JP2006269669A - Measuring apparatus and measuring method, exposure apparatus and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the degradation of focus precision due to a change in reflection factor of an object to be measured such as a wafer or the like without reducing throughput as much as possible. <P>SOLUTION: The measuring device is provided with a plane position measuring means to measure the position of a plane to be measured, a reflection factor measuring means to measure the reflection factor of the plane to be measured, and a parameter optimization means which optimizes the measuring parameters of the plane position measuring means on the basis of the reflection factor distribution of the plane to be measured that is obtained by the reflection factor measuring means. The plane position measuring means uses the optimized measuring parameters to measure the position of the plane to be measured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for measuring a wafer surface position to obtain the best image performance, for example, mounted in an exposure apparatus used when a semiconductor element, a liquid crystal display element, a thin film magnetic head or the like is manufactured in a lithography process. It is.

  When a semiconductor element, a liquid crystal display element, a thin film magnetic head or the like is manufactured in a lithography process, an image of a mask or a reticle (hereinafter, collectively referred to as “reticle”) is formed on a photosensitive substrate via a projection optical system. A projection exposure apparatus is used.

  In recent years, along with miniaturization of the processing line width due to high integration of semiconductor elements, the NA of the projection lens in the projection exposure apparatus, the shortening of the wavelength of the light source used, and the enlargement of the screen are progressing. As a means to achieve these, the exposure area has a rectangular slit shape, compared to a so-called "stepper", which is a method of collectively projecting exposure by reducing an exposure area close to a square shape on the wafer. A scanning exposure apparatus, commonly referred to as a “scanner”, which exposes a large screen with high accuracy by relatively scanning at high speed is becoming mainstream.

  In the scanner, since the surface shape of the wafer can be adjusted to the optimum exposure image plane position in units of scanning exposure slits, the influence of wafer flatness can be reduced.

  Also, in the scanner, in order to align the wafer surface with the exposure image plane position in real time during the scanning exposure for each scanning exposure slit, the wafer surface position is set in advance to the surface position of the light oblique incidence system before reaching the exposure slit. A technique of performing drive correction by measuring with a detecting means is used.

In particular, in the longitudinal direction of the exposure slit, that is, in the direction orthogonal to the scanning direction, a plurality of measurement points are provided to measure not only the height but also the surface inclination. The focus / tilt measurement method in the scanning exposure is described in Patent Document 1 and the like.
Japanese Patent Laid-Open No. 06-260391 Japanese Patent Laid-Open No. 10-239015

  Recently, the depth of focus has become extremely small in accordance with the trend toward miniaturization, and so-called focus accuracy, that is, the accuracy of aligning the wafer surface to be exposed to the best imaging plane has become increasingly severe.

  In particular, the measurement error due to the influence of the pattern on the wafer and the defacement of the surface position detection system due to uneven thickness of the resist cannot be ignored. That is, in the vicinity of the peripheral circuit pattern and the scribe line, it is smaller than the depth of focus as shown in the figure, but for focus measurement, a large step is generated and the inclination angle of the resist surface is increased. The reflected light of the position detection system is deviated from the regular reflection angle due to reflection or refraction, or a difference in reflectance occurs between a dense pattern and a rough pattern due to a difference in density of the wafer pattern. As described above, since the reflection angle and reflection intensity change depending on the wafer pattern, the detection waveform that receives the reflected light has an asymmetry that causes a detection error and cannot accurately detect the surface position. Will occur.

  If the wafer surface position is measured in such a state, the surface position cannot be measured in the middle of the exposure, and the exposure stops or a large defocus occurs, resulting in a chip defect. there were.

  A countermeasure against such a wafer uneven reflectance is described in Patent Document 2. Here, a method for dealing with the uneven reflectance will be described with reference to FIG.

