WO2005055295A1

WO2005055295A1 - Exposure method and system, and device producing method

Info

Publication number: WO2005055295A1
Application number: PCT/JP2004/017817
Authority: WO
Inventors: Taro Ogata; Takehito Kudo
Original assignee: Nikon Corporation
Priority date: 2003-12-03
Filing date: 2004-11-30
Publication date: 2005-06-16

Abstract

An exposure method and a system therefor able to regulate characteristics regarding a pitch dependency by the line width of a projection image or OPE (Optical Proximity Effect) characteristics to specified states. Pitch dependency characteristics of the line width of a projection image (OPE characteristics) (C17) at a first exposure system and an OPE characteristics (C24) at a second exposure system are respectively determined by simulation. Exposure conditions (numerial aperture of a projection optical system, coherence factor of a lighting optical system, a lighting ring ratio during ring lighting by the lighting optical system, exposure quantity, etc.) at the second exposure system are regulated so that line widths in terms of two OPE characteristics (C17, C24) agree within a specified allowable range at three pattern pitches (p1, p2, p3).

Description

Specification

Exposure method and apparatus, and device manufacturing method

Technical field

The present invention relates to a lithography apparatus for manufacturing a device such as a semiconductor integrated circuit or a liquid crystal display element, which is used for transferring a mask pattern onto a substrate via a projection optical system. The present invention is suitable for use in the technology, particularly when adjusting the characteristic relating to the pitch dependency of the line width of the projected image or the characteristic of OPE (Optical Proximity Effect) which is an optical proximity effect of the projected image.

Background art

[0002] For example, during a lithographic process for manufacturing a semiconductor integrated circuit, a pattern of a reticle (or a photomask or the like) as a mask is coated with a photoresist as a substrate (sensitive object) via a projection optical system. A batch exposure type such as a stepper and a scanning exposure type projection exposure apparatus such as a scanning stepper are used to transfer the image onto each shot area of a wafer (or a glass plate or the like). With the further miniaturization of integrated circuits in recent years, the demand for uniformity of the line width of a transferred pattern in a projection exposure apparatus is increasing.

[0003] Regarding the "uniformity of line width", a plurality of line "and" space patterns formed by arranging line patterns of the same line width on a reticle at different pitches from each other are transmitted through a projection optical system of a projection exposure apparatus. Consider the case where the image is transferred onto a wafer. In this case, even if the projection optical system has no aberration, each line pattern of a plurality of resist patterns formed on the wafer after development by OPE (Optical Proximity Effect) which is an optical proximity effect of the projected image. The line width of the (or space pattern) changes depending on the pitch. Such pitch dependence of the line width of the transferred pattern (or projected image) is called “OPE characteristic”. Usually, a certain degree of aberration remains in the projection optical system of the projection exposure apparatus, and the OPE characteristic changes due to the remaining aberration.

[0004] Furthermore, the ideal light amount distribution of exposure light (exposure beam) on the pupil plane of the illumination optical system is a uniform distribution within a circular area for normal illumination, and an annular area for annular illumination. It is a uniform distribution within. In fact, the light intensity distribution of the exposure light There is a certain degree of unevenness (, so-called brightness unevenness) for each device, and the OPE characteristics also change due to the uneven brightness. The また characteristic also changes depending on the exposure conditions such as the numerical aperture (NA) of the projection optical system and the coherence factor (σ value) of the illumination optical system. Therefore, an actual projection exposure apparatus has its own ΟΡΕ characteristic depending on the aberration of the projection optical system, the uneven brightness of the exposure light, and the exposure conditions.

[0005] Conventionally, in order to correct the pitch dependency of the line width due to the ΟΡΕ characteristic, the characteristic of a projection exposure apparatus is measured in advance, and when a reticle is made, the line of the projected image is different due to the difference in pitch. To prevent variations in width, the line width of each pattern was corrected by an offset that offsets the ΟΡΕ characteristic.

In addition, as a conventional method for correcting the pitch dependency of the line width, attention is paid to the periodic pattern of fine pitch and the pattern of the isolated line, and the line width of the projected image of the periodic pattern and the projection of the isolated line pattern are taken. There is known a method of adjusting the numerical aperture of a projection optical system, the coherence factor of an illumination optical system, and the like so that the difference (bias) from the line width of an image falls within a predetermined allowable range (for example, see Patent Document 1). See.)

Patent Document 1: U.S. Patent Application Publication No. 2001Z0026448A1

[0006] Among the conventional techniques as described above, the method of correcting the line width of each pattern at the time of producing a reticle is not limited to a method in which the produced reticle can be used in a specific projection exposure apparatus. There is a disadvantage that the projection exposure apparatus may not be used. Therefore, when another projection exposure apparatus is used, a new reticle must be manufactured in accordance with the ΟΡΕ characteristics of the projection exposure apparatus, which is one of the factors that increase the manufacturing cost of semiconductor integrated circuits and the like. Had become.

On the other hand, a conventional method of adjusting the numerical aperture of a projection optical system or the like so that the difference between the line width of the projected image of the periodic pattern and the line width of the projected image of the isolated line pattern falls within a predetermined allowable range. In this case, the ΟΡΕ characteristic of the first projection exposure apparatus adjusted by this method and the ΟΡΕ characteristic of another second projection exposure apparatus were not necessarily matched. That is, due to the ΟΡΕcharacteristics of the first and second projection exposure apparatuses, the absolute value of the line width of the projected image of the periodic pattern and the isolated line is different from each other, and the absolute value of the projected image of the isolated line is different from that of the periodic pattern and the isolated line. ΟΡΕ characteristics at pitch differed from each other. Therefore, its first projection dew The reticle produced by correcting the OPE characteristics for the optical device was too powerful to be used in the second projection exposure apparatus.

[0008] Conventionally, the purpose is to match the line width of the projected image between the periodic pattern and the isolated pattern, and to adjust the OPE characteristics within a predetermined pitch range as a whole to a predetermined state. There was no. In the future, as the miniaturization and high integration of integrated circuits and the like progress further, it is expected that it is required to further increase the line width uniformity within a predetermined pitch range as a whole.

Furthermore, in order to obtain higher linewidth uniformity as semiconductor integrated circuits become finer, changes in OPE characteristics due to uneven brightness of exposure light can be corrected with high accuracy for each projection exposure apparatus. Is required.

Disclosure of the invention

In view of the above, the present invention provides an exposure technique and a device manufacturing technique capable of adjusting the characteristic relating to the pitch dependency of the line width of a projected image or the characteristic of an OPE for each exposure apparatus. Aim.

[0010] Furthermore, the present invention is designed so that the characteristics relating to the pitch dependency of the line width of the projected image or the characteristics of the OPE can be matched in a predetermined state within a predetermined pitch range or between a plurality of exposure apparatuses. A second object is to provide an exposure technology and a device manufacturing technology that can be adjusted to a desired level.

Further, the present invention provides an exposure technique and a device capable of correcting, for each exposure apparatus, a characteristic relating to a pitch dependency of a line width of a projection image or an OPE characteristic caused by unevenness in a light amount distribution of an exposure beam on a pupil plane of an illumination optical system. The third purpose is to provide manufacturing technology.

[0011] The following reference numerals in parentheses attached to the respective elements of the present invention correspond to the configuration of an embodiment of the present invention described later. However, each reference sign is merely an example of that element and does not limit each element to the configuration of the embodiment.

The first exposure method according to the present invention illuminates a first object (R) with an exposure beam from an illumination optical system (3), and irradiates the first object (R) with the exposure beam via the first object and a projection optical system (PL). In the exposure method for exposing two objects (W), the second object is adjusted in order to adjust each of the line widths of a plurality of mutually different patterns projected through the projection optical system to a predetermined state. This is to change the exposure condition for exposure.

According to the present invention, by adjusting the line widths of the projection images of a plurality of patterns to a predetermined state by changing the exposure conditions, the characteristic relating to the pitch dependency of the line widths of the projection images is obtained. In addition, the characteristics of OPE (Optical Proximity Effect) can be adjusted for each exposure apparatus. This makes it possible to use, for example, a mask whose OPE characteristics have been corrected in common by a plurality of exposure apparatuses.

[0013] In the present invention, the line widths of three or more different patterns projected from the projection optical system through the projection optical system may be adjusted to corresponding reference values.

In this case, the three or more types of patterns are, for example, three or more patterns having different pitches from each other. At this time, the three or more patterns include, for example, a pattern having a minimum pitch, a pattern having a maximum pitch, and a pattern having an intermediate pitch between the pattern having the minimum pitch and the pattern having the maximum pitch. At this time, within a predetermined pitch range between the pattern of the minimum pitch including the pattern of the intermediate pitch and the pattern of the maximum pitch, the characteristic relating to the pitch dependence of the line width of the projected image and the characteristic of the OPE Can be adjusted to a predetermined state determined by the reference value. Further, by setting the reference value to a value corresponding to, for example, a mask whose OPE characteristics have been corrected, the mask can be commonly used by a plurality of exposure apparatuses. Further, by using the reference value as the line width measured by another exposure apparatus, it is possible to perform matching between a plurality of exposure apparatuses with respect to the pitch dependency of the line width of the projected image.

Further, in the present invention, the change in the line width of the projected image caused by the unevenness in the light amount distribution of the exposure beam on the pupil plane of the illumination optical system or a conjugate plane with this plane is brought into a predetermined state. It may be adjusted. This makes it possible to correct, for each exposure apparatus, the characteristic relating to the pitch dependency of the line width of the projected image or the characteristic of the OPE caused by the unevenness in the light amount distribution of the exposure beam on the pupil plane of the illumination optical system.

In this case, the light amount distribution is such that, for example, the light amount of the exposure beam is substantially uniformly distributed in a circular area, an annular area, or a plurality of eccentric areas. As a result, when using normal illumination, annular illumination, or so-called modified illumination (dipole, quadrupole illumination, etc.), the OPE characteristics are set to the same characteristics as when illumination is performed with an ideal light amount distribution. exposure It can be performed.

In the above-described present invention, as an example, the exposure conditions are plural, and the exposure conditions are adjusted within a range that does not substantially affect the imaging characteristics of the projection optical system. Thereby, for example, the OPE characteristic without lowering the resolution of the projected image can be adjusted to a predetermined state.

Also, as an example, the plurality of patterns are three or more types of patterns, and three or more types of exposure conditions are used in order to adjust the line widths of the projected images of the three or more types of patterns to the corresponding reference values. May be set. In this way, as the number of exposure conditions to be set is increased, it becomes easy to adjust the line width of the projected image with three or more types of patterns, and the type of pattern to be adjusted (for example, the number of pitches) ) Can be increased.

