JP4586954B2 - Exposure apparatus, exposure method, and device manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exposure apparatus, an exposure method, and a device manufacturing method, and more particularly, to an exposure apparatus and an exposure method used in a lithography process for manufacturing a semiconductor element and the like, and a device manufacturing method using the exposure method.
[0002]
[Prior art]
Conventionally, in a lithography process for manufacturing a semiconductor element (integrated circuit), a liquid crystal display element, an image pickup element (CCD, etc.) or a thin film magnetic head, a pattern of a mask or a reticle (hereinafter collectively referred to as “reticle”) is used. Projection exposure apparatuses such as steppers that transfer to each shot area on a substrate such as a wafer or a glass plate (hereinafter referred to as “substrate”) via a projection optical system are mainly used.
[0003]
For example, a semiconductor device is manufactured by performing one cycle of resist coating → exposure → development → etching / doping, etc. → resist removal → pretreatment process (oxide film formation, doping, CVD, electrode formation, etc.) a plurality of cycles. The semiconductor element has a three-dimensional structure, and is completed by sequentially stacking the structures generated in one cycle. Individual layers in this multilayer structure are called layers.
[0004]
Conventionally, in a projection exposure apparatus such as a stepper, when performing exposure in the same layer, it is natural to perform exposure in an exposure field under certain conditions except for special exposure such as double-pass light. The design of the device was also made under such an idea. For this reason, in the conventional projection exposure apparatus, a plurality of patterns arranged on a reticle used for exposure of the same layer are transferred under different transfer conditions (for example, numerical aperture (NA)) of the projection optical system. And setting the σ value of the illumination system, etc.) were difficult to transfer onto the substrate.
[0005]
[Problems to be solved by the invention]
Although the conventional integrated circuit (IC) structure and manufacturing method have been considered to meet the constraints caused by the structure of the projection exposure apparatus described above, the following problems are inherently inherent. It can be said that there is room for improving the function and performance of the IC and improving productivity by solving the above.
[0006]
Practical resolution and practical depth of focus of the exposure apparatus can be cited as important factors in forming a pattern on the substrate in the lithography process. The practical resolution and the practical depth of focus are greatly influenced by the pitch and size / shape of the pattern, and also the position of the pattern in the field. The practical resolution and the practical depth of focus are the N.I. A. N. of the illumination optical system. A. Also, it greatly changes depending on the combination of the shape and size of the aperture stop in the illumination optical system (for example, small σ, annular zone, quadrupole, etc.).
[0007]
On the other hand, the resolution and depth of focus required when transferring individual patterns are various and not the same.
[0008]
This means that, when all patterns constituting the IC are transferred, strictly speaking, there are required image forming specifications and optimum exposure conditions therefor.
[0009]
For example, a large N.D. is used for transferring a fine pattern such as a contact hole which requires high resolution. A. An exposure apparatus having the projection optical system is suitable. On the other hand, in the case where the pattern itself is not so fine, such as the pattern arranged immediately above the capacitor, and the flatness of the substrate itself is poor, a deep depth of focus is required for transfer. A. Therefore, it is preferable to perform exposure after increasing the depth of focus. In addition, when a fine isolated pattern such as a gate is formed, super-resolution is often obtained by using exposure using a phase shift reticle or the like together. In this case, the small N.I. A. It is considered that exposure by the above is suitable.
[0010]
However, in reality, it is very difficult to achieve exposure by setting an optimal exposure condition for all patterns in this way as long as a method called projection exposure is employed.
[0011]
As a means for solving this problem by a simple method, patterns having similar optimum exposure conditions are arranged on the same layer. That is, as known by terms such as a critical layer and a non-critical layer, for example, fine patterns that require extremely high resolution are designed in the same layer. As a result, the critical layer has a high N.D. A. It is sufficient to perform high-resolution exposure according to. In this case, a low N.I. A. It is sufficient to perform a large depth of focus exposure according to the above, and such simple use is possible. This means that the exposure apparatus can be effectively used as a result.
[0012]
However, such separation of layers is not necessarily a necessary requirement in semiconductor design, and is often due to the limitation on the exposure apparatus side that exposure conditions cannot be changed in the same layer. In other words, in the conventional technique, even when it is preferable in terms of performance, function, and cost to arrange in the same layer, they have to be arranged in different layers due to manufacturing convenience.
[0013]
Further, in the conventional technique, since only one exposure condition can be selected, a specific pattern among patterns arranged in the same layer is forced to be exposed outside the optimum exposure condition. Alternatively, if such a compromise is inevitably unacceptable, even if the patterns are in the same layer, the optimal exposure conditions are divided for each similar pattern and placed on separate masks. The exposure is divided into a plurality of times and the exposure conditions are switched when the mask is changed. In the former case, the device yield is reduced, and in the latter case, the throughput is reduced. In any case, it has been a factor that significantly reduces device productivity.
[0014]
The present invention has been made under such circumstances, and a first object of the present invention is to improve the disadvantages of the above-described conventional technology, increase the degree of freedom in pattern design for each layer, and improve device productivity. An object of the present invention is to provide an exposure method capable of realizing at least one of them.
[0015]
A second object of the present invention is to provide an exposure apparatus capable of realizing at least one of improvement in freedom of pattern design for each layer and improvement in device productivity.
[0016]
A third object of the present invention is to provide a device manufacturing method that can surely improve the productivity of microdevices.
[0017]
[Means for Solving the Problems]
  The invention according to claim 1 is an exposure apparatus for transferring a pattern formed on the mask onto the object via a projection optical system (PL) by moving the mask (R) and the object (W) synchronously. An illumination optical system (2-8) for illuminating the mask with an energy beam (IL); a driving device (11, 19, 21) for synchronously moving the mask and the object; The pattern transfer condition is changed from the first condition to the second condition in accordance with the position information of the mask while the mask is illuminated by the energy beam and the mask and the object are synchronously moved by the driving device. A transfer condition changing device for controlling the driving device and synchronously transferring the mask and the object while changing the transfer condition of the pattern from the first condition to the second condition by the transfer condition changing device. The speedThe speed of the synchronous movement between the mask and the object corresponding to the first condition and the speed of the synchronous movement between the mask and the object corresponding to the second condition are different from each other.An exposure apparatus comprising: a control device to be changed.
[0018]
In this specification, “mask position information” is a general term for information related to the position of the mask during synchronous movement, and the position of the object that moves synchronously with the mask as well as the position of the mask or the speed obtained by differentiating the position. Or all information that can calculate the position of the mask during synchronous movement by a predetermined calculation, such as speed. In the present specification, “pattern transfer conditions” refers to illumination conditions, conditions related to the projection optical system, and energy amount of an energy beam applied to an object, excluding pattern formation conditions, in a broad sense of exposure conditions. Including all conditions.
[0019]
According to this, while the mask is illuminated by the energy beam from the illumination optical system and the mask and the object are synchronously moved by the driving device, the transfer condition changing device performs pattern transfer conditions according to the mask position information. To change. For this reason, for example, when a pattern region having different transfer conditions is formed on the mask, such as a critical layer region, a non-critical layer region, a middle layer region, or the like along the synchronous movement direction (scanning direction). The pattern transfer conditions are changed according to the position information of the mask, that is, according to the pattern region. Therefore, it is possible to perform exposure, that is, transfer of a pattern onto an object, under suitable or optimum transfer conditions for each pattern region during exposure of the same layer. Therefore, if this is taken into consideration in advance, it is only necessary to divide the patterns that are preferable in terms of performance, function, or cost in the same layer into regions on the same mask. There is no need to design with separate layers. Further, even when patterns having different functions (normally suitable transfer conditions are different) are arranged in the same layer, any pattern in the layer can be exposed under a suitable or optimum exposure condition. It is not necessary to divide the pattern of the same layer onto a plurality of masks and to perform a plurality of exposures (divided exposures) using these masks.
[0020]
As described above, according to the exposure apparatus of the first aspect, it is possible to realize at least one of improvement in freedom of pattern design for each layer and improvement in device productivity.
[0021]
In this case, as in the exposure apparatus according to claim 2, the transfer condition changing device includes a first changing device (20, 24) for changing the numerical aperture (NA) of the projection optical system. Can be. In such a case, the large N.I. A. High resolution exposure and small N.P. A. It is possible to perform exposure under suitable transfer conditions according to the pattern, such as large focal depth exposure.
[0022]
In this case, as in the exposure apparatus according to claim 3, the transfer condition changing device includes a second changing device (4, 4) that changes a light amount distribution on either the pupil plane of the illumination optical system or the conjugate plane. 20, 40). Usually, when the numerical aperture (illumination NA) of the illumination optical system is fixed, the NA of the projection optical system is fixed. A. Is changed, the coherence factor (σ value) is changed. Therefore, for example, the second changing device calculates the light quantity distribution on either the pupil plane of the illumination optical system or the conjugate plane, and the N.I. A. By changing according to the change, it becomes possible to set or maintain the σ value to a desired value. Note that the change in the light amount distribution is performed by changing the illumination N.P. A. This is a concept that includes not only the change of the above, but also the change of the shape of the illumination aperture stop that defines the light quantity distribution on either the pupil plane or the conjugate plane of the illumination optical system.
[0023]
  In each of the exposure apparatuses according to claims 2 and 3, as in the exposure apparatus according to claim 4, the transfer condition changing device includescontrolSynchronous movement of the mask and object by the deviceDepending on the speed changeEnergy of the energy beam irradiated on the objectChange the amountIt may further comprise a third changing device (1, 18, 20)..
[0024]
5. Each exposure apparatus according to claim 1, wherein the transfer condition changing device changes the transfer condition according to a pattern formation state on the mask as in the exposure apparatus according to claim 5. It can be.
[0025]
In each of the exposure apparatuses according to claims 1 to 5, as in the exposure apparatus according to claim 6, the transfer condition changing operation sequence by the transfer condition changing apparatus can be set from the outside. Can do.
[0026]
  The invention according to claim 7 is an exposure method for transferring a pattern formed on a mask onto an object via a projection optical system, and the mask and the object are synchronized with the mask illuminated by an energy beam. A transfer condition changing step of changing the pattern transfer condition from the first condition to the second condition according to the position information of the mask during the synchronous movement; and transferring the pattern according to the position information of the mask While changing the condition from the first condition to the second condition, the speed of the synchronous movement of the mask and the object is changed.The speed of the synchronous movement between the mask and the object corresponding to the first condition and the speed of the synchronous movement between the mask and the object corresponding to the second condition are different from each other.A speed changing step for changing the exposure method.
[0027]
According to this, the mask and the object are moved synchronously while the mask is illuminated by the energy beam, and the pattern transfer condition is changed according to the positional information of the mask during the synchronous movement. For this reason, for example, when a pattern region having different transfer conditions is formed on the mask, such as a critical layer region, a non-critical layer region, a middle layer region, or the like along the synchronous movement direction (scanning direction). The pattern transfer conditions are changed according to the position information of the mask, that is, according to the pattern region. Therefore, it is possible to perform exposure, that is, transfer of a pattern onto an object, under suitable or optimum transfer conditions for each pattern region during exposure of the same layer.
