JP2007207821A - Variable slit device, lighting device, aligner, exposure method, and method of manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an increase of number of blades and correct uneven illuminance. <P>SOLUTION: The variable slit device regulates a lighting light EL formed by an optical element like a slit, and it is provided with a first light shield 10 that has a plurality of blades 30 to regulate one long side of the lighting light EL, and a second light shield 20 to regulate the other long side thereof. A contour shape to regulate a long side of the second light shield 20 is set according to the intrinsic characteristic of an optical element. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable slit apparatus, an illumination apparatus, an exposure apparatus, an exposure method, and a device manufacturing method 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 transfers a pattern formed on the mask onto the substrate, for example, Patent Document 1 and Patent Document 2 As disclosed in Japanese Patent Application Laid-Open No. 2004-218, there has been proposed a variable slit device that partially changes the slit width of illumination light to make the integrated exposure amount uniform.
Japanese Patent Laid-Open No. 10-340854 (FIG. 1) JP 2000-82655 A (FIG. 1)

However, the following problems exist in the conventional technology as described above.
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 driven to partially change the slit width of the illumination light. In order to eliminate uneven exposure due to uneven illumination with high accuracy, use many blades to increase the number of locations where the slit width can be changed (position in the longitudinal direction) and to finely control the slit width of illumination light. Is desirable.
However, as the number of blades increases, the number of actuators increases correspondingly, complicating the control of the actuators, and the time for changing the shape of the illumination light increases, reducing the throughput of the exposure apparatus. There is a problem. Further, the increase in the actuator is accompanied by heat generation, which has a problem of adversely affecting the exposure accuracy of the exposure apparatus.

  The present invention has been made in consideration of the above points, and provides a variable slit device, an illuminating device, an exposure apparatus, an exposure method, and a device manufacturing method capable of correcting illuminance unevenness while suppressing an increase in blades. With the goal.

In order to achieve the above object, the present invention adopts the following configuration corresponding to FIGS. 1 to 7 showing the embodiment.
The variable slit device of the present invention includes a plurality of blades (30) for defining one long side of illumination light in the variable slit device (100) for defining illumination light formed through an optical element in a slit shape. The first light-shielding part (10) having a second light-shielding part (20) that defines the other long side of the illumination light, and the contour shape that defines the long side of the second light-shielding part is It is characterized in that it is set based on the inherent characteristics.

  In general, illuminance unevenness is composed of a combination of a fixed component that occurs based on the intrinsic characteristics of an optical element and that changes little over time, and a variable component that changes over time due to changes in illuminance or optical element characteristics. . In the variable slit device of the present invention, the fixed component of the illuminance unevenness caused by the inherent characteristics of the optical element among the illuminance unevenness can be corrected by the second light shielding part (20). In 10), the fluctuation component of uneven illuminance is mainly corrected. Thereby, according to this invention, it becomes possible to correct | amend uneven illumination intensity effectively, suppressing the increase in the number of blades in a 1st light-shielding part.

  The illumination device of the present invention is the variable slit device (100) described above as a device for adjusting the shape of illumination light in the illumination device (121) that irradiates the object (R) with slit-shaped illumination light. ) Is used.

  Therefore, in the illuminating device of the present invention, an increase in the number of blades in the first light-shielding portion (10) is suppressed, heat generation is suppressed, and illumination light in which uneven illuminance is effectively corrected is illuminated (R). Can be irradiated.

  The exposure apparatus of the present invention irradiates the substrate (W) with the illumination light (EL) formed in a slit shape through the mask (R), and the mask and the substrate are substantially orthogonal to the longitudinal direction of the illumination light. In the exposure apparatus that exposes the pattern formed on the mask onto the substrate by performing relative scanning in the direction in which the illumination is performed, the illumination apparatus (121) described above is used as the illumination apparatus that irradiates the mask with illumination light. It is characterized by.

  Further, the exposure method of the present invention irradiates the mask and the substrate with illumination light while irradiating the substrate (W) with the slit-shaped illumination light (EL) formed through the optical element through the mask (R). A first light-shielding having a plurality of blades for defining one long side of illumination light in an exposure method in which a pattern formed on a mask is exposed on a substrate by relative scanning in a direction substantially perpendicular to the longitudinal direction And a second light-shielding portion having a contour shape that is set based on the intrinsic characteristics of the optical element and that defines the other long side of the illumination light, and is provided in the optical path of the illumination light It is.

