JP2000021742A - Method of exposure and exposure equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expose a plurality of patterns to a substrate to be exposed to produce a superposed pattern on the same shot, by dividing a luminous flux emitted from a single light source into each for each pattern, which is illuminated separately by a divided luminous flux, wherein desired exposing conditions are set up for each luminous flux by an optical system located in an optical path of each divided luminous flux. SOLUTION: In exposing a plurality of patterns substantially concurrently on a substrate to be exposed, a luminous flux emitted from a single exposure light source 1 is divided into each for each pattern, which is illuminated separately by a divided luminous flux, and desired exposing conditions are set up for each luminous flux by each of optical systems 9, 10 located in an optical path of each luminous flux. The words 'substantially concurrently' in a static exposure (batch exposure) obviously includes the case where the longest pattern exposure time covers exposure times of all other patterns, and also includes the case where at least a part of exposure times of all patterns is concurrent, i.e., superposed. As stated above, a plurality of patterns are exposed substantially concurrently using a plurality of illumination systems.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exposure method and an exposure apparatus, and more particularly to an exposure method and an exposure apparatus for exposing a fine circuit pattern onto a substrate to be exposed. Such an exposure method and an exposure apparatus are used, for example, in the manufacture of various devices such as semiconductor chips such as ICs and LSIs, display elements such as liquid crystal panels, detection elements such as magnetic heads, and imaging elements such as CCDs.

[0002]

2. Description of the Related Art At present, the mainstream of a projection exposure apparatus used for manufacturing devices such as ICs, LSIs and liquid crystal panels by using a photolithography technique uses an excimer laser as a light source. However, in a projection exposure apparatus using this excimer laser as a light source, a line width of 0.1
It is difficult to form a fine pattern of 5 μm or less.

In order to increase the resolution, it is theoretically necessary to increase the NA (numerical aperture) of the projection optical system or to reduce the wavelength of the exposure light. It is not easy to reduce the wavelength of the exposure light. That is, the depth of focus of the projection optical system is inversely proportional to the square of NA and proportional to the wavelength λ.
Is increased, the depth of focus becomes smaller, focusing becomes difficult, and productivity decreases. Also, the transmittance of most glass materials is extremely low in the far ultraviolet region, for example, λ = 248
Even fused silica used in nm (KrF excimer laser) drops to almost zero below λ = 193 nm. At present, a glass material that can be used practically in a region of an exposure wavelength λ = 150 nm or less corresponding to a fine pattern having a line width of 0.15 μm or less by ordinary exposure has not been realized.

Therefore, by performing double exposure of two-beam interference exposure and normal exposure on the substrate to be exposed, and by giving a multi-level exposure amount distribution to the substrate to be exposed at that time, higher resolution is achieved. Is disclosed in Japanese Patent Application No. 9-304232, "Exposure method and exposure apparatus".
(Hereinafter referred to as the prior application). According to this method, a pattern having a minimum line width of 0.10 μm can be formed by using a projection exposure apparatus in which the exposure wavelength λ is 248 nm (KrF excimer laser) and the image side NA of the projection optical system is 0.6. .

[0005]

By the way, in the embodiment of the prior application, the two-beam interference exposure is performed by so-called coherent illumination using a phase shift mask having a line width of 0.1 .mu.mL & S (line and space), and then the minimum line is exposed. Normal exposure (for example, exposure by partial coherent illumination) is performed using a mask on which a real element pattern having a width of 0.1 μm is formed. As described above, the double exposure method requires two exposure steps under different exposure conditions for each shot in order to form one pattern. The prior application proposes a method using two exposure apparatuses and a method using the illumination system of one exposure apparatus by switching. However, in the double exposure method of the prior application, even when one exposure apparatus is used, the exposure is performed by switching the illumination system. SUMMARY OF THE INVENTION It is an object of the present invention to improve the throughput of a multiple exposure method in which a plurality of types of patterns are overprinted on the same shot on a substrate to be exposed to form one type of pattern.

[0006]

In order to achieve the above object, according to the present invention, a plurality of patterns are printed substantially simultaneously using a plurality of illumination systems. More specifically, when a plurality of patterns are exposed on a substrate to be exposed substantially simultaneously, a light beam emitted from a single exposure light source is divided, each pattern is illuminated with a separate light beam, and each of the divided light beams is Desired exposure conditions are set for each light beam by an illumination system arranged in the optical path.

