KR20230061248A - Exposure apparatus, exposure method, and method of manufacturing article - Google Patents

Abstract

The present invention provides an exposure device which is advantageous for reducing exposure unevenness occurring on a substrate. The exposure device which performs a plurality of scanning exposures for a same shot area on a substrate comprises: a light source unit periodically emitting pulsed light; and a control unit controlling the plurality of scanning exposures using the pulsed light emitted from the light source unit. In each of the plurality of scanning exposures, in order to at least partially offset exposure unevenness which periodically occurs over the shot area by the plurality of scanning exposures, the control unit changes starting timing of emitting the pulsed light from the light source unit during the scanning exposure in the plurality of scanning exposures according to a cycle of exposure unevenness.

Description

Exposure apparatus, exposure method, and article manufacturing method

The present invention relates to an exposure apparatus, an exposure method, and a method for manufacturing an article.

As a lithography apparatus used in a manufacturing process of semiconductor devices, etc., a scanning exposure apparatus is known that transfers a pattern of an original plate to a resist on a substrate as a latent image pattern by exposing a substrate while relatively scanning the original plate and the substrate via a projection optical system. . Recently, in a scanning exposure apparatus, there are cases in which a substrate coated with a thick film resist is used, and for such a substrate, multiple exposures can be performed to enlarge the DOF (Depth of Field). Multiple exposure is to perform scanning exposure multiple times with respect to the same shot area|region in a board|substrate.

By the way, in a scanning exposure apparatus, there are cases where a light source that periodically emits pulsed light is used. In this case, in each scanning exposure, periodic exposure unevenness in the scanning direction may occur on the shot region of the substrate. In Patent Literature 1, while the substrate moves by a unit amount in the scanning direction, the relationship between the number of pulses irradiated to the substrate and the exposure unevenness is obtained in advance, and based on this relationship, the number of pulses is set so as to reduce the exposure unevenness occurring on the substrate. that is listed. At this time, the number of pulses irradiated to the substrate while the substrate moves by a unit amount in the scanning direction is displayed in units of [pulse/mm], for example, and may be expressed as the number of irradiation pulses hereinafter.

Japanese Patent Laid-Open No. 2010-021211

In the method described in Patent Literature 1, based on the relationship between the number of irradiation pulses and exposure unevenness, a plurality of candidates are determined for the number of irradiation pulses capable of reducing exposure unevenness, and one irradiation pulse number is selected from the plurality of candidates. there is. And, in this method, the larger the number of irradiation pulses selected from a plurality of candidates, the smaller the exposure unevenness can be. However, if the number of irradiation pulses is increased, the scanning speed of the substrate stage needs to be reduced due to, for example, a limitation of the period of pulsed light that can be emitted from the light source, which may be disadvantageous in terms of throughput. Therefore, in a scanning exposure apparatus, a method capable of reducing exposure unevenness even when the number of irradiation pulses is reduced is desired.

Accordingly, an object of the present invention is to provide an exposure apparatus advantageous for reducing exposure unevenness occurring on a substrate.

In order to achieve the above object, an exposure apparatus as one aspect of the present invention is an exposure apparatus that performs multiple scanning exposures on the same shot region on a substrate, comprising: a light source unit for periodically emitting pulsed light; and a control unit that controls the plurality of times of scanning exposure using pulsed light, wherein the control unit controls exposure unevenness that periodically occurs on the shot region in each of the plurality of times of scanning exposure by at least one of the plurality of times of scanning exposure. It is characterized in that the timing of starting emission of pulsed light from the light source unit during scanning exposure is changed in the plurality of scanning exposures in accordance with the cycle of the exposure unevenness so as to partially cancel out.

Other objects or other aspects of the present invention will be clarified by preferred embodiments described below with reference to the accompanying drawings.

According to the present invention, it is possible to provide an exposure apparatus advantageous for reducing exposure nonuniformity occurring on a substrate, for example.

1 is a diagram showing a configuration example of an exposure apparatus;
Fig. 2 is a schematic diagram of scanning exposure using a specific pulse intensity distribution shape, and a diagram showing the relationship between the number of irradiation pulses and exposure unevenness.
Fig. 3 is a diagram showing the relationship between the position of a shot region and exposure unevenness in a scanning direction;
Fig. 4 is a diagram showing the relationship between the position of a shot region and exposure unevenness in a scanning direction;
Fig. 5 is a diagram showing an example of emission start timing in each scanning exposure in a case where the number of scanning exposures is two times in multiple exposures;
Fig. 6 is a diagram showing an example of first exposure non-uniformity generated in each round of scanning exposure;
Fig. 7 is a diagram showing an example in which first exposure unevenness is reduced in Example 1;
Fig. 8 is a diagram showing an example in which second exposure unevenness is reduced in Example 2;
Fig. 9 is a diagram showing an example in which first exposure unevenness and second exposure unevenness are reduced in Example 3;

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. At this time, the following embodiment does not limit the invention concerning the claim. Although a plurality of features are described in the embodiment, not all of these plurality of features are essential to the invention, and a plurality of features may be combined arbitrarily. Moreover, in the accompanying drawings, the same reference numerals are attached to the same or similar components, and overlapping descriptions are omitted.

