JP2006173340A - Exposure apparatus and exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an immersion exposure apparatus which performs exposure with a liquid filling up a space between a substrate and an optical system which excels in safety and can performs exposure with accuracy. <P>SOLUTION: The exposure apparatus 1 comprises a holding means 2 for holding the substrate 5, the optical system 3 which irradiates exposure light for projecting a prescribed pattern onto the substrate 5 held by the holding means 2, and a liquid supplying means 4 which fills up a space 6 between the substrate 5 held by the holding means 2 and the optical system 3 with a liquid 7. The liquid 7 filling up the space 6 between the substrate 5 held by the holding means 2 and the optical system 3 is grounded. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus and an exposure method. More specifically, the present invention relates to an exposure apparatus and an exposure method of an immersion type exposure method that performs exposure by filling a liquid between a substrate and an optical system, which is excellent in safety and can perform exposure with high accuracy.

  When manufacturing a semiconductor element or the like, a reticle (mask) pattern as a photomask is transferred to a substrate coated with a photoresist via an optical system, for example, a stepper type that transfers each shot region on the substrate, or A step-and-scan type exposure apparatus is used.

  The theoretical limit value of the resolution of the projection optical system constituting the optical system used in such an exposure apparatus becomes higher as the exposure wavelength used is shorter and the numerical aperture of the projection optical system is larger. For this reason, with the miniaturization of the integrated circuit pattern size, the exposure wavelength, which is the wavelength of radiation used in the exposure apparatus, has become shorter year by year, and the numerical aperture of the projection optical system has also increased.

Also, when performing exposure, the depth of focus is important as well as the resolution. The theoretical limit values of the resolution R and the depth of focus δ are expressed by the following equations (i) and (ii), respectively.
R = k1 · λ / NA (i)
δ = k ² · λ / NA ² (ii)

Here, λ is the exposure wavelength, k1 and k2 are process coefficients, NA is the numerical aperture of the projection optical system, and the refractive index of air is 1, and is defined by the following formula (ii ′). That is, when the same resolution R is obtained, a greater depth of focus δ can be obtained by using radiation having a short wavelength.
NA = sin θ (ii ′)
(However, θ is the maximum incident angle of exposure light on the resist surface.)

  As described above, so far, the demand for miniaturization of integrated circuits has been met by shortening the wavelength of the exposure light source and increasing the numerical aperture, and now 90 nm (using an ArF excimer laser (wavelength 193 nm) as the exposure light source). Mass production of half pitch) is being studied for the most advanced integrated circuits.

However, it is said that the next generation 65 nm (half pitch) or 45 nm (half pitch), which has been further miniaturized, is difficult to achieve only by using an ArF excimer laser. For these next-generation technologies, the use of short-wavelength light sources such as F ₂ excimer laser (wavelength 157 nm) and EUV (wavelength 13 nm) has been studied. However, the technical difficulty of using these light sources is high. Currently, it is difficult to use.

  By the way, in the exposure technique described above, a photoresist film is formed on the surface of the substrate to be exposed, and a pattern is transferred to the photoresist film. In the conventional exposure apparatus, the space in which the substrate is arranged is filled with air having a refractive index of 1. At this time, when the space between the substrate and the lens of the optical system of the exposure apparatus is filled with a medium having a refractive index n, it has been reported that the depth of focus is expanded more than double the refractive index. In addition, it is known that an optical system having a large NA that cannot be realized in the case of air can be realized by using a liquid, so that the resolving power is improved.

  A projection exposure method that can increase the NA of the optical system for exposure to 1 or more, transfer a finer pattern, or increase the depth of focus is called an immersion exposure method. An exposure apparatus using an immersion type exposure system is disclosed (for example, see Patent Documents 1 to 3).

As an exposure apparatus of such an immersion type exposure system, for example, as disclosed in Patent Document 2, a mask is illuminated with an exposure beam, and the substrate is exposed with the exposure beam via a projection optical system. In the projection exposure apparatus, a projection exposure apparatus comprising a liquid supply device that flows a liquid so as to fill a space between the projection optical system and the substrate, and changes a direction in which the liquid flows according to a moving direction of the substrate. Can be mentioned.
JP-A-10-303114 International Publication No. 99/49504 Pamphlet JP 2004-207711 A

  However, in such an immersion-type exposure apparatus, it is possible to shorten the effective wavelength and transfer a finer pattern, but the substrate is always in contact with the liquid during exposure. Static electricity is charged on the liquid or the substrate. For this reason, charged static electricity affects the distribution of ionic substances in the liquid and adversely affects exposure.For example, when a flammable substance is used as the liquid, sparks are generated by the charged static electricity. There was a problem that the liquid could ignite.

  The present invention has been made in view of the above-described problems of the prior art, and is excellent in safety and capable of performing exposure with high accuracy. The exposure is performed by filling a liquid between a substrate and an optical system. An immersion type exposure apparatus and an exposure method are provided.

  According to the present invention, the following exposure apparatus and exposure method are provided.

  [1] A holding means for holding a substrate, an optical system for irradiating exposure light for projecting a predetermined pattern onto the substrate held by the holding means, the substrate held by the holding means, and the An exposure apparatus comprising a liquid supply means for filling a space between the optical system and the liquid that fills the space between the substrate and the optical system held by the holding means. An exposure apparatus that is electrically grounded (hereinafter sometimes referred to as “first invention”).

  [2] The liquid supply unit supplies the liquid to the space between the substrate held by the holding unit and the optical system, and the liquid collects the liquid supplied to the space. The exposure according to [1], further including a recovery unit, wherein a ground is disposed in at least one of the liquid supply unit and the liquid recovery unit, and electrical grounding is performed on the liquid. apparatus.

  [3] The [1] or [1], wherein a ground is disposed in the space between the substrate held by the holding means and the optical system, and the liquid is electrically grounded. 2]. The exposure apparatus according to 2].

  [4] The exposure apparatus according to any one of [1] to [3], wherein the liquid is an organic solvent.

  [5] The exposure apparatus according to any one of [1] to [4], wherein the substrate held by the holding unit is further electrically grounded.

