JP2007183120A - Multilayer mirror, manufacturing method, exposure unit and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer mirror, having internal stresses reduced and restrained from changing with the elapse of time. <P>SOLUTION: The multilayer mirror 1 comprises a substrate SB and a multilayer film 10 formed on the substrate, by alternately laminating silicon and molybdenum, and reflects a light with a wavelength of 20 nm or shorter. The multilayer film 10 is composed of a combination of the first layer 12, having tensile stress and the second layer 14 having a compression stress laminated, in this order, on the substrate SB. The first layer 12 has a specified cyclic structure, consisting of a molybdenum film 12a and a silicon film 12b, and is annealed, after the formation of the layer on the substrate SB. Similarly, the second layer 14 has a specified cyclic structure consisting of a molybdenum film 14a and a silicon film 14b, and the multilayer 10 is annealed at specified conditions, after formation of the layer 14 on the first layer 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to a multilayer mirror, and more particularly to a multilayer mirror used in an exposure apparatus that exposes an object to be processed such as a single crystal substrate for a semiconductor wafer and a glass substrate for a liquid crystal display (LCD). . The present invention is suitable, for example, for an exposure apparatus that uses EUV (Extreme Ultraviolet) light (soft X-ray) as an exposure light source.

  In order to efficiently transfer a very fine circuit pattern of 0.1 μm or less, an exposure apparatus using EUV light (soft X-ray) having a wavelength shorter than that of ultraviolet light and having a wavelength of about 11 nm to 14 nm (hereinafter, “ "EUV exposure apparatus" has been developed.

  The refractive index of a substance with respect to the wavelength region of EUV light is very close to 1, and its absorption is very large. Accordingly, in the wavelength region of EUV light, in principle, a refractive optical element utilizing light refraction (lens action) such as that used in visible light or ultraviolet light cannot be used. Therefore, in the wavelength region of EUV light, a reflective optical element (reflective optical system) using light reflection is used.

  Two types of reflective optical elements used in an EUV exposure apparatus have different optical constants (relatively little absorption in the wavelength region of EUV light and a large refractive index difference between them) on a substrate having a small coefficient of thermal expansion. There is a multilayer mirror in which these materials are alternately laminated. An EUV exposure apparatus generally uses a multilayer mirror having a Mo / Si multilayer film in which Mo (molybdenum) and silicon (Si) are alternately stacked.

  Such a multilayer film is produced by sputtering or vapor deposition. However, the Mo / Si multilayer film produced by the sputtering method generally has a compressive stress on the order of several hundred MPa as the internal stress. Since the internal stress generated in the Mo / Si multilayer film deforms the multilayer mirror substrate, it causes wavefront aberration and adversely affects optical performance. Also, the internal stress changes with time. Such a change with time occurs regardless of the initial value of the internal stress. For example, even if the internal stress is suppressed to zero, the change will proceed. When the present inventor made a 300 nm Mo / Si multilayer film and continued to observe the internal stress value, a stress change of 40 MPa was observed in 100 days.

Thus, several techniques for reducing the internal stress of the Mo / Si multilayer film have been proposed (see, for example, Patent Document 1, Non-Patent Documents 1 and 2). Patent Document 1 and Non-Patent Document 1 propose that the internal stress is changed from compression to tension by performing heat treatment (annealing) after forming the Mo / Si multilayer film. In addition, a method of offsetting internal stress by laminating another thin film having tensile stress (hereinafter referred to as “stress adjusting layer”) between the multilayer film and the substrate has been proposed. Specifically, Non-Patent Document 2 discloses that a Mo / Si multilayer having a small internal stress is formed by laminating another Mo / Si multilayer having a different Mo film thickness ratio between the Mo / Si multilayer and the substrate. A film is produced.
US Pat. No. 6,309,705 B1 Jpn. J. et al. Appl. Phys. Vol. 41 (2002) p. 4802-4805 SPIE 2004 vol. 5374.101-111

  However, the method of annealing after forming the Mo / Si multilayer film can change the internal stress from compression to tension, but at the same time, causes a decrease in reflectance. Non-Patent Document 1 also suggests that the reflection peak wavelength shifts due to the compression of the film thickness depending on the annealing temperature in addition to the decrease in reflectance. In other words, annealing can reduce internal stress while adversely affecting optical performance.