  FIG. 18A shows an example in which a sinusoidal signal is distorted due to the influence of uneven reflectance of the wafer, where the horizontal axis represents the position on the light receiving sensor and the vertical axis represents the light intensity. On the other hand, FIG. 18B shows a measurement value of the reflectance distribution of the wafer, which is obtained by receiving the reflected light that is irradiated on the same position on the wafer with the illumination light of uniform intensity. The corrected signal shown in FIG. 18C is obtained by dividing the signal waveform in FIG. 18A by the measurement result in FIG. 18B. That is, when the intensity of each pixel of the signal before correction is I1 (j) where j is the pixel number and the intensity of each pixel of the reflectance distribution measurement value is I2 (j), Intensities I3 (j) and I1 (j) / I2 (j) are calculated for all pixels. The use of this method has an effect that the measurement error due to the uneven reflectance of the wafer can be corrected to some extent, but the following problems remain. In other words, if calculation is performed between each pixel at each measurement point, calculation time increases and throughput is reduced. In particular, in the case of a scanner, the shape of the wafer surface at multiple points in a shot is measured during scanning. Therefore, it is necessary to control after waiting for the calculation result, and it becomes necessary to lower the set speed of the wafer / reticle stage, and the problem that the production speed of the semiconductor is lowered remains.

  The present invention has been made in view of the above problems, and an object of the present invention is to improve focus accuracy deterioration due to uneven reflectance of a measurement object such as a wafer without reducing throughput as much as possible.

  In order to solve the above problems and achieve the object, the measuring apparatus and measuring method according to the first aspect of the present invention include a surface position measuring means or process for measuring the position of the surface to be measured, and the reflectance of the surface to be measured. Parameter optimization for optimizing measurement parameters in the surface position measuring means or process based on the reflectance distribution of the surface to be measured measured in the reflectance measuring means or process The surface position measuring means or step measures the position of the surface to be measured using the optimized measurement parameter.

  In the above aspect, the parameter optimization means or step determines the offset E based on the relationship between the reflectance distribution determined in advance and the measurement offset E in the surface position measurement means or step, and the surface A position to be measured is determined by correcting the measured value in the position measuring means or process with the offset E.

  In the above aspect, in the surface position measuring means or step, a first illuminating means or step for irradiating a surface to be measured with a slit-like pattern, and a detecting means or step for receiving reflected light from the surface to be measured. The reflectance measurement means or process has a second illumination means or process for irradiating illumination light having the same wavelength, incident angle, and polarization state as the illumination light in the first illumination means or process. .

  In the above aspect, the reflectance measuring means or step receives reflected light from the surface to be measured, measures the reflectance distribution and the phase distribution, and calculates the measurement offset E in the surface position measuring means or step. The reflectance distribution and the phase distribution are used.

  Moreover, in the said aspect, the optical simulation based on the measured value in the said reflectance measurement means or a process is used for calculation of the said offset E. FIG.

  Moreover, in the said aspect, the measurement value and exposure result in the said reflectance measurement means or process are used for calculation of the said offset E. FIG.

  Further, in the above aspect, the surface position measuring means or step irradiates light of a plurality of wavelengths to detect the position of the surface to be measured, and the reflectance measuring means or step irradiates light of a plurality of wavelengths. The parameter optimization means or step minimizes the reflectance unevenness of the measurement region on the measurement surface of the surface position measurement means or the phase unevenness of the reflected light from the measurement value obtained by the reflectance measurement means or step. A wavelength is selected, and in the surface position measuring means or step, the position of the surface to be measured is measured using light of the wavelength determined by the parameter optimizing means.

  In the above aspect, a wavelength tunable liquid crystal filter is used for selectively irradiating a plurality of wavelengths.

  In the above aspect, a plurality of LDs or LEDs having different wavelengths are used for selective irradiation of a plurality of wavelengths.

  In the above aspect, the numerical aperture (NA) of the optical system used for the surface position measurement is the same as or smaller than the numerical aperture of the optical system used for the reflectance measurement.

  In the above aspect, the surface position measurement and the reflectance measurement are switched by a digital mirror device (DMD) arranged on the same optical path.

  An exposure apparatus according to a second aspect of the present invention includes any one of the above-described measurement apparatuses, corrects the substrate surface to an optimum exposure image surface position based on the measurement value of the surface position measurement unit, and The original pattern is exposed on the substrate by scanning the substrate relatively.

