JP2006049677A - Variable slit arrangement, illumination device, aligner, and manufacturing method of device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable slit arrangement in which the slit width of illumination light is controlled easily and occurrence of dust due to expansion/contraction of a blade is prevented, along with an illumination device, aligner, or the like using it. <P>SOLUTION: A variable slit arrangement 100 for forming slit-like illumination light EL comprises a first light shielding part 10 which comprises a plurality of blades 20 to define one major side L of the illumination light EL, and a second light shielding part which defines the other major side L of the illumination light EL. The first light shielding part 10 is provided with an expansion/contraction part 24 which expands/contracts the width of at least one blade 20 among a plurality of blades 20 when changing the form of one major side L of the illumination light EL. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus used in a photolithography process for manufacturing a device such as a semiconductor element.

In a photolithography process for manufacturing devices such as semiconductor elements, thin film magnetic heads, and liquid crystal display elements, there is an exposure apparatus that transfers an image of a pattern formed on a photomask or reticle onto a substrate coated with a photosensitive agent such as a photoresist. Commonly used. In this exposure apparatus, the demand for higher integration and miniaturization of resist patterns formed on a substrate becomes stricter each year as the capacity of a semiconductor memory increases and the speed and integration of a CPU processor increase. It has become to. On the other hand, as the pattern is highly integrated and miniaturized, a slight change in exposure conditions increases the defect rate and causes a decrease in yield.
For this reason, in an illuminating device that irradiates the substrate with illumination light through a mask, the integrated exposure amount is uniformized for defects in which the line width of the pattern formed on the substrate is uneven due to uneven illuminance. It prevents by. In particular, in a scanning exposure apparatus that scans a mask and a substrate relative to slit-shaped illumination light and projects and transfers a pattern formed on the mask onto the substrate, for example, Japanese Patent Application Laid-Open No. 10-340854. As disclosed in the publication, there has been proposed a variable slit device that partially changes the slit width of illumination light to make the illuminance of the illumination light uniform.
Japanese Patent Laid-Open No. 10-340854 (FIG. 1)

In the above-described technique, as a light-shielding portion (variable slit portion) that partially changes the slit width of the illumination light, a plurality of blades that are rotatably connected by pin coupling are used, and a push rod is attached to each blade. A plurality of blades are driven to connect.
However, in order to rotate the blade, it is necessary to move the push rod, which is pin-coupled to the blade, in the axial direction and also in the direction orthogonal to the axial direction to follow the rotation of the blade. For this reason, for example, a mechanism for bending the push rod in a direction orthogonal to the axial direction is required, and the apparatus becomes complicated. Further, when the push rod is bent, there is a problem that the position where the push rod is arranged and the position where the shape of the light shielding portion changes (that is, the position where the slit width of the illumination light changes) are shifted.
In addition, in order to solve the above-described problems, there is a technology that enables rotation and relative movement by connecting the connecting portions of each blade by a long hole and a pin, but dust caused by wear at the contact point of the pin and the long hole. Occurs, which adversely affects the illumination lens system and the like.

  The present invention has been made in view of the above-described circumstances, and facilitates control of the slit width of illumination light and can prevent generation of dust due to expansion and contraction of a blade, and illumination using the variable slit device An object is to provide an apparatus, an exposure apparatus, and the like.

The variable slit device and the like according to the present invention employ the following means in order to solve the above-described problems.
1st invention has the some braid | blade (20) for prescribing | regulating one long side (L) of illumination light in the variable slit apparatus (100) for forming slit-shaped illumination light (EL). The first light-shielding part (10) and a second light-shielding part that defines the other long side of the illumination light, and the first light-shielding part includes a plurality of first light-shielding parts when changing the shape of the one long side of the illumination light. An expansion / contraction part (24) for expanding / contracting the width of at least one of the blades is provided.
According to this invention, when at least one of the plurality of blades expands and contracts, the blade can be rotated without changing the arrangement position of the push rod. That is, normally, when each of a plurality of blades is rotatably connected to an adjacent blade at both ends thereof, when a blade rotates, the position of the adjacent blade changes in conjunction with the rotation. Accordingly, it is necessary to bend the push rod. However, since each blade is provided with an expansion / contraction portion that changes the distance between both ends thereof, it is not necessary to bend the push rod.

  The second invention is a variable slit device according to the first invention as a device for adjusting the shape of the illumination light (EL) in the illumination device (121) for irradiating the irradiated object with slit-like illumination light (EL). (121) is used. According to the present invention, it is possible to irradiate the irradiated object with substantially rectangular illumination light in which the slit width is partially changed.

