is formed by wet etching, and then a stress reduction region is formed by locally modifying only the vicinity of the light shielding region. This is a manufacturing method.

  According to a fourth aspect of the present invention, in the modification processing method for forming the stress reduction region, only the vicinity of the light shielding region is irradiated with laser light locally. This is a method for manufacturing a mold mask.

  According to a fifth aspect of the present invention, in the modification processing method for forming the stress reduction region, only the vicinity of the light shielding region is irradiated with a flash lamp locally. This is a method for manufacturing a mold mask.

  According to a sixth aspect of the present invention, in the modification processing method for forming the stress reduction region, only the vicinity of the light shielding region is irradiated with an ion beam or an electron beam locally. This is a manufacturing method of the reflective mask described.

  The invention according to claim 7 of the present invention is characterized in that the dry etching is performed using a gas containing fluorine or chlorine as an etching gas. It is a thing.

According to an eighth aspect of the present invention, the etching gas containing fluorine is selected from the group consisting of CF ₄ , C ₂ F ₆ , C ₄ F ₈ , C ₅ F ₈ , CHF ₃ , SF ₆ , and ClF _3. The method of manufacturing a reflective mask according to claim 7, wherein the gas contains at least one kind.

  The reflection type according to claim 7 or 8, wherein the etching gas containing chlorine is a gas containing at least one selected from the group consisting of Cl and HCl. This is a method for manufacturing a mask.

According to a tenth aspect of the present invention, the wet etching is performed using an etching solution containing at least one selected from the group consisting of nitric acid, phosphoric acid, hydrofluoric acid, sulfuric acid, and acetic acid. It is set as the manufacturing method of the reflective mask in any one of claim | item 3 -6.

  According to an eleventh aspect of the present invention, the laser light is performed using a laser including at least one selected from the group consisting of a femtosecond laser, a YAG laser, and a CO2 laser. The reflective mask manufacturing method is used.

  According to the present invention, in the reflective mask in which the light shielding region is formed by removing the absorption layer and the multilayer reflective layer outside the circuit pattern region, the position variation in the vicinity of the edge of the light shielding region can be reduced. A reflective mask with a light-shielding region is provided, thereby producing an effect that a highly accurate transfer pattern can be formed.

(A) The schematic sectional drawing of the structure of the reflective mask of this invention, (b) A schematic plan view. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view illustrating a manufacturing process (up to pattern formation) of a reflective mask according to Example 1 of the present invention. 1 is a schematic plan view showing a reflective mask (up to pattern formation) of Example 1 of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view illustrating a manufacturing process (formation of a light shielding region and a stress reduction region) of a reflective mask according to Example 1 of the present invention. Schematic which shows the reflective mask of Example 1 of this invention. The position accuracy result of the reflective mask of Example 1 of this invention. The transmission electron microscope photograph before and behind formation of the stress reduction area | region of the reflective mask of Example 1 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of the reflective mask according to the present embodiment)
First, the configuration of the reflective mask according to this embodiment will be described. FIG. 1A is a schematic sectional view of the structure of the reflective mask 101 according to the present embodiment, and FIG. 1B is a schematic plan view of the reflective mask 101 as viewed from above.

  In the reflective mask 101 shown in FIGS. 1A and 1B, a multilayer reflective layer 2, a protective layer 3, and an absorption layer 4 are sequentially formed on the surface of the substrate 1, and a conductive film 5 is formed on the back surface of the substrate. It has a structure. A buffer layer may be interposed between the protective layer 3 and the absorption 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 layer 4 is corrected (such as ion beam, mechanical grinding with a fine probe). Further, the protective film 3 needs to be made of a material having resistance to washing against acid and alkali, and generally Ru (ruthenium) or Si (silicon) is used.

  The reflective mask 101 according to the present embodiment includes a pattern region 10 in which an absorption layer 4 is processed and a pattern is formed, and an absorption layer 4, a protective layer 3, a multilayer reflection layer 2, and a buffer layer on the outer periphery thereof. In some cases, the buffer layer has a frame-shaped light-shielding region (light-shielding groove) 11 removed, and the multilayer reflective layers on both sides of the light-shielded region are stress-reduced regions 12 in which the internal stress of the multilayer reflective layer is reduced. Is formed.

  The stress reduction region is at least a distance of at least 15 μm from the edge of the light shielding region. The reason for this is that when a multi-layer reflective layer removal type light shielding region is formed, the multilayer reflective layer near the light shielding region is deformed (extends in the direction of the light shielding region) due to partial release of internal stress (strong compressive stress) of the multilayer reflective layer. This is because the deformation range is about 15 μm from the edge of the light shielding region. Naturally, since the internal stress of the multilayer reflective layer originally possessed by the EUV blank varies, when the internal stress is large, the deformation range due to the formation of the light-shielding region is large, so the stress reduction region may be larger than 15 μm. .