  The exposure apparatus according to the third aspect of the present invention has surface position measuring means for measuring the position of the substrate surface, and sets the substrate surface to an optimum exposure image surface position based on the measurement value of the surface position measuring means. An exposure apparatus that corrects and relatively scans the original and the substrate to expose the original pattern on the substrate, and irradiates at least two points in the direction orthogonal to the scanning direction with light from an oblique direction. A means for detecting reflected light from the substrate, a reflectance measuring means for measuring a reflectance distribution corresponding to an irradiation area of the illumination means, and a substrate measured by the reflectance measuring means. Parameter optimization means for optimizing the measurement parameters of the surface position measurement means based on the reflectance distribution, and the surface position measurement means measures the substrate using the measurement parameters determined by the parameter optimization means. The height of the point The calculated, calculates the average height and inclination in the exposure area from the information from at least two points of measurement points.

  In the above aspect, the parameter optimization means includes means for determining an offset E based on a relationship between a predetermined reflectance distribution and a measurement offset E of the surface position measurement means, and the surface position measurement The position of the substrate surface is determined by correcting the measured value of the means with the offset E.

  Further, in the above aspect, the surface position measuring means has means for irradiating light of a plurality of wavelengths to measure the position of the substrate surface, and the reflectance measuring means irradiates light of a plurality of wavelengths. Means for measuring the reflectivity of the substrate surface, and the parameter optimizing unit is configured to determine, from the measurement value of the reflectivity measurer, the unevenness of reflectivity in the measurement region on the substrate of the surface position measurer, or the phase of the reflected light The surface position measuring means measures the position of the substrate surface using the light having the wavelength determined by the parameter optimizing means.

  Moreover, the device manufacturing method of the 4th aspect of this invention manufactures a semiconductor device using one of the said exposure apparatuses.

  According to the present invention, it is possible to realize highly accurate surface position measurement that is not affected by uneven reflectance of a measurement object such as a wafer.

  Also, according to the exposure apparatus of the present invention, high focus correction accuracy can be achieved with high throughput with respect to the reduced depth of focus, and the yield per substrate can be improved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  FIG. 3 is a view showing the arrangement of an exposure apparatus according to an embodiment of the present invention.

  The exposure apparatus of this embodiment is a projection exposure apparatus that exposes a wafer 3 with a circuit pattern formed on a reticle 1 by a step-and-scan method. Such an exposure apparatus is suitable for a lithography process of submicron or quarter micron or less. As shown in FIG. 3, the exposure apparatus includes an illumination apparatus 700, a reticle stage RS on which the reticle 1 is placed, a projection optical system 2, a wafer stage WS on which the wafer 3 is placed, and a focus / tilt measurement system 33. And an arithmetic processing unit 400, a wafer reflectance distribution measurement system 39, and an arithmetic processing unit 402.

  The control unit 1100 includes a CPU and a memory, and is electrically connected to the illumination device 800, the reticle stage RS, the wafer stage WS, and the focus / tilt measurement system 33, and controls the operation of the exposure apparatus. In this embodiment, the control unit 1100 also performs correction calculation and control of measurement values when a focus / tilt measurement system 33 (to be described later) detects the surface position of the wafer 3.

  The illumination device 700 illuminates the reticle 1 on which a transfer circuit pattern is formed, and includes a light source unit 800 and an illumination optical system 801.

  The light source unit 800 uses a laser, for example. As the laser, an ArF excimer laser with a wavelength of about 193 nm, a KrF excimer laser with a wavelength of about 248 nm, or the like can be used. However, the type of light source is not limited to the excimer laser, for example, an F2 laser with a wavelength of about 157 nm or a wavelength of 20 nm or less. EUV (Extreme Ultra Violet) light may be used.

  The illumination optical system 801 is an optical system that illuminates the surface to be illuminated using a light beam emitted from the light source unit 800. In this embodiment, the light beam is formed into an exposure slit having a predetermined shape optimum for exposure, and the reticle 1 is used. Illuminate. The illumination optical system 801 includes a lens, a mirror, an optical integrator, a diaphragm, and the like. For example, a condenser lens, a fly-eye lens, an aperture diaphragm, a condenser lens, a slit, and an imaging optical system are arranged in this order. The illumination optical system 801 can be used regardless of whether it is axial light or off-axis light. The optical integrator includes an integrator configured by stacking a fly-eye lens and two sets of cylindrical lens array (or lenticular lens) plates, but may be replaced by an optical rod or a diffractive element.

