JP2007019392A - Exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure device for suppressing cooling by the evaporation heat of solution. <P>SOLUTION: This exposure device for transferring the image of a pattern through solution on a substrate to carry out the exposure of a substrate is provided with a collector for collecting solution supplied on the substrate, and characterized by arranging a moisture absorption heating element inside the collector. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to an exposure apparatus, and in particular, a so-called liquid that immerses the final surface of a projection optical system and the surface of an object to be exposed in a liquid and exposes the object to be exposed through the projection optical system and the liquid. The present invention relates to an immersion exposure apparatus.

  A projection exposure apparatus that exposes a circuit pattern drawn on a reticle (mask) onto a wafer or the like with a projection optical system has been used in the past, and in recent years, an exposure apparatus that has high resolution and is economical is increasingly required. Yes. Immersion exposure is attracting attention as a means for meeting the demand for high resolution. In immersion exposure, the numerical aperture (NA) of the projection optical system is further increased by making the medium on the wafer side of the projection optical system liquid. The NA of the projection optical system is NA = n · sin θ, where n is the refractive index of the medium, and therefore NA is increased to n by satisfying a medium having a refractive index higher than the refractive index of air (n> 1). be able to. As a result, the resolution R (R = k1 (λ / NA)) of the exposure apparatus expressed by the process constant k1 and the wavelength λ of the light source is to be reduced.

  In immersion exposure, a local fill method has been proposed in which liquid is locally filled between the final surface of the projection optical system and the surface of the wafer (see, for example, Patent Document 1). However, in the local fill method, since the liquid is allowed to flow between the final surface of the projection optical system and the surface of the wafer, it may not flow well. As a result, the liquid that did not flow well collides with the outer periphery of the final lens of the projection optical system and escapes to the outside, resulting in an intermittent liquid flow, so that bubbles enter the liquid. In the immersion exposure, since the wafer is moved at a high speed, the liquid is scattered around and the total amount of the liquid is reduced, so that bubbles are mixed in the liquid. As a result, the exposure light is irregularly reflected by the bubbles, reducing the exposure amount and lowering the throughput.

In order to solve such a problem, a method of confining a liquid with a gas around the final surface of the projection optical system and the surface of the wafer has been proposed (see, for example, Patent Document 2). Thereby, liquid does not scatter from between the final surface of the projection optical system and the surface of the wafer.
Republished patent WO99 / 49504 JP 2004-289126 A

  However, since the immersion exposure apparatus of Patent Document 2 fills the liquid up to the vicinity of the gas recovery port, the gas recovery port sucks the liquid. When liquid and gas are collected simultaneously, the liquid is very easy to evaporate. Further, by supplying the gas from the surroundings, the liquid easily evaporates from the surface of the confined liquid.

  For this reason, not only the temperature of the liquid itself is lowered by the heat of vaporization, but also the wafer surface and the final lens of the photographing optical system are cooled. It was getting worse.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to suppress the influence of temperature change caused by liquid evaporation in an immersion exposure apparatus.

  In the present invention, in an exposure apparatus that exposes the object to be exposed by immersing a liquid between the final lens of the projection optical system and the object to be exposed, the moisture-absorbing exothermic material is used at least in part, and the liquid immersion material is absorbed by moisture. Cooling by the heat of vaporization of the immersion material is suppressed by heat (adsorption heat) generated when the exothermic material absorbs.

  Applicable place of moisture-absorbing heat generation material is approximately the same height as the object to be exposed, and is located near the outer periphery of the object to be exposed (hereinafter referred to as the same surface plate) And a member that forms a recovery port for the immersion material.

  As the hygroscopic exothermic material, a resin alone composed of a polyurethane, polyester, polyamide, silicone polymer or the like as a main component, or a resin composition composed of a mixture thereof can be used.

  ADVANTAGE OF THE INVENTION According to this invention, the exposure apparatus which suppresses the exposure defect accompanying a temperature change can be provided.

