JP2004177331A - Mirror for measuring position and mirror member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mirror for measuring a position at high measurement accuracy and a mirror member, which can reduce the weight, without causing difficulty or deterioration in characteristics. <P>SOLUTION: The mirrors 4 and 5 for measuring the position are provided to a sample stage for horizontally holding a sample, and reflect irradiation light to obtain the reflected light for measuring the position. A mirror main body 11 and a reflective film 12 provided on the surface thereof are provided. The mirror main body 11 is composed of low thermal expansion ceramics, by joining a first member 13 and a second member 15 or 15', at least one of which has a groove part 14 or 14', with a joining member 16 consisting of the low thermal expansion ceramics having a melting point lower than that of the low thermal expansion ceramics constituting them, so that the groove part 14 or 14' becomes a hollow part. The surface roughness Ra of the surface on which the reflective film 12 is formed is equal to or less than 10 nm. <P>COPYRIGHT: (C)2004,JPO

Description

【００５６】
【表２】

【００５７】
【発明の効果】
以上説明したように、本発明によれば、低熱膨張セラミックスからなるとともに少なくとも一方に溝部を有する第１の部材および第２の部材を、当該溝部が中空部となるように、これらを構成する低熱膨張セラミックスよりも溶融温度の低い低熱膨張セラミックスからなる接合材で接合してミラー本体を形成し、または、低熱膨張セラミックスからなる、多孔質の第１の部材および前記反射膜が形成される面を有する緻密質の第２の部材を、これらを構成する低熱膨張セラミックスよりも溶融温度の低い低熱膨張セラミックスからなる接合材で接合してミラー本体を形成し、かつ前記反射膜が形成される面の表面粗さがＲａで１０ｎｍ以下としたので、十分なミラー特性を確保しつつ、困難性や特性の劣化をもたらすことなく軽量化を図ることができ、測定精度の高い位置測定用ミラーを得ることができる。
【図面の簡単な説明】
【図１】本発明の位置測定用ミラーが搭載された露光装置用ステージ機構を示す平面図。
【図２】本発明の位置測定用ミラーを示す側面図。
【図３】本発明の第１の実施形態に係る位置測定用ミラーを示す部分断面斜視図。
【図４】本発明の第２の実施形態に係る位置測定用ミラーを示す部分断面斜視図。
【符号の説明】
１；ステージ
２；Ｘ方向モータ
３；Ｙ方向モータ
４，５；ミラー
６；Ｘ方向位置測定用レーザー干渉計
７；Ｙ方向位置測定用レーザー干渉計
１０；半導体ウエハ
１１；ミラー本体
１２；反射膜
１３，２３；第１の部材
１５，１５′，２４；第２の部材
１６，２５；接合材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a position measurement mirror and a mirror member provided on a sample stage such as a stage of an exposure apparatus that horizontally holds a sample, and reflects irradiation light to obtain reflected light for position measurement to perform precise alignment. About.
[0002]
[Prior art]
In recent years, semiconductor circuits have become increasingly finer and more highly integrated. With this trend, higher precision is required for exposure apparatuses, and alignment errors during exposure may lead to improved product quality and improved yield. The problem is how to perform alignment with high accuracy during exposure.
[0003]
Since the position measurement for alignment at the time of this exposure is performed by reflecting the laser light with a mirror to obtain reflected light for position measurement, the measurement accuracy at that time is such a position measurement accuracy. Alumina, silicon nitride, and the like, which have a smaller coefficient of thermal expansion than metal, have been used as the material of the mirror.
[0004]
However, with recent rapid miniaturization of semiconductor circuits, alumina or silicon nitride as a mirror material has a thermal expansion coefficient that is not sufficient and it is becoming difficult to obtain required accuracy.
[0005]
On the other hand, Patent Document 1 discloses a low thermal expansion ceramic mainly composed of cordierite as a material applicable as a stage position measuring mirror. Low thermal expansion ceramics mainly composed of cordierite have stable thermal expansion coefficient of 1 × 10 ^-6 / ° C or less, and exhibits higher rigidity than glass, so that more excellent mirror characteristics can be obtained.
[0006]
[Patent Document 1]
JP-A-11-209171
[0007]
[Problems to be solved by the invention]
However, with the increase in the size of the exposure apparatus due to the increase in the size of the semiconductor wafer and the mask material, an increase in the weight of the apparatus components poses a problem. In particular, the position measuring mirror is long and has a length of 500 to 1200 mm. Therefore, the positioning accuracy when the stage is moved / stopped is reduced due to the weight thereof, so that further weight reduction is required.
