JP2008147369A - Surface position measuring apparatus and exposure system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a stage positioning accuracy and compactify a substrate stage, by enabling continuous measurement of a position on a substrate mount surface in the full operational range of the stage. <P>SOLUTION: A surface position measuring apparatus measures a position on the substrate mount surface of a substrate carrying stage with respect to a predetermined surface reference. The apparatus includes a first mirror located separately from the stage to be parallel to the reference surface, a first laser interferometric distance measurement system for measuring a distance between the substrate mount surface and the first mirror, and a second laser interferometric distance measurement system for measuring a distance between the first mirror and the reference surface. The apparatus further includes a means for calculating a position on the substrate mount surface with respect to the reference surface on the basis of a value measured by the first laser interferometric distance measurement system and a value measured by the second laser interferometric distance measurement system. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exposure apparatus that exposes a substrate through an original.

  In recent exposure apparatuses, as the NA of the projection optical system increases, focus and leveling alignment by a wafer stage (also referred to as a substrate stage) is required to have extremely strict accuracy (reproducibility). For example, the depth of focus that can be secured at the time of wafer exposure is about 200 [nm] with a scanning exposure apparatus with NA = 0.93. However, the control accuracy that can be assigned to the focus leveling drive error by removing the error factors such as field curvature, reticle defocus amount, and image plane calibration error from the general empirical rule. It is about 10% (20 [nm]). For this reason, a method of performing control using a laser interferometer with good linearity and high resolution for the position measurement of the Z axis (focus direction) and the leveling axis has been adopted.

For example, it is possible to measure the position of the stage surface in the focus direction by arranging flat mirrors (YZ1, YZ2) on the left and right sides of the upper surface of the wafer stage and reflecting the measurement light from the reference mirrors fixed on both sides of the projection lens in each. It is said.
Further, in Patent Document 1 (Japanese Translation of PCT International Publication No. 2001-510577), measurement light incident horizontally on a lens barrel surface plate with an acute angle mirror disposed on the side surface of a wafer chuck and having a projection lens and an interferometer fixed thereto is used as a projection lens. A method of measuring the height of the wafer chuck by reflecting the laser beam to the side has been proposed.
JP-T-2001-510577

  By the way, in the example where the plane mirrors (YZ1, YZ2) are arranged, the measurement light of the plane mirrors YZ1 and YZ2 is cut off as the wafer stage moves in the Y direction (the measurement light cannot be reflected by the plane mirrors YZ1 and YZ2). ) Therefore, it is necessary to construct a system for switching the Z (focus) current position measurement system. Further, when the Z interferometer is switched, errors due to air fluctuations and deformation factors of the stage top plate accumulate, which makes it difficult to maintain an absolutely stable coordinate system. Further, the measurement in the leveling direction is performed by a pitching interferometer using two measurement lights parallel to the X axis or the Y axis. However, it is not possible to take a wide optical axis span for pitching measurement due to the necessity of reducing the stage size. For this reason, it is no longer possible to ignore factors that cause deterioration in pitching measurement accuracy due to air fluctuation and resolution roughness.

On the other hand, in Patent Document 1, the two interferometer measurement lights arranged between the Z measurement mirror and the Z reflector for measuring in the Z direction are not cut off at any position of the stage during the exposure process. It has become. However, as indicated by the inventor's view of Patent Document 1, in order to configure the Z measurement mirror so that the measurement light is not cut off, it is necessary to enlarge the dimension (h) of the substrate holder including the Z measurement mirror. There is. This may hinder the improvement of the stage dynamic characteristics and the footprint design of the exposure apparatus. In particular, when the lens diameter increases as NA increases, it is particularly important to deal with this problem.
An object of the present invention is to provide a novel technique for measuring the position of a substrate stage in the direction of the optical axis of a projection optical system in view of the above problems.

  A surface position measuring device for solving the above problem is a surface position measuring device that measures a position of a substrate mounting surface of a stage on which a substrate is mounted with respect to a predetermined reference surface. The surface position measuring apparatus of the present invention measures the distance between the first mirror separated from the stage and disposed in parallel with the reference surface, and the distance between the substrate mounting surface and the first mirror. A laser interference length measuring system; and a second laser interference length measuring system for measuring a distance between the first mirror and the reference plane. Furthermore, a calculation means is provided for calculating a position of the substrate mounting surface with respect to the reference surface based on a measurement value obtained by the first laser interference measurement system and a measurement value obtained by the second laser interference measurement system. As the reference plane, for example, a design or ideal substrate mounting surface, or an image plane of the projection optical system may be set in the case of an exposure apparatus.