  In the third aspect of the invention, the mask (R) and the substrate (W) are irradiated in the longitudinal direction of the illumination light (EL) while irradiating the substrate (W) with the slit-shaped illumination light (EL) through the mask (R). In the exposure apparatus (EX) for sequentially exposing the pattern formed on the mask (R) to the substrate (W) by relative scanning in a direction substantially orthogonal to the mask (R), the mask (R) has a substantially rectangular illumination light (EL). The illumination device (121) according to the second aspect of the present invention is used as the illumination device (121) that emits light. According to the present invention, since the illumination light in which the uneven illuminance is corrected is used, the uneven exposure due to the uneven illuminance can be prevented.

  According to a fourth aspect of the present invention, in the device manufacturing method including the lithography step, the exposure apparatus (EX) according to the third aspect is used in the lithography step. According to the present invention, a device having a fine pattern can be efficiently manufactured.

According to the present invention, the following effects can be obtained.
Since the blade rotates while expanding and contracting, the arrangement position of the push rod pin-coupled to the blade does not change, and the relationship between the shape change of the light shielding portion and the position of the push rod can be easily grasped.
In addition, when uneven illuminance occurs in the slit-shaped illumination light, the shape of the light shielding portion can be appropriately changed in accordance with the illuminance, so that uneven illuminance can be corrected. Thereby, uneven exposure due to uneven illumination can be prevented, the line width formed on the substrate can be made uniform, and the occurrence of defective line width can be reduced. In particular, when a fine pattern is formed, it is effective and the yield can be improved.
A device having a fine pattern can be efficiently manufactured, and the capacity of a semiconductor memory can be increased and the speed and integration of a CPU processor can be increased.

Hereinafter, embodiments of the variable slit device of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a variable slit device 100.
The variable slit device 100 forms the illumination light EL shaped into a rectangle through a shaping optical system (not shown) into a slit-shaped illumination light EL having a desired shape, and the slit-shaped illumination light EL In order to define one long side L, a light shielding part (first light shielding part) 10 that shields a part of the passing illumination light EL and an actuator part 50 that drives the light shielding part 10 are provided. Further, the variable slit device 100 includes a light shielding plate (second light shielding unit) (not shown) that shields a part of the passing illumination light EL in order to define the other long side L of the slit-shaped illumination light EL. . In other words, the variable slit device 100 drives the actuator unit 50 to partially change the slit width of the passing illumination light EL.
Incidentally, the slit width S direction of the illumination light EL and Y ₀ direction, the direction parallel to the longitudinal direction of the illumination light EL and X ₀ direction.

FIG. 2 is a diagram illustrating the light shielding unit 10. 2B and 2C are views showing the plates 20a and 20b constituting the blade 20. FIG.
The light-shielding unit 10 is configured by a plurality of blades 20 that are rotatably connected to each other. At both ends of each blade 20, a connecting portion 22 connected to the adjacent blade 20 is provided. The connecting portion (rotation support portion) 22 supports the blades 20 in a rotatable manner by fitting the pin-like members 23 into through holes formed at both ends of the blade 20. In addition, the pin-shaped member 23 is formed so that the end portion projects in a bowl shape in order to prevent leakage of illumination light from the fitting portion.
In addition, the blades 20 are alternately stacked in two stages on the upper and lower sides in the optical axis method. Furthermore, the tip portion of each blade 20 on the illumination light EL side is formed to a thickness of about 10 μm. This is to make the positions in the optical axis direction where the slit-shaped illumination light EL is blocked as equal as possible.
Each connecting portion 22 is connected to a rod (rod portion) 73 of an actuator portion 50 described later (see FIG. 3). By each of the rod 73 is moved by an arbitrary distance Y ₀ direction, the connecting portion 22 is moved in the Y ₀ direction, by rotating blade 20, is changed shape of the tip portion of the light blocking portion 10 (FIG. 2 (a)). In this way, the slit width S of the illumination light EL is partially changed.
The reason why the blade 20 is formed in an inverted trapezoidal shape with respect to the illumination light EL is to avoid interference with other blades 20 when the blade 20 rotates. Further, the has a shape that extends in Y ₀ direction is to ensure blocking the illumination light EL.