[0008]
As a method for reducing the weight of the position measurement mirror, it is conceivable to make the inside of the mirror into a hollow structure. However, it is very difficult to make ceramics into a hollow structure by machining. In addition, although a method of bonding the lid member to the member provided with the groove by glass is also conceivable, in the case of a long shape, the flatness of the reflecting surface changes with time due to residual stress due to a difference in thermal expansion between the base material and the bonding layer. This causes measurement accuracy to decrease over time. In addition, since the rigidity of glass is low, the rigidity of the entire member after joining is reduced, and distortion during high-speed movement causes a decrease in productivity.
[0009]
Further, a method of reducing the weight by bonding or mechanically fixing the reflecting portion of the mirror to a lightweight base can be considered, but high measurement accuracy cannot be obtained due to a difference in thermal expansion between the lightweight base and the mirror reflecting portion.
[0010]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a position measurement mirror and a mirror member that can be reduced in weight without causing difficulty or deterioration of characteristics and have high measurement accuracy. Aim.
[0011]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, (1) a member having a groove with low thermal expansion ceramics and a member for closing the groove are formed, and these members are formed of low thermal expansion ceramics constituting these members. By using as a mirror body or a mirror member by joining with a joining material made of a low thermal expansion ceramic having a lower melting temperature, and (2) having a surface on which a porous member and a reflective film are formed of the low thermal expansion ceramic By joining dense members with a joining material made of low-thermal-expansion ceramics whose melting temperature is lower than that of the low-thermal-expansion ceramics that compose them, difficulties in machining, a difference in coefficient of thermal expansion and low rigidity arise It has been found that the weight can be reduced without the need.
[0012]
The present invention has been completed based on such knowledge, and provides the following (1) to (12).
(1) A position measuring mirror that is provided on a sample stage that holds a sample horizontally and obtains reflected light for position measurement by reflecting irradiation light, comprising: a mirror main body; and a reflecting film provided on the surface thereof. The mirror body is made of a low thermal expansion ceramic, which is made of a low thermal expansion ceramic and has a groove in at least one of the first member and the second member so that the groove becomes a hollow portion. A mirror for position measurement, wherein the mirror is bonded with a bonding material made of a low thermal expansion ceramic having a low melting temperature, and the surface on which the reflective film is formed has a surface roughness Ra of 10 nm or less.
(2) A position measuring mirror provided on a sample stage for holding a sample horizontally, which reflects reflected light to obtain reflected light for position measurement, comprising: a mirror main body; and a reflecting film provided on the surface thereof. The mirror body is made of a low-thermal-expansion ceramic made of a low-thermal-expansion ceramic, and a porous first member and a dense second member having a surface on which the reflective film is formed. A mirror for position measurement, wherein the mirror is bonded with a bonding material made of a low thermal expansion ceramic having a low melting temperature, and the surface on which the reflective film is formed has a surface roughness Ra of 10 nm or less.
(3) In the above (1) and (2), the average thermal expansion coefficient of the mirror body at 20 to 30 ° C. is −1 × 10. ^-6 ~ 1 × 10 ^-6 / ° C.
(4) In the above (1) to (3), the low thermal expansion ceramics constituting the first and second members and the low thermal expansion ceramics constituting the bonding material are all lithium aluminosilicate, potassium zirconium phosphate. , One or more first materials selected from cordierite, silicon carbide, silicon nitride, sialon, alumina, zirconia, mullite, zircon, aluminum nitride, calcium silicate, B ₄ C. A position measuring mirror comprising a composite material obtained by combining at least one second material selected from C.
(5) In the above (1) to (4), the difference between the base material and the joining material in the average thermal expansion coefficient at 20 to 30 ° C. is ± 0.1 × 10. ^-6 A mirror for position measurement, which is within / ° C.
(6) A member that is provided on a sample stage that holds the sample horizontally and is used as a position measuring mirror that reflects reflected light and obtains reflected light for position measurement. The member is made of low-thermal-expansion ceramic and has at least one groove. The first member and the second member having the following structure are joined by a joining material made of a low thermal expansion ceramic having a lower melting temperature than the low thermal expansion ceramic constituting the first member and the second member so that the groove becomes a hollow portion. A mirror member, wherein the surface on which the film is formed has a surface roughness Ra of 10 nm or less.
(7) A member that is provided on a sample stage that holds the sample horizontally and is used as a position measuring mirror that reflects reflected light and obtains reflected light for position measurement, and is a porous second member made of low thermal expansion ceramics. The first member and the dense second member having a surface on which the reflective film is formed are joined with a joining material made of a low thermal expansion ceramic having a lower melting temperature than the low thermal expansion ceramic constituting the first member and the reflective film. A mirror member having a surface roughness Ra of 10 nm or less.
(8) In the above (6) and (7), the average thermal expansion coefficient of the mirror body at 20 to 30 ° C. is −1 × 10. ^-6 ~ 1 × 10 ^-6 / ° C.
