JPH10303114A - Immersion aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an immersion aligner which does not cause the deterioration of its image forming performance. SOLUTION: An immersion aligner which is provided with a projection optical system PL which transfers a pattern Pa drawn on a reticle R to the surface of a wafer W and print-transfers the pattern Pa, and in which at least part of the working distance L between the lens surface Pe of the optical system PL closest to the wafer W and the wafer W, is filled up with a liquid LQ which transmits exposing light IL is constituted so that the working distance L may meet a relation, L<=λ/(0.3×|N|) (where, λ and N (1/ deg.C) respectively represent the wavelength of the light IL and the temperature coefficient of the refractive index of the liquid IQ). In addition, the liquid LQ is prepared by adding an additive which reduces the surface tension of pure water or increases the interface activity of the pure water to the pure water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exposure apparatus for printing a pattern drawn on a reticle onto a wafer by a projection optical system, and more particularly to an immersion type exposure apparatus.

[0002]

2. Description of the Related Art The distance between the final lens surface and the image plane of an optical system is called a working distance. The working distance of a projection optical system of a conventional exposure apparatus has been filled with air. This working distance is 10 m due to the intervening auto-focus optical system.
It was usual to take more than m. On the other hand, for a pattern to be transferred to a wafer, miniaturization of the pattern is increasingly desired, and for that purpose, it is necessary to shorten the exposure wavelength or increase the numerical aperture. However, there is a limit to the types of glass materials that can transmit short-wavelength light, so a liquid immersion type exposure device that reduces the exposure pattern by filling the working distance with liquid and increasing the numerical aperture is proposed. Have been.

In an immersion type exposure apparatus, there is a possibility that a refractive index distribution may occur due to a temperature distribution of a liquid interposed in a working distance. Therefore, the following technology has been proposed as a countermeasure against the deterioration of the imaging performance due to the temperature change of the liquid. That is, (a) a technique disclosed in FIG. 3 of U.S. Pat. No. 4,346,164 has been proposed as stabilizing the temperature by a liquid temperature stabilizing mechanism. In order to achieve this, a technique disclosed in Japanese Patent Application Laid-Open No. 6-124873 has been proposed. Japanese Patent Application Laid-Open No. HEI 6-124873 also proposes measuring temperature or refractive index as (i) feedback to temperature control by a liquid temperature monitoring mechanism.

[0004]

However, in (a), no discussion has been made as to how much the temperature should be stabilized without any practical problems. However, it is necessary to control the temperature with an unprecedented precision. Regarding item (i), it is difficult to say that it is an effective countermeasure in consideration of the fact that the temperature of the liquid has the greatest influence on the imaging performance. As described above, in the conventionally known technology relating to the immersion type exposure apparatus, there is no example that mentions the constraint on the optical parameter itself of the projection optical system such as the working distance, and the special circumstances of the immersion type are considered. I could not say it. Therefore, an object of the present invention is to provide a liquid immersion type exposure apparatus which facilitates temperature control of a liquid satisfying a working distance and does not cause deterioration of imaging performance.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. That is, the present invention has a projection optical system for printing and transferring a pattern drawn on a reticle onto a wafer. In a liquid immersion type exposure apparatus in which at least a part of the working distance between the lens surface and the wafer closest to the wafer of the optical system is filled with a liquid that transmits exposure light, the length of the working distance is L, When the wavelength of the exposure light is λ and the temperature coefficient of the refractive index of the liquid is N (1 / ° C.), it is characterized in that L ≦ λ / (0.3 × | N |). A liquid immersion type exposure apparatus, wherein a liquid obtained by adding an additive for reducing the surface tension of pure water or increasing the surface activity of pure water to pure water is used as the liquid. This is an immersion exposure apparatus.

The operation of the present invention will be described below. The distance from the glass surface at the tip of the projection optical system to the imaging surface, that is, the working distance is L, the width of the temperature distribution of the medium satisfying the working distance L is ΔT, and the aberration of the imaging wavefront caused by this temperature distribution ΔT Is ΔF and the temperature coefficient of the refractive index of the liquid is N, the following formula (1) is approximately established. ΔF = L × | N | × ΔT (1)

Regarding the temperature distribution ΔT of the medium, no matter how much the temperature distribution ΔT is controlled to achieve the uniformity, ΔT =
It is assumed that a temperature distribution of about 0.01 ° C. exists. Therefore, the imaging wavefront aberration ΔF has at least ΔF = L × | N | × 0.01 (1a). Here, N is 1 / the temperature coefficient of the refractive index.
It is a value expressed in ° C.

The value of the temperature coefficient N of the refractive index greatly differs between liquid and gas. For example, N = -9 × 10 ⁻⁷ / ° C. for air, whereas N = −8 × 10 ⁻ for water. ⁵ / ° C, with a difference of nearly 100 times. On the other hand, the working distance L of the projection optical system of the reduction projection exposure apparatus is usually L> 1.
Although it is 0 mm, even if L = 10 mm, the imaging wavefront aberration ΔF is as follows. Air: ΔF = 10 mm × | -9 × 10 ^{−7 /} ° C. | × 0.01 ° C. = 0.09 nm Water: ΔF = 10 mm × | −8 × 10 ^{−5 /} ° C. ×× 0.01 ° C. = 8.0 nm

However, in general, it is desirable that the imaging wavefront aberration ΔF is not more than 1/30 of the exposure wavelength λ, that is, it is preferable that ΔF ≦ λ / 30 (2) is satisfied. For example, A having a wavelength of 193 nm
When using an rF excimer laser as exposure light,
ΔF <6.4 nm is desirable. When the medium that satisfies the working distance is water, if the working distance L is L> 10 mm as in the prior art, the amount of imaging wavefront aberration due to the temperature distribution of the medium is too large, which may cause a practical problem. I understand.

From the equations (1a) and (2), L ≦ λ / (0.3 × | N |) ‥‥ (3) is obtained. Therefore, by satisfying the expression (3), the amount of wavefront aberration generated by the temperature distribution in the immersion liquid can be reduced to １ ／ of the exposure wavelength under the achievable temperature stability (temperature distribution).
An immersion type exposure apparatus equipped with a projection optical system suppressed to 0 or less can be obtained. As described above, in the present invention, focusing on the fact that the amount of wavefront aberration generated by exposure light passing through a medium having a temperature distribution depends on the product of the amount of temperature distribution and the optical path length in the medium, By providing an upper limit for the optical path length, the requirements for the temperature distribution are eased. Thus, the immersion type exposure apparatus can be put to practical use under the control of the immersion liquid temperature at a achievable level.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below.

