JP4482891B2 - Imaging optical system, exposure apparatus, and exposure method - Google Patents

Description

  The present invention relates to an imaging optical system, an exposure apparatus, and an exposure method, and more particularly, to a high-resolution projection optical system suitable for an exposure apparatus used when manufacturing a semiconductor element, a liquid crystal display element, or the like in a photolithography process. Is.

  An exposure apparatus that exposes a pattern image of a mask (or reticle) onto a wafer (or glass plate or the like) coated with a photoresist or the like via a projection optical system in a photolithography process for manufacturing a semiconductor element or the like. Is used. As the degree of integration of semiconductor elements and the like increases, the resolving power (resolution) required for the projection optical system of the exposure apparatus is increasing.

  Therefore, in order to satisfy the requirement for the resolution of the projection optical system, it is necessary to shorten the wavelength λ of the illumination light (exposure light) and increase the image-side numerical aperture NA of the projection optical system. Specifically, the resolution of the projection optical system is represented by k · λ / NA (k is a process coefficient). In addition, the image-side numerical aperture NA is defined such that the refractive index of a medium (usually a gas such as air) between the projection optical system and a photosensitive substrate (such as a wafer) is n, and the maximum incident angle on the photosensitive substrate is θ. Then, it is expressed by n · sin θ.

  In this case, if the maximum incident angle θ is increased to increase the image-side numerical aperture, the incident angle to the photosensitive substrate and the exit angle from the projection optical system increase, and the reflection loss on the optical surface increases. Thus, a large effective image-side numerical aperture cannot be ensured. Therefore, a technique for increasing the image-side numerical aperture by filling a medium such as a liquid having a high refractive index in an optical path between a projection optical system as an imaging optical system and a photosensitive substrate is known.

  In general, the refractive index fluctuation of a liquid due to a temperature change is larger than the refractive index fluctuation of a gas such as air. For this reason, in order to minimize the aberration variation of the projection optical system during exposure without being substantially affected by the change in the refractive index of the liquid due to temperature changes, it is necessary to increase the thickness of the liquid layer and thus the projection optics. The working distance on the image side of the system (the distance between the optical surface closest to the image side and the image plane) cannot be set large.

  On the other hand, the irradiated light energy is relatively large at the boundary lens that is disposed closest to the image side in the projection optical system and contacts the liquid. As a result, when the boundary lens disposed at a relatively large position of light energy is made of quartz, local refractive index change due to volume shrinkage, that is, compaction is likely to occur, and the imaging performance of the projection optical system is deteriorated due to the effect of compaction. there is a possibility.

  Therefore, in order to avoid the deterioration of the imaging performance of the projection optical system due to compaction, a fluoride material having a sufficiently large transmittance for light in the extreme ultraviolet region, in particular, a material having excellent homogeneity has been developed. It is conceivable to form a boundary lens using fluorite. However, it is known that fluoride has a property of being dissolved in water. For example, when a boundary lens is formed using fluorite and pure water is used as an immersion liquid, the optical surface of the boundary lens is pure water (immersion). Therefore, the imaging performance of the projection optical system cannot be satisfactorily maintained over a long period of time.

  The present invention ensures good image formation without substantial influence of compaction or damage due to immersion liquid while ensuring a large effective image-side numerical aperture by interposing a liquid in the optical path to the image plane. An object of the present invention is to provide an imaging optical system capable of maintaining the performance over a long period of time.

  In addition, the present invention uses an imaging optical system that can maintain a good imaging performance over a long period of time while ensuring a large effective image-side numerical aperture. An object is to provide an exposure apparatus and an exposure method that can be performed stably over a period of time.

In order to achieve the above object, in the first embodiment of the present invention, in an imaging optical system that optically conjugates the first surface and the second surface,
When the refractive index of the atmosphere in the optical path of the imaging optical system is 1, the optical path between the imaging optical system and the second surface is filled with a liquid having a refractive index greater than 1.1.
On the second surface side in the imaging optical system, a joint formed by joining a first optical member formed of a first optical material and in contact with the liquid, and a second optical member formed of the second optical material. An optical member is arranged,
When the thickness of the first optical member is TA and the maximum image height on the second surface is IH,
0.1 <TA / IH <1.1
An imaging optical system characterized by satisfying the following conditions is provided.