(9) In the above (6) to (8), the low thermal expansion ceramics constituting the first and second members and the low thermal expansion ceramics constituting the bonding material are all lithium aluminosilicate and potassium zirconium phosphate. , One or more first materials selected from cordierite, silicon carbide, silicon nitride, sialon, alumina, zirconia, mullite, zircon, aluminum nitride, calcium silicate, B ₄ C. A mirror member comprising a composite material obtained by compounding one or more second materials selected from C.
(10) In the above (6) to (9), the difference in average thermal expansion coefficient at 20 to 30 ° C. between the base material and the bonding material is ± 0.1 × 10 ^-6 / ° C or lower.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described.
FIG. 1 is a plan view showing a stage mechanism for an exposure apparatus on which a position measuring mirror of the present invention is mounted. The stage mechanism for an exposure apparatus includes a stage body 1 on which a semiconductor wafer 10 is placed, an X-direction motor 2 for moving the stage body 1 in the X direction, a Y-direction motor 3 for moving the stage body 1 in the Y direction, and a stage. A mirror 4 for X-direction position measurement which is fixed to an end of the main body 1 and extends in the Y-direction and has a prismatic shape, and is provided at an end of the stage main body 1 so as to be orthogonal to the X-direction position measurement mirror 4. The mirror 5 for measuring the Y-direction position, which has a prism shape, the laser interferometer 6 for measuring the X-direction position, which irradiates the mirror 4 for measuring the X-direction position, and the mirror 5 for measuring the Y-direction position. And a laser interferometer 7 for measuring a position in the Y direction which emits a laser beam.
[0014]
As shown in the side view of FIG. 2, the mirrors 4 and 5 for measuring the position in the X direction and the position in the Y direction are a mirror main body 11 and a reflection film formed on the surface of the mirror main body 11 to which the laser beam is irradiated. 12 are provided.
[0015]
In the first embodiment, the mirror main body 11 has the same low thermal expansion as the first member 13 having the groove 14 made of low thermal expansion ceramic, as shown in a partial cross-sectional perspective view of FIG. The second member 15 functioning as a lid for closing the groove 14 made of ceramics is joined with a joining material 16 made of low thermal expansion ceramics having a lower melting temperature than the low thermal expansion ceramics constituting them, The outer shape is prismatic and has a hollow portion inside. Further, as shown in a partial cross-sectional perspective view of FIG. 3B, a second member 15 'having a groove 14' is used instead of the second member 15 functioning as a lid, similarly to the first member. Thus, the grooves 14 and 14 'may constitute a hollow portion. In this example, the reflection layer 12 is formed on the surface of the first member 13, but the reflection layer may be formed on the surfaces of the second members 15, 15 '.
[0016]
By using a low thermal expansion ceramic having a lower melting temperature than the first member 13 and the second members 15 and 15 ′, which are the materials to be joined, as the joining material 16, the joining material 16 has a melting temperature lower than the melting temperature of the joining material 16 at the time of joining. By heating at a high temperature and lower than the melting temperature of the first member 13 and the second member 15, only the bonding material 16 is melted and the first member 13 and the second members 15, 15 'are separated. Can be joined. Thereby, a joined body having a hollow portion inside is formed, and the weight can be reduced by about 40% as compared with the case of a solid material.
[0017]
In this case, the groove 14 or the grooves 14, 14 'may be formed first and then joined to the first member 13, or the first member 13 and the second member 15', so that the processing of the groove is easy. The weight can be reduced without any difficulty. In addition, since the joining material 16 is a low thermal expansion ceramic, the thermal expansion coefficient can be substantially the same as that of the first and second members 13, 15, 15 ', and the measurement accuracy changes with time due to the thermal expansion difference. hard. In addition, the stress remaining in the joint is small, and the rigidity of the joint is high, so that the rigidity of the entire member is high. In addition, the strength of the joint itself is higher than that of glass, so that the joint strength is high.
[0018]
Further, in the second embodiment, the mirror main body 11 is made of a porous first member 23 made of low thermal expansion ceramics and a similar low thermal expansion ceramic as shown in a partial sectional perspective view of FIG. And a dense second member 24 having a surface on which the reflective film 12 is formed is joined with a joining material 25 made of low thermal expansion ceramics having a lower melting temperature than the low thermal expansion ceramics constituting them. , The outer shape is a prismatic shape.
[0019]
By using the low thermal expansion ceramic having a lower melting temperature than the first member 23 and the second member 24, which are the materials to be joined, as the joining material 25, the joining material 25 is higher than the melting temperature of the joining material 25 at the time of joining. By heating at a temperature lower than the melting temperature of the first member 23 and the second member 24, only the bonding material 25 is melted and the first member 23 and the second member 24 can be bonded. By the presence of the porous first member 23, the weight can be reduced by about 30% as compared with the case of a solid material.
