JP2004301825A - Surface position detection device, exposure method and method for manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface position detection device that can precisely detect surface position information of a surface to be detected even when a refractive index of a detection light for surface position detection on an optical path changes. <P>SOLUTION: The surface position detection device 100 is provided with a light projection system 8 to project detection light onto a surface S to be detected and a light receiving system 9 to receive light reflected on the surface S, and it detects a surface position information of the surface S on the basis of information acquired by the light receiving system 9. A plurality of beams of light L1 and L2 are projected as detection light onto the surface S at incident angles θ<SB>1</SB>and θ<SB>2</SB>respectively. Even if the refractive index of a medium on the surface S changes due to temperature change, the surface position information can be corrected based on the beams of reflection light of the lights L1 and L2. The surface position detector 100 is useful for an immersion aligner. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface position detecting device for optically detecting surface position information of a surface to be inspected, an exposure method for exposing a mask pattern image on a substrate, and a device manufacturing method.

  A semiconductor device and a liquid crystal display device are manufactured by a so-called photolithography technique of transferring a pattern formed on a mask onto a photosensitive substrate. The exposure apparatus used in this photolithography process has a mask stage that supports a mask and a substrate stage that supports a substrate, and sequentially moves the mask stage and the substrate stage to project a pattern of the mask through a projection optical system. This is to be transferred to a substrate. The exposure apparatus is provided with an autofocus detection system that detects surface position information of the substrate surface in order to align the substrate surface with the image plane of the projection optical system. As an autofocus detection system (AF detection system), there is an oblique incidence system as disclosed in, for example, JP-A-6-66543. In this method, focus detection light is applied to the substrate surface from an oblique direction, and positional information on the substrate surface is detected by light reflected on the substrate surface. In the oblique incidence type AF detection system, as shown in the schematic diagram of FIG. 10A, when the surface of the substrate P, which is the surface to be inspected, moves in the vertical direction, for example, as indicated by the symbol P ′, the irradiated AF detection system is detected. Since the reflected light of the light L on the substrate surface is shifted in the direction perpendicular to the optical axis of the optical system constituting the AF detection system, by detecting the amount of shift Da, the surface position of the substrate surface in the optical axis direction of the projection optical system is detected. Information can be detected.

By the way, in order to cope with higher integration of device patterns, further higher resolution of the projection optical system is desired. The resolution of the projection optical system increases as the exposure wavelength used decreases and as the numerical aperture of the projection optical system increases. For this reason, the exposure wavelength used in the exposure apparatus is becoming shorter year by year, and the numerical aperture of the projection optical system is also increasing. The exposure wavelength currently mainstream is 248 nm of KrF excimer laser, but 193 nm of shorter wavelength ArF excimer laser is also being put to practical use. When performing exposure, the depth of focus (DOF) becomes important as well as the resolution. The resolution R and the depth of focus δ are respectively represented by the following equations.
R = k ₁ · λ / NA (1)
δ = ± k ₂ · λ / NA ² (2)
Here, λ is the exposure wavelength, NA is the numerical aperture of the projection optical system, and k ₁ and k ₂ are the process coefficients. From the expressions (1) and (2), it can be seen that when the exposure wavelength λ is shortened and the numerical aperture NA is increased in order to increase the resolution R, the depth of focus δ becomes narrower.

If the depth of focus δ becomes too narrow, it becomes difficult to match the substrate surface with the image plane of the projection optical system, and the focus margin during the exposure operation may be insufficient. Therefore, as a method of substantially shortening the exposure wavelength and widening the depth of focus, for example, a liquid immersion method disclosed in International Publication WO99 / 49504 has been proposed. In this immersion method, the space between the lower surface of the projection optical system and the substrate surface is filled with a liquid such as water or an organic solvent, and the wavelength of the exposure light in the liquid is 1 / n (n is the refraction of the liquid) in the air. The ratio is usually about 1.2 to 1.6), thereby improving the resolution and expanding the depth of focus to about n times.
JP-A-6-66543 WO 99/49504 pamphlet

  By the way, in a case where the liquid is filled between the lower surface of the projection optical system and the surface of the substrate, when the surface position information of the substrate surface is to be obtained by the oblique incidence type AF detection system as described above, for example, when the temperature is changed, etc. When the refractive index of the liquid changes due to this, the incident angle of the detection light L with respect to the surface of the substrate P was θ before the change in the refractive index, as shown in the schematic diagram of FIG. After the change, there is an inconvenience of a change like θ ′. If the incident angle changes, the optical paths of the detection light L and the light reflected by the substrate P deviate from the optical paths before the change in the refractive index, so that the light-receiving surface of the AF detection system does not change even if the position of the substrate surface has not changed. The position of the detection light L (reflected light on the surface of the substrate) incident on the substrate is shifted, and the AF detection system erroneously determines that the position of the substrate has changed. As a result, the surface position of the substrate surface may not be measured with high accuracy.

  The present invention has been made in view of such circumstances, and a surface position detection device capable of accurately detecting surface position information on a substrate surface even when a refractive index on an optical path of detection light of an AF detection system changes. The primary purpose is to provide. It is a second object of the present invention to provide an exposure method and a device manufacturing method that can accurately detect substrate surface position information and manufacture a device even if the refractive index of the detection light on the optical path of the AF detection system changes. . In addition, the present invention provides an exposure method that can form a pattern image on a substrate with high accuracy even when using an immersion exposure method in which a pattern image is projected onto the substrate via a liquid between a projection optical system and the substrate. This is the third purpose. In particular, a fourth object is to provide an exposure method capable of forming a pattern image on a substrate with high accuracy even when the temperature of the liquid changes.

  In order to solve the above-described problem, the present invention employs the following configuration corresponding to FIGS. However, the parenthesized code given to each element is only an example of the element, and there is no intention to limit each element.

According to the first aspect of the present invention, the detection light is projected on the test surface (S), and the detection light is reflected based on the information obtained by receiving the reflected light from the test surface (S). a surface position detecting apparatus for detecting a surface position of the surface (S), projected as the detection light, a plurality of light (L1, L2) of different angles of incidence (θ _1, θ ₂₎ on the test surface (S) with And a light receiving system (9) for receiving reflected light from the surface to be detected (S).

According to a second aspect of the present invention, there is provided an exposure method for projecting an image of a pattern of a mask (M) onto a substrate (P) by a projection optical system (PL) and exposing the substrate (P). Te: a plurality of detection light on the plate surface (S) (L1, L2) of different angles of incidence (θ _1, θ ₂₎ with projecting at, for receiving reflected light from the substrate surface (S) (L1r, L2r) In this way, the refractive index information of the optical path of the detection light (L1, L2) and the reflected light (L1r, L2r) is detected; and the image of the pattern of the mask (M) is projected onto the substrate (P) by the projection optical system (PL). Exposure method is provided.

  According to the present invention, even when the refractive index on the optical path of the detection light changes, by projecting a plurality of lights as detection light at different incident angles on the surface to be detected, surface position information based on each of these detection lights is obtained. Since each shows a different measurement error (error amount), the refractive index change amount on the optical path can be obtained based on the difference (difference) between these error amounts. Since the detected surface position information can be corrected based on the obtained refractive index change amount, the surface position information of the test surface can be obtained with high accuracy. In order to project a plurality of lights on the surface to be inspected at different incident angles, for example, a plurality of light sources and an optical system may be used. Alternatively, a wavelength tunable laser or a light source having a plurality of wavelengths is used together with a wavelength selection filter, an etalon, a spectroscope, a prism, and the like to change an optical path for each wavelength of light so that an incident angle on a surface to be measured is different. You may. Alternatively, the optical path may be split or deflected using a pupil splitter or a galvanomirror.

  According to the third aspect of the present invention, the detection light is projected on the test surface (S), and the detection target is detected based on information obtained by receiving the reflected light from the test surface (S). A surface position detection device for detecting a surface position of a surface (S), comprising: a light transmission system (8) for projecting a plurality of lights having different wavelengths as detection light onto a surface (S) to be detected; And a light receiving system (9) for receiving the reflected light from S).