  The reticle 1 is made of, for example, quartz, on which a circuit pattern to be transferred is formed, and is supported and driven by the reticle stage RS. Diffracted light emitted from the reticle 1 passes through the projection optical system 2 and is projected onto the wafer 3. The reticle 1 and the wafer 3 are arranged in an optically conjugate relationship. The pattern of the reticle 1 is transferred onto the wafer 3 by scanning the reticle 1 and the wafer 3 at the speed ratio of the reduction magnification ratio. The exposure apparatus is provided with a light oblique incidence type reticle measurement system 36, and the position of the reticle 1 is detected by the reticle measurement system 36 and placed at a predetermined position.

  The reticle stage RS supports the reticle 1 via a reticle chuck (not shown) and is connected to a moving mechanism (not shown). The moving mechanism is configured by a linear motor or the like, and can move the reticle 1 by driving the reticle stage RS in the X-axis direction, the Y-axis direction, the Z-axis direction, and the rotation direction of each axis.

  The projection optical system 2 has a function of forming an image of a light beam from the object plane on the image plane. In this embodiment, the projection optical system 2 forms an image on the wafer 3 of diffracted light that has passed through the pattern formed on the reticle 1. The projection optical system 2 includes an optical system composed only of a plurality of lens elements, an optical system (catadioptric optical system) having a plurality of lens elements and at least one concave mirror, a plurality of lens elements, and at least one kinoform. An optical system having a diffractive optical element such as can be used. When correction of chromatic aberration is required, a plurality of lens elements made of glass materials having different dispersion values (Abbe values) can be used, or the diffractive optical element can be configured to generate dispersion in the opposite direction to the lens element. To do.

  The wafer 3 is an object to be processed, and a photoresist is applied on the substrate. In the present embodiment, the wafer 3 is also a measurement object whose position is detected by the focus / tilt measurement system 33. In another embodiment, the wafer 3 is replaced with a liquid crystal substrate or another object to be processed.

  Wafer stage WS supports wafer 3 by a wafer chuck (not shown). Similar to reticle stage RS, wafer stage WS moves wafer 3 in the X-axis direction, Y-axis direction, Z-axis direction, and the rotation direction of each axis using a linear motor. Further, the position of reticle stage RS and the position of wafer stage WS are monitored by, for example, laser interferometer 101 and the like, and both are driven at a constant speed ratio. The wafer stage WS is provided, for example, on a stage surface plate supported on a floor or the like via a damper, and the reticle stage RS and the projection optical system 2 are, for example, on a base frame placed on the floor or the like. It is provided on a lens barrel surface plate (not shown) that is supported via a damper.

  In the present embodiment, the focus / tilt measurement system 33 detects position information on the surface position (Z-axis direction) of the wafer 3 during exposure using an optical measurement system. The focus / tilt measurement system 33 makes a light beam incident on a plurality of measurement points to be measured on the wafer 3, guides each light beam to an individual sensor, and tilts a surface to be exposed from position information (measurement results) at different positions. Is detected.

  As shown in FIG. 2, the focus / tilt measurement system 33 includes an illumination unit 31 that makes a light beam incident on the surface of the wafer 3 at a high incident angle (angle θ), and an image of reflected light reflected by the surface of the wafer 3. It has the detection part 32 which detects deviation | shift, and the calculating part 400. The illumination unit 31 includes a light source S 1, a pattern plate 15, an imaging lens 16, and a mirror 17. The detection unit 32 includes a mirror 18, a lens 19, and a light receiver D1. In FIG. 2, illustrations of lenses necessary for illuminating the pattern plate 15 with a uniform illuminance distribution in the illumination unit 31 and lenses for correcting chromatic aberration in the light receiver D1 are omitted.

  Referring to FIG. 2, light having a wavelength λ1 emitted from a light source S1 such as an LED or a halogen lamp illuminates a pattern plate 15 on which a pattern such as a slit is formed. The light that has passed through the pattern plate 15 is projected and imaged on the wafer 3 via the imaging lens 16 and the mirror 17. The coherence (σ) of the illumination optical system is 1.

