JP4581639B2 - Variable slit apparatus, illumination apparatus, exposure apparatus, and device manufacturing method - Google Patents

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 the exposure apparatus, a defect in the line width of a pattern that becomes non-uniform due to uneven illuminance is prevented by making the integrated exposure amount uniform. 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 Japanese Laid-Open Patent Publication No. 2000-82655 and Japanese Laid-Open Patent Publication No. 2000-82655, there has been proposed a variable slit apparatus in which the slit width of illumination light is partially changed to make the integrated exposure amount uniform.
Japanese Patent Laid-Open No. 10-340854 (FIG. 1) JP 2000-82655 A (FIG. 1)

  In the technique described above, a plurality of blades are arranged in the longitudinal direction of the slit-shaped illumination light, an actuator is connected to each blade, and the slit width of the illumination light is partially changed by driving. In order to eliminate uneven exposure due to uneven illumination with high accuracy, it is desirable to use a large number of blades. That is, it is desirable to finely control the slit width of the illumination light by increasing the locations (positions in the longitudinal direction) where the slit width can be changed. For this reason, it is necessary to increase the number of actuators in accordance with the number of blades and to close the arrangement interval of the actuators.

  However, when the number of actuators is increased, there is a problem that the apparatus becomes complicated and large. In addition, the increase in actuator is accompanied by heat generation, which has a problem of adversely affecting an optical system such as an exposure apparatus.

  The present invention has been made in view of the above circumstances, and provides a variable slit device capable of finely controlling the slit width of slit-shaped illumination light, and an illumination device, an exposure device, and the like using the variable slit device. Objective.

The variable slit device and the like according to the present invention employ the following means in order to solve the above-described problems.
A first aspect of the present invention is a variable slit device (100) for forming slit-shaped illumination light (EL), wherein the first end portion defines one long side (L1) in the longitudinal direction of illumination light (EL). A plurality of first blades (30a) having (80a) and a plurality of second blades (30b) having a second end (80c) defining the other long side (L2) in the longitudinal direction of the illumination light. The first blade and the second blade are arranged so that the first end and the second end are displaced from each other in a predetermined position with respect to the longitudinal direction of the illumination light. According to the present invention, the first end and the second end are displaced from each other at a predetermined position, so that the first end and the second end are twice as large as the positions of the first end and the second end coincide with each other. It becomes equivalent to the presence of control points, and the slit shape of the illumination light can be finely controlled.

  One long side (L1) is defined by driving the first blade (30a) at a first driving position that moves the first blade (30a) in a direction perpendicular to the longitudinal direction of the illumination light (EL), and the other long side (L1). The side (L2) is defined by driving a plurality of second blades (80c) in a second driving position that moves the second blade (80c) in a direction orthogonal to the longitudinal direction of the illumination light. By defining either one or both, the slit shape of the illumination light can be finely controlled.

  The plurality of first blades (30a) and the plurality of second blades (30b) have substantially the same size, and the first driving position and the second driving position are illumination light (EL). Can be realized easily by simply translating the plurality of first blades and the plurality of second blades by a predetermined amount, respectively.

  Further, the first drive position and the second drive position are arranged by shifting the first blade (30a) and the second blade (30b) by approximately half the length in the longitudinal direction of the illumination light (EL). The same effect as using a half-length blade can be obtained, and the equipment cost can be reduced.

  The plurality of first blades (30a) and / or the plurality of second blades (30b) have both end portions (80b, 80d) extending in a direction intersecting with the longitudinal direction of the illumination light (EL). If the first blade and / or the plurality of second blades are rotatably connected at both end portions, the plurality of first blades and the plurality of second blades can be arranged without gaps, and illumination light leaks. Can be prevented.

The driving mechanism (50, 60) further drives the plurality of first blades (30a) and / or the plurality of second blades (30b), and the first driving position and / or the second driving position is driven. With respect to the position of the drive shaft (72, 72a, 72b) of the mechanism, the position of the plurality of first blades and the plurality of second blades can be changed by this drive mechanism.

Further, the plurality of first blades (30a) and / or the plurality of second blades (30b) are rotatably connected at both side end portions (80b, 80d) extending in a direction intersecting the longitudinal direction of the illumination light (EL). The drive shafts (72, 72a, 72b) of the drive mechanism (50, 60) are arranged at positions where the side end portions (80b, 80d) are rotatably connected. The positions of the first blade and the plurality of second blades can be changed smoothly.

  The drive mechanism (50, 60) is configured to move the plurality of first blades (30a) and / or the plurality of second blades (30b) in the optical path direction of the illumination light (EL). Alternatively, the slit shape of the illumination light can be finely controlled by moving the second blade.

Further, the plurality of first blades (30a) and / or the plurality of second blades (30b) are rotatably connected at both side end portions (80b, 80d) extending in a direction intersecting the longitudinal direction of the illumination light (EL). The drive shaft of the drive mechanism (50, 60) is arranged at a position different from both side end portions of the first blade and / or the second blade . According to the present invention, the positions of the plurality of blades can be changed smoothly.

Further, the drive shaft of the drive mechanism (50, 60) is arranged at the central part of the plurality of first blades (30a) and / or the central part of the second blade (30b) . It becomes possible to control the position.

The drive mechanism (50, 60) illuminates the first drive member (50) that moves the plurality of first blades (30a) in the optical path direction of the illumination light (EL) and the plurality of second blades (30b). With the second drive member (60) that moves in the optical path direction of the light, the blur width of the peripheral edge of the illumination light can be set optimally.

In the variable slit device (100) for forming slit-shaped illumination light, the first end (380a) defining the long side (L1) in the longitudinal direction of the illumination light (EL) and the illumination light A plurality of first blades (330a, 330c) having both side end portions (380b) extending in a direction intersecting with the longitudinal direction, and a second end portion defining the other long side (L2) in the longitudinal direction of the illumination light (380c) and a plurality of second blades (330b, 330d) having both side end portions (380d) extending in a direction intersecting with the longitudinal direction of the illumination light, and the plurality of first blades rotate with each other at both side end portions. A first connection part (332a) that can be connected to each other, and a second connection part (332b) that rotatably connects each of the plurality of second blades at both end portions, and the first connection part and the second connection. And, with respect to the longitudinal direction of the illumination light, and to be placed in different positions.
The plurality of first blades (330a, 330c) and the plurality of second blades (330b, 330d) have substantially the same size, and the first connection part (332a) and the second connection part (332b). ) Means that the first blade and the second blade are shifted by approximately half the length in the longitudinal direction of the illumination light (EL).
Further, the number of the first blades (330a, 330c) and the number of the second blades (330b, 330d) are made different.

  According to a second aspect of the present invention, in the illumination device (121) that irradiates an object to be illuminated with slit-shaped illumination light (EL), the variable slit device (100) of the first invention is used as a device for adjusting the shape of the illumination light. It was made to be used. According to the present invention, when uneven illuminance occurs in the illumination light, the uneven illuminance can be corrected easily and reliably.

  In the third invention, the mask and the substrate are relatively scanned in a direction substantially orthogonal to the longitudinal direction of the illumination light while irradiating the substrate (W) with the slit-shaped illumination light (EL) through the mask (R). Thus, in the exposure apparatus (EX) that exposes the pattern formed on the mask onto the substrate, the illumination apparatus (121) of the second invention is used as the illumination apparatus that irradiates the mask with illumination light. According to the present invention, the exposure unevenness is corrected at high speed and accurately, the uniformity of the line width formed on the substrate is improved, and the occurrence of line width defects can be reduced.