  According to a fourth aspect of the present invention, there is provided an exposure method for projecting an image of a pattern of a mask (M) onto a substrate (P) by a projection optical system (PL) and exposing the substrate (P). T: Detecting the refractive index information of the detection light and the optical path of the reflected light by projecting a plurality of detection lights having different wavelengths on the substrate surface (S) and receiving the reflected light from the substrate surface (S). And projecting an image of the pattern of the mask (M) onto the substrate (P) via the projection optical system (PL).

  According to the present invention, by utilizing the fact that each of the refraction angles when light having different wavelengths is incident on an object shows different values, and by projecting a plurality of detection lights having different wavelengths, on the surface to be measured. On the other hand, the detection light can be irradiated at mutually different incident angles.

  In this case, the detection light is projected on the surface to be detected via the light transmitting member. Examples of the light transmitting member include an optical element constituting a projection optical system, and a light transmitting parallel flat plate disposed between the projection optical system and the surface to be inspected. In particular, even in the case of performing the exposure process by the liquid immersion method, since the surface position of the substrate surface can be detected with high accuracy via the liquid, pattern transfer can be performed with high resolution.

  According to a fifth aspect of the present invention, an image of a pattern is projected onto a substrate (P) by a projection optical system (PL) via a liquid (50), and the substrate (P) is subjected to immersion exposure. An exposure method, wherein at least a part between the projection optical system (PL) and the substrate (P) is filled with a liquid (50); and a liquid between the projection optical system (PL) and the substrate (P). An exposure method is provided, comprising: optically detecting the temperature information of (50); and projecting an image of a pattern onto a substrate (P) via a liquid (50) by a projection optical system (PL). You.

  According to the present invention, by detecting temperature information (temperature change) of a liquid between a projection optical system and a substrate, detection of a surface position of a substrate surface performed through the liquid and formation of the liquid through the liquid are performed. The influence on the pattern image to be performed can be grasped, and for example, the image adjustment can be performed based on the detected temperature information.

  Even if the refractive index on the optical path of the detection light changes, by projecting a plurality of lights as detection light at different incident angles on the surface to be detected, each of the surface position information based on each of the detection lights has a different measurement error. Therefore, the refractive index information on the optical path can be obtained based on the difference between these measurement errors. Therefore, the detected surface position information can be corrected with the obtained refractive index information, so that the surface position information of the test surface can be obtained with high accuracy.

  Hereinafter, the surface position detecting device and the exposure method of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. FIG. 1 is a schematic configuration diagram showing an embodiment of an exposure apparatus equipped with an autofocus detection device as a surface position detection device of the present invention.

  1, an exposure apparatus EX includes a mask stage MST that supports a mask M, a substrate stage PST that supports a substrate P, and an illumination optical system IL that illuminates the mask M supported by the mask stage MST with exposure light EL. A projection optical system PL for projecting and exposing an image of the pattern of the mask M illuminated by the exposure light EL onto a substrate P supported on a substrate stage PST, and surface position information of a surface S of the substrate P as a surface to be inspected An auto-focus detection device 100 as a surface position detection device for detecting an image, and a control device CONT for controlling the overall operation of the exposure apparatus EX.

  Here, in the present embodiment, the exposure apparatus EX scans the mask M and the substrate P synchronously in directions different from each other in the scanning direction (opposite directions) while exposing the pattern formed on the mask M to the substrate P. An example in which an apparatus (a so-called scanning stepper) is used will be described. In the following description, the direction that coincides with the optical axis AX of the projection optical system PL is the Z-axis direction, the synchronous movement direction (scanning direction) between the mask M and the substrate P in a plane perpendicular to the Z-axis direction is the X-axis direction, A direction perpendicular to the Z-axis direction and the Y-axis direction (non-scanning direction) is defined as a Y-axis direction. In addition, directions around the X axis, the Y axis, and the Z axis are defined as θX, θY, and θZ directions, respectively. Here, the “substrate” includes a semiconductor wafer coated with a resist, and the “mask” includes a reticle on which a device pattern to be reduced and projected onto the substrate is formed.

The illumination optical system IL illuminates the mask M supported by the mask stage MST with the exposure light EL, and includes an exposure light source, an optical integrator for equalizing the illuminance of a light beam emitted from the exposure light source, and an optical integrator. A condenser lens, a relay lens system, and a variable field stop for setting an illumination area on the mask M by the exposure light EL in a slit shape. A predetermined illumination area on the mask M is illuminated by the illumination optical system IL with exposure light EL having a uniform illuminance distribution. The exposure light EL emitted from the illumination optical system IL includes, for example, ultraviolet bright lines (g-line, h-line, i-line) emitted from a mercury lamp and far ultraviolet light (KrF excimer laser light (wavelength: 248 nm)). DUV light) and, ArF excimer laser light (wavelength 193 nm) and _{F 2} laser beam (wavelength 157 nm) vacuum ultraviolet light (VUV light) and the like. In the present embodiment, ArF excimer laser light is used.

  The mask stage MST supports the mask M, and is two-dimensionally movable in a plane perpendicular to the optical axis AX of the projection optical system PL, that is, in an XY plane, and is capable of minute rotation in the θZ direction. The mask stage MST is driven by a mask stage driving device MSTD such as a linear motor. The mask stage driving device MSTD is controlled by the control device CONT. The position and the rotation angle of the mask M on the mask stage MST in the two-dimensional direction are measured in real time by a laser interferometer, and the measurement result is output to the control device CONT. The control device CONT drives the mask stage driving device MSTD based on the measurement result of the laser interferometer to position the mask M supported by the mask stage MST.

  The projection optical system PL projects and exposes the pattern of the mask M onto the substrate P at a predetermined projection magnification β, and is composed of a plurality of optical elements (lenses). These optical elements are mirrors as metal members. It is supported by the cylinder PK. In the present embodiment, the projection optical system PL is a reduction system in which the projection magnification β is, for example, ４ or ５. Note that the projection optical system PL may be either a unity magnification system or an enlargement system. Further, the projection optical system PL has an imaging characteristic adjusting device PLC for correcting optical characteristics (imaging characteristics). The image forming characteristic adjusting device PLC has, for example, an interval adjusting mechanism for some of the lens groups constituting the projection optical system PL and a gas pressure adjusting mechanism in the lens chamber of some of the lens groups, and performs these adjustments. This corrects optical characteristics such as the projection magnification and distortion of the projection optical system PL. The imaging characteristic adjustment device PLC is controlled by the control device CONT.

  The substrate stage PST supports the substrate P, and includes a Z stage 51 that holds the substrate P via a substrate holder, an XY stage 52 that supports the Z stage 51, and a base 53 that supports the XY stage 52. It has. The substrate stage PST is driven by a substrate stage driving device PSTD such as a linear motor. The substrate stage driving device PSTD is controlled by the control device CONT. By driving the Z stage 51, the position (focus position) of the substrate P held on the Z stage 51 in the Z axis direction and the positions in the θX and θY directions are controlled. In addition, by driving the XY stage 52, the position of the substrate P in the XY directions (the position in a direction substantially parallel to the image plane of the projection optical system PL) is controlled. That is, the Z stage 51 controls the focus position and the tilt angle of the substrate P to adjust the surface of the substrate P to the image plane of the projection optical system PL by the auto-focus method and the auto-leveling method, and the XY stage 52 controls the substrate P Are performed in the X-axis direction and the Y-axis direction. It goes without saying that the Z stage and the XY stage may be provided integrally.

  On the substrate stage PST (Z stage 51), a movable mirror 54 that moves with respect to the projection optical system PL together with the substrate stage PST is provided. A laser interferometer 55 is provided at a position facing the movable mirror 54. The two-dimensional position and the rotation angle of the substrate P on the substrate stage PST are measured in real time by the laser interferometer 55, and the measurement result is output to the control device CONT. The control device CONT drives the substrate stage driving device PSTD based on the measurement result of the laser interferometer 55 to position the substrate P supported by the substrate stage PST.