[0028]
Therefore, according to the exposure method of the seventh aspect, for the same reason as in the case of the exposure apparatus of the first aspect, improvement in the degree of freedom in pattern design for each layer and improvement in device productivity can be achieved. At least one of them can be realized.
[0029]
In this case, as in the exposure method according to the eighth aspect, the change in the transfer condition may include a change in the numerical aperture of the projection optical system.
[0030]
In this case, as in the exposure method according to claim 9, the change of the transfer condition is a change in the light amount distribution on either the pupil plane of the illumination optical system that illuminates the mask with the energy beam or the conjugate plane. Further, it can be included.
[0031]
  In each of the exposure methods according to claim 8 and 9, as in the exposure method according to claim 10, the change of the transfer condition is performed by synchronous transfer between the mask and the object.DynamicspeedIn response toEnergy of the energy beam irradiated on the objectChange the amountIt may be further included.
[0032]
In each of the exposure methods according to claims 7 to 10, as in the exposure method according to claim 11, in the transfer condition changing step, the transfer condition is changed according to a pattern formation state on the mask. It can be.
[0033]
  A twelfth aspect of the present invention is an exposure method for transferring a plurality of different patterns on a predetermined region on an object in a superimposed manner via a projection optical system, the first mask having a first pattern formed thereon, With the first patternIs differentA mask stage on which the first mask and the second mask are placed, and the object so that the second mask on which the second pattern is formed and the object are relatively scanned with respect to the energy beam. While transferring synchronously in a predetermined scanning direction, when the transfer target pattern to be transferred onto the object is switched from the first pattern to the second pattern during the synchronous movement, the transfer condition is transferred to the first pattern. The first condition is changed to a second condition for transferring the second pattern, and the speed of the synchronous movement is changed while the transfer condition is changed from the first condition to the second condition.The speed of the synchronous movement between the mask and the object corresponding to the first condition and the speed of the synchronous movement between the mask and the object corresponding to the second condition are different from each other.A first exposure step of changing and transferring the first pattern and the second pattern to two regions arranged in the scanning direction on the object via a projection optical system; and in the first exposure step, the first exposure step; And a second exposure step of transferring a pattern different from the pattern transferred in the first exposure step on at least one of the two regions to which the first pattern and the second pattern are transferred respectively. It is an exposure method.
[0034]
According to this, in the first exposure step, while the mask stage and the object are synchronously moved in the predetermined scanning direction, the transfer condition is changed according to the changed pattern during the change of the transfer target pattern during the synchronous movement. And the pattern of the first mask and the pattern of the second mask are successively transferred by the scanning exposure method to two regions arranged in the scanning direction on the object. That is, in the first exposure step, the transfer of the patterns of the two masks, that is, the exposure of the two areas (shot areas) on the object is performed during a series of operations in which the mask stage and the object are moved synchronously in a predetermined direction. Therefore, it is possible to perform continuous scanning exposure for two areas, which has been difficult in the past, and at least acceleration of the mask stage and the object between the areas and reduction of deceleration time compared to the case where scanning exposure is performed for each area. And throughput can be improved accordingly.
[0035]
In the second exposure step, the first mask pattern and the second mask pattern are transferred onto the object, and the first pattern and the second pattern are transferred in the first exposure step, respectively. Of these, a pattern different from the pattern transferred in the first exposure step is transferred and superimposed on at least one region.
[0036]
In addition, in the second exposure step, regarding the region where the pattern transferred from the pattern transferred in the first exposure step is transferred, the overlapping of the patterns having different transfer conditions is performed by, for example, double exposure and each pattern. It can be easily realized by appropriately setting the transfer conditions at the time of transfer. For this reason, it is possible to perform exposure under suitable or optimal exposure conditions for patterns having different functions (usually different transfer conditions). Further, the double exposure described above simultaneously increases the depth of focus and improves the resolution. It can also be realized.
[0037]
As described above, according to the exposure method of the twelfth aspect, it is possible to improve the productivity of the device by improving the throughput and the yield.
[0038]
In this case, as in the exposure method according to claim 13, in the second exposure step, the mask stage is configured such that the first and second masks and the object are scanned relative to an energy beam. In addition, the transfer condition can be changed according to the pattern after the switching while the object to be transferred is synchronously moved in a predetermined scanning direction and the transfer target pattern during the synchronous movement is being switched. In such a case, also in the second exposure step, the two shot areas on the object can be exposed during a series of operations for moving the mask stage and the object in the scanning direction. The acceleration and deceleration time between the mask stage and the object between the regions can be reduced, and the throughput can be improved accordingly.
[0039]
In each of the exposure methods according to claims 12 and 13, as in the exposure method according to claim 14, in the first exposure step, the step of transferring the first and second patterns to the object; The process of moving the object is alternately repeated, and the first pattern and the second pattern are transferred to a plurality of sets of two sets on the object. In the second exposure process, The step of transferring the first and second patterns to the object and the step of moving the object are alternately repeated, and the region of the region where the first pattern and the second pattern are transferred in the first exposure step. For each group, a pattern different from the pattern transferred in the first exposure step may be transferred in at least one region. For example, by performing double exposure by shifting the plurality of regions in the second exposure by one region in the scanning direction with respect to the plurality of regions on the object in the first exposure step, pattern images of different pattern regions They can overlap each other on the object.
[0040]
The invention described in claim 15 is a device manufacturing method including a lithography process, wherein the exposure method according to any one of claims 7 to 14 is used in the lithography process. It is.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
<< First Embodiment >>
A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to the first embodiment. The exposure apparatus 100 is a step-and-scan type scanning exposure apparatus, that is, a so-called scanning stepper.
[0042]
The exposure apparatus 100 irradiates a reticle R as a mask on which a pattern is formed with an energy beam IL, and transfers the pattern of the reticle R onto a wafer W as an object via a projection optical system PL. And a main controller 20 that controls the exposure apparatus main body 102 as a whole.
[0043]
The exposure apparatus main body 102 includes an ArF excimer laser (oscillation wavelength 193 nm), a KrF excimer laser (oscillation wavelength 248 nm), or F as an energy beam source.₂A pulse laser light source (hereinafter referred to as “light source”) 1 such as a laser (oscillation wavelength 157 nm), an illumination optical system (2 to 8) constituting an illumination system together with the light source 1, an energy beam (hereinafter referred to as “exposure”). Reticle stage RST as a mask stage for holding reticle R illuminated by IL), projection optical system PL for projecting exposure light IL emitted from reticle R onto wafer W, and wafer W It includes a wafer stage WST as a substrate stage that moves in an XY two-dimensional plane, a chamber 10 that accommodates the above-described components except for the light source 1 and the like.
[0044]
The light source 1 is actually arranged in a service room with a low degree of cleanness different from the clean room in which the chamber 10 that houses the components of the exposure apparatus main body 102 excluding the light source 1 is installed. Are connected via a routing optical system (light transmission optical system). As the light source, an ultra-high pressure mercury lamp that generates an ultraviolet bright line (g-line, i-line, etc.), a harmonic generator of a copper vapor laser or a YAG laser, or the like may be used.
[0045]
The light source 1 includes a laser resonator, a beam monitor, a laser controller, a high-voltage power supply, and the like (all not shown). The beam monitor monitors the optical characteristics of the pulsed light from the laser resonator. During normal light emission, the laser controller uses a high-voltage power supply so that the detection value of the energy amount output from the beam monitor becomes a value corresponding to the target value of energy per pulse given from the main controller 20. Feedback control of power supply voltage. The laser controller also changes the oscillation frequency (repetition frequency) by controlling the energy supplied to the laser resonator via a high voltage power source. That is, the laser controller sets the oscillation frequency of the light source 1 to the frequency instructed from the main control device 20 according to the control information from the main control device 20, and the energy intensity per pulse in the light source 1 is the main control. Feedback control of the power supply voltage of the high-voltage power supply is performed so that the value is instructed from the device 20 (that is, a value within the allowable value range of the energy intensity variation). Such details are disclosed in detail, for example, in JP-A-8-250402.
[0046]
In addition, a shutter for shielding the exposure light IL in accordance with control information from the main controller 20 is also arranged in the light source 1.
[0047]
The illumination optical system includes an illuminance uniformizing optical system 2, an illumination system aperture stop plate 4, a relay lens 3, a reticle blind 5, a relay lens 6, a bending mirror 7, a condenser lens 8, and the like.
[0048]
The illuminance uniforming optical system 2 is, for example, a beam shaping optical system, an energy coarse adjuster, an optical integrator (a fly-eye lens, an internal reflection type integrator, or a diffractive optical element) sequentially arranged on the optical path of the exposure light IL. In the present embodiment, a fly-eye lens is used. Therefore, the fly-eye lens is hereinafter also referred to as a “fly-eye lens”) (not shown).
[0049]
More specifically, the beam shaping optical system shapes the cross-sectional shape of the incident exposure light IL that is pulsed by the light source 1 so as to be efficiently incident on a fly-eye lens provided behind the optical path. For example, a cylinder lens or a beam expander.
[0050]
Further, the energy coarse adjuster is arranged on the optical path of the exposure light IL behind the beam shaping optical system, and for example, the transmittance (= 1−attenuation rate) can be switched from 100% to multiple stages in a geometric series. It can be done. The switching of the transmittance of the energy coarse adjuster is performed by the main controller 20 via a driving device (not shown).
[0051]
The fly-eye lens is disposed on the optical path of the exposure light IL emitted from the energy coarse adjuster, and in order to illuminate the reticle R with a uniform illuminance distribution, a large number of point light sources (light source images) are formed on the exit-side focal plane. Forming a surface light source, that is, a secondary light source.
[0052]
The illumination system aperture stop plate 4 is disposed on the exit-side focal plane of the fly-eye lens (corresponding to the pupil plane of the illumination optical system) or in the vicinity thereof. The illumination system aperture stop plate 4 is made of a disk-like member, and is formed at an approximately equal angular interval, for example, an aperture stop made of a normal circular aperture, an aperture stop made of a small circular aperture, for reducing the coherence factor σ value, An annular aperture stop for annular illumination, a modified illumination aperture stop formed by decentering a plurality of openings for the modified light source method, and the like are arranged. In this case, the main controller 20 drives the illumination system aperture stop plate 4 via the drive system 40 so that one of the aperture stops can be selectively set on the optical path of the exposure light IL. That is, by selecting and setting the aperture stop of the illumination system aperture stop plate 4, at least one of the light amount distribution of the exposure light IL on the pupil plane of the illumination optical system, specifically, the size and arrangement of the secondary light source can be changed. It has become.
[0053]
Although not shown, the illuminance uniformizing optical system 2 includes a zoom optical system that changes the cross-sectional shape of the exposure light IL incident on the fly-eye lens on the light source 1 side from the fly-eye lens. An optical unit is provided, and the main controller 20 controls the optical unit according to the switching of the aperture stop of the illumination system aperture stop plate 4 so as to suppress the light amount loss due to the change in the illumination condition of the reticle R. It has become.