  In addition, based on the information related to the illuminance unevenness of the illumination light (EL) and the information related to the illuminance unevenness, the illuminance of the illumination light in the direction substantially orthogonal to the longitudinal direction of the illumination light is determined during relative movement. An arithmetic unit (221) for obtaining at least one of the shape of one long side (L1) of the illumination light and the shape of the other long side (L2) of the illumination light so as to be substantially uniform, and Based on the calculation result, the control device (220) that controls the driving of the plurality of first blades (30a, 330a) and / or the plurality of second blades (30b, 330b), uneven accumulation of illuminance light Can be corrected accurately.

  In addition, a calculation unit (221) that obtains at least one of the shapes of the other long side (L2) of the illumination light (EL) based on information on the line width of the pattern formed on the substrate (W), and a calculation unit With the control device (220) that controls the driving of the plurality of second blades (30b, 330b) based on the result of the calculation, it is possible to reliably correct the line width of the pattern formed on the substrate. It becomes.

  In addition, if the information on the line width of the pattern formed on the substrate (W) includes the amount of change in the line width due to the unevenness of the film thickness of the photosensitive agent applied on the substrate, the unevenness in the illumination light is positively affected. As a result, even if the film thickness of the photosensitive agent applied on the substrate is uneven, the line width of the pattern formed on the substrate can be reliably corrected.

  In addition, the measurement unit (230) measures information on the illuminance unevenness of the illumination light (EL) when the mask (R) is replaced, and the control device (220) displays the pattern formed on the replaced mask on the substrate ( Before the exposure to (W), the driving of the plurality of first blades (30a, 330a) and the plurality of second blades (30b, 330b) is controlled, and a pattern is exposed to each of the plurality of exposure regions on the substrate. In each case, which controls the driving of the plurality of second blades, the line width of the pattern on the entire substrate can be corrected, and the line width of the pattern can also be corrected for each exposure region.

  According to a fourth aspect of the present invention, in the device manufacturing method including the lithography step, the exposure apparatus (EX) of the third aspect is used in the lithography step. According to this invention, since the line width defect of the pattern resulting from uneven illuminance is suppressed, a device having a fine pattern can be efficiently manufactured.

  According to the variable slit device of the present invention, the slit shape of the illumination light can be finely controlled, and unevenness in illuminance can be corrected more appropriately.

  Furthermore, according to the exposure apparatus of the present invention, when uneven illuminance occurs in the illumination light, the uneven illuminance can be corrected easily and reliably.

  Further, according to the exposure apparatus of the present invention, the uniformity of the line width formed on the substrate can be improved, and the occurrence of line width defects can be reduced. Furthermore, throughput can be improved. This is particularly effective when forming a fine pattern.

  Furthermore, according to the device manufacturing method of the present invention, a line width defect of a pattern due to uneven illuminance can be suppressed, so that a device having a fine pattern can be efficiently manufactured. Furthermore, it is possible to efficiently achieve an increase in the capacity of the semiconductor memory and an increase in the speed and integration of the CPU processor.

  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.

  First, illumination light emitted from a light source (not shown) passes through a shaping optical system and is shaped into rectangular illumination light.

  The variable slit device 100 changes the width in a direction substantially orthogonal to the longitudinal direction of the illumination light EL shaped into a rectangular shape (hereinafter, referred to as a short direction), and has a slit shape having a desired slit width. The illumination light EL is formed. The variable slit device 100 includes a first light shielding unit 10 that shields a part of the passing illumination light EL in order to define one long side L1 of the slit illumination light EL, and the other of the slit illumination light EL. In order to define the long side L2, the second light shielding part 20 that shields a part of the passing illumination light EL, the actuator part 50 that drives the first light shielding part 10, and the actuator that drives the second light shielding part 20 Part 60. That is, the variable slit device 100 arbitrarily shields both the long sides L1 and L2 in the longitudinal direction of the passing illumination light EL by driving the actuator units 50 and 60, and the first light shielding unit 10 and the second light shielding unit. The width of the illumination light EL passing through the opening (gap) M with the portion 20 in the short direction is partially changed.

  Therefore, the first light-shielding part 10 and the second light-shielding part 20 form a slit-shaped illumination light EL having a slit width S that is partially changed. Note that both short sides of the illumination light EL are defined by two blades (not shown).

Incidentally, the short direction of the illumination light EL and Y ₀ direction, the illumination light EL longitudinal and X ₀ direction.

  The first light shielding unit 10 includes a plurality of first blades 30a, and the plurality of first blades 30a are driven independently of each other. The plurality of first blades 30a are arranged in a plane orthogonal to the optical axis of the illumination light EL, and are arranged without a gap in the plane. The first blade 30a includes a linear edge portion (first end portion) 80a that defines one long side L1 of the slit-shaped illumination light EL, and a pair of side sides (both end portions) orthogonal to the long side L1. 80b.

  The second light shielding unit 20 includes a plurality of second blades 30b, and the plurality of second blades 30b are driven independently of each other. The plurality of second blades 30b are arranged in a plane orthogonal to the optical axis of the illumination light EL, and are arranged without a gap in the plane. The second blade 30b includes a linear edge portion (second end portion) 80c that defines the other long side L2 of the slit-shaped illumination light EL, and a pair of side sides (both end portions) orthogonal to the long side L2. 80d.

The edge portions 80a and 80c of the first and second blades 30a and 30b are formed with a thickness of about 10 μm. This is to the position of the optical axis direction to cut off the illumination light EL of the slit (Z ₀ direction) exactly matched.

  FIG. 2 is a diagram illustrating the first light shielding unit 10, FIG. 2A is a diagram in which two blades 30 a are connected, and FIG. 2B is a cross-sectional view taken along a line P-P in FIG. FIG. 2C is a diagram illustrating the operation of the blade 30. In addition, since the 2nd light shielding part 20 is comprised similarly to the 1st light shielding part 10, description is abbreviate | omitted.

The first light shielding portion 10 is configured by rotatably connecting both side end portions 80b of the plurality of first blades 30a. First light-shielding portion 10, a plurality of first blade 30a in the optical axis direction (Z ₀ direction) are linked alternately superimposed on upper and lower stages. The blade 30a has a blade 30a disposed on the upper side of the figure, the blade 30a (hereinafter referred to as adjacent blades 30a ') arranged on the lower side there are the, _{X 0} direction and the _{Y 0} direction size respectively Have substantially the same shape. Moreover, since each blade 30a is heated by the illumination light EL, it is formed of a heat-resistant material, for example, a metal such as stainless steel, iron, or copper alloy.

  And the connection part 32a for connecting with the adjacent braid | blade 30a 'is provided in the both-sides edge part of each braid | blade 30a. The connecting portion 32a is configured by overlapping the through holes formed in the blade 30a and the adjacent blade 30a ′ and fitting the pin-shaped members 33 provided with bearings, whereby the blades 30a are mutually connected. It is rotatably connected.

And rod 72, 72a, 72b of actuator parts 50 and 60 mentioned below is connected with pin-like member 33 of each connecting part 32a. Thus, the rod 72, 72a, by moving arbitrary distance in the lateral direction of the illumination light EL respective 72b _{(Y 0} direction), the connecting portion 32 is moved in the _{Y 0} direction, each blade 30a to each other Rotates to define one long side L1 of the illumination light EL.

  The second light-shielding part 20 is configured in the same manner as the first light-shielding part 10, and the plurality of second blades 30b included in the second light-shielding part 20 have the other long side L2 of the illumination light EL with the connecting part 32b as a rotation axis. Is specified.

Accordingly, it is possible to partially change the slit width S of the illumination light EL that passes through the gap between the light shielding units 10 and 20, that is, the opening M of the variable slit device 100.
The mounting of the actuator portion 50, 60 movable table movable not shown _{Y 0} direction, the actuator unit 50 and 60, also moving the first light-shielding portion 10 and the second light-shielding portions 20 in the _{Y 0} direction Is possible.