  The exposure apparatus of the present invention is an exposure apparatus that exposes a substrate through an original, and is characterized by the following. That is, a projection optical system that projects light from the original onto the substrate, a first surface plate that supports the projection optical system, a substrate stage that holds and moves the substrate, and a substrate stage. And a second surface plate that supports the substrate stage. In addition, with respect to the second surface plate, a second mirror disposed on the side opposite to the substrate stage, supported by the first surface plate, and in the direction of the optical axis of the projection optical system, And a first laser interferometer that measures the position of the first mirror with respect to the second mirror. And a second laser interferometer that is supported by the first surface plate and measures the position of the second mirror with respect to the first surface plate in the direction of the optical axis. Then, based on the measurement value by the first laser interferometer and the measurement value by the second laser interferometer, the position of the substrate stage with respect to the first surface plate in the direction of the optical axis is calculated.

  According to the present invention, for example, a novel technique for measuring the position of the substrate stage in the direction of the optical axis of the projection optical system can be provided.

  An exposure apparatus according to a preferred embodiment of the present invention is an exposure apparatus that exposes a substrate through an original and a projection optical system, and a surface position measurement apparatus that measures the height and inclination of a wafer chuck (substrate mounting surface). Is provided. The surface position measuring apparatus includes a reflection mirror (first mirror, indirect reference mirror) that is separated from the wafer stage structure (stage) and is mounted in parallel to the wafer chuck surface, and the indirect reference mirror and wafer chuck. And a first laser interference length measuring system for measuring the distance. Further, a second laser interference length measuring system is provided for measuring the distance between the indirect reference mirror and the structure (PO surface plate, reference plane) serving as the apparatus reference. The indirect reference mirror measures the relative distance and posture of the reflecting mirror provided on the back surface of the wafer chuck or a reflecting member similar to the reflecting mirror by the first laser interference length measuring system.

  According to the present embodiment, the reflection mirror that reflects the measurement optical axis of the laser interferometer for measuring the Z and tilt axes of the wafer stage to the wafer stage surface plate side, and the measurement optical axis as the pickup side of the laser interferometer An indirect reference mirror is provided on the stage surface plate side. Thereby, a continuous Z and tilt axis measurement system of the wafer stage in the work range can be provided. At the same time, in realizing a continuous Z and tilt axis measurement system of the wafer stage, a smaller wafer stage system can be constructed as compared with the conventional example.

Hereinafter, preferred embodiments of the present invention will be described based on examples shown in the accompanying drawings.
In the following embodiments, for convenience of explaining the effects of the present invention, an exposure apparatus provided with two wafer stages will be taken as an example. However, even when the present invention is applied to an exposure apparatus having a single stage configuration, the same will be described below. It is clear that an effect can be obtained.

[First embodiment]
1 to 3 show the arrangement of an exposure apparatus according to the first embodiment of the present invention. In the illustrated exposure apparatus, the movement space of the wafer stage 7 is composed of an exposure station (FIG. 1) that performs wafer exposure and a measurement station (FIG. 2) that collectively performs wafer alignment measurement and focus tilt measurement. . FIG. 3 is a top view of the stage surface plate 2 on which the two wafer stages 7 (7a, 7b) move. Although the wafer stage 7 is indicated by 7a in FIG. 1 and 7b in FIG. 2, both of them move between the exposure station (FIG. 1) and the measurement station (FIG. 2).

  In FIG. 1, reference numeral 1 denotes a base frame disposed in contact with the floor surface, and all components on the exposure apparatus main body are mounted on the base frame 1. Reference numeral 2 denotes a stage surface plate, which is vibrationally insulated and held in a predetermined frequency range of interest by the active damper 14 with respect to the base frame 1. The stage surface plate 2 also serves as a planar guide in the coarse movement portion of the wafer stage 7a. Further, the stage surface plate 2 receives a load of the wafer stage 7a according to the wafer stage position coordinates, and deforms or changes its posture by several μm. The reaction force caused by the step in the XY direction of the wafer stage 7a is applied to a counter mass (not shown) to cancel the momentum.