[0012]

FIG. 1 shows the overall configuration of a projection exposure apparatus according to a first embodiment of the present invention. Here, a circular image field which is telecentric on both the object side and the image side is shown. Projection lens system PL having
2 shows a lens-scan type projection exposure apparatus that performs relative scanning of the reticle R and the wafer W with respect to the projection lens system PL while projecting a circuit pattern on the reticle R onto the semiconductor wafer W through the semiconductor wafer W. In FIG. 1, an illumination system 10 includes an ArF excimer laser light source (not shown) that emits pulse light having a wavelength of 193 nm, a beam expander (not shown) that shapes a cross-sectional shape of the pulse light from the light source, and the shaped pulse. An optical integrator (not shown) such as a fly-eye lens or the like that generates a secondary light source image (a collection of a plurality of point light sources) upon incidence of light, and pulse illumination from the secondary light source image with a uniform illuminance distribution A reticle blind (illumination field stop) that forms a condensing lens system (not shown) that converts light into light, and shapes the shape of the pulsed illumination light into a rectangle that is long in the direction (X direction) orthogonal to the scanning direction (Y direction) during scanning exposure. , Not shown), and the pulsed light IL from the rectangular opening of the reticle blind is supplied to the condenser lens system 12 in FIG.
A relay optical system (not shown) for forming an image as a slit-shaped or rectangular illumination area AI on the reticle R in cooperation with the mirror 14 is included.

The reticle R is vacuum-adsorbed (in some cases, electrostatically adsorbed or mechanically fastened) on a reticle stage 16 that can move in a one-dimensional direction at a constant speed with a large stroke during scanning exposure. The reticle stage 16 is positioned on the column structure 19 of the apparatus main body in FIG.
The scanning is guided so as to move in the direction (X direction) perpendicular to the plane of the drawing. The coordinate position and minute rotation amount of the reticle stage 16 in the XY plane are determined by projecting a laser beam onto a moving mirror (plane mirror or corner mirror) MRr attached to a part of the reticle stage 16 and receiving the reflected beam. Are sequentially measured by the laser interferometer system 17. The reticle stage controller 20 controls a motor 18 such as a linear motor or a voice coil for driving the reticle stage 16 based on the XY coordinate position measured by the interferometer system 17, and controls the reticle stage 16 in the scan direction. The movement and the movement in the non-scan direction are controlled.

When the rectangular pulse illumination light IL emitted from the condenser lens system 12 and the mirror 14 irradiates a part of the circuit pattern area on the reticle R, the light from the pattern existing in the illumination area AI is formed. Image light flux is 1 /
The image is projected onto a sensitive resist layer applied to the surface of the wafer W through a 4 × reduction projection lens system PL. The optical axis AX of the projection lens system PL is arranged so as to pass through the center point of the circular image field and to be coaxial with each optical axis of the illumination system 10 and the condenser lens system 12.
The projection lens system PL is composed of a plurality of lens elements made of two types of glass materials, quartz and fluorite, which have a high transmittance for ultraviolet light having a wavelength of 193 nm. Fluorite mainly has a positive power. Used for holding lens elements. Further, the inside of a lens barrel for fixing a plurality of lens elements of the projection lens system PL is:
It has been replaced with nitrogen gas in order to avoid absorption of pulsed illumination light of wavelength 193 nm by oxygen. Such replacement with nitrogen gas is similarly performed on the optical path from inside the illumination system 10 to the condenser lens system 12 (or the mirror 14).

Incidentally, the wafer W is held on a holder table WH which sucks the rear surface thereof. A wall portion LB is provided at a constant height over the entire outer peripheral portion of the holder table WH, and the inside of the wall portion LB is filled with a liquid LQ at a predetermined depth. Then, the wafer W is placed on the holder table WH.
Is vacuum-sucked in the recess at the inner bottom. An annular auxiliary plate portion HRS is provided around the inner bottom portion of the holder table WH so as to surround the outer periphery of the wafer W with a predetermined width. The height of the surface of the auxiliary plate portion HRS is determined so as to substantially match the height of the surface of the standard wafer W sucked on the holder table WH.

The main function of the auxiliary plate portion HRS is to be used as an alternative focus detection surface when the detection point of the focus / leveling sensor is located outside the outer edge of the wafer W. The auxiliary plate portion HRS is used to calibrate an alignment sensor used when the shot area on the wafer W is relatively aligned with the circuit pattern on the reticle R, and to use a focus used when scanning and exposing the shot area.・ Can be used for leveling sensor calibration. However, for calibration of the alignment sensor and the focus / leveling sensor, it is preferable to use a dedicated reference mark plate provided separately from the auxiliary plate portion HRS. In this case, the reference mark plate is also mounted on the holder table WH so as to be substantially at the same height as the projection image plane of the projection lens system PL in the liquid immersion state, and the alignment sensor is provided on the various reference marks formed on the reference mark plate. The reference mark is detected in the state of immersion. In addition,
An example of a method of calibrating a system offset of a focus sensor using a reference mark plate on a table is disclosed in, for example, US Pat. No. 4,650,983. An example of a method of calibrating various alignment sensors is described in, for example, US Pat. It is disclosed in Japanese Patent No. 5,243,195.

As shown in FIG. 1, in this embodiment, the tip of the projection lens system PL is immersed in the liquid LQ.
At least the tip is waterproofed so that liquid does not permeate into the lens barrel. Further, the lower surface (the surface facing the wafer W) of the lens element at the tip of the projection lens system PL is processed into a flat surface or a convex surface having an extremely large radius of curvature, whereby the lower surface of the lens element and the surface of the wafer W are exposed during scanning exposure. And the flow of the liquid LQ generated between them can be made smooth. Further, in the present embodiment, as will be described later in detail, the best imaging plane (reticle conjugate plane) of the projection lens system PL in the liquid immersion state is formed at a position of about 2 to 1 mm from the lower surface of the tip lens element. It is designed to be.
Accordingly, the thickness of the liquid layer formed between the lower surface of the front lens element and the surface of the wafer W is also about 2-1 mm,
Thereby, the control accuracy of the temperature adjustment of the liquid LQ is relaxed, and the occurrence of temperature distribution unevenness in the liquid layer can be suppressed.

