JP2000235945A - Scanning type aligner and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve uniformity of line widths in each shot region on a substrate by controlling the light quantity of exposed lights with which the substrate is irradiated. SOLUTION: During a scanning exposure to one section region on a substrate W, integrated exposure in the scanning direction on the substrate W is controlled so as to be changed according to exposure correction data for correcting the nonuniformity of the pattern line width in the scanning direction in the section region stored in a memory 51 by a controller 50, based on the change of the integrated exposure calculated by an energy controller in a laser 16 based on the detected result of a sensor 46 and the position of the substrate W measured by an interferometer 54W in this system 10. Thus, the uniformity of the line width in the scanning direction of a pattern transfer image transferred to each section area can be improved as a result of the scanning exposure to each section region on the substrate W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning exposure apparatus and a scanning exposure method, and more particularly, to a method for manufacturing, for example, a semiconductor device, a liquid crystal display device, an imaging device (such as a CCD) or a thin film magnetic head. The present invention relates to a scanning exposure apparatus and a scanning exposure method using a pulse light source used in a lithography process.

[0002]

2. Description of the Related Art Conventionally, for example, when a semiconductor device is manufactured, a wafer on which a resist (photosensitive material) is applied via a projection optical system to a pattern of a mask or a reticle (hereinafter, collectively referred to as "reticle" as appropriate). Alternatively, a projection exposure apparatus that transfers the image onto each shot area on a substrate such as a glass plate is used. As such a projection exposure apparatus, a step-and-repeat type reduction projection exposure apparatus (so-called stepper) has been used.
As semiconductor elements become more highly integrated and device rules (minimum line width) become finer, a step-and-scan type scanning exposure apparatus (so-called scanning stepper) capable of performing high-precision exposure in a larger area than a stepper. ) Is becoming mainstream.

One basic function of the projection exposure apparatus is an exposure amount control function for keeping the integrated exposure amount (integrated exposure energy) for each point in each shot area of a wafer within an appropriate range. In a projection exposure apparatus of a static exposure type such as a stepper, a continuous light source such as an ultra-high pressure mercury lamp or a pulse laser light source such as an excimer laser light source is used as an exposure light source. Basically, cut-off control was adopted. In this cut-off control, during the exposure light exposure on a wafer coated with a photosensitive material (resist), a part of the exposure light is branched and guided to a photoelectric detector called an integrator sensor, and the signal is transmitted through the integrator sensor. The exposure amount on the wafer is indirectly detected, and the integrated value of the detection result is a predetermined level (critical exposure amount) corresponding to the integrated exposure amount (hereinafter, referred to as “set exposure amount”) required for the photosensitive material. (In the case of continuous light, the shutter starts to be closed when the critical level is exceeded).

However, in a scanning exposure type apparatus such as a scanning stepper, the above-described cutoff control cannot be applied because the exposure amount control focusing on only one point on the wafer cannot be applied. Therefore, conventionally, as a first control method,
A method of simply controlling the exposure amount by integrating the light amounts of the respective pulse illumination lights (open exposure amount control system) has been used.
In addition, as a second control method, for example,
No. 2022, a slit-shaped exposure area on a wafer in the scanning direction (an area conjugate to a slit-shaped illumination area on a reticle, and the wafer is relatively scanned with respect to this area. ) Is measured in real time for each pulse illumination light for the area included in the pulse illumination light, the target energy of the next pulse illumination light is individually calculated based on the integrated exposure light, and the energy of each pulse illumination light is calculated. A control method (an exposure control method for each pulse) is also used.

FIG. 10A schematically shows a state in which a pattern of a reticle R is transferred and exposed to a shot area SA on a wafer W as a substrate by using the above-described scanning stepper. As shown in FIG. 10A, in this scanning stepper, a slit-shaped illumination area IRA on the reticle R is illuminated by exposure light IL from an illumination optical system (not shown), and a portion in the illumination area IRA. Is projected onto a wafer W having a surface coated with a resist via a projection optical system PL, and a reduced image of the pattern in the illumination area IRA is formed on an exposure area IA conjugate to the illumination area IRA on the wafer W. (Partial inverted image) is transferred. In this case, since the reticle R and the wafer W are in an inverted image forming relationship, the reticle stage RST holding the reticle R and the wafer stage WST holding the wafer W are scanned in the scanning direction ( FIG. 10 (A)
(The left and right directions on the drawing) at the speed ratio according to the projection magnification of the projection optical system PL. Thereby, the pattern area P of the reticle R
The entire surface of A is accurately transferred to the shot area SA on the wafer W.

[0006] During the scanning exposure of each shot area on the wafer W, the above-described exposure control is performed by a control device (not shown) to thereby provide uniformity of illuminance in the shot area SA and to improve the uniformity between the shot areas. The aim was to ensure uniformity of line width control accuracy.

[0007]

By the way, in an optical system such as an illumination optical system or a projection optical system of a projection exposure apparatus such as a stepper or a scanning stepper, internal scattering of glass materials and the like, surface processing and coating are not performed. Scattering due to unevenness or inhomogeneity of light, scattering of leaked light on the surface of the member holding the optical member, and the like occur. The scattered light (also referred to as “flare”) generated by such scattering is a component that is originally unnecessary for imaging, but the optical system has a characteristic of incorporating such unnecessary component. Such scattered light becomes a light component that is superimposed on the light flux of the exposure light that contributes to the image formation, causes the contrast of the image of the pattern to be reduced, and causes exposure with fog of the scattered light (hereinafter, referred to as “fogging exposure”).
Therefore, in the case of a positive photosensitive material, the phenomenon is observed as a line width thinning phenomenon of a pattern image.

FIG. 10B is a plan view showing that scattered light leaks out of the shot area SA when the entire pattern area PA on the reticle R is projected onto the shot area SA on the wafer W. This is shown visually in the figure. In this case, as shown in FIG. 10C, the intensity of the scattered light component that has permeated out of the shot area is about 1% of the intensity of the illumination light beam applied to the shot area shown in FIG. It is said that the length of the seepage outside the shot region (width of the seepage portion) is about several mm in the case of an optical system for a recent semiconductor exposure apparatus having a field size of about 20 to 30 mm. . In this case, naturally, the scattered light is also fogged (superimposed) inside the shot area on the wafer W. As a result, the following phenomenon occurs.

That is, since the distance between the shot areas on the wafer (street line width) exposed by a stepper or a scanning stepper usually used in the exposure of a semiconductor chip is about several tens to hundreds of μm, scattering occurs. The length of the light that leaks out of the shot is much larger than the distance between the shot areas on the wafer. For this reason, the vicinity of a shot adjacent to each shot area is affected by fogging exposure of scattered light generated at the time of exposure of the adjacent shot area, but the line of the pattern in the shot area obtained as an actual exposure result Considering the width uniformity, it is considered that the light intensity distribution is substantially uniform in each shot region located inside on the wafer as a result of the influence of the fogging exposure of the scattered light.

However, an edge shot located at a peripheral portion on the wafer (in the present specification, an “edge shot” is a shot region in the peripheral portion of the wafer W and is at least one side in the scanning direction, or non-scanning. Means a shot area where there is no adjacent shot on at least one side of the direction).
In the vicinity of the side, there is no fogging exposure of scattered light generated at the time of exposure of the adjacent shot area, so a line width thinning phenomenon occurs near the other side affected by the fogging exposure of scattered light. However, as a result, in the edge shot, a line width change (line width non-uniformity) occurs in the shot region unlike other shot regions located inside the wafer.

Since the line width variation in the edge shot becomes large due to the above line width change, in order to suppress the variation, the shot area (for the exposure amount correction not intended to take a chip further outside the edge shot) is used. There is a method of exposing a “dummy shot”. However, since the exposure of the dummy shot is for exposure of a shot that does not originally contribute to chip production,
This causes a decrease in throughput.

In addition, the line width non-uniformity of each shot area on the wafer in the scanning exposure apparatus can be caused by various factors other than the scattered light.

The present invention has been made under such circumstances, and provides a scanning exposure apparatus and a scanning exposure method that can improve line width uniformity in each shot area (partition area) on a substrate. It is in.

[0014]

According to the first aspect of the present invention, a mask (R) and a substrate (W) are applied to an illumination area illuminated by pulse illumination light (IL) from a pulse light source (16).
A scanning type exposure apparatus that synchronously moves a pattern formed on the mask onto a substrate via a projection optical system (PL) by synchronously moving the pattern on a substrate through a predetermined scanning direction, wherein the pulse is applied during scanning exposure. An energy detector (46) for sequentially detecting the amount of energy of each of the illumination light; and a predetermined N pulses (N is 2 or more) successively shifted by a unit pulse number using the detection result of the energy detector. An arithmetic unit (16d) for calculating an integrated light quantity of (integer), and exposure amount correction data for correcting non-uniformity of the pattern line width in the scanning direction measured in advance for each of the plurality of divided areas on the substrate. A storage device (51); a position detector (54W) for measuring a position of the substrate; and a mask pattern that is sequentially transferred onto one of the divided regions on the substrate by a scanning exposure method. Based on a series of changes in the integrated light amount calculated by the arithmetic unit and the position data of the substrate detected by the position detector, a scanning direction on the substrate is changed in accordance with the exposure amount correction data. And a control device (50) for controlling the amount of exposure.