Before changing the exposure conditions, the line widths of the plurality of patterns projected through the projection optical system may be obtained! By using the value obtained by optical simulation or actual measurement for the line width of the projected image, the pitch dependence characteristic of the projected image line width can be adjusted with higher accuracy.

Next, a second exposure method according to the present invention includes a first exposure apparatus (1A) for exposing an object via a first projection optical system (PLA) and a second exposure optical system (PLB). According to an exposure method using a second exposure apparatus (1B) for exposing an object, a line width of a projected image of three or more different patterns through the second projection optical system is different from each other. The exposure conditions of the second exposure apparatus are set in order to make each of them correspond to the line width of the projected image via the first projection optical system.

According to the present invention, it is possible to match between the first and second exposure apparatuses with respect to the characteristic relating to the pitch dependency of the line width of the projected image, and further to the characteristic of the OPE. Therefore, for example, it is possible to commonly use a mask whose OPE characteristics have been corrected.

Also in the present invention, in order to match the line widths of the three or more types of patterns projected through the second projection optical system with the line widths of the projection images transmitted through the first projection optical system, respectively. Alternatively, three or more exposure conditions for the second exposure apparatus may be set.

Next, an exposure apparatus according to the present invention provides an illumination optical system (3) for illuminating a first object (R) with an exposure beam, and projects an image of the first object onto a second object (W). With projection optics (PL) Control for changing the exposure condition for exposing the second object in order to adjust each of the line widths of a plurality of different patterns projected through the projection optical system to a predetermined state. Device (41).

According to the present invention, by adjusting the line widths of the projection images of the plurality of patterns to predetermined states by changing the exposure conditions, the characteristic relating to the pitch dependency of the line widths of the projection images is obtained. In addition, the characteristics of OPE (Optical Proximity Effect) can be adjusted for each exposure apparatus.

In the present invention, in order to adjust the line widths of three or more different patterns projected from the projection optical system through the projection optical system to the corresponding reference values, the control device may change the exposure condition. Good. In this case, the three or more types of patterns include, for example, a pattern having a minimum pitch, a pattern having a maximum pitch, and a pattern having an intermediate pitch between the pattern having the minimum pitch and the pattern having the maximum pitch. At this time, within a predetermined pitch range between the minimum pitch pattern including the intermediate pitch pattern and the maximum pitch pattern, the characteristic relating to the pitch dependency of the line width of the projected image, and eventually the OPE characteristic, is changed to a predetermined state. Can be adjusted.

[0021] Further, in order to adjust the change in the line width of the projected image caused by unevenness in the light amount distribution of the exposure beam on the pupil plane of the illumination optical system or a conjugate plane with the plane, to a predetermined state. Alternatively, the control device may change the exposure condition. This makes it possible to correct the characteristic relating to the pitch dependency of the line width of the projected image or the characteristic of the OPE due to the unevenness in the light amount distribution of the exposure beam on the pupil plane of the illumination optical system for each exposure apparatus.

The light amount distribution is, for example, a state in which the light amount of the exposure beam is substantially uniformly distributed in a circular area, an annular area, or a plurality of eccentric areas.

In the present invention, as an example, a plurality of exposure conditions are set, and the exposure conditions are adjusted within a range that does not substantially affect the imaging characteristics of the projection optical system. In order to match the line widths of the projected images of the three or more patterns with the corresponding reference values, the control device sets three or more exposure conditions. May be set. [0022] The image processing apparatus may further include an arithmetic unit (41a) or an aerial image measurement system (29) for obtaining line width information of the aerial image of the three or more types of patterns via the projection optical system. As a result, the line widths of the projected images of these patterns can be efficiently obtained only by optical simulation without performing test printing or by only measuring the aerial image.

One example of the reference value is a line width of a projected image of the three or more types of patterns projected via the projection optical system of another exposure apparatus. This makes it possible to match between the plurality of exposure apparatuses with respect to the pitch dependency of the line width of the projected image.

Further, another example of the reference value is, for example, a value corresponding to a mask whose OPE characteristic has been corrected. Thus, the mask can be used in common by a plurality of exposure apparatuses.

In the exposure method and apparatus of the present invention, the three or more types of patterns include, for example, first, second, and third periodic patterns having gradually different pitches. In this case, the first, second, and third periodic patterns are further regarded as a fine pitch (pi) pattern, a larger pitch (p2) intermediate pitch pattern, and a substantially isolated pattern, respectively. A coarse pitch (p3) pattern that can be used. Thus, the characteristics relating to the pitch dependency of the line width of the projected image can be adjusted in a predetermined state within a wide pitch range.

In the exposure method and apparatus of the present invention, the exposure conditions set include, for example, a numerical aperture of the projection optical system, a coherence factor of the illumination optical system, and an illumination condition of the illumination optical system. At least one of the illumination zone ratio of the annular illumination, the wavelength of the exposure beam, the half width of the wavelength of the exposure beam, the exposure amount of the exposure beam, and the type of photosensitive material on the second object. is there.

In this case, if the line width of the projected image of the three different patterns (for example, three patterns with different pitches) through the projection optical system is to be adjusted to the corresponding reference values, the exposure conditions are as follows. The numerical aperture of the projection optical system, the coherence factor of the illumination optical system, and the illumination annular ratio may be used when the illumination optical system performs annular illumination. Further, under these conditions, the exposure amount of the exposure beam may be adjusted.

[0025] Further, the first device manufacturing method according to the present invention is a device manufacturing method including a lithographic process, wherein the exposure conditions set by the exposure method of the present invention during the lithographic process. Is used to transfer the pattern (R) onto the photoreceptor (W).

A second device manufacturing method according to the present invention is a device manufacturing method including a lithographic process, wherein the pattern (R) is transferred onto the photoreceptor (W) by the exposure apparatus of the present invention during the lithographic process. It is. According to these device manufacturing methods, by applying the present invention, a mask with corrected OPE characteristics can be commonly used in a plurality of exposure apparatuses at the time of exposure, so that manufacturing costs can be reduced.

According to the present invention, in order to adjust each of the line widths of the projection images of a plurality of patterns different from each other to a predetermined state, the pitch condition of the projection image line width is changed by changing the exposure condition. Characteristics or OPE characteristics can be adjusted for each exposure apparatus. Further, in the present invention, when the exposure condition is changed in order to match the line widths of the projected images of three or more different patterns to the corresponding reference values, the pitch dependency of the line widths of the projected images is changed. The characteristic relating to the performance or the characteristic of the OPE can be adjusted to a predetermined state within a predetermined pitch range (a range between the pattern of the minimum pitch and the pattern of the maximum pitch).

Further, in the present invention, a change in the line width of the projected image caused by unevenness in the light amount distribution of the exposure beam on the pupil plane of the illumination optical system or a conjugate plane with this plane is adjusted to a predetermined state. In order to change the exposure condition, the characteristic relating to the pitch dependency of the line width of the projected image or the characteristic of the OPE caused by the unevenness of the light amount distribution can be corrected for each exposure apparatus.

Further, in the present invention, when the exposure conditions are set so that the line widths of the projected images of three or more different patterns are different from the line widths of the projected images obtained by different exposure apparatuses, The characteristics relating to the pitch dependency of the line width of the projected image or the characteristics of the OPE can be adjusted so that matching can be achieved between a plurality of exposure devices.

Brief Description of Drawings

FIG. 1 is a perspective view showing a projection exposure apparatus used in an embodiment of the present invention.

FIG. 2 is an enlarged view showing an example of an OPE characteristic evaluation pattern.

FIG. 3 is an enlarged view showing a projected image of the pattern of FIG. 2 via a projection optical system.

FIG. 4 shows a case where the projection optical system has no aberration in the first embodiment of the present invention. FIG. 9 is a diagram illustrating an example of a simulation result of OPE characteristics of the projection exposure apparatus.

[5] FIG. 5 is a diagram showing the change in OPE characteristics when the numerical aperture (projection NA) of the projection optical system is also changed in the state force in FIG.

[FIG. 6] A diagram showing a change in OPE characteristics when the lighting sigma is changed from the state in FIG. 4. [7] A diagram showing changes in OPE characteristics when the state force in Fig. 4 is changed. It is a figure.

[8] Fig. 8 is a diagram showing changes in OPE characteristics when the projection NA, illumination sigma, and illumination ring zone ratio are each changed by 0.01.

[9] FIG. 9 is a diagram showing a simulation result of OPE characteristics of the projection exposure apparatus when the projection optical system has an aberration.

[10] FIG. 10 is a diagram showing an example of adjusting the OPE characteristics using the projection NA in the first embodiment of the present invention.

[11] FIG. 11 is a diagram showing an example in which the OPE characteristic is adjusted using both the projection NA and the illumination sigma in the first embodiment of the present invention.

[12] FIG. 12 is a diagram illustrating an example of a simulation result of the OPE characteristic of the projection exposure apparatus when the projection optical system has no aberration in the second embodiment of the present invention.

[13] Fig. 13 is a diagram illustrating an example of a luminance distribution (light amount distribution) in a pupil plane during annular illumination.

[FIG. 14] OP obtained by simulation based on the luminance distribution in the pupil plane of FIG. 13

FIG. 9 is a view showing an E characteristic.

[15] FIG. 15 is a diagram showing changes in OPE characteristics when the projection NA is changed when there is a luminance distribution with a tendency to be convex in the middle.

[16] FIG. 16 is a diagram showing changes in OPE characteristics when the illumination sigma is changed when there is a luminance distribution with a tendency to be convex in the middle.

[17] FIG. 17 is a diagram showing changes in OPE characteristics when the illumination ring zone ratio is changed in the case where there is a luminance distribution with a tendency to be convex toward the center.

[18] Fig. 18 is a diagram showing the rate of change of the OPE characteristic when the projection NA, the illumination sigma, and the illumination ring zone ratio are each changed by 0.01 in the case where there is a luminance distribution with a tendency to be convex in the middle. FIG. 19 is a diagram showing an example of OPE characteristics optimized by adjusting exposure conditions in the case where there is a luminance distribution having a convexity in the second embodiment of the present invention.

FIG. 20 is a diagram showing a change in OPE characteristics when the projection NA is changed when there is a luminance distribution with a decreasing tendency.

FIG. 21 is a diagram showing a change in OPE characteristics when the illumination sigma is changed when there is a luminance distribution with a decreasing tendency.

FIG. 22 is a diagram showing changes in OPE characteristics when the illumination ring zone ratio is changed when there is a luminance distribution with a decreasing tendency.

FIG. 23 is a diagram showing the rate of change of the OPE characteristic when the projection NA, the illumination sigma, and the illumination ring zone ratio are changed by 0.01, respectively, when there is a luminance distribution with a decreasing tendency.

FIG. 24 is a diagram showing an example of OPE characteristics optimized by adjusting exposure conditions in a case where there is a luminance distribution with a decreasing tendency in the second embodiment of the present invention.