In the second embodiment of the present invention, in the imaging optical system that optically conjugates the first surface and the second surface,
When the refractive index of the atmosphere in the optical path of the imaging optical system is 1, the optical path between the imaging optical system and the second surface is filled with a liquid having a refractive index greater than 1.1.
On the most second surface side in the imaging optical system, the first optical member formed by the first optical material and in contact with the liquid is joined to the second optical member formed by the second optical material. An imaging optical system is provided in which a bonding optical member is disposed.

  According to a third aspect of the present invention, there is provided an imaging optical system according to the first or second aspect for forming an image of a pattern set on the first surface on a photosensitive substrate set on the second surface. An exposure apparatus is provided.

  In the fourth aspect of the present invention, an illumination process for illuminating the mask set on the first surface, and an image of the pattern formed on the mask via the imaging optical system of the first or second form And an exposure step of performing projection exposure on a photosensitive substrate set on the second surface.

  In the fifth aspect of the present invention, a step of supplying a predetermined pattern, and an image of the pattern is formed on the photosensitive substrate set on the second surface via the imaging optical system of the first aspect or the second aspect. And a device manufacturing method including an exposure step of performing projection exposure.

  In the present invention, in the imaging optical system that optically conjugates the first surface and the second surface, a refractive index greater than 1.1 is provided in the optical path between the imaging optical system and the second surface. Increasing the numerical aperture on the second surface side of the imaging optical system is achieved by interposing the liquid (immersion liquid) that is included. Further, the boundary lens that is arranged closest to the second surface side and contacts the liquid is formed by joining a first optical member that is formed of, for example, synthetic quartz and that is in contact with the liquid, and a second optical member that is formed of, for example, fluorite. It is configured as a bonded optical member. With this configuration, it is possible to prevent the imaging performance from being deteriorated due to the influence of compaction in the boundary lens, and to prevent the imaging performance from being deteriorated due to damage to the optical surface of the boundary lens due to the influence of the immersion liquid (liquid). .

  Thus, in the present invention, the liquid is interposed in the optical path between the second surface and a large effective second surface side numerical aperture is ensured, while being substantially affected by the influence of compaction and immersion. An imaging optical system that can maintain good imaging performance over a long period of time can be realized. As a result, in the exposure apparatus and exposure method using the imaging optical system of the present invention, high-resolution projection exposure can be stably performed over a long period of time, and a good device can be manufactured.

It is a figure which shows roughly the influence which the compaction of the 1st optical member which is formed of synthetic quartz in the projection optical system according to a typical design and contacts the immersion liquid has on the imaging performance of the projection optical system. It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment of this invention. It is a figure which shows roughly the structure from the boundary lens in this embodiment to a wafer. It is a figure which shows a mode that overcoating was formed in the side surface of a 1st optical member and a 2nd optical member. It is a figure which shows a mode that a boundary lens is hold | maintained at the lens barrel via the 2nd optical member. It is a flowchart of the method at the time of obtaining the semiconductor device as a microdevice. It is a flowchart of the method at the time of obtaining the liquid crystal display element as a microdevice.

  In the present invention, an image is formed by interposing a liquid having a refractive index greater than 1.1 in the optical path between the imaging optical system and the second surface on which the photosensitive substrate is typically disposed. The numerical aperture on the second surface side of the optical system is increased. By the way, “Resolution Enhancement of 157-nm Lithography by Liquid Immersion” announced by M.Switkes and M.Rothschild at “Massachusetts Institute of Technology” at “SPIE2002 Microlithography” As liquids having the required transmittance, Fluorinert (Perfluoropolyethers: trade name of 3M USA) and Deionized Water are listed as candidates.

  In the imaging optical system (projection optical system) of the present invention, the boundary lens disposed closest to the image side (second surface side) and in contact with the liquid (immersion liquid) is made of, for example, synthetic quartz (first optical material). The first optical member that is formed and in contact with the liquid and a second optical member that is formed of, for example, fluorite (second optical material) are configured as a bonded optical member. Here, the first optical member and the second optical member are joined by, for example, optical contact (optical welding). Optical contact is a technology that processes the surfaces of two optical members with the same shape with high accuracy, and attaches the two optical members by attractive force between molecules without using an adhesive by bringing the surfaces close to each other. It is.