  Therefore, in the exposure apparatus and the exposure method of the present invention, by suppressing the increase in the number of blades, it is possible to suppress the decrease in exposure accuracy while suppressing the heat generation and the decrease in throughput.

The device manufacturing method of the present invention is a device manufacturing method including a lithography step, wherein the exposure method described above is used in the lithography step.
Therefore, in the device manufacturing method of the present invention, it is possible to effectively suppress uneven illuminance while suppressing heat generation in the lithography process, and a device having a pattern or the like formed with high accuracy can be obtained.

  In order to explain the present invention in an easy-to-understand manner, the description has been made in association with the reference numerals of the drawings showing one embodiment, but it goes without saying that the present invention is not limited to the embodiment.

  According to the present invention, it is possible to correct illuminance unevenness with a reduced number of blades and actuators, and it is possible to reduce heat generation and shorten the time required to drive the blades, thereby contributing to improvement in exposure accuracy and throughput.

Embodiments of a variable slit apparatus, illumination apparatus, exposure apparatus, exposure method, and device manufacturing method of the present invention will be described below with reference to FIGS.
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 EL ′.
Then, the variable slit device 100 changes the width in the direction (hereinafter referred to as the short direction) substantially orthogonal to the longitudinal direction of the illumination light EL ′ shaped into a rectangular shape, 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 L2 of the slit illumination light EL, and the other of the slit illumination light EL. In order to define the long side L1, 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 blocks the passing illumination light EL by driving the actuator units 50 and 60, and passes through the opening M between the first light blocking unit 10 and the second light blocking unit 20. The width of the illumination light EL 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).
In the following description, the short direction of the illumination light EL is defined as the Yo direction, and the long direction of the illumination light EL is defined as the Xo direction.

The first light shielding unit 10 has a plurality of blades 30, and the plurality of blades 30 are driven independently of each other. The plurality of blades 30 are arranged in a plane orthogonal to the optical axis of the illumination light EL, and are arranged in a comb-like shape without gaps in the plane.
Each blade 30 is formed in a long plate shape, and its longitudinal direction is arranged in parallel to the Yo direction. Moreover, since each blade 30 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. Furthermore, a surface treatment is performed so that the blade 30 can slide while in contact with the adjacent blade 30.

  Further, a linear edge portion is formed at one end portion (the end portion on the illumination light EL side) in the longitudinal direction of each blade 30, and this edge portion is one of the slit-like illumination light EL. The long side L2 is defined and formed in parallel to the Xo direction. Each edge portion is formed to a thickness of about 10 μm. This is for accurately matching the position in the optical axis direction (Zo direction) where the slit-shaped illumination light EL is blocked.

  The other end of each blade 30 in the longitudinal direction is connected to a linear actuator 70 described later via a rod 72. Therefore, by moving each rod 72 by an arbitrary distance in the short direction (Yo direction) of the illumination light EL, each blade 30 moves in the Yo direction, and one long side L2 of the illumination light EL is moved. Stipulate.

  The actuator unit 50 includes the same number of linear actuators 70 as the number of blades 30 and rods 72 connected to the respective linear actuators. As described above, each of the actuators 50 is driven via the rod 72 to drive each linear actuator 70. The blade 30 is moved in the Yo direction. As the linear actuator, for example, a voice coil motor or the like can be used.

The second light-shielding unit 20 is composed of a long plate-like blade 40, and the blade 40 is arranged with its longitudinal direction parallel to the Xo direction.
The blade 40 is made of the same material as the blade 30, and the edge portion on the side of the illumination light EL is formed with a thickness of about 10 μm. The contour shape of the optical element, which will be described later, through which the illumination light EL passes is uneven. It is set based on the inherent characteristics to be given. Details of the contour shape will be described later.

  Then, rods 74a and 74b rotatably connected around the Zo axis at both ends in the longitudinal direction of the blade 40, and the rods 74a and 74b are moved by an arbitrary distance in the short direction (Yo direction) of the illumination light EL. A linear actuator 70 is connected. By moving the two rods 74a and 74b by an arbitrary distance in the short direction (Yo direction) of the illumination light EL, the edge portion of the blade 40 is initialized in a plane substantially orthogonal to the optical axis of the illumination light EL. Can be tilted from the state. That is, the blade 40 rotates around the rotation axis of the rod 74a rotatably connected to the blade 40, or rotates around the rotation axis of the rod 74b rotatably connected to the blade 40. The edge portion of the blade 40 can change the light shielding state of the illumination light EL that passes through, and the illumination light EL can be formed into an arbitrary slit shape.