<About configuration example of exposure apparatus>

Fig. 1 is a diagram showing a configuration example of an exposure apparatus 100 according to an embodiment of the present invention. In the following description, the direction parallel to the optical axis of light emitted from the projection optical system 14 and incident on the substrate 16 is referred to as the Z-axis direction, and two directions orthogonal to each other in a plane perpendicular to the optical axis are referred to as X Axial direction and Y-axis direction. At this time, when described as "X-axis direction" in the following description, it can be defined as including the +X direction and -X direction. The same applies to "Y-axis direction" and "Z-axis direction". In this embodiment, the Y-axis direction is described as the scanning direction.

The exposure apparatus 100 of the present embodiment transfers the pattern of the original plate 12 to a resist on the substrate as a latent image pattern by exposing the substrate 16 while relatively scanning the original plate 12 and the substrate 16. It is a step-and-scan exposure device. Such an exposure apparatus 100 is also called a scanning exposure apparatus or a scanner. In this embodiment, the original plate 12 is, for example, a mask (reticle) made of quartz, and a circuit pattern to be transferred is formed in each of a plurality of shot regions in the substrate 16 . In addition, the substrate 16 is a wafer coated with resist (photoresist), and for example, a single crystal silicon substrate or the like can be used.

A beam of light emitted from the light source unit 1 passes through the beam shaping unit 2, is shaped into a predetermined shape, and enters the incident surface of the optical integrator 3. The light source unit 1 includes, for example, a plurality of laser light sources, and periodically emits pulsed light so that a plurality of pulsed lights are overlapped and irradiated to the substrate 16 while the substrate 16 is scanned by a unit amount. . Further, the optical integrator 3 is constituted by a plurality of minute lenses (e.g., fly-eye lenses), and a number of secondary light sources are formed in the vicinity of its light exit surface.

An aperture turret 4 limits (defines) the size of the surface of the secondary light source by a predetermined aperture. The diaphragm turret 4 is provided with a number such as, for example, an aperture diaphragm having a different circular aperture area, a ring-shaped diaphragm for annular illumination, a quadrupole diaphragm, etc. so that a plurality of types of coherence factor σ values can be set (illumination mode). number) are disposed. Then, when changing the shape of the incident light source of the illumination light, a necessary stop is selected and inserted into the optical path. The light amount detection unit 6 includes, for example, a photoelectric conversion element, and detects a part of the pulsed light reflected by the half mirror 5 as the light amount per pulse (light intensity), and an electrical signal indicating the detection result. (detection signal) is output to the light amount calculation unit 22.

The condenser lens 7 Koehler illuminates the blind 8 with a light flux from a secondary light source near the exit surface of the optical integrator 3. A slit 9 is disposed near the blind 8 to shape the profile of light illuminating the blind 8 into a rectangular shape or an arc shape. Light passing through the blind 8 and the slit 9 (also referred to as slit light) passes through the mirror 10 and the condenser lens 11 to form an image on the original plate 12 on which the pattern is formed in a state where the illuminance and incident angle are uniform. do. The disc 12 is disposed on the conjugate plane of the blind 8 . The opening area of the blind 8 has a similar shape to the light irradiation area of the disc 12 and the optical magnification ratio. During scanning exposure, the blind 8 performs synchronous scanning with respect to the original stage 13 at an optical magnification ratio while shielding the outside of the radiation area of the original plate 12 from light.

The disc 12 is held by the disc stage 13 . The light passing through the original plate 12 is the light (pattern light) that reflects the pattern formed on the original plate 12, and passes through the projection optical system 14 to the exposure field of view area on the pattern surface of the original plate 12 and the optical conjugate plane. is frozen in The focus detection system 15 detects the height and inclination of the exposure surface of the substrate 16 held by the substrate stage 18 . During scanning exposure, the substrate stage 18 is controlled so that the exposure surface of the substrate 16 is positioned on the image plane of the projection optical system 14 based on the information of the focus detection system 15, while the original stage 13 and the substrate stage 18 are synchronously scanned at a speed ratio according to the projection magnification of the projection optical system 14 . In this way, the substrate 16 is exposed to light, and the pattern of the original plate 12 can be transferred to the resist on the substrate 16 as a latent image pattern.