[0054]
A beam splitter 12 having a small reflectance and a large transmittance is arranged on the optical path of the exposure light IL emitted from any one of the aperture diaphragms 4 on the illumination system aperture stop plate 4. Further, a fixed reticle blind 5A is arranged on the rear optical path. A relay optical system including relay lenses 3 and 6 is disposed with a reticle blind 5 including a movable reticle blind 5B interposed therebetween.
[0055]
The fixed reticle blind 5A is disposed on a surface slightly defocused from the conjugate surface with respect to the pattern surface of the reticle R, and a rectangular opening that defines the illumination area IAR on the reticle R is formed. In addition, a movable reticle blind 5B having an opening whose position and width in the direction corresponding to the scanning direction is variable is disposed in the vicinity of the fixed reticle blind 5A. By further restricting the illumination area IAR, exposure of unnecessary portions is prevented.
[0056]
On the optical path of the exposure light IL behind the relay lens 6 constituting the relay optical system, a bending mirror 7 that reflects the exposure light IL that has passed through the relay lens 6 toward the reticle R is disposed. A condenser lens 8 is disposed on the optical path of the exposure light IL.
[0057]
Further, an integrator sensor 18 composed of a photoelectric conversion element that receives a part of the exposure light IL via the condenser lens 17 is disposed on the reflected light path of the beam splitter 12.
[0058]
Briefly describing the operation of the illumination optical system configured in this manner, the exposure light IL pulsed from the light source 1 enters the illuminance uniformizing optical system 2. In the illuminance uniforming optical system 2, the exposure light IL is first shaped into a cross-sectional shape so as to be efficiently incident on the rear fly-eye lens by the beam shaping optical system, and then incident on the energy coarse adjuster. . Then, the exposure light IL transmitted through the energy coarse adjuster enters the fly-eye lens. As a result, a surface light source composed of a number of point light sources (light source images), that is, a secondary light source is formed on the exit-side focal plane of the fly-eye lens. The exposure light IL emitted from the secondary light source passes through one of the aperture stops on the illumination system aperture stop plate 4 and then passes through the relay lens 3 to form the rectangular opening of the fixed reticle blind 5A and the movable reticle blind 5B. After passing through the relay lens 6, the optical path is bent vertically downward by the mirror 7, and after passing through the condenser lens 8, the rectangular illumination area IAR on the reticle R held on the reticle stage RST is made uniform. Illumination with a good illuminance distribution
[0059]
On the other hand, the exposure light IL reflected by the beam splitter 12 in the illuminance uniformizing optical system 2 is received by the integrator sensor 18 via the condenser lens 17, and the photoelectric conversion signal of the integrator sensor 18 is not shown. It is supplied to the main controller 20 via the peak hold circuit and the A / D converter.
[0060]
On reticle stage RST, reticle R is fixed, for example, by vacuum suction. Reticle stage RST is arranged on a reticle base (not shown) and can be finely driven in a plane (XY plane) perpendicular to optical axis IX of the illumination optical system (matching optical axis AX of projection optical system PL described later). At the same time, the reticle drive unit 11 scans in a predetermined stroke range in the scanning direction (here, the Y-axis direction which is the horizontal direction in FIG. 1). The reticle R will be further described later.
[0061]
The position (including rotation) of the reticle stage RST in the moving surface is always detected by the reticle laser interferometer 16 through the moving mirror 15 fixed on the upper surface thereof with a resolution of about 0.5 to 1 nm, for example. Position information of reticle stage RST from reticle laser interferometer 16 is sent to main controller 20 via stage control system 19 and this. The stage control system 19 drives and controls the reticle stage RST via the reticle driving unit 11 based on the position information of the reticle stage RST in response to an instruction from the main controller 20.
[0062]
The projection optical system PL is disposed below the reticle stage RST in FIG. 1, and the direction of the optical axis AX (coincidence with the optical axis IX of the illumination optical system) is the Z-axis direction. A refracting optical system comprising a plurality of lens elements arranged at predetermined intervals along the optical axis AX direction is used. The projection magnification β of the projection optical system PL is, for example, 1/5 or 1/4. Therefore, as described above, when the illumination area IAR on the reticle R is illuminated by the exposure light IL, an image (partial) in which the pattern formed on the reticle R is reduced by the projection magnification β by the projection optical system PL. An isometric image) is projected onto a slit-shaped exposure area IA on the wafer W having a resist (photosensitive agent) coated on the surface thereof.
[0063]
In the present embodiment, the numerical aperture N.I. is applied to the pupil plane of the projection optical system PL. A. A pupil aperture stop (also referred to as an NA stop) 24 is provided. As the pupil aperture stop 24, a so-called iris stop is used here. The pupil aperture stop 24 is controlled by the main controller 20 through a drive system (not shown).
[0064]
Wafer stage WST is freely driven in an XY two-dimensional plane (including θz rotation (rotation around the Z axis)) via wafer drive unit 21 including, for example, a linear motor or a planar motor. Wafer holder 25 is provided on wafer stage WST, and wafer W is held by wafer holder 25 by, for example, vacuum suction. The wafer holder 25 is actually mounted on a Z leveling table that can be slightly driven in the Z-axis direction and the tilting direction with respect to the XY plane (the θx direction that is the rotation direction around the X axis and the θy direction that is the rotation direction around the Y axis). It is mounted on. Accordingly, the position and orientation of the wafer W can be controlled in the six degrees of freedom directions of X, Y, Z, θx, θy, and θz. Although not shown, a reference mark plate is provided on a Z leveling table (not shown) whose surface is almost the same height as the surface of the wafer W and on which various reference marks are formed. .
[0065]
Further, the position of wafer stage WST in the XY plane is always detected by wafer laser interferometer 31 through movable mirror 27 with a resolution of about 0.5 to 1 nm, for example. Position information (or speed information) of wafer stage WST is sent to stage control system 19 and main controller 20 via this, and stage control system 19 receives the position information (or speed) in response to an instruction from main controller 20. The wafer stage WST is driven and controlled via the wafer driving unit 21 based on the information.
[0066]
An alignment detection system ALG as an off-axis type mark detection system is installed on the side surface of the projection optical system PL. As this alignment detection system ALG, for example, a so-called FIA (Field Image Alignment) type alignment sensor that measures a mark position by illuminating a mark with broadband light such as a halogen lamp and image-processing the mark image. Is used. This alignment detection system ALG can measure the positions of a reference mark on a reference mark plate (not shown) provided on wafer stage WST and an alignment mark on the wafer in the X and Y two-dimensional directions.
[0067]
Information from the alignment detection system ALG is sent to an alignment control device (not shown). The information is A / D converted by the alignment control device, and the digitized waveform signal is arithmetically processed to detect the mark position. Information on the detected mark position is sent to the main controller 20.
[0068]
As an alignment detection system, for example, a target mark is irradiated with coherent detection light to detect scattered light or diffracted light generated from the target mark, or two diffracted lights (for example, of the same order) generated from the target mark. Alignment sensors that detect and interfere with each other may be used alone or in appropriate combination.
[0069]
The exposure apparatus main body 102 includes an irradiation system 13 and a light receiving system 14 that are integrally fixed to a holding member that holds the projection optical system PL, and includes a focus sensor that measures the position of the wafer W in the Z-axis direction. Yes. As the focus sensor (13, 14), a multipoint focal position detection system disclosed in, for example, Japanese Patent Laid-Open No. Hei 6-283403 is used. The outputs of the focus sensors (13, 14) are supplied to the main control device 20, and the main control device 20 gives an instruction to the stage control system 19, and the Z position and leveling of the wafer holder 25 are set to a Z leveling table (not shown). And so-called focus leveling control.
[0070]
Further, although not shown in FIG. 1, a reticle mark on the reticle R (not shown) is provided above the reticle R via the projection optical system PL disclosed in, for example, Japanese Patent Laid-Open No. 7-176468. And a pair of reticle alignment microscopes comprising a TTR (Through The Reticle) alignment detection system using light having an exposure wavelength for observing the mark and the mark on the reference mark plate at the same time. Detection signals from these reticle alignment microscopes are supplied to the main controller 20 via an alignment controller (not shown).
[0071]
The main controller 20 is constituted by a microcomputer (or workstation) including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), I / O interface and the like. Then, each component of the exposure apparatus main body 102 is comprehensively controlled.
[0072]
The main controller 20 is provided with an input / output device 30. The input / output device 30 includes a keyboard, a pointing device such as a mouse, and a display. Various data are input by the operator via the input / output device 30, and a process program, which is a kind of database for setting exposure conditions, is also created.
[0073]
The main controller 20 controls, for example, synchronous scanning of the reticle R and the wafer W, stepping of the wafer W, exposure timing, and the like so that the exposure operation is performed accurately.
[0074]
Specifically, the main controller 20 controls the position of the reticle stage RST and wafer stage WST based on the measurement values of the laser interferometers 16 and 31, for example, during scanning exposure, while controlling the position of the stage control system 19. An instruction for synchronous movement of reticle stage RST and wafer stage WST is given. In response to this instruction, the stage control system 19 synchronizes with the reticle R being scanned at the speed Vr = V in the + Y direction (or −Y direction) with respect to the illumination area IAR via the reticle stage RST. Laser interference so that the wafer W is scanned through the stage WST in the −Y direction (or + Y direction) at a speed Vw = β · V (β is the projection magnification from the reticle R to the wafer W) with respect to the exposure area IA. The positions and velocities of reticle stage RST and wafer stage WST are controlled via reticle drive unit 11 and wafer drive unit 21, respectively, while monitoring the measurement values of total 16 and 31. As described above, in this embodiment, the reticle driving unit 11, the wafer driving unit 21, and the stage control system 19 synchronize the reticle stage RST and the wafer stage WST in a predetermined direction with respect to the exposure light IL every time exposure is performed. A driving device for driving is configured.
[0075]
Further, at the time of stepping, main controller 20 gives a stepping instruction to stage control system 19 while managing the position of wafer stage WST based on the measurement value of laser interferometer 31. The stage control system 19 controls the position of the wafer stage WST via the wafer drive unit 21 while monitoring the measurement value of the laser interferometer 31 in accordance with this instruction.
[0076]
Further, the main controller 20 monitors the output of the integrator sensor 18 described above in order to give the wafer W the target integrated energy amount (target dose amount) determined in accordance with the exposure conditions and the resist sensitivity during the scanning exposure described above. However, the control information is supplied to the light source 1 to control the oscillation frequency (light emission timing) and the light emission power of the light source 1, or the exposure of the reticle R by controlling the energy coarse adjuster. The amount of light IL (energy amount) is adjusted. In the present embodiment, the main controller 20 controls the pupil aperture stop 24 (and the illumination system aperture stop plate 4) before the start of the scanning exposure and in the middle of the scanning exposure as necessary, as will be described later. The opening / closing operation of the movable reticle blind 5B is controlled in synchronization with the operation information of the stage system.