In the present invention, in addition to the above-described configuration, the first optical member formed of, for example, synthetic quartz and in contact with the liquid satisfies the following conditional expression (1). In conditional expression (1), TA is the thickness of the first optical member (the dimension of the first optical member along the optical axis), and IH is the maximum image height on the image plane (second surface).
0.1 <TA / IH <1.1 (1)

  FIG. 1 is a diagram schematically showing the influence of the compaction of a first optical member formed of synthetic quartz in contact with an immersion liquid on the imaging performance of a projection optical system according to a typical design. In FIG. 1, the horizontal axis represents TA / IH corresponding to the conditional expression (1), and the vertical axis represents a wavefront aberration change amount (mλRMS) as an aberration deterioration amount expected after five years. In the unit mλRMS on the vertical axis, λ represents the wavelength of light, and RMS (root mean square) represents the root mean square (or root mean square).

  In the typical design example used to obtain FIG. 1, the light used is ArF excimer laser light (λ = 193 nm), the immersion liquid is pure water, and the image-side numerical aperture is 1.0. The maximum image height is 13.5 mm. Referring to FIG. 1, when the upper limit value of conditional expression (1) is exceeded, the amount of aberration deterioration expected after five years becomes too large to satisfy the optical performance required over a long period, that is, good It can be seen that excellent imaging performance cannot be maintained over a long period of time.

  On the other hand, if the lower limit of conditional expression (1) is not reached, the thickness TA of the first optical member that is formed of, for example, synthetic quartz and is in contact with the immersion liquid becomes too small, and processing with sufficient surface accuracy necessary for optical contact is performed. It can no longer be applied. Note that it is more preferable to set the upper limit value of the conditional expression (1) to 0.7, because even if the irradiation energy is increased, the influence of compaction can be suppressed and higher throughput and higher resolution can be realized. Further, it is more preferable to set the lower limit value of the conditional expression (1) to 0.14, because the processing surface accuracy of the first optical member can be improved and higher resolution can be realized.

  As described above, in the imaging optical system (projection optical system) of the present invention, compaction does not substantially occur in the second optical member formed of, for example, fluorite. On the other hand, compaction is likely to occur in the first optical member formed of, for example, synthetic quartz and in contact with the immersion liquid. However, since the thickness TA of the first optical member is set sufficiently small according to the conditional expression (1), The influence of compaction in one optical member can be suppressed small. As a result, it is possible to suppress degradation of the imaging performance of the imaging optical system (projection optical system) due to the influence of compaction in the boundary lens.

  However, the temperature of synthetic quartz is likely to rise due to light irradiation, and when the heat of the first optical member is transmitted to the liquid, the temperature of the liquid rises and the refractive index fluctuates, resulting in the formation of an imaging optical system (projection optical system). Image performance will be reduced. However, in the present invention, since the thickness TA of the first optical member is set sufficiently small according to the conditional expression (1), even if the temperature of the first optical member rises due to light irradiation, the heat is, for example, It is easy to be transmitted to a lens barrel or the like through the second optical member made of fluorite having a relatively high thermal conductivity. As a result, heat transmitted from the first optical member to the liquid can be suppressed to a low level, and as a result, a decrease in the imaging performance of the imaging optical system (projection optical system) due to a change in the refractive index of the liquid can be suppressed to a low level.

  Further, in the present invention, for example, a synthetic quartz that does not substantially dissolve in pure water is formed between the second optical member formed of fluorite that is easily dissolved in pure water and a liquid such as pure water. The first optical member is interposed in close contact. Therefore, the optical surface of the second optical member is not damaged by the influence of pure water, and the optical surface of the boundary lens is not damaged by the influence of pure water, and the imaging optical system (projection optical system). The imaging performance can be satisfactorily maintained over a long period of time. That is, according to the present invention, a liquid is interposed in the optical path between the image plane and a large effective image-side numerical aperture is ensured, while being substantially free from the influence of compaction and damage due to immersion liquid. An imaging optical system (projection optical system) that can maintain the imaging performance for a long period of time can be realized.

  In the present invention, in order to increase the numerical aperture on the second surface side (image side) of the imaging optical system (projection optical system), the object-side (first surface side) optical surface of the second optical member is provided. It is preferable that the convex surface is directed to the object side. Moreover, in order to implement | achieve a favorable optical contact, it is preferable that the joint surface of a 1st optical member and a 2nd optical member is planar shape. In order to improve the resolution (resolution) of the imaging optical system (projection optical system), the wavelength of the light used is preferably 300 nm or less. The second optical material forming the second optical member is preferably a fluoride (for example, fluorite) in order to avoid generation of compaction.