The energy measuring unit 17 is installed on the substrate stage 18 and measures the amount (light intensity) of light emitted from the projection optical system 14 . The energy measurement unit 17 is composed of, for example, a line sensor disposed along the scanning direction of the substrate 16 or a photo sensor movable in the scanning direction of the substrate 16, and its light-receiving surface is It is arranged to substantially coincide with the image plane of the projection optical system 14. In this way, the light intensity distribution per one pulse of light on the imaging plane of the projection optical system 14 can be measured. The light intensity distribution measured by the energy measurement unit 17 may be understood as indicating the light intensity distribution per pulse of light irradiated onto the substrate 16 .

Next, the configuration of the control system 20 in the exposure apparatus 100 of this embodiment will be described. The control system 20 of this embodiment includes a stage control unit 21, a light quantity calculation unit 22, a light source control unit 23, an information input unit 24, a timing determination unit 25, and a main control unit ( 26) may be included.

The stage controller 21 controls the synchronous scanning of the original plate 12 and the substrate 16 in scanning exposure by controlling the driving (Y-axis direction) of the original stage 13 and the substrate stage 18 . The stage control unit 21 may control the driving (Z-axis direction) of the substrate stage 18 so that the exposure surface of the substrate 16 is disposed on the imaging surface of the projection optical system 14 . In addition, based on the electrical signal received from the light amount detection unit 6, the light quantity calculation unit 22 converts the intensity of the pulsed light emitted from the light source unit 1 into a logical value so as to have a target intensity, and outputs the converted value to the light source control unit 23. do.

The light source control unit 23 controls the pulse oscillation frequency and pulse output energy of the light source unit 1 by outputting a trigger signal and/or an applied voltage signal according to a desired amount of pulsed light. The light source control unit 23 includes the light amount output value of the light amount detection unit 6 obtained from the light amount calculation unit 22 and the exposure parameter information (target integrated exposure amount, required integrated exposure amount accuracy, aperture shape, etc.) maintained by the main control unit 26 Based on this, it is possible to determine the trigger signal and/or the applied voltage signal. At this time, the exposure parameter information is input to the main control unit 26 from the information input unit 24 as a man machine interface or media interface, and is also stored.

The timing determination unit 25 acquires a part of the exposure parameter information from the information input unit 24 via the main control unit 26, and based on this information, scanning exposure among a plurality of shot regions in the substrate 16 The exposure start timing for the target shot region to be performed is determined. The exposure start timing may be understood as a timing for starting emission of periodic pulsed light from the light source unit 1 during scanning exposure (emission start timing), and may be simply referred to as "emission start timing" in the following. For example, when the timing determination unit 25 detects the gate signal supplied from the stage control unit 21 and then starts outputting a trigger signal for instructing the start of emission of periodic pulsed light to the light source unit 1 You can control the time interval until The gate signal is a signal indicating that the substrate 16 is disposed at a target position where scanning exposure can be started by controlling driving of the substrate stage 18, and can be output from the stage controller 21. At this time, the timing determination unit 25 may be configured as a part of the light source control unit 23 .

The main control unit 26 is constituted by, for example, a computer having a processor such as a CPU and a storage device such as a memory, and controls each unit of the exposure apparatus 100. For example, the main control unit 26 includes exposure parameters acquired from the information input unit 24, device-specific parameters, light quantity data detected by the light quantity detection unit 6, and light quantity data measured by the energy measuring unit 17. Acquire Then, based on the acquired information and data, various types of information necessary for scanning exposure are calculated and the light source control unit 23 and the stage control unit 21 are controlled. In this embodiment, the stage control unit 21, the light amount calculation unit 22, the light source control unit 23, and the timing determination unit 25 are configured as separate bodies from the main control unit 26, but a part of the main control unit 26 It may be configured as That is, in Fig. 1, all of the stage control unit 21, light amount calculation unit 22, light source control unit 23, timing determination unit 25, and main control unit 26 may be understood as control units.

<About exposure unevenness>

In the exposure apparatus 100, a pattern may be formed on the substrate 16 coated with a thick resist, and in this case, multiple exposures may be performed to enlarge the depth of field (DOF). Multiple exposure is performing scanning exposure multiple times for the same shot region (target shot region) in the substrate 16 . However, when the light source unit 1 that periodically emits pulsed light is used, in each of a plurality of scanning exposures, periodic exposure unevenness in the scanning direction may occur on the target shot region. Therefore, in the exposure apparatus 100, it is required to reduce exposure unevenness that periodically occurs on the target shot region. Here, the exposure unevenness is defined as a deviation (deviation) of the integrated exposure amount of the substrate (target shot region) with respect to the target exposure amount, and can be expressed in a unit of "%".