  In the present embodiment, the immersion method is applied to improve the resolution by substantially shortening the exposure wavelength and substantially widen the depth of focus. Therefore, at least while the image of the pattern of the mask M is being transferred (projected) onto the substrate P, the distance between the surface of the substrate P and the tip surface (lower surface) 7 of the optical element on the substrate P side of the projection optical system PL is changed. Is filled with a predetermined liquid 50. In the present embodiment, pure water is used for the liquid 50. The pure water is used not only for the ArF excimer laser light but also for the exposure light EL as far ultraviolet rays such as ultraviolet bright lines (g line, h line, i line) emitted from a mercury lamp and KrF excimer laser light (wavelength 248 nm). When light (DUV light) is used, the exposure light EL can be transmitted. Further, a parallel flat plate that can transmit the exposure light EL is provided on the tip end surface 7 of the projection optical system PL. This parallel plane plate forms a part of the projection optical system PL.

  The exposure apparatus EX includes a liquid supply device 1 that supplies a predetermined liquid 50 to a space 56 between the distal end surface 7 of the projection optical system PL and the substrate P, and a liquid recovery device 2 that recovers the liquid 50 in the space 56. Have. The liquid supply device 1 includes a tank for accommodating the liquid 50, a pressure pump, a temperature adjusting device for adjusting the liquid 50 supplied to the space 56 to a predetermined temperature, and the like. One end of a supply pipe 3 is connected to the liquid supply device 1, and a supply nozzle 4 is connected to the other end of the supply pipe 3. The liquid supply device 1 supplies the liquid 50 to the space 56 via the supply pipe 3 and the supply nozzle 4. Here, the temperature adjusting device provided in the liquid supply device 1 sets the temperature of the liquid 50 to be supplied to the space 56 to, for example, approximately the same as the temperature in the chamber in which the exposure device EX is housed.

  The liquid recovery device 2 includes a suction pump, a tank for storing the recovered liquid 50, and the like. One end of a recovery pipe 6 is connected to the liquid recovery apparatus 2, and a recovery nozzle 5 is connected to the other end of the recovery pipe 6. The liquid recovery device 2 recovers the liquid 50 in the space 56 via the recovery nozzle 5 and the recovery pipe 6. When the space 56 is filled with the liquid 50, the control device CONT drives the liquid supply device 1 to supply a predetermined amount of the liquid 50 per unit time to the space 56 via the supply pipe 3 and the supply nozzle 4. The recovery device 2 is driven to recover a predetermined amount of the liquid 50 per unit time from the space 56 via the recovery nozzle 5 and the recovery pipe 6. As a result, a predetermined amount of liquid 50 is disposed in space 56 between distal end surface 7 of projection optical system PL and substrate P.

  Next, an autofocus detection device 100 as a surface position detection device that detects the position (focus position) of the surface S of the substrate P in the Z-axis direction will be described.

  The autofocus detection device (AF detection device) 100 includes a light transmission system 8 that projects detection light L (L1, L2) for AF detection onto the surface (test surface) S of the substrate P, and the surface S of the substrate P. A light receiving system 9 that receives the reflected light of the reflected detection light L; As shown in FIG. 1, the light transmission system 8 transmits the two detection lights, the first detection light L1 and the second detection light L2, to the surface of the substrate P from different directions at different angles of incidence. Project on S. Each of the detection light beams L1 and L2 from the light transmission system 8 passes through a part of the projection optical system PL (a part of the optical element) as a light transmitting member and the substrate 50 via the liquid 50 filled in the space 56. Is projected on the surface S of the Here, the detection light L1, L2 is projected onto the surface S of the substrate P via a part of the projection optical system PL for the following reason. That is, in order to stably arrange the liquid 50 in the space 56, the distance d needs to be set to a predetermined amount (for example, about 2 to 3 mm) so that the surface tension of the liquid 50 can be maintained. However, at such a distance d, it is difficult to directly project the detection lights L1 and L2 from the light transmitting system 8 onto the surface S of the substrate P by the oblique incidence method. The liquid 50 is not stably arranged in the space 56. In the present invention, since the detection lights L1 and L2 are projected on the surface S of the substrate P via a part of the projection optical system PL, a desired distance d for stably disposing the liquid 50 in the space 56 is set. , The detection lights L1 and L2 can be projected onto the surface S of the substrate P. As a result, the degree of freedom in setting the distance d (working distance) between the front end surface 7 of the projection optical system PL and the surface S of the substrate P can be increased. Further, the incident angles of the detection lights L1 and L2 with respect to the surface S of the substrate P can be freely changed without being restricted by the position of the projection optical system PL.

  The AF detection device 100 is configured to detect a substrate with respect to an image plane (imaging plane) formed via the projection optical system PL and the liquid 50 based on a detection signal of the light receiving system 9 obtained from light reflected on the surface S of the substrate P. The height position (focus position) of the P surface in the Z-axis direction is obtained. Further, the AF detection device 100 can also obtain the attitude of the substrate P in the tilt direction by obtaining each focus position at each of a plurality of points on the surface of the substrate P. The detection result of the AF detection device 100 is output to the control device CONT, and the control device CONT adjusts the positional relationship between the imaging plane of the projection optical system PL and the surface of the substrate P based on the detection result of the AF detection device 100, A focusing operation for adjusting the surface of the substrate P to within the depth of focus of the projection optical system PL is performed.

FIG. 2 is a configuration diagram illustrating a first embodiment of the AF detection device 100. In FIG. 2, some components other than the AF detection device 100 are not shown. 2, the optical system 8 feeding of AF detecting apparatus 100 includes a first light sending system 8A to project the first detection light L1 in the first incidence angle theta ₁ with respect to the surface S of the substrate P, the substrate P and a second transmitting system 8B projecting the second detection light L2 in a different second incidence angle theta ₂ to the first incident angle theta ₁ with respect to the surface of the. Further, the light receiving system 9A of the AF detection device 100 is provided corresponding to the first light transmitting system 8A, and receives the reflected light of the first detection light L1 reflected by the surface S of the substrate P. And a second light receiving system 9B provided corresponding to the second light transmitting system 8B and receiving the reflected light of the second detection light L2 reflected by the surface S of the substrate P.

The first light transmission system 8A forms an AF light source 10 that emits a non-photosensitive light beam (wavelength of about 400 nm to 900 nm) to the photoresist on the substrate P, and shapes the light beam emitted from the light source 10 into slit light. A light transmitting slit 11 having a slit-like opening, a cylindrical lens 12 for correcting astigmatism, a relay lens 13, an optical path bending mirror 14, a plane plate 15 for correcting aberration, and an objective lens 16 are provided. . The slit light shaped by the light transmission slit 11 is used as a first detection light L1 via a cylindrical lens 12, a relay lens 13, an optical path bending mirror 14, an aberration correction plane plate 15, and an objective lens 16 to form a projection optical system PL. Incident on. Note that the barrel PK has an opening, and the slit light enters the projection optical system PL through this opening. First detection light L1 incident on the projection optical system PL is projected at a first angle of incidence theta ₁ to the surface S of the substrate P through the liquid 50.