[0020]
In this case, although good surface roughness cannot be obtained with the porous material, good mirror characteristics can be obtained because the dense second member 24 is joined to make the surface a reflective surface. Further, since the processing of the groove is unnecessary, the weight can be reduced without any difficulty. In addition, since the joining material 25 is a low thermal expansion ceramic, the thermal expansion coefficient can be substantially the same as that of the first and second members 23 and 24, and the measurement accuracy due to the difference in thermal expansion hardly changes with time. In addition, the stress remaining in the joint is small, and the rigidity of the joint is high, so that the rigidity of the entire member is high. In addition, the strength of the joint itself is higher than that of glass, so that the joint strength is high.
[0021]
Here, in both the first and second embodiments, the average thermal expansion coefficient of the mirror body 11 at 20 to 30 ° C. is −1 × 10 ^-6 ~ 1 × 10 ^-6 / ° C. Thermal expansion coefficient is 1 × 10 ^-6 / ° C or -1 × 10 ^-6 If the temperature is lower than / ° C, a slight change in the ambient temperature causes deformation of 100 nm or more, resulting in a decrease in position measurement accuracy. In both the first and second embodiments, the difference in the average thermal expansion coefficient between the first and second members and the bonding material at 20 to 30 ° C. is ± 0.1 × 10 ^-6 / ° C is preferred. If the difference in the coefficient of thermal expansion exceeds this range, the internal stress accumulates during the cooling process after the heat treatment for joining, and the strength may be reduced.
[0022]
The first members 13, 23 and the second members 15, 15 ', 24, which are the materials to be joined, and the low thermal expansion ceramics constituting the joining materials 16, 25 are all composite materials made of two or more materials. Preferably, there is. By changing the mixing ratio of the materials constituting the material to be joined, it is possible to cope with various required thermal expansions, and the joining material has a thermal expansion suitable for the material to be joined. Therefore, it is possible to easily obtain the mirror main body 11 having a desired low thermal expansion, and it is possible to apply the mirror body 11 with a high degree of freedom.
[0023]
The composite materials forming the first and second members 13 and 23 and the second members 15, 15 ′ and 24 to be joined and the joining materials 16 and 25 include lithium aluminosilicate, potassium zirconium phosphate, cordierite At least one first material selected from the group consisting of silicon carbide, silicon nitride, sialon, alumina, zirconia, mullite, zircon, aluminum nitride, calcium silicate, and B ₄ Those composed of at least one second material selected from C are preferable. Of these constituent materials, the first material has a very low thermal expansion, and the second material has a higher thermal expansion coefficient than the first material but a higher Young's modulus. And a material having both high rigidity.
[0024]
As the first material, β-eucryptite or spodumene, which is lithium aluminosilicate, is preferable. Among them, β-eucryptite exhibits a negative thermal expansion. Therefore, by combining it with a second material exhibiting a positive thermal expansion, it is possible to obtain an extremely low thermal expansion coefficient. It is possible to adjust the thermal expansion coefficient in a wide range from minus to plus by adjusting. In addition, lithium aluminosilicate represented by β-eucryptite and spojumen forms a solid solution with other components such as Ca, Mg, Fe, K, Ti, and Zn. In the present invention, such a solid solution is also applied. It is possible.
[0025]
On the other hand, the second material is set so that the melting temperature of the joining materials 16 and 25 is lower than the melting temperature of the first members 13 and 23 and the second members 15, 15 ′ and 24 that are the materials to be joined. It is appropriately selected from materials.
[0026]
Specifically, the composite material constituting the bonding materials 16 and 25 is preferably a material composed of β-eucryptite and silicon nitride. This composite material has low thermal expansion, high rigidity, and a relatively low melting temperature of 1300 to 1360 ° C. In the present invention, since the joining material can join a base material made of a low thermal expansion ceramic that sinters at a temperature higher than its melting temperature, the joining material that melts at a relatively low temperature has an applicable range. wide. Further, as described above, β-eucryptite has a negative coefficient of thermal expansion, and silicon nitride has a positive coefficient of thermal expansion. Until the thermal expansion coefficient can be changed arbitrarily, therefore, by appropriately selecting these compounding ratios according to the thermal expansion coefficient of the material to be joined, the base material of any material Good joining can be achieved without generating stress.
[0027]
It should be noted that if a substantial chemical reaction does not occur in the composite materials constituting the first members 13 and 23 and the second members 15, 15 ′ and 24 as the materials to be joined and the joining materials 16 and 25, It is also possible to use a plurality of materials in combination as the first material. Similarly, the second material can be used in combination of a plurality of materials as long as no substantial chemical reaction occurs.