  Further, the light reflected by the wafer 3 is received by a light receiver D1 constituted by a light receiving element such as a CCD or a line sensor via a mirror 18 and a lens 19. Therefore, the pattern image on the surface of the wafer 3 of the pattern plate 15 is re-imaged on the light receiving element of the light receiver D1 by the lens 19.

  When the wafer 3 moves in the vertical direction (that is, the Z-axis direction) via the wafer stage WS, the pattern image of the pattern plate 15 moves in the left-right direction (that is, the X-axis direction) on the light receiver D1. Therefore, the focus / tilt measurement system 33 detects the position of the surface of the wafer 3 for each measurement point by calculating the position of the pattern image with the calculation unit 400.

  As shown in FIG. 4, the pattern plate 15 has rectangular transmission slit patterns M1, M2, and M3 formed in the light shielding portion, and the light reflected by the wafer is projected onto the lens by the transmission slit pattern being projected onto the wafer. 19, the image is re-imaged on the light receiving element of the light receiver D1.

  Next, the signal waveform detected by the light receiver D1 will be described.

  The signal waveform detected by the light receiver D1 is as shown in FIG. The intensity distributions on the light receiver D1 corresponding to the transmission slits M1, M2, and M3 in FIG. 4 are S1, S2, and S3, respectively. Since the NA (numerical aperture) of the detection unit 31 is small, the rectangular pattern is not completely resolved and has a shape like a Gaussian beam.

  When a two-dimensional sensor is used as the light receiving element, a signal waveform is obtained by integrating (or averaging) the light quantity in a direction perpendicular to the arrangement direction of the transmission slit pattern. Further, when a one-dimensional line sensor is used as the light receiving element, it is better to obtain a signal waveform by optically integrating using a cylindrical lens having power in a direction perpendicular to the arrangement direction of the transmission slit pattern. This is advantageous for improving the S / N (signal to noise ratio).

The displacement amount x of each spot on the light receiver D1 with respect to the displacement z in the Z direction of the wafer surface position is x = (2Msin θ), where M is the optical magnification of the detection unit 32 and θ is the incident angle to the wafer 3. Since it becomes * z, the displacement z of the surface position is calculated by the following simple formula.
z = x / (2Msin θ) (1)
Here, the incident angle θ is preferably 70 to 85 °, and the optical magnification M is preferably about 5 to 100 times. For example, when the incident angle is 80 degrees and the optical magnification is 30 times, the displacement z of the wafer surface position is magnified 59 times on the light receiving portion. In addition, when the pixel pitch of the light receiver D1 is 8 μm, when detecting the center of gravity position of the signal spots (S1, S2, S3) as shown in FIG. 5, it can be detected with a resolution of 1/20 pixel. In this case, the wafer surface position resolution is about 7 nm from 8/20/59 [μm], which is sufficient as the resolution for focus measurement.

  Furthermore, when resolution is required, the incident angle θ, the optical magnification M, and the pixel pitch of the light receiver D1 may be designed based on the above-described formula. In addition, the number of slits may be increased to improve the accuracy by an averaging effect.

  The barycentric positions of the signal spots S1, S2, and S3 are calculated, and the surface positions Z1, Z2, and Z3 of the wafer 3 at the slit positions are calculated by the equation (1), and the average value Zm is used as the wafer surface measurement value. To do.

  Next, focus measurement points on the wafer surface in the present embodiment will be described. FIG. 2 shows the arrangement of focus measurement points according to this embodiment.

  In the present embodiment, as shown in the figure, there are 21 measurement points in total, that is, 7 points in the scanning direction and 3 points in the direction perpendicular to the scanning direction (slit longitudinal direction) with respect to the exposure area of one shot. ing. Three focus / tilt measurement systems 33 shown in FIG. 1 are arranged side by side in the slit longitudinal direction (X) to measure three points in the slit longitudinal direction, and the wafer stage is moved in the Y direction in the scanning direction (Y). And 7 points are measured.