  The reflected light L1r of the first detection light L1 reflected on the surface S of the substrate P is received by the first light receiving system 9A via the liquid 50 and a part of the projection optical system PL. Here, the lens barrel PK has an opening, and the reflected light L1r is received by the first light receiving system 9A via this opening. The first light receiving system 9A includes an objective lens 17, on which reflected light L1r via the projection optical system PL is incident, a plane plate for aberration correction 18, a vibration mirror 19 vibrating at a predetermined cycle, a relay lens 20, The apparatus includes a cylindrical lens 21 for correcting astigmatism, a light receiving slit 22 having a slit-shaped opening, and a light receiving sensor 23 made of, for example, a silicon photodiode. The reflected light L1r of the first detection light L1 on the surface S of the substrate P is received via the objective lens 17, the aberration correction plane plate 18, the vibration mirror 19, the relay lens 20, the cylindrical lens 21, and the light receiving slit 22. The light is received by the sensor 23. The vibrating mirror 19 vibrates in the θY direction at a predetermined cycle as indicated by an arrow y. With the vibration of the vibration mirror 19, the image of the slit pattern formed in the light receiving slit 22 (the slit-shaped reflected light L1r shaped by the light transmitting slit 11 and reflected by the surface S of the substrate P) also vibrates. With the vibration of the image of the slit pattern, the amount of light passing through the opening of the light receiving slit 22 changes. The light that has passed through the opening of the light receiving slit 22 reaches the light receiving sensor 23. Here, the position of the opening of the light-receiving slit 22 is such that the center of the opening of the light-receiving slit 22 is located when the surface S of the substrate P, which is the surface to be measured, and the imaging plane of the projection optical system PL coincide with each other. The slit pattern is provided so as to coincide with the vibration center of the image. Therefore, if the image of the slit pattern received by the light receiving sensor 23 is detected at a constant period, the image forming plane of the projection optical system PL and the surface S of the substrate P match. On the other hand, when the imaging plane of the projection optical system PL does not match the surface S of the substrate P, the reflected light L1r based on the first detection light L1 is perpendicular to the optical axis of the first light receiving system 9A. Since the center of vibration of the image of the slit pattern is shifted with respect to the center of the opening of the light receiving slit 22, the image of the slit pattern received by the light receiving sensor 23 is not detected at a constant period. The detection result of the light receiving sensor 23 is output to the control device CONT, and the control device CONT obtains the focus position on the surface S of the substrate P based on the light receiving result of the light receiving sensor 23.

The second light transmission system 8B is provided in addition to the first light transmission system 8A based on a focus position adjustment method or a temperature measurement method (refractive index change measurement method) according to the present invention, which will be described later. except that sets the incident angle to the surface of the substrate P of the detection light L2 in the theta _2, because it has the same structure as the first light sending system 8A, a description thereof will be omitted. Similarly, the second light receiving system 9B that receives the reflected light L2r of the second detection light L2 on the surface of the substrate P has the same configuration as that of the first light receiving system 9A, and a description thereof will be omitted. Here, each of the detection lights L1 and L2 projected by each of the first light transmission system 8A and the second light transmission system 8B has the same wavelength. When the distance between the front end surface 7 of the projection optical system PL and the surface S of the substrate P can be ensured, the detection light of the AF detection device 100 is transmitted to the surface of the substrate P without passing through a part of the projection optical system PL. May be projected.

  Next, a method for detecting surface position information of the surface S of the substrate P using the above-described AF detection device 100 will be described.

FIG. 3 is an enlarged view near the surface S of the substrate P on which the first and second detection lights L1 and L2 are projected. The control device CONT simultaneously projects the first and second detection lights L1 and L2 from the first and second light transmission systems 8A and 8B onto the surface S of the substrate P. The first detection light L1 projected on the surface S of the substrate P at the incident angle theta ₁ through the liquid 50, the second detection light L2 projected onto the surface S of the substrate P at the incident angle theta ₂ through the liquid 50 Is done. The reflected lights L1r, L2r on the surface S of the substrate P based on the first and second detection lights L1, L2 are received by the first and second light receiving systems 9A, 9B, respectively. At this time, the liquid 50 is set to a predetermined temperature T _1, the refractive index of the liquid 50 at this time is n. At this time, the first and second detection lights L1 and L2 are projected on the same position on the surface S of the substrate P. Therefore, in a state where the liquid 50 has no refractive index change (temperature change), when the substrate P moves in the Z-axis direction, the amount of deviation of the reflected light L1r in the direction perpendicular to the optical axis of the light receiving system and the reception of the reflected light L2r. The shift amount in the direction perpendicular to the optical axis of the system is the same.

The substrate P does not move in the Z axis direction, the temperature of the liquid 50 is changed from T ₁ to T _2, consider the case where the refractive index n of the liquid 50 is changed by [Delta] n. Due to the temperature change, the first and second detection lights L1 and L2 from the first and second light transmission systems 8A and 8B change the refraction angle at the interface from the projection optical system PL to the liquid 50. With the change of the refraction angle, the optical paths of the first and second detection lights L1 and L2 change as indicated by reference numerals L1 'and L2', whereby the surface S of the substrate P of the first detection light L1 is changed. the incident angle is _'changed to angle of incidence with respect to the surface S of the substrate P in the second detection light L2 theta ₂ from theta _2' theta ₁ from theta ₁ changes for. Then, the optical path of the reflected light L1r of the first detection light L1 is shifted by a distance D1 in a direction perpendicular to the optical axis of the light receiving system 9A to become the reflected light L1r ′. Similarly, the optical path of the reflected light L2r of the second detection light L2 is shifted by a distance D2 in a direction perpendicular to the optical axis of the light receiving system 9B to become the reflected light L2r '.

Here, it is assumed that the thickness of the liquid is d, and the refractive index of the liquid 50 changes from n by Δn with temperature. In this case, the angle of incidence of the detection light on the substrate surface changes, and the change amount Δθ is
Δθ = arcsin [n / (n + Δn)] · sinθ (3)
It is. Assuming that the surface S of the substrate P does not move in the Z-axis direction, the detection error amount Δd of the focus position on the surface of the substrate P becomes
Δd = d · [tan (θ + Δθ) -tanθ] / (2tanθ) (4)
It becomes. That is, the detection error amount Δd is determined by the focus position on the surface of the substrate P detected based on the detection light L before the change in the refractive index of the liquid and the focus position on the surface of the substrate P detected based on the detection light L ′ after the change in the refractive index of the liquid. It is an error with the position.

Here, as can be seen from equation (3), Δθ depends on the value of θ. Since θ ₁ ≠ θ ₂ , the change amount Δθ ₁ of the incident angle of the first detection light L1 (= θ ₁ ′ −θ ₁ ) and the change amount Δθ ₂ of the incident angle of the second detection light L2 (= θ ₂ ′ −θ ₂ ). Therefore, a detection error amount [Delta] d ₁ of the focus position based on the first detection light L1, the detection error amount [Delta] d ₂ of the focus position based on the second detection light L2 show different values.

  FIG. 4 shows an example of the relationship between the incident angle θ of the detection light L with respect to the surface S of the substrate P and the detection error amount Δd of the focus position on the surface of the substrate P caused by a change in the temperature of the liquid. FIG. 4 shows the detection light when the temperature changes by 0.01 ° C. when the liquid 50 is pure water (water) and the thickness d of the water corresponding to the working distance of the projection optical system PL is 1 mm. The relationship between the incident angle θ of L and the focus detection error amount Δd is shown.

For example, the incident angle theta ₁ is 80 degrees of the first detection light L1, when the incident angle theta ₂ of the second detection light L2 is set to 85 degrees, the temperature of the pure water as the liquid 50 from T ₁ When the temperature changes by 0.01 ° C. to reach T ₂ , the detection error amount Δd ₁ of the focus position based on the first detection light L ₁ is about 20 nm from FIG. 4, and the focus position based on the second detection light L 2 the detection error amount [Delta] d ₂ of about 80 nm. That is, according to the example of FIG. 4, when the temperature of the liquid (water) 50 having a thickness of 1 mm changes by 0.01 ° C., the detection error amounts Δd ₁ and Δd _{2 of the} focus position based on the two detection lights L1 and L2. Has a difference of 60 nm.

As is apparent from the above equations (3) and (4), the detection error amount Δd of the focus position based on the detection light is substantially proportional to the change in the refractive index due to the temperature change of the liquid. Therefore, the difference (Δd ₁ −Δd ₂ ) between the detection error amount Δd ₁ of the focus position based on the first detection light L ₁ and the detection error amount Δd ₂ of the focus position based on the second detection light L ₂ is also the temperature of the liquid. It is almost proportional to the refractive index change due to the change. For example, in the relationship of FIG. 4, if the refractive index of the liquid changes by Δn due to a change in the liquid temperature of 0.01 ° C., the difference (Δd ₁ −Δd ₂ ) in the detection error amount at a certain temperature change is 30 nm (= 60 nm). / 2), the change in the refractive index of the liquid caused by the temperature change is Δn / 2.