According to this, during the scanning exposure of one of the plurality of partitioned areas on the substrate, the energy amount of each of the pulsed illumination light is sequentially detected by the energy detector, and the arithmetic unit detects the energy amount of the energy detector. Using the detection results,
The integrated light amount of N pulses (N is an integer of 2 or more and is the number of irradiation pulses of pulse illumination light for each point on the substrate which is predetermined according to the set exposure amount) sequentially shifted by the unit pulse number. Is calculated. That is, a series of changes in the integrated light amount are calculated by the arithmetic unit, and thereby the integrated exposure amount at each point on the substrate is obtained. However, strictly speaking, depending on the shape of the intensity distribution of the illumination light on the substrate and the like, for example, there is a slight difference between the integrated value of the amount of light detected by the energy detector and the actual integrated exposure energy on the substrate. Although there may be an error, the integrated value can be approximately regarded as the actual integrated exposure energy. The position of the substrate during the scanning exposure is detected in real time by the position detector.

[0016] Then, the controller 1
While the pattern of the mask is sequentially transferred onto one of the divided areas by the scanning exposure method, based on the above series of changes in the integrated light amount calculated by the arithmetic unit and the position data of the substrate detected by the position detector. The exposure correction data corresponding to the divided area in the exposure correction data for correcting the non-uniformity of the pattern line width in the scanning direction measured in advance for each of the plurality of divided areas on the substrate stored in the storage device Is controlled in such a manner that the exposure amount in the scanning direction on the substrate changes.

Therefore, according to the present invention, as a result of the scanning exposure on each of the divided areas on the substrate, the line width uniformity in the scanning direction of the pattern transfer image transferred to each of the divided areas is improved.

In this case, various causes of the non-uniformity of the pattern line width in the divided area are considered, and the exposure correction data may be for all or any combination of these factors. As in the invention described in Item 2, it is preferable that the exposure amount correction data is data for correcting non-uniformity of the pattern line width due to the influence of flare. In such a case, it is possible to correct the pattern line width non-uniformity of at least the influence of flare in each of the divided areas on the substrate.

In the first or second aspect of the present invention, various methods of controlling the exposure amount by the control device are conceivable.
For example, as in the invention described in claim 3, the control device (5
0) The exposure amount may be controlled by finely adjusting the pulse energy of each pulse illumination light (IL) from the pulse light source (16).

In each of the first to third aspects of the present invention, as in the fourth aspect of the present invention, the control device may be arranged such that each point on the substrate scans an illumination area by the pulse illumination light in a scanning direction. The amount of exposure may be adjusted by adjusting the number of irradiation pulses applied to each point during the crossing. For example, the exposure amount adjustment may be realized by changing the scanning speed between the mask and the substrate.

In the scanning exposure apparatus according to the second aspect, as in the invention according to the fifth aspect, the exposure amount correction data includes, in accordance with the presence or absence of an adjacent area in the scanning direction of the divided area, It is desirable that at least three types of data are included. In such a case, if the sectioned area to be exposed is a sectioned area in which both adjacent areas in the scanning direction are present, or if it is a sectioned area present in one of the sections, any of the sectioned areas in which no adjacent area in the scanning direction exists does not exist. Even in this case, it is possible to improve the uniformity of the pattern line width due to the influence of flare in the scanning direction, and it becomes unnecessary to expose the above-described dummy shot to the adjacent area in the scanning direction.

In the scanning exposure apparatus according to the first aspect, the mask pattern which is the basis of the exposure amount correction data may be a dense pattern (for example, a line and space pattern). Like the invention of
The exposure amount correction data is obtained based on a measurement result of a line width distribution of a transfer image of an isolated pattern among transfer images obtained by transferring the pattern of the mask onto a plurality of divided areas on the substrate in advance. It is desirable that the data is data for equalizing the pattern line width of each of the divided areas. Isolated pattern (eg, isolated line, contact hole pattern)
Is more sensitive to the exposure dose than the dense pattern, so the pattern line width of each of the plurality of divided areas obtained based on the measurement result of the line width distribution of the transferred image of the isolated pattern is made uniform. By using the data to be performed as the exposure correction data, more accurate exposure control can be realized, and the pattern line width uniformity can be further improved.

In the scanning exposure apparatus according to each of the first and second aspects of the present invention, as in the seventh aspect of the present invention, the exposure amount correction data is obtained for each of a plurality of divided areas on the substrate. The data may be data for making the pattern line width uniform so that another portion is matched with the line width at the center in the scanning direction in the divided area measured in advance. In such a case, in any of the divided regions on the substrate, the line width at the central portion in the scanning direction is uniformly affected by the flare during exposure, but the autofocus / autoleveling control accuracy during scanning exposure, Since pattern line width errors due to other factors are unlikely to occur, using data for making the pattern line width uniform so that other portions match the line width of such a portion as exposure amount correction data enables the In addition to improving the line width uniformity in the scanning direction for each of the divided areas, the uniformity of the pattern line width between the divided areas can also be improved.

In the scanning exposure apparatus according to any one of the first to seventh aspects, as in the eighth aspect of the invention, the energy detector (46) is provided with the pulsed light source (16). It is desirable that the mask (R) is arranged inside an illumination optical system that illuminates the mask (R) with pulse illumination light (IL). Normally, in an exposure apparatus using a pulse light source, an optical axis shift generated between the pulse light source and the exposure apparatus main body when the substrate is moved to change the exposure position on the substrate causes a difference between the pulse light source and the energy detector. Energy transmission efficiency fluctuates, the transmittance of the optical member in the illumination optical system generated between the shot areas on the substrate, and between the shot areas, or the reflectance may fluctuate, but in the present invention, Since the energy detector is disposed inside the illumination optical system that illuminates the mask with the pulse illumination light from the pulse light source, each of the above-described fluctuations mainly occurs at a stage preceding the energy detector (on the pulse light source side). Since it hardly occurs in the subsequent stages, the accuracy of exposure amount control on the substrate does not decrease due to each of the above fluctuations. That is, during scanning exposure, the energy detector sequentially detects the respective energy amounts of the pulsed illumination light including such fluctuations, and controls the exposure amount for the substrate based on the detection result of the energy detector. Therefore, it is possible to control the exposure amount with high accuracy without being affected by the above-described various fluctuations.

According to a ninth aspect of the present invention, the mask (R) and the substrate (W) are synchronously moved along a predetermined scanning direction with respect to the illumination area illuminated by the pulse illumination light (IL). In a scanning exposure method for transferring a pattern formed on a mask onto the substrate via a projection optical system (PL), the pattern of the mask is sequentially transferred onto an arbitrary partitioned area on the substrate by a scanning exposure method. In the meantime, the respective energy amounts of the pulsed illumination light are sequentially detected, and based on the detected energy amounts, the number of unit pulses is shifted, and a predetermined N pulses (N is an integer of 2 or more) are successively obtained. ) Is calculated, and changes in accordance with exposure amount correction data for correcting non-uniformity of the pattern line width of the divided area based on the calculated change in the integrated amount of light and the position of the substrate. Yo Characterized in that said controlling the exposure amount in the scanning direction on the substrate.

According to this, while the mask pattern is sequentially transferred onto an arbitrary partitioned area on the substrate by the scanning exposure method, the respective energy amounts of the pulsed illumination light are sequentially detected, and the detected energy amounts are detected. On the basis of the amount, the integrated light amount for the predetermined N pulses (N is an integer of 2 or more) is sequentially calculated by shifting the unit pulse number by one unit, and a series of changes in the integrated light amount is calculated. Then, based on the calculated change in the integrated light amount and the position of the substrate, the substrate is changed so as to change in accordance with exposure amount correction data for correcting the non-uniformity of the pattern line width of the divided area on the substrate. Is controlled in the scanning direction. Therefore, according to the present invention, as a result of scanning exposure on an arbitrary partitioned area on the substrate,
The uniformity of the line width in the scanning direction of the pattern transfer image transferred to the defined area is improved.

In this case, the exposure amount correction data is not particularly limited as long as the data can correct the non-uniformity of the pattern line width of the divided area. Prior to the scanning exposure, the line width distribution of the transferred image of the pattern of the mask transferred to each of the plurality of divided areas on the substrate is measured, based on the measurement result of the line width distribution. The exposure amount correction amount data of each of the plurality of divided regions may be obtained. In such a case, based on the actual resist process, the actual illumination conditions, and the measurement results of the line width distribution of the transferred image of the pattern of the mask obtained as a result of the actual exposure using the mask used for the actual exposure. Since the exposure correction amount data for each of the plurality of divided areas is determined,
As a result, by controlling the exposure amount in the scanning direction on the substrate so as to change in accordance with the exposure amount correction data, it is possible to maximize the uniformity of the pattern line width in the scanning direction of each partitioned area. is there.

