Patent Application
20070247640
The present invention relates to exposure apparatuses, exposure methods, device manufacturing methods, and surface shape detection units, and more particularly to an exposure apparatus and an exposure method in which on object is exposed via a projection optical system, a device manufacturing method that uses the exposure apparatus or the exposure method, and a surface shape detection unit that detects information related to a surface shape of a surface subject to exposure of the object.
Conventionally, in a lithographic process for manufacturing electronic devices such as semiconductor devices (integrated circuits) and liquid-crystal display devices, a projection exposure apparatus that transfers an image of a pattern on a mask or reticle (hereinafter generally referred to as a ‘reticle’) onto each shot area on a photosensitive substrate such as a wafer coated with resist (photosensitive agent) or on a glass plate (hereinafter referred to as a ‘substrate’ or ‘wafer’) via a projection optical system has been used. As this type of projection exposure apparatus, conventionally, the reduction projection exposure apparatus by the step-and-repeat method (the so-called stepper) has been mainly used, however, in recent years, the projection exposure apparatus by the step-and-scan method (the so-called scanning stepper) that performs exposure while synchronously scanning a reticle and a wafer is gathering attention.
When performing exposure using this type of exposure apparatus, in order to suppress generation of exposure defect due to defocus as much as possible, the so-called autofocus leveling control is performed in which a position of a substrate in an optical axis direction of a projection optical system is detected by a focal point position detection system (a focus detection system), and based on the detection results, an exposure area (an area to which an exposure light is illuminated) on the substrate is positioned within a range of depth of focus of the best image-forming plane of the projection optical system. Normally, as such a focal point position detection system, a multiple focal point position detection system based on an oblique method (hereinafter referred to as a ‘multipoint AF system’) is employed (for example, refer to Patent Documents 1 and 2, and the like).
However, in the projection exposure apparatus stated above, the larger the numerical aperture (NA) of the projection optical system is, the more the resolution improves, and therefore, recently, the diameter of a lens used in the projection optical system, in particular, the diameter of the lens constituting the projection optical system closest to an image plane side is getting larger. According to the larger diameter of the lens, a distance between the lens and the substrate (the so-called working distance) becomes smaller, which makes it difficult as a consequence to arrange the multipoint AF system.
Patent Document 1: Kokai (Japanese Unexamined Patent Application Publication) No. 06-283403, and
Patent Document 2: the U.S. Pat. No. 5,448,332.
Means for Solving the Problems
The present invention has been made in consideration of the situation described above, and according to a first aspect of the present invention, there is provided an exposure apparatus that performs exposure to an object via a projection optical system, the apparatus comprising: a stage that is movable in at least directions of three degrees of freedom that include an optical axis direction of the projection optical system and two-dimensional directions within a plane orthogonal to the optical axis while holding the object, and can adjust a position of the object in the optical axis direction; a first position detection unit that detects position information of the stage in the optical axis direction; a second position detection unit that detects position information of the stage within the plane orthogonal to the optical axis; a surface shape detection system that detects information related to a surface shape of a surface subject to exposure of the object held on the stage, prior to the exposure; and an adjustment unit that adjusts a surface position of the surface subject to exposure of the object by driving the stage based on the detection results of the surface shape detection system and the detection results of the first and second position detection units, when performing exposure to the object.
With this apparatus, prior to exposure, the surface shape detection system detects the information related to a surface shape of the surface subject to exposure on the object held on the stage, and when performing exposure to the object, the adjustment unit adjust a surface position of the object on the stage based on the information related to a surface shape of the surface subject to exposure detected by the surface shape detection system (the detection results of the surface shape detection system) and the detection results of the first and second position detection units. Accordingly, on exposure, without detecting the position of the object in the optical axis direction of the projection optical system by the focal point position detection system, an exposure area (an area to which an exposure light is illuminated) on the object during the exposure can be positioned within a range of depth of focus of the best image-forming plane of the projection optical system.
According to a second aspect of the present invention, there is provided an exposure method in which exposure is performed to an object via a projection optical system, the method comprising: a detection process in which information related a datum position of the object in an optical axis direction of the projection optical system is detected, along with information related to a surface shape of a surface subject to exposure of the object in the optical axis direction, prior to exposure; and an exposure process in which exposure is performed while adjusting a surface position of the surface subject to exposure of the object based on the detection results.
With this method, prior to exposure, the information related to a datum position of the object in the optical axis direction of the projection optical system is detected, along with the information related to a surface shape of the surface subject to exposure of the object in the optical axis direction, and on exposure, a surface position of the object on the stage is adjusted based on the information related to a surface shape of the surface subject to exposure and the information related to a datum position of the object in the optical axis direction. Accordingly, an exposure area (an area to which an exposure light is illuminated) on the object during the exposure can be positioned within a range of depth of focus of the best image-forming plane of the projection optical system without detecting the position of the object in the optical axis direction of the projection optical system by the focal point position detection system.
According to a third aspect of the present invention, there is provided a surface shape detection unit, comprising: a stage that can hold an object and is movable in a predetermined direction; an irradiation system that irradiates an illumination light to a strip-shaped area that the object held on the stage crosses by movement of the stage; a photodetection system that receives a reflected light of the illumination light from a surface subject to exposure of the object when the object crosses the strip-shaped area; a detection unit that detects information related to a surface shape of the surface subject to exposure of the object, based on a position deviation amount from a datum position of a photodetection position of the reflected light in the photodetection system.
With this unit, by photodetecting the reflected light generated by the irradiation light irradiated to the strip-shaped area that the object crosses during movement being reflected off an object surface, a surface shape of the object can be detected in a non-contact manner based a position deviation amount from a datum position of the photodetection position.
Further, according to a fourth aspect of the present invention, there is provided an exposure apparatus, comprising: a stage that can hold an object subject to exposure and is movable in a predetermined direction; a detection unit that has an irradiation system to irradiate an illumination light to a strip-shaped area that the object held on the stage crosses by movement of the stage and a photodetection system to receive a reflected light of the illumination light from a surface subject to exposure of the object when the object crosses the strip-shaped area, and detects information related to a surface shape of the surface subject to exposure of the object based on output of the photodetection system; and a controller that controls the stage so that the object crosses the strip-shaped area, and performs surface position adjustment of the surface subject to exposure of the object based on information of a surface shape of a substantially entire area of the surface subject to exposure of the object, the information being obtained by the object crossing the strip-shaped area once.
With this apparatus, the information of a surface shape of a substantially entire area of the surface subject to exposure of the object can be obtained in a short period of time.
Further, in a lithography process, by transferring a device pattern onto an object using the exposure apparatus of the present invention, microdevices of higher-integration can be manufactured with good productivity. Accordingly, it can also be said from another aspect that the present invention is a device manufacturing method that includes a lithography process using the exposure apparatus of the present invention. Likewise, in a lithography process, by transferring a device pattern onto an object using the exposure method of the present invention, microdevices of higher-integration can be manufactured with good productivity. Accordingly, it can also be said further from another aspect that the present invention is a device manufacturing method that includes a lithography process using the exposure method of the present invention.