Fig. 2A shows a schematic diagram of scanning exposure using a specific pulse intensity distribution shape, and Fig. 2B shows the relationship between the number of irradiation pulses and exposure unevenness. The number of irradiation pulses is defined as the number of pulsed lights irradiated while overlapping the substrate 16 while the substrate 16 is scanned by a unit amount (unit distance), and is expressed in units of [pulse/mm], for example. can In the example of Fig. 2A, the number of irradiation pulses is &quot;6&quot;. In addition, the pulse intensity distribution shape is defined as the shape of the intensity distribution of one pulse light output from the light source unit 1 or irradiated onto the substrate, and in the example of Fig. 2A, it is a trapezoidal shape.

The integrated exposure amount at each position in the scanning direction is a value obtained by integrating the energies of a plurality of pulsed lights as shown by hatching in FIG. 2A, and the amount of exposure unevenness (i.e., target The deviation amount of the integrated exposure amount with respect to the exposure amount) is determined. Specifically, as shown in FIG. 2B, as the number of irradiation pulses increases, that is, as the pulse density per unit amount in the scanning direction increases, the influence of the inclined portion of the trapezoidal pulse intensity distribution shape decreases. , exposure unevenness can be reduced. And, in the example of FIG. 2B, it is confirmed that exposure unevenness is greatly reduced when the number of irradiation pulses is 4, 6, or 8 [pulse/mm].

Fig. 3 shows the relationship between the position of the shot region in the scanning direction and the exposure unevenness obtained when scanning exposure is performed once under each condition of the number of irradiation pulses being 4, 6, and 8 [pulse/mm]. As shown in Fig. 3, the maximum value of exposure unevenness generated on the shot region by one scanning exposure is 0.05 [%] or more at 4 [pulse/mm] and 0.03 [%] at 6 [pulse/mm]. ], it becomes less than 0.01 [%] at 8 [pulse/mm]. That is, it can be seen that the maximum value of exposure unevenness decreases as the number of irradiation pulses increases. In addition, exposure unevenness generated on the shot region by one scanning exposure has a periodicity depending on the number of irradiation pulses, and becomes a stripe shape with a period of 250 [μm] when the number of irradiation pulses is 4 [pulse/mm].

Here, the amount of exposure unevenness (maximum value) can be reduced by increasing the number of irradiation pulses, as shown in FIG. However, if the number of irradiation pulses is increased, the scanning speed of the substrate stage 18 needs to be reduced due to limitation of the emission period of pulsed light that can be emitted from the light source unit 1, etc., which may be disadvantageous in terms of throughput. Therefore, a method capable of reducing exposure unevenness even when the number of irradiation pulses is reduced is desired. Therefore, in the present embodiment, exposure unevenness occurring in the shot region is reduced by using multiple exposure in which scanning exposure is performed a plurality of times for the same shot region. Specifically, in each of the plurality of scanning exposures, the emission start timing is set according to the period of the exposure unevenness so that the exposure unevenness that periodically occurs on the shot region is at least partially canceled by the plurality of scanning exposures. change in Thereby, the exposure unevenness which arises in a shot area|region in the whole multiple exposure (scanning exposure multiple times) can be reduced. Hereinafter, examples for reducing exposure nonuniformity will be described.

<Example 1>

Fig. 4 shows the relationship between the position of the target shot region in the scanning direction and exposure unevenness obtained when scanning exposure is performed once with the irradiation pulse light set to 4 [pulse/mm]. In the above-described FIG. 3, only the exposure non-uniformity (first exposure non-uniformity) generated according to the light emission period of the pulsed light emitted from the light source unit 1 is shown, but actually, as shown in FIG. 4, the period is shorter than the first exposure non-uniformity. The resulting exposure unevenness (second exposure unevenness) may overlap with the first exposure unevenness. The first exposure unevenness occurs according to the emission period of the pulsed light emitted from the light source unit 1, and in the example of FIG. 4, it may occur on the shot area at a period of 250 [μs] (spatial period). On the other hand, the second exposure unevenness is caused by the optical integrator 3 and occurs at a shorter cycle than the first exposure unevenness, and in the example of FIG. can occur above At this time, in the first embodiment, an example of reducing the first exposure unevenness is described, and for an example of reducing the second exposure unevenness, in Example 2, both the first exposure unevenness and the second exposure unevenness are reduced. An example is described in Example 3.