  On the other hand, in the method of laminating the stress adjustment layer between the multilayer film and the substrate, the number of layers and the internal stress of the stress adjustment layer formed first cannot be adjusted after the multilayer film is formed. Therefore, depending on the reproducibility of the internal stress of the multilayer film to be formed later, an internal stress of the order of several tens of MPa may remain, which is insufficient to suppress the deformation of the substrate. Furthermore, it is not possible to suppress changes with time in internal stress.

  Accordingly, an object of the present invention is to provide a multilayer mirror that reduces internal stress and suppresses changes in internal stress over time.

  In order to achieve the above object, a multilayer mirror according to one aspect of the present invention has a multilayer film in which silicon and molybdenum are alternately stacked on a substrate and reflects light having a wavelength of 20 nm or less. In the mirror, the multilayer film includes, in order from the substrate side, a first layer having a tensile stress and a second layer having a compressive stress.

  A manufacturing method according to another aspect of the present invention is a manufacturing method of a multilayer mirror that reflects light having a wavelength of 20 nm or less, and a step of forming a first layer in which silicon and molybdenum are alternately stacked; Annealing the first layer at a temperature higher than the deposition temperature of the first layer; and a second layer in which silicon and molybdenum are alternately stacked on the annealed first layer. Forming a film; and annealing the first layer and the second layer at a temperature higher than a film forming temperature of the second layer.

  The manufacturing method as still another aspect of the present invention includes a multilayer film having a first layer and a second layer in which silicon and molybdenum are alternately laminated, and reflects light having a wavelength of 20 nm or less. A method for manufacturing a mirror, the step of converting the compressive stress of the first layer into a tensile stress, and the first layer and the second layer at a temperature higher than a film forming temperature of the second layer. And an annealing step.

  A multilayer mirror according to still another aspect of the present invention is manufactured using the above-described manufacturing method.

  An optical system according to still another aspect of the present invention includes a plurality of optical elements, and at least one of the plurality of optical elements includes the multilayer mirror described above.

  An exposure apparatus according to still another aspect of the present invention is characterized in that the object to be processed is exposed by irradiating the object with light through the multilayer mirror described above.

  An exposure apparatus according to still another aspect of the present invention is an exposure apparatus that exposes a reticle pattern onto an object to be processed, an illumination optical system that illuminates the reticle with light from a light source, and the reticle pattern as the reticle pattern. A projection optical system for projecting onto the object to be processed, and the optical element constituting the illumination optical system and the projection optical system is the multilayer mirror described above.

  According to still another aspect of the present invention, there is provided a device manufacturing method comprising: exposing a target object using the above-described exposure apparatus; and developing the exposed target object.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  ADVANTAGE OF THE INVENTION According to this invention, while reducing internal stress, the multilayer film mirror which suppressed the temporal change of internal stress can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing a configuration of a multilayer mirror 1 as one aspect of the present invention.

  As shown in FIG. 1, the multilayer mirror 1 has a multilayer film 10 in which Mo (molybdenum) and silicon (Si) are alternately laminated on a substrate SB, and has a wavelength of 20 nm or less (EUV light). To reflect.

  The multilayer film 10 includes a first layer 12 and a second layer 14 in order from the substrate SB side. In other words, the multilayer film 10 includes the first layer 12 having a constant periodic structure of the Mo film 12a and the Si film 12b, and the second layer having a constant periodic structure of the Mo film 14a and the Si film 14b. 14 in combination.