In the accompanying drawings;
An embodiment of the present invention will be described based on
Exposure apparatus 100 is equipped with an illumination system 10 that includes a light source and illumination optical system (such as a movable reticle blind to be described later) and an illuminates a reticle R with an illumination light (an exposure light) IL as an energy beam, a reticle stage RST holding a reticle R, a projection unit PU, a wafer stage WST where a wafer W is mounted, a body (a part of which is shown in
Illumination system 10 is, for example as disclosed in Kokai (Japanese Unexamined Patent Application Publication) No. 2001-313250 and the corresponding U.S. Patent Application Publication No. US 2003/0025890 and the like, configured containing a light source, an illuminance uniformity optical system including an optical integrator, an illumination system aperture stop, abeam splitter, a relay lens, a variable ND filter, a reticle blind (a fixed reticle blind and a movable reticle blind) and the like (none of which are shown). Under the control of a main controller 20, illumination system 10 illuminates illumination light IL with almost uniform illuminance to a slit-shaped illumination area (an area set by the reticle blind) which longitudinal extends in an X-axis direction (a lateral direction of the page surface in
Reticle stage RST is supported by levitation, for example, via a clearance of around several μm above a reticle base (not shown) by an air bearing or the like (not shown) that is arranged on the bottom surface of reticle stage RST. On reticle stage RST, reticle R is fixed by, for example, vacuum suction (or electrostatic suction). Reticle stage RST has a structure finely drivable two-dimensionally within an XY plane (the X-axis direction, a Y-axis direction and a rotation direction around a Z-axis direction orthogonal to the XY plane (a θz direction)) perpendicular to an optical axis AX of projection optical system PL, which will be described later, by a reticle stage drive section RSC (not shown in
The position of reticle stage RST within a stage-moving plane is constantly detected at a resolution of, for example, approximately 0.5 to 1 nm with a reticle laser interferometer (hereinafter referred to as a ‘reticle interferometer’) 16 via a movable mirror 15. In this case, the position measurement is performed using a fixed mirror 14, which is fixed on a side surface of a barrel 40 constituting projection unit PU to be described later, as a datum. In actual, a Y movable mirror having a reflection surface orthogonal to the Y-axis direction and an X movable mirror having a reflection surface orthogonal to the X-axis direction are arranged on reticle stage RST, and a reticle Y interferometer and a reticle X interferometer are arranged corresponding to these movable mirrors, and further a fixed mirror for X-axis direction position measurement and a fixed mirror for Y-axis direction position measurement are arranged corresponding to the interferometers. However, in
A measurement value of reticle interferometer 16 is sent to main controller 20. Main controller 20 drives and controls reticle stage RST via reticle stage drive section RSC (refer to
Projection unit PU is supported on a barrel supporting platform 38 that constitutes a part of the body, via a flange FLG1 below reticle stage RST in
As projection optical system PL, for example, a dioptric system that is composed of a plurality of lenses (lens elements) having an optical axis AX in common, for example, in the Z-axis direction. Projection optical system PL is, for example, a both-side telecentric reduction system that has a predetermined projection magnification (such as ¼ or ⅕). Therefore, when reticle R is illuminated with illumination light IL from illumination system 10, illumination light IL passing through reticle R forms a reduced image of a circuit pattern (a reduced image of a part of the circuit pattern) of reticle R within an illumination area (the irradiation area of illumination light IL) on wafer W which surface is coated with a resist (a photosensitive agent), via projection optical system PL.
In exposure apparatus 100 of the embodiment, because exposure to which the immersion method is applied is performed, the numerical aperture NA increases, which makes the opening on the reticle side larger. Therefore, in a dioptric system made of up only lenses, it becomes difficult to satisfy the Petzval condition, which tends to lead to an increase in the size of the projection optical system. In order to prevent such an increase in the size of the projection optical system, a catadioptric system composed including mirrors and lenses may also be used.
Further, in exposure apparatus 100, in the vicinity of a lens constituting projection optical system PL closest to the image plane side (the wafer W side) (hereinafter referred to as a ‘tip lens’) 91, a liquid supply nozzle 51A and a liquid recovery nozzle 51B that constitute liquid supply/drainage system 132 are arranged. Liquid supply nozzle 51A and liquid recovery nozzle 51B are held by barrel supporting platform 38, and are arranged so that their tips face wafer stage WST which will be described later.
The other end of a supply pipe (not shown) connects to liquid supply nozzle 51A, which one end connects to a liquid supply unit 131A (not shown in
Liquid supply unit 131A is composed including a liquid tank, a compression pump, a temperature controller, a valve for controlling supply/stop of the liquid to the supply pipe, and the like. As the valve, for example, a flow rate control valve is preferably used so that not only the supply/stop of the liquid but also the flow rate can be adjusted. The temperature controller adjusts the temperature of the liquid within the liquid tank so that the temperature of the liquid is about the same level as the temperature within the chamber (not shown) where the exposure apparatus main body is housed.
Incidentally, the tank for supplying the liquid, the compression pump, the temperature controller, the valves, and the like do not all have to be equipped in exposure apparatus 100, and at least a part of them may be substituted by the equipment available in the factory where exposure apparatus 100 is installed.
Liquid recovery unit 131B is composed including a liquid tank, a suction pump, a valve for controlling recovery/stop via the recovery pipe, and the like. As the valve, a flow rate control valve is preferably used corresponding to the valve on a liquid supply unit 131A side.
Incidentally, the tank for recovering the liquid, the suction pump, the valves, and the like do not all have to be equipped in exposure apparatus 100, and at least a part of them may be substituted by the equipment available in the factory where exposure apparatus 100 is installed.
As the liquid, in this case, ultra pure water (hereinafter, it will simply be referred to as ‘water’ besides the case when specifying is necessary) that transmits the ArF excimer laser beam (light with a wavelength of 193 nm) is to be used. Ultra pure water can be obtained in large quantities at a semiconductor manufacturing plant or the like without difficulty, and it also has an advantage of having no adverse effect on the photoresist on the wafer, to the optical lenses or the like. Further, ultra pure water has no adverse effect on the environment as well as an extremely low concentration of impurities, therefore, cleaning action on the surface of wafer W and the surface of tip lens 91 can be anticipated.
Refractive index n of the water with respect to the ArF excimer laser beam is said to be around 1.44. In the water the wavelength of illumination light IL is 193 nm×1/n, shorted to around 134 nm.