Returning to FIG. 1, the first and second light shielding portions 10 and 20 are arranged to face each other with the illumination light EL interposed therebetween. In order to shield the long sides L1 and L2 of the slit-shaped illumination light EL, the first light shielding part 10 is composed of eight blades 30a, and the second light shielding part 20 is composed of nine blades 30b. . Further, the locations where the shapes of the first and second light-shielding portions 10 and 20 are changed, that is, the connecting portions 32 of the first and second light-shielding portions 10 and 20 (9 locations for the light-shielding portion 10 and 10 for the light-shielding portion 20). position) is in the longitudinal direction of the illumination light EL (X ₀ direction), the blades 30a, shifted by X ₀ direction length approximately half the length of the 30b, are arranged to be staggered.

  The actuator unit (drive mechanism, first drive member) 50 includes a plurality of linear actuators 70a and rods 72 and 72a connected to the linear actuators 70a. The linear actuator 70a can linearly move the rods 72 and 72a by an arbitrary distance in the axial direction thereof. That is, the power of the linear actuator 70a is transmitted to each connecting part 32a of the first light shielding part 10 through the rod 72a.

  The actuator unit (driving mechanism, second driving member) 60 includes a plurality of linear actuators 70b and rods 72 and 72b connected to the actuators 70b. The linear actuator 70b can linearly move the rods 72, 72b by an arbitrary distance in the axial direction thereof. That is, the power of the linear actuator 70b is transmitted to each connecting portion 32b of the second light shielding portion 20 through the rod 72b.

  These linear actuators 70a and 70b function as drive elements, and for example, a voice coil motor or the like is used.

  Further, the plurality of rods (drive shafts) 72, 72a, 72b are alternately arranged with the longitudinal direction of the illumination light EL interposed therebetween in a plane orthogonal to the optical axis of the illumination light EL. That is, the drive positions of the plurality of first blades 30a and the drive positions of the plurality of second blades 30b are configured not to face each other across the longitudinal direction of the illumination light EL.

  Therefore, as the places where the slit width S of the illumination light EL is partially changed, nine drive positions of the plurality of first blades 30a defining one long side L1 of the illumination light EL are provided, and the other of the illumination light EL is provided. There are ten driving positions of the plurality of second blades 30b that define the long side L2. The driving position of the first blade 30a and the driving position of the second blade 30b are arranged at equal intervals.

  Since the actuator units 50 and 60 are configured in the same manner, the actuator unit 50 will be described below, and the description of the actuator unit 60 will be omitted.

The rod 72a includes a distal end portion 74a attached to the first blade 30a, an attachment portion 75a attached to the linear actuator 70a, and a connection portion 73a connecting the distal end portion 74a and the attachment portion 75a. The connecting portion 73a is, for example, formed of an elastic member such as a leaf spring, and its plate surface is arranged parallel to the optical axis of the illumination light EL (Z ₀ direction). Thus, the connection portion 73a is curved, the tip portion 74a of the rod 72a is movable in the _{X 0} direction.

Thus, the rod 72a, to movable in the distal end portion 74a of 72b in the X ₀ direction is because as a structure in which is rotatably connected to each other a plurality of blades in drive position. That is, as shown in FIG. 2 (c), for example, one of the connecting portion 32a' of the first blade 30a when to [Delta] Y ₀ moves in the _{Y 0} direction, the first blade 30a as the rotation axis and the other of the connecting portion 32a since rotational movement connecting portion 32a' would be moved by [Delta] X ₀ to _{X 0} direction. That is, when rotating the first blade 30a, since the respective connecting portions 32a are thus also moved minutely in the X ₀ direction, each rod 72a is a mechanism that can follow the movement of the X ₀ direction of the connecting portion 32a It is necessary to prepare.

Incidentally, the rod 72, so that the starting point of movement in the X ₀ direction of each blade 30, is the X ₀ direction comprises a stiffness so as not to bend.

  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. 3 is a schematic diagram showing the illumination optical system 121 and the exposure apparatus EX. In the present embodiment, an illumination optical system 121 will be described as an example of the illumination device.

  The exposure apparatus EX is formed on the reticle R by relatively moving the reticle (mask) R and the wafer (substrate) W in a one-dimensional direction while irradiating the reticle R with illumination light (exposure light) EL. A scanning exposure apparatus of a step-and-scan system that transfers a pattern (circuit pattern or the like) onto the wafer W via the projection optical system PL, a so-called scanning stepper. 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 irradiates the wafer W with the light source 120, the illumination optical system 121 that irradiates the reticle R with the illumination light EL from the light source 120, the reticle stage RS that holds the reticle R, and the illumination light EL that is emitted from the reticle R. Projection optical system PL, wafer stage WS that holds wafer W, main control system 220 that controls the overall operation of 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, illumination light having a wavelength range of about 120 nm to about 200 nm, for example, ArF excimer laser (wavelength: 193 nm), fluorine (F ₂ ) laser (157 nm), krypton (Kr ₂ ) laser (146 nm), argon A device that generates (Ar ₂ ) laser (126 nm) or the like is used. In this embodiment, an ArF excimer laser is used as illumination light.

  In addition, the light source 120 is provided with a light source control device (not shown), and this light source control device has an oscillation center wavelength and a spectrum half-value width of the emitted illumination light EL according to an instruction from the main control system 220. Control, pulse oscillation trigger control, etc.

  The illumination optical system 121 irradiates the 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 illumination light EL emitted from the light source 120 is deflected by the deflecting mirror 130 and enters the 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 illumination light EL emitted from the variable dimmer 131 is deflected by the optical path deflection mirror 132, and then sequentially passes through the first fly-eye lens 133, the zoom lens 134, the vibration mirror 135, and the like, and the second fly-eye lens 136. Is incident on.

  On the emission side of the second fly-eye lens 136, a revolver 137 for switching an 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 aperture stop, the size of the light beam applied 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 ring-shaped aperture stop (band zone stop) for band illumination, and a modified aperture stop in which a plurality of openings are arranged eccentrically for a modified light source are provided. The revolver 137 is rotated by a driving device such as a motor, and any one of the aperture stops is selectively disposed on the optical path of the illumination light EL, whereby the shape and size of the secondary light source on the pupil plane is an annular zone, It is limited to small circle, large circle, 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 illumination light EL.

Further, the illumination light EL that has passed through 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.
A variable slit device 100 is disposed in the vicinity of the illumination field stop 141. More specifically, as shown in FIG. 3, the first light-shielding unit 10 and the second light-shielding unit 20 included in the variable slit device 100 are located at a position conjugate with the reticle R pattern (strictly, near the conjugate position). Arranged to change the slit width S of the illumination light EL. The first light shielding unit 10 and the second light shielding unit 20 can be displaced in the optical axis direction of the illumination optical system 121. 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 illumination light EL applied to the reticle R and the wafer W is changed, and the first light shielding unit 10 and the second light shielding unit 10 By moving the light shielding unit 20 in the optical axis direction of the illumination optical system 121, the blur width of the peripheral portion of the illumination light EL irradiated to the reticle R and the wafer W can be adjusted.

  The illumination light EL that has passed through the illumination field stop 141 and the variable slit device 100 is 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. Through the reticle R.

  Thereby, an illumination region (exposure field) having the same shape as the opening M of the variable slit device 100 is formed on the reticle R.

  The reticle stage RS is provided directly below the illumination optical 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 a reticle stage in which a plurality of refractive optical elements (lenses) made of fluoride-doped quartz or fluoride crystals such as fluorite and lithium fluoride are sealed with a projection system housing (lens barrel 169). It is provided directly under the RS. The projection optical system PL reduces the illumination light EL emitted through the reticle R by a predetermined projection magnification β (β is, for example, ¼), and converts the image of the pattern on the reticle R into a specific region (on the wafer W). Image in the shot area). Each optical element constituting the projection optical system PL is supported by the projection system housing via a holding member (not shown), and each holding member holds the peripheral portion of each optical element.