  By reducing the internal stress of the multilayer reflective layer in the stress reduction region to 100 MPa or less, the deformation amount in the vicinity of the light shielding region becomes a level with no problem. Generally, the internal stress of the multilayer reflective layer of EUV blanks sold by current EUV blank manufacturers is said to be 200 to 500 MPa. By making the stress reduction region of the present invention 100 MPa or less, the multilayer reflective layer The amount of deformation (corresponding to a change in the position of the mask pattern) can be reduced to at least half.

(Multilayer reflective layer, protective layer, buffer layer)
The multilayer reflective layer 2 of the reflective mask shown in FIG. 1A is designed to achieve a reflectivity of about 60% with respect to EUV light, and includes a molybdenum (Mo) layer and a silicon (Si) layer. It is a laminated film in which 40 to 50 pairs are alternately laminated. The protective layer 3 formed on the multilayer reflective layer 2 is a ruthenium (Ru) layer having a thickness of 2 to 3 nm or a silicon (Si) layer having a thickness of about 10 nm. In this case, the uppermost layer of the multilayer reflective layer 2 adjacent below the protective layer 3 made of Ru is a Si layer.

  Mo and Si have low absorption (extinction coefficient) for EUV light and a large refractive index difference between Mo and Si EUV light, so that the reflectance at the interface between Si and Mo can be increased. It is used. The protective layer 3 made of Ru can serve as a stopper layer in the processing of the absorption layer 4 and a protective layer against a chemical solution in mask cleaning. When the protective layer 3 is made of Si, a buffer layer may be provided between the absorbing 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 when etching or pattern correction of the absorption layer 4, and is a nitrogen compound (CrN) of chromium (Cr). It consists of

(Absorption layer)
The absorption layer 4 of the reflective mask shown in FIG. 1A is composed of a tantalum (Ta) nitrogen compound (TaN) having a high absorption rate for EUV light. 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 of the reflective mask shown in FIG. 1A is an absorption layer having a two-layer structure in which a low reflection layer having an antireflection function with respect to ultraviolet light having a wavelength of 190 to 260 nm is provided on the upper layer. good. 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.

(Back conductive film)
The conductive film 5 of the reflective mask shown in FIG. 1A is generally made of CrN, but it only needs to be conductive and may be a material made of a metal material. In addition, the reflective mask shown in FIG. 1A has been described as having the conductive film 5, but a reflective mask without the conductive film 5 may be used.

(Shading area formation)
A method for forming a light shielding region of the reflective mask according to the present embodiment will be described. First, a light shielding region is formed on an EUV mask in which a pattern is formed in the pattern region 10 by lithography and etching.

By photolithography or electron beam lithography, a resist pattern in which only the light shielding region is opened is formed. Next, using the resist pattern as a mask, the absorption film 4 and the protective layer 3 are selectively removed by dry etching using a fluorine-based gas, a chlorine-based gas, or a mixed gas thereof as an etching gas. Next, the multilayer reflective layer 2 is selectively removed by dry etching using a fluorine-based gas, a chlorine-based gas, or a mixed gas thereof as an etching gas as an etching gas, or by wet etching using an alkaline solution or an acidic solution. .

As an etching gas for dry etching for selectively removing the multilayer reflective layer 2, a fluorine-based gas, a chlorine-based gas, or a mixed gas thereof is used for both Mo and Si that are materials of the multilayer reflective layer. This is because it has an etching property. Examples of the fluorine-based gas used at this time include CF ₄ , C ₂ F ₆ , C ₄ F ₈ , C ₅ F ₈ , CHF ₃ , SF ₆ , ClF ₃ , and the chlorine-based gas includes Cl ₂ , HCl etc. are mentioned.

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

  A stress reduction region is formed by applying a modification process to the multilayer reflective layer in the vicinity of the light shielding region with respect to the light shielding region in which the multilayer reflective layer is dug.

  As a modification treatment method for forming the stress reduction region, a laser beam that can be locally treated is preferable. There are many types of lasers, but they are suitable for processing depending on the characteristics of each laser, such as oscillation wavelength, pulse oscillation characteristics, condensing characteristics, output, and absorption to materials. Does not matter. It is important that energy is given locally and heat spread is small. In that respect, femtosecond laser, YAG laser, CO2 laser, etc. are suitable.

  In addition, as another modification processing method for forming the stress reduction region, a flash lamp that emits pulsed light in an extremely short time may be used. Since high energy is irradiated in a short time, the spread of heat can be suppressed.