FIG. 25 is a perspective view showing an exposure system according to a third embodiment of the present invention.

FIG. 26 is a flowchart showing an example of an operation for matching OPE characteristics of two exposure apparatuses in the third embodiment. Explanation of symbols

[0029] 1A, 1Β ··· Exposure apparatus, 2 ··· Exposure light source, 3 ··· Illumination optical system, 4 ··· Host computer, R, Ml, Μ2 ··· Reticle, W, Wl, W2 "-Ueno, PL, PLA, PLB… Projection optical system, 11 ··· Illumination system aperture stop member, 35 ··· Variable aperture stop, 29… Aerial image measurement system, 41, 41A, 41Β ··· Main control system, 41a… Computer

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment]

Hereinafter, a first preferred embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a scanning exposure type projection exposure apparatus (exposure apparatus) including the scanning stepper of the present embodiment. In FIG. 1, an exposure light source 2 that generates exposure light IL as an exposure beam includes: An ArF excimer laser light source (wavelength 193 nm) is used. The exposure light source is a KrF excimer laser light source (wavelength 248 nm), an F laser light source (

2

Wavelength 157 nm), Kr laser light source (wavelength 146 nm), YAG laser harmonic generation light source, fixed A harmonic generator of a body laser (such as a semiconductor laser) or a mercury lamp can also be used. Further, under the control of the exposure amount control system 43, the exposure light source 2 of the present example controls the wavelength (exposure wavelength) of the exposure light IL (ultraviolet pulse laser light in this example) and the wavelength of the exposure light IL. The half width is configured to be controllable in a predetermined range.

[0031] Exposure light (illumination light for exposure) IL emitted from the exposure light source 2 at the time of exposure passes through the mirror 7, the beam shaping optical system (not shown), the first lens 8A, the mirror 9, and the second lens 8B. Through this, the cross-sectional shape is shaped into a predetermined shape, and the light enters the fly-eye lens 10 as an optical integrator (uniformizer or homogenizer), and the illuminance distribution is made uniform. On the exit surface of the fly-eye lens 10 (pupil surface of the illumination optical system), the light intensity distribution of the exposure light is circular (normal illumination), a plurality of eccentric regions (deformed illumination such as dipole and quadrupole illumination), a ring zone ( Illumination with an aperture stop (σ stop) 13A, 13B, 13C, 13D for setting illumination conditions by setting it to a ring shape or a small circle (small _σ illumination with a small coherence factor (σ value)) A system aperture stop member 11 is rotatably arranged by a drive motor 12. The aperture stop 13C having the annular aperture for annular illumination of this example has a coherence factor (σ value) based on the outer diameter of the aperture and the value of the ratio of the inner diameter to the outer diameter of the aperture. The ratio can be controlled within a predetermined range. Further, even when other aperture stops 13A, 13B, 13D and the like are used, the configuration is such that the coherence factor (σ value) can be adjusted. Main control system 41 consisting of a computer that supervises and controls the operation of the entire system 41 (Control device) 1S The illumination system aperture stop member 11 is rotated via the drive motor 12 to set the illumination conditions, and its coherence factor (σ value) And at the same time, control the illumination zone ratio during zone illumination.

The exposure light IL that has passed through the aperture stop in the illumination system aperture stop member 11 passes through the beam splitter 14 and the relay lens 17A having low reflectance, and passes through the fixed blind 18 ° as a fixed field stop and the movable field stop. Sequentially pass through the movable blind 18B. In this case, the movable blind 18B is arranged on a surface almost conjugate with the pattern surface (reticle surface) of the reticle R as a mask, and the fixed blind 18A is a surface on which the surface force conjugate with the reticle surface is slightly defocused. Placed in! RU

In this embodiment, the illumination system aperture stop member 11 is used to change the illumination condition for the reticle R. The optical optical integrator (fly-eye lens) 10 It is preferable that the intensity distribution of the illumination light or the incident angle range of the illumination light on the incident surface is variable to minimize the loss of light amount due to the change in the illumination conditions described above. For this purpose, instead of or in combination with the illumination system aperture stop member 11, for example, a plurality of diffractive optical elements exchanged and arranged on the optical path of the illumination optical system 3, along the optical axis of the illumination optical system 3 An optical unit including at least one movable prism (for example, a conical prism or a polyhedral prism) and at least one zoom optical system is disposed between the light source 2 and the optical integrator (fly-eye lens) 10. Can be adopted.

[0034] The fixed blind 18A is used to define the illumination area 21R on the reticle surface as a slit-like area elongated in a non-scanning direction orthogonal to the reticle R scanning direction. The movable blind 18B has two pairs of blades that are relatively movable in directions corresponding to the scanning direction and the non-scanning direction of the reticle R, respectively, and is unnecessary at the start and end of scanning exposure for each shot area to be exposed. It is used to close the illuminated area in the scanning direction so that no exposure to the part takes place. The movable blind 18B is also used to define the center and width of the illumination area in the non-scanning direction. The exposure light IL passing through the blinds 18A and 18B passes through the sub-condenser lens 17B, the mirror 19 for bending the optical path, and the main condenser lens 20 to uniformly illuminate the illumination area 21R of the pattern area of the reticle R as a mask. Illuminate with distribution.

On the other hand, the exposure light reflected by the beam splitter 14 is received by an integrator sensor 16 composed of a photoelectric sensor via a condenser lens 15. The detection signal of the integrator sensor 16 is supplied to the exposure control system 43, and the exposure control system 43 uses the detection signal and the beam splitter 14 which has been measured in advance to determine the optical power up to the wafer W as a substrate (sensitive substrate). The exposure energy on the wafer W is calculated indirectly using the transmittance of the system. The exposure control system 43 controls the light emission operation of the exposure light source 2 (emission period, light emission period) based on the integrated value of the calculation result and the control information from the main control system 41 so as to obtain an appropriate exposure amount on the wafer W. It controls the emission frequency, output (energy per pulse), wavelength, half-width of wavelength, etc. Mirrors 7, 9; lenses 8A, 8B; fly-eye lens 10, illumination system aperture stop 11, beam splitter 14, relay lens 17A, blinds 18A, 18B, sub-condenser lens 17B, mirror 19, and main condenser lens 20 The illumination optical system 3 is configured to include this. [0036] Under the exposure light IL, the pattern in the illumination area 21R of the reticle R passes through the projection optical system PL at a projection magnification j8 (j8 is 1Z4, 1Z5, or the like) at a wafer W coated with a photoresist. The light is projected on a slit-like exposure area 21W which is elongated in the non-scanning direction on the upper one shot area SA. The wafer W is a disk-shaped substrate such as a semiconductor (eg, silicon) or SOI (silicon on insulator) having a diameter of about 200 to 300 mm. The pattern surface (reticle surface) of reticle R and the surface (wafer surface) of wafer W correspond to the object plane and image plane of the projection optical system, respectively. Further, reticle R and wafer W can be regarded as a first object and a second object (photoconductor), respectively.

[0037] The projection optical system PL of the present example is a power projection optical system PL. The projection optical system PL has optical axes intersecting each other as disclosed in, for example, US Patent No. 6,496,306. A catadioptric system consisting of multiple optical systems can also be used. Further, a variable aperture stop 35 is arranged on a pupil plane of the projection optical system PL. The main control system 41 is configured to drive the variable aperture stop 35 to control the numerical aperture of the projection optical system PL. Hereinafter, in FIG. 1, the Z axis is taken in parallel with the optical axis AX of the projection optical system PL, and the non-scanning direction orthogonal to the scanning direction of the reticle R and the wafer W during scanning exposure is in a plane perpendicular to the Z axis. The following describes the X axis and the Y axis in the scanning direction.

First, the reticle R is held on a reticle stage (first stage) 22, and the reticle stage 22 moves at a constant speed in the Y direction on the reticle base 23, and moves in the X direction so as to correct a synchronization error. The reticle R is scanned by fine movement in the Y and rotation directions. The position of the reticle stage 22 is measured by a movable mirror (not shown) and a laser interferometer (not shown) provided thereon, and based on the measured values and control information from the main control system 41, the stage drive is performed. The system 42 controls the position and speed of the reticle stage 22 via a drive mechanism (not shown) (such as a linear motor). Above the periphery of reticle R, reticle alignment microscopes 34A and 34B for detecting the positions of alignment marks 32A and 32B near pattern area 31 on reticle R via mirrors 33A and the like. Arranged!

On the other hand, the wafer W is held on a wafer stage 27 via a wafer holder 24, and the wafer stage 27 moves at a constant speed in the Y direction on the wafer base 28, and moves in steps in the X and Y directions. It has a moving XY stage 26 and a Z tilt stage 25. Z The tilt stage 25 performs focusing and leveling of the wafer W based on a measurement value of the position of the wafer W in the Z direction by an autofocus sensor (not shown). The position of the wafer stage 27 in the XY plane and the rotation angles around the X, Y, and Z axes are measured by a laser interferometer (not shown), and the measured values and the control information from the main control system 41 are used. Based on this, the stage drive system 42 controls the operation of the wafer stage 27 via a drive mechanism (such as a linear motor) not shown.

Further, near the wafer W on the wafer stage 27, an aerial image measurement system 29 having slit-shaped openings 30A and 30B formed along the Y direction and the X direction, respectively, is installed. . The surface on which the openings 30A and 30B are formed is arranged so as to be at the same height as the wafer surface, and photoelectric sensors are arranged on the bottom surfaces of the openings 30A and 30B via condensing optical systems, respectively. The detection signal of the sensor is supplied to a signal processing unit in the main control system 41. In this example, the wafer stage 27 is driven in the X direction (or Y direction) to scan the projected image of the pattern of the reticle R through the opening 30A (or 30B) while detecting the detection signal of the photoelectric sensor. The line width of the projected image can be detected at the stage of the aerial image.

It should be noted that an irradiation amount monitor (not shown) having a light receiving surface larger than the exposure area 21 W is also arranged on the wafer stage 27, and this detection signal is supplied to the exposure amount control system 43. Above the wafer stage 27, an off-axis alignment sensor 36 for wafer alignment is arranged, and the main control system 41 performs wafer alignment based on the detection result.

At the time of exposure, the reticle stage 22 and the wafer stage 27 are driven to synchronously scan the reticle R and one shot area on the wafer W in the Y direction while irradiating the exposure light IL. The operation of driving the wafer 27 and step-moving the wafer W in the X and Y directions is repeated. As a result, a pattern image of the reticle R is exposed to each shot area on the ueno and W by the step-and-scan method.