That is, the focus position _{Z 1} of the surface of the substrate P detected by the first detection light L1, the difference between the focus position _{Z 2} of the surface of the substrate P detected by the second detection light L2 _(Z 1 _-Z 2) Does not change unless there is a temperature change (refractive index change) of the liquid because the same position on the surface of the substrate P is detected. However, when the refractive index changes due to the temperature change of the liquid, the detection difference of the focus position ( Z ₁ −Z ₂ ) changes in proportion to the change in the refractive index. Conversely, it is possible to detect the change in refractive index of the liquid from the detected difference (Z 1 _{-Z 2)} of the focus position. In the present embodiment, the control device CONT stores the relationship between the detection difference (Z ₁ -Z ₂ ) of the focus position and the amount of change in the refractive index, which is obtained in advance by experiment or simulation, and stores the AF detection device 100. Can be used to determine the amount of change in the refractive index based on the focus positions Z ₁ and Z ₂ detected.

Since the temperature change and refractive index change of the liquid is proportional to the detected difference between the focus position (Z 1 _{-Z 2)} is varied in proportion to the temperature change of the liquid. Therefore, the relationship between the detection difference (Z ₁ −Z ₂ ) of the focus position and the amount of change in the refractive index, or the relationship between the amount of change in the temperature of the liquid and the amount of change in the refractive index of the liquid is also stored in the control device CONT. In other words, the amount of change in the liquid temperature can be determined based on the focus positions Z ₁ and Z ₂ detected using the AF detection device 100.

Next, the procedure for detecting the surface of the substrate P will be described with reference to the flowchart of FIG. Incidentally, AF detecting apparatus 100 in the initial state, the focus position Z ₁ which is detected based on the detection light L1, the focus position Z ₂ which is detected based on the detection light L2 is adjusted to be the same I have. The focus positions Z ₁ and Z ₂ are each detected as a deviation from the image plane. For simplicity, FIG. 5 describes a case where the position of the surface of the substrate P in the Z-axis direction does not change.

The AF detection device 100 projects the first detection light L1 and the second detection light L2 toward the surface of the substrate P based on a command from the control device CONT, and also detects the surface of the substrate P corresponding to the detection lights L1 and L2. reflected light L1r from, respectively received by the light receiving sensor 23 L2r, the focus position _{Z 1} of the surface of the substrate P based on the first detection light L1, the focus position _{Z 2} of the surface of the substrate P based on the second detection light L2 Are respectively detected (step S1).

The control device CONT obtains the difference (Z ₁ -Z ₂ ) between the detected focus positions Z ₁ and Z _2, and detects the focus position detection difference (Z ₁ -Z ₂ ) stored in advance and the refraction of the liquid 50. The refractive index change amount Δn of the liquid 50 is obtained based on the relationship information with the index change amount Δn (step S2).

Further, the control unit CONT based on the refractive index variation Δn obtained in step S2, corrects the focus position Z ₁ of the first detection light L1 obtained in step S1. Specifically, the equation stored in advance (3), (4) using obtains the incidence angle variation [Delta] [theta] ₁ caused by a refractive index change amount Δn obtained in step S2, on the basis of the [Delta] [theta] ₁ by the first detection light L1 obtains detection error amount [Delta] d ₁ of the focus position. Then, based on the detected error amount [Delta] d _1, the first detection light L1 to correct the focus position Z ₁ of the detected surface of the substrate P by using the actual focus position of the substrate P surface (surface position information) It is determined (step S3).

  Then, the control device CONT drives the substrate stage PST based on the corrected surface position information on the surface of the substrate P so that the surface of the substrate P obtained by the correction matches the image surface, and the image plane and the substrate The positional relationship between P and the surface S is adjusted (step S4).

Here, the case where the thickness d of the liquid 50 is 1 mm has been described, but the relationship corresponding to a plurality of thicknesses d is stored in the control device CONT in advance. Further, here, the liquid 50 is pure water, but the above-described relationship according to the liquid to be used is stored in advance. Also, rather than the focus position Z ₁ is detected with the first detection light L1, the focus position Z ₂ may be used to correct detected using a second detection light L2. However, since the detection sensitivity and the detection resolution are higher when the incident angle is larger, it is desirable to use the second detection light L2 as the main detection light and use the first detection light L1 as the correction detection light.

Meanwhile, in order to determine accurately the refractive index information, it is preferable as large as possible the difference between the incident angle theta ₁ and the incident angle theta _2. On the other hand, when the incident angle with respect to the surface S of the substrate P decreases, the position detection accuracy of the substrate P in the Z-axis direction decreases. Therefore, it is preferable that the incident angles of the detection lights L1 and L2 with respect to the surface of the substrate P satisfy the condition of 30 ° ≦ θ <90 °. More preferably, the incident angles of the detection lights L1 and L2 with respect to the surface of the substrate P satisfy the condition of 70 ° ≦ θ <90 ° so that reflected light having a sufficient light amount can be obtained on the surface S of the substrate P. Is preferred. That is, as shown in the graph of FIG. 4, if the incident angle is 70 ° or more, the error amount greatly changes with respect to the change of the incident angle, and thus the temperature change (refraction index change) of the liquid 50 is sensitive. Can be detected.
Further, when detecting the surface position of the surface of the substrate P via the liquid (water) as in the present embodiment, the refractive index of the liquid (water) with respect to the detection lights L1 and L2 and the photosensitive material on the surface of the substrate P The difference from the refractive index of (resist) becomes small, and the irradiated detection light does not sufficiently reflect on the surface of the photosensitive material, and the amount of light (light intensity) received by the light receiving sensor may be reduced. Instead, a part of the irradiated detection light may pass through the photosensitive material and reach the ground under the photosensitive material, and the light reflected from the underlying surface may be received by the light receiving sensor as a noise component. Therefore, the difference between the refractive index of the liquid (water) and the refractive index of the photosensitive material (resist) on the surface of the substrate P with respect to the detection lights L1 and L2, the reflectance on the photosensitive material surface, and the noise light from the ground below the photosensitive material Considering the influence and the like, it is desirable that the incident angles of the detection lights L1 and L2 are respectively 84 ° <θ <90 °.

  When the image plane matches the surface S of the substrate P in this way, the control device CONT illuminates the mask M with the exposure light EL, and transfers the pattern of the mask M to the substrate P via the projection optical system PL.

  If the refractive index of the liquid 50 fluctuates due to a change in temperature during the exposure process, when the pattern of the mask M is transferred to the substrate P via the projection optical system PL and the liquid 50, the image of the pattern transferred to the substrate P An error may occur. For example, with the change in the refractive index of the liquid 50, various aberrations such as scaling of the pattern image transferred to the substrate P may change or the image plane position may change compared to before the change in the refractive index. The control device CONT is configured to perform an operation based on the refractive index change amount (or temperature change amount) of the liquid 50 obtained by using the AF detection device 100 so that no error occurs in the pattern image transferred to the substrate P. The image of the pattern image is adjusted using the image characteristic adjustment device PLC. For example, when the image plane position of the projection optical system PL shifts in the Z-axis direction due to a change in the refractive index of the liquid 50, some optical elements in the projection optical system PL are driven or the mask is moved. By adjusting the wavelength of the exposure light EL, the image plane of the pattern via the projection optical system PL and the liquid 50 matches the surface S of the substrate P. Alternatively, even when various aberrations such as scaling and distortion of a pattern image change due to a change in the refractive index (temperature change) of the liquid 50, the mask M is similarly moved in the Z-axis direction or the tilt direction. By driving some optical elements in the projection optical system PL or adjusting the wavelength of the exposure light EL, an error in the pattern image due to a change in the refractive index (temperature change) of the liquid 50 is prevented. Perform image adjustment.