The holder table WH translates the projection lens system PL in the Z direction along the optical axis AX (coarse movement and fine movement in this embodiment), and tilts slightly with respect to an XY plane perpendicular to the optical axis AX. Is mounted on the XY stage 34 so that The XY stage 34 moves two-dimensionally on the base platen 30 in the XY directions, and the holder table WH
Is mounted on an XY stage 34 via three actuators 32A, 32B and 32C for the Z direction. Each of the actuators 32A, 32B and 32C includes a piezo expansion / contraction element, a voice coil motor, a combination mechanism of a DC motor and a lift cam, and the like. When the three Z actuators are driven in the Z direction by the same amount, the holder table W
H can be translated in the Z direction (focus direction).
By driving the holder table WH in the direction, the tilt direction of the holder table WH and the amount thereof can be adjusted.

The two-dimensional movement of the XY stage 34 is as follows.
The driving is performed by a drive motor 36 configured by a DC motor that rotates a feed screw, a linear motor that generates thrust in a non-contact manner, or the like. The control of the drive motor 36 is performed by the laser interferometer 3 that measures each position change in the X and Y directions of the reflection surface of the movable mirror MRw fixed to the end of the holder table WH.
The measurement is performed by the wafer stage controller 35 which inputs the measurement coordinate position from Step 3. As the overall configuration of the XY stage 34 using the drive motor 36 as a linear motor, for example, the configuration disclosed in Japanese Patent Application Laid-Open No. H8-233964 may be used.

In this embodiment, the working distance of the projection lens system PL is small, and the liquid LQ is filled in a narrow space of about 2 to 1 mm between the lens element at the tip of the projection lens PL and the wafer W. It is difficult to project the light beam of the incident light type focus sensor obliquely onto the wafer surface corresponding to the projection field of view of the projection lens system PL. For this reason, in the present embodiment, as shown in FIG. 1, a focus leveling detection system of the off-axis system (a system having no focus detection point in the projection field of view of the projection lens system PL) and an off-axis system on the wafer W A focus detection system including a mark detection system for detecting alignment marks.
The alignment sensor FAD is arranged around the lower end of the lens barrel of the projection lens system PL.

This focus / alignment sensor F
The lower surface of the optical element (lens, glass plate, prism, etc.) attached to the tip of the AD is, as shown in FIG.
An illumination beam for alignment and a beam for focus detection are radiated from the optical element onto the surface of the wafer W (or the auxiliary plate portion HRS) through the liquid LQ. The focus / leveling detection system outputs a focus signal Sf corresponding to a position error of the surface of the wafer W with respect to the best image plane, and the mark detection system analyzes a photoelectric signal corresponding to an optical characteristic of a mark on the wafer W. Then, an alignment signal Sa indicating the XY position of the mark or the amount of displacement is output.

The above focus signal Sf and alignment signal Sa are sent to the main controller 40, and the main controller 4
0 sends to the wafer stage controller 35 information for optimally driving each of the three Z actuators 32A, B and C based on the focus signal Sf. Accordingly, the wafer stage controller 35 controls the Z actuators 32A, 32B, and 32C such that focus adjustment and tilt adjustment are performed on a region on the wafer W to be actually projected.

The main controller 40 also controls the alignment signal S
Based on “a”, the coordinate position of the XY stage 34 for matching the relative positional relationship between the reticle R and the wafer W is managed. Further, when scanning and exposing each shot area on wafer W, reticle R is moved so that reticle R and wafer W move at a constant speed in the Y direction at a speed ratio equal to the projection magnification of projection lens system PL. The stage controller 20 and the wafer stage controller 35 are controlled synchronously.

Although the focus / alignment sensor FAD in FIG. 1 is provided only at one location around the distal end of the projection lens system PL, two focus alignment sensors FAD are provided in the Y direction across the distal end of the projection lens system PL. , 2 places in the X direction, a total of 4
It is good to provide it at a location. Also, above the reticle R in FIG. 1, an alignment mark formed on the periphery of the reticle R and an alignment mark on the wafer W (or a reference mark on a reference mark plate) are projected lens system PL. (Through-the-reticle) type alignment sensor 45 for detecting the positional deviation between the reticle R and the wafer W with high accuracy by simultaneously detecting the positions of the reticle R and the wafer W. The displacement measurement signal from the TTR alignment sensor 45 is sent to the main controller 40 and used for positioning the reticle stage 16 and the XY stage 34.

The exposure apparatus shown in FIG. 1 performs scanning exposure by moving the XY stage 34 at a constant speed in the Y direction. The exposure apparatus scans the reticle R and the wafer W during the scanning exposure in a stepwise manner. The schedule will be described with reference to FIG. 2, the projection lens system PL in FIG.
Is representatively represented by a front lens group LGa and a rear lens group LGb, and the exit pupil Ep of the projection lens system PL exists between the front lens group LGa and the rear lens group LGb. I do. The reticle R shown in FIG. 2 includes a circuit pattern area Pa having a diagonal length larger than the diameter of the circular image field on the object side of the projection lens system PL.
It is formed on the inside defined by the light shielding band SB.

In the area Pa on the reticle R, the wafer W is scanned and moved at a constant speed Vw in the positive direction along the Y-axis while the reticle R is scanned and moved at a constant speed Vr in the negative direction along the Y-axis, for example. As a result, the corresponding shot area SAa on the wafer W is scanned and exposed.
At this time, the area AI of the pulse illumination light IL that illuminates the reticle R is set in a parallel slit shape or a rectangular shape extending in the X direction within the area Pa on the reticle as shown in FIG. Both ends are located on the light-shielding band SB.

The partial pattern included in the pulse light illumination area AI in the area Pa on the reticle R is located at a corresponding position in the shot area SAa on the wafer W by the projection lens system PL (lens systems LGa, LGb). The image is formed as an image SI. When the relative scanning between the pattern area Pa on the reticle R and the shot area SAa on the wafer W is completed, the wafer W is moved to, for example, the scanning start position for the shot area SAb next to the shot area SAa.
Stepping is performed in the Y direction by a fixed amount. During this step movement, the irradiation of the pulse illumination light IL is interrupted. Next, the image of the pattern in the area Pa of the reticle R is displayed on the wafer W.
The reticle R is moved in the positive Y-axis direction at a constant velocity Vr with respect to the pulse light illumination area AI so that the wafer W is moved in the Y-axis direction with respect to the projection image SI so that the upper shot area SAb is scanned and exposed. By moving in the negative direction at a constant speed Vw, a pattern image of an electronic circuit is formed on the shot area SAb. An example of a technique using pulse light from an excimer laser light source for scanning exposure is described in, for example, US Pat.
No. 24,257.