  [6] The exposure apparatus according to any one of [1] to [5], wherein the holding unit and / or the optical system is further electrically grounded.

  [7] The exposure apparatus according to any one of [1] to [6], wherein in the exposure apparatus, at least a movable part in a region where the volatile component of the liquid exists is electrically grounded.

  [8] A liquid is filled in a space between the substrate held by the holding unit and an optical system that emits exposure light for projecting a predetermined pattern onto the substrate held by the holding unit, An exposure method for exposing the substrate through a liquid, wherein the liquid that fills the space between the substrate held by the holding unit and the optical system is electrically grounded ( Hereinafter, it may be referred to as “second invention”).

  [9] A ground is provided in the liquid supply means for filling the liquid in the space between the substrate and the optical system held by the holding means, and the liquid is electrically grounded. The exposure method according to [8] above.

  [10] In the above [8] or [9], in which a ground is disposed in the space between the substrate held by the holding means and the optical system to electrically ground the liquid The exposure method as described.

  [11] The exposure method according to any one of [8] to [10], wherein an organic solvent is used as the liquid.

  [12] The exposure method according to any one of [8] to [11], wherein the substrate held by the holding unit is further electrically grounded.

  [13] The exposure method according to any one of [8] to [12], wherein the holding unit and / or the optical system is further electrically grounded.

  [14] The exposure according to any one of [8] to [13], wherein electrical grounding is performed at least in a region where the volatile component of the liquid exists in the vicinity of the space between the substrate and the optical system. Method.

  According to the exposure apparatus and the exposure method of the present invention, since the liquid that fills the space between the optical system and the substrate held by the holding unit by the liquid supply unit is electrically grounded, safety is ensured. In addition, exposure can be performed with high accuracy.

  Hereinafter, embodiments of the present invention (first and second inventions) will be described in detail. However, the present invention is not limited to these embodiments, and a person skilled in the art can depart from the scope of the present invention. It should be understood that changes, improvements, and the like can be made as appropriate based on general knowledge of the above.

  FIG. 1 is an explanatory view schematically showing a configuration of an embodiment of an exposure apparatus of the present invention (first invention). As shown in FIG. 1, the exposure apparatus 1 of the present embodiment irradiates exposure light for projecting a predetermined pattern onto the holding means 2 for holding the substrate 5 and the substrate 5 held by the holding means 2. The exposure apparatus 1 includes an optical system 3 that performs the above operation, and a liquid supply unit 4 that fills the space 6 between the substrate 5 and the optical system 3 held by the holding unit 2. The exposure apparatus 1 is configured to be electrically grounded with respect to the liquid 7 that fills the space 6 between the substrate 5 and the optical system 3 held by the optical system 3. In the exposure apparatus 1 of the present embodiment, an earth 8 (for example, an earth wire) is connected to the liquid 7 for electrical grounding. Here, the substrate 5 includes a substrate in which a photoresist film, an upper layer film (top coat film) and the like are provided on the surface on the side irradiated with the exposure light.

  An exposure apparatus 1 according to the present embodiment holds a substrate 5 having a photoresist film or an upper layer film disposed on a surface thereof by a holding unit 2 and irradiates exposure light for projecting a predetermined pattern from an optical system 3. Then, the substrate 5 is developed to form a predetermined resist pattern on the substrate 5, and a liquid 7 is placed in a space 6 between the substrate 5 held by the holding means 2 and the optical system 3. This is an exposure apparatus 1 of a so-called immersion type exposure system provided with a liquid supply means 4 for satisfying the above conditions. This immersion type exposure apparatus 1 has a depth of focus on the surface of the substrate 5 as compared with the case where the space 6 between the substrate 5 held by the holding means 2 and the optical system 3 is filled with air and exposed. Can be multiplied by n (where n is the refractive index of the liquid 7).

  As shown in FIG. 1, in the exposure apparatus 1 of the present embodiment, for example, static electricity generated by the flow of the liquid 7 is discharged to the outside by the ground 8, so that the static electricity is charged in the liquid 7. Can be effectively prevented. For this reason, the influence of static electricity at the time of exposure can be removed, and highly accurate exposure can be realized. In addition, since the occurrence of sparks and the like due to contact of movable parts is prevented, for example, even if a volatile substance having a low flash point such as an organic solvent is used as the liquid 7, exposure can be performed safely. . For example, in a conventional exposure apparatus, when an insulated material touches when a wafer is delivered, an electrostatic spark may occur. The exposure apparatus 1 of the present embodiment realizes significant static electricity prevention in the apparatus, and can suppress the occurrence of sparks even in a movable part disposed in the vicinity of the liquid 7, so that exposure can be performed safely. It can be carried out. In the exposure apparatus 1 of the present embodiment, safety can be further improved by further electrically grounding such a movable part itself.

  In the exposure apparatus 1 of the present embodiment, the method for filling the liquid 7 in the space 6 between the substrate 5 held by the holding means 2 and the optical system 3 is not particularly limited, and examples thereof include a moving pool method and a semimming method. The stage method and the local fill method (local immersion method) can be used (see the seminar text on the special seminar immersion exposure technology (held on May 27, 2004)), but the local immersion method as shown in FIG. The used exposure apparatus 1 can be used particularly preferably because the amount of the liquid 7 to be used is small.

  Further, in the exposure apparatus 1 of the present embodiment, electrical grounding is indirectly performed on the liquid 7 filling the space 6 between the substrate 5 and the optical system 3 held by the holding unit 2. For example, in the exposure apparatus 1, electrical grounding may be performed with respect to a portion that is in contact with a part of the liquid 7 and has conductivity. In the exposure apparatus 1 of the present embodiment, the space 6 between the substrate 5 held by the holding unit 2 and the optical system 3 is more specifically the substrate 5 held by the holding unit 2 and the optical system 3. A space 6 between the projection optical system 13 and the tip of the system 3.