In this case, as in the invention according to claim 11, the exposure correction data of the divided area having no divided area adjacent to at least one of the scanning directions on the substrate is provided.
The measurement may be performed using a measurement result of the line width distribution in the scanning direction of the divided area and a measurement result of the line width distribution of the divided area having the adjacent divided areas on both sides in the scanning direction.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG.

FIG. 1 shows a scanning exposure apparatus 1 according to one embodiment.
0 is shown. This scanning exposure apparatus 10
Is a step-and-scan type scanning exposure apparatus using an excimer laser light source as a pulse light source as an exposure light source.

The scanning exposure apparatus 10 includes an illumination system 12 including an excimer laser light source 16 and a reticle stage as a mask stage for holding a reticle R as a mask illuminated by exposure illumination light IL from the illumination system 12. RST, exposure illumination light IL emitted from reticle R
A projection optical system PL that projects the light onto a wafer W as a substrate,
An XY stage 14 on which a Z tilt stage 58 as a substrate stage for holding the wafer W is mounted, and a control system for these components.

The illumination system 12 includes the excimer laser light source 1
6, beam shaping optical system 18, energy rough adjuster 20, fly-eye lens 22, illumination system aperture stop plate 24, beam splitter 26, first relay lens 28A, second relay lens 28B, fixed reticle blind 30A, movable reticle blind 30B, a mirror M for bending the optical path, a condenser lens 32, and the like.

Here, the components of the illumination system 12 will be described. As the excimer laser light source 16, K
rF excimer laser light source (oscillation wavelength 248 nm), Ar
An F excimer laser light source (oscillation wavelength 193 nm) or an F ₂ excimer laser light source (oscillation wavelength 157 nm) is used. Instead of the excimer laser light source 16, a pulse light source such as a metal vapor laser light source or a harmonic generator of a YAG laser may be used as the exposure light source.

FIG. 2 shows the inside of the excimer laser light source 16 together with the main controller 50. The excimer laser light source 16 includes a laser resonator 16a, a beam splitter 16b, an energy monitor 16c, an energy controller 16d as an arithmetic unit, a high-voltage power supply 16e, and the like.

The laser beam LB emitted in a pulse form from the laser resonator 16a enters a beam splitter 16b having a high transmittance and a small reflectance, and the laser beam LB transmitted through the beam splitter 16b is emitted to the outside. You. Further, the laser beam LB reflected by the beam splitter 16b is used as an energy monitor 1 comprising a photoelectric conversion element.
6c, the photoelectric conversion signal from the energy monitor 16c is supplied to the energy controller 16d as an output ES via a peak hold circuit (not shown).

At the time of normal light emission, the energy controller 16d sets the output ES of the energy monitor 16c to a value corresponding to the target value of energy per pulse in the control information TS supplied from the main controller 50. The power supply voltage of the high-voltage power supply 16e is feedback-controlled. The unit of the control amount of energy corresponding to the output ES of the energy monitor 16c is [mJ / pulse]. The energy controller 16d sets the power supply voltage in the high-voltage power supply 16e based on the control information TS from the main control device 50, as described later, whereby the pulse energy of the laser beam LB emitted from the laser resonator 16a is reduced. It is set near a predetermined value.

In this case, the average value of the energy per pulse of the excimer laser light source 16 is normally stabilized at a predetermined center energy E ₀ , but the average value of the energy is lower and higher than the center energy E ₀ . It is configured so that it can be controlled within a predetermined variable range (for example, about ± 10%). In the present embodiment, fine modulation of pulse energy is performed in the variable range. Further, a shutter 16f for shielding the laser beam LB in accordance with control information from the main controller 50 is also provided outside the beam splitter 16b in the excimer laser light source 16.

Returning to FIG. 1, the beam shaping optical system 18
Is for shaping the cross-sectional shape of the laser beam LB pulsed from the excimer laser light source 16 so that the laser beam LB efficiently enters a fly-eye lens 22 provided behind the optical path of the laser beam LB. It is composed of a beam expander (both not shown) and the like.

The energy rough adjuster 20 is disposed on the optical path of the laser beam LB behind the beam shaping optical system 18.
Here, the transmittance around the rotating plate 34 (= 1−the extinction ratio)
(For example, two ND filters 36A and 36D are shown in FIG. 1), and its rotating plate 34 is rotated by a driving motor 38 The transmittance of the incident laser beam LB can be switched from 100% in geometric progression in a plurality of steps. Drive motor 38
Is controlled by the main controller 50. Note that a rotary plate similar to the rotary plate 34 may be arranged in two stages so that the transmittance can be more finely adjusted by a combination of two sets of ND filters.

The fly-eye lens 22 is arranged on the optical path of the laser beam LB emitted from the energy rough adjuster 20, and forms a number of secondary light sources for illuminating the reticle R with a uniform illuminance distribution. Hereinafter, the laser beam emitted from the secondary light source is referred to as “pulse illumination light IL”.

In the vicinity of the exit surface of the fly-eye lens 22,
An illumination system aperture stop plate 24 made of a disk-shaped member is arranged. This illumination system aperture stop plate 24 is provided at equal angular intervals,
For example, an aperture stop composed of a normal circular aperture, an aperture stop composed of small circular apertures for reducing the σ value that is a coherence factor, a ring-shaped aperture stop for annular illumination, and a plurality of apertures for a modified light source method. A modified aperture stop which is eccentrically arranged (only two types of aperture stops are shown in FIG. 1) and the like are arranged. The illumination system aperture stop plate 24 is configured to be rotated by a driving device 40 such as a motor controlled by a main controller 50, so that any one of the aperture stops is driven by the pulse illumination light IL.
Are selectively set on the optical path of.

A beam splitter 26 having a small reflectance and a large transmittance is arranged on the optical path of the pulse illumination light IL emitted from the illumination system aperture stop plate 24. Further, on the optical path behind this, a fixed reticle blind 30A and a movable reticle blind 30A are provided. A relay optical system including a first relay lens 28A and a second relay lens 28B is arranged with a reticle blind 30B interposed therebetween.

The fixed reticle blind 30A is disposed on a plane slightly defocused from a plane conjugate to the pattern plane of the reticle R, and has a rectangular opening defining an illumination area 42R on the reticle R. In addition, a movable reticle blind 30B having an opening whose position and width in the scanning direction are variable near the fixed reticle blind 30A.
Is arranged. This movable reticle blind 30B
The plurality of movable blades defining the opening are controlled by the main controller 50 via a drive system (not shown) at the start and end of the scanning exposure, so that the illumination area 42 </ b> R is further restricted. Exposure of a portion is prevented.

On the optical path of the pulse illumination light IL behind the second relay lens 28B constituting the relay optical system, the second
A folding mirror M that reflects the pulsed illumination light IL that has passed through the relay lens 28B toward the reticle R is disposed,
A condenser lens 32 is arranged on the optical path of the pulse illumination light IL behind the mirror M.

Further, the beam splitter 2 in the illumination system 12
An integrator sensor 46 as an energy detector including a condenser lens 44 and a photoelectric conversion element is arranged on the optical path reflected by the light source 6. That is, in the present embodiment, Japanese Patent Application No.
As in 184221, an integrator sensor 46 as an energy detector is disposed inside an illumination optical system that illuminates a reticle R with pulse illumination light IL from an excimer laser light source 16. As the integrator sensor 46, for example, a PIN-type photodiode or the like having sensitivity in the deep ultraviolet region and having a high response frequency for detecting pulse emission of the excimer laser light source 16 can be used.

The operation of the illumination system 12 configured as described above will be briefly described. A laser beam LB pulse-emitted from an excimer laser light source 16 enters a beam shaping optical system 18 where a rear fly-beam is formed. After its cross-sectional shape is shaped so as to efficiently enter the eye lens 22,
The light enters the energy rough adjuster 20. Then, the laser beam LB that has passed through one of the ND filters of the energy rough adjuster 20 enters the fly-eye lens 22. Thus, a number of secondary light sources are formed at the exit end of the fly-eye lens 22. The pulse illumination light IL as exposure light (exposure illumination light) emitted from the many secondary light sources passes through one of the aperture stops on the illumination system aperture stop plate 24 and has a large transmittance and a high reflectance. Is a small beam splitter 2
To 6. The pulsed illumination light IL transmitted through the beam splitter 26 passes through the first relay lens 28A, the rectangular opening of the fixed reticle blind 30A and the movable reticle blind 30B, and then the second relay lens 28A.
After passing through B, the optical path is bent vertically downward by the mirror M, and then passes through the condenser lens 32 to illuminate the rectangular illumination area 42R on the reticle R held on the reticle stage RST with a uniform illuminance distribution.

On the other hand, the pulse illumination light IL reflected by the beam splitter 26 is received by an integrator sensor 46 via a condenser lens 44,
The photoelectric conversion signal of No. 6 is supplied to the main controller 50 as an output DS (digit / pulse) via a peak hold circuit (not shown) and an analog / digital converter (hereinafter abbreviated as an A / D converter). You. The correlation coefficient between the output DS of the integrator sensor 46 and the pulse energy (exposure amount) per unit area of the pulse illumination light IL on the surface of the wafer W is obtained in advance and provided together with the main controller 50. It is stored in the memory 51.