  Further, when the first optical member is soiled due to the influence of the photosensitive material dissolved in the immersion liquid or when the first optical member is eluted, it is necessary to replace the first optical member. In the method, there is an advantage that the mechanism for holding the first optical member in an exchangeable manner can be simplified, and this advantage is obtained by the first optical material forming the first optical member and the second optical material forming the second optical member. Even the same type of material exists.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 2 is a drawing schematically showing a configuration of the exposure apparatus according to the embodiment of the present invention. FIG. 3 is a diagram schematically showing a configuration from the boundary lens to the wafer in the present embodiment. In FIG. 2, the Z axis is parallel to the optical axis AX of the projection optical system PL, the Y axis is parallel to the paper surface of FIG. 2 in the plane perpendicular to the optical axis AX, and the X axis is perpendicular to the paper surface of FIG. Are set respectively.

  Referring to FIG. 2, the exposure apparatus of this embodiment includes, for example, an ArF excimer laser light source as a light source 100 for supplying illumination light in the ultraviolet region. The light emitted from the light source 100 illuminates the reticle R on which a predetermined pattern is formed in a superimposed manner via the illumination optical system IL. The optical path between the light source 100 and the illumination optical system IL is sealed with a casing (not shown), and the space from the light source 100 to the optical member on the most reticle side in the illumination optical system IL absorbs exposure light. It is replaced with an inert gas such as helium gas or nitrogen, which is a low-rate gas, or is kept in a substantially vacuum state.

  The reticle R is held parallel to the XY plane on the reticle stage RS via the reticle holder RH. A pattern to be transferred is formed on the reticle R, and a rectangular pattern region is illuminated. Reticle stage RS can be moved two-dimensionally along the reticle plane (ie, XY plane) by the action of a drive system (not shown), and its position coordinates are measured by interferometer RIF using reticle moving mirror RM. And the position is controlled. Light from the pattern formed on the reticle R forms a reticle pattern image on the wafer W, which is a photosensitive substrate, via the projection optical system PL.

  The wafer W is held parallel to the XY plane on the wafer stage WS via the wafer holder table WT. Then, a pattern image is formed in the rectangular still exposure region (effective exposure region) on the wafer W so as to optically correspond to the rectangular illumination region on the reticle R. The wafer stage WS can be moved two-dimensionally along the wafer surface (that is, the XY plane) by the action of a drive system (not shown), and its position coordinates are measured by an interferometer WIF using a wafer moving mirror WM. In addition, the position is controlled.

  Further, in the exposure apparatus of the present embodiment, between the optical member arranged closest to the reticle among the optical members constituting the projection optical system PL and the boundary lens Lb arranged closest to the wafer (see FIG. 3). Thus, the inside of the projection optical system PL is configured to be kept in an airtight state, and the gas inside the projection optical system PL is replaced with an inert gas such as helium gas or nitrogen, or is almost kept in a vacuum state. . Further, a reticle R and a reticle stage RS are arranged in a narrow optical path between the illumination optical system IL and the projection optical system PL, but a casing (not shown) that hermetically surrounds the reticle R and the reticle stage RS. Is filled with an inert gas such as nitrogen or helium gas, or is kept in a vacuum state.

  Referring to FIG. 3, in the present embodiment, the optical path between the boundary lens Lb disposed on the most wafer side of the projection optical system PL and the wafer W is filled with a liquid Lm having a refractive index greater than 1.1. Has been. For example, pure water can be used as the liquid Lm as the immersion liquid. The boundary lens Lb is formed by joining a first optical member Lb1 formed of synthetic quartz and in contact with the liquid Lm and a second optical member Lb2 formed of fluorite by optical contact. Here, the first optical member Lb1 is a plane-parallel plate, and the second optical member Lb2 is a plano-convex lens having a convex surface facing the reticle side.

  In order to continue filling the liquid Lm in the optical path between the boundary lens Lb of the projection optical system PL and the wafer W, for example, the technique disclosed in International Publication No. WO99 / 49504 or Japanese Patent Laid-Open No. 10-303114 The technique disclosed in the publication can be used. In the technique disclosed in International Publication No. WO99 / 49504, the liquid Lm adjusted to a predetermined temperature from the liquid supply device via the supply pipe and the discharge nozzle fills the optical path between the boundary lens Lb and the wafer W. Then, the liquid is recovered from the wafer W via the recovery pipe and the inflow nozzle by the liquid supply device.