  Reference numeral 3 denotes a lens barrel surface plate (PO surface plate), which is a structure that provides a reference for the coordinate system of the apparatus. That is, the wafer stage laser interferometer pickups 10 a and 10 c, the reticle laser interferometer pickup 16, and the reticle focus measuring instrument 15 that measures the focus leveling of the reticle are formed on the lens barrel surface plate 3. Since the lens barrel surface plate 3 needs to block vibration from the floor surface, it is supported from the base frame 1 by the active damper 28 like the stage surface plate. Reference numeral 4 denotes a projection lens, which reduces and projects a pattern image drawn on the reticle 17 onto the wafer surface. The projection lens 4 is supported by the outer cylinder 9.

  In recent cases, a drive shaft for correcting and driving the lens formed in the projection lens 4 has been mounted to correct lens aberration. Therefore, in order to prevent the vibration of the projection lens 4 from being transmitted to the lens barrel base plate, a holding method in which the projection lens 4 is vibrationally isolated from the lens barrel base plate has been adopted.

  Reference numeral 13 denotes an immersion nozzle for filling a gap between the wafer held on the wafer stage 7a and the projection lens 4 with a liquid such as pure water. Reference numeral 17 denotes a reticle stage that holds the reticle. In the scanning exposure apparatus, the wafer stage 7a is scanned in synchronism with the scanning operation of the reticle stage 17 (in this embodiment, scanning in the front and back directions with respect to the paper surface), and the pattern on the reticle is transferred and exposed onto the wafer. . Reference numeral 18 denotes an alignment beam projecting element that irradiates a reticle or a lattice mark drawn on the reticle stage 17. By measuring this lattice mark while scanning a small area in the XY direction or the Z direction with a sensor (not shown) (hereinafter referred to as LIPS sensor) provided on the wafer stage 7a, the amount of deviation from the reference position in the three-axis direction is measured. It can be measured. By performing the same measurement using sensors provided at a plurality of different positions on the wafer stage 7a, the coordinates of the six axes related to the wafer stage 7a can be accurately aligned.

  2 is stored as a function or a table for each position in the wafer surface, with respect to a wafer whose alignment and shape are measured by the measurement station described in FIG. 2 and a relative position with a reference mark (not shown) fixed on the wafer stage 7. The wafer transferred to the exposure station together with the wafer stage 7 measures the relative position between a sensor (not shown) fixed on the wafer stage 7a and a reticle or a lattice mark drawn on the reticle stage, like the reference mark. As a result, the relative relationship between the alignment mark on the reticle and the alignment mark on the wafer in six axes is determined.

  Reference numerals 19 and 20 respectively denote a first condenser optical element unit and a second condenser optical element unit for shaping exposure light that illuminates the reticle. Reference numeral 21 denotes an exposure slit, which is disposed at a position that is a conjugate plane with respect to the reticle pattern surface. Reference numeral 22 denotes a masking blade that prevents exposure light from hitting an irrelevant reticle area drawn on the reticle beyond the shading zone. The masking blade 22 scans in the Z direction in synchronization with the scanning operation of the reticle stage 17 and the wafer stage 7a.

  Laser interferometer pickups 10a and 10c are supported from a lens barrel surface plate. In the present embodiment, the laser interferometer pickup 10c on the right side irradiates the X mirror 24a mounted on the wafer stage 7a with measurement light 12a for measuring the distance in the X direction of the wafer stage 7a to indicate the current position in the X direction. It has gained. The laser interferometer pickups 10a and 10c irradiate the bending mirror 8a mounted on the wafer stage with measurement light 11a for measuring the distance in the Z direction so that the relative distance from the indirect reference mirror 5a can be measured. It has become.

Reference numeral 23a denotes a through hole provided in the stage surface plate 2 in the exposure station, and passes through measurement optical axes 11a and 25a of an interferometer that performs Z-direction measurement. An example of this aspect is shown in FIG. On the other hand, the indirect reference mirror 5a may be disposed at the bottom by digging down the indirect reference mirror portion of the stage surface plate without needing to make a hole in the stage surface plate 2. An example of this aspect is shown in FIG. As another example, the stage surface plate 2 may be made of a transparent material such as glass in order to pass the measurement optical axis of the laser interferometer.
The surface of the stage surface plate 2 can be used as a mirror surface instead of the indirect reference mirror 5a. However, according to this method, since the load position applied to the stage surface plate 2 varies depending on the position of the wafer stage 7a, the indirect reference mirror is deformed depending on the stage coordinates. In order to compensate for this, a correction mechanism and an adjustment process corresponding to the stage coordinates are required.