Next, in the projection exposure apparatus according to the present embodiment, the characteristic relating to the pitch dependency of the line width of the projection image of the projection optical system PL, in other words, the OPE which is the optical proximity effect of the projection image An example of an operation of adjusting the characteristic of (Optical Proximity Effect) will be described. To do so, First, the OPE characteristics are obtained by simulation or actual measurement of the aerial image as follows.

[Principle of evaluating OPE characteristics when using an aberration-free projection optical system]

FIG. 2 shows a part of a pattern of a reticle TR for measuring an OPE characteristic for evaluating the OPE characteristic of the projection exposure apparatus of the present embodiment. In FIG. 'A space pattern (hereinafter referred to as “L / S pattern”) 51, a second L / S pattern 53 as an intermediate pitch pattern, and an isolated pattern 55 as a coarse and pitch pattern Is formed. Note that the X axis and the Y axis in FIG. 2 are coordinate systems when the reticle TR for measuring OPE characteristics in FIG. 2 is loaded on the reticle stage 22 in FIG.

[0044] The first L & S pattern 51 is composed of 11 halftone line patterns 52 each having a transmittance of 6% and extending in the Y direction with a width D in the X direction in the X direction at a pitch PI (> D). They are formed in an array. The second LZS pattern 53 is formed by arranging 11 line patterns 54 of 6% transmittance halftone extending in the Y direction with a width D in the X direction at a pitch P2 (> P1) in the X direction. Have been. The isolated pattern 55 is a halftone line pattern having a transmittance of 6% and extending in the Y direction with a width D in the X direction. Each of the line patterns 52 and 54 and the isolated pattern 55 is a chrome film formed on a glass substrate that transmits exposure light.

In this case, the line widths of the line patterns 52 and 54 and the isolated pattern 55 are D in common. Further, as described below, the pitch P1 of the first L & S pattern 51 is twice the line width D, and the pitch P2 of the second L & S pattern 53 is three times the line width D. That is, the ratio of the width of the line to the space of the first L & S pattern 51 is 1: 1 and the ratio of the width of the line to the space of the second L & S pattern 53 is 1: 2.

[0046] Pl = 2-D

P2 = 3 -D--(2)

Actually, between the second L & S pattern 53 and the isolated pattern 55, a plurality of L & S patterns in which line patterns having the same line width as the line pattern 54 (52) are arranged in the X direction at gradually increasing pitches. (Not shown) are also formed. In addition, the isolated pattern 55 is formed of an L & S pattern arranged in the X direction at a pitch (about 1.5-2 μm in terms of the length on a wafer) at which a line pattern can be regarded as practically infinite. Can be considered part of Wear. As described above, a plurality of (eg, 10) LZS patterns having the same line width and different pitches are formed on the OPE characteristic measurement reticle TR. These LZS patterns can be regarded as a plurality of different patterns or three or more different patterns.

[0047] The reticle TR for measuring the OPE characteristics of this example has the same line width but different pitches of the LZS pattern formed. Even if the L / S patterns with different line widths and different pitches are used, the OPE characteristics are different. It is possible to evaluate

Next, the reticle TR for measuring the OPE characteristics shown in FIG. 2 is loaded on the reticle stage 22 shown in FIG. 1 instead of the reticle R, and the images of the LZS patterns having the same line width and different pitches shown in FIG. The pitch dependency (OPE characteristic) of the line width of the projected image when projecting onto the wafer W via the is obtained. To determine the line width of the projected image, (1) project the image of each pattern of the OPE characteristic measurement reticle TR onto an unexposed wafer W and measure the line width of the resist pattern obtained by development Test print method, (2) Aerial image measurement method in which the image is scanned in the X direction at the aperture 30A of the aerial image measurement system 29 in Fig. 1 and the line width of each pattern image is measured, and (3) Computer space There is a method to obtain it by image simulation. Here, it is assumed that the OPE characteristics are obtained by a simulation of an aerial image. For this purpose, a computer 41a (computing device) for optical simulation is connected to the main control system 41 in FIG.

The exposure conditions for this simulation were as follows: the exposure wavelength was 193 nm, the numerical aperture (NA) of the projection optical system PL was 0.60, the coherence factor (σ value) of the illumination optical system 3 was 0.75, and the annular zone. For illumination, the illumination zone ratio, which is the value of the ratio of the inner diameter to the outer diameter of the annular aperture of the aperture stop 13C in FIG. 1, was set to 0.67. The coherence factor (σ value) of the illumination optical system 3 is a value obtained by dividing the reticle-side numerical aperture of the illumination optical system 3 by the reticle-side numerical aperture of the projection optical system PL. In addition, the line width D of each of the line patterns 52 and 54 and the isolated pattern 55 in FIG. 2 was set to 140 nm as a value converted into a wafer. Further, for simplicity, the projection optical system PL was assumed to be non-income, and the line width of the projected image (aerial image) of the center line pattern of the L & S pattern for each pitch on the wafer surface was calculated.

FIG. 3 shows an aerial image TRW of the reticle TR for measuring OPE characteristics shown in FIG. 2, and FIG. Then, the light amount distributions of the projected images 51W, 53W, 55W of the L & S patterns 51, 53 and the isolated pattern 55 in FIG. 2 are calculated, and the line width dl of the images 52W, 54W, 55W corresponding to the central line pattern among them is calculated. , d2, d3 were calculated. In FIG. 3, for convenience of explanation, the projection optical system PL forms an erect image. In practice, for example, the line width of the image of the center line pattern was calculated for each of the projected images of LZS patterns with ten different pitches.

FIG. 4 shows the result of the aerial image simulation. In FIG. 4, the polygonal line C7 includes the calculation result 61 of the smallest pitch to the calculation result 62 of the largest pitch (substantially isolated pattern). For each of the multiple pitches, the actual calculated line width is connected. In FIG. 4, the horizontal axis is the value (nm) obtained by converting the pitch p of the projected L & S pattern into the length on the wafer, and the vertical axis is the image of the center line pattern of the L & S pattern at that pitch p. Is the line width d (nm). This is common to the following Figs. 5 to 7 and Figs. 9 to 11.

From the pitch dependence of line width (OPE characteristic) in FIG. 4, even if the projection optical system PL has no aberration, if the pitch p of the L / S pattern changes, the line with the same line width on the reticle It can be seen that even with a pattern, an image with a different line width is formed on the image plane. Further, in practice, a slight aberration remains in the projection optical system PL in FIG. 1, so that the wavefront aberration of the projection optical system PL is obtained in advance by actual measurement, and the above-described data is obtained using the data of the wavefront aberration. By performing a simulation, it is possible to obtain the OPE characteristics unique to the projection exposure apparatus shown in FIG.

[Simulation of Change in OPE Characteristics]

Next, the exposure conditions that can be set in the projection exposure apparatus of this example include the numerical aperture of the projection optical system PL (hereinafter, referred to as “projection NA”), the illumination conditions by the illumination optical system 3 (normally, two poles, 4 poles, annular zone, small _σ, etc.), coherence factor of illumination optical system 3 (hereinafter referred to as “illumination sigma”), illumination zone ratio of annular illumination under illumination condition of illumination optical system 3, and exposure wavelength The half width of the wavelength of the exposure light IL, the amount of exposure of the exposure light IL, the amount of defocus, and the amount of tilt of the wafer surface when performing scanning exposure by tilting the upper surface (wafer surface) of the wafer with respect to the image plane. There are a type of photoresist as a photosensitive material on the wafer W, a thickness of the photosensitive material, and the like. In this example, by changing these exposure conditions, the pitch dependence of the line width (ΟΡΕ Characteristics) within a predetermined range.

First, in this example, the illumination condition is annular illumination. First, the change in the OPE characteristic in FIG. 4 when the projection NA is changed will be described.

FIG. 5 is a diagram showing changes in OPE characteristics when the projection NA is changed. The broken line C7 in FIG. 5 is the same exposure condition (exposure wavelength: 193 nm, projection NA: 0.60, illumination sigma: 0.75, illumination zone ratio: 0. 67, the simulation result of the OPE characteristic at the line pattern line width: 140 nm). The simulation in which the broken line C9 increases only the projection NA by 0.01 to 0.61 compared to the broken line C7 The result. It can be seen from FIG. 5 that when the projection NA changes, the OPE characteristics change.

Similarly, FIG. 6 is a diagram showing changes in OPE characteristics when the illumination sigma is changed.

The broken line C7 in FIG. 6 is the same exposure condition (exposure wavelength: 193 nm, projection NA: 0.60, illumination sigma: 0.75, illumination ring zone ratio: 0.67) as the line C7 in FIG. (Line width of the line pattern: 140 nm) is a simulation result of the OPE characteristic. The broken line C11 is a simulation in which only the illumination sigma is increased by 0.02 to 0.77 with respect to the case of the broken line C7. This is the result of the session. Fig. 6 shows that the OPE characteristics change when the lighting sigma changes.

[0055] Similarly, FIG. 7 is a diagram showing changes in OPE characteristics when the illumination zone ratio is changed.

The broken line C7 in FIG. 7 is the same exposure condition (exposure wavelength: 193 nm, projection NA: 0.60, illumination sigma: 0.75, illuminated ring zone ratio: 0.67) as the line C7 in FIG. (Line width of line pattern: 140 nm) is a simulation result of the OPE characteristic. In the case of the polygonal line C13, only the illumination zone ratio is increased by 0.02 to 0.69 with respect to the polygonal line C7. These are the simulation results. From FIG. 7, it can be seen that the OPE characteristics change when the illumination zone ratio changes.

[0056] Fig. 8 shows the change rate of the OPE characteristic when the projection NA, the illumination sigma, and the illumination ring zone ratio are changed. In Fig. 8, the polygonal lines C14, C15, and CI 6 indicate the projection NA, respectively. The change in the line width of the aerial image (change rate) (change rate) (nm) for the change (0.01), the change in the line width of the aerial image (change rate) (change rate) (nm) And the change amount (change rate) (nm) of the line width of the aerial image with respect to the change (0.01) of the illumination ring zone ratio. In other words, the horizontal axis in Fig. 8 is L & The pitch of the S pattern on the wafer (nm) is converted, and the vertical axis is the rate of change of the line width of the aerial image (nm). From FIG. 8, it can be seen that the rates of change of the OPE characteristics when the projection NA, the illumination sigma, and the illumination zone ratio are changed are different from each other. Similarly, the rate of change of the OPE characteristic when other exposure conditions are changed is also obtained, and the information on the rate of change of the OPE characteristic is stored in the storage unit in the main control system 41 in FIG. .

The arithmetic unit in the main control system 41 uses the information of the change rate of the OPE characteristics, as the three pattern pitch pi, p2, the line width of the OPE characteristics of _P 3 respectively become predetermined target value , The combination of the exposure conditions, and the amount of change in the exposure conditions. Note that one of the combination of the exposure conditions and the change amount of the exposure conditions may be obtained.