The blade 20 is composed of two plates (plate members) 20a and 20b. FIG. 2B shows the plate 20a, and FIG. 2C shows the plate 20b.
The plates 20a and 20b are made of a heat-resistant material such as stainless steel in order to shield the illumination light EL.
Further, the blade 20, stretching the width of the blade 20 itself, i.e., stretchable portion 24 expanding and contracting in the X ₀ direction is provided. The expansion / contraction part 24 is comprised from the convex edge part 25a and the concave edge part 26a which were formed in the side surface of the board 20a, and the convex edge part 25b and the concave edge part 26b which were formed in the side surface of the board 20b.
As shown in FIGS. 2B and 2C, the convex edge portions 25a, b and the concave edge portions 26a, b are inseparably formed on the side surfaces of the plates 20a, 20b. Further, three combinations of the convex edge portion 25a and the concave edge portion 26a are formed on the side surface of the plate 20a, respectively, and the convex edge portion 25b and the concave edge portion 26b are formed on the side surface of the plate 20b. Three combinations are formed. And the combination of the convex edge part 25a and the concave edge part 26a which were formed in the board 20a, and the combination of the convex edge part 25b and the concave edge part 26b which were formed in the board 20b are arrange | positioned so that it may become staggered. The
Further, the convex edge portion 25b and the concave edge portion 26b formed on the side surface of the plate 20b are slidably fitted to the convex edge portion 25a and the concave edge portion 26a formed on the side surface of the plate 20a. . As a result, the plate 20a and the plate 20b can move relative to each other, and the width of the blade 20 itself is expanded and contracted.
Each tongue 25a, b and the respective concave edge portions 26a, b is, because it is formed along a plane substantially perpendicular to the optical axis of the illumination light EL _{(Z 0} direction), and the plate 20a Even if it moves relative to the plate 20b, the illumination light EL can be blocked. In addition, surface treatment is performed on the surfaces (contact surfaces) of the convex edge portion 25 and the concave edge portion 26 so that the contact resistance is reduced.

Further, the blade 20 is provided with a guide portion 28 for relatively moving the plate 20a and the plate 20b only in the linear direction connecting the connecting portions 22 at both ends.
The guide portion 28 is configured by the side surfaces 29a and 29b of the respective convex edge portions 25a and 25b constituting the expandable portion 24. As described above, the three convex edge portions 25a and 25b are formed on the plate 20a and the plate 20b, respectively. Further, the convex edge portion 25a formed on the plate 20a and the convex edge portion 25b formed on the plate 20b are arranged at alternate positions. The side surface 29 a of the convex edge portion 25 a and the side surface 29 b of the convex edge portion 25 b are formed in parallel to the linear direction connecting the connecting portions 22.
Therefore, when the plate 20a and the plate 20b are fitted, the side surface 29a of the convex edge portion 25a and the side surface 29b of the convex edge portion 25b slide while being in contact with each other. Thus, the plates 20a and 20b are relatively moved only in the linear direction connecting the connecting portions 22. Further, since the side surfaces 29a, b are provided at a plurality of locations, the relative movement of the plates 20a, 20b in a direction other than the linear direction connecting the connecting portions 22 is restricted.
With the above structure, the two plates 20a and 20b smoothly move relative to each other, so that the blade 20 itself can expand and contract in a linear direction connecting the connecting portions 22 at both ends.

Incidentally, the reason for providing the collapsible portion 24 to each blade 20 is to avoid micromotion of the X ₀ direction of the connecting portion 22 due to the rotational movement of the blade 20. That is, if the blade 20 is not provided with the expansion / contraction part 24, when one of the connecting parts 22 is moved in the _Y0 direction, the blade 20 rotates around the other connecting part 22 and the connecting part 22 moves in the _X0 direction. Will also move slightly.
Therefore, as in the present embodiment, the case of providing the elastic portion 24 to the blade 20, also rotates and the blade 20, since the blade 20 itself expands and contracts, there is no movement in the X ₀ direction of the connection portion 22 . As shown in FIG. 2A, even if one connecting portion 22 of the blade 20 moves in the _Y0 direction, the expansion / contraction portion 24 functions and the blade 20 itself expands / contracts. The interval YL in the ₀ direction is always kept constant. Thereby, the structure of the variable slit device 100 and the shape control of the light shielding unit 10 can be simplified.