  Returning to the description of FIG. 1, the position of the indirect reference mirror 5a in the Z direction is also measured by the measurement light 25a dropped from the left and right laser interferometer pickups 10a and 10c provided on the lens barrel surface plate. In order to prevent the indirect reference mirror from being affected by the deformation of the stage surface plate 2 when the load of the wafer stage 7 is moved, the indirect reference mirror may be provided separately as in the present embodiment, or the stage may be used in consideration of vibration from the floor. You may support from the back of the surface plate. What is important is that the position variation and the angle variation of the indirect reference mirror are allowed, but the mirror deformation causes a measurement error. Therefore, it is desirable that the indirect reference mirror is designed to be rigid and is held using flexible support members 6a and 6b.

When supporting from the back surface of the stage surface plate, the indirect reference mirror 5a is attached to the stage surface plate 2 via the support members 6a and 6b. By measuring the position and orientation of the indirect reference mirror 5a from the laser interferometer pickups 10a and 10c, if the indirect reference mirror 5a is substantially stationary with respect to the lens barrel surface plate 3, the orientation is affected by floor vibration or the like. Even when the position fluctuates, the fluctuation can be measured correctly, so that the relative distance between the wafer stage 7 and the lens barrel surface plate can be measured accurately.
A method for obtaining the coordinates of the Z axis and the leveling axis of the wafer stage using the indirect reference mirror will be described in the description of FIG.

  According to the present embodiment, position information from measurement light projected from the laser interferometer pickups 10a and 10c on both sides is always obtained in all strokes used for exposure in the exposure station. Therefore, the interferometer switching error at the wafer stage position is eliminated, and good pitching axis measurement accuracy in the ωy direction can be obtained. Although not disclosed in FIGS. 1 to 3 regarding pitch measurement in the ωx direction, if a plurality of pairs of the laser interferometer pickup 10 and the indirect reference mirror 5 are arranged apart in the Y direction, the same is true in pitching measurement accuracy in the ωx direction. The effect is obtained. However, the exposure slit used for scanning exposure has a shape that is long in the X direction and short in the Y direction, while the scanning direction is the Y direction. Therefore, the required accuracy for control of the ωx axis is not as strict as ωy, and it is considered that the required performance can be sufficiently achieved with the measurement accuracy of the pitching measurement optical axis applied from the laser interferometer pickups 304a and 304b (see FIG. 3).

  FIG. 9 is an explanatory diagram for explaining a coordinate calculation method for the Z and ωy axes of the Z axis measurement system in the first embodiment of the present invention. In the components shown in the drawing, the interference is measured in the horizontal direction from the interferometer pickups 10a and 10c, bent 90 degrees in the Z direction by the mirror 8 at the wafer stage 7a, and reflected by the indirect reference mirror 5a. Let the current position of the meter be ZL and ZR, respectively. These are the height of the wafer surface and the ωy direction when the wafer chuck center of the wafer stage is located at the intersection of the interferometer 12a (Y axis is not shown) that performs XY measurement with the indirect reference mirror maintained at the neutral point. A specific orientation in which the inclination of the image is approximately parallel to the image plane is defined as the coordinate origin. Also, let X be the distance in the X direction of the wafer stage 7a, where the origin is where the center of the wafer chuck is located at the intersection of the interferometer 12a that measures the XY direction of the wafer stage 7a. The 90-degree reflecting mirrors 8 attached to both sides of the wafer stage 7a are attached at equal intervals (1/2 WS) from the center of the wafer chuck. Also, let RL and RR be the current positions of the interferometers that measure the optical path length that is dropped vertically from the interferometer pickups 10a and 10c in the Z direction and measures the indirect reference mirror 5a. The span length of the measurement spot where RL and RR are dropped is WR. The origins of RL and RR are defined as the origin when the indirect reference mirror 5a is positioned at a predetermined neutral point. Based on this definition, the current position (Z, ωy) of the wafer chuck center of the wafer stage 7a can be obtained by the following equation.

Ｃｃｍｐｚ、Ｃｃｍｐｑｙは、レーザ干渉計の組み立て公差やミラーの理想平面からの凹凸変動量を補正するためのＡＢＢＥ補正パラメータおよびミラーベンド補正テーブルである。これらのパラメータはウエハステージのＸＹ座標やθ座標に関連して補正値が変動するため、多項式や補正テーブルなどによって補正計算が行われ、その計算結果が現在位置に加算されて補正が行われるのが一般的である。
間接参照ミラー５ａ、５ｂは重力による撓みや加工精度による表面荒さによって、理想的な平面ではないため、上記補正（Ｃｃｍｐｚ、Ｃｃｍｐｑｙ）は必須である。

Ccmpz and Ccmpqy are ABBE correction parameters and a mirror bend correction table for correcting the assembly tolerance of the laser interferometer and the uneven fluctuation amount from the ideal plane of the mirror. Since the correction values of these parameters fluctuate in relation to the XY coordinates and θ coordinates of the wafer stage, correction calculation is performed using a polynomial or a correction table, and the calculation result is added to the current position to be corrected. Is common.
Since the indirect reference mirrors 5a and 5b are not ideal planes due to the bending due to gravity and the surface roughness due to processing accuracy, the above correction (Ccmpz, Ccmpqy) is essential.