[Adjustment of OPE characteristics when using a projection optical system with aberration]

Next, an OPE characteristic C18 indicated by a broken line in FIG. 9 indicates an evaluation (simulation) result of the OPE characteristic when the projection optical system PL of the projection exposure apparatus in FIG. 1 has a predetermined aberration. The exposure conditions in this case (exposure wavelength: 193 nm, projection lens NA: 0.60, illumination sigma: 0.75, illumination ring ratio: 0.67, line pattern line width: 140 nm) are the same as in FIG. It is the same. On the other hand, the OPE characteristic C17 indicated by a solid broken line in FIG. 9 is an OPE characteristic obtained by simulation for another projection exposure apparatus (hereinafter, referred to as “reference projection exposure apparatus”). Since the projection optical system PL of the projection exposure apparatus of this example has a different aberration from the projection optical system of the projection exposure apparatus as a reference, the two corresponding OPE characteristics C17 and C18 are also different.

In this example, it is assumed that an OPE-corrected reticle has been created as a mask in which the variation in line width due to the pitch has been corrected in accordance with the OPE characteristic C 17 of the projection exposure apparatus serving as the reference. . Therefore, by changing the projection NA, illumination sigma, and illumination ring zone ratio of the projection exposure apparatus of this example, the OPE characteristic C18 of the projection exposure apparatus of this example is changed to the OPE characteristic C17 of the projection exposure apparatus as a reference. Consider approaching. Thereby, the OPE-corrected reticle created according to the reference projection exposure apparatus can be used in the projection exposure apparatus of the present embodiment. This means that the OPE characteristics can be adjusted for each projection exposure apparatus.

[0059] In this example, the change amount of the exposure condition such as the projection NA, the illumination sigma, and the illumination ring ratio is described. Is set within a range that does not substantially affect characteristics other than the OPE characteristics, for example, the imaging characteristics such as the resolution of the projection optical system PL. The projection NA and the amount of change in the illumination sigma in such a range that does not substantially affect the imaging characteristics of the projection optical system PL are within ± 0.05, for example, respectively. The variation of the illuminated zone ratio in a range that does not substantially affect the variation is, for example, within about ± 0.2.

First, as shown by a region C19, the line width of the aerial image at the pattern pitch of 1540 nm (= p3) between the OPE characteristic C17 and the OPE characteristic C18 in FIG. 9 is matched by adjusting the projection NA. For this purpose, the projection NA of the projection exposure apparatus shown in FIG. 1 is adjusted by a factor of 0.02 from 0.60 to 0.58 using the rate of change of the OPE characteristic of the polygonal line C14 in FIG.

The OPE characteristic C21 in FIG. 10 shows the OPE characteristic of the projection exposure apparatus of the present example after being changed from the OPE characteristic C18 in FIG. 9 by the adjustment. By adjusting, the OPE characteristic C21 at a pattern pitch of 1540 nm (= p3) of the projection exposure apparatus of this example can be made to match the OPE characteristic C17 at a pattern pitch of 1540 nm of the projection exposure apparatus as a reference. On the other hand, the OPE characteristic C21 at the pattern pitch of 490 nm (= p2) in FIG. 10 is rather open from the OPE characteristic C17, as shown in FIG.

Then, next, the illumination sigma of the projection exposure apparatus of FIG. 1 is also adjusted, and the OPE characteristic C21 at the pattern pitch of 1540 ηm and the OPE characteristic C21 at the pattern pitch of 490 nm are simultaneously set as the reference of the projection exposure apparatus. Consider matching OPE characteristic C17. For this purpose, starting from the state shown in FIG. 9 and using the rate of change of the OPE characteristics of the polygonal lines C14 and C15 in FIG. 8, the projection for matching the OPE characteristics C18 with the OPE characteristics C17 at the pattern pitches p2 and p3 is performed. Calculate the amount of change in shadow NA and lighting sigma. The information of the OPE characteristics C17 and C18 in FIG. 9 is also stored in the storage unit of the main control system 41 in FIG. 1, and the calculation unit in the main control system 41 calculates the change amount of the exposure condition. As a result, the change amount of the projection NA is 0.01, and the change amount of the illumination sigma is 0.03.

[0062] The OPE characteristic C24 in Fig. 11 is such that the projection NA is adjusted from 0.60 to 0.61 and the lighting sigma is adjusted from 0.75 to 0.78 from the state in Fig. 9. The OPE characteristics of the projection exposure apparatus are shown. The OPE characteristic C17 of FIG. 11 is the OPE characteristic of the projection exposure Sex Same as C17.

By simultaneously adjusting the projection NA and the illumination sigma of the projection exposure apparatus of the present example so as to make an effort from the areas C26 and C27 in FIG. 11, the pattern pitch of the projection exposure apparatus of the present example at 1540 nm (= p3) can be obtained. The OPE characteristic C24 and the reference OPE characteristic C17 at the pattern pitch of 1540 nm of the projection exposure apparatus were matched, and at the same time, the OPE characteristic C24 of the projection exposure apparatus of the present example at the pattern pitch of 490ηm (= p2), And the OPE characteristic C 17 at a pattern pitch of 490 nm of the projection exposure apparatus. Further, in this example, by adjusting the exposure amount, for example, the two OPE characteristics C17 and C24 at the pitch 280 nm (= pl), which is the smallest pattern pitch, also match! /.

As described above, the operation of matching the OPE characteristic C24 with the reference OPE characteristic C17 at three pattern pitches adjusts the line widths of the projection images of a plurality of different patterns to a predetermined state. In addition, it corresponds to the operation of changing the exposure condition for exposing the wafer. As a result, the adjusted OPE characteristic C24 of the projection exposure apparatus of this example and the reference OPE characteristic C17 of the projection exposure apparatus are the smallest measured pitch pi, the larger intermediate pitch p2, and the substantial In other words, three pitches, p3, which can be regarded as an isolated pattern, are consistent. Therefore, the L & S patterns with the pitches pi, p2, and ρ3 converted on these wafers can be regarded as the first, second, and third periodic patterns having different pitches from each other.

Similarly, by simultaneously adjusting one or more of the projection NA, the illumination sigma, and the illumination ring ratio, the OPE characteristic of the projection exposure apparatus can be adjusted at three different pattern pitches. Can be. If there are four or more pattern pitches to be adjusted, use a combination of projection NA, illumination sigma, and illumination zone ratio that minimizes the standard deviation of the deviation of the overall OPE characteristics using a root mean square optimization method, etc. Can be guided. Further, by changing all of the above exposure conditions as the exposure conditions, the OPE characteristics can be adjusted at more pitches. Then, the main control system 41 in FIG. 1 actually sets the exposure conditions adjusted as described above and performs exposure on the wafer W.

According to this example, the OPE characteristics can be adjusted for each projection exposure apparatus. Therefore, in the projection exposure apparatus of this example, the OPE characteristics created for the projection exposure apparatus serving as the reference are compensated. Since a corrected reticle can be used, there is no need to create a new reticle with OPE characteristics corrected, and manufacturing costs can be reduced. As a result, each time a new projection exposure apparatus is introduced, it is not necessary to create a new OPE-corrected reticle, thus greatly reducing the cost in the exposure process.

In the above embodiment, the OPE characteristic C17, which is the reference in FIG. 9, is the OPE characteristic of the projection exposure apparatus that is the reference. However, the OPE characteristic C17 may be determined according to, for example, the characteristic of a device pattern to be exposed. Further, the OPE characteristic C17 may be, for example, such as a predetermined standard.

[Second embodiment]

Next, a second embodiment of the present invention will be described with reference to FIGS. 1 to 3 and FIGS. Also in this example, the scanning exposure type projection exposure apparatus (exposure apparatus) shown in FIG. 1 is used. In this example, unevenness in the light amount distribution (hereinafter referred to as “brightness distribution”) of exposure light (exposure beam) on the pupil plane of the illumination optical system 3 in FIG. In order to adjust the OPE characteristic, which is a characteristic relating to the pitch dependency of the line width of the projected image caused by the exposure light within the exposure light, predetermined exposure conditions similar to those in the first embodiment are used. To adjust. For this purpose, as in the first embodiment, the OPE characteristics are obtained by simulation or actual measurement of the aerial image as follows.

A plurality of patterns for measuring the OPE characteristics used in this example include a first LZS pattern 51 as a fine pitch pattern in FIG. 2 and a pattern as an intermediate pitch pattern as in the first embodiment. It is arranged between the second L / S pattern 53, the isolated pattern 55 as a coarse and pitch pattern, and the second L & S pattern 53 and the isolated pattern 55, and has the same line as the line pattern 54 (52). It includes a plurality of L & S patterns (not shown) in which line patterns of a width are arranged in the X direction at increasingly larger pitches. These L / S patterns can be considered as multiple different patterns or three or more different patterns.

Next, instead of reticle R, reticle TR for measuring OPE characteristics shown in FIG. 2 is loaded onto reticle stage 22 shown in FIG. 1, and images of LZS patterns having the same line width and different pitches shown in FIG. 2 are projected. When projecting onto wafer W via optical system PL, pitch dependence of line width of projected image (OPE characteristics). Here, it is assumed that the OPE characteristics are obtained by a simulation of an aerial image. For this purpose, a computer 41a (arithmetic unit) for optical simulation is connected to the main control system 41 (control unit) in FIG.

The exposure conditions for this simulation were as follows: the exposure wavelength was 193 nm, the projection NA (numerical aperture of the projection optical system PL) was 0.60, the illumination sigma (coherence factor of the illumination optical system 3) was 0.75, In order to perform annular illumination, the illumination annular ratio (inner diameter Z outer diameter) of the annular aperture of the aperture stop 13C in FIG. 1 was set to 0.67. Further, the line width D of each of the line patterns 52 and 54 and the isolated pattern 55 in FIG. 2 was set to 140 nm as a value converted on the wafer, and each line pattern was a halftone having a transmittance of 6%. Further, for simplicity, the projection optical system PL has no aberration, and it is assumed that there is no luminance unevenness of the exposure light in the pupil plane of the illumination optical system 3, and the L & S pattern of each pitch on the wafer surface is The line width of the projected image (aerial image) of the central line pattern was calculated.

FIG. 12 shows the result of the aerial image simulation. In FIG. 12, the broken line E7 includes the calculation result 62E of the largest pitch (substantially isolated pattern) from the calculation result 61E of the smallest pitch. It connects the actually calculated line widths for multiple pitches. In FIG. 12, the horizontal axis represents the value (nm) obtained by converting the pitch p of the projected L & S pattern into the length on the wafer, and the vertical axis represents the image of the center line pattern of the L & S pattern at that pitch p. Is the line width d (nm). This is common to FIGS. 14 to 17, FIG. 19 to FIG. 22, and FIG. 24 below.