  As described above, the exposure apparatus 1 of the present embodiment suppresses the generation of static electricity due to the flow of the liquid 7, and effectively prevents the occurrence of sparks and the like due to static electricity due to the presence of movable parts and the like inside the exposure apparatus 1. Therefore, it can be suitably used when the liquid 7 filling the space 6 between the substrate 5 and the optical system 3 held by the holding means 2 is a low flash point or volatile organic solvent. Currently, pure water is mainly studied as the liquid 7 that fills the space 6. However, as the pattern to be exposed is further refined, the liquid 7 has a high transmittance at the exposure wavelength of the exposure light and is pure. It is necessary to use a liquid having a sufficiently high refractive index as compared with water. An organic solvent can be given as one of the liquids satisfying such requirements. However, since organic solvents have a low flash point and some substances have volatility, for example, an atmosphere in which the liquid 7 is present or volatilized. When a spark due to static electricity occurs in the area where the liquid crystal exists, the liquid 7 ignites and burns in the exposure apparatus 1. In the exposure apparatus 1 of the present embodiment, since the liquid 7 filling the space 6 between the substrate 5 and the optical system 3 held by the holding unit 2 is electrically grounded, for example, As described above, even when an organic solvent is used as the liquid 7, exposure can be performed safely and accurately.

  In the exposure apparatus 1 of the present embodiment, the method of electrically grounding the liquid 7 filling the space 6 between the substrate 5 held by the holding means 2 and the optical system 3 is not particularly limited. As shown in FIG. 1, the liquid supply unit 4 supplies the liquid 7 to the space 6 between the substrate 5 held by the holding unit 2 and the optical system 3, and the liquid supplied to the space 6. In the case of having the liquid recovery unit 15 that recovers the liquid 7, a ground 8 is disposed at least at a part of the liquid supply unit 14 and the liquid recovery unit 15 so that the liquid 7 is electrically grounded. It is preferable that More specifically, when the liquid supply unit 14 or the liquid recovery unit 15 constituting the liquid supply unit 4 has a supply tank 21 or a recovery tank 22 for storing the liquid 7, this supply is performed. The tank 21 and the recovery tank 22 may be provided with a ground so as to be electrically grounded with respect to the liquid 7, or the liquid supply unit 14 constituting the liquid supply means 4 and the liquid recovery When the portion 15 has a supply channel 23 and a recovery channel 24 for moving the liquid 7, an earth is provided inside the supply channel 23 and the recovery channel 24, Electrical grounding may be performed. Further, for example, when the tip of the supply flow path 23 that supplies the liquid 7 to the space 6 is thin and has a nozzle shape, or the tip of the recovery flow path 24 that collects the liquid 7 that has passed through the space 6 is wide. In the case of a nozzle shape, a ground may be provided at the tip of the supply channel 23 and the recovery channel 24 that are in the nozzle shape. Further, the grounding may be performed in a region surrounding the open region of the tip portion of the projection optical system 13 constituting the optical system 3.

  Further, as described above, the ground 8 is not disposed in the liquid supply unit 14 or the liquid recovery unit 15 of the liquid supply unit 4, but, for example, the substrate 5 held by the holding unit 2 and the optical system 3 An earth 8 may be provided in the space 6 between them, and the liquid 7 may be electrically grounded. In the exposure apparatus 1 of the present embodiment, the liquid 7 is allowed to pass through the space 6 between the substrate 5 held by the holding means 2 and the optical system 3 by the liquid supply means 4. It is also possible to perform electrical grounding. In the immersion exposure type exposure apparatus 1 that allows the liquid 7 to pass through the space 6 between the substrate 5 held by the holding means 2 and the optical system 3, exposure can be performed with higher accuracy. In order to allow the liquid 7 to pass through the space 6 so as to be uniform, a ground is disposed in a part of the space 6 so that the entire liquid 7 is electrically grounded. When the ground 8 is arranged in the space 6 in this way, the liquid 7 is passed through a region wider than the region where the exposure is actually performed, and the ground is provided at a site that does not affect the actual exposure. 8 is preferably arranged.

  Although not shown in the drawing, the exposure apparatus of the present embodiment performs exposure by immersing the substrate in a liquid supply means filled with liquid, and using the above-described moving pool method or simmering stage method. In the case of the exposure apparatus of the type exposure system, it is possible to perform electrical grounding for the entire liquid by performing electrical grounding at a part of the liquid supply means filled with the liquid. .

  As for the method of electrically grounding the liquid 7 in the exposure apparatus 1 of the present embodiment, the method of connecting the ground 8 to a part of the liquid supply means 4 as described above, or the holding means 2 holds the liquid. The method is not limited to the method of connecting the ground 8 to the liquid 7 passing through the space 6 between the substrate 5 and the optical system 3.

  Further, when an organic liquid (organic solvent) is used as the liquid 7 used in the exposure apparatus 1 of the present embodiment, the liquid 7 may be highly volatile. In such a case, the volatilized liquid component may diffuse into the exposure apparatus 1. Therefore, it is preferable to prevent the generation of static electricity not only in the region where the liquid 7 flows but also in the region where the component in which the liquid 7 has volatilized can diffuse. That is, for example, as in the exposure apparatus 1 shown in FIG. 2, it is necessary to sufficiently ground the movable portion 25 such as a wafer transfer portion or a robot arm using such a volatile liquid. Is important. Here, FIG. 2 is an explanatory view schematically showing the arrangement of another embodiment of the exposure apparatus of the present invention (first invention). The same elements as those constituting the exposure apparatus shown in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

  Although it has been described that the exposure apparatus 1 of the present embodiment as shown in FIG. 1 can be suitably used when the liquid 7 is an organic solvent, as the particularly preferable liquid 7, for example, the exposure apparatus 1 operates. It is preferable that it is a liquid in the temperature range to be used, and is an alicyclic hydrocarbon compound or a cyclic hydrocarbon compound containing a silicon atom in the ring structure. Further, such an alicyclic hydrocarbon compound or a cyclic hydrocarbon compound containing a silicon atom in the ring structure has a light transmittance of 90% or more at an optical path length of 1 mm at a wavelength of 193 nm and a refractive index of a liquid at a wavelength of 193 nm. Is preferably 1.6 or more. Such a liquid has a refractive index larger than that of pure water and has excellent transparency similar to that of pure water, and can realize exposure with higher resolution and depth of focus.