Ｏｙは、ステージをＸ方向に駆動したときのステージ走り面を補正する補正係数、Ｆｚｘ（Ｘ）は、間接参照ミラー５ａのミラー平面度のＺ成分補正テーブル、Ｆｚｙ（Ｙ）は、ウエハステージ７ａの反射ミラー８平面度のＺ成分補正テーブルである。ＣｘはウエハステージをＸ方向に駆動した時のωｙ軸干渉成分の一次係数であり、間接参照ミラー５ａが放物線形状の弓なりを持っていると発生する。Ｃｑはウエハステージをθ方向に駆動した場合のωｙ軸干渉成分の一次係数、Ｆｑｘ（Ｘ）は、間接参照ミラー５ａのミラー平面度のωｙ成分補正テーブル、Ｆｑｙ（ｙ）は、ウエハステージ７ａの反射ミラー８平面度のωｙ成分補正テーブルである。

Oy is a correction coefficient for correcting the stage running surface when the stage is driven in the X direction, Fzx (X) is a Z component correction table of mirror flatness of the indirect reference mirror 5a, and Fzy (Y) is a wafer stage 7a. This is a Z component correction table for the flatness of the reflecting mirror 8. Cx is a first-order coefficient of the ωy-axis interference component when the wafer stage is driven in the X direction, and is generated when the indirect reference mirror 5a has a parabolic bow. Cq is the primary coefficient of the ωy-axis interference component when the wafer stage is driven in the θ direction, Fqx (X) is the ωy component correction table of the mirror flatness of the indirect reference mirror 5a, and Fqy (y) is the wafer stage 7a. It is a ωy component correction table of reflection mirror 8 flatness.

  According to this embodiment, the laser interferometer measurement light 11a for Z-axis measurement is reflected toward the wafer stage surface plate 2 by the 90-degree reflection mirror 8a attached to the wafer stage 7a, and the back surface of the wafer stage surface plate 2 is reflected. The relative distance from the indirect reference mirror 5a arranged on the side is measured. On the other hand, the indirect reference mirror 5a is held by a flexible support component 6a that does not transmit floor vibration or surface plate deformation from the stage base frame 1 or the stage surface plate 2, and the relative distance between the indirect reference mirror 5a and the interferometer pickup 10 is determined. By measuring, the relative distance between the interferometer pickup 10 fixed on the lens barrel surface plate serving as a measurement reference and the Z of the wafer stage is obtained by calculation. Since the displacement and the posture variation of the indirect reference mirror 5a are canceled in the above equation (1), no error is given to the Z-axis measurement or the tilt-axis measurement. In addition, since there is no need to place a measurement optical axis by a laser interferometer above the upper surface of the wafer chuck, there is an advantage that the degree of freedom in design is improved when a projection lens having a large NA is arranged at the top.

[Second Embodiment]
In the above description, the present invention is applied to the exposure station of the exposure apparatus. However, the present invention can also be applied to the measurement station of FIG. In FIG. 2, the serial numbers having the same numerical values as those in FIG. 1 are members common to the exposure station. Further, members having the same number excluding the alphabet are also members common to FIG. The optical axis routing of the laser interferometer and the configuration of the stage 7 are the same as those described in FIG. Further, the coordinate calculation method for the Z and ωy axes of the Z axis measurement system is also common.

  In FIG. 2, 201 is a compound eye focus sensor that measures the position in the focus (Z) direction on the wafer, and 202 is an alignment sensor that measures the alignment marks in the XY direction of the wafer chucked on the wafer stage 7. In the measurement station, the wafer stage 7 is driven and the alignment sequence is performed while the alignment sensor 202 is positioned at the coordinates of a predetermined alignment measurement sample shot. The position of a reference mark (not shown) on the wafer stage is measured before or after the alignment sequence, and the relative distance between the reference mark and the alignment mark on the wafer is calculated and stored. Similarly, with respect to the focus leveling direction, the wafer stage 7 is driven to perform focus measurement using the focus sensor 201, and the relative distance relationship with a reference mark (not shown) is measured and stored before or after the sequence.