[0077]
Next, the reticle R used in the present embodiment will be described with reference to FIG. As shown in FIG. 2, the reticle R is formed of a rectangular glass substrate, and one surface (corresponding to the lower surface in FIG. 1) of the glass substrate is surrounded by a light-shielding band ES formed of chromium or the like. A rectangular pattern area PA is formed. The pattern area PA is formed on the lower surface side as described above, but FIG. 2 shows a plan view seen from above for convenience of explanation.
[0078]
The pattern area PA is composed of two areas of a first pattern area PA1 and a second pattern area PA2 along the Y-axis direction that is the scanning direction. Among these, the first pattern area PA1 is a pattern area in which a critical pattern A in which a circuit pattern having a fine line width almost equal to the resolution limit of the exposure apparatus 100 occupies most of the part is formed. The second pattern area PA2 is a pattern area in which a non-critical pattern B composed of a set of circuit patterns having a large line width is formed.
[0079]
Further, the reticle R is separated from the center of the pattern area PA (coincided with the reticle center) located on the boundary line between the first pattern area PA1 and the second pattern area PA2 of the reticle R by the same distance on one side and the other side in the X-axis direction. A pair of reticle alignment marks RM1 and RM2 are formed at a position outside the light shielding band ES. Reticle alignment marks RM3 and RM5 are formed on one side and the other side in the Y-axis direction with respect to reticle alignment mark RM1 at the same distance from reticle alignment mark RM1. Further, reticle alignment marks RM4 and RM6 are formed on one side and the other side in the Y-axis direction with respect to reticle alignment mark RM2 at the same distance from reticle alignment mark RM2. Reticle alignment marks RM3 and RM4 exist on the same X axis and are paired with each other. Similarly, reticle alignment marks RM5 and RM6 exist on the same X-axis and make a pair with each other.
[0080]
Next, the exposure processing operation after the second layer (second layer) on the wafer W performed in the above-described exposure apparatus 100 will be described.
[0081]
As a premise, an exposure condition setting file called a process program is stored in the main control device based on information relating to the reticle R input in advance by the operator via the input / output device 30 and illumination condition and other various exposure condition designation information. 20 and stored in a storage device (not shown). Further, it is assumed that a plurality of shot regions are formed on the wafer W by exposure to the previous layer. In this case, each shot area has a shape and size corresponding to the shape and size of the pattern area PA.
[0082]
Further, at the start of this exposure processing operation, the wafer W is related to the wafer W such as loading of the wafer W onto the wafer stage WST, EGA (enhanced global alignment) type wafer alignment using the alignment detection system ALG. It is assumed that the preparatory work has been completed. The EGA wafer alignment is disclosed in detail in Japanese Patent Application Laid-Open No. 61-44429.
[0083]
When an operator inputs an instruction to start exposure via the input / output device 30, the exposure processing operation is started.
[0084]
First, main controller 20 reads exposure condition data (a part of the process program file) stored in the storage device, and sets exposure conditions based on the read exposure condition data. Specifically, reticle R is loaded onto reticle stage RST via a reticle loader (not shown). In addition, on the basis of the read data, the setting of illumination conditions at the time of transferring the pattern A in the first pattern area PA1 and the setting of other exposure conditions are performed. Here, the setting of the illumination condition includes, for example, a selection setting of an aperture stop on the illumination system aperture stop plate 4. In this case, for example, an annular diaphragm (for example, an annular ratio of 1/2) is selected. In addition, the above-mentioned pupil aperture stop 24 is connected to the N.P. A. Is almost the maximum value, for example, N.I. A. = 0.85.
[0085]
Further, main controller 20 determines N.D. of projection optical system PL during transfer of pattern B in second pattern area PA2 based on the data read out above. A. And information on suitable transfer conditions such as illumination conditions are stored in a temporary storage area in the RAM.
[0086]
Next, in main controller 20, there is a critical pattern area on reticle R based on the read data related to exposure accuracy, for example, information on reticle R (first and second pattern areas PA1, PA2 thereof). As an example, fine mode reticle alignment is performed as follows.
[0087]
That is, main controller 20 gives an instruction to stage control system 19 based on the measurement results of laser interferometers 16 and 31, and applies the reference mark plate on wafer stage WST using the above-described pair of reticle alignment microscopes. A predetermined pair of first reference marks of the formed three pairs of reticle alignment reference marks (hereinafter referred to as “first reference marks”) and a reticle alignment mark (for example, RM1) on the reticle R corresponding thereto. , RM2) are moved to a position where they can be simultaneously observed via the projection optical system PL, and the reticle stage RST and wafer stage WST are moved.
[0088]
Then, main controller 20 detects a relative position (amount of positional deviation) between the predetermined pair of first reference marks and the corresponding pair of reticle alignment marks using a pair of reticle alignment microscopes.
[0089]
Next, the main controller 20 gives an instruction to the stage control system 19 and moves the reference mark plate and the reticle R in synchronization with the Y-axis direction at the projection magnification ratio, so that the other two pairs of the first reference sequentially. The relative position between the mark and the corresponding reticle alignment mark is detected.
[0090]
Then, main controller 20 detects the offset of the positional deviation amount of the projected image of reticle R with respect to the reference mark plate and, consequently, wafer stage WST, from the detection result of the relative positions of these three pairs of first reference marks and the corresponding reticle alignment marks. The rotation angle, the angle deviation in the scanning direction, and the like are calculated, and the calculation result is stored in the storage device. This reticle alignment operation is disclosed in detail in JP-A-7-176468.
[0091]
After the above-described reticle alignment, main controller 20 moves wafer stage WST so that the reference mark plate is arranged directly below alignment detection system ALG, and detects the alignment of the second reference mark on the reference mark plate. A misregistration amount with respect to the detection center of the system ALG is detected, and a so-called base of the alignment detection system ALG is detected based on a detection result of the misregistration amount, a measured value of the laser interferometer 31 at this time, and a design baseline. Calculate the line.
[0092]
When the preparatory operation for exposure of the wafer W is completed in this way, the main controller 20 causes the stage control system 19 to perform the wafer stage WST based on the result of the above-described wafer alignment, the baseline measurement result, and the like. The movement of the reticle stage RST is instructed. As a result, the stage control system 19 controls the wafer drive unit 21 based on the measurement value of the laser interferometer 31 to bring the wafer stage to the scanning start position (acceleration start position) for exposure of the first shot area of the wafer W. At the same time as moving the WST, the reticle driving unit 11 is controlled based on the measurement value of the laser interferometer 16 to move the reticle stage RST to the scanning start position. At this time, based on an instruction from the main controller 20, the stage control system 19 corrects the position of the reticle R so that the amount of positional deviation of the reticle R obtained during the reticle alignment described above is minimized.
[0093]
Next, based on an instruction from the main controller 20, the stage control system 19 starts relative scanning in the Y-axis direction between the reticle stage RST and the wafer stage WST via the drive units 11 and 21. In this case, as an example, reticle stage RST is driven in the + Y direction, and wafer stage WST is driven in the -Y direction. FIG. 3A shows a change in the moving speed Vr (= V) according to the position y of the reticle stage RST in the Y-axis direction after the start of relative scanning of both the stages. 3 shows a change in the energy amount P of the exposure light IL per unit time on the wafer W surface (image plane) corresponding to FIG.
[0094]
In this case, although not shown, the moving speed Vw of wafer stage WST is Vw = β · V.
[0095]
Then, as shown in FIG. 3 (A), the relative scanning start (this time is t₀Both stages RST and WST have their respective first target scanning speeds (scanning speeds) V₁, Β ・ V₁The main controller 20 determines that both the stages RST and WST have reached the synchronous settling state, that is, the reticle stage RST is at the position y.₁(When this time is t₁Then, the first pattern area PA1 of the reticle R starts to be illuminated by the exposure light IL from the light source 1, and the above-described scanning exposure is started.
[0096]
Prior to the start of this scanning exposure, the light source 1 starts to emit light, but the movement of each blade of the movable reticle blind 5B is controlled by the main controller 20 in synchronization with the movement of the reticle stage RST. The irradiation of the exposure light IL outside the upper pattern area is prevented in the same manner as in a normal scanning stepper.
[0097]
Then, the reticle stage RST and the wafer stage WST are synchronously driven in a predetermined direction with respect to the exposure light IL, whereby the pattern A in the first pattern area PA1 is sequentially transferred onto the wafer W.
[0098]
In this way, reticle stage RST is moved to position y.₂(This position is a position a predetermined distance before the exposure end position of the first pattern area PA1).₂) In response to an instruction from the main controller 20, the stage control system 19 starts decelerating both stages RST and WST. During this deceleration, the speed ratio β between the two stages is maintained. Further, as shown in FIG. 3B, main controller 20 controls energy amount P of exposure light IL irradiated onto wafer W in accordance with the speed change of both stages RST and WST during this deceleration. To do. The control of the energy amount P is performed as follows.
[0099]
The integrated energy amount irradiated on the wafer W (one point), that is, the exposure amount (dose amount) S is the length in the scanning direction of the projection area (the above-described exposure area IA) of the illumination area IAR onto the wafer W ( If the so-called slit width is D, the repetition frequency of the light source 1 is f, and the average energy (energy density) of one pulse is p, the following equation (1) can be obtained.
[0100]
S = D · f · p / Vw (1)
Normally, the slit width D is fixed, and the exposure amount S needs to maintain a target exposure amount determined on the basis of the sensitivity of the resist, so that the main controller 20 maintains the above equation (1). As described above, at least one of the repetition frequency f and the average energy p of one pulse is controlled according to the change of Vw = β · V. That is, the main controller 20 gives a command to the light source 1 based on the output of the integrator sensor 18 so that the energy amount P = f · p on the image surface per unit time is constant, P / Vw = constant. Control.
[0101]
Therefore, the transfer accuracy of the pattern A in the first pattern area PA1 is hardly lowered even by the decelerating operation of both stages.
[0102]
Then, the reticle stage RST is at the position y shown in FIG._Three(At this point t_ThreeAt the same time as the transfer of the pattern A is completed, the reticle stage RST has a predetermined minimum set speed V_minThe deceleration until is finished. At this time, wafer stage WST is β · V_minHas been slowed down.
[0103]
Time t when the transfer of the pattern A is completed_ThreeIn the main controller 20, the minimum set speed V with respect to the stage control system 19._min, Β ・ V_minCommand to maintain the speed of both stages RST and WST. As a result, time t_ThreeThereafter, the stage control system 19 causes the speeds of both stages RST and WST to reach the minimum set speed V._min, Β ・ V_minMaintained.
[0104]
In parallel with maintaining the constant-speed synchronization state at the minimum setting speed of both stages RST and WST, in the main controller 20, the second storage unit described above is stored in the temporary storage area in the RAM. The transfer condition is changed with reference to the transfer condition information of the pattern B in the pattern area PA2. Specifically, the pupil aperture stop 24 is set to N.P. A. Is a preset value, for example, N.I. A. = Control is performed so as to decrease to 0.70.