The term “substantially simultaneous” in the present invention means, in static exposure (batch exposure), not only the case where the exposure period of the pattern having the longest exposure time includes the exposure period of all other patterns but also all the exposure periods. This includes a case where at least a part of the pattern exposure period is simultaneous, that is, overlaps. In the scanning exposure, if a plurality of patterns are exposed in one scan, even if a plurality of patterns are arranged in the scanning direction and they are sequentially exposed with a time difference, the present invention is not limited to this. It is included in the “substantially simultaneous” of the invention.

[0008]

In a preferred embodiment of the present invention, at least one of the plurality of patterns is a pattern of a type having different exposure conditions from other patterns. Further, the exposure condition includes an exposure amount, and each exposure amount is obtained by setting the transmittance of the dimming unit in which the transmittance changes discretely for each of the divided light beams and the amount of light emitted from the exposure light source to the desired exposure value. Calculate according to the amount, set the transmittance of each dimming unit, set the division ratio to each light flux to a value corresponding to the calculated ratio of the emitted light amount, and divide the emitted light amount of the light source into the divided light amount. The amount of change in the light amount for each light beam from the calculated output light amount due to the change in the ratio is set to a corrected value. Alternatively, the same is true up to setting the transmittance of each dimming unit. Thereafter, the output light amount of the light source is set to the output light amount calculated for one of the divided light fluxes, and For each light beam other than the split light beam, a light reducing means whose transmittance continuously changes in the light path for each light beam is arranged, and the light emitting amount and the set light emitting amount are calculated by calculating the transmittance of the light reducing means. Is set so as to correct the difference.

An exposure apparatus according to a preferred embodiment of the present invention is a scanning or stationary multiple exposure apparatus using a pulse light source such as a KrF excimer laser as a light source.

[0010]

According to the present invention, a plurality of patterns can be exposed at substantially the same time even when their exposure conditions are different, so that the throughput is much higher than in the conventional case where each type of pattern is separately exposed. Can be improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 shows the configuration of a scanning multiple exposure apparatus according to one embodiment of the present invention. In the figure, reference numeral 1 denotes a light source, for example, Kr
It is a pulse light source such as an F excimer laser. 2 is a polarization beam splitter, 3 and 4 are dimming filters, 5 and 7 are half mirrors, 6 and 8 are light quantity sensors, 9 and 10 are illumination optical systems, 11 and 12 are reticles, 13 is a beam splitter,
14 is a projection lens, and 15 is a wafer. Here, the polarization beam splitter 2 applies p-polarized light to an illumination system (hereinafter, referred to as a first illumination system) that illuminates the reticle 11, and the reticle 1
Lighting system (hereinafter, referred to as a second lighting system) to illuminate 2
It is assumed that polarized light is incident. Reticles 11 and 12 are mounted on a reticle stage, and wafer 15 is mounted on a wafer stage, respectively, and reticle (that is, reticle stage) 1
1, 12 and the wafer (ie, wafer stage) 15 are projected at a speed ratio corresponding to the magnification of the projection lens 14.
By scanning the object surface and the image surface in synchronization with each other in opposite directions, the pattern images of the reticles 11 and 12 are exposed on the wafer 15. The beam splitter 13 is for projecting the pattern images of the reticles 11 and 12 via the projection lens 14 onto two shot positions on the wafer 15. The reticle stage also has a mechanism for moving in the Z direction (a direction parallel to the optical axis) to correct the focus difference between the reticles 11 and 12.

The exposure apparatus shown in FIG. 1 uses two reticles simultaneously, has two illumination systems and two reticle stages corresponding to each of the two reticles, and has a light transmittance and σ (of the illumination optical system). Except that the ratio of the exit-side aperture angle to the entrance-side aperture angle of the projection optical system is varied for each illumination system, it is basically configured and operates in the same manner as a conventional scanning type exposure apparatus. Although the exposure apparatus shown in FIG. 1 can be used even when the pattern images of two reticles are the same, it is particularly effective when two reticles having different exposure conditions are exposed in one scan. Exposure in one scan refers to a case where two reticle patterns are arranged in parallel with the scanning direction and two adjacent reticle patterns are simultaneously exposed in a direction orthogonal to the scanning direction on the wafer. When two shots arranged in series and adjacent to each other in the scanning direction on a wafer or arranged with one or more shots interposed therebetween are continuously exposed, two reticle patterns may be simultaneously exposed to one shot. including.