  Examples of such alicyclic hydrocarbon compounds or cyclic hydrocarbon compounds containing a silicon atom in the ring structure include decalin and the like as candidates. Decalin has a refractive index of 1.64 at a wavelength of 193 nm (at a temperature of 23 ° C.), and a liquid having a transmittance of 97% or more at a liquid thickness of 1 mm.

  So far, in the exposure apparatus 1 of the present embodiment, electrical grounding is performed on the liquid 7 filling the space 6 between the substrate 5 and the optical system 3 held by the holding means 2. However, in the exposure apparatus 1 of the present embodiment, the substrate 5 held by the holding unit 2 may be further electrically grounded. For example, when the substrate 5 is actually exposed using the exposure apparatus 1 shown in FIG. 1, the liquid 7 is always passed over the substrate 5 held by the holding unit 2. For this reason, by further electrically grounding the substrate 5 held by the holding means 2, the effect of removing static electricity charged in the liquid 7 can be improved and the substrate 5 itself is charged. Static electricity can also be removed, and exposure can be performed safely and with high accuracy. For example, when the substrate 5 is a silicon wafer, the stage 18 holding the substrate 5 is electrically grounded.

  Furthermore, in the exposure apparatus 1 of the present embodiment, the holding means 2 and / or the optical system 3 disposed relatively close to the liquid 7 is further electrically grounded. Also good. For example, the holding unit 2 and the optical system 3 may be charged when static electricity is generated by driving such as positioning or static electricity generated by the liquid 7 flows. As described above, since the holding unit 2 and the optical system 3 are disposed relatively close to the liquid 7, static electricity charged in the holding unit 2 and the optical system 3 may adversely affect the exposure, When a spark is generated around the optical system 3, there is a possibility of jumping to the liquid 7. For this reason, from the viewpoint of improving safety and increasing the accuracy of exposure, it is preferable that the holding means 2 and / or the optical system 3 be further electrically grounded. In the exposure apparatus 1 of the present embodiment, when the exposure apparatus 1 further includes components other than the holding unit 2 and the optical system 3, the components are also electrically as possible as possible. It is preferable that proper grounding is performed.

  As the optical system 3 constituting the exposure apparatus 1 of the present embodiment, an optical system used in a conventionally known exposure apparatus can be suitably used. For example, an illumination optical system 11 serving as a light source as shown in FIG. An optical system 3 having a mask 12 on which a predetermined pattern is formed and a projection optical system 13 that projects the pattern of the mask 12 onto the substrate 5 can be given as a preferred example.

  The illumination optical system 11 is an optical system for irradiating the mask 12 with exposure light. Examples of the illumination optical system 11 suitably used in the exposure apparatus 1 of the present embodiment include an exposure light source and an exposure light source. An illumination optical system having a condenser lens that condenses light by controlling the directivity of the light and a field stop that adjusts the shape of the exposure light applied to the mask 12 can be given as preferred examples. In addition, such an illumination optical system 11 may further include a relay lens, a fly-eye lens, a filter, a diffusion plate, and the like, although not shown.

  There is no particular limitation on the type of exposure light emitted from the exposure light source used in the illumination optical system 11, and depending on the photoresist film applied to the substrate 5 and the combination of the photoresist film and its upper layer film, for example, Further, visible light, ultraviolet rays such as g-line and i-line, and far ultraviolet rays such as excimer laser may be used. In particular, in the exposure apparatus 1 of the present embodiment, an ArF excimer laser (wavelength 193 nm) or a KrF excimer laser (wavelength 248 nm) can be suitably used.

  As the mask 12 constituting the optical system 3, an exposure mask used in a conventionally known exposure apparatus can be suitably used. The mask 12 may be a reticle disposed in the illumination optical system 11 or the like. The mask 12 used in the exposure apparatus 1 shown in FIG. 1 is held on a mask stage 16 that can move, finely move, and rotate in a predetermined direction for positioning.

  The projection optical system 13 projects and exposes the pattern of the mask 12 onto the substrate 5 at a predetermined projection magnification. For example, the projection optical system 13 is composed of a plurality of optical elements (for example, lenses) disposed inside the lens barrel. A projection optical system can be cited as a preferred example. Further, in the exposure apparatus 1 of the present embodiment, among the optical elements constituting the projection optical system 13, at least the optical element on the substrate 5 side is made of glass such as calcium fluoride (CaF) or quartz (fused silica). It is preferably a parallel flat lens made of a lens and detachably disposed inside the lens barrel. With this configuration, the corrosion resistance of the optical element on the substrate 5 side can be improved, and the optical element on the substrate 5 side can be replaced. Note that the projection optical system 13 used in the exposure apparatus 1 of the present embodiment may be a reduction system with a projection magnification of less than 1, an enlargement system with a projection magnification of more than 1, or a magnification of 1 with a projection magnification of 1. It may be a system.

  The holding means 2 for holding the substrate 5 is configured to be able to move the held substrate 5 in a predetermined direction so that exposure can be sequentially performed for each predetermined region on the substrate 5. It is preferable that a holding unit used in a conventionally known exposure apparatus can be suitably used. The holding means 2 of the exposure apparatus 1 shown in FIG. 1 supports the Z stage 18 that controls the position and tilt angle in the direction (Z-axis direction) that coincides with the optical axis of the exposure light, and supports the Z stage 18. An XY stage 19 that can be driven in a scanning direction (X-axis direction) in which the mask 12 and the substrate 5 move synchronously in a plane perpendicular to the direction, and a direction (Y-axis direction) orthogonal to the scanning direction; And a base 20 for supporting the XY stage 19. The substrate 5 is held on a Z stage 18 by being held by a substrate holder (not shown) that fixes its back surface by suction or the like. Although not shown, the holding means 2 includes a moving mirror and a laser interferometer for measuring the position of the Z stage 18, a stage driving unit for driving the Z stage 18 and the XY stage 19, and the stage. You may have a control part etc. for controlling a drive part etc.