In the projection exposure apparatus shown in FIGS. 1 and 2, when the diagonal length of the circuit pattern area on the reticle R is smaller than the diameter of the circular image field of the projection lens system PL, the reticle blind in the illumination system 10 is used. By changing the shape and size of the opening to match the shape of the illumination area AI with the circuit pattern area, the apparatus shown in FIG. 1 can be used as a step-and-repeat type stepper. In this case, while the shot area on wafer W is being exposed, reticle stage 16 and XY stage 34 are kept relatively stationary. However, when the wafer W slightly moves during the exposure, the fine movement is measured by the laser interferometer system 33, and the reticle R is corrected so that the minute displacement of the wafer W with respect to the projection lens system PL is tracked on the reticle R side. The stage 16 may be finely controlled.
When changing the shape and size of the reticle blind opening, a zoom lens that concentrates the pulsed light from the light source that reaches the reticle blind in a range that matches the adjusted opening according to the change in the opening shape and size A system may be provided.

As apparent from FIG. 2, the projected image S
Since the region I is set in a slit shape or a rectangular shape extending in the X direction, the tilt adjustment during scanning exposure is performed in the present embodiment exclusively in the rotation direction around the Y axis, that is, in the rolling direction with respect to the scanning exposure direction. Only done in. Of course, when the width of the region of the projection image SI in the scanning direction is large and the influence of flatness on the scanning direction of the wafer surface must be considered, the tilt adjustment in the rotation direction around the X axis, that is, the pitching direction is also required. Performed during scanning exposure.

Here, the state of the liquid LQ in the holder table WH, which is a feature of the exposure apparatus according to the present embodiment, will be described.
This will be described with reference to FIG. FIG. 3 shows a partial cross section from the tip of the projection lens system PL to the holder table WH. A positive lens element LE1 having a flat lower surface Pe and a convex upper surface is fixed to the distal end of the projection lens system PL in the lens barrel. The lower surface Pe of the lens element LE1 is processed (flash surface processing) so as to be flush with the end surface of the distal end portion of the lens barrel, thereby suppressing disturbance of the flow of the liquid LQ. Further, the liquid L at the tip of the lens barrel of the projection lens system PL
The outer peripheral corner 114 immersed in the Q is chamfered with a large curvature as shown in FIG. 3, for example, to reduce the resistance to the flow of the liquid LQ and suppress the generation of unnecessary vortices and turbulence.
At the center of the inner bottom of the holder table WH, a plurality of protruding suction surfaces 113 for vacuum suction of the back surface of the wafer W are formed. The suction surface 113 is specifically 1 mm
It is formed as a plurality of orbicular land portions formed concentrically at a predetermined pitch in the radial direction of the wafer W at approximately the same height.
Each of the grooves engraved at the center of each orbicular land portion is connected to a pipe 112 connected to a vacuum source for vacuum suction inside the table WH.

In this embodiment, as shown in FIG.
Lower surface Pe of lens element LE1 at the tip of projection lens system PL
The distance L between the wafer and the surface of the wafer W (or the auxiliary plate portion HRS) in the best focus state is set to about 2-1 mm. Therefore, the depth Hq of the liquid LQ filled in the holder table WH may be about 2 to 3 times or more the distance L, and therefore, the height of the wall portion LB erected around the holder table WH. May be about several mm to 10 mm. As described above, in the present embodiment, since the interval L as the working distance of the projection lens system PL is extremely small, the total amount of the liquid LQ filled in the holder table WH can be small, and the temperature control can be easily performed.

Here, as the liquid LQ used in this embodiment, pure water that is easily available and easy to handle is used. However, in this embodiment, in order to reduce the surface tension of the liquid LQ and increase the surface active force, the fat which does not dissolve the resist layer of the wafer W and has negligible effect on the optical coat of the lower surface Pe of the lens element is used. Add a group-based additive (liquid) in a small proportion. As the additive, methyl alcohol having a refractive index substantially equal to that of pure water is preferable. In this way, even if the methyl alcohol component in pure water evaporates and its content changes, an advantage is obtained that the change in the refractive index of the liquid LQ as a whole can be extremely small.

The temperature of the liquid LQ is controlled with a certain accuracy with respect to a certain target temperature, but the accuracy with which the temperature can be relatively easily controlled at present is about ± 0.01 ° C. Therefore, let us consider a realistic immersion projection method under such temperature control accuracy. Temperature coefficient of the refractive index of the general air N _a is about -9 × 1
0 ⁻⁷ / ° C., and the temperature coefficient N _q of the refractive index of water is about −8 ×
10 ⁻⁵ / ° C., and the temperature coefficient N _q of the refractive index of water is 2
The order of magnitude is large. On the other hand, assuming that the working distance is L, the wavefront aberration amount ΔF of the image formed due to the temperature change (temperature unevenness) ΔT of the medium satisfying the working distance L is approximately expressed by the following equation. ΔF = L · | N | · ΔT

Here, in the case of normal projection exposure to which the immersion projection method is not applied, the working distance L is 10 mm,
Wavefront aberration Δ when temperature change ΔT is 0.01 ° C
F _air is as follows. ΔF _air = L · | N _a | · ΔT ≒ 0.09 nm Under the same working distance L and temperature change ΔT, the wavefront aberration ΔF _lq obtained by applying the immersion projection method is as follows: Become. ΔF _lq = L · | N _q | · ΔT ≒ 8 nm

This wavefront aberration amount is generally equal to one of the used wavelength λ.
/ 30 or 1/50 to 1/100 is desirable, so that the maximum amount of wavefront aberration ΔF _max allowed when an ArF excimer laser is used is λ / 30 or λ / 50 to λ / 100. 6.43 or 3.
86 to 1.93 nm, preferably λ / 100
Of 1.93 nm or less. By the way, each thermal conductivity at 0 ° C. of air and water is 0.0241 W / m in air.
K, 0.561 W / mK in water, water has better heat conduction, and the temperature unevenness in the optical path formed in water can be made smaller than that in air, resulting in liquid. Fluctuations in the refractive index can also be reduced. However, as shown in Expression (3), the working distance L is 10
mm, the generated wavefront aberration ΔF _lq is equal to the allowable aberration ΔF even if the temperature change ΔT is 0.01 ° C.
_It greatly exceeds _max .