A minimum line width of 0.1 using the exposure apparatus of FIG.
When transferring a fine pattern of μm onto a wafer, a reticle similar to the conventional one is used as the reticle 11, except that a pattern having a narrow minimum line width of 0.1 μm is formed. On the other hand, as the reticle 12, a reticle having a so-called Levenson type phase shift pattern (diffraction grating) is used. In this case, the optimal σ of the illumination system that illuminates the reticle 12 is 0.3 to 0.2, the optimal σ of the illumination system that illuminates the reticle 11 is 0.6 to 0.8, and It has been confirmed by experiments of the present inventors that the optimum exposure amount is two to three times that of the reticle 12. Therefore, σ of each illumination system is set to an appropriate value.
The setting of σ is performed by selecting, for example, the opening degree and shape of the aperture according to the conventional method.

Next, referring to FIGS. 2 and 3, reticle 1
An exposure condition setting process for setting the exposure amounts 1 and 12 will be described. Here, the target exposure amount D of the reticle 11
A case will be described in which the case 1 is greater than or equal to the target exposure dose Dose2 of the reticle 12 (Dose1 ≧ Dose2), and the dimming filters 3 and 4 use discrete dimming means whose transmittance is discretely switched. Here, as such discrete type dimming means, here, a plurality of ND filters having different transmittances are arranged on a disk, and by rotating this disk, the ND filters located in the illumination light path are sequentially switched. Is used. Also,
Before executing these processes, the exposure amount (nominal dose amount DoseNom) under the conditions of no ND filter (or 100% transmittance of the ND filter), a nominal oscillation frequency FNom, and a nominal scan speed SpeedNom of each illumination system. ) Is measured.

In scanning exposure using a pulse light source, assuming that the scanning speed and the amount of light per pulse of the pulse light source are constant, the oscillation frequency and the amount are in a proportional relationship. Further, when the output of the pulse light source is discretely changed by the dimming means (such as an ND filter), the relationship between the oscillation frequency and the dose is as shown in FIG. In FIG.
The horizontal axis represents the dose (Dose), and the vertical axis represents the oscillation frequency (Freq) of the pulse light source, which is in a proportional relationship. When the oscillation frequency of the pulse light source is reduced, the dose decreases in proportion thereto. For the oscillation frequency, the upper limit value F _MAX based on the maximum emission frequency is defined as the rated value of the light source device.
In addition, the lowest emission frequency F _MIN in consideration of uneven light emission is determined by design. Therefore, when the dose changes and the oscillation frequency changes, the maximum frequency F _MAX or the minimum frequency F
_Get caught in the _MIN limit. In this case, the transmittance of the dimming means is switched to reduce or increase the amount of light per pulse, and change to an adjacent proportional straight line.

Referring to FIG. 2, the exposure condition setting process is started, and when target light amounts (Dose1, Dose2) are input (step S1), preferred exposure conditions for each illumination system are set.
That is, the pulse oscillation frequency and the ND filter value are calculated. FIG. 3 shows details of the exposure condition calculation process. In the exposure condition calculation processing of FIG. 3, an oscillation frequency for performing an optimal exposure using one illuminating system (here, a first illuminating system for illuminating the reticle 11) using an ND filter having a transmittance Nd [i]. FTemp = (Dose × Speed)
× FNom) / (DoseNom × SpeedNom ×
Nd [i]) is calculated. Here, Dose is a dose amount, Speed is a scan speed, FNom is a nominal oscillation frequency, DoseNom is a nominal dose amount, S
speedNom is the nominal scan speed, Nd
[I] is the transmittance of the i-th ND filter. Exposure conditions are calculated in order from the first ND filter. If the calculated FTemp is equal to or higher than the minimum oscillation frequency F _MIN and equal to or lower than the maximum oscillation frequency F _MAX , this FTemp is set to the first
Is determined as the calculated value (Freq1) of the oscillation frequency of the illumination system, and the number of the ND filter used in the illumination system is also determined to the number i at that time, and the exposure condition calculation processing ends. If FTemp is smaller than the minimum oscillation frequency F _MIN or larger than the maximum oscillation frequency F _MAX , i
Of the oscillation frequency FTemp and the calculated value FTem when the light is reduced by the next ND filter
The comparison between p and F _MAX and F _MIN is repeated. Last (i
= ND _MAX ), the calculated value FTe
mp is _{equal to} or higher than the minimum oscillation frequency F _MIN and the maximum oscillation frequency F
If the value does not fall within the range of _MAX or less, there is no appropriate oscillation frequency, so it is determined that there is no solution (NG), and the exposure condition calculation processing ends. When the above-described processing is completed for one illumination system, FTemp and i are similarly determined for the other illumination system (here, the second illumination system that illuminates the reticle 12), and these are determined by Fre respectively.
q2 and j. Note that the above-described calculation order is an example, and any one of the first and second illumination systems may be used first. When the exposure condition calculation processing is completed for both illumination systems, the processing returns to the processing in FIG.