  Hereinafter, an exposure apparatus according to one aspect of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted. Here, FIG. 1 is a schematic sectional view showing the structure of the exposure apparatus 1 of the present invention.

  The exposure apparatus 1 includes a circuit formed on the reticle 20 via a liquid (immersion liquid) LW supplied between the final surface (final optical element) on the wafer 40 side of the projection optical system 30 and the wafer 40. It is an immersion type projection exposure apparatus that exposes a pattern onto a wafer 40. Such an exposure apparatus is suitable for a lithography process of submicron or quarter micron or less. The exposure method may be a step-and-scan method or a step-and-repeat method. Hereinafter, in this embodiment, a step-and-scan type exposure apparatus (also referred to as a “scanner”) will be described as an example. Here, the “step and scan method” means that the wafer is continuously scanned (scanned) with respect to the reticle to expose the reticle pattern onto the wafer, and the wafer is stepped after completion of one shot of exposure. The exposure method moves to the next exposure area. The “step-and-repeat method” is an exposure method in which the wafer is stepped and moved to the next exposure area for every batch exposure of the wafer.

  As shown in FIG. 1, the exposure apparatus 1 includes an illumination device 10, a reticle stage 25 on which a reticle 20 is placed, a projection optical system 30, a wafer stage 45 on which a wafer 40 is placed, and a distance measuring device 50. , A stage control unit 60, a medium supply device 70, an immersion control unit 80, a liquid recovery device 90, a lens barrel 100, and the like.

  The illumination device 10 illuminates a reticle 20 on which a transfer circuit pattern is formed, and includes a light source unit 12 and an illumination optical system 14.

  In this embodiment, the light source unit 12 uses an ArF excimer laser having a wavelength of 193 nm as a light source. However, the light source unit 12 is not limited to an ArF excimer laser. For example, a KrF excimer laser having a wavelength of about 248 nm or an F2 laser having a wavelength of about 157 nm may be used, and the number of light sources is not limited. The light source that can be used for the light source unit 12 is not limited to a laser, and one or a plurality of lamps such as a mercury lamp and a xenon lamp can be used.

  The illumination optical system 14 is an optical system that illuminates the reticle 20, and includes a lens, a mirror, an optical integrator, a stop, and the like. For example, a condenser lens, a fly-eye lens, an aperture stop, a condenser lens, a slit, and an imaging optical system are arranged in this order. The optical integrator includes an integrator configured by stacking a fly-eye lens and two sets of cylindrical lens array (or lenticular lens) plates, but may be replaced by an optical rod or a diffractive element.

  The reticle 20 is transported from outside the exposure apparatus 1 by a reticle transport system (not shown), and is supported and driven by the reticle stage 25. The reticle 20 is made of, for example, quartz, and a circuit pattern to be transferred is formed thereon. Diffracted light emitted from the reticle 20 passes through the projection optical system 30 and is projected onto the wafer 40. The reticle 20 and the wafer 40 are arranged in an optically conjugate relationship. Since the exposure apparatus 1 is a scanner, the pattern of the reticle 20 is transferred onto the wafer 40 by scanning the reticle 20 and the wafer 40 at a speed ratio of the reduction magnification ratio. In the case of a step-and-repeat type exposure apparatus (also referred to as “stepper”), exposure is performed with the reticle 20 and the wafer 40 stationary.

  The reticle stage 25 is attached to a surface plate 27 for fixing the reticle stage 25. The reticle stage 25 supports the reticle 20 via a reticle chuck and is controlled to move by a moving mechanism and stage control unit 60 (not shown). A moving mechanism (not shown) is constituted by a linear motor or the like, and can move the reticle 20 by driving the reticle stage 25 in the X-axis direction.

  The projection optical system 30 has a function of forming an image on the wafer 40 of diffracted light that has passed through the pattern formed on the reticle 20. The projection optical system 30 includes an optical system including only a plurality of lens elements, an optical system (catadioptric optical system) having a plurality of lens elements and at least one concave mirror, a plurality of lens elements, and at least one kinoform. An optical system having a diffractive optical element such as can be used. When correction of chromatic aberration is required, a plurality of lens elements made of glass materials having different dispersion values (Abbe values) are used, or the diffractive optical element is configured to generate dispersion in the opposite direction to the lens elements.