Note that the simulation in FIG. 12 is a calculation result when the exposure amount is set so that the line width of the image of the isolated pattern (calculation result 62E) is 140 nm, and thus the characteristic of the polygonal line E7 in FIG. Is different from the characteristic of the polygonal line C7 in FIG.

From the pitch dependency of line width (OPE characteristic) in Fig. 12, even if the projection optical system PL has no aberration, if the pitch p of the LZS pattern changes, even if the line pattern has the same line width on the reticle, It can be seen that images having different line widths are formed on the image plane. Actually, since a slight aberration remains in the projection optical system PL in FIG. 1, the wavefront aberration of the projection optical system PL is determined in advance by actual measurement, and the above-described data is obtained using the data of the wavefront aberration. By performing the simulation, the OPE characteristic unique to the projection exposure apparatus in FIG. 1 can be obtained as in the first embodiment. Further, actually, the luminance distribution of the exposure light in the pupil plane of the illumination optical system 3 has a certain degree of luminance unevenness, which is not an ideal flat distribution. Since the luminance unevenness differs for each projection exposure apparatus, in order to adjust the OPE characteristic with high accuracy for each projection exposure apparatus, it is necessary to consider a change in the OPE characteristic caused by the luminance unevenness.

FIG. 13 shows an example of luminance unevenness during annular illumination in the pupil plane. In FIG. 13, the horizontal axis represents the position of the pupil plane in the radial direction converted to illumination sigma, and the vertical axis represents the position. Is a value obtained by standardizing the luminance (light quantity) at the position in the radial direction so that the maximum value is 1. In FIG. 13, a flat (top-hat-shaped) distribution E8 is an ideal luminance distribution, and the simulation result in FIG. 12 is calculated under the distribution E8. In contrast to distribution E8, distribution E9 is a luminance distribution with a central convexity where the luminance increases in the center, and distribution E10 is a luminance distribution with a tendency to decrease in which the luminance gradually increases in the orbital zone toward the outer periphery. Are shown respectively.

As shown in FIG. 12, the line width (OPE) of the aerial image with respect to the pattern pitch is used as in FIG. The characteristics) obtained by simulation are shown by the polygonal lines E11 and E12 in Fig. 14, respectively. Also in this simulation, the exposure is set so that the line width of the isolated line is 140 nm. This is the same in the following simulation. In FIG. 14, the broken line E7 of FIG. 12 is also displayed.

In FIG. 14, in the case of the ideal luminance distribution (polyline E7), the OPE characteristic of the luminance distribution having a tendency to be convex (polyline El 1) is slightly shifted especially in the region of the medium pitch. It can be seen that in the luminance distribution (polyline E12) that tends to decrease in the inside, the OPE characteristic shifts in the small pitch, large, and pitch regions. Since such a luminance distribution differs depending on the projection exposure apparatus, an actual projection exposure apparatus has a unique OPE characteristic due to the luminance distribution in the pupil plane of the illumination optical system.

Therefore, first, when the luminance distribution in the pupil plane during annular illumination of the projection exposure apparatus of FIG. 1 is a distribution E9 having a tendency to be convex in FIG. 13, predetermined exposure conditions are adjusted. The following describes how to make the OPE characteristics closer to the OPE characteristics in an ideal luminance distribution. The exposure conditions that can be set for the projection exposure apparatus of this example include the projection NA, the illumination conditions by the illumination optical system 3 (usually, an annular zone, deformation (2 poles, 4 poles, etc.), small σ, etc.), illumination sigma, Illumination of zonal illumination The ratio of the annular zone, the exposure wavelength, the half width of the wavelength of the exposure light IL, the exposure amount of the exposure light IL, the type of the photoresist as the photosensitive material on the wafer W, the thickness of the photosensitive material, etc. is there. In this example, the ΟΡΕ characteristics are adjusted within a predetermined range by changing these exposure conditions. Also in this example, the amount of change in the exposure conditions such as the projection ΝΑ, the illumination sigma, and the illumination ring ratio is substantially different from the characteristics other than the ΟΡΕ characteristics, for example, the imaging characteristics such as the resolution of the projection optical system PL. Set within the range that does not affect.

First, the change in the OPE characteristic (polyline El 1) in FIG. 14 when the projection NA is changed under the annular illumination of the distribution E 9 in which the luminance distribution has a mid-convex tendency in FIG. Will be explained.

FIG. 15 is a diagram showing changes in OPE characteristics when the projection NA is changed. The solid line E11 in FIG. 15 is the same exposure condition (exposure wavelength: 193 nm, projection NA: 0.60, illumination sigma: 0.75, illumination ring zone ratio: 0. 67, the line pattern line width: 140 nm) is a simulation result of the OPE characteristic. The dotted broken line E14 is obtained by increasing only the projection NA by 0.01 and setting it to 0.61 compared to the broken line E11. It is a simulation result of. As can be seen from Fig. 15, the OPE characteristic changes when the projection NA changes.

Similarly, FIG. 16 is a diagram showing a change in the OPE characteristic when the illumination sigma is changed under the annular illumination having a luminance distribution E9 in FIG. The solid line E11 in FIG. 16 is the same exposure condition (exposure wavelength: 193 nm, projection NA: 0.60, illumination sigma: 0.75, illuminated zone ratio) as the solid line E11 in FIG. : 0.67, line pattern line width: 140 nm) is a simulation result of the OPE characteristics. The dotted broken line E15 is obtained by increasing only the illumination sigma by 0.01 in the case of the broken line E11. This is the simulation result when 76 is set. From FIG. 16, it can be seen that when the illumination sigma changes, the OPE characteristics change.

Similarly, FIG. 17 is a diagram showing changes in OPE characteristics when the illumination ring zone ratio is changed under the zone illumination of the distribution E9 in which the luminance distribution has a mid-convex tendency in FIG. is there. The solid line E11 in FIG. 17 is the same exposure condition (exposure wavelength: 193 nm, projection) as the line E11 in FIG. (NA: 0.60, illumination sigma: 0.75, illumination zone ratio: 0.67, line pattern line width: 140 nm) This is a simulation result of OPE characteristics. This is a simulation result when only the illumination zone ratio is increased by 0.01 to 0.68. From FIG. 17, it can be seen that the OPE characteristics change when the illumination zone ratio changes.

[0079] Fig. 18 shows the rate of change of the OPE characteristics when the projection NA, the illumination sigma, and the illumination zone ratio are changed under the annular illumination of the distribution E9 in which the luminance distribution is the mid-convex distribution in Fig. 13. In Fig. 18, the polygonal lines E17, E18, and El 9 indicate the change in the line width of the aerial image (change rate) (nm) and the change in the illumination sigma (nm) with respect to the change in the projection NA (0.01), respectively. The change in the line width of the aerial image (rate of change) (nm) against (0.01) and the change in the line width of the aerial image (rate of change) (nm) with respect to the change in the illuminated zone ratio (0.01) is there. That is, the horizontal axis in FIG. 18 is the pitch (nm) converted on the wafer of the L & S pattern, and the vertical axis is the change rate (nm) of the line width of the aerial image. From Fig. 18, it can be seen that the rates of change of the OPE characteristics when the projection NA, illumination sigma, and illumination ring zone ratio are changed are different from each other. Similarly, the rate of change of the OPE characteristic when other exposure conditions are changed is also obtained, and the information on the rate of change of the OPE characteristic is stored in the storage unit in the main control system 41 in FIG. .

Next, the arithmetic unit in the main control system 41 uses the information on the rate of change of the OPE characteristic and, for example, by means of a root mean square optimization method or the like, the luminance distribution is shown in FIG. The OPE characteristic under the annular illumination is projected so that the standard deviation of the deviation over the entire pattern pitch is minimized with respect to the OPE characteristic of the ideal luminance distribution (polyline E7 in Fig. 14). Determine (optimize) the combination of NA, lighting shima, and lighting zone ratio and the amount of change. As a result, as an example, the change amount of the projection NA is 0, the change amount of the illumination sigma is 0.03, and the change amount of the illumination ring ratio is 0.01. These exposure conditions are set in the projection exposure apparatus of FIG. The combination of the projection NA, the illumination sigma, and the illumination ring zone ratio, and the amount of change thereof can be arbitrarily set according to the target standard deviation.

FIG. 19 shows the OPE characteristics after optimizing the exposure conditions in such a manner. In FIG. 19, the polygonal lines E 7 and El 1 indicate the ideal luminance distribution and the luminance of the central convexity shown in FIG. 14, respectively. And illumination conditions (exposure wavelength: 193 nm, projection NA: 0.60, It shows the OPE characteristics when the lighting sigma is 0.75 and the lighting zone ratio is 0.67). In addition, the polygonal line E20 performs ring illumination with a luminance distribution with a tendency to be convex, and the OPE after optimizing the projection NA to 0.60, the illumination sigma to 0.78, and the illumination ring ratio to 0.66. The characteristics are shown. Compared to the OPE characteristic before optimization of the exposure condition (polyline E11), the OPE characteristic after the optimization of the exposure condition (polyline E20) is the OPE characteristic when the luminance distribution in the pupil plane is ideal. The degree of coincidence with the characteristic (polyline E7) is high, indicating that the OPE characteristic is effectively corrected.

Next, when the luminance distribution in the pupil plane during annular illumination of the projection exposure apparatus in FIG. 1 is a distribution E10 having a decreasing tendency in FIG. 13, a predetermined exposure condition is adjusted. The following describes how to make the OPE characteristics closer to the OPE characteristics in an ideal luminance distribution. First, the change of the OPE characteristic (polyline E12) of FIG. 14 when the projection NA is changed under the annular illumination of the distribution E10 in which the luminance distribution decreases in FIG. 13 will be described.

FIG. 20 is a diagram showing changes in OPE characteristics when the projection NA is changed. The broken line E12 in FIG. 20 is the same exposure condition (exposure wavelength: 193 ηm, projection NA: 0.60, illumination sigma: 0.75, illumination ring zone ratio: 0.67) as the line E12 in FIG. (Line width of the line pattern: 140 nm) is the simulation result of the OPE characteristic.The polygonal line E22 is the simulation result when only the projection NA is increased by 0.011 to 0.61 with respect to the polygonal line E12. Yeong result. From Fig. 20, it is clear that when the projection NA changes, the OPE characteristics change.

Similarly, FIG. 21 is a diagram showing a change in the OPE characteristic when the illumination sigma is changed under the annular illumination of the distribution E10 in which the luminance distribution decreases in FIG. The polygonal line E12 in FIG. 21 shows the same exposure conditions (exposure wavelength: 193 nm, projection NA: 0.60, illumination sigma: 0.75, illumination ring zone ratio: 0.67, (Line width of line pattern: 140 nm) is a simulation result of the OPE characteristics. The broken line E23 is the simulation result when only the lighting sigma is increased by 0.01 to 0.76 compared to the broken line E12. It is. From FIG. 21, it can be seen that when the illumination sigma changes, the OPE characteristics change.