  The first layer 12 has a tensile stress. As will be described later, the first layer 12 is formed on the substrate SB and then annealed. Thereby, the internal stress of the first layer 12 is converted from compressive stress to tensile stress, and the change with time is also suppressed. In consideration of compression of the film thickness at the time of annealing, the Mo film 12a or the Si film 12b is laminated thickly, so that the period length of the first layer 12 (that is, the first layer 12 after annealing). Can be kept within a desired value. Further, the value of the tensile stress and the film thickness compression amount of the first layer 12 can be controlled by changing the annealing temperature. If the annealing temperature is higher than the deposition temperature of the first layer 12, the compressive stress can be weakened. On the other hand, if the annealing temperature is lower than the first film formation temperature, there is almost no stress reduction effect due to annealing (heating). Here, the periodic length is a value obtained by adding the thicknesses of two kinds of substances in a certain periodic structure (that is, in the first layer 12, the film thickness of the Mo film 12a and the film thickness of the Si film 12b). And a).

  The second layer 14 is formed on the first layer 12 (the annealed first layer 12) and has a compressive stress. When the second layer 14 is formed, the compressive stress of the second layer 14 can be offset by the tensile stress of the first layer 12, but the second layer 14 changes with time, so that time As the process progresses, the equilibrium will be lost. Therefore, in the multilayer mirror 1, after the second layer 14 is formed, the multilayer film 10 is annealed again to suppress the change with time. Thereby, residual compressive stress can also be removed. The annealing temperature only needs to be higher than the film formation temperature of the second layer 14, and is a temperature at which residual compressive stress can be removed and the change with time can be suppressed (stopped).

  Hereinafter, a specific configuration of the multilayer mirror 1 of the present invention (film configuration of the multilayer film 10) and various characteristics (internal stress, reflectance, etc.) of the multilayer mirror 1 will be described. The manufacturing method 100 of the multilayer mirror 1 will also be described with reference to FIGS. FIG. 2 is a flowchart for explaining a manufacturing method 100 of the multilayer mirror 1 as one aspect of the present invention. FIG. 3 is a graph showing changes in internal stress with respect to temperature in each step of the multilayer mirror 1 manufactured by the manufacturing method 100 shown in FIG. In FIG. 3, the internal stress [MPa] is adopted on the vertical axis and the temperature [° C.] is adopted on the horizontal axis.

  First, the first film 12 composed of alternating layers of the Mo film 12a and the Si film 12b is formed on the substrate SB made of Si (step 102). In this embodiment, a Si wafer is used as the substrate SB. Note that the temperature of the substrate SB during the formation of the first layer 12 (that is, the film formation temperature) is 40 ° C. The film thicknesses of the Mo film 12a and the Si film 12b were set so as to have film thicknesses having a reflection peak with respect to EUV light in the vicinity of a wavelength of 13 nm after compression in consideration of compression by annealing described later. The number of layers of the first film 12 is 80, and the final layer is the Si film 12b. As shown in FIG. 4, the first layer 12 of the present embodiment had a compressive stress immediately after film formation. Here, FIG. 4 is a diagram showing the period length and internal stress of each layer in each step of the multilayer mirror 1.

  After the formation of the first layer 12, the first layer 12 is annealed (heated) in a vacuum atmosphere or an inert gas atmosphere (step 104). Note that the entire substrate SB on which the first layer 12 is formed may be annealed, or only the first layer 12 may be annealed. Annealing includes, for example, heating by radiant heat and heating by laser irradiation in a vacuum atmosphere, and heating using a gas as a heat transfer medium in an inert gas atmosphere, but is not limited thereto. In the present embodiment, the first layer 12 is directly heated using a heater in a nitrogen atmosphere.