  The Z stage 18 controls the focus position and tilt angle in the Z-axis direction so that the surface on the substrate 5 is adjusted to the image plane of the projection optical system 13 by the autofocus method and autoleveling, and the XY stage 19 is the substrate. 5 is positioned in the X-axis direction and the Y-axis direction. The two-dimensional position and rotation angle of the Z stage 18 are measured by a laser interferometer (not shown) as the position of a movable mirror (not shown), and a control unit (not shown) is based on the obtained measurement result. ) Is sent to a stage drive unit (not shown), and the stage drive unit (not shown) drives the Z stage 18 and the XY stage 19. At the time of exposure, each exposure region on the substrate 5 is sequentially moved stepwise, and the operation of exposing the pattern formed on the mask 12 is repeatedly performed by the step-and-scan method.

  As the substrate 5 used in the exposure apparatus 1 of the present embodiment, a substrate in which a photoresist film is formed by previously applying a photoresist on one surface of the substrate is used. As this substrate, for example, a silicon wafer, a wafer coated with aluminum, or the like can be used. In order to maximize the potential of the photoresist film, an organic or inorganic antireflection film is formed on the surface of the substrate to be used, as disclosed in, for example, Japanese Patent Publication No. 6-12452. You may keep it. In addition, there is no restriction | limiting in particular about the photoresist apply | coated to the board | substrate 5, For example, it can select suitably according to the intended purpose of a resist.

  For example, as described above, the liquid supply unit 4 supplies the liquid 7 to the space 6 between the substrate 5 held by the holding unit 2 and the optical system 3 in parallel with the scanning direction of the substrate 5. And a liquid recovery section 15 that recovers the liquid 7 supplied to the space 6. For example, the liquid supply unit 14 includes a supply tank 21 that stores the liquid 7 and a supply channel 23 that serves as a channel for the supplied liquid 7, and the liquid recovery unit 15 stores the recovered liquid 7. A recovery tank 22 to be recovered, and a recovery flow path 24 to be a flow path of the liquid 7 to be recovered. The liquid 7 is supplied from the liquid supply unit 14 via the supply channel 23 to the space 6 by a predetermined amount per unit time, and similarly, the predetermined amount per unit time is supplied to the liquid recovery unit 15 via the recovery channel 24. Collected. Thereby, the liquid 7 is filled in the space 6 between the front end surface of the projection optical system 13 and the substrate 5. Further, although not shown, the liquid supply unit includes a supply pump for supplying a liquid, a temperature control unit for controlling the temperature of the liquid, and a liquid deaeration for removing dissolved gas contained in the supplied liquid. And a filter for removing impurities such as fine particles contained in the liquid, a function of measuring the remaining amount of the liquid, and a recovery pump for recovering the liquid in the liquid recovery part Alternatively, a temperature control unit that controls the temperature of the liquid or a function of measuring the amount of the recovered liquid may be provided.

  In the exposure apparatus 1 of the present embodiment, the liquid 7 is filled between the surface of the substrate 5 and the optical system 3 (specifically, the tip of the projection optical system 13 (with a diameter of about 50 to 70 mm)). As described above, the lens barrel and a part of the optical element supported by the lens barrel are disposed at the tip of the projection optical system 13, and the liquid 7 is in contact with part of the optical element and part of the lens barrel. The liquid 7 may be subjected to deoxygenation treatment in advance in order to maintain permeability. A liquid having a refractive index larger than that of pure water is desirable. In order to prevent bubbles from appearing in the liquid 7 during use and adversely affecting exposure, the liquid 7 (for example, an organic liquid) is degassed in addition to the deoxygenation immediately before its supply. It is more preferable to remove the gas dissolved in the liquid 7 by the treatment. This is because in the process of manufacturing the liquid 7, an inert gas (nitrogen or the like) may be included in the supersaturation for sealing or the like.

  In the exposure apparatus 1 according to the present embodiment, the tip of the projection optical system 13 is subjected to a surface treatment (coating) according to the affinity with the liquid 7, and the surface of the substrate 5 is also compatible with the liquid 7. Surface treatment (for example, a top coat film) is applied in accordance with the characteristics, and on the other hand, other liquids (for example, the lens barrel portion other than the tip of the projection optical system 13) are non-affinity (hydrophobic) Therefore, the liquid 7 is difficult to escape from the space 6 and is stably held in the space 6. As the material for the surface treatment, a material that is insoluble in the liquid 7 is used. Further, the liquid supply flow path 23 is made of a material that does not contain an eluate with respect to the liquid 7. For example, a Teflon (registered trademark) material or a metal material such as stainless steel is desirable.

  Further, in the exposure apparatus 1 of the present embodiment, the members used in the region in contact with the liquid 7 are made of a conductive material that does not elute into the liquid 7 so as to be electrically grounded. It is configured. For example, the supply channel 23 for supplying the liquid 7, the recovery channel 24 for recovering the liquid, the region for suppressing the scattering of the liquid 7 around the tip of the projection optical system 13 to a region other than the desired region, and the substrate 5 The holding Z stage 18 and the like are configured to be kept at an electrical ground level.

  At the time of exposure performed using the exposure apparatus 1 of the present embodiment, a part of the pattern image of the mask 12 is projected onto the projection area immediately below the tip of the projection optical system 13. With respect to the fixed projection optical system 13, the mask 12 moves (for example) in the −X direction at a predetermined speed, and in synchronization therewith, the substrate 5 projects in the (for example) + X direction via the XY stage 19. The exposure is performed by moving at a predetermined speed in consideration of the magnification. When the exposure of one area is completed, the substrate 5 is moved by a desired amount and moved to the scanning start position of the next area, and similarly, the scanning exposure is sequentially performed (step-and-scan). method). It is desirable that the moving direction of the substrate 5 and the direction in which the liquid 7 flows are parallel to each other.