A reticle R is mounted on the reticle stage RST, and is held by suction via a vacuum chuck (not shown). The reticle stage RST is finely drivable in a horizontal plane (XY plane), and is scanned by a reticle stage driving unit 48 in a predetermined stroke range in a scanning direction (here, the Y direction which is the horizontal direction in FIG. 1). It has become so. The position of the reticle stage RST during this scanning is the same as that of the reticle stage RS.
Measurement is performed by an external laser interferometer 54R via a movable mirror 52R fixed on T, and the laser interferometer 54R
Are supplied to the main controller 50.

The material used for the reticle R needs to be selected depending on the light source used. That is, Kr
When an F excimer laser light source or an ArF excimer laser light source is used as the light source, synthetic quartz can be used.
_When using an excimer laser light source, it must be formed of fluorite.

The projection optical system PL here is composed of a plurality of lens elements having a common optical axis AX in the Z-axis direction arranged so as to have a telecentric optical arrangement on both sides. As the projection optical system PL, one having a projection magnification β of, for example, ４ or ５ is used. Therefore, as described above, when the illumination area 42R on the reticle R is illuminated by the pulse illumination light IL, the pattern of the illumination area 42R formed on the reticle R is projected by the projection optical system PL at a projection magnification β. Reduced image (partially inverted image) has resist (photosensitive material) on the surface
Is formed in the slit-shaped exposure region 42W conjugate with the illumination region 42R on the wafer W on which the light is applied.

[0051] In the case of using a KrF excimer laser light or ArF excimer laser light as the pulsed illumination light IL is as each of the lens elements constituting the projection optical system PL can be employed including synthetic quartz and the like, F ₂ excimer When laser light is used, fluorite is used as the material of the lenses used in the projection optical system PL.

The XY stage 14 is scanned by the wafer stage driving section 56 in the Y direction which is the scanning direction in the XY plane and the X direction which is perpendicular to the scanning direction (the direction perpendicular to the plane of FIG. 1).
Are driven two-dimensionally. A wafer W is held on a Z tilt stage 58 mounted on the XY stage 14 via a wafer holder (not shown) by vacuum suction or the like. The Z tilt stage 58 holds the Z of the wafer W.
Direction position (focus position) and XY
It has a function of adjusting the inclination angle of the wafer W with respect to the plane. The position of the XY stage 14 is measured by an external laser interferometer 54W via a movable mirror 52W fixed on a Z tilt stage 58.
The measured value of W is supplied to the main controller 50.

The wafer W on the Z tilt stage 58
, An uneven illuminance sensor 59 composed of a photoelectric conversion element is permanently provided, and the light receiving surface of the uneven illuminance sensor 59 is set at the same height as the surface of the wafer W. The uneven illuminance sensor 59 has sensitivity in the deep ultraviolet region, and has pulsed illumination light IL.
Can be used to detect PIN. A detection signal of the uneven illuminance sensor 59 is supplied to a main controller 50 functioning as an exposure controller via a peak hold circuit and an A / D converter (not shown).

The control system is mainly constituted by a main controller 50 as a controller in FIG. Main controller 50
Is configured to include a so-called microcomputer (or workstation) composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., so that the exposure operation can be performed accurately. As described above, for example, synchronous scanning of the reticle R and the wafer W, stepping of the wafer W, exposure timing, and the like are collectively controlled. In the present embodiment, the main controller 5
A value of 0 also controls the amount of exposure during scanning exposure, as will be described later.

More specifically, the main controller 50 synchronizes with the scanning of the reticle R via the reticle stage RST in the + Y direction (or the −Y direction) at the speed V _R = V, for example, during scanning exposure. Then, the wafer W is moved in the −Y direction (or + Y direction) with respect to the exposure area 42W via the XY stage 14.
The laser interferometer 54 is scanned at a speed V _W = β · V (β is a projection magnification from the reticle R to the wafer W).
The positions and speeds of the reticle stage RST and the XY stage 14 are controlled via the reticle stage driving unit 48 and the wafer stage driving unit 56 based on the measured values of R and 54W, respectively. Further, at the time of stepping, main controller 50 controls XY stage 14 via wafer stage driving unit 56 based on the measurement value of laser interferometer 54W.
Control the position of.

In the main control unit 50, the control information TS
Is supplied to the excimer laser light source 16 to control the emission power and the like of the excimer laser light source 16 as described later. Further, main controller 50 includes energy rough adjuster 2.
0, the illumination system aperture stop plate 24 is connected to the motor 38 and the driving device 40
, And further controls the opening and closing operation of the movable reticle blind 30B in synchronization with the operation information of the stage system.

As described above, in this embodiment, the main controller 5
0 also serves as an exposure controller and a stage controller. Needless to say, these controllers may be provided separately from main controller 50.

The main controller 50 is provided with a memory 51 as a storage device and an input / output device 62 such as a console. The memory 51 stores a correlation coefficient between the output DS of the integrator sensor 46 and the pulse energy (exposure amount) of the pulse illumination light IL per unit area on the surface of the wafer W. At this time, shot arrangement data of shots on the wafer and shot map data composed of data such as the exposure order of each shot and the scanning direction are stored. Further, in the present embodiment, exposure amount correction data for correcting the non-uniformity of the pattern line width in the scanning direction previously obtained for each of a plurality of shot areas (partition areas) on the wafer W as described later is stored. ing.

Next, a description will be given of a method of creating the exposure amount correction data. First, the same exposure conditions as those in the actual exposure, specifically, the same illumination conditions (selection of the aperture stop by the illumination system aperture stop plate 24 (numerical aperture (NA)), setting of the coherence factor σ value) ), The setting of the width of the illumination area 42R in the non-scanning direction (here, defined by the fixed reticle blind 30A) and the like, using the reticle R used for actual exposure, Is performed by the exposure apparatus 10. At this time, the exposure amount control is performed by the above-described conventional open exposure amount control or pulse-by-pulse control. The wafer W having the pattern transferred to the plurality of shot areas is developed by a coater / developer (not shown). "Shot"
The distribution of the pattern line width in the scanning direction of each of the resist images formed above is measured using a predetermined line width measuring device, for example, a scanning electron microscope (SEM). here,
In measuring the pattern line width, it is desirable to measure an isolated pattern that is more sensitive to the exposure than the line and space (L / S).

When the above test exposure is performed using the reticle R used for the actual exposure, the influence of the scattered light varies greatly depending on, for example, the transmittance of the reticle. For it is important. The test exposure under the same illumination condition is performed, for example, under the illumination condition, more precisely, the numerical aperture (N.D.) of the projection optical system.
A. ), The coherence factor σ, or the type of the reticle pattern, the positions of the light beams passing through the illumination optical system and the projection optical system are different from each other. This is because a difference is generated, which is important for accurately determining the influence of scattered light. Further, performing the test exposure using the exposure apparatus 10 according to the shot map data
This is because other factors such as the synchronization accuracy between the reticle stage RST and the XY stage 14, the arrangement of shot areas on the wafer W, and the like affect the line width of the transferred image.

FIGS. 3A and 3B show an example of the line width distribution in the scanning direction of the shot on the wafer W obtained as a result of the above line width measurement. 3A shows an example of a line width distribution in the scanning direction in a shot of a shot having no adjacent shots on both sides in the scanning direction (hereinafter, referred to as an “isolated shot”), and FIG. B) shows an example of a line width distribution in the scanning direction of a shot in which adjacent shots exist on both sides in the scanning direction. In these figures, the horizontal axis represents the scanning direction position (Y), and the vertical axis represents the line width. Point a on the horizontal axis is one end of the shot (exposure start point)
And point b indicates the other end of the shot (exposure end point).

In this case, the same exposure as described above is separately repeated a plurality of times with different exposure amounts, and from the line width measurement result after the exposure, for example, in the case of a positive resist, the exposure amount as shown in FIG. It is assumed that a correlation function (or conversion rate) between the line width and the line width has been obtained. Thereafter, based on the measurement result of the line width distribution and the known exposure amount and the correlation function of the line width, a computer,
For example, by performing a predetermined calculation using the main controller 50, exposure correction data for correcting the line width distribution in the scanning direction in each shot is obtained for each of the plurality of shots on the wafer W.

In the case of a positive resist, overexposure is observed as a line width thinning phenomenon, and underexposure is observed as a line width thickening phenomenon. Therefore, it is necessary to increase the exposure amount at the position where the line width is large, and to decrease the exposure amount at the position where the line width is small.

As a result, the exposure amount correction data corresponding to the line width distribution in the scanning direction in the shot is obtained as the exposure amount correction data. FIG. 3 (A),
In the case of the shot (B), exposure correction data (exposure correction curves) as shown in FIGS. 5A and 5B are obtained. In FIGS. 5A and 5B, the horizontal axis represents the position (Y) in the scanning direction, and the vertical axis represents the correction amount δ _nm (Y). Here, δ _nm (Y) is the shot array coordinates (n,
m) means the exposure correction value δ at the Y position of the shot.

In this embodiment, an exposure correction curve (exposure correction data) as shown in FIGS.
Is calculated for each of the plurality of shot areas on the wafer W, and these exposure amount correction data are stored in a predetermined storage area in the memory 51 in association with the array coordinates (n, m) of each shot area. ing.