First, processing of the timing determination unit 25 for reducing the first exposure unevenness will be described. The timing determination unit 25 acquires information regarding multiple exposures via the main control unit 26 . Information related to multiple exposures, for example, information indicating the number of scanning exposures in multiple exposures (the number of scanning exposures performed for the same shot region), and the period of exposure unevenness to be reduced (spatial period) It may include information indicating a . Information indicating the number of scanning exposures in multiple exposures is input by the user via the information input unit 24 and stored in the main control unit 26, and the timing determination unit 25 stores the information stored in the main control unit 26. This information can be obtained from the main control unit 26. In addition, information indicating the period of exposure unevenness to be reduced is obtained from previous experiments, simulations, etc., and stored in the main control unit 26, and the timing determination unit 25 determines the information stored in the main control unit 26. Information can be acquired from the main control unit 26 .

Next, the timing determination unit 25 determines the emission start timing for each of a plurality of times of scanning exposure in the multiple exposure, based on the acquired information on the multiple exposure. As described above, the emission start timing may be understood as a timing at which the light source unit 1 starts to emit periodic pulsed light according to detection of a gate signal supplied from the stage control unit 21 . That is, the emission start timing may be understood as the time (period) from detecting the rise of the gate signal supplied from the stage control unit 21 until the light source unit 1 starts to emit periodic pulsed light. In addition, the timing determination unit 25 may determine the time shift amount of the emission start timing in multiple times of scanning exposure in multiple exposures. As an example, when the number of scanning exposures in multiple exposures is two, the timing determination unit 25 determines the time of the emission start timing in the second scanning exposure relative to the emission start timing in the first scanning exposure. shift amount can be determined. The information on the emission start timing in each scanning exposure determined by the timing determination unit 25 is supplied to the light source control unit 23 . Then, the light source control unit 23 controls emission of pulsed light from the light source unit 1 in each of a plurality of scanning exposures by controlling a trigger signal based on the information on the emission start timing.

Fig. 5 shows an example of the emission start timing in each scanning exposure in the case where the number of scanning exposures in multiple exposure is two times. The emission start timing shown in Fig. 5 may be understood as the output timing of the trigger signal supplied from the light source control unit 23 to the light source unit 1. The trigger signal may be a signal supplied to the light source unit 1 in order to emit pulsed light to the light source unit 1 (light emission command to the light source unit 1). In the example of Fig. 5, the timing determining unit 25 sets the time from detecting the gate signal to starting the output of the trigger signal to the light source unit 1 (emission start timing), and in the first scanning exposure, the time It is determined by A, and in the scanning exposure of the second time, it is determined by the time obtained by adding the time shift amount B to the time A.

Next, a method for determining the emission start timing in each of a plurality of scanning exposures so as to reduce the first exposure unevenness in the entirety of multiple exposures will be described. In the case of the second embodiment, the timing determination unit 25 sets the emission start timing in a plurality of scanning exposures according to the period of the first exposure unevenness so that the first exposure unevenness is at least partially canceled by the plurality of scanning exposures. change Specifically, the timing determination unit 25 determines the emission start timing when the number of scan exposures in multiple exposures is N, in multiple scan exposures for a time corresponding to 1/N of the cycle of the first exposure unevenness. change Here, as the information indicating the cycle of the first exposure unevenness, information obtained from previous experiments or simulations may be used, but information indicating the emission cycle of the pulsed light emitted from the light source unit 1 may be used. This is because the period of the first exposure unevenness corresponds to the light emission period of pulsed light emitted from the light source unit 1 .

Fig. 6 shows an example of the first exposure non-uniformity occurring in each scanning exposure in a case where the number of scanning exposures is two times in multiple exposures. 6 shows a case where the irradiation pulse light is 4 [pulse/mm] and the light emission period of the pulsed light emitted from the light source unit 1 is 250 [μs] (ie, the pulse oscillation frequency is 4 [kHz]). there is. Further, the first exposure unevenness generated in the target shot region by the first scanning exposure is indicated by a solid line, and the first exposure unevenness generated in the target shot region by the second scanning exposure is represented by a dotted line.

In the example of FIG. 6 , the timing determination unit 25 sets the emission start timing in the second scanning exposure to half the cycle of the first exposure unevenness (with respect to the emission start timing in the first scanning exposure). 125 [㎛]) is determined to deviate by the time corresponding to. That is, the time shift amount B of the emission start timing in the second scanning exposure with respect to the emission start timing in the first scanning exposure corresponds to half (125 [μm]) of the period of the first exposure unevenness. decide on the time to Here, since the first exposure non-uniformity occurs according to the light emission cycle of the pulsed light emitted from the light source unit 1, the light emission cycle of the pulsed light emitted from the light source unit 1 and the number of scanning exposures in multiple exposures Based on this, the time shift amount B can be determined. That is, the time shift amount B can be determined as 125 [μs], which is half (1/2) of the light emission period of the pulsed light emitted from the light source unit 1.