  Further, in the exposure apparatus 1 of the present embodiment, the position of the tip end region of the projection optical system 13, the supply flow path 23 for supplying the liquid 7 in the X-axis direction, and the recovery flow path 24 for recovering the liquid 7 Although there is no particular limitation on the relationship, the shape of the tip of the projection optical system 13 is an effective exposure region, usually about 33 mm × 26 mm. For example, a supply flow path 23 with a terminal branching in three and a recovery flow path 24 with a terminal branching in two are arranged so as to sandwich the tip of the projection optical system 13 in the X-axis direction. Can be mentioned. The branched supply flow paths 23 are connected to the liquid supply section 14 after being assembled, and the branched recovery flow paths 24 are connected to the liquid recovery section 15 after being collected.

  Further, although not shown in the drawing, the supply flow path and the recovery flow path 24 in FIG. 1 are not shown in the arrangement in which the supply flow path and the recovery flow path are rotated by 180 ° with respect to the center of the tip end portion of the projection optical system 13. For supplying liquid in the opposite direction (the direction from the left to the right in FIG. 1), a second supply channel having three ends and a second branch having two ends. A recovery channel is arranged. The supply channel 23 and the recovery channel 24 in FIG. 1 are alternately arranged in the Y-axis direction, and the second supply channel and the second recovery channel are alternately arranged in the Y-axis direction. The second supply channel is connected to the liquid supply unit 14 in the same manner as the supply channel 23, and the second recovery channel is connected to the liquid recovery unit 15.

  Next, an embodiment of the exposure method of the present invention (second invention) will be described. The exposure method of the present embodiment can be carried out using one embodiment (exposure apparatus 1) of the first invention shown in FIG. Hereinafter, the exposure method of the present embodiment will be described with reference to the exposure apparatus 1 shown in FIG. In the exposure method of the present embodiment, the substrate 5 on which the photoresist film and the upper layer film are arranged is held by the holding means 2 and the exposure light for projecting a predetermined pattern is irradiated from the optical system 3. In this exposure method, a predetermined resist pattern is formed on the substrate 5 by developing the substrate 5, and the predetermined pattern is projected onto the substrate 5 held by the holding means 2 and the substrate 5 held by the holding means. An exposure method for filling the space 6 between the optical system 3 for irradiating the exposure light and the liquid 7 in the space 6 and exposing the substrate 5 through the liquid 7. In this exposure method, the liquid 7 filling the space 6 with the optical system 3 is electrically grounded. As a method of electrically grounding the liquid 7, as shown in FIG. 1, the ground 8 is disposed in the liquid 7 or the liquid supply means 4 for supplying the liquid.

  As described above, according to the exposure method of the present embodiment, for example, static electricity generated when the liquid 7 flows is released by the ground 8, so that it is possible to effectively prevent static electricity from being charged in the liquid 7. Can do. For this reason, the influence of static electricity in the liquid at the time of exposure can be removed, and highly accurate exposure can be realized. In addition, since the occurrence of sparks due to static electricity that may occur during the supply of the liquid or during the recovery of the liquid is prevented, for example, a flammable substance having a low flash point such as an organic solvent is used as the liquid 7. Even if it is, exposure can be performed safely.

  In the exposure method of the present embodiment, a photoresist film is formed by applying a photoresist on the substrate 5 to be exposed before the exposure by the exposure apparatus 1 described above. As this substrate, for example, a silicon wafer, a wafer covered with a conductive film such as an insulator or aluminum can be used.

  Note that the exposure method of the present embodiment is not limited to the local liquid immersion method as shown in FIG. 1, and can also be used in an immersion type exposure method such as a moving pool method and a simmering stage method.

  In the exposure method of the present embodiment, the liquid 7 may be indirectly electrically grounded. For example, the exposure apparatus is in contact with a part of the liquid 7 and has conductivity. An earth may be connected to a part of 1 to ground the liquid 7.

  Hereinafter, the exposure method of the present embodiment will be described more specifically. In the exposure method of the present embodiment, first, the mask 12 is sent to and held on the mask stage 16. On the other hand, the holding means 2 holds the substrate 5 on which a desired resist is applied in advance on the substrate in the form of a film and an upper layer film (top coat film) for blocking the resist and the liquid 7 is formed on the resist as necessary. After the positional relationship and rotation are measured using alignment marks or the like, positioning is performed at a predetermined place.

  Next, the liquid 7 is supplied to the space 6 by the liquid supply unit 14, and at the same time, the liquid 7 is recovered by the liquid recovery unit 15. When the substrate 5 moves in the −X direction (leftward in FIG. 1), the liquid 7 is supplied from the liquid supply unit 14 via the supply flow path 23 and the projection optical system 13 and the substrate 5. And the liquid 7 is recovered by the liquid recovery unit 15 via the recovery flow path 24, and this operation causes the liquid 7 to flow between the tip of the projection optical system 13 (the lower surface of the lens) and the substrate 5. It flows in the −X direction so as to fill the space 6.

  On the other hand, when the substrate 5 moves in the + X direction (the right direction in FIG. 1), the liquid supply unit 14 is not shown in the drawing but passes through the second supply channel branched to the liquid recovery unit 15 side. The liquid 7 is supplied between the projection optical system 13 and the substrate 5, and the liquid 7 is recovered to the liquid recovery unit 15 via the second recovery flow path (not shown). Flows in the + X direction so as to fill the space between the tip of the projection optical system 13 (the lower surface of the lens) and the substrate 5.

  The exposure is performed after a predetermined time has elapsed since the operation for supplying and collecting the liquid 7 was started. In the exposure, the mask 12 is illuminated with exposure light (for example, ArF excimer laser light (wavelength 193 nm)) emitted from the illumination optical system 11, and the substrate 5 (resist (film)) is passed through the projection optical system 13 and the liquid 7. ) The pattern of the mask 12 is transferred. As already described, in the exposure apparatus 1 of the immersion type exposure method, scanning exposure is sequentially performed for each region of the substrate 5 by the step-and-scan method at the time of exposure.

  When exposure of desired positions on all the substrates 5 is finished, first, the liquid supply unit 14 is stopped and the supply of the liquid 7 is stopped. 5) and the liquid recovery unit 15 is stopped. Next, the substrate 5 is collected in a cassette. If necessary, the same process is performed by moving the next substrate to the stage. In this way, the exposure process for all necessary substrates is completed. Finally, the mask 12 is returned to a predetermined accommodation place.