When vacuum ultraviolet rays such as an F ₂ laser are used as the illumination light EL, fluorite (CaF ₂ crystal), quartz glass doped with fluorine, hydrogen, or the like is used as an optical glass material with good transmittance. Magnesium halide (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 the refractive optical element. Therefore, the refractive optical element and the reflective optical element (reflecting mirror) are A combined catadioptric system may be employed.

  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. At the end of the wafer stage WS on the −Y side, a Y moving mirror 152 made of a plane mirror is extended in the X direction. A measurement beam from a Y-axis laser interferometer 151 arranged substantially perpendicularly to the outside is projected onto the Y moving mirror 152, and the reflected light is received by the Y-axis laser interferometer 151. Is detected. Further, the X position of the wafer W is detected by an X-axis laser interferometer (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.

  Wafer stage WS is levitated and supported on the floor surface via a counterweight (not shown) and a plurality of air pads (not shown) which are non-contact bearings. Therefore, according to the law of conservation of momentum, for example, the counterweight moves in the −X direction and the −Y direction according to the movement of the wafer stage WS in the + X direction and the + Y direction. As described above, the counterweight moves to cancel the reaction force accompanying the movement of the wafer stage WS and to prevent the change in the position of the center of gravity.

  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 (control device) 220 controls the exposure apparatus EX in an integrated manner, and includes a calculation unit 221 that performs various calculations and a storage unit 222 that records various types of information.

  For example, the exposure operation for transferring the image of the pattern formed on the reticle R to the shot area on the wafer W is repeatedly performed by controlling the positions of the reticle stage RS and the wafer stage WS.

  In addition, the actuator units 50 and 60 of the variable slit device 100 are instructed to control the shapes of the light shielding units 10 and 20 so as to equalize the integrated exposure amount.

  By the way, the illumination light EL, that is, the ArF excimer laser light, is affected by absorption by oxygen molecules, organic substances, etc. (hereinafter referred to as a light-absorbing material), so that the light-absorbing material existing in the space through which the illumination light EL passes is reduced. The illumination light EL needs to reach the upper surface of the wafer W with sufficient illuminance.

  Therefore, the space through which the illumination light EL 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, and these optical paths are vacuumed. It is filled with a low-absorbing gas (for example, an inert gas such as nitrogen, helium, argon, neon, krypton, or a mixed gas thereof) having a characteristic that absorbs less light in the 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.

  A reticle stage RS for holding the reticle R is provided in a space between the casing 162 containing the illumination field stop imaging optical system and the projection optical system PL.

  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.

  Then, oblique incidence for detecting the position (focus position) and the tilt angle of the wafer stage WS holding the wafer W via the wafer holder 180 and the surface of the wafer W in the Z direction is applied to the image plane side of the projection optical system PL. A type autofocus sensor 181, an off-axis alignment sensor 182, a surface plate 183 on which the wafer stage WS is placed, and the like are provided.

  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 system (not shown) so that a low-absorbency gas is supplied into each space and a light-absorbing substance is discharged to the outside.

  Next, a description will be given of 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 illumination optical system 121, and the exposure apparatus EX having the above-described configuration. To do.

  First, the reticle R and the wafer W are mounted on the reticle stage RS and the wafer stage WS, respectively, and the reticle R is irradiated with the illumination light EL from the illumination optical 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, while irradiating the reticle R with the slit-shaped illumination light EL, the reticle R and the wafer W are moved relative to each other in the direction of the slit width S of the illumination light EL in the opposite directions, 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 the illumination light EL irradiated to the reticle R has uneven illumination, 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 in a semiconductor device, it is necessary to make the integrated exposure amount by the illumination light EL uniform. Such illumination unevenness is considered to occur due to a change in transmittance of each optical element constituting the illumination optical system 121 and the projection optical system PL.

  Here, the principle of correcting uneven exposure due to uneven illumination will be described. FIG. 4 is a diagram for explaining illuminance unevenness of illumination light, etc. FIGS. 4A to 4D show forms of illuminance unevenness, and FIGS. 4E to 4H are those illuminance unevenness. It is a figure which shows the shape of the opening M of the variable slit apparatus 100 for correct | amending, ie, the shape of the passage area of the illumination light EL formed by the light-shielding parts 10 and 20. FIG.

  The illumination light EL is usually formed in a slit shape, and a slit-shaped illumination area is formed on the wafer W by irradiating the wafer W via the reticle R. By scanning the reticle R and the wafer W in the slit width S direction of the 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 illumination light EL is uniform and the scanning speed is constant, the integrated exposure amount of the illumination light EL in the direction orthogonal to the scan direction is uniform, and the shot area on the wafer W is uniform. Should be exposed.

However, in practice, the illuminance of the illumination light EL is often uneven. For example, as shown in FIG. 4A, the illuminance of the illumination light EL with respect to the center P of the slit-shaped illumination area. but the right is higher than the proper value, the left (-X ₀ side) becomes such a state occurs low. When exposure processing is performed with such non-uniform illumination light EL, the left side of the shot area is so-called overexposed and the left 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 non-uniformity of the illumination light EL 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 illumination light EL is reduced in order to reduce the exposure amount. That is, a part of the slit width S is narrowed. Conversely, in areas where the illuminance is lower than the appropriate value (underexposure), the area irradiated with the illumination light EL is increased in order to increase the exposure amount. That is, a part of the slit width S is widened. That is, the variable slit device 100 adjusts a part of the slit width S so that the integrated exposure amount of the illumination light EL in the direction orthogonal to the scanning direction is adjusted to be substantially uniform.

  In the example described above, when the illuminance uniformity of the illumination light EL as shown in FIG. 4A occurs, the slit width S on the left side is narrowed as shown in FIG. Then, the light shielding portions 10 and 20 of the variable slit device 100 are driven so as to widen the left slit width S. Thereby, the exposure amount on the right side decreases, while the exposure amount on the left side increases, so that the exposure unevenness caused by the unevenness of the illumination light EL can be corrected.

  4E to 4H show a case where the shape of the long side on one side of the illumination light EL is changed. When changing the shape of the long sides on both sides, the slit width S may be the same as that when the shape of the long side on one side is changed.

  For the illuminance unevenness of the illumination light EL, in addition to the low-order unevenness component (including primary unevenness or inclination unevenness) in which the illuminance changes at a constant ratio from the right to the left as in the example described above, higher order There are uneven ingredients. For this higher order unevenness component, secondary unevenness (FIG. 4 (b)) in which the illuminance changes to a radiation form, quaternary curve shaped fourth order unevenness (FIG. 4 (c)), or illuminance unevenness is random. Random irregularities (FIG. 4 (d)) and the like.

  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. 4 (e)). 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. 4F to 4H in accordance with the illuminance distribution state. By correcting the amount substantially uniformly, it is possible to suppress the occurrence of uneven exposure due to uneven illumination.

  The variable slit device 100 is not limited to correcting exposure unevenness due to uneven illumination. For example, as will be described later, when the film thickness of the photoresist is uneven, it is possible to change the slit width S of the variable slit device 100 according to the uneven film thickness. That is, in the region where the thickness of the photoresist is thick, the exposure amount is increased by widening the slit width S, while in the region where the film thickness is thin, the exposure amount is reduced by narrowing the slit width S. 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 illuminance or the like will be described.
First, the exposure amount of the illumination light EL is measured by the illuminance meter 230. As shown in FIG. 3, the illuminance meter 230 is provided on the wafer stage WS that holds the wafer W, and when measuring the illuminance in the exposure region of the illumination light EL irradiated on the wafer W, The projection optical system PL is arranged in the vicinity of the position conjugate with the pattern of the reticle R (image plane of the projection optical system PL). The size of the light receiving surface of the illuminance meter 230 may be formed larger than the exposure area irradiated on the wafer W, and the illuminance unevenness in the exposure area may be measured. The size of the light receiving surface may be formed smaller than the exposure area irradiated on the wafer W, and the illuminance meter 230 may scan the exposure area to measure the illuminance unevenness in the exposure area. . Then, the measurement result of the exposure amount (illuminance unevenness) using the illuminance meter 230 is sent to the main control system 220.