  Further, ion beam irradiation or electron beam irradiation may be used as another modification treatment method for forming the stress reduction region. The feature of ion beams and electron beams is controllability that can be processed targeting a narrow area. As an ion source of a general ion beam irradiation apparatus, there are Ar, He, Ga, etc., but if an ion source (fluorine atom or the like) that reacts with and vaporizes Si and Mo, which are materials of a multilayer reflective layer, is used, Since it will be etched away, the ion source should just be a material which does not react and vaporize with Si and Mo.

  As described above, in the EUV mask having the multilayer reflective layer removal type light shielding region, since the stress reduction region is provided in the vicinity of the light shielding region, the position accuracy of the EUV mask pattern can be prevented from being lowered. A reflective mask having accuracy can be obtained.

  Hereinafter, a reflective mask manufacturing method according to a first embodiment of the present invention will be described with reference to the drawings.

  First, a reflective mask blank 201 as shown in FIG. This mask blank 201 has a Mo layer with a thickness of 2.8 nm and a thickness of 4.2 nm designed on the quartz substrate 1 so as to have a reflectance of about 64% with respect to EUV light with a wavelength of 13.5 nm. 40 pairs of multilayer reflective layers 2 of Si layers are formed, a protective layer 3 made of Ru with a thickness of 2.5 nm is formed thereon, and an absorption layer 4 made of TaSi with a thickness of 70 nm is further formed thereon. It has been made.

  Next, as shown in FIG. 2B, a positive chemically amplified resist 9 (FEP171: manufactured by FUJIFILM Electronics Materials) is applied to the mask blank 201 to a film thickness of 300 nm, and an electron beam lithography machine ( JBX9000 (manufactured by JEOL Ltd.) was used to draw a predetermined pattern. Then, PEB and spray development (SFG3000: manufactured by Sigma Meltech) at 110 ° C. for 10 minutes were performed to form a resist pattern 9a as shown in FIG.

Next, using the resist pattern 9a as a mask, after the absorption layer 4 is etched by dry etching using CF ₄ plasma and Cl ₂ plasma (FIG. 2D), the resist pattern 9a is peeled off and cleaned. A reflective mask 211 having the evaluation pattern (circuit pattern) shown in 2 (e) was produced. A top view of the reflective mask 211 is shown in FIG. In the evaluation pattern, a cross mark having a line width of 1 micron and a length of 5 microns for position accuracy measurement was arranged on the entire image field inside the mask from the light shielding region (FIG. 3B).

  At this stage (after the formation of the main pattern), the position accuracy of the pattern for measuring position accuracy was measured using a photomask position accuracy measuring apparatus IPRO2 (KLA).

  Thereafter, a light shielding region was formed outside the pattern region 10 (image field) of the reflective mask 211 having the above-described evaluation pattern. The process is as follows.

  First, the i-line resist layer 29 was applied with a film thickness of 500 nm on the surface of the reflective mask 211 shown in FIG. 4A (FIG. 4B). Next, a pattern is drawn on the i-line resist layer 29 by an i-line drawing machine (ALTA3000: manufactured by Applied Materials) and development is performed, thereby forming a resist pattern 29a from which a region that will later become a light-shielding region is removed. (FIG. 4C). At this time, the width of the opening of the resist pattern 29a was 3 mm.

  Next, the absorbing layer 4 is selectively removed by reactive ion etching (RIE) using fluorine plasma using the resist pattern 29a as a mask, and further etching is continued to select the protective layer 3 and the multilayer reflective layer 2 (Figure 4 (d)). The etching conditions are as follows.

Pressure in the etching chamber: 6.65 Pa
ICP (inductively coupled plasma) power: 500W
RIE power: 2000W
CHF3 flow rate: 20sccm
Processing time: 10 minutes Next, the resist pattern 29a is removed by washing with a sulfuric acid-based stripping solution and ammonia hydrogen peroxide solution, and a reflective mask having a light-shielding region is produced as shown in FIG. did.

  At this stage (after the formation of the light-shielding region), the position accuracy of the position accuracy measurement pattern was measured again using a photomask position accuracy measuring apparatus IPRO2 (KLA).

  Finally, in order to reduce the stress of the multilayer reflective layer in the vicinity of the light shielding region, laser irradiation (beam diameter 40 μm, output 8 A, scanning speed 2 cm / second, so as to hit only the range of 15 μm from the edge of the light shielding region, ) To obtain a reflective mask 101 shown in FIG. 4F (= FIG. 1A). Fig.5 (a) is the top view which looked at FIG.4 (f) from the top. FIG. 5B is an enlarged view of the pattern area (image field).