  When annealing is performed at a temperature higher than the film formation temperature of the first layer 12, the compressive stress (negative value shown in FIG. 4) changes to tensile stress (positive value shown in FIG. 4). In the present embodiment, it is confirmed that a change in internal stress is caused by annealing at a temperature of 50 ° C. or higher, and a tensile stress is generated beyond the state where the internal temperature is 0 by annealing at a temperature of 300 ° C. or higher ( (Converted to tensile stress). Therefore, if annealing is performed at a temperature higher than the film formation temperature of the first layer 12, it can be said that there is an effect of converting the compressive stress into the tensile stress (changing in the tensile direction). FIG. 5 shows the relationship between the amount of change in internal stress due to annealing and the annealing temperature. In FIG. 5, the amount of change in internal stress [MPa] is adopted on the vertical axis and the annealing temperature [° C.] is adopted on the horizontal axis.

  The amount of change in internal stress due to annealing also changes depending on the rate of temperature rise and the constant temperature holding time. As a result of experiments using a large number of samples, it was confirmed that, under the same conditions as in this embodiment, when the rate of temperature increase was 5 ° C./min, the amount of change was saturated at a constant temperature holding time of 60 minutes. FIG. 5 shows the results obtained with a temperature rising rate of 5 ° C./minute and a constant temperature holding time of 60 minutes. In the present embodiment, since the initial value of the internal stress was −381 MPa (see FIG. 3), the annealing temperature was set to 350 ° C. in order to develop the tensile stress.

  As described above, annealing causes the film thickness of the multilayer film 10 (in this case, the first layer 12) to be compressed. However, since the amount of compression varies depending on the annealing temperature, the thickness after annealing can be kept within a desired value by reflecting the amount of compression on the design value of the film thickness. FIG. 6 and FIG. 7 show the relationship between the compression amount of the periodic length of the multilayer film 10 (first layer 12) and the annealing temperature. 6 shows the compression amount of the periodic length of the multilayer film 10 (first layer 12) with respect to the annealing temperature of 100 ° C. or higher, and FIG. 7 shows the multilayer film 10 (first layer with respect to the annealing temperature of 100 ° C. or lower. 12) shows the compression amount of the period length. 6 and 7 employ a period length compression amount [nm] on the vertical axis and a temperature [° C.] on the horizontal axis.

  Steps 102 and 104 produce a first layer 12 having a tensile stress. In this embodiment, as shown in FIG. 4, the first layer 12 having a tensile stress of 130 MPa was manufactured.

  Next, the second layer 14 is formed on the annealed first layer 12 (step 106). Similar to the first layer 12, the second layer 14 is an alternating layer of the Mo film 14a and the Si film 14b, and has a thickness that takes into account the amount of compression due to annealing. In the present embodiment, the number of second layers 14 is 24.

  The second layer 14 also has a compressive stress, but is canceled by the tensile stress of the first layer 12 serving as a base. Therefore, when the second layer 14 is formed alone as the multilayer film 10 as a whole, the second layer 14 has a compressive stress. Compared with the compressive stress is small. In the present embodiment, as shown in FIG. 4, an internal stress of −25 MPa remains in the entire multilayer film 10. Although the internal stress remaining in the multilayer film 10 is small but not negligible, and as it is, the internal stress of the second layer 14 changes with time, so that the optical characteristics of the multilayer mirror 1 deteriorate due to changes in the surface shape. End up.

  Therefore, the multilayer film 10 (that is, the first layer 12 and the second layer 14) is annealed (step 108). The purpose of the annealing is to suppress the temporal change of the internal stress of the second layer 14 and to remove the internal stress remaining in the multilayer film 10. An experiment was conducted using a large number of samples, and under the conditions of a temperature rising rate of 5 ° C./min and a constant temperature holding time of 60 minutes, if the annealing temperature was 100 ° C. or higher, the change over time was obtained. It was. In the present embodiment, the multilayer film 10 is annealed at 105 ° C. because of the internal stress remaining in the multilayer film 10. The first layer 12 has been annealed once in step 104, but even if it is annealed again at a temperature lower than the annealing temperature, no change in internal stress or compression of the film thickness occurs. Also in this embodiment, it was confirmed that the periodic length of the first layer 12 did not change.