Therefore, from the above considerations, the allowable wavefront aberration Δ
Relationship between the temperature change amount [Delta] T and the working distance L in consideration of F _{max is, ΔF max = λ / 30 ≧} L · | N q | · ΔT _{or, ΔF max = λ / 100 ≧} L · | N q | · ΔT Becomes Here, the assumed temperature change amount ΔT is 0.01
° C., and the wavelength lambda 193 nm, and a refractive index change amount N _q of the liquid LQ to -8 × 10 ^-5 / ℃, the working distance is required (thickness of the liquid layer) L is, 8 mm or 2.4mm or less Becomes Desirably, the working distance L is smaller than 2 mm within a range in which the liquid LQ flows smoothly. With the configuration as in the present embodiment as described above, the temperature control of the liquid LQ is facilitated, and the deterioration of the projected image caused by the wavefront aberration change caused by the temperature change in the liquid layer is suppressed. The pattern of the reticle R can be projected and exposed with the resolving power.

[0037]

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the first
A method of controlling the temperature of the liquid LQ and a method of handling the liquid LQ when exchanging the wafer W, which are also applicable to the third embodiment, will be described.
Therefore, in FIG. 4, the same members as those in FIGS. 1 and 3 are denoted by the same reference numerals. Now, in FIG. 4, a plurality of suction surfaces 113 are formed on the wafer mounting portion formed as a circular concave portion on the inner bottom portion of the holder table WH. Around the circular wafer mounting portion, a groove 51 used for supplying and discharging the liquid LQ is formed in an annular shape.
A part of 1 is connected to an external pipe 53 via a passage 52 formed in the table WH. A temperature controller 50 such as a Peltier device is provided immediately below the wafer mounting portion and directly below the auxiliary plate portion HRS in the holder table WH.
A and 50B are embedded, and a temperature sensor 55 is attached at an appropriate position (preferably at a plurality of positions) on the holder table WH, and the temperature of the liquid LQ is accurately detected.
The temperature controllers 50A and 50B are provided with a temperature sensor 55.
Is controlled by the controller 60 such that the temperature of the liquid LQ detected by the controller becomes a constant value.

On the other hand, the pipe 53 is connected to the switching valve 62.
Are connected to the liquid supply unit 64 and the discharge pump 66 via the. The switching valve 62 responds to a command from the controller 60 to switch the liquid L from the liquid supply unit 64.
An operation is performed to switch between a flow path for supplying Q to the pipe 53 and a flow path for returning the liquid LQ from the pipe 53 to the supply unit 64 via the discharge pump 66. In the supply unit 64, a reserve tank (not shown) capable of storing the entire liquid LQ on the holder table WH, a pump 64A for supplying the liquid LQ from this tank, and a pump 6A
A temperature controller 64B for maintaining the entire liquid LQ in the tank including the 4A at a constant temperature is provided. Further, in the above configuration, the operations of the valve 62, the pump 64A, the temperature controller 64B, and the discharge pump 66 are controlled by the controller 60 as a whole.

Now, in such a configuration, the wafer W
Is transported onto the mounting portion of the holder table WH and mounted on the plurality of suction surfaces 113 in a pre-aligned state, and is fixed under reduced pressure via the vacuum suction pipe 112 shown in FIG. . During this time, the temperature controllers 50A and 50B
It is being controlled to the target temperature. And the wafer W
Is completed, the switching valve 62 is switched from the closed position to the supply unit 64 side, and the temperature-adjusted liquid LQ is supplied to the wall of the holder table WH via the pipe 53, the passage 52, and the groove 51 by the operation of the pump 64A. The switching valve 62 is returned to the closed position by being injected into the portion LB by a fixed amount. Thereafter, when the exposure of the wafer W is completed, the switching valve 62 is immediately switched from the closed position to the discharge pump 66 side, and the liquid LQ on the table WH is moved by the operation of the discharge pump 66 to the groove 5.
1. It is returned into the reserve tank of the supply unit 64 via the pipe 53. Liquid LQ returned to the tank
Is precisely controlled by the temperature controller 64B based on the detection signal from the temperature sensor in the reserve tank until the next wafer is ready.

As described above, according to this embodiment, the liquid LQ during the immersion exposure is supplied to the temperature controller 50 in the holder table WH.
The temperature is controlled by A and 50B, and during the wafer exchange operation, the liquid LQ is collected in the supply unit 64 and the temperature is controlled. Therefore, the wafer exchange becomes possible in the atmosphere and a large change in the temperature of the liquid LQ occurs. There is an advantage that it can be prevented. Further, according to the present embodiment, even if the liquid LQ injected into the holder table WH after the wafer exchange is slightly different from the set temperature (for example, about 0.5 ° C.), the liquid layer depth Hq Since (see FIG. 3) is generally shallow, the set temperature can be reached relatively quickly, so that the time for waiting for temperature stabilization can be shortened.

[0041]

Next, a third embodiment will be described with reference to FIG.
This will be described with reference to FIG. FIG. 5 shows a partial cross section of a holder table WH obtained by improving the configuration of FIG. 3 described above. The holder table WH of this embodiment includes a wafer chuck 90 for holding a wafer W, a Z-direction movement for focus / leveling, and It is divided into a ZL stage 82 that performs tilt movement,
A wafer chuck 90 is mounted on the ZL stage 82. The ZL stage 82 is provided on the XY stage 34 via three Z actuators 32A and 32C (32B is omitted). And in the chuck 90,
1, 3 and 4, the wall LB and the auxiliary plate HR
S, passages 53A and 5 connected to a pipe 112 for vacuum suction and a pipe 53 for supplying and discharging the liquid LQ (see FIG. 4).
3B are respectively formed. However, the passage 53A is connected to the peripheral portion of the auxiliary plate portion HRS inside the wafer chuck 90, and the passage 53B is connected to the wafer chuck 9
0 is connected to the lowest part of the wafer mounting part at the bottom. By forming passages for liquid discharge and injection at a plurality of locations in the wafer chuck 90 in this manner, the liquid can be quickly taken in and out.