Similarly, FIG. 22 is a diagram showing a change in the OPE characteristic when the illumination ring zone ratio is changed under the ring illumination of the distribution E10 in which the luminance distribution decreases in FIG. . Line in Figure 22 E12 is the same exposure condition (exposure wavelength: 193 nm, projection NA: 0.60, illumination sigma: 0.75, illumination zonal ratio: 0.67, line width of the line pattern obtained the polygonal line E12 in FIG. 14 : 140 nm) is the simulation result of the OPE characteristic, and the polygonal line E24 is the simulation result when only the illumination zone ratio is increased by 0.01 to 0.68 with respect to the polygonal line E12. From FIG. 22, it can be seen that the OPE characteristics change when the illumination zone ratio changes.

[0086] Fig. 23 shows the rate of change of the OPE characteristics when the projection NA, the illumination sigma, and the illumination zone ratio are changed under the annular illumination of E10 in which the luminance distribution decreases in Fig. 13. In FIG. 23, the polygonal lines E25, E26, and E27 indicate the change in the line width of the aerial image (change rate) (nm) and the change in the illumination sigma (nm) with respect to the change in the projection NA (0.01), respectively. 01) is the change in the line width of the aerial image (rate of change) (nm) relative to the change in the illumination zone ratio (0.01), and the change in the line width of the aerial image (change rate) (nm) is the change in the annular zone ratio (0.01) . That is, the horizontal axis in FIG. 23 is the pitch (nm) converted on the wafer of the L & S pattern, and the vertical axis is the rate of change of the line width of the aerial image (nm). From FIG. 23, it can be seen that the rates of change of the OPE characteristics when the projection NA, the illumination sigma, and the illumination zone ratio are changed are different from each other. Similarly, the rate of change of the OPE characteristic when other exposure conditions are changed is also obtained, and the information on the rate of change of the OPE characteristic is stored in the storage unit in the main control system 41 in FIG. .

Next, the arithmetic unit in the main control system 41 uses the information on the rate of change of the OPE characteristic and, for example, by a root mean square optimization method or the like, the luminance distribution in FIG. The projection NA, the projection NA, and the OPE characteristic under the illumination of the annular zone are set so that the standard deviation of the deviation over the entire pattern pitch is minimized with respect to the OPE characteristic of the ideal luminance distribution (polyline E7 in Fig. 14). Determine (optimize) the combination of lighting sigma and lighting zone ratio and the amount of change. As a result, as an example, the change amount of the projection NA is 0, the change amount of the illumination sigma is 0, and the change amount of the illumination ring zone ratio is 0.2. These exposure conditions are set in the projection exposure apparatus of FIG. The combination of the projection NA, the illumination sigma, and the illumination zone ratio and the amount of change can be set arbitrarily according to the target standard deviation.

FIG. 24 shows the OPE characteristics after optimizing the exposure conditions in such a manner. In FIG. 24, the broken lines E7 and E12 indicate the ideal luminance distribution and the luminance distribution of the inward decreasing tendency shown in FIG. 14, respectively. And the exposure conditions (exposure wavelength: 193 nm, projection NA: 0.6 0, lighting sigma: 0.75, lighting zone ratio: 0.67). In addition, the polygonal line E28 (which almost matches the polygonal line E7) performs zonal illumination with a luminance distribution that tends to decrease in the inside, and also has a projection NA of 0.60, an illumination sigma of 0.75, and an illumination zonal ratio. The OPE characteristics after optimization to 0.47 are shown. Compared to the OPE characteristic before optimization of the exposure condition (polyline E12), the OPE characteristic after optimization of the exposure condition (polyline E28) is the OPE characteristic when the luminance distribution in the pupil plane is ideal. The degree of coincidence with the characteristic (polyline E7) becomes higher, which indicates that the OPE characteristic is effectively corrected.

As described above, according to this example, when the brightness of the exposure light is uneven in the pupil plane of the illumination optical system, the OPE characteristic is adjusted by adjusting the exposure condition of the projection exposure apparatus. It can be almost matched with the OPE characteristics when the light brightness distribution is ideal. Therefore, in the projection exposure apparatus of this example, for example, a reticle with OPE characteristics corrected for another projection exposure apparatus can be used. Can be reduced. As a result, it is not necessary to create a new OPE-corrected reticle each time a new projection exposure apparatus is introduced, so that the cost in the exposure process can be significantly reduced.

As described above, in the present example, the OPE characteristics of the luminance distribution E9 having the convexity in the middle and the luminance distribution E10 of the decreasing tendency in FIG. We considered matching the characteristics. For example, the OPE characteristic (line E11 in FIG. 14) of the luminance distribution E9 having a convexity in the middle is matched with the OPE characteristic (line E12 in FIG. 14) of the luminance distribution E10 having an inward decreasing tendency. Is similarly possible. Conversely, it is also possible to match the OPE characteristic (polyline E12) in the luminance distribution E10 with a tendency to decrease inside with the OPE characteristic (polyline E11) in the luminance distribution E9 with a mid-convex tendency.

The illumination condition is not limited to the annular illumination, and the OPE characteristic is adjusted to a predetermined state by adjusting the exposure condition according to the brightness unevenness in the pupil plane under any illumination condition. OPE characteristics can be matched between projection exposure apparatuses having differences in luminance unevenness in the pupil plane.

[Third embodiment]

Next, a third embodiment of the present invention will be described with reference to FIGS. This example Is an application of the present invention to an exposure system in which a plurality of projection exposure apparatuses (exposure apparatuses) are operated in parallel. In FIG. 25, parts corresponding to FIG. Description is omitted.

FIG. 25 shows a schematic configuration of the exposure system of the present example. In FIG. 25, the exposure system of the present example controls a first exposure apparatus 1A, a second exposure apparatus 1B, and these. The first and second exposure apparatuses 1A and 1B are both configured to include a host computer 4, and are both step-and-scan type projection exposure apparatuses, that is, scanning exposure type exposure apparatuses. Although not shown, the exposure system includes a coater / developer for applying and developing a resist on a wafer. In this example, for example, in order to expose a wafer for a device to be mass-produced, the same reticle pattern is exposed to each wafer by two exposure apparatuses 1A and 1B. .

First, in the first exposure apparatus 1A of FIG. 25, the exposure light from the illumination optical system 3A illuminates the reticle Ml. The pattern in the illumination area of the reticle Ml illuminated by the exposure light is converted into a slit-like exposure light in the shot area SAA on the wafer W1 on which the photoresist is applied at a predetermined projection magnification | 8 through the projection optical system PLA. The image is reduced and projected on the area. Hereinafter, the Z axis is taken parallel to the optical axis of the projection optical system PLA, and the scanning direction of the reticle Ml and the wafer W1 is defined as the Y axis on a plane perpendicular to the Z axis, and the non-scanning direction is defined as the X axis. This is the same for the second exposure apparatus 1B.

[0094] The reticle Ml is held on the reticle stage 22A, and the reticle stage 22A can be continuously moved in the Y direction by, for example, a linear motor system on the reticle base 23A, and can be finely moved in the X, Y, and rotation directions. It is placed on. On the other hand, the wafer W1 is held on a wafer stage 27A via a wafer holder (not shown). The wafer stage 27A can be continuously moved in the Y direction on the wafer base 28A by, for example, a linear motor system, and can be moved in the X and Y directions. It is configured to be able to move stepwise in the Y direction.

[0095] As shown in Fig. 25, the position of the reticle stage 22A (reticle Ml) in the Y and X directions and the rotation angle are determined by an interferometer system including the moving mirrors 44YA1 and 44YA2 and the laser interferometers 45YA1 and 45YA2. And moving mirror 44XA, laser interferometer 45XA, and interferometer system Measured by the system. Similarly, the position of the wafer stage 27A (wafer W1) in the X and Y directions is determined by the interferometer system including the moving mirror 46XA and the laser interferometer 47XA, and the moving mirror 46YA and the laser interferometer 47YA and the laser interferometer. Are measured with high precision by the interferometer system. Based on these measurement results, a stage drive system (not shown) controls the reticle stage 22A and the wafer stage 27A under the control of a main control system 41A (control device) that controls the overall operation of the exposure apparatus 1A. Control behavior.

[0096] Further, in order to superimpose the pattern image of the reticle Ml and the pattern already formed on the wafer W with high accuracy during the overlay exposure, an alignment sensor is provided on the side of the projection optical system PLA. 36A is installed. During exposure, the reticle Ml is irradiated with exposure light to move the reticle stage 22A (reticle Ml) and the wafer stage 27A (wafer W1) in the Y direction in synchronization with each other, and the wafer stage 27A is moved in the X direction. By repeating the operation of stepping in the Y direction, the pattern of the reticle Ml is transferred to each shot area SAA on the wafer W1.

Next, the second exposure apparatus 1B shown in FIG. 25 includes an illumination optical system 3B, a reticle stage 22B holding a reticle M2, a reticle base 23B, and a laser interferometer 45YB1 similarly to the first exposure apparatus 1A. , 45YB2, 45XB, projection optical system PLB, wafer stage 27B holding wafer W2, wafer base 28B, laser interferometers 47XB, 47YB, alignment sensor 36B, and main control system 41B. Moving mirrors 44YB1, 44YB2, 44XB are fixed to reticle stage 22B, and moving mirrors 46XB, 46YB are fixed to wafer stage 27B. Also in this exposure apparatus 1B, at the time of exposure, reticle M2 is irradiated with exposure light to move reticle stage 22B (reticle M2) and wafer stage 27B (wafer W2) in the Y direction in synchronism with each other. By repeating the operation of moving the stage 27B stepwise in the X and Y directions, the pattern of the reticle M2 is transferred to each shot area SAB on the wafer W2.

Next, an example of an operation for matching the OPE characteristics of the two exposure apparatuses 1A and 1B in the exposure system of the present example will be described with reference to FIG.

First, in step 101 in FIG. 26, the OPE characteristics (for example, the OPE characteristics C17 in FIG. 9) of the first exposure apparatus 1A as the reference projection exposure apparatus are simulated. Ask. In the next step 102, the OPE characteristic (for example, the OPE characteristic C18 in FIG. 9) of the second exposure apparatus 1B, which is the projection exposure apparatus to be adjusted, is determined by simulation of the aerial image. Since the exposure apparatuses 1A and 1B of the present example are controlled by the host computer 4, the simulation of the aerial image is performed by the host computer 4.