As described above, even if the refractive index on the optical path of the detection light changes, by projecting the two detection lights L1 and L2 onto the surface S of the substrate P at different incident angles θ ₁ and θ ₂ , The refractive index information of the liquid existing on the optical path of the detection light can be obtained by using the measurement error of the surface position information based on the detection lights L1 and L2. Therefore, the detected surface position information can be corrected based on the obtained refractive index information, so that the surface position information of the surface S of the substrate P can be accurately detected.
In the above-described embodiment, since the incident angle theta ₁ of the two detection light L1, _L2, theta ₂ is greater than 80 °, in order to simplify the explanation, the refractive index change in the liquid 50 (temperature change ), When the substrate P moves in the Z-axis direction, the shift amount of the reflected light L1r in the direction perpendicular to the optical axis of the light receiving system and the shift amount of the reflected light L2r in the direction perpendicular to the optical axis of the light receiving system are calculated. Has been described as the same, but strictly speaking, since the incident angles θ ₁ and θ _{2 of the} two detection lights L 1 and L ₂ are different, the liquid 50 has no change in the refractive index (temperature change). When P moves in the Z-axis direction, the amount of deviation of the reflected light L1r in a direction perpendicular to the optical axis of the light receiving system differs from the amount of deviation of the reflected light L2r in the direction perpendicular to the optical axis of the light receiving system. In such a case, the displacement of the reflected light L1r in the direction perpendicular to the optical axis of the light receiving system and the displacement of the reflected light L2r in the direction perpendicular to the optical axis of the light receiving system due to the displacement of the substrate P in the Z direction. If the relationship with the amount is determined in advance, and if the measurement result based on the actual two reflected lights is different from the relationship determined in advance, it is determined that a temperature change (refractive index change) of the liquid 50 has occurred. Good.

  As described above, pure water is used as the liquid 50 in the present embodiment. Pure water has the advantage that it can be easily obtained in large quantities at a semiconductor manufacturing plant or the like, and that there is no adverse effect on the photoresist on the substrate P, optical elements (lenses), and the like. In addition, since pure water has no adverse effect on the environment and has a very low impurity content, an effect of cleaning the surface of the substrate P and the surface of the optical element provided on the tip end surface of the projection optical system PL can be expected. .

  Since the refractive index n of pure water (water) with respect to the exposure light EL having a wavelength of about 193 nm is said to be about 1.44 to 1.47, an ArF excimer laser light (wavelength When 193 nm is used, the wavelength is shortened to 1 / n, that is, about 131 to 134 nm on the substrate P, and high resolution is obtained. Further, since the depth of focus is expanded to about n times, that is, about 1.44 to 1.47 times as compared with that in the air, if it is sufficient to secure the same depth of focus as when using in air, The numerical aperture of the projection optical system PL can be further increased, and the resolution is also improved in this regard.

  In the present embodiment, as described above, the plane-parallel plate capable of transmitting the exposure light EL is provided on the distal end surface 7 of the projection optical system PL. This plane-parallel plate is detachably (exchangeably) attached to the distal end surface of the projection optical system PL. By making the optical element that comes into contact with the liquid 50 a parallel plane plate that is less expensive than a lens, the transmittance of the projection optical system PL and the exposure light EL on the substrate P during transportation, assembly, adjustment, and the like of the exposure apparatus EX. Even if a substance (for example, a silicon-based organic substance) that reduces the illuminance and the uniformity of the illuminance distribution adheres to the parallel flat plate, it is sufficient to replace the parallel flat plate just before supplying the liquid 50. There is an advantage that the replacement cost is reduced as compared with the case where the optical element that comes into contact with the lens is a lens. That is, the surface of the optical element that comes into contact with the liquid 50 due to scattering particles generated from the resist due to the irradiation of the exposure light EL or the adhesion of impurities in the liquid 50 is stained. Although it is necessary to use this optical element as an inexpensive parallel flat plate, the cost of replacement parts can be reduced and the time required for replacement can be reduced as compared with a lens, and the maintenance cost (running cost) increases. And a decrease in throughput can be suppressed. Of course, the optical element attached to the distal end surface of the projection optical system PL may be a lens. Further, the optical element attached to the distal end surface of the projection optical system PL may be an optical plate used for adjusting optical characteristics of the projection optical system PL, for example, aberrations (spherical aberration, coma aberration, etc.). In addition, at the tip of the projection optical system PL, only the optical element (parallel flat plate or lens) is brought into contact with the liquid 50 and the lens barrel PK is not contacted, so that the metal lens barrel PK is not corroded. Is prevented.

  When the pressure between the optical element at the tip of the projection optical system PL and the substrate P caused by the flow of the liquid 50 is large, the optical element is not replaced but the optical element is moved by the pressure. It may be fixed firmly so that it does not occur.

In this embodiment, an example in which the two detection lights L1 and L2 are projected on the surface S of the substrate P at different incident angles θ ₁ and θ ₂ has been described. Can project not only two light beams but also three or more light beams. When allowing the detection light L1 and L2 to pass through a part of the projection optical system, only one of the plurality of optical elements constituting the projection optical system PL that is closest to the substrate P may pass. Alternatively, the light may pass through a plurality of optical elements.

  In the present embodiment, the space between the front end surface 7 of the projection optical system PL and the surface S of the substrate P is filled with the liquid 50. For example, a cover made of a flat plate parallel to the surface S of the substrate P is used. The liquid 50 may be filled with glass attached. In this case, the detection lights L1 and L2 from the light transmission system 8 are projected on the surface S of the substrate P via a cover glass as a light transmitting member in addition to a part of the projection optical system PL and the liquid 50. become.

In the present embodiment, the case where the space 50 between the front end surface 7 of the projection optical system PL and the surface S of the substrate P is filled with the liquid 50 has been described as an example. For example, the present invention can of course be applied to a case where the space 56 is filled with a gas such as air. In this case, the refractive index information of the gas in the space 56 can be detected based on the detection light projected on the surface S of the substrate P at a plurality of different incident angles. Then, it is possible to detect a temperature change of the gas in the space 56 based on the detection light. In addition, substances other than the liquid (water) 50 and air may exist on the optical path of the detection light including the space 56. For example, a liquid other than water, such as an optical element (glass or lens) that can transmit light or a liquid such as a fluorine-based (fluorine-based liquid) or perfluoropolyether (PFPE) oil, may be present. In particular, when using a vacuum ultraviolet light of F ₂ laser light or the like as the exposure light, it is preferable to use the vacuum ultraviolet light capable of transmitting fluorinated oil as the liquid. Also in this case, based on the detection light projected on the surface S of the substrate P, it is possible to detect the refractive index information including the temperature change of, for example, an optical element or a fluorine-based oil existing on the optical path. According to the principle of the present invention, a change in temperature of a substance can be obtained through a change in refractive index. Therefore, the present invention can be used for a method of measuring temperature change of a fluid such as a gas or a liquid having optical transparency and a solid. it can. In particular, the method of the present invention is effective in a small area where temperature measurement is difficult with a normal temperature sensor, a high temperature atmosphere, a high pressure atmosphere, a highly corrosive atmosphere, and the like.

  In the present embodiment, the detection light beams L1 and L2 pass through the projection optical system PL, but the refractive index of the projection optical system PL also slightly changes with a change in temperature. Also in this case, the temperature change (refractive index change) of the projection optical system PL can be obtained by obtaining the error amount based on each of the plurality of detection light beams having different incident angles.

  Next, a second embodiment of the AF detection device 100 will be described with reference to FIG. Here, in the following description, the same or equivalent components as those of the first embodiment described with reference to FIG. 2 are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

  In the AF detection device 100 shown in FIG. 6, one light transmission system 8 and one light reception system 9 are provided. A feature of the present embodiment is that the light transmission system 8 is provided with a wavelength selection filter 24. The light transmission system 8 includes a light source 10, a wavelength selection filter 24 provided downstream of an optical path of a light beam emitted from the light source 10, a light transmission slit 11, a cylindrical lens 12 for correcting astigmatism, and a relay lens 13. , An optical path bending mirror 14, an aberration correcting plane plate 15, and an objective lens 16. The light receiving system 9 includes an objective lens 17 on which reflected light from the projection optical system PL is incident, a plane plate for aberration correction 18, a vibration mirror 19 that vibrates at a predetermined cycle, a relay lens 20, an astigmatism, It comprises a correcting cylindrical lens 21, a dichroic mirror 26, light receiving slits 22a and 22b having slit-shaped openings, and light receiving sensors 23a and 23b made of, for example, silicon photodiodes.