Liquid supply unit 131A and liquid recovery unit 131B both have a controller, and the controllers operate under the control of main controller 20 (refer to
As is obvious from the above description, liquid supply/drainage system 132 in the embodiment is a liquid supply/drainage system for local immersion that is configured including liquid supply unit 131A, liquid recovery unit 131B, the supply pipe, the recovery pipe, liquid supply nozzle 51A and liquid recovery nozzle 51B, and the like.
Incidentally, in the above description, the case has been described where one liquid supply nozzle and one liquid recovery nozzle are arranged, in order to simplify the description. However, the present invention is not limited to this, and the configuration having multiple nozzles as disclosed in, for example, the pamphlet of the International Publication No. 99/49504, may be employed. The point is that any configuration may be used as far as the liquid can be supplied in the space between an optical member in the lowest end (a tip lens) 91 constituting projection optical system PL and wafer W.
As is shown in
Below projection optical system PL in
As is shown in
Further, a rectangular-shaped opening is formed in a part of auxiliary plate 72, and a fiducial mark plate FM is fitted into the opening. A surface of fiducial mark plate FM is made to be coplanar with auxiliary plate 72. On the surface of fiducial mark plate FM, at least one pair of first fiducial marks WM1 and WM2 for reticle alignment (not shown in
Referring back to
In actual, as shown in
Further, as is shown in
In the embodiment, a length of fixed mirror 29Z in the X-axis direction is set so that wafer interferometer 18 can constantly monitor the Z position of wafer stage WST even while wafer stage WST is moving between a position directly below projection optical system PL, a position directly below alignment system ALG to be described later, and a position at which wafer W is loaded. With this structure, the absolute Z-position of wafer stage WST can be constantly detected by the same wafer interferometer 18 regardless of the XY position of wafer stage WST.
Position information (or velocity information) of wafer stage WST including the Z position described above is sent to main controller 20. Main controller 20 controls the positions in directions of six degrees of freedom including the position within the YX plane and the Z position of wafer stage WST via wafer stage drive section WSC (not shown in
Further, exposure apparatus 100 is equipped with an aerial image measurement unit that measures an aerial image via projection optical system PL. As is shown in
As is shown in
Measurement of a projected image (an aerial image) of a measurement mark formed on reticle R by aerial image measurement unit 59 via projection optical system PL is performed based on the so-called slit-scan method. In the aerial image measurement based on the slit-scan method, slit 22 of slit plate 90 is scanned with respect to a projected image (an aerial image) of a measurement mark via projection optical system PL, illumination IL passing though the slit during the scanning is guided outside wafer stage WST by light transmitting lens 87 arranged on an extending section 57 via an optical system inside wafer stage WST. Then, the light guided outside wafer stage WST enters photodetection lens 89 that is attached to a case 92 fixed to barrel supporting platform 38 (refer to
Incidentally, when performing the aerial image measurement described above, as in the space between tip lens 91 and wafer W, a constant amount of water Lq (refer to
In
In a state where the aerial image is formed, when wafer stage WST is driven in the Y-axis direction by main controller 20 via wafer stage drive section WSC (refer to
Referring back to
Further, in exposure apparatus 100, a multiple focal point position detection system (hereinafter appropriately referred to as a ‘multipoint AF system’) is arranged that is made up of an irradiation system 60A and a photodetection system 60B arranged sandwiching alignment system ALG. Irradiation system 60A has a light source which on/off is controlled by main controller 20, and irradiates a plurality of image-forming beams to form an image of a slit (or a pin hole) toward a surface of wafer W from an oblique direction with respect to optical axis AX in the case wafer W is located directly below alignment system ALG. Photodetection system 60B receives the image-forming beams reflected off the surface of wafer W. In other words, the multi point AF system is a focal point position detection system by an oblique incident method that detects the position of wafer W in the optical axis AX direction (the Z-axis direction) and the gradient of wafer W with respect to the XY plane. As the multipoint AF system (60A, 60B) in the embodiment, the configuration similar to the one disclosed in, for example, Kokai (Japanese Unexamined Patent Application Publication) No. 06-283403, and the corresponding U.S. Pat. No. 5,448,332, and the like is used. In the embodiment, however, the multipoint AF system is not arranged in the vicinity of projection optical system PL (further, so as to have the optical axis of the projection optical system as the center), but is arranged in the vicinity of alignment system ALG. As long as the national laws in designated states (or elected states), to which this international application is applied, permit, the above disclosures of the publication and the U.S. Patent are incorporated herein by reference.
In irradiation system 60A, for example, an illumination light source, a pattern plate where 64 slit-shaped aperture patterns in a matrix arrangement of 8 rows and 8 columns, as an example, are formed, an irradiation optical system and the like are arranged. In addition, in photodetection system 60B, a photodetection slit plate where 64 slits in total in a matrix arrangement of 8 rows and 8 columns, as an example, are formed, a focus sensor serving as a sensor that is made up of photodetection elements such as 64 photodiodes arranged in a matrix arrangement of 8 rows and 8 columns facing the respective slits of the slit plate, a rotation direction vibrating plate, a photodetection optical system and the like are arranged.
The operations of each part of the multipoint AF system (60A, 60B) will be briefly described next. When the pattern plate is illuminated by an illumination light from the illumination light source within irradiation system 60A under instructions from main controller 20, as is shown in
The S-curve signal is a signal that becomes a zero level when the slit center of the photodetection slit plate coincides with the vibration center of the reflection slit image from wafer W, becomes a plus level when wafer W is displaced upward from such a state, and becomes a minus level when wafer W is displaced downward. Accordingly, in a state where an offset is not added to the S-curve signal, the height positions of wafer W where the S-curve signal becomes a zero level are severally detected at each slit image by main controller 20.
Incidentally, in the following description, the place on wafer W where slit images S11 to S88 shown in
Referring back to
Next, based on
Prism 28A is to guide illumination light IL to a RA mark (e.g. RM1) on reticle R when prism 28A is located at the measurement position in
Fixed section 32A is composed including an image-forming optical system 35, a drive unit 41 that drives a focused-state adjustment lens 39 arranged within image-forming optical system 35, an imaging device (CCD) 42 and the like.
As image-forming optical system 35, in this case, an optical system that can change a focal distance by driving focused-state adjustment lens 39 arranged inside, that is, the so-called internal focusing optical system is used. Therefore, in the embodiment, main controller 20 obtains the contrast of light intensity signals corresponding to the projected images of the RA mark (e.g. RM1) and the first fiducial mark (e.g. WM1) on fiducial mark plate FM, for example, by processing the image signals in imaging device 42, and drives focused-state adjustment lens 39 in the optical axis direction via drive unit 41 so that the contrast reaches the peak, and therefore a focal point of image-forming optical system 35 can be focused on a pattern surface of reticle R and a photodetection surface of imaging device 42. That is, the focusing operations of image-forming optical system 35 can be performed.