[0028]
As described above, when the first members 13 and 23 and the second members 15, 15 ′ and 24, which are the materials to be joined, and the low thermal expansion ceramics constituting the joining materials 16 and 25 are all composite materials, It is preferable that at least one of the constituent materials of the composite material forming the bonding material is the same as the constituent material of the composite material forming the bonding material. Thereby, the common constituent material can be easily diffused and firmly joined, and the joining surface is clean.
[0029]
When the first members 13, 23 and the second members 15, 15 ', 24 and the joining materials 16, 25, which are to be joined, are all composite materials, the specific material combination is the melting temperature of the joining material. Is arbitrary as long as it is a low thermal expansion ceramic lower than the melting temperature of the material to be joined, and various combinations can be adopted. Among them, it is preferable to use a composite material of β-eucryptite and silicon carbide as the material to be joined and use the composite material of β-eucryptite and silicon nitride as the joining material. The body to be joined made of a composite material of β-eucryptite and silicon carbide has a melting temperature of 1370 to 1430 ° C., which is the melting temperature of the composite material of β-eucryptite and silicon nitride constituting the joining material. The temperature is higher than 1300 to 1360 ° C, and there is no possibility that the base material of the material to be joined is melted when the joining material is melted and joined. Moreover, since β-eucryptite is commonly contained in the base material and the joining material, the joining is strong, and all of them have a low thermal expansion, and have approximately the same coefficient of thermal expansion by adjusting the composition. And both the base material and the joining material have high rigidity. In this case, the composition of the base material is 50 to 95% by mass of β-eucryptite and 5 to 50% by mass of silicon carbide, and the composition of the bonding material is 40 to 85% by mass of β-eucryptite and silicon nitride. It is preferably 15 to 60% by mass.
[0030]
It is not always necessary that both the first members 13 and 23 and the second members 15 and 24, which are the materials to be joined, and the joining materials 16 and 25 are composite materials, and only the joining materials 16 and 25 are composite materials. It may be. By using a composite material as the low-thermal-expansion ceramic constituting the joining materials 16 and 25, the composition of the constituting materials can be changed so as to have a thermal expansion suitable for the material to be joined, and the degree of freedom of application is extremely increased. be able to.
[0031]
The surface roughness of the surface of the mirror body 11 on which the reflection film 12 is formed is set to 10 nm or less in Ra. Thereby, a high reflectance is obtained after the formation of the reflective film 12. Preferably it is 6 nm or less. For example, when the incident light is a laser having a wavelength of 633 nm, a high reflectance of 80% or more is obtained when the surface roughness Ra is 10 nm, and a high reflectance of 85% or more is obtained when the surface roughness Ra is 6 nm.
[0032]
Such a mirror main body 11 is obtained by kneading a bonding material powder with an appropriate binder to form a paste having a viscous property, and through this paste, the first members 13, 23 and the second members 15, 15 ', 24 The first members 13, 23 and the second members 15, 15 ', 24 are heat-treated at a temperature at which the bonding materials 16, 25 are melted but the first members 13, 23 and the second members 15, 15', 24 are not melted. As a result, the joining materials 16 and 25 are melted, and a part thereof is diffused into the first members 13 and 23 and / or the second members 15, 15 ′ and 24 to join these members.
[0033]
As the heat treatment atmosphere at this time, an air atmosphere can be used as long as all the materials are oxide-based, but a non-oxidation atmosphere can be used when non-oxide-based materials are included. preferable.
[0034]
The dense first member 13 and the second member 15, 15 ′ of the first embodiment and the dense second member 24 of the second embodiment are made of raw material powder, for example, low thermal expansion. The ceramic powder and the high Young's modulus ceramic powder are mixed at a predetermined ratio, and the mixed powder is formed into a compact by press molding or the like, fired at a predetermined temperature to form a sintered body, and processed. As for the firing conditions, in the case of an oxide-based material or a material similar thereto, firing may be performed in an oxidizing atmosphere, but when non-oxide ceramics are contained, firing is preferably performed in a non-oxidizing atmosphere. After sintering, the mirror surface is mirror-finished so that the surface roughness of the reflection surface on which the reflection film 12 is formed is 10 nm or less in Ra as described above, and the mirror surface is obtained.
[0035]
In addition, the porous first member 23 in the second embodiment may be in any form, but a main form is a foam or filter. When forming a foam-like porous body, a binder capable of imparting thixotropic properties such as carboxymethylcellulose or hydroxyethylcellulose and having a shape-retaining ability is added to a slurry pulverized and mixed by a ball mill, and the slurry is pulverized soft urethane. It is impregnated into a foam such as a foam, dried and fired. As a result, a porous body is formed in which the portion where the foam has disappeared becomes a pore. In the case of forming a filter-like porous body, a ceramic slurry is mixed with an organic substance that decomposes by heating as particles serving as pore bases, for example, resin beads, carbon beads, and the like, and an appropriate method such as extrusion, casting, and pressing is performed. And fired. As a result, a porous body is formed in which the portions where the particles have disappeared become pores.