  The wavelength selection filter 24 can set the wavelength of the detection light projected on the liquid 50 and the substrate P. That is, the light transmission system 8 can project a plurality of detection lights having different wavelengths onto the surface S of the substrate P by the wavelength selection filter 24. For example, when the first detection light L1 having the first wavelength and the second detection light L2 having the second wavelength different from the first wavelength are incident on the liquid 50 from the projection optical system PL. Different refraction angles. Therefore, the incident angles when the first and second detection lights L1 and L2 having different wavelengths pass through the respective liquids 50 and are projected on the substrate P are different from each other.

  For example, consider a case where the liquid 50 is water, and a C line (wavelength 656.3 nm) is projected as the first detection light L1 and a d line (wavelength 587.6 nm) is projected as the second detection light L2. When the incident angle of the d-line with respect to the surface S of the substrate P is 80 degrees, the difference between the d-line and the C-line with respect to the surface S of the substrate P is 0.14 degrees.

  The reflected lights L1r and L2r reflected on the surface of the substrate P enter the light receiving system 9, respectively. Then, the reflected light L1r transmitted through the dichroic mirror 26 in the light receiving system 9 enters the light receiving sensor 23a, and the reflected light L2r reflected by the dichroic mirror 26 enters the light receiving sensor 23b. The detection results of the light receiving sensors 23a and 23b are output to the control unit CONT, and the refractive index information of the liquid 50 can be obtained as in the first embodiment. When there is no dichroic mirror 26 in the light receiving system 9 and only one light receiving sensor 23 is disposed, the wavelength selection filter 24 detects the first wavelength detection light L1 and the second wavelength detection light L2. May be alternately incident on the surface of the substrate P.

  Next, a third embodiment of the AF detection device 100 will be described with reference to FIG. In the AF detection device 100 shown in FIG. 7, one light transmitting system 8 and one light receiving system 9 are provided. The feature of the present embodiment is that the pupil division plate 25 is provided in the light transmission system 8. The light transmission system 8 includes a light source 10, a light transmission slit 11, a cylindrical lens 12 for astigmatism correction, a relay lens 13, an optical path bending mirror 14, a plane plate 15 for aberration correction, an objective lens 16, A pupil splitting plate 25 provided in the vicinity of the objective lens 16 on the downstream side of the optical path. The light receiving system 9 includes an objective lens 17 on which reflected light from the projection optical system PL is incident, a plane plate for aberration correction 18, a vibration mirror 19 that vibrates at a predetermined cycle, a relay lens 20, an astigmatism, A correction cylindrical lens 21, a light receiving slit 22 having a slit-shaped opening, and a light receiving sensor 23 made of, for example, a silicon photodiode are provided.

The pupil splitting plate 25 has a predetermined opening 25A, and allows a part of the light beam applied to the pupil splitting plate 25 to pass through the opening 25A. That is, as shown in FIGS. 8A and 8B, the pupil splitting plate 25 is moved in the direction perpendicular to the optical axis of the light transmitting system to split the light beam into pupils, thereby obtaining the surface S of the substrate P. Are set to different incident angles θ ₁ and θ ₂ from each other, and the reflected light L1r and L2r corresponding thereto are detected by the light receiving sensor 23, so that the liquid 50 as in the first embodiment. Refractive index information can be determined. Also, by alternately repeating the states of FIG. 8A and FIG. 8B, the refractive index information of the liquid 50 can be obtained almost in real time. Also in the third embodiment, by disposing the pupil splitting plate 25, as in the second embodiment, even in the case of one light transmission system 8 and one light reception system 9, a plurality of detection lights can be transmitted to the substrate P at different incident angles. Can be projected. Note that a pupil splitting plate may be provided between the substrate P of the light receiving system 9 and the objective lens 17 to prevent disturbance such as stray light.

  In the above-described embodiment, the optimal image plane of the pattern image and the surface S of the substrate P are determined based on the temperature information (refractive index information) of the liquid 50 optically detected by the AF detection device 100. And the adjustment of the pattern image projected on the substrate P, the temperature of the liquid supplied from the liquid supply device 1 is controlled based on the detected temperature information. You may do so. This makes it possible to optimize the temperature (refractive index) of the liquid 50 between the projection optical system PL and the substrate P.

  In the above-described embodiment, the detection light is projected on the surface of the substrate P as the surface to be detected. However, the detection light is not limited to the surface of the substrate P. For example, a reference plane or a reference plane formed on the substrate stage PST may be used. The detection light may be projected using the upper surface of the sensor as the surface to be detected.

  In the above embodiment, the detection light is projected near the center of the projection area where the image of the pattern of the mask M is projected. However, the detection light may be projected outside the projection area. Good.

  Further, in the above-described embodiment, the AF detection device 100 projects two detection lights on the surface to be detected, but it is needless to say that the number is not limited to two and may be three or more. In this case, since a plurality of pieces of refractive index change information (temperature change information) can be obtained, it is possible to obtain more accurate refractive index change information (temperature change information) by calculating an average value and the like. It becomes.

  The substrate P of the above embodiment is not limited to a semiconductor wafer for manufacturing a semiconductor device, but also a glass substrate for a display device, a ceramic wafer for a thin-film magnetic head, or an original mask or reticle used in an exposure apparatus. (Synthetic quartz, silicon wafer) and the like are applied.

  As an exposure apparatus EX, a mask M and a substrate P are used in addition to a step-and-scan type scanning exposure apparatus (scanning stepper) that scans and exposes the pattern of the mask M by synchronously moving the mask M and the substrate P. The present invention can also be applied to a step-and-repeat type projection exposure apparatus (stepper) in which the pattern of the mask M is exposed collectively in a stationary state and the substrate P is sequentially moved stepwise. The present invention is also applicable to a step-and-stitch type exposure apparatus that transfers at least two patterns on the substrate P while partially overlapping each other.

  The present invention is also applicable to a twin-stage type exposure apparatus. The structure and exposure operation of a twin-stage type exposure apparatus are described in, for example, JP-A-10-163099 and JP-A-10-214783 (corresponding to U.S. Pat. Nos. 6,341,007, 6,400,441, 6,549,269). And 6,590,634), JP-T-2000-505958 (corresponding U.S. Pat. No. 5,969,441) or U.S. Pat. No. 6,208,407.

  Further, in the above-described embodiment, the exposure apparatus that locally fills the liquid between the projection optical system PL and the substrate P is used, but the stage holding the substrate to be exposed is moved in the liquid tank. The present invention is also applicable to an immersion exposure apparatus or an immersion exposure apparatus in which a liquid tank having a predetermined depth is formed on a stage and a substrate is held therein. Regarding the structure and exposure operation of an immersion exposure apparatus that moves a stage holding a substrate to be exposed in a liquid tank, for example, Japanese Patent Application Laid-Open No. 6-124873 discloses a liquid tank having a predetermined depth formed on a stage. A liquid immersion exposure apparatus for holding a substrate therein is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-303114 and US Pat. No. 5,825,043.

  The type of the exposure apparatus EX is not limited to an exposure apparatus for manufacturing a semiconductor element for exposing a semiconductor element pattern onto the substrate P, but may be an exposure apparatus for manufacturing a liquid crystal display element or a display, a thin film magnetic head, an imaging element (CCD). ) Or an exposure apparatus for manufacturing a reticle or a mask.

  When a linear motor is used for the substrate stage PST or the mask stage MST, any of an air levitation type using an air bearing and a magnetic levitation type using Lorentz force or reactance force may be used. Each of the stages PST and MST may be of a type that moves along a guide, or may be a guideless type that does not have a guide. Examples using a linear motor for the stage are disclosed in U.S. Patents 5,623,853 and 5,528,118.