  Instead of using the illuminometer 230, the test pattern is exposed on the wafer W using the test reticle on which the test pattern is formed instead of the reticle R on which the circuit pattern is formed. The exposure amount may be indirectly measured by actually measuring the line width of the test pattern on W. Further, it is desirable to measure the line width on the wafer W at a plurality of locations in at least one shot area. Further, the correction value of the slit width S is desirably obtained according to the position where the illumination light EL is irradiated in the shot area.

Thus, by measuring the line width of the test pattern actually formed on the wafer W, the line width error due to causes other than the illuminance unevenness of the illumination light EL (for example, resist coating unevenness on the wafer W) is reduced. Corrections can be made collectively.
Note that the illuminance unevenness in the exposure region is measured when the exposure apparatus is started up, during maintenance, or when exposure conditions are set when the wafer W is exposed. The exposure conditions include, for example, illumination conditions for illuminating the reticle R (setting of an aperture stop), the numerical aperture of the projection optical system, the sensitivity of the resist applied on the wafer W, and the like. Further, the unevenness of illuminance may be measured for each shot area, for each wafer W, or for each lot.

Next, the main control system 220 to which the exposure amount measurement result is sent instructs the actuator units 50 and 60 of the variable slit device 100 based on the measurement result to change the shapes of the light shielding units 10 and 20. That is, the edge portion 80c of the edge portion 80a and the blades 30b of each blade 30a from the initial state of being arranged parallel to the X ₀ direction to adjust the tilt amount to be inclined at a predetermined angle. As described above, the amount of inclination of each blade is determined according to the form of uneven illuminance.

The linear actuator 70 of the actuator portion 50, 60 is driven, the rod 72, 72a, is moved in the direction _{(Y 0} direction) towards and 72b to the illumination light EL, connection of each blade 30 of the light shielding portion 10, 20 part 32a is a rod 72, 72a, according to the amount of movement of the 72b, it moves in the _{Y 0} direction. At this time, the rod 72a, the rod 72 other than 72b is curved in the _{Y 0} direction according to the rotation of each blade 30. Therefore, although the deviation between the linear actuator 70 in the Y ₀ direction position of the connecting portion 32 occurs, the shift amount can be obtained by calculation from the length of the blade 30 and the moving amount of the linear actuator 70. That is, since the inclination amount from the initial state of the edge portion 80a of each blade 30a and the edge portion 80c of each blade 30b can be obtained, it is possible to change the shape of the slit-like illumination light EL to a desired shape. is there.

  In addition, the portions where the shape of the slit width S of the illumination light EL is changed, that is, the connecting portions 32a and 32b of the light shielding portions 10 and 20 are arranged to be staggered across the longitudinal direction of the illumination light EL. Therefore, the slit width S of the illumination light EL can be substantially finely controlled about twice as compared with the case where the light shielding portions 10 and 20 are arranged symmetrically.

  As described above, by changing the shape of the slit width S of the illumination light EL finely, the exposure unevenness due to the uneven illumination can be corrected, and a pattern with a uniform line width can be formed on the wafer W. .

  Note that the slit width is controlled not only by rotating each blade 30a and each blade 30b but also by using a moving table (not shown) as described above, the actuator units 50 and 60, the first light shielding unit 10 and the second light shielding unit. Movement with the unit 20 may be used in combination.

  It is also possible to correct the illuminance unevenness for each shot area formed on one wafer W. In this case, for example, before the wafer is exposed, the edge portions 80a of the blades 30a of the first light shielding unit 10 are corrected by the first light shielding unit 10 so as to correct the secondary or higher irregularities excluding the primary irregularities. Set the amount of tilt from the initial state. The setting of the tilt amount is not changed until the exposure of one wafer W or a plurality of wafers W is completed. In addition, the amount of inclination from the initial state of the edge part 80c of each blade 30b of the second light shielding part 20 is set so that the first unevenness is corrected by the second light shielding part 20. By setting the inclinations of the blades 30a and 30b in this way, the primary unevenness can be reliably corrected for each shot area.

  Further, as described above, the reticle R can be illuminated under illumination conditions such as a ring zone, a small circle, a large circle, or a fourth. Therefore, the shape (slit width) of the illumination light EL set once for each illumination condition is stored in the main control system 220 so that the illumination light EL is shaped every time the illumination condition is changed. The light shielding portions 10 and 20 of the variable slit device 100 may be driven.

In addition, for each illumination condition, a movement amount for moving the first light shielding unit 10 and the second light shielding unit 20 of the variable slit device 100 in the optical axis direction of the illumination optical system 121 is stored in the main control system 220. Alternatively, it may be driven so that the blur width of the peripheral edge of the illumination light EL is optimized every time the illumination condition is changed. This is because the blur width of the peripheral portion of the slit-shaped illumination region irradiated on the reticle R and the wafer W changes with the change of the illumination condition. In particular, when the blur width (width of the long sides L1 and L2 of the slit-shaped illumination light EL) in the peripheral portion in the direction (X direction) orthogonal to the scan direction (Y direction) changes, the illuminance uniformity in the scan direction in the shot region It becomes difficult to maintain the characteristics within an allowable range.
Therefore, in the present embodiment, as described above, each time the illumination condition is changed, the first light-shielding part 10 and the second light-shielding part 20 are moved in the optical axis direction, and the blur width of the peripheral part can be set optimally. I am doing so. The minimum exposure pulse number for exposing one shot area is obtained from the relationship between the optimal blur width, exposure amount, and illuminance uniformity, and the exposure for actually exposing the shot area is obtained. The number of pulses can be set to be equal to or greater than the determined minimum number of exposure pulses, and the accuracy of the integrated exposure amount and illuminance uniformity with respect to the wafer W can be maintained.

In the embodiment described above, the case where the line width of the pattern is made uniform by correcting the uneven illuminance by the variable slit device 100 and suppressing the uneven exposure is described. However, there is a case where the line width of the pattern is made uniform by positively generating unevenness in illuminance by the variable slit device 100 and performing non-uniform exposure. For example, when the film thickness of the photoresist applied on the wafer W is not uniform, uneven illuminance is generated in accordance with the uneven film thickness.
In a region where the thickness of the positive photoresist is thick, the exposure is increased by increasing the slit width S. On the other hand, in a region where the film thickness is thin, the exposure is reduced by decreasing the slit width S. It is possible to suppress the defect (non-uniformity) in the line width of the pattern due to the unevenness of the resist film thickness.

In the following, a specific operation of the variable slit device 100 when correcting a line width defect (non-uniformity) of a pattern caused by a cause other than uneven illuminance will be described.
A photoresist is applied onto the wafer W prior to exposure. The photoresist is a photosensitive resin, and there are a negative type in which a portion irradiated with the illumination light EL from the reticle R remains and a positive type in which the irradiated portion is removed. The photoresist is thinly applied to the surface of the wafer W by a coating machine (coater).
The coater is an apparatus for forming a uniform resist thin film on the wafer W by dropping the liquid resist supplied from the nozzle onto the surface of the wafer W fixed to the rotary support and rotating it at high speed. .