  The wafer 40 is transported from the outside of the exposure apparatus 1 by a wafer transport system (not shown), and is supported and driven by the wafer stage 45. The wafer 40 is a wafer in this embodiment, but widely includes a liquid crystal substrate and other objects to be processed. A photoresist is applied to the wafer 40.

  The coplanar plate 44 is a plate configured on substantially the same plane as the wafer 40 and has substantially the same height as the wafer 40. In addition, the same surface plate 44 is preferably used for immersion exposure, and enables a liquid film to be formed in a region outside the wafer 40.

  The wafer stage 45 is mounted on a surface plate 47 and supports the wafer 40 via a wafer chuck (not shown in FIG. 1). The wafer stage 45 has a function of adjusting the position, rotation direction, and tilt of the wafer 40 in the vertical direction (vertical direction), and is controlled by the stage control unit 60. During exposure, the stage controller 60 controls the wafer stage 45 so that the surface of the wafer 40 always matches the focal plane of the projection optical system 30 with high accuracy.

  The distance measuring device 50 measures the position of the reticle stage 25 and the two-dimensional position of the wafer stage 45 via the reference mirrors 52 and 54 and the laser interferometers 56 and 58 in real time. The distance measurement result by the distance measuring device 50 is transmitted to the stage control unit 60, and the reticle stage 25 and the wafer stage 45 are driven at a constant speed ratio under the control of the stage control unit 60 for positioning and synchronization control. Is done. In this way, the stage control unit 60 performs drive control of the reticle stage 25 and the wafer stage 45.

  The medium supply device 70 has a function of supplying the liquid LW to the space or gap between the projection optical system 30 and the wafer 40 and supplying the gas PG around the liquid LW. In this embodiment, the medium supply device 70 includes a generation device (not shown), a deaeration device, a temperature control device, a liquid supply pipe 72, and a gas supply pipe 74. In other words, the medium supply device 70 supplies the liquid LW via the liquid supply pipe 72 and the liquid supply unit arranged around the final surface of the projection optical system 30, and the space between the projection optical system 30 and the wafer 40. A liquid film of liquid LW is formed in the space. Further, the medium supply device 70 supplies the gas PG around the liquid LW through the gas supply pipe 74, forms an air curtain, and suppresses the scattering of the liquid LW. The space between the projection optical system 30 and the wafer 40 is preferably such that the liquid film of the liquid LW can be stably formed and removed, for example, 1.0 mm.

  The medium supply device 70 may include, for example, a tank that stores liquid or gas, a pressure feeding device that sends out liquid or gas, and a flow rate control device that controls the supply flow rate of liquid or gas.

  The liquid LW is selected from those that absorb less exposure light, and preferably has a refractive index that is substantially the same as that of a refractive optical element such as quartz or fluorite. Specifically, pure water, functional water, a fluorinated liquid (for example, fluorocarbon) or the like is used as the liquid LW. In addition, the liquid LW is preferably one in which the dissolved gas is sufficiently removed in advance using a degassing device (not shown). This is because the generation of bubbles is suppressed, and even if bubbles are generated, they can be immediately absorbed into the liquid. For example, if nitrogen and oxygen contained in a large amount in the air are targeted and 80% or more of the gas amount in which the liquid can be dissolved is removed, the generation of bubbles can be sufficiently suppressed. Of course, a degassing device (not shown) may be provided in the exposure apparatus, and the liquid LW may be supplied to the medium supply device 70 while always removing the dissolved gas in the liquid.

  The generating device reduces impurities such as metal ions, fine particles, and organic matter contained in raw water supplied from a raw water supply source (not shown), and generates liquid LW. The liquid LW produced | generated by the production | generation apparatus is supplied to a deaeration apparatus.