  The actuator unit 60 includes two linear actuators 70 and rods 74a and 74b connected to the two linear actuators. As described above, the actuators 60 are driven via the rods 74 by driving the linear actuators 70. The blade 40 is moved parallel to the Yo direction or rotated. One of the two rods 74a, 74b is composed of an elastic body (for example, a leaf spring) that can be elastically deformed in the Xo direction, and the tip of the rod 74a, that is, the blade 40 and the like. The connecting portion can be finely moved in the Xo direction. The reason why the tip portion of the rod 74a is configured to be finely movable in the Xo direction is that the blade 40 rotates. That is, when the blade 40 is rotated, both ends connected to the linear actuator 70 are moved in the Yo direction and slightly moved in the Xo direction, so that the rod 74a needs to be configured to be displaceable in the Xo direction. The other rod 74b has such a rigidity that it does not bend in the Xo direction so that it becomes the starting point of movement of the blade 40 in the Xo direction, that is, a rigidity that does not bend when the blade 40 moves in the Yo direction. Prepare.

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. 2 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 R and the wafer (substrate) W in a one-dimensional direction while irradiating the reticle (mask) 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 sequentially passes through the deflection mirror 130, the variable dimmer 131, the optical path deflection mirror 132, the first fly-eye lens 133, the zoom lens 134, the vibration mirror 135, and the like. The light enters the second fly's eye lens 136.
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. The revolver 137 includes, for example, an aperture stop (normal aperture) made of a normal circular aperture, an aperture stop (small σ stop) for reducing a σ value that is a coherence factor made of a small circular aperture, a ring, and the like. A zone-shaped aperture stop (band zone stop) for band illumination and a modified aperture stop in which a plurality of apertures are arranged eccentrically for a modified light source are provided. In the revolver 137, any one of the aperture stops is selectively disposed on the optical path of the illumination light EL, so that the shape and size of the secondary light source on the pupil plane is a ring zone, a small circle, a large circle, or four. Limited to eyes. 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 stop illuminates the illumination field stop (reticle blind) 141 via the condenser lens group 140. The illumination field stop 141 is disclosed in JP-A-4-196513 and US Pat. No. 5,473,410 corresponding thereto. The variable slit device 100 is disposed in the vicinity of the illumination field stop 141. 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). 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 has a plurality of refractive optical elements (lenses) sealed with a projection system housing (lens barrel 169), and is provided directly below the reticle stage 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).

  The wafer stage WS includes a wafer holder 180 that holds the wafer W, an illuminance meter 230 that measures the exposure amount of the illumination light EL, and the like. Wafer holder 180 is supported by wafer stage WS and holds wafer W by vacuum suction. The wafer stage WS can be moved on the surface plate 183 in the XY plane by a driving unit (not shown). Then, a length measurement beam is projected from the laser interferometer 151 to the Y moving mirror 152Y provided at the end of the wafer stage WS on the −Y side, and the reflected light is received by the Y-axis laser interferometer 151Y. The Y position of W 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. Above the wafer stage WS, there are an oblique-incidence type autofocus sensor 181 for detecting the Z-direction position (focus position) and tilt angle of the surface of the wafer W, an off-axis type alignment sensor 182 and the like. Provided.

  The main control system (control device) 220 controls the exposure apparatus EX as a whole, and includes a calculation unit 221 that performs various calculations and a storage unit 222 that records various types of information. For example, the reticle stage RS In addition, by controlling the position of the wafer stage WS and the like, the exposure operation for transferring the pattern image formed on the reticle R to the shot area on the wafer W is repeatedly performed, and the actuator units 50 and 60 of the variable slit device 100 are allowed to perform the exposure operation. The control unit controls the shape and position of the light shielding units 10 and 20 to make the integrated exposure amount uniform.

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.
The reticle R is formed on the reticle R by irradiating the reticle R with the slit-shaped illumination light EL and relatively moving the reticle R and the wafer W in the direction of the slit width S of the illumination light EL in the opposite directions. The pattern is transferred 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.