However, in practice, it is very difficult to form a uniform resist film on the surface of the wafer W. The film thickness of the resist formed on the wafer W depends on the viscosity of the resist, the type of solvent in the resist, the rotation speed of the coater, and the rotation time. In particular, a resist film having a non-uniform film thickness is formed concentrically from the center of the wafer W due to the resist coating method. That is, the resist film thickness tends to be thicker in the peripheral region than in the central region of the wafer W due to the influence of the surface tension and the like at the edge portion of the wafer W.
When the entire wafer W is exposed when the resist film thickness on the wafer W is non-uniform, the resist is exposed between the thick and thin areas of the resist film (photochemistry) even when the uniform illumination light is irradiated. A difference occurs in the degree of reaction). In other words, the region where the resist is thick is insufficiently exposed and the region where the resist is thin is excessively exposed.

  In the case of a positive resist, the resist is not sufficiently removed in an area where the photosensitivity is insufficient, so that the line width of the pattern becomes narrow. On the other hand, in the area where the photosensitivity is excessive, the resist is removed more than necessary. The line width of becomes thicker. Therefore, the line width of the pattern is thin in the central area of the wafer W, and the line width of the pattern is wide in the peripheral area. In the case of a negative resist, the pattern line width is large in the central region of the wafer W, and the pattern line width is small in the peripheral region.

Further, even when each process of the development / etching process performed after the exposure process is non-uniform, the line width of the pattern becomes non-uniform.
In the development process, a part of the resist on the wafer W subjected to the exposure process is dissolved and removed with an alkaline aqueous solution. That is, the resist on the wafer W is photochemically changed so that the portion irradiated with the illumination light EL (exposure processing) is soluble or insoluble in the alkaline aqueous solution. Therefore, the alkaline aqueous solution is sprayed onto the wafer W from the spray nozzle. Dissolve and remove the soluble part.

The dissolution of the resist is greatly affected by the temperature, concentration, spray pressure, spray angle, and time of the aqueous alkali solution, and the dissolution of the resist often becomes uneven. For example, when the alkaline aqueous solution is sprayed from the peripheral side of the wafer W toward the center, the resist may be insufficiently dissolved in the central region of the wafer W and excessive in the peripheral region.
For this reason, a phenomenon occurs in which the line width of the pattern becomes narrow in a region where the resist is not sufficiently dissolved and removed, whereas the line width of the pattern becomes thick in a region where the dissolution is excessive.

In the etching process, the copper foil portion of the wafer W exposed by the development process is dissolved with an oxidizing aqueous solution to form a pattern. Examples of the oxidizing aqueous solution include a ferric chloride solution and a cupric chloride solution, and the application method of the oxidizing aqueous solution includes a dip method and a spray method.
In the dip etching, there is a phenomenon in which etching proceeds from the periphery of the wafer W toward the center, so that the etching is not uniform in the central region and the peripheral region of the wafer W. In particular, as the wafer W becomes larger, the difference between the central area and the peripheral area becomes larger.
In addition, in the spray etching, the difference in etching between the central region and the peripheral region is small compared to the dip method, but as in the case of the development processing, the etching is not uniform due to the effect of the nozzle effective range covered by the spray nozzle. turn into.
For this reason, for example, in the central region of the wafer W, etching is insufficient and the line width of the pattern becomes thick, and in the peripheral region, the etching is excessive and the line width of the pattern becomes thin. .

FIG. 6 is a diagram schematically showing the distribution of the change amount of the line width of the pattern formed on the wafer W. As shown in FIG. In the drawing, it is assumed that the line width is narrow in the dark color area and the line width is thick in the light color area.
As described above, even if the illumination light EL has no illuminance unevenness, it is formed in each shot region of the wafer W due to each process in the pre-process and post-process (see FIG. 9) of the exposure process. The line width of the pattern to be formed may be non-uniform. Even in such a case, the line width of the pattern can be made uniform by operating the variable slit device 100 as follows.

First, it is not easy to know exactly what causes the non-uniformity of the line width of the pattern and what kind of cause it affects. However, each process in the pre-process and the post-process should be performed substantially uniformly on at least the wafers W in the same lot. That is, the resist film thickness and the state of development / etching treatment are substantially uniform for the wafers W in the same lot.
Therefore, in order to investigate in advance the non-uniformity of the line width of the pattern formed on the wafer W, test exposure is performed using the reticle on which the test pattern is formed or the reticle on which the circuit pattern is formed, and the wafer The line width of the pattern formed on W is measured. In addition, before the test exposure, the first light-shielding unit 10 and the second light-shielding unit 20 are once driven so that the variable slit device 100 is in the initial state, that is, the slit widths are equally spaced. In this initial state, the illuminance meter 230 is used to measure the illuminance distribution in the slit-shaped exposure area irradiated on the wafer. Thereafter, an exposure process is performed with the illumination light EL that has passed through the equally spaced slit widths, a pattern is formed on the wafer W, and the line width distribution is measured.

Based on the illuminance distribution in the slit-shaped exposure area measured before the test exposure, the illuminance unevenness caused by the change in the transmittance of the optical elements constituting the illumination optical system 121 and the projection optical system PL provided in the exposure apparatus is corrected. Therefore, the inclination amount of the edge portion 80a of each blade 30a of the first light shielding portion 10 and the inclination amount of the edge portion 80c of the blade 30b of the second light shielding portion 20 are obtained.
Further, the line width change amount generated for each shot area on the wafer is obtained based on the distribution of the line width change amount of the wafer W obtained by the test exposure. Based on the obtained line width change amount, an inclination amount of the edge portion 80c of the blade 30b of the second light shielding unit 20 for correcting the line width change amount is obtained for each shot region.

  Then, prior to actual exposure processing, the main control system 220 determines the amount of inclination of the edge portion 80a of each blade 30a of the first light shielding unit 10 and the blade of the second light shielding unit 20 based on the measurement result of the illuminance meter 230. The amount of inclination of the edge portion 80c of 30b is adjusted.

Next, in the actual exposure process, the amount of inclination of the edge portion 80c of the blade 30b adjusted in advance according to the result of the distribution of the line width of the test-exposed wafer W for each shot region (measurement result of the illuminometer 230) The amount of inclination obtained for each shot region is added to the amount of inclination of the edge portion 80c of the blade 30b of the second light-shielding unit 20 obtained based on the above, and the integrated exposure amount given for each shot region is adjusted. Thus, the line width defect of the pattern is improved.
For example, the illuminance of the illumination light EL is reduced in the shot area where the line width of the pattern is thin, while the illuminance of the illumination light EL is increased in the shot area where the line width of the pattern is thick. That is, the unevenness of each process in the pre-processing step and the post-processing step of the exposure process is offset by positively generating unevenness of exposure.
Specifically, when the line width of the pattern is not uniform in one shot area as a result of the test exposure, the slit width of the shot area is changed by the variable slit device 100 in the non-scanning direction. To correct the exposure unevenness. On the other hand, unevenness in the scanning direction can be corrected by performing scanning exposure while changing the number of pulses of the illumination light EL, or by performing exposure while changing the moving speed of the wafer stage WS, that is, the scanning speed. it can.

As shown in FIG. 7, when attention is paid to a plurality of shot regions arranged in the non-scan direction (X direction) on the wafer W, for example, in the leftmost shot region, the line width on the left side in the shot is thick and the right side is thin. In the center shot area, the line width becomes thinner overall. In the shot area at the right end, the line width on the left side in the shot is narrow and the right side is thick. In such a case, unevenness can be satisfactorily improved by changing the light-shielding portion 20 of the variable slit device 100 for each shot region when performing stepwise movement in the X direction and sequentially performing exposure.
Specifically, as shown in FIG. 7, in the leftmost shot area, the light shielding unit 20 is driven to make the slit width S of the opening M wide on the left side in the shot and narrow on the right side. In the center shot area, the light shielding portion 20 is parallel and exposed uniformly. In the rightmost shot area, the exposure is performed with the slit width S of the opening M being narrow on the left side in the shot and wide on the right side.