3A and 3B are diagrams showing the actuator unit 50, in which FIG. 3A is a front view, FIG. 3B is a side view, and FIG. 3C is a cross-sectional view of FIG.
The actuator unit 50 is connected to each connecting unit 22 and moves each blade 20 in the X direction. The actuator unit 50 is composed of the same number of linear actuators (actuators) 70 as the coupling unit 22, and the linear actuator 70 is a rod connected to a motor 71, a micrometer head unit 72 of a screw / nut mechanism, and the coupling unit 22. 73, a base 74, and the like.
Base 74 is a plate-like member, the convex portion 74a formed on its upper surface is arranged parallel to the Y ₀ direction. The rod portion 72 a of the micrometer head portion 72 is fixed to the rear end of the base 74 via the angle 76. On the other hand, the head portion 72 b of the micrometer head portion 72 is connected to the motor 71 via the coupling 75. The motor 71 via a motor flange 77, is the placing to be movable in the Y ₀ direction on the base 74. The motor flange 77 has a recess formed on the bottom surface thereof, and can move along the protrusion 74 a of the base 74. A rod 73 is connected to the motor flange 77.
With this configuration, when the motor 71 is rotated, the micrometer head unit 72 converts the rotational motion into a linear motion and expands and contracts, so that the motor 71 moves in the _Y0 direction together with the motor flange 77. The movement of the motor flange 77 through the rod 73 is transmitted to the connecting portion 22 of the blade 20, they move the blade 20 in the _{Y 0} direction.
Further, the motor 71, compared to the blade 20, since X ₀ direction width is large, the upper and lower stages in the linear actuator 70 is an optical axis direction (Z ₀ direction), also a staggered position in Y ₀ direction Be placed.
Then, the movement amount of the Y ₀ direction of the coupling portion 22 is determined from the amount of movement of the micrometer head 72, the information is sent to the main control system 220 for controlling the variable slit apparatus 100. In addition, an encoder may be provided in the motor 71 to measure the rotation amount of the motor 71.

Next, an embodiment in which the variable slit device 100 described above is applied to an illumination device and an exposure device will be described. FIG. 4 is a schematic diagram showing the exposure illumination system 121 and the exposure apparatus EX.
The exposure apparatus EX moves the reticle (mask) R and the wafer (substrate) P relatively synchronously in the one-dimensional direction while irradiating the reticle R with exposure illumination light (exposure light) EL. This is a so-called scanning stepper, which is a step-and-scan type scanning exposure apparatus that transfers a formed pattern (circuit pattern or the like) onto the wafer W via the projection optical system PL. In such an exposure apparatus EX, the pattern of the reticle R can be exposed in an area on the wafer W wider than the exposure field of the projection optical system PL.

The exposure apparatus EX includes a light source 120, an exposure illumination system 121 that irradiates a reticle R with exposure illumination light EL from the light source 120, a reticle stage RS that holds the reticle R, and an exposure illumination light EL that is emitted from the reticle R. A projection optical system PL for irradiating W, a wafer stage WS for holding the wafer W, a main control system 220 for comprehensively controlling the operation of the exposure apparatus EX, and the like. The exposure apparatus EX is housed in a chamber (not shown) as a whole.
In the XYZ orthogonal coordinate system, the X axis and the Y axis are set so as to be parallel to the wafer stage WS holding the wafer W, and the Z axis is set in a direction orthogonal to the wafer stage WS. Actually, in the XYZ orthogonal coordinate system in the figure, the XY plane is set to a plane parallel to the horizontal plane, and the Z axis is set to the vertical direction.

As the light source 120, vacuum ultraviolet rays having a wavelength of about 120 nm to about 190 nm, for example, ArF excimer laser (wavelength: 193 nm), fluorine (F ₂ ) laser (157 nm), krypton (Kr ₂ ) laser (146 nm), argon (Ar ₂ ) ) One that generates a laser (126 nm) or the like is used. The reason why vacuum ultraviolet rays are used as the illumination light EL for exposure is to cope with the fine line width of the pattern formed on the wafer W.
In addition, the light source 120 is provided with a light source control device (not shown). This light source control device responds to an instruction from the main control system 220 and emits the oscillation center wavelength and the spectrum half of the exposure illumination light EL to be emitted. Performs control of value width, trigger control of pulse oscillation, etc.