Further, in this embodiment, three (only two are shown) through holes 91 are formed in the center portion of the chuck 90, and three (only two are shown) are vertically moved through the through holes 91.
The center-up pin 83 is provided on the vertical drive mechanism 85. The vertical drive mechanism 85 is fixed to the XY stage 34 side. The three center-up pins 83 allow the wafer W on the chuck 90 to be
Is lifted from the mounting surface by a fixed amount or the wafer W is lowered on the mounting surface. When the wafer W is vacuum-sucked on the mounting surface of the chuck 90, as shown in FIG. The tip surface of the center up pin 83 is set at a position lower than the mounting surface of the chuck 90.

On the other hand, the projection lens system P used in this embodiment
At the distal end of L, a parallel flat plate CG made of quartz fixed to the distal end of the sub-barrel 80 in a direction perpendicular to the optical axis AX is attached, so that the lens element LE1 (plano-convex lens) at the distal end is
It is configured not to be immersed in Q. In this embodiment, the distance between the lower surface of the parallel flat plate CG and the surface of the wafer W is an apparent working distance, and is set to 2 mm or less as in the previous embodiment. The mounting surface of the sub-barrel 80 with the parallel flat plate CG is waterproofed, and the inside of the sub-barrel 80 is filled with nitrogen gas.

When the parallel flat plate CG is provided at the tip of the projection lens system PL, the substantial back focus distance (the distance from the tip optical element having refractive power to the image plane) of the projection lens system PL is reduced. Even when the distance is about 10 to 15 mm, it is possible to easily realize the immersion projection method in which the working distance L is set to about 1 to 2 mm to reduce the influence of the temperature change of the liquid. In addition, since the parallel plate CG can be provided later, a part of the surface of the parallel plate CG is polished to the order of a fraction of the wavelength, so that a local micro-distortion generated in the projected image is obtained. (Or random distortion) can be easily corrected. That is, the parallel flat plate CG has both a function as a window for protecting the most advanced lens element of the projection lens system PL from liquid and a function as a distortion correction plate. From another point of view, since the imaging performance of the projection lens system PL including the parallel plate CG is guaranteed, the parallel plate CG is still the most advanced optical element of the projection lens system PL. .

[0045]

Next, a fourth embodiment of the present invention will be described with reference to FIG. This embodiment is related to the embodiment shown in FIG. 5, and relates to a wafer exchange when a projection optical system having a very small working distance is used for an immersion projection exposure method. In FIG.
A reference mirror ML (for the X direction and for the Y direction) that receives and reflects the reference beam BSr from the laser interferometer 33 shown in FIG. 1 is fixed to the lower end of the lens barrel of the projection lens system PL. . And the beam B for length measurement from the laser interferometer 33
The Sm is projected onto a movable mirror MRw fixed to the end of the ZL stage 82 as shown in FIG. 5, and the reflected beam returns to the laser interferometer 33 and interferes with the reflected beam of the reference beam BSr. The coordinate position of the reflecting surface of the moving mirror MRw,
That is, the coordinate position of the wafer W in the X and Y directions is measured with reference to the reference mirror ML. Now, also in this embodiment, the ZL stage 82 has three Z actuators 32.
XY stage 34 via A and 32B (32C is omitted)
It is mounted on the top and is movable in the Z direction and the tilt direction. However, the ZL stage 82 is coupled to the XY stage 34 via leaf springs 84A and 84B (84C is omitted) at three places around the ZL stage 82, and the rigidity in the horizontal direction (within the XY plane) of the XY stage 34 becomes extremely large. Will be supported.

In this embodiment, a wafer chuck 90 similar to that shown in FIG. 5 is provided on the ZL stage 82. The difference from FIG.
ZL stage 82 with a relatively large stroke (approximately 10 to 15 mm) by driving mechanisms 88A and 88B in the directions.
In the Z direction. Unlike the Z actuators 32A, 32B, and 32C for focus and leveling, the drive mechanisms 88A and 88B need only move the wafer chuck 90 between both ends of the stroke, and use an air cylinder, a link mechanism, or the like. A simple elevation function is sufficient. Further, in the embodiment of FIG. 6, the center up pin 83 shown in FIG. 5 is fixed on the XY stage 34 without moving up and down. When the wafer chuck 90 is at the highest position as shown in FIG. 6, the surface of the wafer W is set to be about 1 to 2 mm from the surface of the optical element at the tip of the projection lens system PL, and the tip of the center-up pin 83 is It is slightly lower (about 2 to 3 mm) than the wafer mounting surface of the chuck 90.

FIG. 6 shows the state of the exposure operation on the wafer W with the above-described configuration. When the exposure operation is completed, the liquid LQ on the wafer chuck 90 is discharged by the operation of discharging the liquid LQ shown in FIG. Is temporarily discharged. Thereafter, when the vacuum chuck of the wafer chuck 90 is released, the drive mechanisms 88A and 88B are operated to operate the wafer chuck 90.
From the position in FIG. As a result, the wafer W is replaced on the front end surfaces of the three center up pins 83, and the upper end surface of the wall portion LB around the wafer chuck 90 is moved to the front end surface of the projection lens system PL (the lower surface of the lens element LE1 in FIG. 3). Pe, parallel plate C in FIG.
(Lower surface of G). When the XY stage 34 is moved to the wafer exchange position in this state, the wafer W is pulled out from just below the projection lens system PL, and moves to the transfer arm 95. At this time, the arm 95 is set at a height that is higher than the upper end surface of the wall portion LB of the wafer chuck 90 and lower than the wafer W on the center-up pin 83.
Go underneath. Then, the arm 90 performs vacuum suction while slightly lifting the wafer W upward, and transports the wafer W to a predetermined unload position. The loading of the wafer W is performed in exactly the reverse of the above sequence.

As shown in FIG. 6, when the laser interferometer 33 projects the reference beam BSr to the reference mirror ML of the projection lens system PL, the reference beam BS
Since the pool of the liquid LQ spreads directly below the optical path of r, it is conceivable that the rise of the saturated vapor of the liquid LQ will cause fluctuations in the optical path of the reference beam BSr. Therefore, in the present embodiment, the cover plate 87 is disposed between the optical path of the reference beam BSr and the liquid LQ, and the vapor flow rising from the liquid LQ is blocked to prevent fluctuation occurring in the optical path of the reference beam BSr.

In order to stabilize the optical path of the reference beam BSr, clean air whose temperature is controlled in a direction intersecting the optical path may be blown into the upper space of the cover plate 87. In this case, the cover plate 87 also has a function of preventing air for air-conditioning air from being directly blown onto the liquid LQ, so that unnecessary evaporation of the liquid LQ can be reduced. Further, in place of the simple cover plate 87, a configuration may be adopted in which the entire optical path of the reference beam BSr is covered with a windshield cylinder.