  Here, the principle of correcting uneven exposure due to uneven illumination will be described. FIGS. 3A to 3H are diagrams for explaining uneven illuminance of illumination light, etc. FIGS. 3A to 3D show forms of uneven illuminance (distribution), and FIG. (H) is a figure which shows the shape of the opening M of the variable slit apparatus 100 for correct | amending these illuminance unevenness, ie, the shape of the passage area of the illumination light EL formed by the light-shielding parts 10 and 20. FIG. Here, in order to explain the principle and the like, in these drawings, the outline of the opening M formed by the light shielding portion 20 is shown by a straight line for convenience.

  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. Then, the reticle R and the wafer W are scanned in the direction of the slit width S of the illumination light EL, whereby 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 in the direction orthogonal to the scan direction becomes uniform, and the shot area on the wafer W is uniformly exposed. Should be done. However, in practice, the illuminance of the illumination light EL is often not uniform. For example, as shown in FIG. 3A, the illuminance of the illumination light EL with respect to the center P of the slit-shaped illumination area. However, the right side is higher than the appropriate value and the left side (−Xo side) is lower. When exposure processing is performed with such non-uniform illumination light EL, the right 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 in the direction orthogonal to the scan direction becomes substantially uniform.

In the example described above, when the illuminance non-uniformity of the illumination light EL as shown in FIG. 3A occurs, the slit width S on the right side is narrowed as shown in FIG. On the other hand, 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.
3E to 3H show a case where the contour shape of the long side on one side of the illumination light EL is changed. When changing the contour 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.

In the illuminance unevenness of the illumination light EL, there are a high-order unevenness component as well as a low-order unevenness component (including primary unevenness or inclination unevenness) in which the illuminance changes at a constant ratio, as in the example described above. The higher-order unevenness component includes secondary unevenness (FIG. 3B) in which the illuminance changes in a radial pattern, quaternary curve-shaped fourth order unevenness (FIG. 3C), or uneven illuminance. Random irregularities (FIG. 3D) and the like generated in
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. 3 (e)). In the case of secondary unevenness, quadratic unevenness, or random unevenness, exposure is performed by changing the slit width S as shown in FIGS. 3F to 3H in accordance with the illuminance distribution. By correcting the amount substantially uniformly, it is possible to suppress the occurrence of uneven exposure due to uneven illumination.

  Among the illumination unevenness components described above, higher order unevenness components such as third order unevenness and fourth order unevenness are caused by the transmittance distribution and the thin film formation state of each optical element constituting the illumination optical system 121 and the projection optical system PL. It is thought to occur. Due to such a cause, higher order unevenness can be treated as a fixed component with little change over time. On the other hand, it is considered that the low-order unevenness component is generated due to a change in illuminance or a secular change in optical element characteristics. For this reason, low order unevenness can be treated as a fluctuation component that changes with time. Thus, in the present embodiment, the light shielding unit 20 including the blade 40 having a fixed contour shape, in which higher-order unevenness, which is difficult to be corrected appropriately unless the number of divisions is increased, is extracted as a fixed component. The low-order unevenness that changes with time is extracted as a fluctuation component, and is corrected by the light shielding unit 10 that includes the plurality of movable blades 30.

Here, a method for setting the contour shape of the blade 40 of the light shielding unit 20 will be described.
First, the illumination conditions are changed a plurality of times (for example, the aperture stop is changed to change the region of the optical element through which the illumination light EL is transmitted), and the illumination light EL is changed for each illumination condition by the illuminometer 230 on the stage WS. Measure the exposure. This exposure amount measurement is performed by driving the stage WS, measuring the illuminance in a matrix form within the illumination area of the illumination light EL, and integrating the measured values at each point along the scanning direction (Yo direction). The size of the light receiving surface of the illuminometer 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. And it decomposes | disassembles into the primary component, the secondary component, and the tertiary component or more from the obtained illumination intensity distribution.

  FIG. 4 is a diagram showing a relationship between the position of the opening measured by changing the illumination condition a plurality of times (here, four times) and the illuminance of the third order component or higher extracted from the illuminance distribution obtained by the measurement. . As shown in this figure, an average value of illuminance corresponding to the position of the opening is calculated from the illuminance distributions I1 to I4 obtained for each illumination condition, and an average illuminance distribution IA is obtained from this calculation result. This distribution is set as the contour shape of the blade 40 as shown in FIG.