The exposure illumination system (illumination device) 121 irradiates the exposure illumination light EL emitted from the light source 120 in a predetermined illumination area on the reticle R with a substantially uniform illuminance distribution.
Specifically, the exposure illumination light EL emitted from the light source 120 is deflected by the deflecting mirror 130 and enters a variable dimmer 131 as an optical attenuator. The variable dimmer 131 can adjust the dimming rate stepwise or continuously in order to control the exposure amount of the photoresist on the wafer. The exposure illumination light EL emitted from the variable dimmer 131 is deflected by the optical path deflecting mirror 132, and then sequentially passes through the first fly-eye lens 133, the zoom lens 134, the vibration mirror 135, and the like. The lens 136 is reached.
On the exit side of the second fly-eye lens 136, a switching revolver 137 for an illumination optical system aperture stop for setting the size and shape of the effective light source as desired is disposed. In the present embodiment, in order to reduce the light amount loss at the illumination optical system aperture stop, the size of the light flux to the second fly's eye lens 136 by the zoom lens 134 is variable.
The revolver 137 includes, for example, an aperture stop (normal aperture) made of a normal circular aperture, an aperture stop (small σ stop) for reducing a σ value that is a coherence factor made of a small circular aperture, a ring, and the like. A zone-shaped aperture stop (band zone stop) for band illumination and a modified aperture stop formed by arranging a plurality of apertures eccentrically for the modified light source direction are provided. The revolver 137 is rotated by a driving device such as a motor, and one of the aperture stops is selectively disposed on the optical path of the exposure illumination light EL, so that the shape and size of the secondary light source on the pupil plane can be reduced. It is limited to ring zones, small circles, large circles, or the fourth. As described above, the illumination condition of the reticle R can be changed by arranging any of the stops on the optical path of the exposure illumination light EL.
Further, the exposure illumination light EL emitted from the aperture of the illumination optical system aperture stop illuminates the illumination field stop (reticle blind) 141 via the condenser lens group 140. The illumination field stop 141 is disclosed in JP-A-4-196513 and US Pat. No. 5,473,410 corresponding thereto.
The exposure illumination light EL emitted from the illumination field stop 141 passes through an illumination field stop imaging optical system (reticle blind imaging system) including deflection mirrors 142 and 145 and lens groups 143, 144, 146 and 147. To the reticle R.
As shown in FIG. 4, the variable slit device 100 is disposed at a position conjugate with the pattern of the reticle R (strictly, in the vicinity of the conjugate position), and changes the slit width S of the illumination light EL for exposure. Let Further, when the slit width S of the variable slit device 100 is changed, the slit width S in the scanning direction (Y direction) of the exposure illumination light EL irradiated on the reticle R is changed.
As a result, an illumination area (exposure field) having the same shape as the opening of the variable slit device 100 is formed on the reticle R.

The reticle stage RS is provided immediately below the exposure illumination system 121 and includes a reticle holder or the like that holds the reticle R. The reticle holder (not shown) is supported by the reticle stage RS, has an opening corresponding to the pattern on the reticle R, and holds the reticle R pattern by vacuum suction with the pattern on the reticle R down. The reticle stage RS is one-dimensionally scanned and moved in the Y direction by a drive unit (not shown), and can be finely moved in the X direction and the rotation direction (θ direction around the Z axis). For example, a linear coil motor is used as the drive unit. Accordingly, the reticle R can be positioned so that the center of the pattern area of the reticle R passes through the optical axis of the projection optical system PL.
Then, the position of reticle R in the Y direction is sequentially detected by laser interferometer 150 and output to main control system 220.

The projection optical system PL is formed by sealing a plurality of projection lens systems such as a lens made of fluoride crystals such as fluorine-doped quartz, fluorite, and lithium fluoride and a reflecting mirror with a projection system housing (lens barrel 169), It is provided directly below reticle stage RS. The projection lens system reduces the illumination light EL emitted through the reticle R by a predetermined projection magnification β (β is, for example, ¼), and converts the pattern image of the reticle R into a specific area (shot) on the wafer W. (Image). Each element of the projection lens system of the projection optical system PL is supported by the projection system housing via a holding member (not shown), and each holding member is, for example, in an annular shape so as to hold the peripheral edge of each element. Is formed.
Since vacuum ultraviolet rays such as an F ₂ laser are used as the illumination light EL for exposure, fluorite (CaF ₂ crystal), quartz doped with fluorine, hydrogen, etc., as an optical glass material (optical element) with good transmittance Glass, magnesium fluoride (MgF ₂ ), or the like is used. In this case, in the projection optical system PL, it is difficult to obtain a desired imaging characteristic (chromatic aberration characteristic, etc.) by using only a refractive optical member. Therefore, the catadioptric system in which the refractive optical member and the reflecting mirror are combined. May be adopted.