[0105]
A period during which such a transfer condition is changed, that is, N.I. A. = 0.85 → NA = 0.70, and DW (= y in FIG. 3A)_Four-Y_Three), The transfer of the pattern B in the second pattern area PA2 onto the wafer W is started in a state where the both stages WST and RST are in constant speed synchronous movement.
[0106]
Then, the change of the setting of the pupil aperture stop 24 ends (this time is changed to t_FourIn response to an instruction from the main controller 20, the stage control system 19 starts reacceleration of both stages RST and WST. During this acceleration, the synchronized state of both stages RST and WST is maintained, and the amount of energy P on the image plane per unit time is controlled by main controller 20 in accordance with the speed change as described above. .
[0107]
Then, the reticle stage RST is at the position y shown in FIG._Five(At this point t_FiveAnd both stages RST and WST have their respective second target scanning speeds (scanning speeds) V₂, Β ・ V₂To reach.
[0108]
The main controller 20 detects the time t when both stages RST and WST reach the second target scanning speeds._FiveThus, the stage control system 19 is instructed to maintain the speeds of both stages RST and WST at the second target scanning speed. As a result, time t_FiveThereafter, the stage control system 19 maintains the speeds of both the stages RST and WST at the second target scanning speed, and the wafer W of the pattern B in the second pattern area PA2 is in a constant speed synchronous movement state of both the stages WST and RST. The transfer to is continued.
[0109]
In this way, reticle stage RST moves to position y in FIG.₆(At this point t₆And the transfer of the pattern B is completed.
[0110]
Time t above₆Thus, based on an instruction from the main controller 20, the stage control system 19 starts deceleration in the scanning direction of both stages RST and WST. Then, after a predetermined time has elapsed, that is, the reticle stage RST is moved to the starting point y₀To 2y_ThreeOnly when it has moved, the deceleration of both stages is completed. Time t above₆Thus, even if the shutter closing operation in the light source 1 is started, the exposure of the exposure light IL to the reticle R is continued for a predetermined time period when the shutter closing is completed. Therefore, main controller 20 controls the movement of each blade of movable reticle blind 5B in synchronization with the movement of reticle stage RST to prevent exposure of unnecessary portions.
[0111]
As described above, the scanning exposure for the first shot area on the wafer W is completed, whereby the pattern A in the first pattern area on the reticle R and the pattern B in the second pattern area on the first shot area on the wafer W are changed. Reduced transfer is performed adjacent to each other.
[0112]
Here, it is desirable that main controller 20 gives a command to stage control system 19 during the above-described scanning exposure to correct the scanning direction angle error of reticle R obtained during the reticle alignment described above.
[0113]
Thus, when the scanning exposure for the first shot area is completed, stepping between shot areas of wafer stage WST is performed by stage control system 19 via wafer drive unit 21 based on an instruction from main controller 20. The wafer W is moved to the acceleration start position for exposure of the second shot area.
[0114]
Further, in the main controller 20, the transfer of the pattern A in the first pattern area PA1 described above is performed based on the information stored in the temporary storage area in the RAM until the above-described stepping between shot areas is completed. In this case, the exposure condition is set, for example, the pupil aperture stop 24 is set.
[0115]
At the time of the above stepping, the stage control system 19 measures the positional displacement of the wafer stage WST in the X, Y, and θz directions in real time based on the measurement values of the laser interferometer 31 in response to an instruction from the main controller 20. To do. The stage control system 19 controls the wafer drive unit 21 based on the measurement result so that the XY position displacement of the wafer stage WST is in a predetermined state.
[0116]
In parallel with the above-described stepping between shot areas of wafer stage WST, stage control system 19 moves reticle stage RST to the aforementioned relative scanning start position y in accordance with an instruction from main controller 20.₀Return to (see FIG. 3A).
[0117]
At this time, the stage control system 19 controls the reticle driving unit 11 based on the displacement information of the wafer stage WST in the θz direction in accordance with an instruction from the main controller 20, and the rotational displacement error on the wafer W side is determined. The reticle stage RST is rotationally controlled so as to compensate.
[0118]
In this way, when main controller 20 determines that the positioning of the second shot areas of both stages RST and WST to the acceleration start position for exposure has been stabilized, On the other hand, scanning exposure similar to the above is performed.
[0119]
In this manner, the scanning exposure on the shot area on the wafer W and the stepping operation for the next shot area exposure (and the returning operation to the acceleration start point of the reticle (reticle stage)) are repeatedly performed on the wafer W. The pattern of the reticle R is sequentially transferred to all of the exposure target shot areas, and the exposure ends.
[0120]
As is apparent from the above description, in this embodiment, the first numerical aperture (NA) of the projection optical system PL is changed by the pupil aperture stop 24 and the main controller 20 that controls the pupil aperture stop 24. The changing device is configured, and the light source 1 (internal laser controller), the integrator sensor 18 and the main control device 20 perform exposure and irradiation on the wafer at the speed when the reticle R and the wafer W are synchronously moved by the driving device. A third changing device is configured to change the energy amount of the light IL in conjunction with each other. A transfer condition changing device that changes the pattern transfer condition in accordance with the position information of the reticle R is configured including the first changing device, the third changing device, and the like.
[0121]
As described above, according to the exposure apparatus 100 and the exposure method thereof according to the present embodiment, the reticle R is illuminated by the exposure light IL from the illumination optical system (2 to 8), and the stage control system 19 and the drive unit 11, While the reticle R and the wafer W are being moved synchronously via 21, the transfer condition changing device described above changes the pattern transfer condition according to the position y of the reticle R in the scanning direction, for example, N of the projection optical system PL. . A. To change.
[0122]
Here, in the present embodiment, as the reticle R, two pattern regions having different suitable transfer conditions along the synchronous movement direction (scanning direction), that is, the first pattern region PA1 which is a critical pattern region and the non-critical pattern region. A reticle in which the second pattern area PA2 is formed is used.
[0123]
For this reason, the pattern transfer conditions can be changed in accordance with the position of the reticle R, that is, in accordance with the pattern region, during the above-described scanning exposure. Therefore, the patterns A and B in the first and second pattern areas PA1 and PA2 can be transferred onto the wafer W under suitable or optimal transfer conditions for each pattern area during exposure of the same layer.
[0124]
More specifically, the resolving power Rc of the projection exposure apparatus is such that the exposure wavelength is λ, the numerical aperture N.P. A. It is known that the following expression (2) is used.
[0125]
Rc = k1 · λ / N. A. (2)
Here, k1 is a proportionality constant called a process coefficient.
[0126]
The depth of focus DOF is expressed by the following equation (3).
[0127]
DOF = k 2 · λ / (NA)²                  ...... (3)
k2 is a proportionality constant.
[0128]
In the present embodiment, when the pattern A is transferred, which requires a high resolving power, the N.I. A. Is increased to realize high resolution exposure, and when transferring the pattern B requiring a greater depth of focus, the N.I. A. To achieve a large depth of focus exposure. Thus, in this embodiment, it is possible to perform exposure under suitable transfer conditions corresponding to the pattern.
[0129]
That is, paying attention to the transfer condition changing function during the scanning exposure of the exposure apparatus 100 of the present embodiment described above, it is the same when the patterns arranged in the same layer are more preferable in terms of performance, function, or cost. It is only necessary to divide and arrange each area on the reticle. That is, in such a case, it is not necessary to design the layers separately as in the prior art. In addition, even when patterns having different functions (usually different suitable transfer conditions) are arranged in the same layer, any pattern in the layer can be exposed under suitable or optimum exposure conditions, and In addition, it is not necessary to divide the pattern of the same layer described above in the prior art onto a plurality of masks and to perform multiple exposures (divided exposures) using these masks.
[0130]
Therefore, according to the exposure apparatus 100 and the exposure method of the present embodiment, it is possible to improve both the degree of freedom in pattern design for each layer and the improvement of device productivity.
[0131]
Furthermore, in the present embodiment, it is possible to reduce the synchronous movement speed in a state where an appropriate exposure dose is ensured. A. Even when it takes time to change (switch) the transfer conditions such as the above, the switching can be performed smoothly.
[0132]
Furthermore, in the present embodiment, the above-described pattern transfer condition changing operation sequence can be freely set from the outside by the operator via the input / output device 30 when creating the process program. The setting of the pattern transfer conditions can be freely changed according to the pattern used for transfer.
[0133]
By the way, in the above-described embodiment, as a transfer condition for different pattern regions, the N.I. A. However, the illumination conditions of the illumination optical system may be changed. Accordingly, the case of changing the illumination condition will be described. In the above embodiment, not only the critical pattern A but also the non-critical pattern B is transferred while being exposed under annular illumination. When transferring a non-critical pattern, exposure is often performed under illumination conditions such as normal illumination, which are different from the annular illumination. In such a case, the N.D. of the projection optical system PL performed in the section DW in FIG. A. When changing the above, it is necessary to switch the aperture stop of the illumination system aperture stop plate 4. However, if switching of the aperture stop of the illumination system aperture stop plate 4 is performed during the above-described scanning exposure, the exposure light IL may be blocked by the illumination system aperture stop plate 4 almost completely during the switching. In such a case, it is desirable that exposure is not performed during the above switching.
[0134]
As a countermeasure for this, for example, reticle R1 as shown in FIG. 4 may be used in place of reticle R. The reticle R1 is provided with a light-shielding band ES1 having a predetermined width between the first pattern area PA1 and the second pattern area PA2 constituting the pattern area PA.
[0135]
When this reticle R1 is used, main controller 20 may drive reticle stage RST in the scanning direction via stage control system 19 according to a speed change curve as shown in FIG. In FIG. 5A, the horizontal axis is the position in the Y-axis direction. Of course, also in this case, it is necessary to drive wafer stage WST at a speed Vw = β · V. Also in this case, as shown in FIG. 5B, main controller 20 can control energy amount P irradiated onto wafer W per unit time in accordance with the change in the stage speed. desirable.
[0136]
In this case, in both the transfer of the pattern A in the first pattern area PA1 and the pattern B in the second pattern area PA2, the speeds of both stages RST and WST during exposure are set to the maximum speed.
[0137]
As described above, when exposure is performed by the exposure apparatus 100 using the reticle R1 of FIG. 4, it is possible to perform exposure under substantially optimal transfer conditions for each pattern to be transferred. In this case, the illumination system aperture stop plate 4, the drive system 40, and the main control device 20 constitute a second change device that changes the light amount distribution on the pupil plane of the illumination optical system. Then, this second changing device calculates the light quantity distribution on the pupil plane of the illumination optical system by the N.I. of the projection optical system PL. A. It is possible to set or maintain the coherence factor σ value to a desired value by changing according to the change of
[0138]
  In this case, the time t required to switch the illumination system aperture stop plate 4_ch1 and the time t required for the change setting of the aforementioned pupil aperture stop 24_ch2 whichever is longer, T = max (t_ch1, t_ch2) is the minimum set speed V so that the reticle stage RST crosses the width BD (see FIG. 5A) of the light-shielding band ES1 in the scanning direction._minIs preferably set. That is, V_min=BD/ T based on minimum set speed V_minIs preferably set.