  As described above, by performing the exposure process by causing the variable slit device 100 to act on each shot area on the wafer W, each process of the wafer W is caused by each process in the pre-process and post-process of the exposure process. A situation in which the line width of the pattern formed in the shot region is not uniform can be suppressed, and the line width of the pattern is made uniform.

  When attention is paid to a plurality of shot regions arranged in the scanning direction (Y direction) on the wafer W, the line width of the pattern gradually changes along the Y direction, so that the Y direction does not move stepwise in the X direction. It is also possible to perform the exposure process while moving step by step. In this case, for example, by changing the moving speed of the stage, the oscillation frequency of the laser, the pulse energy of the laser, and the like for each shot region, the unevenness can be suppressed while reducing the change in the shape of the light shielding unit 20. Further, in order to perform the exposure process while moving stepwise in the Y direction, it is necessary to drive the reticle stage RS, the reticle blind of the illumination optical system 121, and the like in a drive sequence different from the step movement in the X direction. In this case, the light-shielding unit 10 does not need to be driven until the exposure of one line in the Y direction is completed.

As described above, according to the variable slit device 100, the first order unevenness and the higher order unevenness can be corrected by the different light shielding portions 10 and 20, respectively. Moreover, the shape of the illumination light EL in the longitudinal direction can be changed in detail to accurately correct higher order unevenness of the illumination light EL. In particular, since the primary unevenness of the illumination light EL can be corrected at high speed by the light shielding unit 20, a fine pattern can be formed accurately without reducing the throughput of the exposure apparatus EX.
In addition, the variable slit device 100 is not limited to suppressing illumination unevenness, and can positively generate illumination unevenness to improve pattern line width defects (non-uniformity) due to causes other than illumination unevenness.

  FIG. 5 is a diagram showing light shielding portions 310 and 320 which are modifications of the light shielding portions 10 and 20. In the light shielding portions 10 and 20 described in the above-described embodiment, the rods 72a and 72b connected to the linear actuators 70a and 70b are connected to the connecting portions 32a and 32b of the two adjacent blades 30a and 30b. The light shielding portions 310 and 320 connect the rods 372a and 372b to the central portions of two adjacent blades (first blades) 330a and 330c and blades (second blades) 330b and 330d, respectively. The connecting portions (first and second connecting portions) 332a and 332b between the blades 330a to 330d are the same as the connecting portions 32a and 32b. The operation of the light shielding units 310 and 320 is the same as that of the light shielding units 10 and 20. In FIG. 5, the linear actuator portions 50 and 60 are omitted. The blades 330a and 330c include a linear edge portion (first end portion) 380a that defines one long side L1 of the slit-shaped illumination light EL, and a pair of side sides (both side ends) orthogonal to the long side L1. Part) 380b. Similarly, the blades 330b and 330d include a linear edge portion (second end portion) 380c that defines one long side L2 of the slit-shaped illumination light EL, and a pair of side sides (both sides) orthogonal to the long side L2. End) 380d.

  Here, in this modification, the blades 330c and 330d at the ends on the long side are longer than the other blades 330a and 330b, and two rods 372a and 372b are connected. This is because it is desired to control the positions of the connecting portions 332a and 332b that connect the blades 330c and 330d and the blades 330a and 330b to desired positions. That is, by controlling the positions of the two rods 372a and 372b connected to the blades 330c and 330d, the positions of the connecting portions 332a and 332b that connect the blades 330c and 330d and the blades 330a and 330b are determined. Thus, if the position of one connecting part 332a, 332b is determined, the position of the adjacent connecting part 332a, 332b is determined by controlling the position of the rods 372a, 372b connected therebetween, and this is repeated. Thus, the positions of all the connecting portions 332a and 332b, that is, the positions of the blades 330a and 330b can be controlled to a desired position. Also in this modified example, the positions of the blades 330c and 330d are not limited to the end portion of the transmission region of the illumination light EL, but may be provided at the central portion, for example, as in the previous embodiment.

  Even with such a configuration, the same effects as those of the previous embodiment can be obtained, and the position of the blade can be controlled with high accuracy.

  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 the above-described embodiment, the case where a so-called chain-type light-shielding portion in which a plurality of blades are rotatably connected to both ends of the light-shielding portion has been described. However, the present invention is not limited to this. As shown in JP 2000-82655 A, a light-shielding portion formed by arranging a plurality of blades in a comb-like shape without a substantial gap may be used. Further, the first light shielding part may be a chain type, and the second light shielding part may be a comb tooth type.

  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), F ₂ 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.

  When a linear motor is used for the wafer stage or reticle stage, either an air levitation type using air bearings or a magnetic levitation type using Lorentz force or reactance force may be used. The stage may be a type that moves along a guide, or may be a guideless type that does not have a guide. Further, when a planar motor is used as the stage driving device, either the magnet unit (permanent magnet) or the armature unit is connected to the stage, and the other of the magnet unit and the armature unit is connected to the moving surface side of the stage ( Base).

  The reaction force generated by the movement of the wafer stage may be released mechanically to the floor (ground) using a frame member as described in JP-A-8-166475.

  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.

Next, an embodiment of a manufacturing method of a micro device using the exposure apparatus and the exposure method according to the embodiment of the present invention in the lithography process will be described.
FIG. 8 is a flowchart showing a manufacturing example of a microdevice (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, or the like).
First, in step S10 (design step), function / performance design (for example, circuit design of a semiconductor device) of a micro device is performed, and pattern design for realizing the function is performed. Subsequently, in step S11 (mask manufacturing step), a mask (reticle) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S12 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.
Next, in step S13 (wafer processing step), using the mask and wafer prepared in steps S10 to S12, an actual circuit or the like is formed on the wafer by lithography or the like, as will be described later. Next, in step S14 (device assembly step), device assembly is performed using the wafer processed in step S13. This step S14 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as necessary. Finally, in step S15 (inspection step), inspections such as an operation confirmation test and a durability test of the microdevice manufactured in step S14 are performed. After these steps, the microdevice is completed and shipped.

FIG. 9 is a diagram illustrating an example of a detailed process of step S13 in the case of a semiconductor device.
In step S21 (oxidation step), the surface of the wafer is oxidized. In step S22 (CVD step), an insulating film is formed on the wafer surface. In step S23 (electrode formation step), an electrode is formed on the wafer by vapor deposition. In step S24 (ion implantation step), ions are implanted into the wafer. Each of the above steps S21 to S24 constitutes a pre-processing process at each stage of the wafer processing, and is selected and executed according to a necessary process at each stage.
At each stage of the wafer process, when the above pre-process is completed, the post-process is executed as follows. In this post-processing process, first, in step S25 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step S26 (exposure step), the circuit pattern of the mask is transferred to the wafer by the lithography system (exposure apparatus) and the exposure method described above. Next, in step S27 (development step), the exposed wafer is developed, and in step S28 (etching step), exposed members other than the portion where the resist remains are removed by etching. In step S29 (resist removal step), the resist that has become unnecessary after the etching is removed. By repeatedly performing these pre-processing steps and post-processing steps, multiple circuit patterns are formed on the wafer.
Moreover, in order to manufacture reticles or masks used not only in micro devices such as semiconductor elements but also in light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., from mother reticles to glass substrates, The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a silicon wafer or the like. Here, in an exposure apparatus using DUV (deep ultraviolet), VUV (vacuum ultraviolet) light, or the like, a transmission type reticle is generally used. As a reticle substrate, quartz glass, fluorine-doped quartz glass, fluorite, Magnesium fluoride or quartz is used. In proximity-type X-ray exposure apparatuses, electron beam exposure apparatuses, and the like, a transmissive mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate. Such an exposure apparatus is disclosed in WO99 / 34255, WO99 / 50712, WO99 / 66370, JP-A-11-194479, JP-A2000-12453, JP-A-2000-29202, and the like. .
Further, the present invention is applied to an immersion type exposure apparatus in which a liquid (for example, pure water) is filled between the projection optical system PL and the wafer as disclosed in, for example, the pamphlet of International Publication WO99 / 49504. can do. The immersion exposure apparatus may be a scanning exposure system using a catadioptric projection optical system.