[Third embodiment]
FIG. 3 is a view of the stage surface plate 2 of the exposure apparatus in which the present invention is applied to both the exposure station and the measurement station, and FIG. 4 is a view of the stage surface plate shown in FIG. 3 viewed from the side. . The laser interferometer pickups 10a to 10d are fixed to the lens barrel surface plate 3 (see FIGS. 1 and 2) and are not in direct contact with the wafer stage surface plate 2. Reference numerals 304a and 304b denote laser interferometer pickups for measuring the positions of the two wafer stages 7a and 7b in the Y-axis direction and the ωx direction, respectively. Reference numeral 301 denotes the position of the projection lens 4 on the exposure station side, and 302 denotes the position of the alignment and focus measuring instrument 201 on the measurement station side.

  The wafer stages 7a and 7b exchange positions after the jobs to be performed at the respective positions are completed. That is, the wafer stage 7b that has completed the alignment and focus measurement of the sample wafer at the measurement station waits until the processing of the wafer stage 7a that is performing the exposure process at the exposure station is completed, and is swapped. The wafer after the exposure process is transferred to the measurement station and unloaded. While the wafer stage is swapped, the optical axes of the laser interferometers 10a to 10d and 304a and 304b are blocked, and all position measurement information by these interferometers is indefinite. The position measurement by the laser interferometer of each of the wafer stages 7a and 7b is restored after the rough origin is automatically performed when the swap is completed, and the precise origin is performed under the position control by the interferometer. The measurement by the alignment beam projector 18 described with reference to FIG. 1 corresponds to the precise origination at the exposure station here. In the measurement station, the precise origin is performed by the alignment scope 202 and the focus measurement sensor 201.

  FIG. 5 describes a layout when the two wafer stages 7a and 7b are swapped in the third embodiment. When the present invention is applied, the width in the X direction of the wafer stages 7a and 7b is estimated to be about 400 to 450 mm when a 12-inch wafer chuck is mounted.

FIG. 6 is a structural diagram of the wafer stage 7 (7a, 7b) in the first to third embodiments. The wafer stage 7 is composed of a coarse movement stage 708 having a large stroke in the XY directions and a fine movement stage 708 which is driven on the coarse movement stage and can be driven in a minute amount of six axes. On the fine movement stage, a wafer chuck 705 and a reference mark plate which is a substrate on which a mark observable with an alignment scope (not shown) is mounted are fixed. Further, a LIPS sensor (not shown) that performs alignment and focus measurement while scanning a small area in the XY direction or Z direction at the exposure station is also fixed. Reference numerals 701 and 702 denote linear motors for driving the fine movement stage.
The coarse movement stage 708 is driven by a flat pulse motor 703, and floats slightly from the stage surface plate by an air bearing 704.

  In addition to the above configuration, the following configuration can also be used. That is, the driving force generation mechanism 703 in the coarse movement stage 707 is eliminated, and the drive guide mechanism outside the stage is connected to the coarse movement stage 707. In the stage swap, by exchanging the connection of the drive guide mechanism, the unit above the coarse movement stage 707 can come and go between both stations while arranging the drive guide mechanism for each exposure station and measurement station. To do. Even with such a configuration, the present invention can be applied.

[Fourth embodiment]
FIG. 10 shows an exposure station configuration of an exposure apparatus according to the fourth embodiment of the present invention. In FIG. 10, the same numbers as those in FIG. The difference from the first embodiment is that the reflecting mirror 901 in FIG. 10 is formed on the back surface of the wafer chuck in parallel to the XY plane in contrast to the reflecting mirror 8a in FIG. The Z-axis measuring beams 904a and 904b of the wafer stage are emitted from a laser interferometer pickup unit described with reference to FIG. Reference numeral 902 denotes a half mirror, which corresponds to the indirect reference mirror 5a in FIG. The half mirror 902 reflects the reference measurement beams 905a and 905b and transmits the measurement beams 904a and 904b. The measurement value of the Z-axis interferometer is the difference between the optical paths 904 and 905, and this is the relative value between the half mirror 902, which is an indirect reference mirror, and the reflection mirror 901 on the back of the wafer stage. The relationship between the measurement light beams 25a and 25b emitted downward from the laser interferometer pickups 10a and 10b and the half mirror 902 is the same as that of the indirect reference mirrors 5a and 5b in the first embodiment.