  The deaeration device performs a deaeration process on the liquid LW to reduce dissolved oxygen and dissolved nitrogen in the liquid LW. The deaerator is constituted by, for example, a membrane module and a vacuum pump. As the deaeration device, for example, a device is preferable in which a gas-permeable membrane is separated, a liquid is flowed on one side, the other is evacuated, and a dissolved gas in the liquid is expelled into the vacuum through the membrane.

  The temperature control device has a function of controlling the liquid LW to a predetermined temperature.

  The liquid supply pipe 72 supplies the liquid LW, which has been deaerated and temperature-controlled by the deaerator and the temperature controller, to the space between the projection optical system 30 and the wafer 40.

  The liquid supply pipe 72 is preferably made of a resin such as a Teflon (registered trademark) resin, a polyethylene resin, or a polypropylene resin with a small amount of eluted substances so as not to contaminate the liquid LW. When a liquid other than pure water is used as the liquid LW, the liquid supply pipe 72 may be made of a material that is resistant to the liquid LW and has a small amount of eluted substances.

  The gas supply pipe 74 supplies the gas PG from the medium supply device 70 so as to cover the periphery of the liquid LW. The gas supply pipe 74 is made of various resins and metals such as stainless steel.

  The gas PG suppresses the liquid LW from being scattered around the projection optical system 30 and protects the liquid LW from the external environment, and prevents the external gas from being dissolved in the liquid LW. As the predetermined gas PG, an inert gas such as nitrogen, helium, neon, or argon, or hydrogen is used. Thereby, oxygen which has a large influence on exposure can be blocked. Moreover, even if the predetermined gas PG is dissolved in the liquid LW, the influence on exposure can be reduced, and deterioration of the exposed pattern can be prevented.

  The medium recovery device 90 has a function of recovering the liquid LW and gas PG supplied by the medium supply device 70, and includes a liquid recovery pipe 92 and a gas recovery pipe 94. The liquid recovery device 90 includes, for example, a tank that temporarily stores the recovered liquid LW and gas PG, a suction unit that sucks the liquid LW and gas PG, a flow rate control device for controlling the recovery flow rate of the liquid LW and gas PG, and the like. Prepare.

  The liquid recovery pipe 92 recovers the supplied liquid LW. The liquid recovery pipe 92 is preferably made of a resin such as a Teflon (registered trademark) resin, a polyethylene resin, or a polypropylene resin with a small amount of eluted substances so as not to contaminate the liquid LW. When a liquid other than pure water is used as the liquid LW, the liquid recovery pipe 92 may be made of a material that is resistant to the liquid LW and has a small amount of eluted substances.

  The gas recovery pipe 94 recovers the supplied gas PG. The gas recovery pipe 94 is made of various resins or metals such as stainless steel.

  The liquid immersion control unit 80 acquires information such as the current position, speed, acceleration, target position, and moving direction of the wafer stage 45 from the stage control unit 60, and performs control related to liquid immersion exposure based on the information. . The liquid immersion control unit 80 gives the liquid supply device 70 and the liquid recovery device 90 a control command such as switching, stopping, supplying, and recovering the amount of the liquid LW to be supplied and recovered.

  The lens barrel 100 has a function of holding the projection optical system 30.

  A liquid supply port (not shown) is connected to the liquid supply pipe 72, and the liquid supply port is an opening for supplying the liquid LW. The liquid supply port is formed in the vicinity of the projection optical system 30, and a porous body such as a sponge may be fitted into the liquid supply port, or the shape thereof may be a slit-shaped opening.

  A gas supply port (not shown) is connected to the gas supply pipe 72, and the gas supply port is an opening for supplying the gas PG. The gas supply port may be fitted with a porous body such as a sponge, or may be a slit-shaped opening.

  A liquid recovery port (not shown) is connected to the liquid recovery pipe 92 and is an opening for recovering the supplied liquid LW. A porous body such as a sponge may be fitted therein, or the shape thereof is a slit-shaped opening. It may be.

  A gas recovery port (not shown) is connected to the gas recovery pipe 94, and the gas recovery port is an opening for recovering the supplied gas PG. The gas recovery port may be fitted with a porous member such as a sponge, or the shape may be a slit-like opening.