[0139]
Further, when the reticle R1 shown in FIG. 4 is used, since exposure is not performed during the transfer condition switching, not only the pattern A transfer to the pattern B transfer but also the pattern B transfer to the pattern A Even when switching to the transfer, the pupil aperture stop 24 and the illumination system aperture stop plate 4 are driven without any problem. Accordingly, it is possible to perform so-called completely alternate scanning exposure in which the scanning directions of reticle stage RST and wafer stage WST are reversed for each shot region.
[0140]
As can be easily imagined from the above description, when the time T is very short, approximately V_min= V_maxTherefore, V = V is always applied during exposure without decelerating reticle stage RST._maxIt is also possible to move with. In this case, it is not necessary to change the energy amount P described above.
[0141]
However, when the pattern area is separated by the light shielding band as in the above-described reticle R1, the area on the wafer W corresponding to the light shielding band becomes an unexposed area, and the chip is obtained from one wafer. Number may decrease.
[0142]
Therefore, when the above-described reticle R is used, an illumination system aperture stop composed of an iris diaphragm similar to the pupil aperture stop 24 described above may be used in place of the illumination system aperture stop plate 4 described above. In this case, the main controller 20 determines the size of the aperture of the illumination system aperture stop in parallel with the change of the pupil aperture stop 24 during the scanning exposure, that is, the N.I. A. (Illumination NA) can be changed. In this case, the illumination system aperture stop and the main controller 20 constitute a second changing device that changes the light quantity distribution on the pupil plane of the illumination optical system.
[0143]
<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the same reference numerals are used for the same or equivalent components as those in the first embodiment described above, and the description thereof is simplified or omitted.
[0144]
In recent years, double exposure has been performed to obtain super-resolution. In this exposure method, a reticle for 1st exposure (referred to as “reticle Rc”) and a reticle for 2nd exposure (referred to as “reticle Rd”) are prepared. This pattern is transferred to each shot area on the wafer W. Next, the reticle used for exposure is changed from the reticle Rc to the reticle Rd, and the pattern of the reticle Rd is transferred to each shot area to which the pattern of the reticle Rc has been transferred, using the optimum transfer conditions for the reticle Rd. .
[0145]
When this double exposure is performed, the reticle Rc pattern and the reticle Rd pattern need to be overprinted on each shot area on the wafer W, so that the reticle can be applied to any layer of one wafer. It is necessary to perform exposure by exchanging Rc and reticle Rd. In order to quickly replace the reticle, a double reticle holder type reticle stage is provided.
[0146]
That is, in the exposure apparatus of the second embodiment, as the reticle stage RST, a double reticle holder type reticle stage capable of simultaneously holding two reticles is provided, and accordingly, an exposure sequence during scanning exposure is provided. As a feature, a so-called completely alternate scan sequence is employed.
[0147]
FIG. 6 schematically shows a plan view of reticle stage RST used in the second embodiment. This reticle stage RST has a rectangular shape elongated in the Y-axis direction, which is the scanning direction, and two reticles Rc and Rd are arranged on the upper surface thereof at predetermined intervals along the Y-axis direction. It is sucked and held via each vacuum chuck.
[0148]
Movable elements 34A and 36A of the pair of linear motors 34 and 36 constituting the reticle driving unit are fixed to both side surfaces of the reticle stage RST in the X-axis direction, respectively. The stators 34B and 36B of the linear motors 34 and 36 are extended along the Y-axis direction and supported by a support member (not shown). In addition, reticle stage RST is levitated and supported on the upper surface of reticle base 38 by a static air bearing (not shown) with a clearance of about several μm.
[0149]
As shown in FIG. 6, a reticle X moving mirror 15X made of a plane mirror is fixed to the + X side end of the upper surface of reticle stage RST. A length measurement beam from a reticle X-axis interferometer (not shown) is irradiated vertically to the X moving mirror 15X. Further, a pair of corner cubes 15Y is provided at the + Y side end of the upper surface of reticle stage RST.₁, 15Y₂Are fixed, and these corner cubes 15Y₁, 15Y₂On the other hand, measurement beams from a pair of reticle Y-axis interferometers (not shown) are respectively irradiated. These length measurement beams are reflected by reflection mirrors 42 and 44 fixed on the reticle base 38, respectively, and the original optical path is turned in the opposite direction and received by the reticle Y-axis interferometer.
[0150]
Then, the position of the reticle stage RST in the Y-axis direction and the θz rotation are always detected by the reticle Y-axis interferometer with a resolution of, for example, about 0.5 to 1 nm with respect to, for example, the reflection mirrors 42 and 44 or other fixed mirrors. Then, the position of the reticle stage RST in the X-axis direction is always detected by the reticle X-axis interferometer with a resolution of, for example, about 0.5 to 1 nm with reference to a predetermined fixed mirror.
[0151]
In this case, the corner cube 15Y is used as a reticle Y-axis interferometer.₁, 15Y₂A length measuring beam is projected onto the corner cube 15Y to receive the respective reflected lights.₁, 15Y₂Since a pair of double-path interferometers that detect the position in the Y-axis direction are used, even if there is θz rotation in the reticle stage RST, the position in the Y-axis direction of the projection position of each measurement beam is accurately detected. be able to.
[0152]
Other components of the apparatus are the same as those of the exposure apparatus 100 of the first embodiment described above.
[0153]
Next, the pattern C on the reticle Rc as the first mask and the pattern D on the reticle Rd as the second mask are overlapped by double exposure on the wafer W by the exposure apparatus of the second embodiment. The operation during transfer will be briefly described. In the present embodiment, it is assumed that the pattern C and the pattern D are patterns to be formed in one layer.
[0154]
As a premise, an exposure condition setting file called a process program is mainly based on information on reticles Rc and Rd input by an operator in advance via the input / output device 30 and information on illumination conditions and other various exposure conditions. It is created by the control device 20 and stored in a storage device (not shown). Further, it is assumed that a plurality of shot regions are formed on the wafer W by exposure to the previous layer. In this case, each shot region has a shape and size corresponding to the shape and size of the pattern region on the reticle Rc (or Rd).
[0155]
Further, at the start of this exposure processing operation, the preparatory work related to the wafer W, such as loading of the wafer W onto the wafer stage WST, EGA type wafer alignment using the alignment detection system ALG, has been completed. Shall.
[0156]
When an operator inputs an instruction to start exposure via the input / output device 30, the exposure processing operation is started.
[0157]
First, main controller 20 reads exposure condition data (a part of the process program file) stored in the storage device, and sets exposure conditions based on the read exposure condition data. Specifically, reticles Rc and Rd are loaded onto reticle stage RST via a reticle loader (not shown). In addition, based on the read data, an illumination condition is set for transferring the pattern C of the pattern area formed on one reticle Rc used for exposure, and other exposure conditions are set. In this case, for example, an annular diaphragm (for example, an annular ratio of 1/2) is selected. In addition, the above-mentioned pupil aperture stop 24 is connected to the N.P. A. Is almost the maximum value, for example, N.I. A. = 0.85. At this time, the main controller 20 stores information on the set preferable transfer conditions, for example, setting information of the pupil aperture stop 24, in the first storage area in the RAM.
[0158]
Further, main controller 20 determines N.D of projection optical system PL when transferring pattern D of the pattern area formed on reticle Rd based on the data read out above. A. And information on suitable transfer conditions such as illumination conditions are stored in a second storage area in the RAM.
[0159]
Next, main controller 20 recognizes that critical pattern areas exist on reticles Rc and Rd based on the read information on reticles Rc and Rd (pattern areas thereof), and the same as described above. Perform fine mode reticle alignment. At this time, in the second embodiment, the relative positions of the reticle alignment mark and the corresponding first reference mark are detected for both the reticles Rc and Rd, and the reference mark is detected based on the detection result of the relative position. As a result, the offset of the displacement amount of the projection image of reticles Rc and Rd relative to wafer stage WST, the rotation angle, the angular displacement in the scanning direction, and the like are calculated, and the calculation result is stored in the storage device.
[0160]
After the above reticle alignment, main controller 20 calculates a so-called baseline of alignment detection system ALG in the same procedure as described above.
[0161]
When the preparatory operation for the exposure of the wafer W is completed in this way, the main controller 20 performs both stages RST and WST via the stage control system 19 in the same procedure as in the first embodiment described above. It moves to the acceleration start position for exposure of the first shot area SA1 on the wafer W. After that, main controller 20 starts relative scanning of both stages RST and WST for driving reticle stage RST in the −Y direction and wafer stage WST in the + Y direction via stage control system 19 in the same manner as described above. The pattern C of the pattern area on the reticle Rc is transferred to the first shot area SA1 on the wafer W by the scanning exposure method (see FIG. 7A).
[0162]
After the pattern C is transferred to the first shot area SA1, the reticle stage RST is continuously scanned in the −Y direction and the wafer stage WST is scanned in the + Y direction. When the pattern D of the reticle Rd enters the illumination area, the second stage The pattern D is transferred to the shot area SA2.
[0163]
At this time, during the scanning movement from the end of the transfer of the pattern C to the start of the transfer of the pattern D, as in the first embodiment described above, the information in the second storage area in the RAM is used. In addition to changing the setting of the aperture stop 24, the speed control in the scanning direction of both stages RST and WST and the control of the amount of energy on the image plane per unit time are performed in the same manner as in the first embodiment.
[0164]
Thus, when the scanning exposure for the second shot area is completed, main controller 20 causes stage control system 19 to move wafer W to the acceleration start position for exposure of third shot area SA3. Give instructions. In response to this instruction, the stage control system 19 performs step-to-shot area stepping of the wafer stage WST via the wafer driving unit 21 in the same procedure as described above, and the wafer is placed at the acceleration start position for exposure of the third shot area SA3. Move W.
[0165]
In this case, since the pattern D is used as shown in FIG. 7A when the third shot area SA3 is exposed, it is not necessary to change the exposure conditions, for example, the setting of the pupil aperture stop 24.
[0166]
In parallel with the above shot area stepping of wafer stage WST, stage control system 19 performs exposure for third shot area SA3 using the pattern of reticle Rd in accordance with an instruction from main controller 20. The reticle stage RST is further moved in the + Y direction by a predetermined distance with the acceleration start position as a target value.
[0167]
Thus, when main controller 20 determines that the positioning of both stages RST and WST to the acceleration start position for the exposure of the third shot area has been settled, both stages RST in the opposite direction to the above are used. , WST relative scanning is started, scanning exposure is performed on the third shot area on the wafer W in the same manner as described above, and the pattern D of the pattern area on the reticle Rd is transferred to the third shot area SA3 (second area on the wafer W). Is transferred to the shot area adjacent to the + X side of the shot area SA2.
[0168]
After the pattern D is transferred to the third shot area SA3, the reticle stage RST is continuously scanned in the + Y direction and the wafer stage WST is scanned in the -Y direction, and the pattern R of the reticle Rc enters the illumination area. The pattern C is transferred to the shot area SA4.