Next, a specific 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 corresponding to the illumination condition is measured by the illuminance meter 230, and the measurement result of the exposure amount (illuminance unevenness) is sent to the main control system 220. In the main control system 220 to which the measurement result of the exposure amount is sent, the calculation unit 221 analyzes the measurement result, and determines the illumination unevenness form (primary unevenness, secondary unevenness, random unevenness, etc.) of the illumination light EL. The At this time, the illuminance unevenness of the higher-order component based on the optical element unique characteristics of the illumination optical system 121 and the projection optical system PL is corrected by the contour shape of the blade 40 in the light shielding unit 20, and therefore the illuminance unevenness for each illumination condition. Is the illuminance distributions I′1 to I′4 shown in FIG. 5, which is the difference between the illuminance distributions I1 to I4 and the average illuminance distribution IA.
Then, the shape (slit width S) of the illumination light EL necessary to correct the uneven exposure due to the uneven illumination depending on the illumination conditions to be used is obtained, and further, the shading unit 10 for forming the shape is obtained. The driving amount of each blade 30 is obtained.

Then, the main control system 220 commands the variable slit device 100 based on the obtained blade driving amount to drive the linear actuator 70 of the actuator unit 50 to drive the blade 30 of each light shielding unit 10.
The main control system 220 can also correct the primary component (inclination unevenness) of the illuminance distribution with high occurrence frequency by rotating the blade 40 around Zo.
In this way, the variable slit device 100 is driven in accordance with the illuminance unevenness of the illumination light EL, and the blade 30 is placed in the optical path of the illumination light EL to partially change the slit width S of the illumination light EL.

  Note that the illuminance unevenness in the exposure area is measured when the exposure apparatus is started up, during maintenance, or when exposure conditions are set when exposing the wafer. 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, and the like. Note that the uneven illuminance may be measured for each shot area, for each wafer W, or for each lot.

  As described above, in this embodiment, the blade 40 in the light-shielding unit 20 has a contour shape that corrects higher-order components in the illuminance distribution based on the optical element specific characteristics such as the illumination optical system 121 and the projection optical system PL. Therefore, it is not necessary to drive the blade 30 in the light-shielding portion 10 for this higher-order component, so that unnecessary heat generation can be suppressed, and a decrease in exposure accuracy due to air fluctuation or the like can be suppressed. . In the present embodiment, the light shielding unit 10 only needs to correct the low-order component of the illuminance distribution. Therefore, the number of blades 30 and actuators 70 constituting the light shielding unit 10 can be reduced, and heat generation is suppressed. In addition, the time required for driving the blade can be shortened, and the exposure accuracy and throughput can be improved.

  In the present embodiment, since the primary component of the illuminance unevenness can be easily corrected by rotating the blade 40 of the light shielding unit 20 around Zo, the blades 30 of the light shielding unit 10 are individually driven. As compared with the above, the total driving amount can be reduced, the driving time can be shortened, and the heat generation can be further suppressed and the throughput can be further improved.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above-described embodiment, the contour shape of the blade 40 is set based on the unique characteristics of the four illumination conditions with respect to the unique characteristics of the optical element. However, the present invention is not limited to this, and two or three illumination conditions are used. Or you may set based on five or more illumination conditions. Further, the present invention is not limited to a plurality of illumination conditions. When a single illumination condition is used for a long period of time, a contour shape that corrects illuminance unevenness due to the inherent characteristics of the optical element corresponding to the illumination condition is corrected. A blade may be used.

  In addition, the illuminance distribution of the low-order component described in the above embodiment includes variations due to substrate processing caused by illumination conditions, illuminance, resist film thickness, etc. other than those inherent to the optical element, or variations due to shot exposure. The illuminance distribution of these low-order components can be sequentially corrected by the operation of the light shielding unit 10 as described above.

  In the above embodiment, the illuminance unevenness (illuminance distribution) is measured using the illuminometer 230. However, instead of using the illuminometer 230, a test pattern is used instead of the reticle R on which the circuit pattern is formed. By using the formed test reticle, a test pattern is exposed on the wafer W, and the line width of the test pattern on the exposed wafer W is actually measured to indirectly measure the exposure amount. May be.