FIG. 11 is an explanatory diagram of a laser interferometer pickup (hereinafter referred to as a movable pickup) movable in the X direction in the fourth embodiment. The movable pickup is equipped with a laser interferometer 1001, from which Z-axis measurement light 904 a, 904 b, 905 a, and 905 b are emitted in the normal direction with respect to the paper surface and reflected by the mirrors described in FIG. 10. Returned. Reference numeral 1002 denotes a pickup stage that drives the movable pickup in the X-axis direction. The drive accuracy of the pickup stage is not required to be so strict.
Thus, even in the configuration shown in the fourth embodiment, the Z and ωy axis measurement system using the indirect reference mirror according to the present invention can be configured.
Note that this embodiment can also be applied to a measurement station in the same manner as shown in the first to third embodiments.

  According to the above-described embodiment, the reflection mirror that reflects the measurement optical axis of the laser interferometer for measuring the Z and tilt axes of the wafer stage to the wafer stage surface plate side, and the measurement optical axis is picked up by the laser interferometer. An indirect reference mirror that reflects to the side is provided on the stage surface plate side. Thereby, a continuous Z and tilt axis measurement system of the wafer stage in the work range can be provided. At the same time, in realizing a continuous Z and tilt axis measurement system of the wafer stage, it is possible to construct a wafer stage system that is smaller than the conventional example.

[Fifth embodiment]
Next, a manufacturing process of a microdevice (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.) using the above-described exposure apparatus will be described.
FIG. 12 shows a flow of manufacturing a semiconductor device.
In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask production), a mask (also referred to as an original plate or a reticle) on which the designed pattern is formed is produced.
On the other hand, in step 3 (wafer manufacture), a wafer (also referred to as a substrate) is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the wafer and the exposure apparatus provided with the prepared mask.
The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer manufactured in step 4. The post-process includes assembly processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.

  The wafer process in step 4 includes an oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, and an electrode formation step for forming electrodes on the wafer by vapor deposition. Also, an ion implantation step for implanting ions into the wafer, a resist processing step for applying a photosensitive agent to the wafer, and an exposure step for exposing the wafer after the resist processing step through a mask having a circuit pattern using the exposure apparatus described above. Have. Further, there are a development step for developing the wafer exposed in the exposure step, an etching step for removing portions other than the resist image developed in the development step, and a resist stripping step for removing the resist that has become unnecessary after the etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

It is a figure which shows the structure of the exposure station of the exposure apparatus which concerns on 1st Example of this invention. It is a figure which shows the structure of the measurement station of the exposure apparatus which concerns on 2nd Example of this invention. It is the figure which looked at the stage surface plate 2 of the exposure apparatus to which the exposure station and measurement station which concern on 3rd Example of this invention were applied from the upper surface. It is the figure which looked at the stage surface plate shown in FIG. 3 from the side. FIG. 4 is a layout diagram when two wafer stages are swapped in the exposure apparatus of FIG. 3. FIG. 4 is a structural diagram of a wafer stage in the exposure apparatus of FIGS. 1 to 3. It is explanatory drawing of the through-hole provided in the stage surface plate in the exposure apparatus of FIGS. It is a figure which shows the modification of the arrangement | positioning method of the indirect reference mirror in the exposure apparatus of FIGS. It is explanatory drawing explaining the coordinate calculation method of Z and the ωy axis of the Z axis measurement system in the exposure apparatus of FIGS. It is a figure which shows the structure of the exposure station of the exposure apparatus which concerns on 4th Example of this invention. It is explanatory drawing of the laser interferometer pickup which can move to the X direction in FIG. It is a figure explaining the flow of the manufacturing process of a device.

Explanation of symbols

1 Base frame 2 Stage surface plate 3 Lens barrel surface plate (PO surface plate)
4 Projection lens 5a, 5b Indirect reference mirror 6a, 6b Flexible support member 7a, 7b Wafer stage (W / S)
8a, 8b Bending mirrors mounted on the wafer stage 10a-10d Laser interferometer pickups 11a, 11b Laser interferometer measurement optical axes 12a, 12b used for Z axis and tilt axis measurement Laser interferometer measurement used for XY axis measurement Optical axes 23a and 23b Through holes 25a and 25b provided in the wafer stage Interferometer measuring optical axes for measuring the relative distance between the laser interferometer pickup and the indirect reference mirror

Claims (19)