As is shown in
Referring back to
Next, a series of exposure operations in exposure apparatus 100 in the embodiment will be described in detail. As is described above, in exposure apparatus 100 of the embodiment, measurement area MA of the multipoint AF system (60A, 60B) is not positioned in the optical axis of projection optical system PL but is positioned at the position corresponding to a detection field of alignment system ALG by the off-axis method, which is different from an exposure apparatus as disclosed in Kokai (Japanese Unexamined Patent Application Publication) No. 06-349701 and the like. In other words, in exposure apparatus 100 of the embodiment, because a measurement point surface of the multipoint AF system is not located in optical axis AX, autofocus leveling control cannot be performed while detecting a surface position of wafer W in real time during scanning exposure using the multipoint AF system. Therefore, in exposure apparatus 100 of the embodiment, when detecting wafer alignment marks in fine alignment, information related to a surface shape of a surface subject to exposure of wafer W is also detected using the multipoint AF system (60A, 60B), and during scanning exposure, autofocus leveling control of wafer W during the scanning exposure is performed using the information related to a surface shape of the surface subject to exposure of wafer W detected beforehand.
In the case the autofocus leveling control of wafer W during exposure is performed using the information related to a surface shape of the surface subject to exposure of wafer W detected beforehand, calibration related to a detection system that detects the information needs to be performed with good accuracy. Next, information to be detected in the calibration will be described.
Further, as is shown in
Further, in the multipoint AF system (60A, 60B), since the Z position at each of measurement points S11 to S88 is detected independently by a plurality of focus sensors, a deviation necessarily occurs in the detection origin of the Z-position at each measurement point. It is difficult to mechanically reduce the deviation in the detection origins of all focus sensors to zero, and thus, in the embodiment, the deviation in the detection origins is outputted as an offset component at each measurement point.
In other words, in the embodiment, calibration of the best image-forming plane of projection optical system PL and measurement area MA formed by the detection origins of a plurality of measurement points of the multipoint AF system (60A, 60B) needs to be performed, before exposure.
In the next step, step 303, reticle stage RST is aligned so that a center mark positioned at the center on reticle R1 (a measurement mark PM24 corresponding to a measurement point P24 shown in
In the next step, step 311, wafer stage WST is driven via wafer stage drive section WSC so that slit plate 90 is moved to a scanning starting position where slit scanning of an aerial image of measurement mark PMij (measurement mark PM11 in this case) can be performed. In the next step, step 313, aerial image measurement of measurement mark PMij (measurement mark PM11 in this case) is repeatedly performed using aerial image measurement unit 59 based on the slit-scan method by irradiating illumination light IL to reticle R1, while shifting the Z position of wafer stage WST in a predetermined step pitch. When performing the aerial image measurement at each Z position, the Z-position of wafer stage WST is controlled via wafer stage drive section WSC based on the Z position of wafer stage WST measured by wafer interferometer 18. Further, a gradient of slit plate 90, that is, a gradient of wafer stage WST with respect to the XY plane that is orthogonal to optical axis AX of projection optical system PL is controlled to be at a desired constant angle (for example, so that both the pitching and the rolling become zero), based on the measurement values of wafer interferometer 18, more accurately, the measurement values of a pair of a Y interferometer (serving as a pitching interferometer) and an X interferometer (serving as a rolling interferometer) that have a measurement axis for detecting the pitching and the rolling of wafer stage WST, respectively. Then, in the next step, step 315, a Z position Zij, at which the contrast curve related to the aerial image of measurement mark PMij that has been obtained based on the measurement results of the aerial image indicates a peak value, is computed, and position Zij is stored in an internal memory as the best focus position at an evaluation point Pij.
Incidentally, when the Z position of wafer stage WST is changed, the distance between tip lens 91 and wafer W also changes, and therefore, an amount of water Lq held in the space between them is also changed appropriately by liquid supply/drainage system 132.
In the next step, step 317, counter value j is incremented by one (j←j+1). Then, in the next step, step 319, the judgment is made of whether or not counter value j exceeds 7. In this case, since counter value j is 2, the judgment is denied and the procedure returns to step 309.
Afterward, until counter value j exceeds 7 and the judgment is affirmed in step 319, the processing and judgment of steps 309→311→313→315→317→319 are repeatedly executed, and the aerial image measurement of measurement marks PM12 to PM17 at measurement points P12 to P17 is performed at a plurality of Z positions, and best focus positions Z11 to Z17 at the measurement points are detected and stored in the internal memory.
When counter value j exceeds 7 and the judgment in step 319 is affirmed, the procedure proceeds to step 321. In step 321, counter value i is incremented by one (i←i+1). In the next step, step 323, the judgment is made of whether or not counter value i exceeds 3. In this case, since counter value i equals 2, the judgment is denied, and the procedure returns to step 307.
Afterward, until counter value i equals 4 and the judgment is affirmed in step 323, the processing and judgment of steps 307→309→311→313→315→317→319 are repeatedly executed, and the aerial image measurement of measurement marks PM21 to PM27 at measurement points P21 to P27 is performed at a plurality of Z positions, and best focus positions Z21 to Z27 at the measurement points are detected and stored in the internal memory. Then, the processing and judgment of steps 307→309→311→313→315→317→319 are repeatedly executed further one more time, and the aerial image measurement of measurement marks PM31 to PM37 at measurement points P31 to P37 is performed at a plurality of Z positions, and best focus positions Z31 to Z37 at the measurement points are detected and stored in the internal memory.
When counter value i becomes 4 and the judgment in step 323 is affirmed, the procedure proceeds to step 325. In step 325, an approximate plane of an image plane of projection optical system PL (and an image plane shape) is computed by performing a predetermined statistical processing based on best focus positions Z11, Z12, . . . , Z37 obtained in the above-described manner. On the computation, the field curvature can be computed separately from the image plane shape. Since the image plane of projection optical system PL, that is, the best image-forming plane is a plane made up of a group of best focus positions at a myriad of points which distances from the optical axis are different (that is, a myriad of points where the so-called heights of images are different), the image plane shape and the approximate plane of the image plane can be easily and accurately obtained in this manner.
In the next step, step 327, focusing of RA detection systems 12A and 12B is performed. First, as is shown in
Further, movable sections 33A and 33B of RA detection systems 12A and 12B shown in
In the next step, step 329, supply/drainage of water is stopped by liquid supply/drainage system 132. Accordingly, the water below tip lens 91 is removed. When step 329 is completed, the procedure proceeds to step 203 in
In the next step, step 203, wafer stage WST is moved via wafer stage drive section WSC so that slit plate 90 also serving as a datum plane plate as described above is positioned below alignment system ALG (that is, measurement area MA of the multipoint AF system). On this operation, a gradient of slit plate 90, that is, a gradient of wafer stage WST with respect to the XY plane orthogonal to optical axis AX of projection optical system PL is controlled to be at a desired constant angle (for example, so that both the pitching and the rolling become zero), based on the measurement values of wafer interferometer 18, more accurately, the measurement values of a pair of a Y interferometer (serving as a pitching interferometer) and an X interferometer (serving as a rolling interferometer) that have a measurement axis for detecting the pitching and the rolling of wafer stage WST, respectively. Further, main controller 20 adjusts the Z position of wafer stage WST to the position at which any measurement results of measurement points S11 to S88 (each measurement point on slit plate 90 in this case) that are measured by the multipoint AF system (60A, 60B) are not out of a measurement range and are not saturated.