  As a driving mechanism of each stage PST, MST, a planar motor that drives each stage PST, MST by electromagnetic force by facing a magnet unit having a two-dimensionally arranged magnet and an armature unit having a two-dimensionally arranged coil. May be used. In this case, one of the magnet unit and the armature unit may be connected to the stages PST and MST, and the other of the magnet unit and the armature unit may be provided on the moving surface side of the stages PST and MST.

  The reaction force generated by the movement of the substrate stage PST may be mechanically released to the floor (ground) using a frame member so as not to be transmitted to the projection optical system PL. The method of processing this reaction force is disclosed in detail, for example, in Japanese Patent Application Laid-Open No. 8-166475 (US Pat. No. 5,528,118).

  The reaction force generated by the movement of the mask stage MST may be mechanically released to the floor (ground) using a frame member so as not to be transmitted to the projection optical system PL. The method of processing this reaction force is disclosed in detail, for example, in Japanese Patent Application Laid-Open No. 8-330224 (U.S. Pat. No. 5,874,820).

  As described above, the exposure apparatus EX according to the embodiment of the present invention controls various subsystems including the respective components described in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. Manufactured by assembling. Before and after this assembly, adjustments to achieve optical accuracy for various optical systems, adjustments to achieve mechanical accuracy for various mechanical systems, and various electric systems to ensure these various accuracy Are adjusted to achieve electrical accuracy. The process of assembling the exposure apparatus from the various subsystems includes mechanical connection, wiring connection of an electric circuit, and piping connection of a pneumatic circuit among the various subsystems. It goes without saying that there is an assembling process for each subsystem before the assembling process from these various subsystems to the exposure apparatus. When the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed, and various precisions of the entire exposure apparatus are secured. It is desirable that the exposure apparatus be manufactured in a clean room in which the temperature, the degree of cleanliness, and the like are controlled.

  As shown in FIG. 9, for a micro device such as a semiconductor device, a step 201 for designing the function and performance of the micro device, a step 202 for manufacturing a mask (reticle) based on this design step, a substrate as a base material of the device are provided. 203, an exposure processing step 204 of exposing a mask pattern to a substrate by the exposure apparatus EX of the above-described embodiment, a device assembling step (including a dicing step, a bonding step, and a packaging step) 205, an inspection step 206, and the like. Manufactured through

FIG. 1 is a schematic configuration diagram illustrating an embodiment of an exposure apparatus including a surface position detection device according to the present invention. It is a schematic structure figure showing a 1st embodiment of a surface position detecting device of the present invention. It is a principal part enlarged view which shows the board | substrate to which a detection light is projected. FIG. 4 is a diagram illustrating a relationship between an incident angle of detection light with respect to a substrate and an error amount. It is a flowchart figure which shows an example of the surface position detection method of this invention. It is a schematic structure figure showing a 2nd embodiment of a surface position detecting device of the present invention. It is a schematic structure figure showing a 3rd embodiment of a surface position detecting device of the present invention. It is a schematic diagram which shows a pupil division plate. It is a flowchart figure which shows an example of the manufacturing process of a semiconductor device. FIG. 9 is a schematic diagram for explaining a conventional problem.

Explanation of reference numerals

24: wavelength selection filter, 50: liquid (water, light transmitting member),
100: AF detection device (surface position detection device), EX: exposure device, L1: first detection light,
L2: second detection light, M: mask, P: substrate, PL: projection optical system (light transmitting member),
PLC: imaging characteristic adjusting device, S: surface of substrate (surface to be inspected), θ ₁ : first incident angle,
θ ₂ : second incident angle

Claims (25)

A surface position detection device that detects the surface position of the test surface based on information obtained by projecting the detection light onto the test surface and receiving reflected light from the test surface,
A light transmission system for projecting a plurality of lights as detection light at different angles of incidence onto a surface to be measured;
A light receiving system for receiving light reflected from the surface to be inspected. A surface position detection device for projecting detection light onto a surface to be detected and detecting a surface position of the surface to be detected based on information obtained by receiving reflected light from the surface to be detected, comprising:
A light transmission system for projecting a plurality of lights having different wavelengths onto a surface to be detected as detection light;
A light receiving system for receiving light reflected from the surface to be inspected.   The surface position detecting device according to claim 1, wherein the detection light is projected onto the surface to be detected via a light transmitting member.   The surface position detection device according to claim 3, wherein the detection light is projected onto the surface to be detected via a liquid.   The surface position detection device according to claim 1, wherein the detection light is projected onto the surface to be detected via a liquid.   The pattern of the mask is mounted on an exposure apparatus that exposes the substrate by projecting the pattern on the substrate via a projection optical system, and the test object is used to control a positional relationship between an image plane of the projection optical system and the substrate surface. The surface position detection device according to any one of claims 1 to 5, wherein the detection light is projected onto the surface of the substrate as a surface to detect surface position information of the substrate surface. An exposure method for projecting an image of a pattern of a mask onto a substrate by a projection optical system to expose the substrate, comprising:
Projecting a plurality of detection lights on the substrate surface at different incident angles and receiving reflected light from the substrate surface to detect refractive index information of the detection light and the optical path of the reflected light;
Projecting an image of a pattern of a mask onto a substrate by a projection optical system.   The exposure method according to claim 7, wherein the incident angles θ of the plurality of detection lights each satisfy a condition of 30 ° ≦ θ <90 °.   9. The exposure method according to claim 8, wherein the incident angles θ of the plurality of detection lights each satisfy a condition of 70 ° ≦ θ <90 °. An exposure method for projecting an image of a pattern of a mask onto a substrate by a projection optical system to expose the substrate, comprising:
Projecting a plurality of detection lights having different wavelengths on the substrate surface and receiving the reflected light from the substrate surface, thereby detecting the refractive index information of the detection light and the optical path of the reflected light;
Projecting an image of a pattern of a mask onto a substrate via a projection optical system.   The exposure method according to claim 10, wherein the reflected light from the substrate is detected for each wavelength.   The exposure method according to any one of claims 7 to 11, wherein the refractive index information includes a temperature change of the optical path.   The exposure method according to any one of claims 7 to 12, wherein the detection light is projected onto the surface of the substrate via some optical elements of the projection optical system.   The exposure method according to any one of claims 7 to 13, wherein a positional relationship between an image plane of the projection optical system and the substrate surface is adjusted based on the refractive index information.   15. The surface position of the substrate surface is detected by at least one of the plurality of detection lights, and the detected surface position is corrected based on refractive index information obtained using the plurality of detection lights. Exposure method according to 1.   The exposure method according to any one of claims 7 to 15, wherein a liquid exists between the projection optical system and the substrate surface, and the refractive index information includes refractive index information of the liquid.   The exposure method according to claim 16, wherein the liquid is water.   18. The exposure method according to claim 16, wherein a change in the refractive index of the liquid is detected by receiving the reflected light, and an image adjustment is performed so that an error does not occur in the image of the pattern due to the change in the refractive index of the liquid. . An exposure method for projecting an image of a pattern onto a substrate through a liquid by a projection optical system and subjecting the substrate to immersion exposure, comprising:
Filling at least a portion between the projection optics and the substrate with a liquid;
Optically detecting temperature information of the liquid between the projection optics and the substrate;
Projecting an image of the pattern onto the substrate through a liquid by a projection optical system.   20. The exposure method according to claim 19, further comprising projecting detection light onto the surface of the substrate via the liquid and receiving light reflected from the surface of the substrate via the liquid, thereby detecting temperature information of the liquid. .   21. The exposure method according to claim 19, wherein surface position information of the substrate surface is detected by receiving the reflected light.   22. The exposure method according to claim 19, wherein an image forming state of an image of a pattern projected on the substrate is adjusted based on the temperature information.   23. The exposure method according to claim 19, wherein a temperature of a liquid supplied between the projection optical system and the substrate is controlled based on the temperature information.   21. The exposure method according to claim 20, wherein a change in the refractive index of the liquid is obtained from the received reflected light, and a change in the temperature of the liquid is obtained based on the change in the refractive index. A device manufacturing method using the exposure method according to any one of claims 7 to 24.

Images