[0036]
The reflection film 12 is formed to a thickness of about 0.1 to 1 nm on a mirror surface which has been mirror-finished so that the surface roughness of the mirror main body 11 is 10 nm or less in Ra. Specifically, after vapor deposition using a metal film of Al, Ag, Pt or the like as a base, SiO ₂ , TiO ₂ A dielectric film and a metal film are alternately deposited to form a reflective film 12 having a multilayer structure. For example, Al-SiO ₂ In the case of a laminated film, the reflectance of 80% or more is obtained at a laser frequency of 633 nm when the surface roughness Ra of the mirror body 11 is 10 nm or less. Also, Al-Ti-TiO ₂ By forming the reflection-enhancing film composed of the laminated film as the reflection film 12, Al-SiO in a specific frequency range is obtained. ₂ Compared with a normal reflective film such as a laminated film, an improvement in reflectance of about 5% is expected, and an extremely high reflectance of about 85% or more can be obtained.
[0037]
The surface accuracy of the reflection film formed on the mirror main body 11 made of the composite material can be λ / 20 in flatness. Here, the flatness is generally calculated from interference fringes caused by light having a wavelength of visible light of 360 to 700 nm, and a laser interferometer used for such flatness evaluation uses a He-Ne laser as a laser source. (Λ = 633 nm), and the flatness is indicated based on the wavelength λ = 633 nm. Usually, the flatness required as a reflecting mirror is about λ / 4 to λ / 10, and λ / 20 is extremely high.
[0038]
As described above, the mirror for position measurement is completed by forming the reflection film 12 on the mirror main body 11 by vapor deposition or the like. However, after sintering, the sintered body is processed to finish the reflection surface to 10 nm or less. It may be formed as a mirror member, and a reflective film may be deposited on the user side.
[0039]
【Example】
Examples of the present invention will be described below.
(Example 1)
The β-eucryptite powder and the silicon carbide powder were mixed with No. Pot mills were mixed in the ratios shown in 1 to 3 and dried to prepare a raw material mixed powder. This mixed powder was subjected to CIP molding under a pressure of 120 MPa to produce two types of molded products (A) 40 mm × 35 mm × 620 mm and (B) 40 mm × 11 mm × 620 mm. It was hollowed out to leave 8mm. After degreasing each compact at 500 ° C., the compact was fired at 1370 ° C. in a nitrogen atmosphere to obtain a ceramic sintered body in which β-eucryptite and silicon carbide were combined. The obtained sintered body was machine-finished to (A) 32 mm × 27 mm × 500 mm and (B) 32 mm × 8 mm × 500 mm.
[0040]
Next, β-eucryptite and silicon nitride were mixed in a pot mill at the ratio shown in Table 1 and dried to prepare a mixed powder for a bonding material. This mixed powder was mixed with a 15% α-terpineol solution of ethyl cellulose so as to have an inorganic content of 30 vol%, and made into a paste using a three-roll, to prepare a bonding material paste.
[0041]
The bonding material paste was printed to a thickness of 30 μm using a screen mask on the end of the wall surface of the molded product of (A) and the corresponding portion of one surface of the molded product of (B) to obtain a bonding material. After degreased at 500 ° C, the printed surfaces are adhered to each other to 1.5 g / mm ² Was applied. Subsequently, a heat treatment was performed at a temperature of 1300 to 1350 ° C. in a nitrogen atmosphere to melt the joining material to obtain a joined body in which the joining material was interposed between the sintered bodies (A) and (B).
[0042]
Prior to joining, one long surface of the sintered body (A) was mirror-finished to have a surface roughness Ra of 10 nm or less. Therefore, the joined body thus obtained functions as a mirror body.
[0043]
A metal film and a dielectric thin film were alternately deposited on the mirror-finished surface of the mirror body to form a reflection film. Al-SiO as reflective film ₂ A laminated film was used.
[0044]
Separately from this, a test piece of 4 mm × 4 mm × 12 mm was cut out from the sintered body, and the displacement of the test piece was measured at 20 to 30 ° C. using a laser interference thermal expansion measuring device (LIX-1 manufactured by ULVAC-RIKO). Was measured to determine the coefficient of thermal expansion. As for the joining material, sintered bodies having the same composition were prepared, and the thermal expansion coefficients were measured in the same manner. These results are shown in Table 1.
[0045]
Further, the surface roughness of the mirror-finished surface was measured by a stylus type surface roughness measuring machine TALYSURF (manufactured by Taylor-Hobson). Further, the reflectance after the formation of the reflective film was obtained by irradiating He-Ne laser light having a wavelength of 633 nm perpendicularly to the mirror surface, measuring the intensity of reflected light and the surface accuracy, and measuring the change over time in the surface accuracy. Furthermore, the weight of the mirror was measured. These results are shown in Table 2.