[0169]
At this time, during the scanning movement from the end of the transfer of the pattern D to the start of the transfer of the pattern C, the setting of the pupil aperture stop 24 is changed using the information in the first storage area in the RAM in the same manner as described above. And the speed control in the scanning direction of both stages RST and WST and the control of the amount of energy on the image plane per unit time.
[0170]
In this way, the scanning exposure for the two shot areas arranged in the Y-axis direction on the wafer W and the stepping operation for the next shot area exposure are repeatedly performed, and the reticle R is applied to all of the exposure target shot areas on the wafer W. Are sequentially transferred, and the first exposure is completed. In FIG. 7A, as described above, a plurality of shot areas on the wafer W, for example, from the first shot area SA1 to the sixteenth shot area SA16, the pattern C on the reticle Rc and the pattern on the reticle Rd are shown. D is the transferred state. As can be seen from FIG. 7A, an image of the pattern C (latent image) is formed in the shot areas of the first row and the third row (odd row) as viewed from the + Y side. In the shot area of the fourth row (even-numbered row), an image (latent image) of the pattern D is formed.
[0171]
When the first exposure process for the wafer W is completed, main controller 20 starts the second exposure process immediately, that is, without performing reticle alignment or the like.
[0172]
The second exposure process is basically the same as the first exposure process described above, except that the acceleration start position at the time of exposure for each shot region of the wafer W, that is, the wafer stage WST, is as described above. The difference is that the shot area is set to a position shifted in the + Y direction by the length of the shot area in the scanning direction, and the arrangement of the shot areas in the scanning direction is increased by two lines.
[0173]
As a result, in the second exposure process, the pattern D image is transferred onto the shot area where the pattern C image of each shot area SAi is formed, and is transferred to the shot area where the pattern D image is formed. The pattern C image is transferred in an overlapping manner.
[0174]
FIG. 7B shows a state in which the pattern of the reticle Rc and the reticle Rd is transferred onto the wafer W of FIG. 7A described above by the second exposure process. In FIG. 7B, C and D shown in parentheses indicate the types of patterns formed on the wafer W by the first exposure process. As shown in FIG. 7B, on the wafer W, a pattern is formed on the shot area excluding the shot areas at one end and the other end in the scanning direction, that is, each shot area constituting the above-described shot areas SA1 to SA16. C and pattern D are transferred by double exposure.
[0175]
By the double exposure described above, images of pattern C and pattern D are formed in each of the shot areas SA1 to SA16 on the wafer W, and the wafer W is developed by the developing device. In each shot area, a resist image of pattern C and pattern D to be formed in one layer is formed.
[0176]
FIG. 8A shows the locus on the wafer W of the exposure center (center of the illumination area IA) when exposure is performed as described above. As shown in FIG. 8A, in a normal exposure operation, assuming that the time required to expose one shot is Texp and the time required for stepping is Tstep, in this embodiment, 16 shots are required for exposure. The time can be roughly represented by the following formula (4). In equation (4), the movement time of wafer stage WST in the scanning direction other than during scanning for exposure is ignored. Further, since the acceleration / deceleration of the stages RST and WST is almost unnecessary when switching the transfer pattern in the shot area adjacent to the scanning direction, for example, between the shot areas SA1 and SA2, this time is actually shortened. Is ignored in equation (4).
2 × (4 · 2Texp + 3Tstep) = 16Texp + 6Tstep (4)
[0177]
On the other hand, FIG. 8B shows a locus on the wafer W at the center of exposure in the case of performing the conventional exposure in which stepping is performed for each shot. As shown in FIG. When the exposure operation is performed, the time required for exposure of 16 shots can be roughly expressed by the following equation (5). In Expression (5), the moving time of wafer stage WST in the scanning direction other than during scanning for exposure is ignored.
4 × (4Texp + 3Tstep) = 16Texp + 12Tstep (5)
[0178]
In this case, as can be seen from a comparison between Expression (4) and Expression (5), the total time required for exposure and stepping is shortened in the present embodiment because the number of steppings is smaller.
[0179]
As described above, according to the exposure apparatus and the exposure method of the second embodiment, the main controller 20 causes the patterns C and D and the wafer W to be exposed to the exposure light IL during the first exposure process. The reticle Rc (or Rd) on which the patterns C and D are formed and the wafer W are synchronously moved in the scanning direction (Y-axis direction) so that the transfer pattern during the synchronous movement is switched. The transfer conditions are changed according to the switched pattern, and the patterns C and D are transferred to the plurality of shot areas SA1 to SA16 on the wafer W via the projection optical system PL.
[0180]
Next, main controller 20 performs reticle Rc (or pattern R) (or pattern C, D) so that patterns C, D and wafer W are scanned relative to exposure light IL during the second exposure process. Rd) and the wafer W are moved synchronously in the scanning direction (Y-axis direction), and the transfer condition is changed according to the changed pattern during switching of the transfer pattern during the synchronous movement, and the first exposure process Thus, the patterns D and C on the reticle Rd (or Rc) are transferred onto the plurality of shot regions on the wafer W onto which the patterns C and D on the reticle Rc (or reticle Rd) have been transferred.
[0181]
In this case, in the first exposure, the pattern transfer of the two reticles Rc and Rd, that is, the exposure of the two shot areas on the wafer W, is performed in a series of moving the reticle stage RST and wafer stage WST synchronously in the Y-axis direction. Therefore, part of the movement operation (stepping operation) in the X-axis direction of wafer stage WST performed between the end of exposure of the previous shot and the start of exposure of the next shot can be omitted. It is possible. As a result, compared to the conventional exposure method in which the exposure operation and the stepping operation for one shot region are repeated, it is possible to improve the throughput by a part of the stepping being omitted. Also, in the second exposure, as in the first exposure, the throughput can be improved as compared with the conventional exposure method in which the exposure operation and the stepping operation are repeated.
[0182]
Further, by performing double exposure by shifting the plurality of shot areas in the second exposure with respect to the plurality of shot areas on the wafer W in the first exposure process, patterns of different pattern areas are obtained. The images can be overlapped on the wafer.
[0183]
Therefore, according to the second embodiment, the superposition of the patterns C and D having different transfer conditions on the reticles Rc and Rd is performed by double exposure and appropriately setting the transfer conditions at the time of each pattern transfer. It can be easily realized. For this reason, even when patterns having different functions (usually different transfer conditions) are arranged in the same layer, any pattern in the layer can be exposed under suitable or optimum exposure conditions.
[0184]
Further, by double exposure, it is possible to simultaneously increase the depth of focus and improve the resolution.
[0185]
As described above, finally, it is possible to improve device productivity by improving throughput and yield.
[0186]
In the second embodiment, the case of performing double exposure on a plurality of shot areas formed in a matrix arrangement on the wafer W has been described. However, the present invention is not limited to this, and is arranged in a row in the scanning direction. The present invention can also be suitably applied when double exposure is performed on a plurality of shot regions arranged. That is, in such a case, in the first exposure process, a mask stage (corresponding to reticle stage RST) on which the first mask and the second mask are placed and an object stage on which an object such as a wafer is placed ( The wafer stage WST) is moved synchronously in a predetermined scanning direction, and the transfer condition is changed according to the changed pattern during switching of the transfer target pattern (mask) during the synchronous movement. The pattern of the first mask and the pattern of the second mask are successively transferred by the scanning exposure method to each of the two regions arranged in the scanning direction. That is, it is possible to perform continuous scanning exposure of patterns with different transfer conditions for two regions, which has been difficult in the past, and at least the mask stage and the object stage between the regions compared to the case where scanning exposure is performed for each region. The acceleration and deceleration time can be reduced, and the throughput can be improved accordingly.
[0187]
In the second exposure process, the first mask pattern and the second mask pattern are transferred onto the object in the same manner as described above, and the first pattern and the second mask pattern are transferred in the first exposure process. A pattern different from the pattern transferred in the first exposure process is transferred onto at least one of the two areas to which the two patterns are transferred. Therefore, also in the second exposure process, the acceleration and deceleration times of the mask stage and the object stage at least between the regions can be reduced as described above, and the throughput can be improved correspondingly.
[0188]
Also in this case, when looking at the area where the pattern of the first mask and the pattern of the second mask are transferred, the overlay exposure of the patterns with different transfer conditions can appropriately set the transfer conditions at the time of each pattern transfer. This is easily realized with the set double exposure.
[0189]
In the second embodiment, a reticle on which the same pattern is formed can be used as the reticle Rc and the reticle Rd. In such a case, the same effects as those of the second embodiment described above can be obtained, and the transfer conditions need not be switched when the transfer pattern (reticle) is switched. Similarly, two reticles on which the same pattern is formed may also be used in the case of double exposure for a plurality of shot regions arranged in a line in the scanning direction or normal exposure. Even in such a case, at least the mask stage and the object stage between the regions can be accelerated and the deceleration time can be reduced.
[0190]
Also in the second embodiment, instead of the illumination system aperture stop plate 4 described above, an illumination system aperture stop composed of an iris diaphragm similar to the pupil aperture stop 24 described above may be used. In this case, the main controller 20 determines the size of the aperture of the illumination system aperture stop in parallel with the change of the pupil aperture stop 24 during the scanning exposure, that is, the N.I. A. (Illumination NA) can be changed.
[0191]
In the second embodiment, the case of double exposure on the same wafer has been described. However, a method of changing the pattern transfer condition during the synchronous movement of both stages RST and WST according to the preferred transfer condition of the pattern. It is not particularly necessary to explain that the method can be applied as it is to multiple exposures more than triple exposure. In this case as well, the main control device constituting the transfer condition changing device may change the transfer condition based on the position information of the reticle stage in accordance with the pattern formation state on the reticle.
[0192]
In each of the embodiments described above, the pattern transfer conditions (NA of the projection optical system, etc.) are changed according to the position of the reticle (reticle stage) in the scanning direction. As well as the speed obtained by differentiating the position of the reticle (reticle stage) in the scanning direction, the position of the wafer stage (wafer) that moves synchronously with the reticle stage, or the speed of the reticle can be calculated by a predetermined calculation. The pattern transfer conditions may be changed based on any information.
[0193]
In each of the above embodiments, the present invention uses ArF excimer laser light (wavelength 193 nm) or F as the exposure light IL.₂Although the case where the present invention is applied to an exposure apparatus using laser light (wavelength 157 nm) has been described, the present invention is not limited thereto, and Kr having a wavelength of 146 nm₂Laser light, Ar with a wavelength of 126 nm₂The present invention can also be suitably applied to an exposure apparatus that uses vacuum ultraviolet light such as laser light, or an EUV exposure apparatus that uses EUV light in the soft X-ray region with a wavelength of 5 to 30 nm.
[0194]
In addition, in the present invention, a fiber in which, for example, erbium (or both erbium and ytterbium) is doped with an infrared or visible single wavelength laser beam oscillated from a DFB semiconductor laser or fiber laser as an energy beam. Harmonics that are amplified by an amplifier and wavelength-converted to ultraviolet light using a nonlinear optical crystal may be used. In this case, for example, an ytterbium-doped fiber laser can be used as the single wavelength oscillation laser.