[0050]

Description of the Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIGS. In this embodiment, the structure of the holder table WH shown in FIG. 1 is combined with the center-up mechanism (pin 83, Z drive unit 85) shown in FIG. Is an improved version of the holder table WH. And FIG.
7B shows a plane of the improved holder table WH, and FIG. 7A shows a cross section taken along the arrow 7A in FIG. 7B. As can be seen from FIGS. 7A and 7B, the holder table WH is held on the XY stage 34 via three Z actuators 32A and 32C (32B is omitted), and is located near the center of the holder table WH. Is provided with three through holes 91. The drive unit 8 is provided in the through hole 91.
The center up pin 83 which moves up and down by 5 passes.

As described above, the projection lens system PL
The height of the bottom end face of the
It is only about 2 mm away from the surface of S (wafer W). Further, the upper end of the wall portion LB provided around the holder table WH is higher than the lowermost end surface of the projection lens system PL.
Therefore, the XY stage 34 is directly used for wafer exchange.
Is moved to pull out the wafer from directly below the projection lens system PL, the width of a part of the auxiliary plate portion HRS needs to be about the diameter of the lens barrel of the projection lens system PL, and the holder into which the liquid LQ is injected. This increases the internal volume of the table WH.

Therefore, in this embodiment, as shown in FIG. 7, a part of the wall portion LB of the holder table WH is cut off, and a liquid-tight door portion DB which can be opened and closed is provided there. The liquid-tight door portion DB is always in the state shown in FIG. 7 while the liquid LQ is being injected.
As shown in FIGS. 7A and 7B, the cutout portion of the wall LB is closed in a liquid-tight state, and when the liquid LQ is discharged from above the holder table WH, as shown by the broken line in FIG. It is designed to open. The liquid-tight door portion DB is set to be slightly lower than the height of the surface of the auxiliary plate portion HRS in the open state. Further, an O-ring OL for ensuring liquid tightness is provided on a wall portion (a cutout portion of the wall portion LB, etc.) of the holder table WH body side in contact with the inner wall of the liquid tight door portion DB as shown in FIG. It is provided at an appropriate position.

In the above configuration, when the wafer on the holder table WH is replaced, the liquid LQ in the holder table WH is first discharged, and then the liquid-tight door portion DB is opened. Thereafter, when the XY stage 34 is moved to the right in FIG. 7, the wafer is pulled out from immediately below the projection lens system PL. At this time, the projection lens system PL is located in the space above the liquid-tight door portion DB that has just opened. Then, raise the center-up pin 83 to move the wafer to the wall LB.
If lifted higher, the wafer can be easily replaced.

According to this embodiment, it is possible to minimize the diameter of the wall portion LB surrounding the holder table WH, and to minimize the total amount of the liquid LQ filled in the holder table WH. Thus, there is an advantage that not only the temperature control of the liquid LQ is facilitated, but also the injection and discharge time of the liquid LQ is minimized. In the structure of the fourth embodiment, it is not necessary to provide a liquid-tight door portion because the wafer chuck descends. However, in the structure of the fourth embodiment, the liquid-tight door portion may be provided. good.

[0055]

FIG. 8 shows a sixth embodiment of the present invention. In this embodiment, a lower container 7 and an upper container 8 are used. The wafer holder 3a for mounting the wafer 3 is formed at the bottom of the inner surface of the lower container 7, the upper surface of the lower container 7 is sealed by the bottom surface of the upper container 8, and the entire volume of the lower container 7 is filled with the immersion liquid 7a. Completely satisfied. On the other hand, the upper container 8 is also filled with the immersion liquid 8a, and the final lens surface 1a of the projection optical system 1 is immersed in the immersion liquid 8a.

A part of the immersion liquid 7a in the lower container 7 is guided to the temperature controller 6 from the discharge port 5 provided on one side surface of the lower container 7, and after being subjected to temperature control in the temperature controller 6, 7 circulates from the inlet 4 provided on the other side to return to the lower container 7. Temperature sensors (not shown) are attached to a plurality of locations in the lower container 7, and the temperature controller 6 makes the temperature of the immersion liquid 7a in the lower container 7 constant based on the output from the temperature sensor. Control. A similar temperature control mechanism is also provided for the immersion liquid 8a in the upper container 8.

In this embodiment, the wafer 3 is moved by moving the lower container 7 and the upper container 8 integrally. On the other hand, since the immersion liquid in the lower container containing the wafer 3 is substantially sealed, it is not only advantageous in terms of temperature stability, but also does not generate pressure distribution due to the flow of eddies and the like in the immersion liquid. . That is, the pressure distribution in the immersion liquid causes the fluctuation of the refractive index and causes the deterioration of the imaging wavefront aberration. However, in the sixth embodiment, the pressure distribution becomes a problem because the immersion liquid filled in the upper container 8 8a only, the optical path L of this part
By forming ₈ sufficiently short, the influence of the immersion liquid flow during wafer movement can be reduced to a level that does not pose a practical problem.

In this embodiment, the lower container 7 and the upper container 8
Are moved together, but it is also possible to move only the lower container 7 and fix the upper container 8. In this configuration, the immersion liquid 8a in the upper container 8 stops completely. Therefore, in the working distance L, it is preferable to form the thickness L ₇ of the immersion liquid 7 a in the lower container 7 sufficiently smaller than the thickness L ₈ of the immersion liquid 8 a in the upper container 8.

[0059]

Description of Other Modifications The embodiments of the present invention have been described above. However, as shown in FIG. 1, the working distance at the time of immersion projection exposure is extremely small, about 1 to 2 mm. Focusing was performed using an off-axis type focus alignment sensor FAD. However, for example, US Pat.
No. 77, U.S. Pat. No. 4,383,757, etc., a beam for focus detection is projected onto the wafer through a peripheral portion in the projection field of view of the projection lens system PL to raise the height of the wafer surface. A focus detection mechanism of a TTL (through-the-lens) method for measuring the position or inclination may be provided.

Further, the focus / alignment sensor FAD shown in FIG.
Although the upper alignment mark is optically detected, this alignment sensor also detects the mark on the wafer W through the reticle R and the projection lens system PL.
T for detecting a mark on the wafer W through only the projection lens system PL in addition to the TTR alignment sensor 45 inside
It may be a TL type alignment sensor. Further, the present invention can be applied in exactly the same manner to any type of exposure apparatus as long as it has a projection optical system that performs projection exposure in the ultraviolet region (wavelength of 400 nm or less).