In the next step, step 205, the measurement results of measurement point S11 to S88 are obtained, and the measurement results are stored in the internal memory as offset components D11 to D88 at measurement point S11 to S88 as is shown in
Incidentally, in the case the measurement points at which measurement results are saturated still exist even if the Z position of wafer stage WST is adjusted, an adjustment member composing the multipoint AF system (60A, 60B), for example, a rotation amount of a parallel plate glass may be adjusted.
In the next step, step 207, reticle replacement is performed. With this operation, reticle R1 held on reticle stage RST is unloaded by a reticle unloader (not shown), and reticle R to be used for actual exposure is loaded by a reticle loader (not shown).
In the next step, step 209, preparatory operations such as reticle alignment and baseline measurement are performed in the same procedures as in the normal scanning stepper, using the reticle alignment systems (12A, 12B), fiducial mark plate FM and the like. Incidentally, of the preparatory operations, the reticle alignment is performed in a state where water Lq is supplied in the space between tip lens 91 and fiducial mark plate FM by liquid supply/drainage system 132. After the reticle alignment, supply/drainage of water is stopped.
In the next step, step 211, wafer stage WST is moved to a loading position, and wafer W is loaded on wafer stage WST by a wafer loader (not shown). In the next step, step 213, search alignment is performed. With regard to the search alignment, the method similar to the one whose details are disclosed in, for example, Kokai (Japanese Unexamined Patent Application Publication) No. 02-272305 and the corresponding U.S. Pat. No. 5,151,750, and the like is used. As long as the national laws in designated states (or elected states), to which this international application is applied, permit, the above disclosures of the publication and the U.S. Patent are incorporated herein by reference.
In the next step, step 215, wafer stage WST is moved to directly below alignment system ALG, and wafer alignment (fine alignment) is performed to wafer W on wafer stage WST. In this case, as an example, the wafer alignment based on the EGA (Enhanced Global Alignment) method, which details are disclosed in, for example, Kokai (Japanese Unexamined Patent Application Publication) No. 61-044429 and the corresponding U.S. Pat. No. 4,780,617, and the like, is performed. As long as the national laws in designated states (or elected states), to which this international application is applied, permit, the above disclosures of the publication and the U.S. Patent are incorporated herein by reference.
In the wafer alignment, among shot areas SA on wafer W represented by a solid line frame in
Incidentally, in the wafer alignment, wafer stage WST is moved in the XY plane and the wafer alignment mark arranged in each sample shot area is sequentially moved into the detection field of alignment system ALG, and then the wafer alignment mark is detected. In other words, when the wafer alignment marks arranged in all sample shot areas are detected, the detection field of alignment system ALG sequentially moves to 14 sample shot areas in a predetermined route. In
Then, in step 215, the wafer alignment marks arranged in the sample shot areas are detected by alignment system ALG, and also the Z position of the surface (the surface position) of wafer W is measured by the multipoint AF system (60A, 60B). That is, every time when the detection field of alignment system ALG moves to in the vicinity of each sample shot, the Z positions at measurement points S11 to S88 within the measurement area of the multipoint AM system, as is shown by the dotted line frame in
Incidentally, the detection origins of measurement points S11 to S88 of the multipoint AF system (60A, 60B) have the deviation as is described earlier, and therefore offset components D11 to D88 obtained in the above step 205 need to be canceled from the measurement value of the Z position at each measurement point.
As is described above, in the wafer alignment in step 215, the Z position of the surface subject to exposure of wafer W is measured by the multipoint AF system (60A, 60B) together with measurement of the wafer alignment marks. From this Z position and the measurement value of wafer interferometer 18 at the time of measuring the Z-position (position information within the XY plane of wafer stage WST and position information in the Z-axis direction), information related to a surface shape of the surface subject to exposure of wafer W can be obtained. In the following description, the information is called as a Z map, and a processing for obtaining the Z map is called as a Z mapping. Incidentally, because the Z map is data that is discrete with regard to the XY plane, a continuous function that shows information related to a surface shape of the surface subject to exposure of wafer W may be made by a predetermined interpolation computation, a statistical computation or the like.
In the next step, step 217, an arrangement coordinate of shot areas on wafer W is computed based on the results of the wafer alignment by the EGA method detected in the above step 215. Then, in the next step, step 219, a position order profile in six degrees of freedom of the XYZ coordinate system of wafer stage WST during scanning exposure is made based on the arrangement coordinate, the Z map and the baseline measurement results in the above step 209. In this case, when making the position order profile that contributes to the autofocus leveling control based on the Z map made in the above step 215, it is a matter of course that deviation ΔZ between the Z axis and the Z′ axis as shown in
In the next step, step 221, scanning exposure is performed to a plurality of shot areas on wafer W. Specifically, wafer W (wafer stage WST) is moved to an acceleration starting position for exposure of a first shot area (a first shot) based on the position order profile in six degrees of freedom of the XYZ coordinate system of wafer stage WST that is made in the above step 219, and at the same time, reticle R (reticle stage RST) is moved to an acceleration starting position. Then, liquid supply/drainage system 132 starts supply/drainage of water Lq to the space between tip lens 91 and wafer W. Then, based on the position order profile made in the above step 219, relative scanning (synchronous movement) of wafer W (wafer stage WST) and reticle R (reticle stage RST) in the Y-axis direction is started, and the scanning exposure is performed to the first shot on wafer W. By this operation, a circuit pattern of reticle R is sequentially transferred to the first shot on wafer W via projection optical system PL.
During the scanning exposure described above, in order to make exposure area IA on a surface of wafer W substantially conform to the best image-forming plane of projection optical system PL (be positioned within the range of depth of focus of the image-forming plane), by driving wafer stage WST in the Z-axis direction, the θx direction, and the θz direction via wafer stage drive section WSC based on the XY plane position and the Z position of wafer stage WST that are measured by wafer interferometer 18 and the Z map detected in step 215, the open-loop focus leveling control to wafer W is achieved.
Then, when the scanning exposure operations to the first shot are completed, main controller 20 moves wafer stage WST so that wafer W is positioned at an acceleration starting position for exposure to a second shot area (a second shot) on wafer W. In this case, since a complete alternate scanning method is employed, reticle stage RST moves to an acceleration starting position for performing exposure to the next shot area at the time when a series of operations for scanning exposure to the previous shot area is completed.