Next, the main control of the exposure sequence when the reticle pattern is transferred to a plurality of shot areas (partition areas) on the wafer W in the scanning exposure apparatus 10 of the present embodiment configured as described above. The control algorithm of the CPU in the device 50 will be described with reference to the flowcharts of FIGS.

First, preconditions and the like will be described.

In the following, since the control is performed centering on the integrator sensor 46 as an energy detector in the scanning type exposure apparatus 10, the processing amount corresponding to the output ES of the energy monitor 16c in the excimer laser light source 16 (this is also E
S) (unit of energy control amount) is [mJ /
pulse]. As described above, the unit of the output DS of the integrator sensor 46 (the unit of the energy control amount) is a digital amount [digit / pulse].

In this case, the output DS of the integrator sensor 46 is previously output on the image plane (ie, on the Z tilt stage 58).
The output of a reference illuminometer (not shown) installed at the same height as the surface of the wafer is calibrated in advance. The data processing unit of the reference illuminometer is [mJ /
(Cm ² · pulse)], and the calibration of the integrator sensor 46 means that the output DS [digit / pulse] of the integrator sensor 46 is converted into the exposure amount [mJ / (c) on the image plane.
m ² · pulse)] to obtain a conversion coefficient (or conversion function). By using this conversion coefficient (or conversion function), the output D of the integrator sensor 46 is calculated.
The exposure amount given on the image plane can be measured indirectly from S. Therefore, in the following, for simplicity, the unit of the exposure amount on the image plane (the processing amount by the integrator sensor 46) indirectly obtained from the output DS of the integrator sensor 46 will be described as [mJ / (cm ² · pulse)]. I do.

Here, the quantities used in the following description are defined as follows. (A) S ₀ : Exposure amount (target exposure amount) to be given to the resist on the wafer to be set by the operator. (B) N: pulse number (exposure pulse number) of the pulse illumination light IL irradiated per one point on the wafer. (C) N _min : the minimum number of exposure pulses per point on the wafer required to obtain the desired exposure amount reproduction accuracy. (D) P: average pulse energy density [mJ on the image plane measured indirectly by the integrator sensor 46 before exposure
/ (Cm ² · pulse)]. (E) E ₀ : the center value of the pulse energy of the excimer laser light source 16 as described above. When the output of the excimer laser light source 16 is E _0, the control amount ES corresponding to the output of the energy monitor 16c also is E _0.

As preconditions, illumination conditions (numerical aperture (NA) of the projection optical system, coherence factor σ) input from an input / output device 62 such as a console by an operator,
The main controller 50 performs setting of an aperture stop (not shown) of the projection optical system PL, selection of an aperture of the illumination system aperture stop plate 24, and the like in accordance with exposure conditions including values and types of patterns. Shall be

Further, based on the shot arrangement, shot size, exposure order of each shot, and other necessary data input by the operator from the input / output device 62 such as a console, shot map data (exposure order and It is assumed that data defining the scanning direction is created and stored in the memory 51. The exposure correction data of each shot under the same conditions as the above exposure conditions is obtained as described above, and these exposure correction data (exposure correction map) are stored in the memory 51 in association with the shot map data. Shall be stored in

The control algorithm shown in FIGS. 6 and 7 starts with wafer exchange, reticle alignment,
It is assumed that a preparation operation for a series of exposures such as baseline measurement, search alignment, and fine alignment is completed.

First, in step 100 in FIG. 6, the process waits until the operator sets the target exposure amount S ₀ for the photoresist on the wafer via the input / output device 62. When the target exposure amount S ₀ is set, the process proceeds to the next step 102, where control information TS is sent to the energy controller 16 d of the excimer laser light source 16, and the energy setting value at the time of pulse emission is set to the central energy E ₀ . Set.

In the next step 104, the XY stage 1
4, the wafer W is retracted from below the projection optical system PL, and the excimer laser light source 16 emits a plurality of (for example, several hundreds) pulses of light through the energy controller 16d. Is integrated and divided by the total number of pulses to indirectly average the pulse energy density P [mJ / (cm ² .Puls.
e)] is measured. At this time, it is assumed that the transmittance of the energy rough adjuster 20 is set to the maximum.

In the next step 106, the number N of exposure pulses per point on the wafer is calculated from the following equation.

N = cint (S ₀ / P) (1)

Here, the function cint is a function for rounding off to one decimal place. Here, rounding is performed because S ₀ / P is not always an integer, but the number of exposure pulses cannot be any other than an integer.

In the next step 108, the above step 1
It is determined whether or not the number N of exposure pulses obtained in step 06 is equal to or more than the required number _{Nmin of} minimum exposure pulses (check). Here, the minimum number of exposure pulses N _min is used to irradiate each point on the wafer W determined based on a known variation of the pulse energy of the excimer laser light source 16 in order to obtain necessary exposure amount control reproduction accuracy. It means the minimum number of pulses of the pulse illumination light IL to be performed.

If the determination in step 108 is denied, that is, if N <N _min , the process proceeds to step 109 and the transmission through the ND filter of the energy coarse controller 20 such that N ≧ N _min is satisfied. After selecting the rate and setting the ND filter, steps 104 to 10 are performed.
8 is repeated.

If the determination in step 108 is affirmative, that is, if N ≧ N _min , the routine proceeds to step 110, where the scanning speed of the wafer W is determined based on the following equation (2).

V _W = D / (N / F) (2)

Here, D is the width in the scanning direction of the slit-shaped exposure area 42W on the wafer W (slit width, F
Indicates the oscillation frequency of the excimer laser light source 16. Since the interval at which the wafer W moves between pulse emission is V _W / F, the number N of exposure pulses is represented by the following equation.

N = D / (V _W / F) (2) ′

That is, the slit width D, the oscillation frequency F, and the scanning speed V are set so that the number N of exposure pulses is obtained.
_W needs to be determined. However, usually the slit width D
Since it is constant, it is sufficient to set at least one of the oscillation frequency F and the scanning speed V _W to stand (2) 'equation, here, to fix the oscillation frequency F to a predetermined oscillation frequency e.g. The scanning speed V _W is determined by calculation. Conversely, for example, the scanning speed V _W
May be fixed (for example, to the maximum speed), and the oscillation frequency F may be determined by calculation.

[0086] In the next step 112, and calculates the target pulse energy E _t during light emission of the average pulse energy (or first pulse setting energy) to obtain the desired S ₀ to be sent with respect to energy controller 16d Send. At this time, the target pulse energy based on the integrator sensor 46 is S ₀ / N, that is, S ₀ / cint (S ₀ / P) using the equation (1). to convert to the target pulse energy E _t on the basis, performs the following normalization.

E _t = (S ₀ / N) · (E ₀ / P) (3)

This normalization is performed by setting the target pulse energy E
_t means that it can be obtained by performing modulation (S ₀ / N) · (1 / P) on the center energy E _{0 in} order to convert the number of pulses into an integer. When the target pulse energy E _t after the normalization is supplied to the energy controller 16d,
The energy controller 16 _d sets the high-voltage power supply 16 to set the target pulse energy at the time of the first pulse emission to Et.
The voltage of e is set (charge-up). In this case, when the minimum number of exposure pulses N _min, for example 30, since the exposure pulse number N is greater than or equal to N _min, the target pulse energy E _t
Varies only about ± 1.5% with respect to the center energy E ₀ at most. In contrast, the variable range of the output of the excimer laser light source 16, since with respect to the central energy E ₀ for example, about ± 10%, the target pulse energy E _t becomes to fall within the variable range with a margin.

In the next step 114, the wafer W is moved according to the shot map data at that time, and the exposure correction data (exposure correction map) of the shot to be exposed (the first shot is the first shot) is stored in the memory. After the data is loaded into the internal memory from 51, the process proceeds to step 116, where the reticle R (reticle stage RST) and the wafer W (XY stage 14) for exposure of the shot area to be exposed on the wafer W advance (ie, scan). Are started, and both are set to their respective target scanning speeds (the wafer W is
A scanning speed V _W determined in 0, the reticle R is accelerated to a is) reciprocal of the speed of the projection magnification beta, and accelerated after the end of the reticle R and the wafer W at a speed ratio corresponding to the projection magnification beta Scan at a constant speed. The processing in step 116 is as follows:
While monitoring the measured values of the laser interferometers 54R and 54W, the reticle stage driving unit 48 and the wafer stage driving unit 56
Done through. Therefore, the laser interferometers 54R, 54R
The measured value of W is continuously supplied to main controller 50 at predetermined intervals from the start of the approach.

Scanning at constant speed between reticle R and wafer W
Is started, the routine proceeds to step 118, where the laser interferometer 5
While monitoring the measured values of 4R and 54W, reticle R and wafer
Wait for C to reach the exposure start position. And Rechi
When the wafer R and the wafer W reach the exposure start position,
Proceeding to step 120, the current laser interferometer 54W
In the Y direction, ie, the exposure position (slit illumination)
Exposure target shot on wafer W corresponding to region 42R)
Y coordinate of the area (hereinafter referred to as “(Y) information of exposure position”)
Correction amount δ of the exposure amount corresponding to_nm(Y) is the internal memory
After reading from the exposure correction map in
2 and the correction amount δ_nmLaser light source 1 using (Y)
1 pulse for the energy controller 16d of No. 6
Energy E _tIs updated according to the following formula, and the updated target
Pulse energy E_t(Y) the energy controller 16
d is transmitted as the target value of the next one pulse.