In this way, the phase (position of peaks and valleys) of the first exposure unevenness caused by the second scanning exposure is shifted by 180 degrees from the phase (position of peaks and valleys) of the first exposure unevenness caused by the first scanning exposure. can do. As a result, since the first exposure unevenness caused by the first scanning exposure and the first exposure unevenness caused by the second scanning exposure at least partially cancel each other out, as shown in FIG. 7, multiple times of scanning exposure in multiple exposures. 1st exposure nonuniformity can be reduced in the whole. Fig. 7 is a superposition of the first exposure unevenness caused by the first scanning exposure and the first exposure unevenness caused by the second scanning exposure.

Here, although the case where the frequency|count of scanning exposure in multiple exposure was 2 times was illustrated in the above, the 1st exposure nonuniformity reduction effect can similarly be acquired also in the case of 3 times or more. For example, if the number of scanning exposures in multiple exposures is N times, the time shift amount Sn [μs] of the emission start timing in multiple times of scanning exposures is the light emission period of pulsed light emitted from the light source unit 1 Tp [ μs] can be determined as 1/N of In addition, when the emission start timing in the first scanning exposure is taken as a reference, the time shift amount Sn [μs] of the emission start timing in the nth scanning exposure is the light emission cycle of the pulsed light emitted from the light source unit 1 Tp [ μs] can be determined as (n-1)/N. The following is an example of calculation of the time shift amount Sn in the case of Tp = 250 [μs] and N = 3, 4. At this time, n is any integer (natural number) from 1 to N, and the time shift amount Sn is the same as the time shift amount B in FIG. 5 .

For Tp=250 and N=3: n=(2, 3), Sn=(83, 167)

For Tp=250 and N=4: n=(2, 3, 4), Sn=(63, 125, 188)

<Example 2>

In this Embodiment 2, an example of reducing the second exposure nonuniformity is described. As described above, the second exposure unevenness is caused by the optical integrator 3 and occurs on the target shot region at a period shorter than the period of the first exposure unevenness. In the second embodiment, as in the first embodiment, the timing determining unit 25 acquires information regarding multiple exposures, and based on this information, the emission start timing in each of the plurality of scan exposures in the multiple exposures. decide However, in this Embodiment 2, information indicating the period of the second exposure nonuniformity is used as the information indicating the period of exposure nonuniformity to be reduced. The information indicating the cycle of the second exposure unevenness is obtained from previous experiments, simulations, etc. and stored in the main control unit 26, and the timing determination unit 25 uses this information stored in the main control unit 26 as a main control unit. It can be obtained from the control unit 26.

In the case of the second embodiment, the timing determining unit 25 sets the emission start timing in a plurality of scanning exposures according to the period of the second exposure unevenness so that the second exposure unevenness is at least partially canceled by the plurality of scanning exposures. change Specifically, when the number of scan exposures in multiple exposures is N times, the timing determining unit 25 sets the emission start timing to a plurality of scan exposures for a time corresponding to 1/N of the period of the second exposure unevenness. change in For example, it is assumed that the number N of scanning exposures in multiple exposures is twice, and the period Te of the second exposure unevenness is 35 [μm]. In this case, the timing determination unit 25 sets the emission start timing in the second scanning exposure to half (17.5 [μm) of the cycle of the second exposure unevenness with respect to the emission start timing in the first scanning exposure. ]) is determined to deviate by the time corresponding to That is, the time shift amount Sn of the emission start timing in the second scanning exposure with respect to the emission start timing in the first scanning exposure corresponds to half (17.5 [μm]) of the period of the second exposure unevenness. decide on the time to

In this way, the phase (position of peaks and valleys) of the second exposure unevenness generated in the second scanning exposure is shifted by 180 degrees with respect to the phase (position of peaks and valleys) of the second exposure unevenness generated in the first scanning exposure. can do. As a result, since the second exposure unevenness caused by the first scanning exposure and the second exposure unevenness caused by the second scanning exposure at least partially cancel each other out, as shown in FIG. 8, multiple times of scanning in multiple exposures In the whole exposure, the 2nd exposure nonuniformity can be reduced. Fig. 8 is a superposition of the second exposure unevenness caused by the first scanning exposure and the second exposure unevenness caused by the second scanning exposure.