Referring to FIG. 2, if the result of the above exposure condition calculation is that the oscillation frequency calculation result of at least one of the illumination systems is "NG", error-free error processing such as sounding an alarm is executed. This exposure condition setting processing ends. If the oscillation frequencies Freq1 and Freq2 of both illumination systems have been calculated, then Freq1 and Freq2 are compared. If Freq1 = Freq2, the oscillation frequencies suitable for both illumination systems are the same. Therefore, the oscillation frequency Freq of the light source 1 is set to Freq1 (= Freq2), and the number of the ND filter used in each illumination system is also i. And j.

FIGS. 4 and 5 show the respective oscillation frequencies Freq.
1 shows the relationship between Freq2 and target light amounts Dose1 and Dose2. 4 and 5, the ND filter Nd1
When the ND filter is determined to be Nd1 and the oscillation frequency to be Freq1 with respect to the target light amount Dose1 of the first illumination system, as indicated by a white circle on the straight line Nd1 indicating the exposure amount (Dose) / oscillation frequency (Freq) characteristic of In addition, the target light amount Dose2 of the second illumination system different from the target light amount Dose1 of the first illumination system is conveniently adjusted to the straight line Nd2 of FIGS.
As shown by the upper black circle, the ND filter Nd2 rarely calculates the same oscillation frequency Freq1. In many cases, the oscillation frequency Freq2 of the second illumination system
Is Fr as shown by the white circle on the straight line Nd2 in FIGS.
A value different from eq1 is calculated. At this time, since there is one pulse light source, the oscillation frequencies Freq1 and Freq2 cannot be simultaneously realized, and a desired exposure result cannot be obtained as it is. In order to eliminate this drawback, the light amount ratio per pulse incident on the first and second illumination systems is changed.

In the apparatus shown in FIG. 1, the polarizing beam splitter 2
, The ratio p: s of the light (p-polarized light) reflected by the polarization beam splitter 2 and the light (s-polarized light) transmitted therethrough is continuously varied. Referring to FIG. 2, when the calculation result of the exposure condition is not Freq1 = Freq2, the polarization beam splitter 2 is rotated around its normal line to a position where its polarization characteristic becomes p: s = Freq1: Freq2. Then, the oscillation frequency Freq of the pulse light source 1 is set to s ₀ × Freq2 / s, and the numbers of the ND filters used in the respective illumination systems are i and j.
And terminate the process. Here, p ₀ : s ₀
Is the ratio of p-polarized light to s-polarized light, which is a prerequisite when calculating Freq1 and Freq2, and p ₀ + s ₀ =
Let p + s = 100. s ₀ : p ₀ is, for example, 50:50
Set to. The ND filters used in each illumination system have numbers i and j at the time when the calculation process of FIG.
May be set.

Second Embodiment FIG. 6 shows the configuration of a scanning multiple exposure apparatus according to a second embodiment of the present invention. The device shown in the figure is different from the device shown in FIG. 1 in that the polarizing beam splitter 2 is replaced by a half mirror 20, and a dimming means 16 capable of continuously changing the transmittance in the optical path of the second illumination system is added. is there. As the dimming means 16, a continuous ND filter whose transmittance continuously changes is used.