  On the other hand, in the technique disclosed in Japanese Patent Laid-Open No. 10-303114, the wafer holder table WT is configured in a container shape so that the liquid Lm can be accommodated, and the wafer W is placed at the center of the inner bottom (in the liquid). Is positioned and held by vacuum suction. Further, the lens barrel tip of the projection optical system PL reaches the liquid, and the optical surface on the wafer side of the boundary lens Lb reaches the liquid.

  As described above, an atmosphere in which exposure light is hardly absorbed is formed over the entire optical path from the light source 100 to the wafer W. Therefore, using a drive system and an interferometer (RIF, WIF) or the like, collective exposure is performed while two-dimensionally driving and controlling the wafer W in a plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL. Thus, the pattern of the reticle R is sequentially exposed on the shot area of the wafer W in accordance with the so-called step-and-repeat method.

  As described above, in the present embodiment, the liquid Lm such as pure water is interposed in the optical path between the projection optical system PL and the wafer W that is the photosensitive substrate. In the projection optical system PL, the boundary lens Lb is a joined optical member formed by joining a first optical member Lb1 formed of synthetic quartz and in contact with the liquid Lm and a second optical member Lb2 formed of fluorite. It is composed. Furthermore, the thickness TA of the first optical member Lb1 is set so as to satisfy the above-described conditional expression (1).

  Therefore, in the projection optical system PL of this embodiment, compaction does not substantially occur in the second optical member Lb2 formed of fluorite. In addition, since the thickness TA of the first optical member Lb1 formed of synthetic quartz is set to be sufficiently small, the influence of compaction on the first optical member Lb1 can be kept small. As a result, it is possible to suppress a reduction in the imaging performance of the projection optical system PL due to the influence of compaction in the boundary lens Lb.

  Further, in the present embodiment, a first quartz formed of synthetic quartz that does not dissolve in pure water between the second optical member Lb2 formed of fluorite that is easily dissolved in pure water and the liquid Lm made of pure water. The optical member Lb1 is interposed in a close contact state. Accordingly, the optical surface of the second optical member Lb2 is not damaged by the influence of pure water, and the optical surface of the boundary lens Lb is not damaged by the influence of pure water. The performance can be maintained well over a long period of time.

  As described above, in the projection optical system PL of the present embodiment, the influence of compaction is achieved while ensuring a large effective image-side numerical aperture by interposing the liquid Lm in the optical path between the wafer W, which is the image plane. Good imaging performance can be maintained over a long period of time without being substantially damaged by the immersion liquid Lm. Therefore, in the exposure apparatus of the present embodiment, a high resolution is achieved by using the projection optical system PL that can maintain good imaging performance over a long period while ensuring a large effective image-side numerical aperture. Projection exposure can be performed stably over a long period of time.

  In the projection optical system PL of the present embodiment, the second optical member Lb2 is configured as a plano-convex lens having a convex surface facing the reticle, and the optical surface on the reticle side of the second optical member Lb2 faces the convex surface toward the reticle. Therefore, the image-side numerical aperture can be increased. In addition, since the first optical member Lb1 is configured as a plane-parallel plate and the second optical member Lb2 is configured as a plano-convex lens with the plane facing the wafer side, the first optical member Lb1 and the second optical member Lb2 The joining surface becomes planar, and good optical contact can be realized.

  By the way, when the liquid Lm enters the joint surface between the first optical member Lb1 and the second optical member Lb2 by capillary action, the first optical member Lb1 and the second optical member Lb2 joined by the optical contact are separated (separated). There is a possibility that. Therefore, in this embodiment, as shown in FIG. 4, for example, an overcoating 41 is used as a liquid intrusion preventing unit for preventing the liquid Lm from entering the joint surface between the first optical member Lb1 and the second optical member Lb2. Is preferably formed on the side surfaces of the first optical member Lb1 and the second optical member Lb2.