E _t (Y) = (1 + δ _nm (Y)) × E _t (4)

[0092] Here, E _t is the one obtained in the above (3) (or those that have been updated during the previous pulse emission).

In the next step 124, a light emission trigger is instructed to the energy controller 16d. As a result, a light emission trigger signal is supplied from the energy controller 16d to the high voltage power supply 16e, and pulse light emission is performed from the laser resonator 16a. In this case, the first light emission is (3)
It performed the E _t of formula as a target value.

[0094] In the next step 126, i-th through the integrator sensor 46 (i = 1,2, ...) performs measurement of the pulse energy P _i of an excimer laser light source 16 and the pulse energy P _i by: normalized to pulse energy E _i relative to the control amount of the energy monitor 16c of the inner and (converted), and transmits the pulse energy Ei to the energy controller 16d.

E _i = (P _i / P) · E ₀ (5)

In this case, the coefficient (P _i /
P) corresponds to a variation in energy control for each pulse emission of the excimer laser light source 16, and its coefficient (P _i / P)
Are within the variable range of the output of the excimer laser light source 16.

[0097] Here, normally, the output ES of the energy monitor 16c is (3) matches in a range of variation of the pulse energy to the target energy E _t of expression may necessarily not be thus by optical axis deviation such as is there. Therefore, by detecting the output ES of the energy monitor 16c at an energy controller 16d, by verifying whether the detection result is consistent with (3) the range of variation of the pulse energy to the target energy E _t of formula abnormalities The presence or absence may be detected. And the energy monitor 16
If c output ES is shifted from the target energy E _t exceeds a predetermined allowable range, or the upper limit of the variable range of the output of the output ES excimer laser light source 16, or if almost reached the lower limit, the An alarm signal may be sent from the energy controller 16d to the main controller 50. In this way, according to the alarm signal,
The main controller 50 can stop the scanning exposure and issue an alarm to the operator. In this case, the operator can, for example, adjust the deviation of the optical axis between the excimer laser light source 16 and the exposure main body by the alarm.

In the next step 128, the above step 1
26 Measurement of the pulse energy P _i of or is within the N-th, i.e., it is determined whether i ≦ N. And
If this determination is affirmed, the process proceeds to step 130 to instruct the energy controller 16d in the excimer laser light source 16 to charge up. As a result, the energy controller 16d executes step 12
The voltage applied to the high voltage source 16e for obtaining a target pulse energy E _t updated by 2 is calculated taking into account the state of the state and the chamber of the gas in the laser chamber at that time,
This applied voltage is set (charged up) to the high voltage power supply 16e.

Thereafter, steps 124 to 128
Are repeated, and N pulses are emitted. If the determination in step 128 is negative, the process proceeds to step 132. In this manner, until the number of emission pulses reaches N, the average value of each pulse energy measured by the integrator sensor 46 is a desired value obtained by correcting the wafer energy density P measured first according to the exposure amount correction data. Is performed so as to be substantially equal to.

In step 132, the shot area during exposure is
The laser interferometer 54 determines whether the exposure end point of the region has been reached.
The determination is made based on the measured value of W in the Y direction. And this
If the determination in step 132 is negative,
Proceeding to step 131, the energy in the excimer laser light source 16 is changed.
The next pulse is applied to the energy controller 16d.
Instruct pressure calculation and charge-up. This allows
The energy controller 16d transmits a series of (N−
1) The measured value of the pulse energy for the pulse (that is,
P measured in step 126_iStandardized value)
Then, the target value E of the energy of the next (i + 1) th pulse
_targetIs calculated. As an example, a series of N _minPulse
The integrated value of pulse energy (integrated exposure amount) is calculated by equation (4).
Target pulse energy E_tE using_t・ N_minWill be
Sea urchin target value E_targetTo determine
One of the simple formulas is as follows.

E _target = E _t −Σ (E _n −E _t ) (6)

However, the addition range of the coefficient n of the sum symbol Σ in the equation (6) is from n = (i−Nmin + 2) to n = i. Thereafter, the energy controller 16d operates the high-voltage power supply 1 for obtaining the target value E _target of the pulse energy.
The applied voltage to 6e is calculated in consideration of the state of the gas in the laser chamber and the state of the chamber at that time, and the applied voltage is set to the high voltage power supply 16e (charge up).

Thereafter, the flow returns to step 120, and thereafter, the operations of steps 120 to 132 (excluding step 130) are performed. At this time, a light emission trigger signal is output from the energy controller 16d in response to the light emission trigger command in step 124. The target value E of the pulse energy set in step 131 by the laser resonator 16a
Pulse emission is performed with pulse energy near the _target . Here, the target value E _target, as is apparent from equation (6), include E _t, as the E _t is (4)
Since E _t (Y) updated for each Y position represented by the equation is used, the pulse energy is eventually adjusted along the exposure correction data (exposure correction map).

Thereafter, the operations of steps 120 to 132 (excluding step 130) are continuously repeated during the scanning exposure, and the target value of the next pulse energy of the excimer laser light source 16 is determined based on the output of the integrator sensor 46. Is set, and when the exposure end point is reached in step 132, the pulse emission is stopped, and the exposure of the shot ends. During the exposure of one shot, as described above, the pulse energy is adjusted in accordance with the exposure correction data of the shot, and as a result, control of the integrated exposure in accordance with the exposure correction map is realized. Line width uniformity is improved.

After the exposure of one shot is completed, the flow advances to step 134 to determine whether there is a next shot, that is, a next shot to be exposed, based on the shot map data in the memory 51. If there is, the process returns to step 114 in FIG.
The processes and determinations up to step 134 are repeated, and when the exposure of all shots is completed and the determination in step 134 is affirmed, a series of processes of this routine is completed.

As described above, the scanning exposure apparatus 1 of the present embodiment
According to 0, while the pattern of the reticle R is sequentially transferred to one of a plurality of shot areas (partition areas) on the wafer W by the scanning exposure method, that is, during the scanning exposure, the integrator sensor 46 generates the pulse illumination light IL. The respective energy amounts are sequentially detected, and the energy controller 16d uses the detection result of the integrator sensor 46 to shift by unit pulses (one pulse in the above description) and sequentially shift by N pulses (N is 2 or more). The integral light quantity of the number of irradiation pulses of pulsed illumination light to each point on the wafer W predetermined in accordance with the set exposure amount, for example, N _min ), that is, a series of changes in the integrated light quantity, is calculated. The main controller 50
Adjusting one pulse pulse illumination light pulse energy emitted from the laser resonator 16a so that the cumulative amount of light corresponding to N times the target value E _t of the energy given from.
On the other hand, the main controller 50 measures in advance each of the plurality of shot areas on the wafer W stored in the memory 51 in accordance with the position data of the wafer detected in real time by the wafer interferometer 54W during the scanning exposure. Target value of one pulse energy to be given to the energy controller 16d in accordance with the exposure correction data corresponding to the shot area in the exposure correction data for correcting the nonuniformity of the pattern line width in the scanning direction. To update.
Thereby, the pulse energy of the pulse illumination light is adjusted by the energy controller 16d as described above,
As a result, control is performed so that the exposure amount at each point in the scanning direction of the shot changes in accordance with the exposure amount correction data corresponding to the shot area.

Therefore, according to the present embodiment, as a result of scanning exposure for each shot area on the wafer, the line width uniformity of the pattern transfer image transferred to each shot area in the scanning direction is improved.

In the above description, the respective energy amounts of the pulse illumination light IL are sequentially detected by the integrator sensor 46, and the main controller 50 normalizes the energy amounts according to the scale of the energy monitor 16c in the laser. The calculated value is given to the energy controller 16d, and the energy controller 16d calculates the change in the integrated light amount based on the value. However, the present invention is not limited to this. Of course, it is also possible to detect the change in the integrated light amount for the N pulses up to that time by shifting the unit pulse by using the result. In this case, the arithmetic device and the control device are configured by the main control device 50.

In the scanning exposure apparatus 10 of the present embodiment, the detection result of the integrator sensor 46 in the illumination optical system is directly fed back to the excimer laser light source 16, and the next target value of the pulse energy is set. Therefore, if the energy monitor 1 in the excimer laser light source 16 is
6c and the output of the integrator sensor 46 change even if the correlation is changed.
Exposure amount control is performed with high accuracy based on In other words, a disturbance element generated in the optical system from the excimer laser light source 16 to the integrator sensor 46 can be canceled by the method of directly feeding back the output of the integrator sensor 46. Thereby, the exposure amount control accuracy, that is, the exposure amount control accuracy on the wafer surface is improved.