  On the other hand, when the multilayer film 10 is annealed, there is a problem that the reflectivity for EUV light is reduced. As shown in FIG. 8, the higher the annealing temperature for the multilayer film 10, the greater the decrease in reflectance. FIG. 8 is a graph showing the relationship between the amount of decrease in the reflectance of the multilayer mirror 1 and the annealing temperature. In FIG. 8, the vertical axis employs the reflectance reduction amount [%] and the horizontal axis employs the annealing temperature [° C.].

  In this embodiment, since the compressive stress of the second layer 14 is offset to some extent by the tensile stress of the first layer 12, the annealing temperature for the multilayer film 10 after the second layer 14 is formed is Can be lowered. Therefore, the reflectance of the second layer 14 that is located above the multilayer film 10 (on the light incident side) and greatly contributes to the reflection of light can be maintained high. In this embodiment, since the multilayer film 10 is annealed at 105 ° C., the amount of decrease in the reflectance is about 0.1%.

  Further, as described above, the periodic length of the first layer 12 is designed so as to have a reflection peak with respect to EUV light in the vicinity of a wavelength of 13 nm. Therefore, the multilayer mirror 1 having a reflection peak with respect to EUV light having a specific wavelength as the entire multilayer film 10 can be manufactured.

  The result of annealing the entire multilayer film 10 after forming the second layer 14 is shown in FIG. In other words, FIG. 9 is a graph obtained by extracting the step of annealing at 105 ° C. from FIG. As is clear from FIGS. 4 and 9, it can be confirmed that the multilayer mirror 1 of the present embodiment suppresses the internal stress of the multilayer film 10 to a low value of −1 MPa.

  As described above, in the multilayer mirror 1 of the present invention, the maximum value of the reflectance with respect to EUV light having a wavelength of 13.0 nm to 14.0 nm can be suppressed to 60% or more, and the internal stress of the multilayer film can be suppressed to within ± 10 MPa. it can. Moreover, the manufacturing method 100 can manufacture such a multilayer mirror. In addition, since the multilayer mirror manufactured by the multilayer mirror 1 and the manufacturing method 100 can suppress the change of internal stress with time, it can prevent the optical performance from being deteriorated due to the deformation of the substrate.

  Hereinafter, an exemplary exposure apparatus 200 of the present invention will be described with reference to FIG. Here, FIG. 10 is a schematic sectional view showing the structure of the exposure apparatus 200 of the present invention. The exposure apparatus 200 of the present invention is a projection exposure apparatus that uses EUV light (for example, a wavelength of 13.4 nm) as exposure illumination light. The exposure apparatus 200 exposes the processing object 240 with a circuit pattern formed on the mask 220 by, for example, the step-and-repeat method or the step-and-scan method.

  The exposure apparatus 200 includes an illumination device 210, a mask stage 225 on which a mask 220 is placed, a projection optical system 230, a wafer stage 245 on which an object 240 is placed, an alignment detection mechanism 250, and a focus position detection mechanism. 260.

  Further, as shown in FIG. 7, a vacuum chamber VC is provided so that at least the optical path through which the EUV light passes is a vacuum environment. This is because EUV light has a low transmittance to the atmosphere and generates contaminants due to a reaction with a residual gas (polymer organic gas or the like) component.

  The illumination device 210 is an illumination device that illuminates the mask 220 with arcuate EUV light corresponding to the arcuate field of view of the projection optical system 230, and includes an EUV light source 212 and an illumination optical system 214.

  The illumination optical system 214 includes a condensing mirror 214a and an optical integrator 214b. The condensing mirror 214a serves to collect EUV light emitted from the laser plasma almost isotropically. The optical integrator 214b has a role of uniformly illuminating the mask 220 with a predetermined numerical aperture. The illumination optical system 214 may have an aperture for limiting the illumination area of the mask 220 to an arc shape at a position conjugate with the mask 220. A reflective optical element (such as a condensing mirror 212a) that constitutes the illumination optical system 214 is a multilayer mirror manufactured by the multilayer mirror 1 or the manufacturing method 100 of the present invention. Thereby, the illumination optical system 214 can exhibit excellent optical performance.