[0046]
(Example 2)
β-eucryptite powder: 56 parts by mass (D50 = 5 μm), silicon carbide powder: 18 parts by mass (D50 = 0.7 μm) were pulverized and mixed with a water medium in a ball mill, and then resin (spherical acrylic beads): 24 2 parts by mass of a binder and 2 parts by mass of a binder (polyvinyl alcohol) were added and mixed to form a slurry, which was then granulated by spray drying. The granules are subjected to CIP molding at a pressure of 120 MPa, processed to produce a molded body of 40 mm × 35 mm × 620 mm, degreased at 500 ° C., baked at 1350 ° C. in a nitrogen atmosphere, and β-eucrypt A porous ceramic sintered body having a porosity of 40% in which tight and silicon carbide were combined was obtained. The obtained sintered body was subjected to a mechanical finishing process of 32 mm × 27 mm × 500 mm.
[0047]
On the other hand, in the same manner as in Example 1, a dense sintered body of 32 mm × 8 mm × 500 mm composed of β-eucryptite and silicon carbide was obtained, and the same bonding material and the same bonding as in Example 1 were obtained. The porous sintered body and the dense sintered body were joined by a method to obtain a joined body.
[0048]
Prior to joining, one long surface of the dense sintered body was mirror-finished to have a surface roughness Ra of 10 nm or less. Therefore, the joined body thus obtained functions as a mirror body.
[0049]
A metal film and a dielectric thin film were alternately deposited on the mirror-finished surface of the mirror body to form a reflection film. Al-SiO as reflective film ₂ A laminated film was used.
[0050]
Separately from this, a test piece of 4 mm × 4 mm × 12 mm was cut out from the sintered body, and the displacement of the test piece was measured at 20 to 30 ° C. using a laser interference thermal expansion measuring device (LIX-1 manufactured by ULVAC-RIKO). Was measured to determine the coefficient of thermal expansion. As for the joining material, sintered bodies having the same composition were prepared, and the thermal expansion coefficients were measured in the same manner. These results are shown in Table 1.
[0051]
Further, the surface roughness of the mirror-finished surface was measured by a stylus type surface roughness measuring machine TALYSURF (manufactured by Taylor-Hobson). Further, the reflectance after the formation of the reflective film was obtained by irradiating He-Ne laser light having a wavelength of 633 nm perpendicularly to the mirror surface, measuring the intensity of reflected light and the surface accuracy, and measuring the change over time in the surface accuracy. Furthermore, the weight of the mirror was measured. These results are shown in Table 2.
[0052]
(Comparative example)
As shown in Table 1, a solid composite material (No. 5) sintered under the same composition and under the same conditions as in the sintered body of Example 1 was a bonded body similar to that of Example 1, but was bonded. A material using glass as a material (No. 6), a bonded body similar to that of Example 2, but using glass as a bonding material (No. 7), a bonded body similar to Example 1, A mirror body having a large reflective surface roughness (No. 8) and a mirror body manufactured was evaluated in the same manner. The results are also shown in Tables 1 and 2.
[0053]
As shown in Tables 1 and 2, Examples 1 and 2 were Nos. 1 and 2 of Comparative Examples, which were solid materials of the same material. 5 can be reduced by about 40% and 30%, respectively, and each has a thermal expansion coefficient of 1.0 × 10 ^-6 / ° C. or less, and the surface roughness Ra is 10 nm or less, and the reflectivity of the reflective film shows a sufficient value of 80% or more, and the surface accuracy λ / 20 was realized. Also, there was almost no change in surface accuracy with time.
[0054]
In contrast, the same composite material but a solid No. No. 5 has a large weight as described above, and No. 5 bonded using glass. In Nos. 6 and 7, the surface accuracy was poor, and the surface accuracy also changed over time. In addition, No. 1 in which the surface roughness of the reflection surface is large. In No. 8, the result was a low reflectance of 70%.
[0055]
[Table 1]

[0056]
[Table 2]

[0057]
【The invention's effect】
As described above, according to the present invention, the first member and the second member which are made of low thermal expansion ceramics and have a groove at least on one side are formed so that the grooves are hollow so that the first member and the second member are hollow. The mirror body is formed by joining with a joining material made of low thermal expansion ceramics having a lower melting temperature than that of expanded ceramics, or the surface on which the porous first member made of low thermal expansion ceramics and the reflection film are formed is formed. The second member having a dense structure is joined with a joining material made of low-thermal-expansion ceramic having a lower melting temperature than the low-thermal-expansion ceramic constituting them to form a mirror main body, and a surface on which the reflection film is formed is formed. Since the surface roughness is set to 10 nm or less in Ra, it is possible to reduce the weight while ensuring sufficient mirror characteristics without causing difficulty or deterioration of characteristics. Can be can be, obtain a high measurement accuracy position measurement mirror.