  Further, when the gas supplied to prevent the liquid LW from scattering is dry air or an inert gas that does not contain moisture, the liquid LW easily evaporates, and the wafer 40 is cooled by the influence of the heat of vaporization accompanying evaporation. As the temperature of the wafer 40 decreases, the surface of the wafer 40 is deformed, causing exposure failure.

  In order to suppress evaporation of the liquid LW, generation of a vapor (not shown) for mixing the vapor supplied from the gas supply port with vapor of the same substance as the liquid LW or vapor having the same composition as the vapor generated when the liquid LW is vaporized Gas is supplied to the gas supply port via the apparatus. The maximum amount of vapor mixed is about the saturated vapor pressure, and the amount of mixed vapor can be adjusted.

  With this configuration, it is possible to suppress the evaporation of the liquid LW.

  However, since the atmosphere around the lens barrel 100 is sucked together with the liquid LW from the liquid recovery port and the gas recovery port, the temperature inside the liquid recovery port is lowered.

  FIG. 2 is an enlarged view of the cross section of the recovery port (recovery part). Here, the recovery port refers to the liquid recovery port or the gas recovery port in FIG. 1, but is not limited thereto. An example in which the collection port is configured in another place will be described later.

  A hygroscopic heating element (5, 6) is disposed inside the recovery port. The hygroscopic heating element is made of a hygroscopic exothermic material. As the hygroscopic exothermic material, a resin alone composed of a polyurethane, polyester, polyamide, silicone polymer or the like as a main component, or a resin composition composed of a mixture thereof can be used.

  The hygroscopic heating element 5 is affixed inside the recovery port. When an adhesive is used in the vicinity of the recovery port, the adhesive may be dissolved by the immersion material, and the adhesive that has melted to the outside of the recovery port may leak due to diffusion. Since the leaked adhesive adheres to the optical member and causes deterioration of the transmittance, the hygroscopic heating element 6 is sandwiched by the porous body 7 and is disposed near the inlet of the recovery port.

  The arrangement method of the hygroscopic heating element is not limited to this, and the hygroscopic heating element may be directly arranged, the hygroscopic heating element may be screwed, or the optical member may be melted by an immersion material. It may be attached to the porous body with an adhesive having little deterioration in transmittance even if it adheres to the surface.

  By providing the hygroscopic heating element in this way, the hygroscopic heating element absorbs the liquid and heat (adsorption heat) is generated. This heat generation can suppress the cooling due to the heat of vaporization of the liquid.

  In addition, a recovery port may be disposed in the vicinity of the outer periphery of the wafer in order to suppress liquid from flowing around the wafer back surface. FIG. 3 shows an example in which the recovery port is arranged in a groove formed slightly between the wafer and the same surface plate. If the liquid remains in the groove between the wafer and the same surface plate, the remaining liquid is dried, and the temperature of the outer peripheral portion of the wafer is lowered by the heat of vaporization. In FIG. 3, a recovery port 42 for recovering the liquid remaining in the groove is provided. The configuration of the recovery port 42 is the same as that shown in FIG. Further, the hygroscopic heating element may be provided outside the collection port. In FIG. 3, a hygroscopic heating element 46 is provided in the groove between the wafer and the same surface plate. As described above, by providing the hygroscopic heating element in the vicinity of the outer peripheral portion of the wafer, cooling due to the vaporization heat of the liquid at the outer peripheral portion of the wafer can be suppressed.

  Further, as shown in FIG. 4, the same surface plate 44 may be formed of a porous body, and a recovery port may be provided on the back side of the same surface plate. By doing in this way, the liquid which remained in the same surface board 44 can be collect | recovered via porous. The configuration of the recovery port 43 is the same as that shown in FIG. Further, the hygroscopic heating element may be provided in addition to the inside of the recovery port. Furthermore, in FIG. 4, the moisture absorption heat generating body 47 is provided in the back side of the same surface board. The hygroscopic heating element 47 may be provided on the inner side (wafer side) of the same surface plate.