Main controller 20 then starts the relative scanning of reticle stage RST and wafer stage WST and performs the scanning exposure in the same manner as described earlier to sequentially transfer a pattern of reticle R to the second shot on wafer W via projection optical system PL, and during the transferring, the same open-loop focus leveling control is executed to wafer W as is described earlier.
Afterward, the movement of wafer stage WST (a stepping operation between shots) and the scanning exposure in the same manner as described above are repeatedly performed, and a pattern of reticle R is transferred to the third and succeeding shot areas on wafer W.
After the scanning exposure to all shot areas on wafer W is completed in this manner, the supply/drainage of water Lq by liquid supply/drainage system 132 is stopped, and in step 223, wafer stage WST is moved to an unloading position and wafer W is unloaded by a wafer unloader (not shown). After step 223 ends, the processing is completed.
Incidentally, in the embodiment, after the best focus position of projection optical system PL is detected, the offset component of the multipoint AF system (60A, 60B) is detected, however, the order may be reversed. Further, the search alignment does not have to be performed. In addition, the number of sample shots in the fine alignment is not limited to 14, and for example, may be 8. In that case, the surface position detection of wafer W is to be performed in area MA as is shown in
Further, in the case wafer W is a bare wafer, the search alignment in step 213 and the fine alignment in step 215 (and further, the arrangement coordinate computation in step 217) are not performed, however, the surface position detection of wafer W needs to be performed by the multipoint AF system.
As is obvious from the description so far, in exposure apparatus 100 of the embodiment, at least a part of a stage is composed of wafer stage WST and at least a part of a first position detection unit and a second position detection unit is composed of wafer interferometer 18. A surface shape detection system is composed including apart of the multipoint AF system (60A, 60B) and main controller 20, and an adjustment unit is composed including a part of main controller 20. In addition, a measurement unit is composed including a part of main controller 20. Further, a focal point position detection system is composed including the multipoint AF system (60A, 60B). Further, a detection mechanism is composed including the RA detection system (12A, 12B).
In other words, a part of the function of the surface shape detection system is achieved by the processing in step 215 (
As is described in detail above, in exposure apparatus 100 of the embodiment, the information (Z map) related to a surface shape of the surface subject to exposure of wafer W held by wafer stage WST is detected by the surface shape detection system (the multipoint AF system (60A, 60B), a part of main controller 20) prior to projection exposure, and when the projection exposure is performed, a surface position of wafer W on wafer stage WST is adjusted by main controller 20 based on the information (the Z map) related to the surface shape of the surface subject to exposure detected by the surface shape detection system. Therefore, when performing the projection exposure, exposure area IA on wafer W during scanning exposure can be positioned within a range of depth of focus of the best image-forming plane of projection optical system PL, without detecting in real time the position of wafer W in a direction of optical axis AX of projection optical system PL, which makes it possible to achieve exposure with high precision by the projection optical system having large numerical aperture.
Further, in the embodiment, main controller 20 detects the best image-forming plane by measuring the best focus position of projection optical system PL and adjusts a surface position of the surface subject to exposure of wafer W using the best image-forming plane as a datum. However, the best image-forming plane of projection optical system PL does not need to be obtained when it is ensured that the best image-forming plane of projection optical system PL is substantially parallel to the XY plane, and the best focus position at any one measurement point (for example, on the optical axis) within the effective exposure field only has to be obtained. In addition, the distance between measurement points P11 to P37 and the number of the measurement points are not limited to those in the embodiment described above.
Further, in the embodiment, the best focus position of projection optical system PL is obtained by the aerial image measurement of aerial image measurement unit 59. However, the present invention is not limited to this, and the detection method of the best focus position may be any method. For example, a predetermined pattern is actually exposed on wafer W at a plurality of Z positions, and the Z position where the exposure result is best may be determined as the best focus position. In this case, the exposure apparatus does not need to be equipped with the aerial image measurement unit.
Further, in the embodiment described above, the center of measurement area MA of the multipoint AF system (60A, 60B) is made coincident with the center of the detection field of alignment system ALG, however, it is not always necessary to do so. In the case detection of the wafer alignment mark by alignment system ALG and detection of a surface position of wafer W by the multipoint AF system (60A, 60B) are not simultaneously performed, alignment system ALG and the multipoint AF system may be arranged separately. However, when alignment system ALG and the multipoint AF system are arranged as in the embodiment above, the detection of the wafer alignment mark and the detection of a surface position of wafer W can be performed at the same time, which is advantageous in regard to throughput.
Further, in the embodiment described above, the number of measurement points of the multipoint AF system (60A, 60B) is 8×8=64 points, however, it is a matter of course that the number is not limited to 64. In addition, a size of measurement area MA, a size and a direction of each measurement point are not limited to those in the embodiment above. For example, the distance between the measurement points may be the same as the distance between the measurement points (X: 4 mm, Y: 3.5 mm) at which the best focus position of projection optical system PL is measured. In addition, in the embodiment above, a detection system that detects a surface position of wafer W is the multipoint AF system (60A, 60B), however, the detection system does not need to be the multipoint AF system. For example, the detection system may be a detection system that detects the Z position at only one point of wafer W. In this case, since an offset component of the detection system cannot be considered, the offset component does not need to be detected as in the above step 205, and ΔZ as shown in
Further, in the embodiment described above, when detecting the information (the Z map) related to a surface shape of the surface subject to exposure of wafer W using the multipoint AF system (60A, 60B), the Z position of wafer stage WST at the time of the detection is measured by wafer interferometer 18, and based on the measurement results, the surface of wafer W which shape is detected is made to conform to the best image-forming plane of projection optical system PL within a range of depth of focus. In this manner, as exposure apparatus 100 shown in
However, the configuration of an exposure apparatus is not limited to the one in the embodiment above. For example, in an exposure apparatus that is not equipped with wafer interferometer 18 as shown in
In such a case, the Z position may be aligned using the RA detection systems (12A, 12B). In the following description, the alignment method will be described.
For example, when performing the Z mapping in the above step 215, along with a surface shape of the surface subject to exposure of wafer W, a surface position of fiducial mark plate FM is also measured using the multipoint AF system (60A, 60B), and stored in the internal memory. Then, in the case wafer stage WST is moved to below projection optical system PL in order to perform exposure to wafer W on wafer stage WST, first fiducial mark WM1 and WM2 on fiducial mark plate FM are detected by the RA detection system (12A, 12B). Main controller 20 drives wafer stage WST in the Z-axis direction, and finds the Z position where the contrast of light intensity signals by the RA detection system (12A, 12B) corresponding to the first fiducial marks reaches the peak. On the assumption that the focusing operations in the above step 327 have been already performed in the RA detection system (12A, 12B) at this point of time and a surface position of fiducial mark plate FM is set so as to conform to the best image-forming plane of projection optical system PL, this position is to correspond to the best focus position of the projection optical system. Accordingly, in this manner, the Z position of the surface subject to exposure of wafer W at present can be grasped from a relative positional relation between the surface position of fiducial mark plate FM and the surface position of the surface subject to exposure of wafer W. Therefore, as in the embodiment above, the surface subject to exposure of wafer W can be made to conform to the best image-forming plane of projection optical system PL within a range of depth of focus, during scanning exposure.