[Brief description of the drawings]
FIG. 1 is a plan view showing a stage mechanism for an exposure apparatus on which a position measuring mirror of the present invention is mounted.
FIG. 2 is a side view showing the position measuring mirror of the present invention.
FIG. 3 is a partial sectional perspective view showing a position measuring mirror according to the first embodiment of the present invention.
FIG. 4 is a partial sectional perspective view showing a position measuring mirror according to a second embodiment of the present invention.
[Explanation of symbols]
1: Stage
2: X direction motor
3: Y-direction motor
4,5; mirror
6; Laser interferometer for X-direction position measurement
7; Laser interferometer for Y-direction position measurement
10; semiconductor wafer
11; mirror body
12; reflective film
13, 23; first member
15, 15 ', 24; second member
16, 25; bonding material

Claims (10)

A position measurement mirror that is provided on a sample stage that holds the sample horizontally and obtains reflected light for position measurement by reflecting irradiation light,
Having a mirror body and a reflective film provided on the surface thereof,
The mirror body is made of low thermal expansion ceramic and has a first member and a second member having a groove in at least one of the first member and the second member so that the groove has a hollow portion, and has a melting temperature lower than that of the low thermal expansion ceramic constituting these members. A position measuring mirror which is bonded with a bonding material made of low-low-thermal-expansion ceramic and has a surface roughness Ra of 10 nm or less on a surface on which the reflection film is formed. A position measurement mirror that is provided on a sample stage that holds the sample horizontally and obtains reflected light for position measurement by reflecting irradiation light,
Having a mirror body and a reflective film provided on the surface thereof,
The mirror main body is made of a low-thermal-expansion ceramic, and has a porous first member and a dense second member having a surface on which the reflective film is formed. A position measuring mirror which is bonded with a bonding material made of low-low-thermal-expansion ceramic and has a surface roughness Ra of 10 nm or less on a surface on which the reflection film is formed. The position measuring mirror according to claim 1, wherein an average coefficient of thermal expansion of the mirror body at 20 to 30 ° C. is −1 × 10 ⁻⁶ to 1 × 10 ⁻⁶ / ° C. 4. . The low thermal expansion ceramics forming the first and second members and the low thermal expansion ceramics forming the bonding material are each at least one of a first aluminosilicate, a potassium zirconium phosphate, and a cordierite. And a second material selected from the group consisting of silicon carbide, silicon nitride, sialon, alumina, zirconia, mullite, zircon, aluminum nitride, calcium silicate, and B ₄ C. The position measuring mirror according to any one of claims 1 to 3, wherein the mirror is configured. The method according to any one of claims 1 to 4, wherein a difference in an average thermal expansion coefficient between 20 ° C and 30 ° C between the base material and the joining material is within ± 0.1 × 10 ⁻⁶ / ° C. 2. The position measuring mirror according to claim 1. A member used for a position measurement mirror that is provided on a sample stage that holds the sample horizontally and reflects the irradiation light to obtain reflected light for position measurement,
The first member and the second member which are made of low thermal expansion ceramic and have a groove at least on one side are made of a low thermal expansion ceramic having a lower melting temperature than the low thermal expansion ceramic constituting these so that the groove becomes a hollow portion. A mirror member formed by bonding with a bonding material having a surface roughness Ra of 10 nm or less on a surface on which a reflective film is formed. A member used for a position measurement mirror that is provided on a sample stage that holds the sample horizontally and reflects the irradiation light to obtain reflected light for position measurement,
The porous first member made of low thermal expansion ceramics and the dense second member having a surface on which the reflection film is formed are made of low thermal expansion ceramics having a lower melting temperature than the low thermal expansion ceramics forming these members. A mirror member which is bonded with a bonding material and has a surface roughness Ra of 10 nm or less on a surface on which a reflective film is formed. The mirror member according to claim 6, wherein an average coefficient of thermal expansion of the mirror body at 20 to 30 ° C. is −1 × 10 ⁻⁶ to 1 × 10 ⁻⁶ / ° C. 9. The low-thermal-expansion ceramics constituting the first and second members and the low-thermal-expansion ceramic constituting the bonding material are each at least one of a first aluminosilicate, a potassium zirconium phosphate, and a cordierite. And a second material selected from the group consisting of silicon carbide, silicon nitride, sialon, alumina, zirconia, mullite, zircon, aluminum nitride, calcium silicate, and B ₄ C. The mirror member according to any one of claims 6 to 8, wherein the mirror member is configured. The difference between the average thermal expansion coefficient at 20 to 30 ° C between the base material and the joining material is within ± 0.1 × 10 ⁻⁶ / ° C. 2. The mirror member according to claim 1.

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