A surface position measuring device for measuring a position of a substrate mounting surface of a stage on which a substrate is mounted with respect to a predetermined reference surface,
A first mirror separated from the stage and disposed in parallel with the reference plane;
A first laser interference measurement system for measuring a distance between the substrate mounting surface and the first mirror;
A second laser interference measurement system for measuring a distance between the first mirror and the reference plane;
And a calculation means for calculating a position of the substrate mounting surface with respect to the reference surface based on a measurement value obtained by the first laser interference measurement system and a measurement value obtained by the second laser interference measurement system. Position measuring device.   2. The first laser interference length measuring system measures a relative distance between the first mirror and a reflecting member provided on a back surface of a chuck that holds a substrate on the stage. The surface position measuring device described.   The surface position measuring apparatus according to claim 1, wherein the first mirror is provided on a plane guide that guides the stage in a direction parallel to the reference surface.   The surface position measuring apparatus according to claim 3, wherein the planar guide also serves as the first mirror.   The surface position measuring device according to claim 3, wherein the first mirror is supported by the planar guide.   The surface position measuring apparatus according to claim 3, wherein the first mirror is embedded in the planar guide.   The surface position measuring apparatus according to claim 5, wherein the first mirror is held by the planar guide via a flexible member.   The first mirror relates to a planar guide that guides the stage in a direction parallel to the reference plane, and is disposed on the opposite side of the stage, and the planar guide transmits measurement light of the first laser interferometer length measurement system. The surface position measuring device according to claim 1, further comprising a transmission groove for transmitting light.   The first mirror relates to a planar guide for guiding the stage in a direction parallel to the reference plane, and is disposed on the opposite side of the stage, and the guide guide transmits measurement light of the first laser interference length measurement system. The surface position measuring device according to any one of claims 1 to 7, wherein the surface position measuring device is made of a material to be used.   10. The first mirror according to claim 1, wherein the first mirror is a half mirror that reflects reference light from a laser interferometer pickup of the first laser interference measurement system and transmits measurement light. The surface position measuring device described in 1.   The laser interference length measurement system measures a relative distance between at least two of each of the reference surface, the substrate mounting surface, and the first mirror. Surface position measuring device.   The surface position measurement apparatus according to claim 11, wherein the calculation unit also performs measurement for further calculating a tilt component of the substrate mounting surface based on a relative distance between the at least two locations. An exposure apparatus that exposes a substrate mounted on a substrate stage via an original and a projection optical system,
An exposure apparatus that measures the position of the substrate mounting surface of the substrate stage using the surface position measurement apparatus according to claim 1. An exposure apparatus that exposes a substrate through an original plate,
A projection optical system for projecting light from the original onto the substrate;
A first surface plate that supports the projection optical system;
A substrate stage for holding and moving the substrate;
A first mirror disposed on the substrate stage;
A second surface plate for supporting the substrate stage;
A second mirror disposed on the opposite side of the substrate stage with respect to the second surface plate;
A first laser interferometer that is supported by the first surface plate and measures the position of the first mirror with respect to the second mirror in the direction of the optical axis of the projection optical system;
A second laser interferometer that is supported by the first surface plate and measures the position of the second mirror with respect to the first surface plate in the direction of the optical axis;
Have
Calculating the position of the substrate stage relative to the first surface plate in the direction of the optical axis based on the measured value by the first laser interferometer and the measured value by the second laser interferometer;
An exposure apparatus characterized by that. A plurality of the first laser interferometer and the second laser interferometer, respectively;
An inclination of the substrate stage with respect to the first surface plate is calculated based on measurement values obtained by the plurality of first laser interferometers and measurement values obtained by the plurality of second laser interferometers.
The exposure apparatus according to claim 14, wherein:   The second surface plate has either an opening or a light transmitting portion through which either the measurement light of the first laser interferometer or the measurement light of the second laser interferometer passes. The exposure apparatus according to claim 14 or 15, characterized in that:   The exposure apparatus according to claim 14, wherein the second mirror includes a half mirror. A first sensor for measuring the position of an alignment mark on the substrate held by the substrate stage;
A second sensor for measuring the surface shape of the substrate held on the substrate stage;
Have
The first laser interferometer and the second laser interferometer include an exposure station in which the projection optical system is disposed, and a measurement station in which the first sensor and the second sensor are disposed, Are each arranged,
The exposure apparatus according to claim 14, wherein A step of exposing the substrate using the exposure apparatus according to claim 13;
Developing the exposed substrate;
A device manufacturing method comprising:

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