FIG. 7 shows an exposure condition setting process in the apparatus shown in FIG. In the process of FIG. 7, the processes of steps S1 to S5 are performed in exactly the same manner as the processes of steps S1 to S5 in FIG. As a result of the determination in step S4, F
If req1 is not equal to Freq2, the magnitude of Freq1 and Freq2 is determined in step S11. If Freq1 is larger, continuous ND filter 16
Is set to Freq2 / Freq1, the transmission frequency Freq of the pulse light source 1 is set to Freq1,
The number of the ND filter used in each illumination system is also set to i and j. On the other hand, if Freq2 is larger, the transmittance of the continuous ND filter 16 is set to (Freq2
× Nd2 [j]) / (Freq1 × Nd2 [j-1])
, The ND filter of the first illumination system has the number i, and the ND filter of the second illumination system has the number Nd2 [j-1] that is one step larger than the calculated number j. After setting or switching to j−1, the pulse light source 1
Is set to Freq1.

Third Embodiment FIG. 8 shows the configuration of a static multiple exposure apparatus according to a third embodiment of the present invention. In the figure, 1 is a light source, for example, KrF
It is a pulse light source such as an excimer laser. 2 is a polarization beam splitter, 3 and 4 are dimming filters, 5 and 7 are half mirrors, 6 and 8 are light quantity sensors, 9 and 10 are illumination optical systems, 11 and 12 are reticles, 13 is a beam splitter,
14 is a projection lens, and 15 is a wafer. The beam splitter 13 converts the pattern images of the reticles 11 and 12 into two adjacent ones on a wafer 15 via a projection lens 14.
This is for projecting to one shot position. FIG.
In the apparatus described above, the pattern images of the reticles 11 and 12 are exposed on the two shots by step-and-repeat in which the pulse light source 1 emits light at two adjacent shot positions on the wafer 15 while moving the wafer 15 stepwise. Therefore, for example, if the exposure is performed while shifting one shot at a time in the arrangement direction of the pattern images of the reticles 11 and 12, the pattern image of the reticle 11 and the pattern image of the reticle 12 are superimposed on each shot excluding the shots at both ends by two exposures. (Double exposure) and two reticle patterns can be simultaneously exposed to one shot. Note that the reticle stage also has a mechanism for moving in the Z direction (a direction parallel to the optical axis) to correct the focus difference between the reticles 11 and 12.

The device shown in FIG. 8 is different from a conventional so-called stepper.
A polarizing beam splitter for simultaneously using two reticles and providing an illumination system and a reticle stage corresponding to each of the two reticles, so that a light beam emitted from the light source 1 is split into two illumination systems. 2 and 2
Light passing through two illumination systems and a reticle
4 is basically configured and operates in the same manner as a conventional stepper, except that a beam splitter 13 for guiding the light to the light source 4 is provided, and that an exposure condition can be set for each illumination system. .

In the apparatus shown in FIG. 8, a fine pattern such as a phase shift pattern (hereinafter referred to as a fine pattern) and a pattern having a desired minimum line width (hereinafter referred to as a rough pattern) are double-exposed to the same shot. Thus, a fine pattern having a minimum line width of, for example, 0.1 μm determined by the minimum line width of the rough pattern can be formed.

Hereinafter, a method of setting exposure conditions for reticles 11 and 12 will be described with reference to FIGS. Here, the exposure amount Dose1 of the reticle 11 is equal to or more than the exposure amount Dose2 of the reticle 12 (Dose1 ≧ Dose2), and the transmittance is discrete by a plurality of ND filters similar to those in FIG. The case where the switching is performed will be described.

Referring to FIG. 9, the exposure condition setting process is started, and when the target light amounts (Dose1, Dose2) are input, preferred exposure conditions are calculated for each illumination system. FIG.
The details of the exposure condition calculation process are shown in FIG. The number of times of pulse emission for exposing one shot is finer as the number increases, so that the minimum number of oscillation pulses (number of times of emission) N _MIN is experimentally or theoretically determined at the time of design from the viewpoint of exposure accuracy. .