[0061]

As described above, according to the present invention, there is provided an immersion type exposure apparatus in which a sufficient imaging performance is guaranteed within a range of a feasible temperature control. Also provided is a wafer stage structure suitable for loading and unloading of a wafer in an immersion exposure apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a scanning projection exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view schematically illustrating a scanning exposure sequence.

FIG. 3 is a partial cross-sectional view showing a detailed configuration near a projection lens system in FIG.

FIG. 4 is a block diagram schematically showing a liquid temperature control and liquid supply system according to a second embodiment of the present invention.

FIG. 5 is a partial sectional view showing a structure near a wafer holder and a projection lens system according to a third embodiment of the present invention.

FIG. 6 is a partial sectional view showing a structure near a wafer holder and a projection lens system according to a fourth embodiment of the present invention.

FIGS. 7A and 7B are a cross-sectional view and a plan view illustrating a structure of a holder table according to a fifth embodiment of the present invention.

FIG. 8 is a schematic sectional view showing a main part of a sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Projection optical system 1a ... Final lens surface 7, 8 ... Container 7a, 8a ... Immersion liquid 3 ... Wafer 3a ... Wafer holder 4 ... Injection port 5 ... Discharge port 6 ... Temperature controller L ... Working distance 10 ... Illumination system 12 ... condenser lens system 14 ... mirror 16 ... reticle stage 17 ... laser interferometer system 18 ... motor 19 ... column structure 20 ... reticle stage controller 30 ... base platen 32A, 32B, 3
2C: Actuator 33: Laser interferometer system 34: XY stage 35: Wafer stage controller 36: Drive motor 40: Main controller 50A, 50B: Temperature controller 51: Groove 51 52: Passage 53: Pipe 53A, 53B: Passage 55 ... temperature sensor 60 ... controller 62 ... switching valve 64 ... liquid supply unit 64A ... pump 64B ... temperature controller 66 ... discharge pump 66 80 ... sub-barrel 82 ... ZL stage 83 ... center up pin 84A, 84B ... leaf spring 85 vertical drive mechanism 87 cover plate 88A, 88B drive mechanism 90 wafer chuck 91 through hole 95 arm 112 piping 113 suction surface 114 outer peripheral corner IL pulse illumination light AI illumination area R Reticle Pa: Circuit pattern area SB: Light-shielding band PL: Projection lens system AX ... Optical axis LGa Front lens system LGb Rear lens system Ep Exit pupil LE1 Positive lens element Pe Lower surface CG Parallel plate W Wafer SAa, SAb Shot area SI Projected image WH Holder table LB Wall LQ Liquid HRS Auxiliary plate DB Liquid tight door OL O-ring FAD Focus alignment sensor MRr, MRw Moving mirror ML Reference mirror BSr Reference beam BSm Measurement beam Sf Focus Signal Sa: Alignment signal

Claims (12)

[Claims] A projection optical system for printing and transferring a pattern drawn on a reticle onto a wafer; and a working distance between a lens surface of the projection optical system closest to the wafer and the wafer. An immersion type exposure apparatus in which at least a part is filled with a liquid that transmits exposure light, wherein the length of the working distance is L, the wavelength of the exposure light is λ, and the temperature coefficient of the refractive index of the liquid is N.
A liquid immersion type exposure apparatus characterized in that, when (1 / ° C.), L ≦ λ / (0.3 × | N |). 2. A projection optical system for printing and transferring a pattern drawn on a reticle onto a wafer, wherein a working distance between a lens surface of the projection optical system closest to the wafer and the wafer. In an immersion type exposure apparatus at least partially filled with a liquid that transmits exposure light, an additive that reduces the surface tension of pure water or increases the surface activity of pure water is added to the pure water as the liquid. A liquid immersion type exposure apparatus characterized by using the above. 3. The working distance length L is 2
The immersion type exposure apparatus according to claim 1, wherein the distance is equal to or less than mm. 4. The immersion type exposure apparatus according to claim 1, wherein the reticle and the wafer are arranged so as to be scanned at a constant speed in synchronization with a speed ratio corresponding to a magnification of the projection optical system. 5. An immersion type exposure apparatus according to claim 1, wherein ultraviolet light is used as said exposure light. 6. An optical surface on the wafer side of a tip optical element closest to the wafer in the projection optical system, and a lower end surface of a lens barrel holding the tip optical element is made flush with the optical surface. 6. The immersion type exposure apparatus according to claim 1, wherein the liquid immersion type exposure apparatus is formed so as to have a chamfered outer peripheral surface of a lower end of the lens barrel. 7. An immersion type exposure apparatus according to claim 6, wherein said tip optical element is a parallel flat plate. 8. A wafer is held by a holder table, a wall is erected on an outer periphery of an upper surface of the holder table so that a working distance can be satisfied by the liquid, and the liquid is supplied into the holder table. The immersion type exposure apparatus according to claim 1, wherein a liquid supply unit is provided so as to be recoverable, and a temperature controller is provided on both the holder table and the liquid supply unit. 9. The wafer chuck is held by a wafer chuck, and a wall is erected on an outer periphery of an upper surface of the wafer chuck so that a working distance can be satisfied by the liquid, and at least three wafers penetrate the wafer chuck. The liquid immersion type exposure apparatus according to any one of claims 1 to 7, wherein a pin is provided, and a lifting drive device is attached to the pin so that the wafer can be lifted above the wafer chuck. 10. A wafer is held by a wafer chuck, and a wall is erected on an outer periphery of an upper surface of the wafer chuck so that a working distance can be satisfied by the liquid, and at least three wafers penetrate the wafer chuck. 8. A lift drive device is attached to said wafer chuck so that said pin can be provided and an upper end of said wall portion of said wafer chuck can be made lower than a lower end of said projection optical system. An immersion type exposure apparatus according to any one of the preceding claims. 11. The immersion liquid according to claim 1, wherein a part of said wall is provided with a liquid-tight door part which can be opened and closed to avoid interference with a lower end part of the projection optical system. Type exposure equipment. 12. The projection optical system according to claim 1, wherein a mirror for an interferometer is mounted on a side surface of the projection optical system, and a protection means is provided so as to separate a light beam incident on the mirror and reflected from the vapor from the liquid. The immersion type exposure apparatus according to any one of claims 11 to 11.