In the present embodiment, since the integrator sensor 46 is disposed inside the illumination optical system for illuminating the reticle R with the pulse illumination light IL from the excimer laser light source 16, for example, the exposure position on the wafer When the wafer stage WST is moved to change the position, the optical axis shift generated between the excimer laser light source 16 and the exposure apparatus main body causes the energy propagation efficiency from the excimer laser light source 16 to the integrator sensor 46 to fluctuate.
Even if the transmittance or reflectance of the optical member in the illumination optical system generated in the shot area on the wafer and between the shot areas fluctuates, these disturbance elements are canceled on the integrator sensor 46 by direct feedback. Is done.
In addition, the above-described fluctuations mainly occur at a stage before the integrator sensor 46 (on the light source 16 side), and hardly occur at a stage after the integrator sensor 46. Therefore, the fluctuations may lower the exposure amount control accuracy on the wafer. Absent. Such details are disclosed in Japanese Patent Application No. 10-184221.

The above equation (6) is intended to adjust the integrated exposure amount for each N _min pulse to a desired value by the last one pulse. The inventor has previously filed Japanese Patent Application No. 10-1823.
As proposed in No. 06, it is also possible to determine the next target value by performing various weighting so that the closer the pulse, the larger the weight. That is, it is desirable to optimize the control method so that the exposure amount control accuracy and the energy modulation width are reduced to some extent and the load on the excimer laser light source 16 is minimized.

In the present embodiment, the energy controller 16d calculates the integrated light amount for N pulses, for example, N _min pulses, sequentially by shifting one pulse at a time using the detection result of the integrator sensor 46. However, this is in consideration of the fact that the exposure amount control accuracy and, consequently, the line width control accuracy are the highest, but the present invention is not limited to this. A pulse may be used.

By the way, the data of the line width distribution shown in FIGS. 3A and 3B is a factor of the line width variation, specifically, the synchronization error between the reticle stage and the wafer stage during the scanning exposure, and the scanning direction. Is the line width distribution data that reflects all of the forward / reverse of the exposure, the position of the shot area to be exposed on the wafer, the autofocus / autoleveling (AF / AL) control accuracy during scanning exposure, and the effects of flare. .

Therefore, when correcting only the exposure dose error (line width non-uniformity) caused by flare, the following factors are used to separate the remaining line width variation factors from the flare caused line width variation factors. In this manner, the exposure correction data may be created.

As described above, the variation of the exposure amount due to the flare is mainly divided into the case of an isolated shot having no adjacent shot in the scanning direction and the case of a shot having an adjacent shot only on one side in the scanning direction. And shots having adjacent shots on both sides in the scanning direction. Further, shots having shots adjacent only on one side in the scanning direction include shots having shots adjacent only on the scan end point side in the scan direction and shots having shots adjacent only on the scan start point side in the scan direction. And two types are included.

Therefore, for example, if each of the 18 shots on the wafer W arranged as shown in FIG. 8 is to be exposed in a scan direction indicated by an arrow by a so-called perfect alternate scan method, each shot is divided into four shots. Can be grouped into groups. An outline shot (hereinafter, referred to as a "group A shot" for convenience) has adjacent shots on both sides in the scanning direction. Therefore, in this group A shot, as described in the section of the related art earlier, the flare Since the influence of (1) appears almost uniformly in the entire area of the shot, there is almost no variation in the line width in the scanning direction in the shot area due to the flare, and the correction of the exposure amount is not necessarily required.
Also, shots with dotted diagonal lines (hereinafter referred to as “group B shots” for convenience) are isolated shots having no adjacent shots on both sides in the scanning direction (and non-scanning direction). This shot requires an exposure correction near the portion. Shots with solid diagonal lines (hereinafter, referred to as “group C shots” for convenience) are shots requiring exposure correction near the scan end. The remaining shots with diagonal lines of ± 45 ° (double hatching) (hereinafter referred to as “shots of group D” for convenience) are shots requiring exposure correction near the scan start end.

When preparing the exposure correction data for correcting the line width non-uniformity caused by the flare of the shots of the group B, the scanning direction of the shot shown in FIG. The measurement data of the line width distribution in the scanning direction and the measurement data of the line width distribution in the scanning direction of the shots of group A (shots on both sides in the scanning direction) shown in FIG. Figure 3
By subtracting the measurement data of FIG. 3B from the measurement data of FIG. 3A, the data of the line width variation due to the flare of the shot as shown in FIG. 9A is obtained. Next, the obtained data of the line width variation and the correlation function (or conversion rate) between the known exposure amount and the line width shown in FIG.
The exposure correction data is obtained based on the above. As a result, in the case of this example, the exposure amount correction data shown in FIG. 9B is obtained.

When generating exposure correction data for correcting the line width non-uniformity caused by the flare of the shots of the group C and the shots of the group D, similarly to the above, the exposure direction correction data for the shots in the scanning direction is used. The measurement data of the line width distribution and the measurement data of the line width distribution of the shots of the group A in the scanning direction are obtained in advance as described above, and the shots of the group A or the shots of the group D are obtained from the shot data of the group C or the shots of the group D. Subtract the measurement data of
Data on the line width variation of these shots due to flare is obtained. Next, the obtained data of the line width variation,
Exposure amount correction data may be obtained based on a known exposure amount and a line width correlation function (or conversion rate).

As described above, three types of exposure amount correction data for correcting only the exposure amount error (line width nonuniformity) caused by flare can be obtained. When correcting only the exposure error (line width non-uniformity) caused by flare as described above, it is not necessary to prepare individual exposure correction data for all of a plurality of shots on a wafer. Since it is only necessary to prepare three or four types of exposure amount correction data including the groups B to D or the group A added thereto, there is an advantage that the measurement for that is simplified.

By performing scanning exposure according to the flowcharts of FIGS. 6 and 7 using the respective exposure amount correction data for each of the above-described grouped shot areas, the shot areas of groups B, C, and D can be obtained. Is affected by the scattered light of the group A having the shot areas adjacent on both sides in the scanning direction.
Thus, the line width uniformity of each of the plurality of shot areas on the wafer in the scanning direction can be improved. Therefore, in this case, exposure of a so-called dummy shot for improving the line width uniformity of each shot in the scanning direction becomes unnecessary.

Note that the above-mentioned exposure amount correction data is data for uniformly receiving the influence of scattered light regardless of the position in the scanning direction in each shot area. The exposure correction data shown in FIG. 9 (B) is shifted downward until δ _nm (Y) at points a and b becomes 0 (zero), and this exposure correction data is obtained. If the exposure of the shots of the group B is performed using this method, it is possible to ensure the uniformity of the line width while canceling the influence of the flare.

In the above embodiment, the main controller 50
Has described the case where the integrated exposure amount control on the wafer is performed by finely adjusting the pulse energy of each pulse illumination light IL from the excimer laser light source 16 via the energy controller 16d. However, the present invention is not limited to this. The step 50 may adjust the exposure amount by adjusting the number of irradiation pulses applied to each point while each point on the wafer crosses the illumination area of the pulse illumination light IL in the scanning direction. For example, at the time of the scanning exposure, by changing the scanning speed while keeping the power of the excimer laser light source 16 constant and maintaining the speed ratio between the reticle stage RST and the XY stage 14, the exposure amount can be reduced. You only have to make adjustments. Alternatively, the main control device 50 controls the illumination system 1
The same exposure amount control as described above can also be realized by controlling the movable reticle blind 30 </ b> B in 2 and continuously changing the width (so-called slit width) of the illumination area 42 </ b> R in the scanning direction. Alternatively, the main controller 50 may control the exposure amount by controlling the oscillation frequency of the excimer laser light source 16. The main controller 50 can adjust the exposure amount by combining the adjustment of the scanning speed and the adjustment of the slit width.

As described above, in the main controller 50, the oscillation frequency of the laser resonator 16 a of the excimer laser light source 16,
The exposure amount may be adjusted by controlling at least one of the energy per pulse, the scanning speed, and the slit width according to the exposure amount control data obtained in advance.

In the above-described embodiment, a case has been described in which, as the exposure correction data, data for correcting the exposure in accordance with the variation in the line width distribution of each shot area on the wafer measured in advance. However, the present invention is not limited to this. As the exposure amount correction data, the pattern line width is adjusted so that the line width of the central part in the scanning direction in the shot area measured in advance for each of the plurality of shot areas on the wafer is adjusted to the other part. Data to be equalized may be used. In such a case, in any shot area on the wafer, the line width at the center in the scanning direction is uniformly affected by the flare during exposure, but is synchronized with the reticle and wafer during scanning exposure. Since pattern line width errors due to errors, focus tracking errors, and other factors are unlikely to occur, use data that equalizes the pattern line width so that other parts match the line width of such parts as exposure amount correction data. Accordingly, the line width uniformity in the scanning direction for each of the plurality of shot regions on the wafer can be improved to some extent, and the uniformity of the pattern line width between the shot regions can also be improved.