  Next, the wafer reflectance distribution measurement system 39 in FIG. 3 will be described in detail.

  The wafer reflectance distribution measurement system 39 is used to measure the reflectance distribution of the wafer 3 at the measurement point of the focus / tilt measurement system 33. As shown in FIG. 6, the wafer reflectance distribution measurement system 39 includes an illumination unit 37 that causes a parallel light beam to be incident on the surface of the wafer 3 at the same incident angle θ as the focus / tilt measurement system 33, and the surface of the wafer 3. And a calculation unit 402. The detection unit 38 detects the intensity distribution of the reflected light reflected by the light source. The illumination unit 37 includes a light source S2 (the same light source as the focus measurement system is used and the center wavelength, wavelength width, and polarization state are aligned with the light source S1), a collimator lens 26, and a half mirror 40. . The detection unit 38 includes a half mirror 41, a lens 29, and a light receiver D2. In FIG. 6, lenses for correcting chromatic aberration are not shown.

  Referring to FIG. 6, light having a wavelength λ1 emitted from a light source S2 such as an LED or a halogen lamp is collimated by a collimator lens and illuminates the wafer 3. Further, the light reflected by the wafer 3 is received by a light receiver D2 constituted by a light receiving element of a CCD element through a lens 29. Here, the wafer surface and the light receiver D2 have a conjugate relationship with respect to the lens 29, and the wafer surface is imaged on the light receiver D2. Further, the lens 29 has a larger numerical aperture (NA) than the imaging lens 19 used in the focus / tilt measurement system 33. When the numerical aperture of the imaging lens 19 is NA1, the numerical aperture NA2 of the lens 29 is designed to satisfy NA2> 5 * NA1. The reason is that the resolution is proportional to λ / NA when the wavelength is λ. Therefore, the NA of the reflectance distribution measurement system is made larger than the NA of the focus measurement system, so that the illumination slit of the focus / tilt measurement system 33 is increased. This is because the reflectance distribution inside can be measured with a resolution five times or more that of the focus / tilt measurement system 33.

  FIG. 7 shows an example of the wafer reflectance distribution measured by the wafer reflectance distribution measuring system 39. In the light receiver D2, an intensity distribution such as 50 is measured.

  In the figure, slit images S1 ', S2' and S3 'respectively indicate the irradiation positions on the wafer of the slit marks M1, M2 and M3 of the pattern plate 15. In which position of the light receiver D2 of the wafer reflectance distribution measurement system 39 the slit image is positioned is determined in advance by causing the light source S1 to emit light. In FIG. 7, the irradiation position of the slit images S1 'and S2' has no reflectance unevenness and the signal is not distorted, so that no measurement error occurs. On the other hand, since the slit of S3 'is irradiated to a position having a different reflectance, a measurement error occurs. When the illumination slit is irradiated to a position including a region having a different reflectance such as S3 ′, as shown in FIG. 8, the signal of the light reflected and irradiated to the region where the reflectance is constant becomes a target waveform, The light signal reflected by the regions having different reflectivities has an asymmetric waveform. Since the detection signal is a signal obtained by integrating the symmetric part and the asymmetric part, the waveform is slightly distorted in the measurement direction as a total. As a result, a measurement error occurs.

Next, the relationship between the wafer reflectance unevenness and the measurement error will be described. FIG. 8 is a schematic diagram when the slit S3 ′ is irradiated to the boundary between the reflectance R1 and the reflectance R2. When arbitrary values are input to the reflectances R1 and R2 on the wafer, and an optical simulation is performed using the light reflected by the slit S3 ′, and there is no unevenness in reflectance based on the simulation image The offset E with respect to the simulation image is estimated. Here, as contrast C of the reflectance of the wafer,
C = (R1-R2) / (R1 + R2) (2)
As a result of examination, it was found that there is a proportional relationship between the contrast C and the offset E as shown in FIG.

In response to this result, the reflectance contrast C in each slit is calculated based on the measurement result of the reflectance distribution measuring system 39, and the offset amount E can be calculated by the following equation. Here, A indicates the slope component of FIG.
E = A * c (3)
Further, as shown in FIG. 8, when there is a shift XS between the center of the slit S3 ′ and the boundary where there is a difference in wafer reflectivity (Y ′ axis in the figure), the straight line of the offset E with respect to the reflectivity contrast C shown above. The slope changes slightly.