  The mask 220 is a reflective mask, on which a circuit pattern (or image) to be transferred is formed, and is supported and driven by a mask stage 225. Diffracted light emitted from the mask 220 is reflected by the projection optical system 230 and projected onto the object 240. The mask 220 and the workpiece 240 are arranged in an optically conjugate relationship. Since the exposure apparatus 200 is a step-and-scan exposure apparatus, the pattern of the mask 220 is reduced and projected onto the object 240 by scanning the mask 220 and the object 240.

  The mask stage 225 supports the mask 220 and is connected to a moving mechanism (not shown). Any structure known in the art can be applied to the mask stage 225. The exposure apparatus 200 scans the mask 220 and the workpiece 240 in a synchronized state. Here, X is the scanning direction within the surface of the mask 220 or the object to be processed 240, Y is the direction perpendicular thereto, and Z is the direction perpendicular to the surface of the mask 220 or object 240.

  The projection optical system 230 uses the plurality of reflection mirrors 230a to reduce and project the pattern on the mask 220 surface onto the object 240 to be processed disposed on the image plane. A reflective optical element (such as a reflective mirror 730a) constituting the projection optical system 230 is a multilayer mirror manufactured by the multilayer mirror 1 or the manufacturing method 100 of the present invention. Thereby, the projection optical system 230 can exhibit excellent optical performance.

  The wafer stage 245 supports the workpiece 240 via the wafer chuck 245a. The mask 220 and the workpiece 240 are scanned synchronously.

  The alignment detection mechanism 250 measures the positional relationship between the position of the mask 220 and the optical axis of the projection optical system 230, and the positional relationship between the position of the object 240 to be processed and the optical axis of the projection optical system 230. Further, the alignment detection mechanism 250 sets the positions and angles of the mask stage 225 and the wafer stage 245 so that the projected image of the mask 220 matches a predetermined position of the workpiece 240.

  The focus position detection mechanism 260 measures the focus position in the Z direction on the surface of the object 240 to be processed and controls the position and angle of the wafer stage 245 so that the surface of the object 240 to be processed is always projected by the projection optical system 230 during exposure. Keep at the imaging position.

  In exposure, the EUV light emitted from the illumination device 210 illuminates the mask 220 and forms a pattern on the surface of the mask 220 on the surface of the object 240 to be processed. In the present embodiment, the image surface is an arc-shaped (ring-shaped) image surface, and the entire surface of the mask 220 is exposed by scanning the mask 220 and the workpiece 240 at a speed ratio of the reduction ratio.

  The illumination optical system 214 and the projection optical system 230 used by the exposure apparatus 200 include the multilayer mirror manufactured by the multilayer mirror 1 or the manufacturing method 100 of the present invention. Therefore, the illumination optical system 214 and the projection optical system 230 reflect EUV light with a high reflectance and have excellent imaging performance. Thereby, the exposure apparatus 200 can provide a high-quality device (semiconductor element, LCD element, imaging element (CCD, etc.), thin film magnetic head, etc.) with high throughput and high cost efficiency.

  Next, an example of a device manufacturing method using the above-described exposure apparatus 200 will be described with reference to FIGS. FIG. 11 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, etc.). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), a device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique of the present invention using the mask and the wafer. Step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer created in step 4. The assembly process (dicing, bonding), packaging process (chip encapsulation), and the like are performed. Including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (step 7).