It is a figure which shows a variable slit apparatus. It is a figure which shows the braid | blade of a light-shielding part. It is a schematic diagram which shows an exposure illumination system and exposure apparatus. It is a figure explaining the illumination intensity nonuniformity of the illumination light for exposure. It is a figure which shows the modification of a light-shielding part. FIG. 3 is a diagram schematically illustrating a line width distribution of a pattern formed on a wafer W. FIG. 6 is a diagram schematically illustrating a distribution of line widths of patterns formed in a plurality of shot regions arranged in the non-scanning direction of a wafer W. It is a flowchart figure which shows an example of the manufacturing process of a microdevice. It is a figure which shows an example of the detailed process of step S13 in FIG.

Explanation of symbols

30a First blade 30b Second blade 50 Actuator section (drive mechanism, first drive member)
60 Actuator (drive mechanism, second drive member)
72, 72a, 72b Rod (drive shaft)
80a Edge (first end)
80c Edge part (second end)
80b, 80d Side, both side ends 100 Variable slit device 121 Illumination optical system (illumination device)
220 Main control system (control device)
221 Calculation unit 230 Illuminance meter (measurement unit)
330a, 330c first blade 330b, 330d second blade 332a connecting portion (first connecting portion)
332b connecting part (second connecting part)
372a, 372b Rod (drive shaft)
380a Edge portion (first end)
380c Edge (second end)
380b, 380d Side (both ends)
EL illumination light L1, L2 Long side R Reticle (mask)
W Wafer (Substrate)
EX exposure equipment

Claims (21)

In a variable slit device for forming slit-shaped illumination light,
A plurality of first blades having a first end defining one long side in the longitudinal direction of the illumination light;
A plurality of second blades having second ends defining the other long side in the longitudinal direction of the illumination light;
The variable slit device, wherein the first blade and the second blade are arranged such that the first end and the second end are shifted from each other in a predetermined position with respect to the longitudinal direction of the illumination light. . The one long side is defined by driving the plurality of first blades at a first driving position that moves the plurality of first blades in a direction perpendicular to the longitudinal direction of the illumination light,
The said other long side is prescribed | regulated by driving in the 2nd drive position which moves these 2nd braid | blades in the direction orthogonal to the longitudinal direction of the said illumination light, It is characterized by the above-mentioned. Variable slitting device. The plurality of first blades and the plurality of second blades have substantially the same size, respectively.
The variable slit device according to claim 2, wherein the first drive position and the second drive position are alternately arranged with the longitudinal direction of the illumination light interposed therebetween.   4. The first drive position and the second drive position are arranged by shifting the first blade and the second blade by approximately half the length in the longitudinal direction of the illumination light. A variable slitting device described in 1. The plurality of first blades and / or the plurality of second blades have both end portions extending in a direction intersecting with a longitudinal direction of the illumination light,
5. The variable according to claim 1, wherein the plurality of first blades and / or the plurality of second blades are rotatably connected at both side end portions. 6. Slitting device. A drive mechanism for driving the plurality of first blades and / or the plurality of second blades;
5. The variable slit device according to claim 2, wherein the first drive position and / or the second drive position is a position of a drive shaft of the drive mechanism. 6. The plurality of first blades and / or the plurality of second blades are rotatably coupled at both end portions extending in a direction intersecting a longitudinal direction of the illumination light,
The variable slit device according to claim 6, wherein the drive shaft of the drive mechanism is disposed at a position where the both end portions are rotatably connected.   The variable slit device according to claim 6 or 7, wherein the drive mechanism moves the plurality of first blades and / or the plurality of second blades in an optical path direction of the illumination light. The plurality of first blades and / or the plurality of second blades are rotatably coupled at both end portions extending in a direction intersecting a longitudinal direction of the illumination light,
The variable slit device according to claim 6 , wherein a drive shaft of the drive mechanism is disposed at a position different from the both end portions of the first blade and / or the second blade . 10. The variable slitting device according to claim 9 , wherein the drive shaft of the drive mechanism is disposed at a center portion of the first blade and / or a center portion of the second blade . The drive mechanism includes a first driving member Before moving the plurality of first blades in the optical path direction of the illumination light,
The variable slit device according to claim 10 , further comprising a second driving member that moves the plurality of second blades in a direction of an optical path of the illumination light. In a variable slit device for forming slit-shaped illumination light,
A plurality of first blades having a first end defining a long side in the longitudinal direction of the illumination light and both side ends extending in a direction intersecting the longitudinal direction of the illumination light;
A plurality of second blades having a second end portion defining the other long side in the longitudinal direction of the illumination light and both end portions extending in a direction intersecting the longitudinal direction of the illumination light;
A first connecting portion that rotatably connects each of the plurality of first blades at both side end portions;
A second connecting part for connecting each of the plurality of second blades so as to be rotatable with respect to each other at both side end parts;
The variable slit device, wherein the first connecting part and the second connecting part are arranged at different positions in the longitudinal direction of the illumination light. The plurality of first blades and the plurality of second blades have substantially the same size, respectively.
Wherein the first connecting portion and the second connecting portion, claim characterized by being staggered by a length substantially half the first blade and the second blade in the longitudinal direction of the illumination light 12 A variable slitting device described in 1. The variable slit device according to claim 12 or 13 , wherein the number of the first blades and the number of the second blades are different. In an illumination device that irradiates an object to be illuminated with slit-shaped illumination light,
As an apparatus for adjusting the shape of the illumination light, the illumination device characterized by variable slit device is used according to any one of claims 14 claim 1. 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 for exposing on a substrate,
An exposure apparatus using the illumination apparatus according to claim 15 as an illumination apparatus that irradiates the mask with the illumination light. A measurement unit for measuring information related to illuminance unevenness of the illumination light;
Based on the information on the illuminance unevenness, at the time of the relative movement, the illuminance of the illumination light in the direction substantially orthogonal to the longitudinal direction of the illumination light is accumulated to be substantially uniform, A calculation unit for obtaining at least one of a shape and a shape of the other long side of the illumination light;
A control device that controls driving of the plurality of first blades and / or the plurality of second blades based on the calculation result of the calculation unit;
The exposure apparatus according to claim 16 , further comprising: Based on information on the line width of the pattern formed on the substrate, an arithmetic unit that obtains at least one of the other long sides of the illumination light; and
A control device for controlling driving of the plurality of second blades based on a calculation result of the calculation unit;
The exposure apparatus according to claim 17 , further comprising: 19. The exposure apparatus according to claim 18 , wherein the information related to the line width of the pattern formed on the substrate includes a line width change amount caused by unevenness of a film thickness of a photosensitive agent applied on the substrate. . The measurement unit measures information on illuminance unevenness of the illumination light when the mask is replaced,
The control device controls driving of the plurality of first blades and the plurality of second blades and exposes a plurality of patterns on the substrate before exposing the pattern formed on the replaced mask to the substrate. 18. The exposure apparatus according to claim 17 , wherein the driving of the plurality of second blades is controlled every time the pattern is exposed to each of the exposure regions. 21. A device manufacturing method including a lithography process, wherein the exposure apparatus according to any one of claims 16 to 20 is used in the lithography process.

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