In the exposure condition calculating process shown in FIG. 10, first, the ND of the transmittance Nd [i] for one illumination system (here, the first illumination system for illuminating the reticle 11) is used.
Number of oscillation pulses NTemp = Dose / (PlsDose × Nd) for performing optimal exposure using a filter
[I]) is calculated. Here, PlsDose is a nominal light emission amount per pulse, and the ND filter starts from the one with the maximum transmittance (i = 1). Calculated NT
If em is equal to or more than the minimum oscillation pulse number N _MIN , this N
Temp is calculated as the calculated value (N) of the number of oscillation pulses of the first illumination system.
Determined as 1). ND used in the first illumination system
The filter number is also set to i at that time. If the minimum oscillation pulse number N _MIN has not been reached, the calculation of the oscillation pulse number NTemp and the comparison with the minimum oscillation pulse number N _MIN are performed for the ND filter having the next smallest transmittance in the same manner as described above. ND filter with minimum transmittance (i = ND
_{If the} calculated number of oscillation pulses NTemp is less than the minimum number of oscillation pulses N _MIN even if _MAX ) is used, it is determined that there is no solution and the exposure condition calculation process is terminated. After the above-described processing is completed for the first illumination system, NTemp and i are similarly determined for the second illumination system (here, the illumination system for illuminating the reticle 12), and these are determined as N2 and N2, respectively. j. Note that the above-described calculation order is an example, and any one of the first and second illumination systems may be used first. Upon completion of the exposure condition calculation processing for both illumination systems, the process returns to step S32 in FIG.

Referring to FIG. 9, in step S32, if the result of calculating the number of oscillation pulses of at least one of the illumination systems (usually, the second illumination system) is "no solution", an alarm is sounded. The no-solution error process is executed, and the exposure condition setting process ends. Number of oscillation pulses N of both illumination systems
If 1 and N2 have been calculated, then N1 and N2 are compared. If N1 = N2, the number of oscillation pulses suitable for both illumination systems is the same.
Is determined to be N1 = N2.

Normally, in FIGS. 4 and 5, as with the oscillation frequencies Freq1 and Freq2 calculated from the target light amounts Dose1 and Dose2 of the two illumination systems, these coincide with the oscillation pulse numbers N1 and N2. Things are rather rare and in most cases different. When the calculated number of oscillation pulses N1 and N2 are different, the polarization beam splitter 2 is rotated about its normal line to rotate the light reflected by the polarization beam splitter 2 (p-polarized light) and the light transmitted therethrough (p-polarized light). (s-polarized light) is continuously varied. That is, referring to FIG. 9, if the determination in step S34 is not N1 = N2 has its polarization characteristics by rotating the polarization beam splitter _{2, p: s = p 0} × Dose1 / Nd1 [i] / Pls
Dose1: s ₀ × Dose2 / Nd2 [j] / Pls
Set to Dose2. Then, the number N of oscillation pulses of the pulse light source 1 is set to (Dose1 × p ₀ ) / (PlsDose1
× p). Here, p ₀ : s ₀ is a ratio between p-polarized light and s-polarized light, which is a prerequisite for calculating the above N1 and N2, and it is assumed that p ₀ + s ₀ = p + s = 100. s
₀ : p ₀ is set to, for example, 50:50.

Fourth Embodiment FIG. 11 shows the configuration of a static multiple exposure apparatus according to a fourth embodiment of the present invention. The device shown in the figure is different from the device shown in FIG. 8 in that the polarization beam splitter 2 is replaced with a half mirror 20.
A light reducing means 16 capable of continuously changing the transmittance is provided in the optical path of the second illumination system. As the dimming means 16, a continuous ND filter whose transmittance continuously changes is used.

FIG. 12 shows an exposure condition setting process in the apparatus shown in FIG. In the process of FIG.
The processing in S35 is performed in exactly the same manner as the processing in steps S31 to S35 in FIG. If the result of determination in step S34 is that N1 is not equal to N2, in step S41, the transmittance of the continuous ND filter 16 is set to (PlsD
oose1 × Dose2 × Nd1 [i]) / (PlsDo
se2 × Dose12 × Nd2 [j]), and set the number of oscillation pulses of the pulse light source 1 to N = Dose1 / (PlsD).
(ose1 × Nd1 [i]), and the numbers of the ND filters used in the respective illumination systems are also set to i and j.

Fifth Embodiment FIG. 13 shows the configuration of a static multiple exposure apparatus according to a fifth embodiment of the present invention. The device shown in the figure is different from the device shown in FIG. 8 in that the polarization beam splitter 2 is replaced with a half mirror 20.
A shutter 2 is provided in each of the optical paths of the first and second illumination systems.
1 and 22 are arranged.