  As described above, in the exposure method of the present embodiment, the liquid 7 is electrically grounded, and the static electricity charged in the liquid 7 is discharged to the outside through the ground 8. It can be suitably used when the liquid 7 that fills the space 6 between the optical system 3 (specifically, the tip of the projection optical system 13) is an organic solvent. Currently, pure water is mainly studied as the liquid 7 that fills the space 6. However, as the pattern to be exposed is further refined, the liquid 7 has a high transmittance at the exposure wavelength of the exposure light and is pure. It is necessary to use a liquid having a sufficiently high refractive index as compared with water. An organic solvent can be given as one of the liquids satisfying such requirements. However, since the organic solvent includes a flammable substance, for example, the liquid 7 exists in a movable part inside the exposure apparatus. Or, if a spark due to static electricity is generated in a region where a volatilized atmosphere exists, there is a fear that the liquid 7 is ignited in the exposure apparatus 1. According to the exposure method of the present embodiment, since the liquid 7 that fills the space 6 between the substrate 5 and the optical system 3 held by the holding unit 2 is electrically grounded, the above-described exposure is performed. Thus, even if an organic solvent is used as the liquid 7, exposure can be performed safely.

  In the exposure method of the present embodiment, the method of electrically grounding the liquid 7 filling the space 6 between the substrate 5 held by the holding means 2 and the optical system 3 is not particularly limited, and the first described above. This can be realized by a method similar to the electrical grounding method described in the exposure apparatus 1 of one embodiment of the present invention. For example, a ground 8 is provided in the liquid supply means 4 for filling the liquid 7 in the space 6 between the substrate 5 and the optical system 3 held by the holding means 2, and the liquid 7 is electrically grounded. As a preferred example, a method of performing electrical contact with the liquid 7 by arranging a ground 8 in the space 6 between the substrate 5 held by the holding means 2 and the optical system 3 is described. be able to.

  As the holding means 2 and the optical system 3 used in the exposure method of the present embodiment, the holding means 2 and the optical system 3 described in the exposure apparatus 1 of the embodiment of the first invention are preferably used. Can be used.

  The exposure method according to the present embodiment is an exposure method in which the liquid 7 passing through the space 6 between the substrate 5 and the optical system 3 held by the holding unit 2 is electrically grounded. 2 may be further electrically grounded. For example, when the exposure apparatus 1 as shown in FIG. 1 is used, the liquid 7 always passes over the substrate 5 held by the holding means 2 when the substrate 5 is actually exposed. Further, by electrically grounding the substrate 5 held by the holding means 2, the effect of removing static electricity charged to the liquid 7 can be improved, and the static electricity charged to the substrate 5 itself is also removed. Therefore, exposure can be performed more safely and accurately.

  Furthermore, in the exposure method according to the present embodiment, the grounding means 2 and / or the optical system 3 disposed relatively close to the liquid 7 may be further electrically grounded. For example, the holding unit 2 and the optical system 3 may be charged when static electricity is generated by driving such as positioning or static electricity generated by the liquid 7 flows. Since the holding means 2 and the optical system 3 constituting the exposure apparatus 1 are disposed relatively close to the liquid 7 as described above, static electricity charged in the holding means 2 and the optical system 3 is exposed to the exposure. If there is an adverse effect or sparks are generated around the holding means 2 or the optical system 3, there is a possibility of jumping to the liquid 7. For this reason, it is preferable to further electrically ground the holding means 2 and / or the optical system 3 from the viewpoint of safety and high accuracy of exposure. In the exposure method of the present embodiment, if the exposure apparatus 1 that actually performs exposure further includes components other than the holding means 2 and the optical system 3, it is possible even for those components. It is preferable to perform electrical grounding as much as possible.

  In particular, many organic solvents are highly volatile liquids. When such a highly volatile liquid is used, the volatile liquid component may diffuse in the exposure apparatus, and not only in the area where the liquid flows but also in the area where the volatile component diffuses. For example, it is preferable to effectively prevent the diffused volatile component from igniting by electrically grounding a site where static electricity is generated or a charged site. For this purpose, as in the exposure apparatus 1 shown in FIG. 2, electrical grounding is performed in an area in the exposure apparatus 1 where static electricity may occur in the transfer part of the wafer and the movable part 25 such as the robot arm. It is preferable to carry out. A wafer carried into the exposure apparatus 1 from the outside has various film structures, and static electricity is expected to be generated in relation to the wafer transfer section. It is preferable to take countermeasures against static electricity in a portion that directly contacts the wafer, such as a robot arm.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
As shown in FIG. 1, the exposure apparatus according to the embodiment includes a holding unit 2 (also referred to as a stage) that supports a substrate 5 on which a resist is applied in advance, a mask 12, a mask stage 16 that supports the mask 12, and a mask 12. An optical system 3 having an illumination optical system 11 that illuminates with exposure light, and a projection optical system 13 that projects and exposes a pattern image of a mask 12 illuminated with exposure light onto a substrate 5 supported by the holding means 2; A liquid supply means 4 for filling the space 6 between the substrate 5 held by the means 2 and the optical system 3 with the liquid 7, and the substrate 5 held by the holding means 2 Is electrically grounded to the liquid 7 filling the space 6 between the optical system 3 and the optical system 3 (specifically, the tip of the projection optical system 13).

  In the exposure apparatus 1 of this embodiment, the pattern formed on the mask 12 is moved on the surface of the photosensitive film (resist) of the substrate 5 while the mask 12 and the substrate 5 are synchronously moved in different directions (reverse directions) in the scanning direction. It is a scanning (scan type) immersion exposure apparatus that performs exposure. In the present embodiment, the direction that coincides with the optical axis of the projection optical system 13 is the Z-axis direction, and the movement direction of the mask 12 and the substrate 5 on the plane perpendicular to the Z-axis direction is the X-axis direction, Z-axis direction, and A direction perpendicular to the Y-axis direction is taken as a Y-axis direction.