  Further, each optical member (such as a lens) constituting the projection optical system PL needs to be held with sufficient strength, and thus each held optical member needs to have a sufficiently large thickness. In addition, a small amount of light energy is absorbed in each optical member during exposure and converted to heat. If an optical member made of an optical material having high thermal conductivity is in contact with the lens barrel, heat conduction to the lens barrel is achieved. As a result, the temperature rise of the optical member is mitigated, and as a result, the heat conduction to the liquid can be kept small.

  From the above two viewpoints, in the present embodiment, as shown in FIG. 5, the boundary is provided through the second optical member Lb2 formed of fluorite having a sufficiently large thickness and a relatively high thermal conductivity. It is desirable that the lens (bonding optical member) Lb is held by the lens barrel 51. In addition, with this configuration, it is possible to easily replace the first optical member Lb1 that is disposed on the wafer W side and is susceptible to contamination from the resist while the boundary lens Lb is held by the lens barrel 51.

  As described above, since the fluoride dissolves in water, it is necessary to prevent water from entering the second optical member Lb2 formed of fluorite. In the present embodiment, the side surface of the first optical member Lb1 and the inner side surface of the lens barrel 51 are disposed sufficiently close to each other, and the water repellency is provided on the side surface of the first optical member Lb1 and the inner side surface of the lens barrel 51 facing each other. By performing the treatment (for example, forming the water-repellent coating 52), it is possible to prevent pure water from entering the second optical member Lb2. Alternatively, as shown in FIG. 5, for example, an O-ring 53 is used as a waterproof element for preventing intrusion of pure water (liquid) between the side surface of the first optical member Lb1 and the inner side surface of the lens barrel 51 facing the first optical member Lb1. By providing, pure water can be prevented from entering the second optical member Lb2.

  Further, in addition to the water repellent treatment on the side surface of the first optical member Lb1 and the inner side surface of the lens barrel 51, the side surface of the second optical member Lb2 may be subjected to water repellency treatment (for example, water repellent coating). In addition to the method of providing a waterproof element (for example, an O-ring 53) between the side surface of the first optical member Lb1 and the inner side surface of the lens barrel 51 facing the first optical member Lb1, the first optical member Lb1 as shown in FIG. A method of applying overcoating as a liquid intrusion preventing unit to the side surface of the second optical member Lb2 may be applied. In addition to the technique of performing water repellency treatment on the side surface of the first optical member Lb1 and the inner side surface of the lens barrel 51, liquid is applied to the side surfaces of the first optical member Lb1 and the second optical member Lb2 as shown in FIG. You may apply the method of giving the overcoating as an intrusion prevention means.

  In the above-described embodiment, the first optical member Lb1 and the second optical member Lb2 are joined by optical contact. However, the present invention is not limited to this, and the first optical member is used by using another appropriate method. Lb1 and the second optical member Lb2 can also be joined. In the above-described embodiment, pure water is used as the immersion liquid. However, the present invention is not limited to this, and other appropriate liquids can be used according to the wavelength of light.

  In the above-described embodiment, the first optical member Lb1 is formed of synthetic quartz, and the second optical member Lb2 is formed of fluorite. However, the present invention is not limited to this, and the first optical member Lb1 can also be formed using, for example, an appropriate optical material having a property that does not substantially dissolve in immersion liquid. Further, for example, an appropriate optical material having a property that compaction is not substantially generated, for example, an appropriate fluoride material other than fluorite (for example, calcium fluoride, barium fluoride, lithium fluoride, sodium fluoride, strontium fluoride, etc. ) May be used to form the second optical member Lb2.

  In the above-described embodiment, the first optical member Lb1 is configured as a plane parallel plate, and the second optical member Lb2 is configured as a plano-convex lens having a convex surface facing the reticle. However, the present invention is not limited to this, and various modifications of the shapes of the first optical member Lb1 and the second optical member Lb2 are possible. In the above-described embodiment, the first optical member Lb1 is provided. However, the number of the first optical members Lb1 is not limited to one.

  In the exposure apparatus of the above-described embodiment, the reticle (mask) is illuminated by the illumination device (illumination process), and the transfer pattern formed on the mask is exposed to the photosensitive substrate using the projection optical system (exposure process). Thus, a micro device (semiconductor element, imaging element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Hereinafter, referring to the flowchart of FIG. 6 for an example of a method for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the present embodiment. I will explain.