FIG. 14 shows an exposure condition setting process in the apparatus shown in FIG. In the process of FIG.
The processing in S35 is performed in exactly the same manner as the processing in steps S31 to S35 in FIG. If the result of determination in step S34 is not N1 = N2, in step S51, the number of oscillation pulses of the pulse light source 1 is set to the larger one of the calculated number of oscillation pulses N1 and N2. By driving the exposure shutter 21 or 22 of the illumination system in which the smaller number of oscillation pulses is designated, the number of oscillation pulses N1 and N
The pulse light of the difference number of 2 is shielded. For example, the oscillation frequency of the pulse light source 1 is kept constant, and the exposure shutter is opened for a time corresponding to the smaller number of oscillation pulses during the generation period of the larger number of oscillation pulses.

Embodiment of Device Production Method Next, an embodiment of a device production method using the above-described projection exposure apparatus or method will be described. FIG. 16 shows a micro device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel,
2 shows a flow of manufacturing a CCD, a thin-film magnetic head, a micromachine, and the like. In step 1 (circuit design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. on the other hand,
In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 17 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed on the wafer by exposure using the above-described exposure apparatus or method. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the production method of this embodiment, it is possible to produce a highly integrated device which was conventionally difficult to produce at low cost.

[0037]

As described above, according to the present invention, since a plurality of patterns can be exposed substantially simultaneously using a single exposure light source, the number of exposures can be reduced and the throughput can be improved. Can be. In addition, even when a plurality of types of patterns having different exposure conditions are exposed to a plurality of shots substantially simultaneously, it is not necessary to change the setting of the illumination system for each shot or for each exposure. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a scanning multiple exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an exposure amount setting process in the apparatus of FIG.

FIG. 3 is a flowchart showing details of an exposure condition calculation process in the process of FIG. 2;

FIG. 4 is a graph showing an example of an exposure condition calculated in the process of FIG.

FIG. 5 is a graph showing another example of the exposure condition calculated in the process of FIG.

FIG. 6 is a configuration diagram of a scanning multiple exposure apparatus according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing an exposure amount setting process in the apparatus of FIG. 6;

FIG. 8 is a configuration diagram of a static multiple exposure apparatus according to a third embodiment of the present invention.

FIG. 9 is a flowchart showing an exposure amount setting process in the apparatus of FIG. 8;

FIG. 10 is a flowchart showing details of an exposure condition calculation process in the process of FIG. 9;

FIG. 11 is a configuration diagram of a static multiple exposure apparatus according to a fourth embodiment of the present invention.

FIG. 12 is a flowchart showing an exposure amount setting process in the apparatus of FIG. 11;

FIG. 13 is a configuration diagram of a static multiple exposure apparatus according to a fifth embodiment of the present invention.

FIG. 14 is a flowchart showing an exposure amount setting process in the apparatus of FIG.

FIG. 15 is a graph showing an exposure amount setting state in the scanning exposure apparatus.

FIG. 16 is a diagram showing a flow of manufacturing a micro device.

FIG. 17 is a diagram showing a detailed flow of the wafer process in FIG. 16;

[Explanation of symbols]

1: light source, 2: polarizing beam splitter, 3, 4: discrete variable type neutral density filter, 5, 7: half mirror, 6,
8: light intensity sensor, 9, 10: illumination optical system, 11, 12:
Reticles, 13, 20: beam splitter, 14: projection lens, 15: wafer, 16: continuously variable neutral density filter, 21, 22: exposure shutter.

Claims (15)