  In the above description, an example in which a hygroscopic heating element is separately provided has been shown, but it is also possible to use a hygroscopic heating material for a part of the constituent members. For example, a part of the recovery port, the same surface plate, and the wafer chuck may be used as a moisture absorbing heat generating material.

  Further, not only a hygroscopic heating element may be arranged, but a temperature controller such as a heater may be used in combination to suppress cooling due to vaporization heat.

  Further, in this embodiment, an air curtain is formed to suppress the scattering of the liquid LW, and the hygroscopic heat generating material is used. However, even when the air curtain is not used, a part of the liquid recovery port is used. Alternatively, a moisture-absorbing heat generating material may be used for a part of the same surface plate or a part of the member disposed in the vicinity of the outer periphery of the wafer.

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

  Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS. FIG. 5 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, etc.). Here, a semiconductor chip manufacturing method will be described as an example.

  In step S1 (circuit design), a semiconductor device circuit is designed. In step S2 (mask fabrication), a mask is fabricated based on the designed circuit pattern. In step S3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step S4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by using the mask and the wafer by the above-described exposure apparatus using the lithography technique. Step S5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step S4, and an assembly process such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), or the like. including. In step S6 (inspection), the semiconductor device manufactured in step S5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step S7).

  FIG. 6 is a detailed flowchart of the process above Step 4. In step S11 (oxidation), the surface of the wafer is oxidized. In step S12 (CVD), an insulating film is formed on the surface of the wafer. In step S14 (ion implantation), ions are implanted into the wafer. In step S15 (resist process), a photosensitive agent is applied to the wafer. In step S16 (exposure), the circuit pattern of the mask is exposed on the wafer by the exposure apparatus. In step S17 (development), the exposed wafer is developed. In step S18 (etching), portions other than the developed resist image are removed. In step S19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer.

It is the schematic which shows exposure apparatus. It is the schematic which shows a collection port. It is the schematic which shows between a wafer and a same surface board. It is the schematic which shows the example which made the same surface board the porous body. It is a flowchart for demonstrating manufacture of the device using an exposure apparatus. 6 is a detailed flowchart of the wafer process in Step 4 of the flowchart shown in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 4,43,44 Recovery port 5,6,46,47 Hygroscopic heat generating body 7 Porous body 10 Illuminating device 20 Reticle 25 Reticle stage 30 Projection optical system 40 Wafer 45 Wafer stage 48 Wafer chuck 50 Distance measuring device 60 Stage Control unit 70 Medium supply device 80 Immersion control unit 90 Medium recovery device 100 Lens barrel

Claims (7)

  An exposure apparatus for transferring an image of a pattern onto a substrate through a liquid to expose the substrate, comprising a recovery unit for recovering the liquid supplied onto the substrate, and a hygroscopic heating element inside the recovery unit An exposure apparatus that is arranged.   2. The projection unit according to claim 1, further comprising a projection optical system for projecting the pattern onto the substrate, wherein the collection unit is arranged so as to collect a liquid between the substrate and the projection optical system. The exposure apparatus described.   The exposure apparatus according to claim 1, further comprising: a member disposed so as to surround an outer periphery of the substrate, wherein the recovery unit is configured to recover a liquid between the member and the substrate. .   It is disposed so as to surround the outer periphery of the substrate, and includes a member at least partially porous, and the recovery unit is disposed so as to recover the liquid on the member through the porous. The exposure apparatus according to claim 1.   An exposure apparatus for transferring an image of a pattern onto a substrate through a liquid to expose the substrate, comprising a recovery unit for recovering the liquid supplied onto the substrate, and a hygroscopic heating element in the vicinity of the recovery unit An exposure apparatus that is arranged.   An exposure apparatus that exposes a substrate by transferring an image of a pattern onto a substrate through a liquid, wherein at least a part of the exposure apparatus is composed of a hygroscopic material. A device manufacturing method comprising: exposing a substrate using the exposure apparatus according to claim 1; and developing the substrate.

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