Here, the calculation formula of time shift amount Sn is demonstrated. The calculation formula of the time shift amount Sn can be generalized in Example 1 and Example 2, and can be expressed by the following formula (1). Further, taking the emission start timing in the first scanning exposure as a reference, the calculation formula for the time shift amount Sn of the emission start timing in the nth scanning exposure (n is any one integer from 1 to N) is: It can be expressed by the following formula (2). Each of the following formulas (1) to (2) is used to calculate the time shift amount Sn for reducing either the first exposure unevenness described in Example 1 or the second exposure unevenness described in Example 2. can be used

Sn={Tp×Te/(1/Pm)}×1/N … (One)

Sn={Tp×Te/(1/Pm)}×(n-1)/N … (2)

Tp [μs]: Light emission period of pulsed light emitted from the light source unit 1

Pm [pulse/mm]: number of irradiation pulses

Te [μm]: cycle of exposure unevenness to be reduced

n [th]: any one integer from 1 to N

N [times]: number of scanning exposures in multiple exposures

Sn[μs]: time shift amount

For example, the number of scanning exposures N in multiple exposure is set to 2 times, the irradiation pulsed light Pm is set to 4 [pulse/mm], and the emission period Tp of the pulsed light emitted from the light source unit 1 is set to 250 [μs]. Assume the case of In this case, as described in Example 1, the time shift amount Sn for reducing the first exposure nonuniformity (period Te: 250 [μm]) is Sn = {Tp×Te/(1/Pm)}×1/N = {250 × 250/(1/4 × 1000)} × 1/2 = 125 [μs]. In addition, as described in Example 2, the time shift amount Sn for reducing the second exposure nonuniformity (period Te: 35 [μm]) is Sn = {Tp×Te/(1/Pm)}×1/N= {250 × 35/(1/4 × 1000)} × 1/2 = 17.5 [μs].

<Example 3>

In this Embodiment 3, an example in which both the first exposure unevenness and the second exposure unevenness are simultaneously reduced is described. Also in the third embodiment, as in Embodiments 1 and 2, the timing determining unit 25 acquires information regarding multiple exposures, and based on this information, emits light in each of a plurality of times of scanning exposure in multiple exposures. Determine start timing. However, in this Embodiment 3, as information indicating the period of exposure unevenness to be reduced, information indicating the period of the first exposure unevenness and information indicating the period of the second exposure unevenness are used. Then, the timing determination unit 25 starts light emission according to the cycle of the first exposure unevenness and the cycle of the second exposure unevenness so that the first exposure unevenness and the second exposure unevenness are at least partially canceled by a plurality of scanning exposures. The timing is changed in multiple times of scanning exposure.

Specifically, the timing determining unit 25 calculates, when the number of scanning exposures in multiple exposures is N times, 1/N of the cycle of the first exposure unevenness among odd multiples of 1/N of the cycle of the second exposure unevenness. The time shift amount Sn is determined based on a value close to (preferably the closest value) to . For example, it is assumed that the number N of scanning exposures in multiple exposure is two, the period of the first exposure unevenness is 250 [μm], and the period of the second exposure unevenness is 35 [μm]. In this case, the value (119 [μm]) closest to the half value of the period (250 [μm]) of the first exposure non-uniformity among odd multiples of the half value of the period of the second exposure non-uniformity (35 [μm]) is reduced. It is set as period Te of the exposure nonuniformity to be carried out, and the time shift amount Sn is determined by the above formula (1) or formula (2). Accordingly, since exposure unevenness (first exposure unevenness, second exposure unevenness) occurring in each scanning exposure at least partially cancels each other in these multiple times of scanning exposure, as shown in FIG. 9, multiple exposure in multiple exposures This exposure nonuniformity can be reduced in the whole scanning exposure of a time.

Here, in the above, the case where there are two types of periodic components of exposure unevenness has been described, but M types of periodic components of exposure unevenness (M is an integer of 3 or more) may exist. In this case, the timing determining unit 25 determines the periodicity of each 1/N of the second shortest periodic component to the Mth shortest periodic component from odd multiples of 1/N of the shortest periodic component among the M types of periodic components. Choose the value closest to the multiple. And the amount of time shift Sn is determined by said Formula (1) or Formula (2) using the selected value as period Te of exposure nonuniformity to be reduced. By using the time shift amount Sn determined in this way, exposure nonuniformity of all periodic components can be reduced.

As described above, in the present embodiment, exposure unevenness occurring in the shot region is reduced by using multiple exposure in which scanning exposure is performed a plurality of times for the same shot region. Specifically, in each of the plurality of scanning exposures, the emission start timing is set according to the period of the exposure unevenness so that the exposure unevenness that periodically occurs on the shot region is at least partially canceled by the plurality of scanning exposures. change in Thereby, the exposure unevenness which arises in a shot area|region in the whole multiple exposure (scanning exposure multiple times) can be reduced. At this time, as described in Examples 1 to 3, the time shift amount Sn is based on the period component of exposure unevenness calculated from the pulse intensity distribution shape, the number of irradiation pulses, and the design information of the optical member (optical integrator, etc.) You may decide, but it is not limited to that. For example, you may determine time shift amount Sn based on the result of Fourier analysis of the image obtained by observing the board|substrate which performed the scanning exposure of the 1st time with a scanning electron microscope (SEM).