Incidentally, the best image-forming plane of projection optical system PL (the best focus position) does not necessarily have to be made to conform to the best focus position of the RA detection system (12A, 12B) or the like. The deviation between them in the Z-axis direction only has to be known. This is because when fiducial mark plate FM can be positioned at the best focus position of the RA detection system (12A, 12B) by detecting fiducial mark plate FM by the RA detection system (12A, 12B), the relative positional relation between the fiducial mark plate FM and the best image-forming plane of projection optical system PL at this point of time can be determined, and therefore the best image-forming plane of projection optical system PL can be made to conform to the surface subject to exposure of wafer W within a range of depth of focus. Thus, the RA detection system does not necessarily have to be equipped with the focusing unit as in the embodiment.
However, in this case, calibration of the positional relation between the best image-forming plane of projection optical system PL and the best focus position of the RA detection system needs to be performed in advance. The best image-forming plane of projection optical system PL can be obtained in the same method as in the embodiment described above. Meanwhile, the best focus position of the RA detection system can also be obtained from the contrast curve in the Z-axis direction of the detection results of the first fiducial marks on fiducial mark plate FM, and the like.
As is described above, when detecting a surface shape of the surface subject to exposure of wafer W, an absolute Z position of a surface of wafer W only has to be obtained. However, the exposure surface of wafer W can be made to conform to the best image-forming plane of projection optical system PL by only obtaining a relative Z position of the surface of wafer W with respect to a datum plane on wafer stage WST.
Incidentally, the RA detection system does not necessarily have to be used in detection of the Z position of fiducial mark plate FM. The point is that a relation between the surface of fiducial mark plate FM and the best image-forming plane of projection optical system PL only has to be obtained and another detection system that can detect the surface position of fiducial mark plate FM via projection optical system PL may be used, or the surface position of fiducial mark plate FM may be detected using a non-optical detection system such as a capacitance sensor without water. Further, another datum plane may be arranged on wafer stage WST and used, without using fiducial mark plate FM.
Further, in the embodiment described above, information related to the surface shape of the surface subject to exposure of wafer W is detected using the multipoint AF system (60A, 60B) that has a similar configuration to a multipoint AF system disclosed in Kokai (Japanese Unexamined Patent Application Publication) No. 06-283403 and has a measurement area whose center coincides with the center of the detection field of alignment system ALG, however, the present invention is not limited to this. For example, a surface shape detection unit as shown in
In actual, the line-shaped beam irradiated from irradiation system 75A is formed by a plurality of point-like (or slit-like) laser beams that are parallel to each other and are arranged in one direction, and irradiation area SL actually is, as is shown in
The measurement results of photodetection system 75B are sent to main controller 20. Main controller 20 detects information related to a surface shape of the surface subject to exposure of wafer W based on the measurement results, that is, the position deviation amount of the photodetection position of the reflected beam in photodetection system 75B from the datum position.
Irradiation area SL is arranged so as to make column of measurement points S1 to Sn intersect with the X-axis and the Y-axis as is shown in
Incidentally, the arrangement of measurement points S1 to Sn is not limited to the above example, and the measurement points may be arranged parallel to the X axis or the Y axis. Further, the measurement of the surface shape of wafer W using measurement points S1 to Sn is not necessarily performed between the measurement operations of the wafer alignment mark and the wafer exposure operations, and for example, may be performed before the measurement of the wafer alignment mark. The point is that wafer W has to be relatively scanned with respect to irradiation area SL before exposure of wafer W.
Alternatively, the exposure apparatus may be equipped with a surface shape detection unit having a configuration as is shown in
However, the configuration of the interferometer for measuring a surface shape of the surface subject to exposure of wafer W is not limited to the one as shown in
Incidentally, the arrangement of the surface shape detection unit as is shown in
Further, in the embodiment above, the movable mirror for Z position measurement arranged on wafer stage WST is only movable mirror 17Z arranged in the −X end. However, the movable mirror is not limited to this, and a movable mirror similar to movable mirror 17Z is also arranged in the +X end of wafer stage WST to irradiate the measurement beam also from the X side, and the Z position of wafer stage WST maybe obtained from the measurement results of the Z positions on both sides (for example, the average of the results). In this manner, the Z position of wafer stage WST can be measured with good accuracy regardless of the rolling of wafer stage WST.
Further, the movable mirror in the Z-axis direction is not limited to movable mirror 17Z as shown in the drawings such as
In addition, in the embodiment above, wafer interferometer 18 that can measure the position within the XY plane and the Z position of wafer stage WST is used, however, it is a matter of course that an interferometer that can measure the position within the XY plane and an interferometer that can measure the Z position are separately arranged.
In addition, the movable mirror for Z position measurement does not have to be arranged on a side surface of wafer stage WST and may be integrated with the movable mirror for XY position measurement. Alternatively, a movable mirror is arranged on a bottom surface of wafer stage WST and the Z position of wafer stage WST maybe measured by irradiating the measurement beam from the −Z side of wafer stage WST.
Incidentally, in the embodiment above, ultra pure water (water) is used as the liquid, however, as a matter of course, the present invention is not limited to this. As the liquid, a liquid that is chemically stable, having high transmittance to illumination light IL and safe to use, such as a fluorine-containing inert liquid may be used. As such a fluorine-containing inert liquid, for example, Fluorinert (the brand name of 3M United States) can be used. The fluorine-containing inert liquid is also excellent from the point of cooling effect. Further, as the liquid, a liquid which has high transmittance to illumination light IL and a refractive index as high as possible, and furthermore, a liquid which is stable against the projection optical system and the photoresist coated on the surface of the wafer (for example, cedarwood oil or the like) can also be used. Further, in the case the F2 laser is used as the light source, fomblin oil may be selected.
Further, in the embodiment above, the liquid that was recovered may be reused, and in this case, it is preferable to arrange a filter for removing impurities from the recovered liquid in the liquid recovery unit, the recovery pipes, or the like.
Incidentally, in the embodiment above, the optical element of projection optical system PL closest to the image plane side is tip lens 91. The optical element, however, is not limited to the lens, and it may be an optical plate (such as a parallel plane plate) used for adjusting the optical properties of projection optical system PL, for example, aberration (such as spherical aberration or coma), or it may simply be a cover glass. The surface of the optical element of projection optical system PL closest to the image plane side (tip lens 91 in the embodiment above) may be contaminated by coming into contact with the liquid (water, in the embodiment above) due to scattered particles generated from the resist by the irradiation of illumination light IL or adherence of impurities in the liquid. Therefore, the optical element is to be fixed freely detachable (exchangeable) in the lowest section of barrel 40, and may be exchanged periodically.