  FIG. 12 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is transferred onto the wafer by the exposure apparatus 200 described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. According to this device manufacturing method, it is possible to manufacture a higher quality device than before. Thus, the device manufacturing method using the exposure apparatus 200 and the resulting device also constitute one aspect of the present invention.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

It is a schematic sectional drawing which shows the structure of the multilayer film mirror as 1 side surface of this invention. It is a flowchart for demonstrating the manufacturing method of the multilayer film mirror as 1 side surface of this invention. It is a graph which shows the change with respect to the temperature of the internal stress in each process of the multilayer mirror manufactured by the manufacturing method shown in FIG. It is a figure which shows the periodic length and internal stress of each layer in each process of a multilayer film mirror. It is a graph which shows the relationship between the variation | change_quantity of the internal stress by annealing, and the temperature of annealing. It is a graph which shows the relationship between the compression amount of the period length of a multilayer film (1st layer), and the temperature (100 degreeC or more) of annealing. It is a graph which shows the relationship between the compression amount of the periodic length of a multilayer film (1st layer), and the temperature (100 degrees C or less) of annealing. It is a graph which shows the relationship between the fall amount of the reflectance of a multilayer film mirror, and the temperature of annealing. It is a graph which shows the result of annealing the whole multilayer film after forming the second layer. It is a schematic sectional drawing which shows the structure of the exposure apparatus as one side surface of this invention. It is a flowchart for demonstrating manufacture of devices (semiconductor chips, such as IC and LSI, LCD, CCD, etc.). 9 is a detailed flowchart of the wafer process in Step 4 shown in FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer film 10 Multilayer film 12 1st layer 12a Mo film 12b Si film 14 2nd layer 14a Mo film 14b Si film SB Substrate 200 Exposure apparatus 210 Illumination apparatus 212 EUV antigen 214 Illumination optical system 214a Condensing mirror 220 Mask 225 Mask stage 230 Projection optical system 230a Reflection mirror 240 Object 245 Wafer stage 250 Alignment detection mechanism 260 Focus position detection mechanism

Claims (12)

A multilayer mirror that has a multilayer film in which silicon and molybdenum are alternately laminated on a substrate and reflects light having a wavelength of 20 nm or less,
The multilayer film is sequentially from the substrate side.
A first layer having a tensile stress;
And a second layer having a compressive stress.   2. The multilayer mirror according to claim 1, wherein the periodic length of the first layer is the same as the periodic length of the second layer. A method of manufacturing a multilayer mirror that reflects light having a wavelength of 20 nm or less,
Forming a first layer in which silicon and molybdenum are alternately laminated;
Annealing the first layer at a temperature higher than the deposition temperature of the first layer;
Depositing a second layer of alternately laminated silicon and molybdenum on the annealed first layer;
Annealing the first layer and the second layer at a temperature higher than the film formation temperature of the second layer.   The film forming step forms the first layer and the second layer so that the periodic length of the first layer and the periodic length of the second layer are the same. The manufacturing method according to claim 3. A method of manufacturing a multilayer mirror having a multilayer film having a first layer and a second layer in which silicon and molybdenum are alternately laminated and reflecting light having a wavelength of 20 nm or less,
Converting the compressive stress of the first layer into a tensile stress;
Annealing the first layer and the second layer at a temperature higher than the film formation temperature of the second layer.   The manufacturing method according to claim 5, wherein in the conversion step, the first layer is annealed at a temperature higher than a film forming temperature of the first layer.   A multilayer mirror manufactured using the manufacturing method according to claim 3. Having a plurality of optical elements,
An optical system comprising: the multilayer mirror according to claim 1, wherein at least one optical element among the plurality of optical elements.   An exposure apparatus that exposes a target object by irradiating the target object with light through the multilayer mirror according to any one of claims 1, 2, and 7. An exposure apparatus that exposes a reticle pattern onto an object to be processed,
An illumination optical system that illuminates the reticle with light from a light source;
A projection optical system for projecting the reticle pattern onto the object to be processed;
8. The exposure apparatus according to claim 1, wherein the optical element constituting the illumination optical system and the projection optical system is the multilayer mirror according to any one of claims 1, 2, and 7.   11. The exposure apparatus according to claim 9, wherein the light has a wavelength of 20 nm or less. Exposing the object to be processed using the exposure apparatus according to any one of claims 9 to 11,
And developing the exposed object to be processed.