[Claims] When a plurality of patterns are exposed on a substrate to be exposed substantially simultaneously, a light beam emitted from a single exposure light source is divided, each pattern is illuminated with a separate light beam, and an optical path of each of the divided light beams is provided. An exposure method, wherein a desired exposure condition is set for each light beam by an illumination system disposed therein. 2. The method according to claim 1, wherein the exposure condition includes an exposure amount, and a transmittance of the dimming unit in which a transmittance changes discretely for each of the divided light fluxes and an output light amount of the light source according to the desired exposure amount. Calculate, set the transmittance of each dimming means, set the division ratio to each light flux to a value corresponding to the calculated ratio of the emitted light amount, and set the emission light amount value of the light source to the division ratio 2. The exposure method according to claim 1, wherein a change in the amount of light from each of the luminous fluxes due to the change in the amount of light from the calculated outgoing light amount is set to a value for correcting the amount of change. 3. The exposure condition includes an exposure amount, and the transmittance of the dimming means whose transmittance changes discretely for each of the divided light fluxes and the output light amount of the light source are determined according to the desired exposure amount. The transmittance is set for each of the dimming means, the emission light amount of the light source is set to the emission light amount calculated for one of the divided light beams, and for each light beam other than the one split light beam. Is provided with a dimming means whose transmittance continuously changes in the optical path for each light flux, and the transmittance of the continuous dimming means is determined by the amount of emitted light calculated for each light flux and the emission set by the light source. 2. The exposure method according to claim 1, wherein the setting is made so as to correct the difference from the light amount. 4. A method according to claim 1, wherein a pulsed light source is used as the light source, and the exposure is performed by synchronously scanning one or more originals on which the plurality of patterns are formed and the substrate to be exposed relative to a projection optical system. 4. The projection exposure method according to claim 2, wherein an oscillation frequency of the light source is calculated as the amount of emitted light, the method being a scanning projection exposure method for exposing images of the plurality of patterns on a substrate. 5. A method according to claim 1, wherein a pulse light source is used as the light source, the one or more originals on which the plurality of patterns are formed are stopped, and the plurality of the plurality of patterns are formed on the exposed substrate by sequentially moving the exposed substrate. 4. The projection exposure method according to claim 2, wherein a static projection exposure method for performing step-and-repeat exposure of a pattern image, wherein the number of oscillations of the light source is calculated as the amount of emitted light. 6. The exposure method according to claim 1, wherein at least one of the plurality of patterns is a type of pattern having different exposure conditions from other patterns. 7. An exposure apparatus for exposing a plurality of patterns onto a substrate to be exposed substantially simultaneously, comprising: means for dividing a light beam emitted from a single exposure light source into a plurality of light beams; And an illumination system for setting the exposure conditions. 8. The illumination system according to claim 1, wherein
A dimming means whose transmittance changes discretely, and a means for calculating the transmissivity of the dimming means and the emission light amount of the light source according to the desired exposure amount, and according to all the calculated values 8. An exposure apparatus according to claim 7, further comprising means for setting the amount of light emitted from said single light source and the transmittance of each light reducing means. 9. The transmittance setting means for setting a transmittance calculated for each of the dimming means, and a dividing ratio for each light flux according to a ratio of the calculated emitted light amount. And an emission light amount setting for setting the emission light amount of the light source to a value that compensates for a change from the calculated emission light amount of the light amount for each light beam due to a change in the division ratio. And means.
Exposure apparatus according to the above. 10. The continuous type dimming means which is arranged in at least the optical path of each light beam other than the main light beam among the divided light beams and whose transmittance continuously changes, and wherein each of the discrete type light reducing devices is provided. Discrete transmittance setting means for setting the transmittance calculated for each light means, emission light quantity setting means for setting the emission light quantity of the light source to the emission light quantity calculated for the main light flux, and each of the light fluxes other than the main light flux 9. A light amount compensating means for varying the transmittance of the continuous type dimming means so as to compensate for a difference between the outgoing light amount calculated for the light beam and the outgoing light amount calculated for the main light beam. Exposure apparatus according to the above. 11. The exposure apparatus according to claim 1, wherein the light source is a pulse light source, and the exposure is performed by synchronously scanning one or more masters on which the plurality of patterns are formed and the substrate to be exposed relative to a projection optical system. 11. The exposure apparatus according to claim 9, wherein the scanning projection exposure apparatus exposes the images of the plurality of patterns on a substrate, wherein the emission light amount setting unit sets an oscillation frequency of the light source. . 12. The method according to claim 11, wherein the light source is a pulsed light source, and the one or more originals on which the plurality of patterns are formed are stopped, and the images of the plurality of patterns are formed by sequentially moving the substrate to be exposed. 11. The projection exposure apparatus according to claim 9, wherein the projection exposure apparatus is a static projection exposure apparatus that performs step-and-repeat exposure on an exposure substrate, wherein the number of oscillations of the light source is calculated as the amount of emitted light. 13. The method according to claim 13, wherein the plurality of patterns are at least one.
13. The exposure method according to claim 7, wherein one of the patterns is a pattern of a type having different exposure conditions from the other patterns. 14. A device manufacturing method, wherein a device is manufactured using the exposure method according to claim 1 or the exposure apparatus according to claim 7. 15. A device manufactured by the device manufacturing method according to claim 14.