In the above-described embodiment, a case has been described in which the variation in the line width in the scanning direction caused by the flare in each shot area on the wafer W is corrected. Also in the scanning direction, the influence of flare upon exposure of an adjacent shot may cause non-uniformity of the pattern line width in the non-scanning direction. Therefore,
The ideal intensity distribution including flare in the non-scanning direction is obtained based on the line width distribution data measured in advance, and the optical members in the illumination system are driven so that the ideal intensity distribution is obtained before each shot area is exposed. Then, for example, as described in JP-A-8-64517, uneven unevenness is generated, or, for example, as described in JP-A-7-130600,
It is also possible to use a tilt unevenness correction plate to positively generate tilt unevenness to correct the exposure amount distribution in the non-scanning direction. Although the above-mentioned Japanese Patent Application Laid-Open No. Hei 7-130600 does not explicitly describe a scanning exposure apparatus, the tilt unevenness correction plate disclosed in the publication can be suitably applied to a scanning exposure apparatus. is there. By performing the above-described correction in the non-scanning direction together with the above-described exposure amount correction in the scanning direction, the uniformity of the line width in each shot region is further improved. It is better that the exposure intensity distribution in the non-scanning direction is also corrected according to an ideal intensity distribution for each shot.

In the above embodiment, the scanning exposure apparatus and the scanning exposure method using an excimer laser light source which is a kind of pulse light source as the light source have been described. In the case of a scanning type exposure apparatus using continuous light such as an ultraviolet bright line (g-line, i-line) generated by the above as the illumination light for exposure, the above-described control of the exposure amount during the scanning exposure is performed by the above-described scanning speed and slit. It can be easily realized by adjusting at least one of the widths. Alternatively, the output of the lamp light source (lamp power)
Or by controlling a transmittance control element installed in the illumination optical system, for example, a transmittance variable element having two diffraction grating plates whose relative positions can be adjusted, to adjust the exposure amount. Just do it.

Note that the scanning exposure apparatus of the above embodiment is
An illumination optical system and a projection optical system composed of a plurality of lenses are incorporated into the exposure apparatus main body to perform optical adjustment, and a reticle stage and a wafer stage composed of a large number of mechanical parts are attached to the exposure apparatus main body, and wiring and piping are connected. Further, it can be manufactured by performing comprehensive adjustment (electric adjustment, operation confirmation, etc.). In this case, it is desirable to manufacture the exposure apparatus in a clean room in which temperature and cleanliness are controlled.

A semiconductor device is manufactured from a wafer to which a reticle pattern is transferred by using the scanning exposure apparatus of the above embodiment. That is, the semiconductor device
A step of designing the function and performance of the device, a step of manufacturing a reticle based on the design step, a step of transferring a reticle pattern to a wafer by the exposure apparatus 10 of the above-described embodiment, and a step of assembling a device (dicing step, bonding step) , Including a package process), an inspection step, and the like.

Further, according to the present invention, if a scanning exposure apparatus is used, for example, a reflective mask and an all-reflection projection optical system are used, and pulse illumination light in a soft X-ray region having a wavelength of about 5 to 15 nm is used. The present invention is also applicable to an EUV exposure apparatus that transfers a 70-100 nm line and space pattern onto a substrate.

[0130]

As described above, according to the scanning exposure apparatus and the scanning exposure method of the present invention, the line width uniformity in each shot area on the substrate is controlled by controlling the amount of exposure light applied to the substrate. There is an excellent effect that it can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an overall configuration of a scanning exposure apparatus according to an embodiment.

FIG. 2 is a block diagram showing an internal configuration of the excimer laser light source of FIG.

FIG. 3A is a diagram showing an example of a line width distribution in a scanning direction in a shot in which there is no adjacent shot on both sides in the scanning direction, and FIG. 3B is a diagram showing both sides in the scanning direction. FIG. 9 is a diagram showing an example of a line width distribution in the scanning direction of a shot in which a shot adjacent to the shot exists.

FIG. 4 is a diagram showing an example of a correlation function between an exposure amount and a line width in the case of a positive resist.

FIGS. 5A and 5B are FIGS. 3A and 3B, respectively.
FIG. 9 is a diagram showing exposure amount correction data (exposure amount correction curve) corresponding to the line width distribution of FIG.

FIG. 6 is a diagram showing a part of a flowchart showing a control algorithm of a CPU in a main control device when a reticle pattern is transferred to a plurality of shot areas on a wafer.

FIG. 7 is a diagram showing the remaining part of the above flowchart.

FIG. 8 is a diagram for explaining creation of exposure amount correction data for correcting a line width variation caused by flare, and is a diagram illustrating an example of a shot arrangement on a wafer.

9A is a diagram illustrating an example of line width variation data due to a flare of a shot having no shot adjacent to both sides in the scanning direction, and FIG. 9B is a diagram illustrating the data of FIG. 9A; FIG. 7 is a diagram showing an example of exposure amount correction data obtained based on the above.

FIGS. 10A to 10C are diagrams for explaining a conventional technique.

[Explanation of symbols]

Reference Signs List 10: scanning exposure apparatus, 16: excimer laser light source (pulse light source), 16d: energy controller (arithmetic unit), 46: integrator sensor (energy detector), 50: main controller (controller), 51: memory ( Storage device), 54W ... wafer interferometer (position detector),
IL: pulse illumination light; R: reticle (mask); W: wafer (substrate); PL: projection optical system.

Claims (11)

[Claims] 1. A mask and a substrate are synchronously moved along a predetermined scanning direction with respect to an illumination area illuminated by pulse illumination light from a pulse light source, and a pattern formed on the mask is projected via a projection optical system. A scanning type exposure apparatus for transferring the pulsed illumination light during scanning exposure to an energy detector; and a unit pulse using a detection result of the energy detector. An arithmetic unit for calculating an integrated light amount for a predetermined N pulses (N is an integer of 2 or more) sequentially shifted by several numbers; a pattern in the scanning direction measured in advance for each of the plurality of divided regions on the substrate A storage device storing exposure amount correction data for correcting line width non-uniformity; a position detector for measuring a position of the substrate; and a scanning exposure method on one of the divided areas on the substrate. While the mask pattern is successively transferred, based on the series of changes in the integrated light amount calculated by the arithmetic unit and the position data of the substrate detected by the position detector, according to the exposure amount correction data. A control device for controlling the amount of exposure in the scanning direction on the substrate so as to change. 2. The scanning exposure apparatus according to claim 1, wherein the exposure amount correction data is data for correcting nonuniformity of a pattern line width due to an influence of flare. 3. The scanning exposure according to claim 1, wherein the control device controls the exposure amount by finely adjusting a pulse energy of each pulse illumination light from the pulse light source. apparatus. 4. The exposure device according to claim 1, wherein the controller adjusts the number of irradiation pulses applied to each point on the substrate while each point on the substrate crosses an illumination area of the pulse illumination light in a scanning direction. 2. The method according to claim 1, wherein
The scanning exposure apparatus according to any one of claims 1 to 3. 5. The scanning type apparatus according to claim 2, wherein the exposure amount correction data includes at least three types of data corresponding to the presence / absence of an area adjacent to the divided area in the scanning direction. Exposure equipment. 6. The exposure amount correction data is obtained based on a measurement result of a line width distribution of a transfer image of an isolated pattern among transfer images obtained by transferring the pattern of the mask onto a plurality of divided areas on the substrate in advance. 2. The scanning exposure apparatus according to claim 1, wherein the data is data for equalizing the pattern line width of each of the plurality of divided areas. 7. The exposure amount correction data includes a pattern line width such that another portion is matched with a line width of a central portion in a scanning direction in each of the plurality of divided areas on the substrate measured in advance. 3. The scanning exposure apparatus according to claim 1, wherein the data is data for equalizing the data. 8. The apparatus according to claim 1, wherein the energy detector is disposed inside an illumination optical system that illuminates the mask with pulse illumination light from the pulse light source.
The scanning exposure apparatus according to any one of claims 1 to 7. 9. A mask and a substrate are synchronously moved along a predetermined scanning direction with respect to an illumination area illuminated by pulse illumination light, and a pattern formed on the mask is projected onto the substrate via a projection optical system. In the scanning exposure method of transferring to the, while the pattern of the mask is sequentially transferred by a scanning exposure method on an arbitrary partitioned area on the substrate, while sequentially detecting the energy amount of each of the pulse illumination light, On the basis of the detected energy amount, the integrated light amount for the predetermined N pulses (N is an integer of 2 or more) is sequentially calculated by shifting the unit pulse number by one unit pulse, and the change in the calculated series of the integrated light amount and the Controlling the exposure amount in the scanning direction on the substrate based on the position of the substrate and changing the exposure amount in accordance with the exposure amount correction data for correcting the non-uniformity of the pattern line width of the divided area. And a scanning exposure method. 10. Prior to the scanning exposure, a line width distribution of a transfer image of the pattern of the mask transferred to each of the plurality of divided areas on the substrate is measured, and based on the measurement result of the line width distribution. The scanning exposure method according to claim 10, wherein the exposure amount correction amount data of each of the plurality of divided areas is obtained by using the method. 11. The exposure correction data of a partitioned area having no partitioned area adjacent to at least one of the scanning directions on the substrate is obtained by measuring a line width distribution of the partitioned area in the scanning direction with both sides in the scanning direction. The scanning exposure method according to claim 10, wherein the value is obtained by using the measurement result of the line width distribution of a partitioned area having a partitioned area adjacent to the area.