<Embodiment of manufacturing method of article>

The method for manufacturing an article according to an embodiment of the present invention is also suitable for manufacturing an article, such as a micro device such as a semiconductor device or an element having a microstructure, for example. The method for manufacturing an article of the present embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate using the exposure apparatus (exposure method) described above (step of exposing the substrate), and a substrate on which the latent image pattern is formed in this step. It includes a process of developing (processing). In addition, this manufacturing method includes other well-known processes (oxidation, film formation, vapor deposition, doping, planarization, etching, resist removal, dicing, bonding, packaging, etc.). Compared with conventional methods, the method for manufacturing an article of the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article.

The present invention is not limited to the above embodiments, and various changes and modifications are possible without departing from the spirit and scope of the invention. Accordingly, the claims are appended to clarify the scope of the invention.

Claims (11)

An exposure apparatus that performs scanning exposure multiple times for the same shot region in a substrate, comprising:
A light source unit that periodically emits pulsed light;
A control unit for controlling the plurality of scanning exposures using pulsed light emitted from the light source unit;
The controller controls the exposure unevenness during the scanning exposure according to the period of the exposure unevenness so that the exposure unevenness periodically occurring on the shot region in each of the plurality of times of scanning exposure is at least partially offset by the plurality of times of scanning exposure. An exposure apparatus characterized in that the timing of starting emission of pulsed light from the light source unit is changed in the plurality of scanning exposures.
According to claim 1,
The exposure non-uniformity includes a first exposure non-uniformity generated according to an emission period of pulsed light emitted from the light source unit;
wherein the controller changes the emission start timing from the plurality of times of scanning exposure according to a period of the first exposure unevenness so that the first exposure unevenness is at least partially offset by the plurality of scanning exposures. Device.
According to claim 2,
Wherein the control unit determines the time shift amount of the emission start timing in the plurality of scanning exposures based on the light emission cycle of the pulsed light emitted from the light source unit and the number of scanning exposures for the shot region. exposure device.
According to claim 1,
The exposure unevenness includes second exposure unevenness that occurs at a shorter period than the first exposure unevenness cycle that occurs according to the emission cycle of the pulsed light emitted from the light source unit;
wherein the controller changes the emission start timing from the plurality of times of scanning exposure according to a cycle of the second exposure unevenness so that the second exposure unevenness is at least partially offset by the plurality of scanning exposures. Device.
According to claim 4,
The control unit controls the light emission period of the pulsed light emitted from the light source unit, the period of the second exposure non-uniformity, the number of pulsed lights irradiated to the substrate while the substrate is scanned by a unit amount, and the scanning exposure for the shot area An exposure apparatus characterized by determining a time shift amount of the emission start timing in the plurality of times of scanning exposure based on the number of times of exposure.
According to claim 1,
The exposure unevenness includes a first exposure unevenness that occurs according to a light emission cycle of pulsed light emitted from the light source unit, and a second exposure unevenness that occurs at a shorter period than the first exposure unevenness period,
Based on a value close to 1/N of the period of the first exposure non-uniformity among odd multiples of 1/N of the period of the second exposure non-uniformity when N is the number of scanning exposures for the shot region to determine the time shift amount of the emission start timing in the plurality of scanning exposures.
According to any one of claims 1 to 6,
The control unit determines the light emission period of the pulsed light emitted from the light source unit Tp, the period of exposure unevenness to be reduced Te, the number of pulsed light irradiated to the substrate while the substrate is scanned by a unit amount Pm, and When the number of scanning exposures for the shot region is N, the time shift amount Sn of the emission start timing in the plurality of scanning exposures is
Sn={Tp×Te/(1/Pm)}×1/N
An exposure apparatus characterized in that it is determined by
According to any one of claims 1 to 6,
The exposure apparatus according to claim 1 , wherein the control unit changes the emission start timing by controlling the light source unit.
According to any one of claims 1 to 6,
The exposure apparatus according to claim 1 , wherein the light source unit periodically emits pulsed light so that a plurality of pulsed lights are overlapped and irradiated to the substrate while the substrate is scanned by a unit amount.
An exposure method in which scanning exposure is performed a plurality of times for the same shot region in a substrate using pulsed light periodically emitted from a light source unit, comprising:
In each of the plurality of scanning exposures, the exposure unevenness periodically occurring on the shot region is at least partially canceled by the plurality of scanning exposures, according to the period of the exposure unevenness, the light source unit during the scanning exposure; An exposure method characterized in that the pulsed light emission start timing is changed in the plurality of scanning exposures.
An exposure step of exposing a substrate using the exposure method according to claim 10;
A processing step of processing the substrate exposed in the exposure step,
A method for manufacturing an article, characterized in that an article is manufactured from the substrate processed in the processing step.

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