[0195]
The projection optical system and the illumination optical system shown in the above embodiments are merely examples, and the present invention is of course not limited to this. For example, the projection optical system is not limited to a refractive optical system, and a reflective system composed only of reflective optical elements, or a catadioptric system having a reflective optical element and a refractive optical element (catadioptric system) may be employed.
[0196]
Furthermore, the present invention is not only an exposure apparatus used for manufacturing semiconductor elements, but also an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern onto a rectangular glass plate, a display apparatus such as a plasma display or an organic EL, The present invention can be widely applied to an exposure apparatus for manufacturing a thin film magnetic head, an image sensor (CCD, etc.), a micromachine, a DNA chip, and the like, and an exposure apparatus used for manufacturing a mask or a reticle. 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., glass substrates or silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern.
[0197]
The illumination optical system and projection optical system PL composed of a plurality of lenses are incorporated in the exposure apparatus body for optical adjustment, and a reticle stage RST, wafer stage WST, and the like made up of a large number of mechanical parts are incorporated in the exposure apparatus body. The exposure apparatus according to the present invention, such as the exposure apparatus of the above-described embodiment, can be manufactured by connecting wirings and pipes and performing overall adjustment (electrical adjustment, operation check, etc.). The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.
[0198]
<Device manufacturing method>
Next, an embodiment of a device manufacturing method using the exposure apparatus and the exposure method of each embodiment described above in a lithography process will be described.
[0199]
FIG. 9 shows a flowchart of a manufacturing example of a device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.). As shown in FIG. 9, first, in step 201 (design step), device function / performance design (for example, circuit design of a semiconductor device) is performed, and pattern design for realizing the function is performed. Subsequently, in step 202 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 203 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.
[0200]
Next, in step 204 (wafer processing step), using the mask and wafer prepared in steps 201 to 203, an actual circuit or the like is formed on the wafer by lithography or the like as will be described later. Next, in step 205 (device assembly step), device assembly is performed using the wafer processed in step 204. Step 205 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as necessary.
[0201]
Finally, in step 206 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step 205 are performed. After these steps, the device is completed and shipped.
[0202]
FIG. 10 shows a detailed flow example of step 204 in the case of a semiconductor device. In FIG. 10, in step 211 (oxidation step), the surface of the wafer is oxidized. In step 212 (CVD step), an insulating film is formed on the wafer surface. In step 213 (electrode formation step), an electrode is formed on the wafer by vapor deposition. In step 214 (ion implantation step), ions are implanted into the wafer. Each of the above-described steps 211 to 214 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.
[0203]
In each stage of the wafer process, when the above-described pretreatment process is completed, the posttreatment process is executed as follows. In this post-processing process, first, in step 215 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step 216 (exposure step), the circuit pattern of the mask is transferred to the wafer by the lithography system (exposure apparatus) described above. Next, in step 217 (development step), the exposed wafer is developed, and in step 218 (etching step), the exposed member other than the portion where the resist remains is removed by etching. In step 219 (resist removal step), the resist that has become unnecessary after the etching is removed.
[0204]
By repeatedly performing these pre-processing steps and post-processing steps, multiple circuit patterns are formed on the wafer.
[0205]
According to the device manufacturing method of the present embodiment described above, since exposure is performed using the exposure apparatus and the exposure method of each of the embodiments in the exposure step (step 216), exposure accuracy corresponding to the pattern is sufficiently maintained. However, exposure is performed. Therefore, at least the yield of micro devices having a fine pattern can be improved, and the productivity can be improved.
[0206]
【The invention's effect】
As described above, according to the exposure method of the present invention, there is an effect that it is possible to realize at least one of an improvement in pattern design freedom for each layer and an improvement in device productivity.
[0207]
In addition, the exposure apparatus according to the present invention has an effect that it is possible to realize at least one of improvement in the degree of freedom in pattern design for each layer and improvement in device productivity.
[0208]
In addition, according to the device manufacturing method of the present invention, there is an effect that it is possible to surely improve the productivity of the microdevice.
[Brief description of the drawings]
FIG. 1 is a view showing the schematic arrangement of an exposure apparatus according to a first embodiment of the present invention.
FIG. 2 is a plan view showing a reticle used in the first embodiment.
FIG. 3A is a diagram showing a change in the speed of the reticle stage during exposure in the first embodiment, with the horizontal axis as a position in the scanning direction, and FIG. 3B is a diagram in FIG. It is a figure which shows the change of the energy amount in the image surface corresponding to A).
FIG. 4 is a plan view showing a reticle according to a modified example.
5A is a diagram showing a change in the speed of the reticle stage during exposure using the reticle shown in FIG. 4, with the horizontal axis as a position in the scanning direction, and FIG. 5B is a diagram showing FIG. It is a figure which shows the change of the energy amount in the image surface corresponding to (A).
FIG. 6 is a plan view showing a reticle stage according to a second embodiment of the present invention.
7A is a diagram showing an example of an image of a pattern formed on a wafer after completion of the first exposure when double exposure is performed in the second embodiment; FIG. B) is a diagram illustrating an example of an image of a pattern formed on the wafer after the second exposure is completed.
FIGS. 8A and 8B are diagrams for explaining the effect of the second embodiment of the present invention. FIG.
FIG. 9 is a flowchart for explaining an embodiment of a device manufacturing method according to the present invention.
10 is a flowchart showing an example of specific processing in step 204 in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Light source (a part of 3rd change apparatus, a part of transfer condition change apparatus), 4 ... Illumination system aperture stop plate (a part of 2nd change apparatus, a part of transfer condition change apparatus), 11 ... Reticle driving unit (part of driving device), 19 ... stage control system (part of driving device), 20 ... (part of first changing device, part of second changing device, third changing device) , 21... Wafer drive part (part of the drive device), 24... Pupil aperture stop (part of the first change device, part of the transfer condition change device), 40: Drive system (part of the second change device, part of the transfer condition change device), 100: exposure device, R: reticle (mask), W: wafer (object), PL: projection optical system, IL ... Exposure light (energy beam).

Claims (15)

An exposure apparatus that synchronously moves a mask and an object and transfers a pattern formed on the mask onto the object via a projection optical system,
An illumination optical system for illuminating the mask with an energy beam;
A driving device for synchronously moving the mask and the object;
While the mask is illuminated by the energy beam from the illumination optical system and the mask and the object are synchronously moved by the driving device, the pattern transfer condition according to the positional information of the mask is set to the first. A transfer condition changing device for changing the condition to the second condition;
While controlling the driving device and changing the pattern transfer condition from the first condition to the second condition by the transfer condition changing device, the speed of the synchronous movement of the mask and the object is changed to the first condition. an exposure device provided with; controller and to change a different rate than the synchronous movement speed between the speed and the mask and the object corresponding to the second condition of the synchronous mobile between the mask and the object corresponding to.   The exposure apparatus according to claim 1, wherein the transfer condition changing device includes a first changing device that changes a numerical aperture of the projection optical system.   3. The exposure apparatus according to claim 2, wherein the transfer condition changing device further includes a second changing device that changes a light amount distribution on either the pupil plane of the illumination optical system or the conjugate plane. 4.   The transfer condition changing device further includes a third changing device that changes an energy amount of the energy beam irradiated on the object in accordance with a change in a speed of synchronous movement between the mask and the object by the control device. The exposure apparatus according to claim 2, wherein the exposure apparatus is provided.   The exposure apparatus according to claim 1, wherein the transfer condition changing device changes the transfer condition according to a pattern formation state on the mask.   The exposure apparatus according to claim 1, wherein the transfer condition changing operation sequence by the transfer condition changing apparatus can be set from the outside. An exposure method for transferring a pattern formed on a mask onto an object via a projection optical system,
The mask and the object are moved synchronously while the mask is illuminated with an energy beam, and the pattern transfer condition is changed from the first condition to the second condition according to the positional information of the mask during the synchronous movement. A transfer condition changing step;
While changing the pattern transfer condition from the first condition to the second condition according to the position information of the mask, the speed of the synchronous movement of the mask and the object is changed to the mask corresponding to the first condition. And a speed changing step for changing to a speed different from the speed of the synchronous movement between the mask and the object corresponding to the second condition .   The exposure method according to claim 7, wherein the change of the transfer condition includes a change of a numerical aperture of the projection optical system.   9. The exposure method according to claim 8, wherein the change of the transfer condition further includes a change of a light amount distribution on either a pupil plane of an illumination optical system that illuminates the mask with the energy beam or a conjugate plane thereof. .   The change of the transfer condition further includes changing an energy amount of the energy beam irradiated on the object according to a change of a speed of synchronous movement between the mask and the object. The exposure method according to 8 or 9.   The exposure method according to any one of claims 7 to 10, wherein in the transfer condition changing step, the transfer condition is changed according to a pattern formation state on the mask. An exposure method in which a plurality of different patterns are superimposed and transferred onto a predetermined area on an object via a projection optical system,
The first mask so that the first mask on which the first pattern is formed, the second mask on which the second pattern different from the first pattern is formed, and the object are scanned relative to the energy beam. And while the mask stage on which the second mask is placed and the object are moved synchronously in a predetermined scanning direction, a transfer target pattern to be transferred onto the object during the synchronous movement is transferred from the first pattern to the second pattern. When switching to the pattern, the transfer condition is changed from the first condition for transferring the first pattern to the second condition for transferring the second pattern, and the transfer condition is changed from the first condition to the second condition. during the change in conditions, the synchronous movement of said synchronizing a moving speed of said mask and the object corresponding to the speed and the second condition of the synchronous mobile between the mask and the object corresponding to the first condition The speed is changed to different speeds, a first exposure step of transferring to each of the first pattern and the two regions arranged a second pattern in the scanning direction on the object via the projection optical system;
A pattern different from the pattern transferred in the first exposure step is transferred onto at least one of the two regions to which the first pattern and the second pattern are transferred in the first exposure step. An exposure method comprising: an exposure step;   In the second exposure step, the mask stage and the object are synchronously moved in a predetermined scanning direction so that the first and second masks and the object are scanned relative to an energy beam. 13. The exposure method according to claim 12, wherein the transfer condition is changed according to the pattern after the switching during the switching of the transfer target pattern during the synchronous movement. In the first exposure step, a step of transferring the first and second patterns to the object and a step of moving the object are alternately repeated to form a set of two or more sets of regions on the object. In contrast, the first pattern and the second pattern are transferred,
In the second exposure step, the step of transferring the first and second patterns to the object and the step of moving the object are alternately repeated, and the first pattern and the second pattern are transferred in the first exposure step. The pattern different from the pattern transferred in the first exposure step is transferred to at least one area of each set of areas to which the pattern is transferred. Exposure method. A device manufacturing method including a lithography process,
In the said lithography process, the exposure method as described in any one of Claims 7-14 is used, The device manufacturing method characterized by the above-mentioned.

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