The wafer stage WS includes a wafer holder 180 or the like that holds the wafer W. Wafer holder 180 is supported by wafer stage WS and holds wafer W by vacuum suction. The wafer stage WS is formed by superposing a pair of blocks movable in directions orthogonal to each other on the surface plate 183, and can be moved in an XY plane by a drive unit (not shown).
Then, the position of the wafer stage WS in the X direction and the Y direction is sequentially detected by a laser interferometer 151 provided outside, and is output to the main control system 220 (not shown).
At the end of the wafer stage WS on the -Y side, a Y moving mirror 152Y made of a plane mirror is extended in the X direction. A measurement beam from a Y-axis laser interferometer 151Y disposed substantially perpendicularly to the Y movable mirror 152Y is projected, and the reflected light is received by the Y-axis laser interferometer 151Y, whereby the Y position of the wafer W is received. Is detected. Further, the X position of the wafer W is detected by an X-axis laser interferometer 151X (not shown) with a substantially similar configuration.
Then, by moving the wafer stage WS in the XY plane, an arbitrary shot area on the wafer W is positioned at the projection position (exposure position) of the pattern on the reticle R, and an image of the pattern on the reticle R is projected and transferred onto the wafer W. To do.
A grazing incidence autofocus sensor 181 and an off-axis alignment sensor 182 for detecting the position (focus position) and tilt angle of the surface of the wafer W are provided above the wafer stage WS. .

The main control system 220 (not shown) repeatedly performs an exposure operation of controlling the positions of the reticle stage RS and the wafer stage WS and transferring the pattern image formed on the reticle R to a shot area on the wafer W. .
Further, the actuator unit 50 of the variable slit device 100 is instructed to control the shape of the light shielding unit 10 to make the integrated exposure amount uniform.

By the way, the exposure illumination light EL, that is, the ArF excimer laser light has a property that it is easily absorbed by oxygen molecules, organic substances, etc. (hereinafter referred to as light-absorbing substances), and therefore exists in the space through which the exposure illumination light EL passes. It is necessary to reduce the light-absorbing material and allow the exposure illumination light EL to reach the upper surface of the wafer W with sufficient illuminance.
For this reason, the space through which the illumination light EL for exposure passes, that is, the illumination optical path (the optical path from the light source 120 to the reticle R) and the projection optical path (the optical path from the reticle R to the wafer W) are blocked from the external atmosphere. Is filled with a low light-absorbing gas (for example, an inert gas such as nitrogen, helium, argon, neon, krypton, or a mixed gas thereof) having a low absorption property for light in the vacuum ultraviolet region.

Specifically, a casing 160 is provided in the optical path from the light source 120 to the variable dimmer 131, a casing 161 is provided in the optical path from the variable dimmer 131 to the illumination field stop 141, and the lens group 143 to the lens group 147. The illumination field stop imaging optical system is provided with a casing 162 that is shielded from the external atmosphere and filled with a low-absorbency gas in the optical path. The casing 161 and the casing 162 are connected by a casing 163.
In the projection optical system PL, the lens barrel 169 serves as a casing, and the light path is filled with a low-absorbency gas.

Further, the casings 161, 162 and the lens barrel 169 are provided with air supply valves 200, 201, 206 and exhaust valves 210, 211, 216, respectively, and these air supply valves 200, 201, 206 and exhaust valves 210, 211 and 216 are connected to a gas supply / exhaust ring system (not shown) so that a low-absorbance gas is supplied into each space and a light-absorbing substance is discharged to the outside.
In this way, the space through which the exposure illumination light EL passes is blocked from the external atmosphere and filled with the low-absorbency gas.

Subsequently, a method for performing an exposure process for transferring a pattern formed on the reticle R onto the wafer W using the variable slit device 100, the exposure illumination system 121, and the exposure apparatus EX having the above-described configuration will be described. To do.
Reticle R and wafer W are placed on reticle stage RS and wafer stage WS, respectively, and reticle R is irradiated with exposure illumination light EL from exposure illumination system 121. The light from the illumination area on the reticle R is guided onto the wafer W via the projection optical system PL, and the pattern in the illumination area of the reticle R is projected on the wafer W after being reduced.
Then, the reticle R and the wafer W are moved synchronously with each other in the direction of the slit width S of the exposure illumination light EL while being irradiated with the slit-shaped exposure illumination light EL on the reticle R, and formed on the reticle R. The exposed pattern is transferred and exposed onto the wafer W via the projection optical system PL. By repeatedly performing such an exposure operation, the pattern formed on the reticle R is sequentially exposed to each shot area on the wafer W.
At this time, if there is uneven illumination in the exposure illumination light EL irradiated to the reticle R, the integrated exposure amount becomes non-uniform, and the line width of the pattern formed on the wafer W becomes non-uniform. Since the non-uniform line width causes a failure such as a disconnection, it is necessary to make the integrated exposure amount by the illumination light EL for exposure uniform.