In the above-described embodiment, the case where the linear actuator 70 is connected to both ends of the blade 40 in order to rotate the blade 40 of the second light shielding unit 20 has been described, but the present invention is not limited thereto. For example, a rotary actuator such as a motor may be connected to the center of the blade 40 to rotate the blade 40.
In the above-described embodiment, the configuration in which the second light shielding unit 20 includes one blade 40 has been described. However, a plurality of blades having edge portions longer than the blades of the first light shielding unit 10 may be combined. Good. For example, a configuration including two blades, three blades, or four blades may be used. In this case, the contour shape formed by the plurality of blades may be a shape that can correct the intrinsic characteristics of the optical element.
As a linear actuator, a rack and pinion mechanism using a linear motor or a servo motor, a cam mechanism, or the like can be used in addition to a voice coil motor.

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

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

  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. 6 is a flowchart showing a manufacturing example of a micro device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micro machine, 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. 7 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.

Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., from mother reticles to glass substrates and 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, as disclosed in, for example, the pamphlet of International Publication No. WO99 / 49504, 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. 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 schematic diagram which shows an illumination optical system and exposure apparatus. (A)-(h) is a figure explaining the illumination intensity nonuniformity of illumination light. It is a figure which shows the relationship between the position of the opening part measured by changing illumination conditions, and illumination intensity. It is a figure which shows the relationship between the position of the opening part measured by changing illumination conditions, and illumination intensity. 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

EL: illumination light (exposure light), EX: exposure apparatus, L1: other long side, L2: one long side, R: reticle (mask, object to be illuminated), W: wafer (substrate), 10: first Light shielding part, 20 ... second light shielding part, 30 ... blade, 60 ... actuator part (drive device), 100 ... variable slit device, 121 ... illumination optical system (illumination device)

Claims (11)

In a variable slit device that regulates illumination light formed through an optical element into a slit shape,
A first light shield having a plurality of blades for defining one long side of the illumination light;
A second light shielding part that defines the other long side of the illumination light,
The contour shape that defines the long side of the second light shielding part is set based on a characteristic characteristic of the optical element. The variable slit device according to claim 1,
The contour shape is set on the basis of the inherent characteristics under a plurality of illumination conditions. The variable slit device according to claim 2,
The variable slit device, wherein the plurality of illumination conditions are different in a region where the illumination light is transmitted through the optical element. In the variable slit apparatus in any one of Claim 1 to 3,
The contour shape is set based on information relating to an illuminance distribution of the illumination light according to the inherent characteristic. The variable slit device according to claim 4,
The contour shape is set based on a third or higher order component of the illuminance distribution. In the variable slit apparatus in any one of Claim 1 to 5,
A variable slit device comprising: a driving device that rotationally drives the second light-shielding portion about an axis substantially parallel to the optical axis of the illumination light. In an illumination device that irradiates an object to be illuminated with slit-shaped illumination light,
The variable slit apparatus as described in any one of Claims 1-6 is used as an apparatus which adjusts the shape of the said illumination light, The illuminating device characterized by the above-mentioned. The mask is formed on the mask by irradiating the illumination light formed in a slit shape on the substrate through the mask and relatively scanning the mask and the substrate in a direction substantially orthogonal to the longitudinal direction of the illumination light. In the exposure apparatus that exposes the pattern on the substrate,
An exposure apparatus, wherein the illumination apparatus according to claim 7 is used as an illumination apparatus that irradiates the mask with the illumination light. The exposure apparatus according to claim 8, wherein
A measurement unit for measuring information related to illuminance unevenness of the illumination light;
Based on the information on the illuminance unevenness, during the relative scanning, the illuminance of one of the long sides of the illumination light is substantially uniform so that the illuminance of the illumination light in a direction substantially perpendicular to the longitudinal direction of the illumination light is accumulated. An arithmetic unit for obtaining a shape;
A second drive mechanism for driving the first light shielding unit;
An exposure apparatus comprising: a control device that drives and controls the second drive mechanism based on a calculation result of the calculation unit. By irradiating the substrate with slit-shaped illumination light formed through an optical element through a mask, the mask and the substrate are relatively scanned in a direction substantially orthogonal to the longitudinal direction of the illumination light, thereby In an exposure method for exposing the pattern formed on the mask onto the substrate,
A first light-shielding portion having a plurality of blades for defining one long side of the illumination light; and a contour shape that is set based on a characteristic characteristic of the optical element and defines the other long side of the illumination light. An exposure method comprising a step of installing a second light-shielding portion in the optical path of the illumination light. In a device manufacturing method including a lithography process,
A device manufacturing method using the exposure method according to claim 10 in the lithography process.

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