  First, in step 301 of FIG. 6, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the one lot of wafers. Thereafter, in step 303, using the exposure apparatus of the present embodiment, the image of the pattern on the mask is sequentially exposed and transferred to each shot area on the wafer of one lot via the projection optical system. Thereafter, in step 304, the photoresist on the one lot of wafers is developed, and in step 305, the resist pattern is etched on the one lot of wafers to form a pattern on the mask. Corresponding circuit patterns are formed in each shot area on each wafer.

  Thereafter, a device pattern such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer. According to the semiconductor device manufacturing method described above, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput. In steps 301 to 305, a metal is deposited on the wafer, a resist is applied on the metal film, and exposure, development, and etching processes are performed. Prior to these processes, on the wafer. It is needless to say that after forming a silicon oxide film, a resist may be applied on the silicon oxide film, and steps such as exposure, development, and etching may be performed.

  In the exposure apparatus of this embodiment, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 7, in a pattern forming process 401, a so-called photolithography process is performed in which a mask pattern is transferred and exposed to a photosensitive substrate (such as a glass substrate coated with a resist) using the exposure apparatus of the present embodiment. By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate undergoes steps such as a developing step, an etching step, and a resist stripping step, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming step 402.

  Next, in the color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three of R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning line direction. Then, after the color filter forming step 402, a cell assembly step 403 is executed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like.

  In the cell assembly step 403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern formation step 401 and the color filter obtained in the color filter formation step 402, and a liquid crystal panel (liquid crystal cell) is obtained. ). Thereafter, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display element, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

In the above-described embodiment, the ArF excimer laser light source is used. However, the present invention is not limited to this, and other appropriate light sources such as a KrF excimer laser light source and an F ₂ laser light source can also be used. In the above-described embodiment, the present invention is applied to the projection optical system mounted on the exposure apparatus. However, the present invention is not limited to this, and other general projection optical systems and other general optical systems are used. The present invention can also be applied to various imaging optical systems. In the above-described embodiment, the magnification of the projection optical system is the reduction magnification. However, when applied to other general imaging optical systems, the magnification may be an enlargement magnification or the same magnification.

  As described above, when the immersion method is used, the numerical aperture NA of the projection optical system may be 0.9 to 1.5. When the numerical aperture NA of the projection optical system becomes large in this way, the imaging performance may deteriorate due to the polarization effect with random polarized light conventionally used as exposure light. desirable. In that case, linearly polarized illumination is performed in accordance with the longitudinal direction of the line pattern of the mask (reticle) line-and-space pattern, and the S-polarized component (along the longitudinal direction of the line pattern) is generated from the mask (reticle) pattern. It is preferable that a large amount of diffracted light (polarization direction component) is emitted.

  In the above-described embodiment, a light-transmitting mask in which a predetermined light-shielding pattern (or phase pattern / dimming pattern) is formed on a light-transmitting substrate, or a predetermined reflecting pattern is formed on a light-reflecting substrate. Although the light reflection type mask is used, instead of these masks, an electronic mask that forms a transmission pattern, a reflection pattern, or a light emission pattern based on electronic data of a pattern to be exposed may be used. Such an electronic mask is disclosed in, for example, US Pat. No. 6,778,257. This US Pat. No. 6,778,257 is hereby incorporated by reference. Note that the above-described electronic mask is a concept including both a non-light-emitting image display element and a self-light-emitting image display element.

Explanation of symbols

Lb Boundary lens Lb1 First optical member Lb2 Second optical member Lm Liquid (pure water: immersion liquid)
41 Overcoating 51 Lens barrel 52 Water repellent coating 53 O-ring 100 Laser light source IL Illumination optical system R Reticle RS Reticle stage PL Projection optical system W Wafer WS Wafer stage

Claims (24)