  At this stage (after the stress reduction process), the position accuracy of the pattern for measuring position accuracy was measured again using a photomask position accuracy measuring apparatus IPRO2 (KLA). All the positional accuracy measurement results measured so far are shown in the graph of FIG. It can be seen that the positional accuracy decreases after the formation of the light-shielding region, compared to the value after the formation of the main pattern. Furthermore, after the stress reduction region was formed, the lowered position accuracy was recovered to almost the same as after the main pattern was formed.

  Finally, a part of the light-shielding region of the reflective mask 101 produced as described above was cut, and a cross section was observed with a transmission electron microscope. As a result, one side of the side wall of the multilayer reflective layer in the light-shielding region was observed. In the range of about 15 μm, an altered layer in which the Si and Mo materials of the multilayer reflective layer were mixed (state where the interface was not clear) could be confirmed (FIG. 7B). On the other hand, FIG. 7A shows a normal EUV mask with a light shielding region in which no stress reduction region is formed, and the difference from the reflective mask of Example 1 can be clearly recognized.

  Thus, in Example 1, a reflective mask having a multilayer reflective layer digging type light shielding region with high pattern position accuracy could be produced.

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

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Multilayer reflection layer, 3 ... Protective layer, 4 ... Absorption layer, 5 ... Back surface electrically conductive film, 9 ... Resist, 9a ... Resist pattern, 10 ... Pattern area | region, 11 ... Light-shielding area | region, 12 ... Stress reduction area | region , 29 ... resist, 29a ... resist pattern, 101 ... reflective mask obtained in Example 1, 201 ... reflective mask blank, 211 ... reflective mask on which a circuit pattern is formed, 31a ... photograph by transmission electron microscope (usually) Reflective mask substrate)
31b: Photo by transmission electron microscope (substrate in the stress-reduced region of the reflective mask produced in Example 1)
32a: Photograph by transmission electron microscope (multilayer reflective layer of a normal reflective mask)
32b: Photo by transmission electron microscope (multilayer reflective layer in the stress reduction region of the reflective mask produced in Example 1)

Claims (11)

  A multilayer reflection layer formed on the substrate surface; and an absorption layer formed on the multilayer reflection layer and having a circuit pattern, wherein the absorption layer and the multilayer reflection layer are outside the region of the circuit pattern. A reflective mask, wherein a removed light shielding region is formed, and a stress reduction region in which internal stress is reduced is formed in a multilayer reflective layer in the vicinity of the light shielding region.   2. The reflective mask according to claim 1, wherein the stress reducing region in the vicinity of the light shielding region has an internal stress of the multilayer reflective layer of 100 MPa or less at a distance of at least 15 μm from the edge of the light shielding region.   3. The method of manufacturing a reflective mask according to claim 1, wherein the multilayer reflective layer is selectively dry-etched or wet-etched after the absorption layer is selectively removed. A method for manufacturing a reflective mask, comprising: forming a light-shielding region formed in the step, and then forming a stress reduction region by locally modifying only the vicinity of the light-shielding region.   4. The method of manufacturing a reflective mask according to claim 3, wherein the modification processing method for forming the stress reduction region includes locally irradiating laser light only in the vicinity of the light shielding region.   4. The method of manufacturing a reflective mask according to claim 3, wherein in the modification processing method for forming the stress reduction region, the flash lamp is locally irradiated only in the vicinity of the light shielding region.   4. The method of manufacturing a reflective mask according to claim 3, wherein in the modification processing method for forming the stress reduction region, only the vicinity of the light shielding region is locally irradiated with an ion beam or an electron beam.   The method of manufacturing a reflective mask according to claim 3, wherein the dry etching is performed using a gas containing fluorine or chlorine as an etching gas. The etching gas containing fluorine is a gas containing at least one selected from the group consisting of CF ₄ , C ₂ F ₆ , C ₄ F ₈ , C ₅ F ₈ , CHF ₃ , SF ₆ , and ClF _3. A method of manufacturing a reflective mask according to claim 7.   9. The method of manufacturing a reflective mask according to claim 7, wherein the etching gas containing chlorine is a gas containing at least one selected from the group consisting of Cl and HCl.   The wet etching is performed using an etching solution containing at least one selected from the group consisting of nitric acid, phosphoric acid, hydrofluoric acid, sulfuric acid, and acetic acid. A method for manufacturing a reflective mask.   5. The method of manufacturing a reflective mask according to claim 4, wherein the laser light is performed using a laser including at least one selected from the group consisting of a femtosecond laser, a YAG laser, and a CO2 laser.