  The exposure light emitted from the illumination optical system 11 was ArF excimer laser light (wavelength 193 nm in vacuum). The mask stage 16 supports the mask 12, and the position of the mask 12 on the mask stage 16 is measured in real time by a laser interferometer or the like, and is accurately positioned at a predetermined position. The projection optical system 13 projects and exposes the pattern of the mask 12 onto the substrate 5 at a predetermined projection magnification (for example, a reduction system of 4: 1), and a plurality of optical elements supported by a lens barrel made of stainless steel. It is composed of elements (lenses, mirrors, etc.). The tip of the projection optical system 13 is composed of an optical element and a part of a lens barrel that holds the optical element.

  The holding means 2 supports the substrate 5, and is a linear motion system having a Z stage 18 that holds the substrate 5, an XY stage 19 that supports the Z stage, and a base 20 that supports the XY stage. Yes, it is driven by a drive unit (not shown). By driving the Z stage 18, the position of the substrate 5 held by the Z stage 18 is controlled, and by driving the XY stage 19, the position of the substrate 5 in the XY direction, that is, the projection optical system 13. The position of the plane parallel to the image plane is controlled.

  In the exposure apparatus 1 of the present embodiment, the liquid 7 is filled between the surface of the substrate 5 and the tip of the projection optical system 13 (diameter of about 50 to 70 mm). In the exposure apparatus 1 of the present embodiment, an organic solvent (decalin) is used as the liquid 7.

  The liquid supply unit 4 includes a liquid supply unit 14 and a liquid recovery unit 15, and the liquid supply unit 14 includes a supply tank 21 that stores the liquid 7 and a pressure pump. A liquid 7 is supplied to the space 6. The liquid recovery unit 15 includes a suction pump and a recovery tank 22 that stores the recovered liquid 7, and recovers the liquid 7 in the space 6 via the recovery flow path 24.

  The exposure apparatus 1 according to the present embodiment is configured so that the material in the region in contact with the liquid 7 is made of a conductive material that does not elute into the liquid 7 and is electrically grounded. ing.

  When exposure of the substrate 5 was performed using the exposure apparatus 1 configured as described above, generation of static electricity in the exposure apparatus 1 was suppressed, and it was possible to perform exposure safely and with high accuracy.

  In the exposure apparatus and the exposure method of the present invention, since the liquid that fills the space between the substrate and the optical system held by the holding unit by the liquid supply unit is grounded, Occurrence is suppressed and exposure can be performed safely and with high accuracy. Furthermore, the effect can be further improved by further grounding the movable part in the exposure apparatus in order to suppress the generation of static electricity in the region where the atmosphere diffuses even if the liquid to be used volatilizes. For this reason, when manufacturing a semiconductor element or the like, a stepper type that transfers a reticle pattern as a photomask onto a substrate coated with a photoresist via an optical system (projection optical system), or step-and-step It can be suitably used for scanning exposure.

It is explanatory drawing which shows typically the structure of one Embodiment of the exposure apparatus of this invention (1st invention). It is explanatory drawing which shows typically the structure of other embodiment of the exposure apparatus of this invention (1st invention).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exposure apparatus, 2 ... Holding means, 3 ... Optical system, 4 ... Liquid supply means, 5 ... Substrate, 6 ... Space, 7 ... Liquid, 8 ... Ground, 11 ... Illumination optical system, 12 ... Mask, 13 ... Projection Optical system, 14 ... Liquid supply unit, 15 ... Liquid recovery unit, 16 ... Mask stage, 18 ... Z stage, 19 ... XY stage, 20 ... Base, 21 ... Supply tank, 22 ... Recovery tank, 23 ... Supply flow path 24 ... recovery flow path, 25 ... movable part.

Claims (14)

A holding means for holding the substrate, an optical system for irradiating exposure light for projecting a predetermined pattern onto the substrate held by the holding means, and the substrate and the optical system held by the holding means; An exposure apparatus comprising a liquid supply means for filling the space between the liquids,
An exposure apparatus in which electrical grounding is performed on the liquid filling the space between the substrate and the optical system held by the holding unit.   A liquid supply section for supplying the liquid to the space between the substrate held by the holding means and the optical system; a liquid recovery section for recovering the liquid supplied to the space; The exposure apparatus according to claim 1, wherein at least one of the liquid supply unit and the liquid recovery unit is provided with a ground so that the liquid is electrically grounded.   The exposure according to claim 1 or 2, wherein a ground is disposed in the space between the substrate and the optical system held by the holding means, and the liquid is electrically grounded. apparatus.   The exposure apparatus according to claim 1, wherein the liquid is an organic solvent.   The exposure apparatus according to claim 1, wherein electrical grounding is further performed on the substrate held by the holding unit.   6. The exposure apparatus according to claim 1, wherein the holding unit and / or the optical system is further electrically grounded.   The exposure apparatus according to any one of claims 1 to 6, wherein in the exposure apparatus, electrical grounding is performed at a movable portion at least in a region where a volatile component of the liquid exists. A space between the substrate held by a holding unit and an optical system that irradiates exposure light for projecting a predetermined pattern onto the substrate held by the holding unit is filled with a liquid, and the liquid passes through the liquid. An exposure method for exposing the substrate,
An exposure method for electrically grounding the liquid filling the space between the substrate and the optical system held by the holding means.   The ground is provided in the liquid supply means for filling the liquid in the space between the substrate held by the holding means and the optical system, and the liquid is electrically grounded. 9. The exposure method according to 8.   10. The exposure method according to claim 8, wherein a ground is disposed in the space between the substrate held by the holding unit and the optical system to electrically ground the liquid.   The exposure method according to claim 8, wherein an organic solvent is used as the liquid.   The exposure method according to claim 8, wherein electrical grounding is further performed on the substrate held by the holding unit.   The exposure method according to claim 8, wherein electrical grounding is further performed on the holding unit and / or the optical system.   14. The exposure method according to claim 8, wherein electrical grounding is performed in a region near the space between the substrate and the optical system, at least in a region where the volatile component of the liquid exists.

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