In such a case, when the optical element that comes into contact with the liquid is the lens, the cost for replacement parts is high, and the time required for exchange becomes long, which leads to an increase in the maintenance cost (running cost) as well as a decrease in throughput. Therefore, the optical element that comes into contact with the liquid may be, for example, a parallel plane plate, which is less costly than tip lens 91.
Further, in the embodiment above, the range of the liquid (water) flow only has to be set so that it covers the entire projection area (the irradiation area of illumination light IL) of the pattern image of the reticle. Therefore, the size may be of any size, however, on controlling the flow speed, the flow amount and the like, it is preferable to keep the range slightly larger than the irradiation area but as small as possible.
Incidentally, the projection optical system made up of a plurality of lenses and projection unit PU are incorporated into the main body of the exposure apparatus, and furthermore liquid supply/drainage unit 132 is attached to projection unit PU. Then, along with the optical adjustment operation, the reticle stage and the wafer stage that are made up of multiple mechanical parts are also attached to the main body of the exposure apparatus and the wiring and piping are connected. And then, total adjustment (such as electrical adjustment and operation check) is performed, which completes the making of the exposure apparatus of the embodiment above. The exposure apparatus is preferably built in a clean room where conditions such as the temperature and the degree of cleanliness are controlled.
Further, in the embodiment above, the case has been described where the present invention is applied to a scanning exposure apparatus by the step-and-scan method or the like, however, it is a matter of course that the present invention is not limited to this. In other words, the present invention can also be suitably applied to a reduction projection exposure apparatus by the step-and-repeat method. Further, the present invention can also be suitably applied to exposure in a reduction projection exposure apparatus by the step-and-stitch method in which shot areas are synthesized. Further, the present invention can also be applied to a twin-stage type exposure apparatus that is equipped with two wafer stages. Furthermore, it is a matter of course that the present invention can also be applied to an exposure apparatus that does not use the immersion method.
The usage of the exposure apparatus is not limited to the exposure apparatus used for manufacturing semiconductor devices. The present invention can be widely applied to, for example, an exposure apparatus for manufacturing liquid crystal displays which transfers a liquid crystal display deice pattern onto a square shaped glass plate, and to an exposure apparatus for manufacturing organic EL, thin-film magnetic heads, imaging devices (such as CCDs), micromachines, DNA chips or the like. Further, the present invention can also be applied to an exposure apparatus that transfers a circuit pattern onto a glass substrate or a silicon wafer not only when producing microdevices such as semiconductors, but also when producing a reticle or a mask used in an exposure apparatus such as an optical exposure apparatus, an EUV exposure apparatus, an X-ray exposure apparatus, or an electron beam exposure apparatus.
Further, the light source of the exposure apparatus in the embodiment above is not limited to the ArF excimer laser light source, and a pulsed laser light source such as a KrF excimer laser light source or an F2 laser light source, or an ultra high-pressure mercury lamp that generates a bright line such as the g-line (wavelength 436 nm) or the i-line (wavelength 365 nm) can also be used. Further, a harmonic wave may also be used that is obtained by amplifying a single-wavelength laser beam in the infrared or visible range emitted by a DFB semiconductor laser or fiber laser, with a fiber amplifier doped with, for example, erbium (or both erbium and ytteribium), and by converting the wavelength into ultraviolet light using a nonlinear optical crystal. Further, the magnification of the projection optical system is not limited to a reduction system, and the system may be either an equal magnifying system or a magnifying system.
Further, in the embodiment above, illumination light IL of the exposure apparatus is not limited the light having the wavelength equal to or greater than 100 nm, and it is needless to say that the light having the wavelength less than 100 nm may be used. For example, in recent years, in order to expose a pattern equal to or less than 70 nm, an EUV exposure apparatus that makes an SOR or a plasma laser as a light source generate an EUV (Extreme Ultraviolet) light in a soft X-ray range (such as a wavelength range from 5 to 15 nm), and uses a total reflection reduction optical system designed under the exposure wavelength (such as 13.5 nm) and the reflective type mask has been developed. In the EUV exposure apparatus, the arrangement in which scanning exposure is performed by synchronously scanning a mask and a wafer using a circular arc illumination can be considered.
Further, the present invention can be applied to an exposure apparatus that uses charged particle beams such as an electron beam or an ion beam. Incidentally, an electron beam exposure apparatus may employ any of the pencil beam method, variable beam shaping method, self projection method, blanking aperture array method, and mask projection method. For example, in an exposure apparatus that uses an electron beam, an optical system equipped with an electromagnetic lens constitutes an exposure optical system and an exposure optical system unit is configured including a barrel of the exposure optical system and the like.
[Device Manufacturing Method]
Next, an embodiment will be described of a device manufacturing method that uses exposure apparatus 100 described above in the lithography process.
Next, in step 804 (wafer processing step), the actual circuit and the like are formed on the wafer by lithography or the like in a manner that will be described later, using the mask and the wafer prepared in steps 801 to 803. Then, in step 805 (device assembly step), device assembly is performed using the wafer processed in step 804. Step 805 includes processes such as the dicing process, the bonding process, and the packaging process (chip encapsulation), when necessary.
Finally, in step 806 (inspection step), tests on operation, durability, and the like are performed on the devices made in step 805. After these steps, the devices are completed and shipped out.
When the above-described pre-process ends in each stage of wafer processing, post-process is executed as follows. In the post-process, first in step 815 (resist formation step), a photosensitive agent is coated on the wafer as is described in the embodiment above. Then, in step 816 (exposure step), the circuit pattern of the mask is transferred onto the wafer using exposure apparatus 100 in the embodiment described above. Next, in step 817 (development step), the exposed wafer is developed, and in step 818 (etching step), an exposed member of an area other than the area where resist remains is removed by etching. Then, in step 819 (resist removing step), when etching is completed, the resist that is no longer necessary is removed.
By repeatedly performing the pre-process and the post-process, circuit patterns are hierarchically formed on the wafer.
When the above device manufacturing method of the embodiment described above is used, because exposure apparatus 100 and the exposure method of the embodiment above are used in the exposure process (step 816), exposure with good precision can be achieved. As a consequence, the productivity (including the yield) of high integration devices can be improved.
As is described above, the exposure apparatus and the exposure method of the present invention is suitable to a lithography process for manufacturing semiconductor devices, liquid crystal display devices, or the like, and the device manufacturing method of the present invention is suitable for producing microdevices. Further, the surface shape detection unit of the present invention is suitable for detecting a surface shape of a substrate to be exposed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-099530 | Mar 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/06071 | 3/30/2005 | WO | 9/28/2006 |