An imaging optical system that optically conjugates a first surface and a second surface, wherein when the refractive index of the atmosphere in the optical path of the imaging optical system is 1, the imaging optical system and the first surface in the optical path imaging optical system Ru filled with a liquid having a refractive index larger than 1.1 between the two surfaces,
On the second surface side in the imaging optical system, a joint formed by joining a first optical member formed of a first optical material and in contact with the liquid, and a second optical member formed of the second optical material. An optical member is arranged,
When the thickness of the first optical member is TA and the maximum image height on the second surface is IH,
0.1 <TA / IH <1.1
An imaging optical system characterized by satisfying the following conditions. The imaging optical system according to claim 1, wherein the first optical member and the second optical member are joined by an optical contact. The imaging optical system according to claim 1, wherein the optical surface on the first surface side of the second optical member has a convex surface facing the first surface side. The imaging optical system according to any one of claims 1 to 3, wherein a joint surface between the first optical member and the second optical member is planar. The wavelength of the light used is 300 nm or less,
The imaging optical system according to claim 1, wherein the second optical material is a fluoride. The first optical material is synthetic quartz;
The second optical material is fluorite;
The imaging optical system according to claim 1, wherein the liquid is pure water. Liquid intrusion prevention means provided on side surfaces of the first optical member and the second optical member for preventing the liquid from entering the joint surface between the first optical member and the second optical member. The imaging optical system according to claim 1, wherein the imaging optical system is an optical system. The imaging optical system according to claim 1, wherein the bonding optical member is held by a lens barrel via the second optical member. The side surface of the first optical member and the inner side surface of the lens barrel are arranged close to each other, and the side surface and the inner side surface facing each other are subjected to water repellency treatment. The imaging optical system described. 9. The connection according to claim 8, wherein a waterproof element is provided between a side surface of the first optical member and an inner side surface of the lens barrel facing the first optical member to prevent the liquid from entering. Image optics. An imaging optical system that optically conjugates a first surface and a second surface, wherein when the refractive index of the atmosphere in the optical path of the imaging optical system is 1, the imaging optical system and the first surface in the optical path imaging optical system Ru filled with a liquid having a refractive index larger than 1.1 between the two surfaces,
On the most second surface side in the imaging optical system, the first optical member formed by the first optical material and in contact with the liquid is joined to the second optical member formed by the second optical material. A bonding optical member is disposed ;
The bonding optical member is held by a lens barrel via the second optical member,
An imaging optical system , wherein a side surface of the first optical member and an inner side surface of the lens barrel are arranged close to each other, and the side surface and the inner side surface facing each other are subjected to water repellency treatment. . An imaging optical system that optically conjugates a first surface and a second surface, wherein when the refractive index of the atmosphere in the optical path of the imaging optical system is 1, the imaging optical system and the first surface In an imaging optical system where the optical path between the two surfaces is filled with a liquid having a refractive index greater than 1.1,
On the most second surface side in the imaging optical system, the first optical member formed of the first optical material and in contact with the liquid is joined to the second optical member formed of the second optical material. A bonding optical member is disposed;
The bonding optical member is held on the lens barrel via the second optical member,
An imaging optical system , wherein a waterproof element for preventing the liquid from entering is provided between a side surface of the first optical member and an inner side surface of the lens barrel facing the first optical member . The imaging optical system according to claim 11, wherein the second optical member does not contact the liquid . Liquid intrusion prevention means provided on side surfaces of the first optical member and the second optical member for preventing the liquid from entering the joint surface between the first optical member and the second optical member. The imaging optical system according to claim 13 . The imaging optical system according to claim 1, wherein the second optical material is a material of a different type from the first optical material . The imaging optical system according to any one of claims 11 to 15, wherein the first optical member and the second optical member are joined by optical contact . The imaging optical system according to any one of claims 11 to 16 , wherein the first optical surface of the second optical member has a convex surface facing the first surface . The imaging optical system according to claim 11 , wherein a joint surface between the first optical member and the second optical member is planar . When the thickness of the first optical member is TA and the maximum image height on the second surface is IH,
0.1 <TA / IH <1.1
The imaging optical system according to claim 11 , wherein the following condition is satisfied . Wherein the optical system, the imaging optical system according to any one of claims 1 to 19, characterized in that a projection optical system for forming an image of the first surface on a second surface. 21. The image forming optical system according to claim 1, wherein an image of a pattern set on the first surface is formed on a photosensitive substrate set on the second surface. An exposure apparatus characterized by that . The exposure apparatus according to claim 21, further comprising an illumination system for illuminating the mask set on the first surface . An illumination process for illuminating a mask set on the first surface, and an image of a pattern formed on the mask via the imaging optical system according to any one of claims 1 to 20, wherein the second surface And an exposure step of projecting and exposing on a photosensitive substrate set to 1) . A step of supplying a predetermined pattern, and an image of the pattern is projected and exposed onto a photosensitive substrate set on the second surface via the imaging optical system according to any one of claims 1 to 20. A device manufacturing method comprising an exposure step .

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