Here, the principle of correcting uneven exposure due to uneven illumination will be described. FIG. 5 is a diagram for explaining uneven illuminance of exposure illumination light, etc. FIGS. 5A to 5D show forms of uneven illuminance (distribution), and FIGS. FIG. 4 is a diagram showing the shape of the opening of the variable slit device 100 for correcting these uneven illuminances, that is, the shape of the light shielding unit 10.
The illumination light EL for exposure is usually formed in a slit shape, and irradiates the wafer W via the reticle R. Then, by scanning the reticle R and the wafer W in the direction of the slit width S of the exposure illumination light EL, the pattern of the reticle R is transferred to a rectangular shot area formed on the wafer W. At this time, if the illuminance of the exposure illumination light EL is uniform and the scanning speed is constant, the integrated exposure amount is uniform, and the shot area on the wafer W should be uniformly exposed.
However, in practice, the illuminance of the exposure illumination light EL is often uneven. For example, as shown in FIG. 5A, the illuminance of the exposure illumination light EL is higher on the left side than the appropriate value, (+ X ₀ side) becomes such a state occurs low. When exposure processing is performed with such non-uniform exposure illumination light EL, the left side of the shot area is so-called overexposed and the right side is underexposed. As a result, the exposure of the photosensitive agent (photoresist) becomes non-uniform, and the line width formed on the wafer W becomes non-uniform.
Therefore, it becomes necessary to correct the uneven illuminance of the illumination light EL for exposure as described above. As a correction method, in a place where the illuminance is higher than an appropriate value (overexposure), the area irradiated with the exposure illumination light EL is reduced in order to reduce the exposure amount. That is, the slit width S is narrowed. Conversely, at a place where the illuminance is lower than the appropriate value (underexposure), the area irradiated with the exposure illumination light EL is increased in order to increase the exposure amount. That is, the slit width S is increased. That is, the variable slit device 100 adjusts the slit width S by the variable slit device 100 so that the integrated exposure amount is adjusted to be substantially uniform.
In the example described above, as shown in FIG. 5E, the light blocking portion 10 of the variable slit device 100 is driven so as to narrow the left slit width S and widen the right slit width S. Thereby, the exposure amount decreases on the left side, while the exposure amount increases on the right side, so that the exposure unevenness due to the uneven illumination intensity of the exposure illumination light EL can be corrected.

As for the illuminance unevenness of the exposure illumination light EL, as in the example described above, the illuminance changes at a constant ratio from the right to the left (primary unevenness or uneven inclination), and the illuminance changes to a radiation form. Second-order unevenness (FIG. 5B), quaternary curve-shaped fourth-order unevenness (FIG. 5C), or random unevenness in which unevenness in illuminance occurs randomly (FIG. 5D). Exists.
In the case of primary unevenness, as described above, the amount of exposure can be adjusted substantially uniformly by changing the slit width S at a constant ratio (FIG. 5E). Further, in the case of secondary unevenness, quadratic unevenness, or random unevenness, exposure is performed by changing the slit width S as shown in FIGS. 5F to 5H in accordance with the illuminance distribution. By correcting the amount substantially uniformly, it is possible to suppress the occurrence of uneven exposure due to uneven illumination.

  The exposure amount may be measured by arranging an illuminometer in the optical path of the exposure illumination light EL. Alternatively, the exposure amount may be indirectly measured by measuring the line width on the exposed wafer W. Further, the timing (frequency) of measuring the exposure amount may be any shot area, wafer W, or lot.

  The variable slit device 100 is not limited to correcting exposure unevenness due to uneven illumination. For example, when the photoresist film thickness is uneven, the slit width S of the variable slit device 100 can be changed in accordance with the uneven film thickness. That is, in a region where the photoresist film is thick, the slit width S is widened to increase the exposure amount. On the other hand, in a thin region, the slit width S is narrowed to reduce the exposure amount. It is also possible to expose substantially uniformly. As described above, the uneven exposure due to the uneven film thickness of the photoresist can also be corrected.

Next, the operation of the variable slit device 100 when correcting uneven exposure due to uneven illumination will be described.
First, as described above, the exposure amount of the illumination light EL for exposure reaching the wafer W is indirectly measured by an illuminometer arranged in the optical path or by measuring the line width on the already exposed wafer W. Is measured. And based on the measurement result, the actuator part 50 of the variable slit apparatus 100 is controlled for every shot area, every wafer W, or every lot, and the shape of the light-shielding part 10 is changed. As described above, the shape of the light shielding unit 10 is determined according to the form of uneven exposure.
The linear actuator 70 of the actuator unit 50 is driven, moving in a direction (Y ₀ direction) toward each rod 73 to the exposure illumination light EL, connecting portion 22 of each blade 20 of the light shielding portion 10, the rod 73 depending on the amount of movement, moves in the Y ₀ direction. In this case, the function expansion portion 24 of the blade 20, so to stretch the distance between the connecting portion 22, X ₀ direction distance between the connecting portion 22 is unchanged. For this reason, it is possible to easily control the shape of the front end portion of the light shielding portion 10, that is, the portion that shields the exposure illumination light EL.
As described above, by changing the shape of the light-shielding portion 10 in the variable slit device 100, it is possible to correct exposure unevenness due to uneven illumination and form a pattern with a uniform line width on the wafer W. .