[0099] Next, in step 103, the host computer 4 determines the difference between the line widths of the OPE characteristics of the two exposure apparatuses 1A and IB at the three pattern pitches pi, p2 and p3 in Fig. 10, for example. And verify that it is below the specified tolerance. If any of these deviations exceeds the permissible value, the operation proceeds to step 104, where the host computer 4 sends the line width deviation information and the OPE characteristic information of the exposure apparatus 1B to the main control of the exposure apparatus 1B. Supply to system 41B. In response to this, using, for example, the same information as the change rate of the OPE characteristic in FIG. 8, the main control system 41B converts the OPE characteristic of the exposure apparatus 1B into the three pitches pi, p2, and the OPE characteristic of the exposure apparatus 1A. The combination of exposure conditions for matching at p3 and the amount of change in the exposure conditions are determined. In the next step 105, the main control system 41B sets the adjusted exposure conditions (illumination conditions, exposure amount, etc.) in the illumination optical system 3B and the projection optical system PLB, etc., and hosts the information on the set exposure conditions. Supply to computer 4.

Next, the operation returns to step 102 again, and the host computer 4 obtains the OPE characteristics of the second exposure apparatus 1B again. However, in order to more accurately obtain the OPE characteristics, the OPE characteristics measurement reticle TR shown in Fig. 2 may be actually loaded instead of the reticle M2, and the OPE characteristics may be obtained by a test print or aerial image measurement. .

In the next step 103, the host computer 4 again determines that the difference between the line widths of the OPE characteristics of the two exposure apparatuses 1A and IB at the three pattern pitches pi, p2 and p3 in FIG. Check if it is. When these deviations are not more than the allowable value, the adjustment (optimization) of the OPE characteristics of the second exposure apparatus 1B is completed.

[0101] Thereafter, in Fig. 25, the reticle M2 having the OPE characteristics corrected for the first exposure apparatus 1A is used as it is in the second exposure apparatus 1B, and the line width for each pitch is not changed. Uniformity can be eliminated. Therefore, the manufacturing cost can be significantly reduced. Also in this example, the OPE characteristics of the two exposure apparatuses 1A and 1B should be matched with three or more pattern pitches. [0102] As described above, in this example, two exposure apparatuses 1A and IB perform, for example, exposure of a device pattern of the same layer. However, the two exposure apparatuses 1A and 1B may be used to perform the overlay exposure by the mitigation 'and' match method. That is, for example, after the first exposure apparatus 1A performs exposure on the first layer on the wafer, the second exposure apparatus 1B performs overlay exposure on the second layer above the wafer on the second layer. Yeah. Even in this case, since the OPE characteristics of the two exposure apparatuses 1A and 1B are adjusted in the same manner in this example, the overlay accuracy and the like are improved.

[0103] The present invention can be similarly applied to the case where exposure is performed not only by a scanning exposure type exposure apparatus but also by a batch exposure type exposure apparatus. Further, the present invention can be applied to an immersion type exposure apparatus disclosed in, for example, International Publication No. (WO) No. 99Z49504. Also, a plurality of projection exposure apparatuses (exposure apparatuses) of the above-described embodiment are provided. The illumination optical system and the projection optical system composed of the lenses described above are integrated into the exposure apparatus main body, optically adjusted, and a reticle stage and a wafer stage composed of many mechanical parts are attached to the exposure apparatus main body, and wiring and piping are connected. Furthermore, it can be manufactured by performing comprehensive adjustment (electrical adjustment, operation confirmation, etc.). It is desirable that the exposure apparatus be manufactured in a clean room in which the temperature, cleanliness, etc. are controlled.

In the case where a semiconductor device is manufactured using the projection exposure apparatus (exposure apparatus) according to the above-described embodiment, the semiconductor device has a step of performing function and performance design of the device. Manufacturing a reticle, forming a silicon material wafer, aligning the reticle pattern on the wafer by performing alignment using the projection exposure apparatus of the above-described embodiment, and forming a circuit pattern such as etching. It is manufactured through chip, device assembly steps (including dicing, bonding, and package steps), and inspection steps.

[0105] The application of the exposure apparatus of the present invention is not limited to the exposure apparatus for manufacturing semiconductor devices, and for example, a liquid crystal display element formed on a square glass plate, or a display apparatus such as a plasma display. To manufacture various devices such as exposure equipment for imaging, imaging devices (CCD, etc.), micro machines, thin film magnetic heads, and DNA chips. Widely applicable to an exposure apparatus for Further, the present invention can be applied to an exposure step (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed by using a lithographic process.

[0106] The present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention. In addition, Japanese Patent Application No. 2003-405226 filed on December 3, 2003, including the description, claims, drawings, and abstracts, and Japanese Patent Application No. 2004-June 18, 2004 filed on June 18, 2004 The entire disclosure of 181827 is hereby incorporated by reference in its entirety.

Industrial applicability

According to the device manufacturing method of the present invention, for example, each time a new exposure apparatus is introduced, it is not necessary to create a mask with a new OPE characteristic correction. The cost in the process can be significantly reduced.

Claims

The scope of the claims

[1] An exposure method for illuminating a first object with an exposure beam having an illumination optical system power and exposing a second object with the exposure beam via the first object and a projection optical system,

An exposure condition for exposing the second object is changed in order to adjust each of line widths of a plurality of patterns projected from the projection optical system through the projection optical system to a predetermined state. Exposure method.

2. The exposure method according to claim 1, wherein line widths of three or more different patterns projected through the projection optical system through the projection optical system are respectively adjusted to corresponding reference values.

[3] A change in the line width of the projection image caused by unevenness in the light amount distribution of the exposure beam on a pupil plane of the illumination optical system or a conjugate plane with the pupil plane is adjusted to the predetermined state. The exposure method according to claim 1, wherein

4. The light amount distribution according to claim 3, wherein the light amount distribution is such that the light amount of the exposure beam is substantially uniformly distributed in a circular area, an annular area, or a plurality of eccentric areas. Exposure method.

[5] The exposure conditions are plural,

The exposure method according to any one of claims 1 to 4, wherein the exposure condition is adjusted within a range that does not substantially affect an imaging characteristic of the projection optical system.

[6] The plurality of patterns are three or more types,

6. The method according to claim 1, wherein three or more exposure conditions are set to match the line widths of the projected images of the three or more types of patterns with corresponding reference values. Exposure method according to item.

7. The exposure method according to claim 6, wherein the three or more types of patterns include first, second, and third periodic patterns having different pitches from each other.

[8] The method according to any one of claims 1 to 7, wherein before changing the exposure condition, a line width of a projected image of the plurality of patterns via the projection optical system is obtained. Exposure method.

[9] The exposure conditions include a numerical aperture of the projection optical system, a coherence factor of the illumination optical system, an illumination zone ratio of annular illumination under illumination conditions of the illumination optical system, and an exposure beam. The wavelength of the exposure beam, the half width of the wavelength of the exposure beam, the exposure amount of the exposure beam, and the type of photosensitive material on the second object, wherein The exposure method according to any one of claims 1 to 3.

[10] In an exposure method using a first exposure apparatus that exposes an object via a first projection optical system and a second exposure apparatus that exposes an object via a second projection optical system, ,

The second exposure is performed to adjust the line widths of three or more types of different patterns projected through the second projection optical system to the line widths of the projection images transmitted through the first projection optical system. An exposure method comprising setting exposure conditions of an apparatus.

[11] In order to adjust the line widths of the three or more types of patterns projected through the second projection optical system to the line widths of the projection images transmitted through the first projection optical system, respectively, 11. The exposure method according to claim 10, wherein three or more exposure conditions of the second exposure device are set.

[12] The exposure conditions set include the numerical aperture of the second projection optical system, the coherence factor of the illumination optical system of the second exposure apparatus, and the annular illumination under the illumination conditions of the illumination optical system. At least one of the illumination zone ratio, the wavelength of the exposure beam used in the second exposure apparatus, the half width of the wavelength of the exposure beam, the exposure amount of the exposure beam, and the type of photosensitive material on the object. 12. The exposure method according to claim 10, wherein:

[13] A device manufacturing method including a lithographic process is described.

13. A method for manufacturing a device, comprising: transferring a pattern onto a photoconductor under exposure conditions set by the exposure method according to claim 1 during the lithographic process.

[14] An exposure apparatus having an illumination optical system for illuminating a first object with an exposure beam, and a projection optical system for projecting an image of the first object on a second object.

In order to adjust each of line widths of projected images of the plurality of patterns different from each other through the projection optical system to a predetermined reference state, a control device that changes exposure conditions for exposing the second object is provided. An exposure apparatus comprising:

[15] In order to match the line widths of projected images of the three or more different patterns through the projection optical system to the corresponding reference values, the control device changes the exposure conditions. 15. The exposure apparatus according to claim 14, wherein the exposure is performed.

[16] In order to adjust the change in the line width of the projection image to the predetermined state due to unevenness in the light amount distribution of the exposure beam on the pupil plane of the illumination optical system or a conjugate plane with the pupil plane, 15. The exposure apparatus according to claim 14, wherein the control device changes the exposure condition.

17. The light amount distribution according to claim 16, wherein the light amount distribution of the exposure beam is such that the light amount of the exposure beam is substantially uniformly distributed in a circular area, an annular area, or a plurality of eccentric areas. Exposure equipment.

[18] The exposure conditions are plural,

18. The exposure apparatus according to claim 14, wherein the exposure condition is adjusted within a range that does not substantially affect an imaging characteristic of the projection optical system.

[19] The plurality of patterns are three or more patterns,

19. The control device changes three or more exposure conditions to adjust the line widths of the projected images of the three or more types of patterns to corresponding reference values, respectively. The exposure apparatus according to any one of the above.

20. The exposure apparatus according to claim 19, wherein the three or more types of patterns include first, second, and third periodic patterns having different pitches from each other.

21. The apparatus according to claim 14, further comprising an arithmetic device or an aerial image measurement system for obtaining line width information of the aerial image of the plurality of patterns via the projection optical system. Exposure apparatus according to Item.

[22] The exposure conditions include a numerical aperture of the projection optical system, a coherence factor of the illumination optical system, an illumination zone ratio of annular illumination under illumination conditions of the illumination optical system, a wavelength of the exposure beam, and 2. The image processing apparatus according to claim 1, wherein the wavelength is at least one of a half width of a wavelength of the exposure beam, an exposure amount of the exposure beam, and a type of a photosensitive material on the second object.

22. The exposure apparatus according to any one of 4 to 21.

23. The exposure apparatus according to claim 15, wherein the reference value is a line width of a projection image of the three or more types of patterns projected via a projection optical system of another exposure apparatus.

[24] A method of manufacturing a device including a lithographic process, 24. A device manufacturing method, wherein a pattern is transferred onto a photoreceptor by the exposure apparatus according to claim 14 during the lithographic process.