  Note that the operation procedures shown in the above-described embodiment, or the shapes and combinations of the components are examples, and can be variously changed based on process conditions, design requirements, and the like without departing from the gist of the present invention. is there. For example, the present invention includes the following modifications.

  In this embodiment, in order to define the other long side L of the slit-shaped illumination light EL, a part of the illumination light EL that passes is shielded by a light shielding plate (not shown). You may comprise similarly to the light-shielding part 10. FIG. In this case, similarly to the present embodiment, the actuator unit 50 may be provided, and the shape of the other long side L of the illumination light EL may be changed to an arbitrary shape.

  As a linear actuator, a rack and pinion mechanism using a linear motor or a servo motor, a cam mechanism, or the like can be used in addition to a voice coil motor.

  The use of the exposure apparatus is not limited to the exposure apparatus for manufacturing a semiconductor device. For example, an exposure apparatus for liquid crystal that exposes a liquid crystal display element pattern on a square glass plate or a thin film magnetic head Widely applicable to exposure apparatus.

  The light source of the exposure apparatus to which the present invention is applied includes not only KrF excimer laser (248 nm), ArF excimer laser (193 nm), F2 laser (157 nm), but also g-line (436 nm) and i-line (365 nm). Can be used. Further, the magnification of the projection optical system may be not only a reduction system but also an equal magnification or an enlargement system.

  The reaction force generated by the movement of the reticle stage may be mechanically released to the floor (ground) using a frame member as described in JP-A-8-330224.

  An exposure apparatus to which the present invention is applied assembles various subsystems including the constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  In addition, in the semiconductor device, the process of designing the function and performance of the device, the process of manufacturing a mask (reticle) based on this design step, the process of manufacturing a wafer from a silicon material, and the exposure apparatus of the above-described embodiment It is manufactured through a wafer processing process for exposing a pattern to a wafer, a device assembly process (including a dicing process, a bonding process, and a packaging process), an inspection process, and the like.

Diagram showing variable slit device The figure which shows the shading part Diagram showing actuator Schematic diagram showing exposure illumination system and exposure apparatus The figure explaining the illumination intensity nonuniformity of the illumination light for exposure

Explanation of symbols

10 Shading part (first shading part)
20 blade 20a, 20b plate (plate member)
22 Connecting part (Rotating support part)
24 Telescopic part 28 Guide part 73 Rod (rod part)
100 Variable slit device 121 Exposure illumination system (illumination device)
L Long side EL Illumination light, Exposure illumination light EX Exposure equipment R Reticle (mask)
W Wafer (Substrate)

Claims (6)

In a variable slit device for forming slit-shaped illumination light,
A first light shield having a plurality of blades for defining one long side of the illumination light;
A second light shielding part that defines the other long side of the illumination light,
The variable light slit, wherein the first light-shielding portion includes an expansion / contraction portion that expands / contracts a width of at least one of the plurality of blades when the shape of the long side of the illumination light is changed. apparatus. The at least one blade is configured by stacking two or more plate members,
The variable slit device according to claim 1, wherein the stretchable part moves the two or more plate members relative to each other. A rod portion rotatably supporting each of both end portions of the at least one blade;
The variable slit device according to claim 2, further comprising a guide portion that guides the two or more plate members in a linear direction connecting the rotation support portions supported by the rod portions. In the illumination device that irradiates the irradiated object with slit-shaped illumination light,
The variable slit apparatus as described in any one of Claims 1-3 is used as an apparatus which adjusts the shape of the said illumination light, The illuminating device characterized by the above-mentioned. While irradiating the substrate with slit-shaped illumination light through a mask, the mask and the substrate are relatively scanned in a direction substantially perpendicular to the longitudinal direction of the illumination light, thereby forming the pattern formed on the mask. In an exposure apparatus that sequentially exposes a substrate,
An exposure apparatus using the illumination apparatus according to claim 4 as an illumination apparatus that irradiates the mask with substantially rectangular illumination light. A device manufacturing method including a lithography process, wherein the exposure apparatus according to claim 5 is used in the lithography process.

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