  FIG. 10 shows a plot of the calculated value of the offset E when the shift XS is shifted by ± 200 μm, and shows how the slope changes.

That is, by using the gradient of the relational expression between the reflectance contrast C and the offset E as a function of the shift XS as in the following expression, correction with higher accuracy can be performed.
E = A (XS) * c (4)
Here, the slope function A (XS) is a quadratic function, that is, a function like the following equation, and parameters (a, b, c) are assumed, and the reflectance R1, R2 of the wafer and the shift XS are assumed. And determined by optical simulation.
A (XS) = aXS ² + bXS + c (5)
After introducing the reflectance distribution measured by the reflectance distribution measuring system 39 into the equation (2) to calculate the reflectance contrast C and obtaining the shift XS, the coefficients are determined in advance (4), (5 By substituting this (C, XS) into the formula, the offset amount E is instantaneously calculated.

  In the present embodiment, an example is shown in which correction is performed using a functional equation. However, a method may be used in which a correction table for the contrast C and XS obtained from the reflectances R1 and R2 is input to the apparatus in advance. Furthermore, in addition to the method of calculating the relationship between the wafer reflectance distribution and the offset by optical simulation, the wafer reflectance distribution measurement system 39 measures the wafer reflectance distribution on the wafer at the head of the lot, and no correction is performed. The relationship between the reflectance distribution and the offset amount E may be obtained by performing an exposure operation after controlling the Z / tilt of the wafer using the surface position detection system 33 and inspecting the focus accuracy. In this case, the conversion formula or conversion table for the reflectance distribution obtained from the preceding wafer is registered in the exposure apparatus, and the conversion formula (or conversion table) is calculated from the reflectance distribution measurement value for the next wafer. By correcting the surface position measurement result with the offset E based on the above, the wafer surface position can be accurately measured.

Finally, the points of the present invention will be organized again using FIG. In step 1, the relational expression between the contrast C of the wafer reflectivity R1 and R2 and the offset amount E is compared with the optical simulation or the exposure result in advance according to the irradiation pattern on the wafer of the focus / tilt measurement system 33 of the exposure apparatus. And is registered in the exposure apparatus. Subsequently, the wafer is mounted on the exposure apparatus, and the wafer reflectance distribution measurement system 39 is used in Step 2 to measure the reflectance distribution of the wafer, thereby obtaining the reflectance contrast C and the shift XS from the reflectance boundary. Subsequently, in step 3, the surface position Zm of the wafer is measured using the focus / tilt measurement system 33. In Step 4, the offset amount E is calculated from the reflectance contrast C and the shift XS. After the surface position measurement value is corrected using the offset amount E in Step 5, the wafer Z and tilt are corrected in Step 6.
[Second Embodiment]
Next, a second embodiment will be described.

  FIG. 12 is a diagram showing a focus / tilt measurement system and a wafer reflectance distribution measurement system used in this embodiment. Since other configurations and functions are the same as those of the first embodiment, detailed description thereof is omitted. In the present embodiment, unlike the first embodiment, the focus / tilt measurement system and the wafer reflectance distribution measurement system are integrated. In FIG. 12A, S3 is a light source, which is a broadband light source having a wavelength width of 400 to 700 nm, and a combination of a halogen lamp and LEDs having a plurality of wavelengths is used. Reference numeral 63 denotes a wavelength selection element, for which a liquid crystal filter or the like is used. The light transmitted through the wavelength selection element is reflected by a DMD (digital mirror device) 64, and the light reflected by the DMD 64 is irradiated onto the wafer 3 through lenses 65 and 65. The reflected light of the wafer 3 is received by a light receiver D3 comprising a CCD via lenses 67 and 68. The DMD 64 has a conjugate relationship with the wafer 3 with respect to the lenses 65 and 66, and the light receiver D3 has a conjugate relationship with the wafer 3 and the lenses 67 and 68. The DMD 64, the wafer 3 and the light receiver D3 are shine. Satisfied the proof relationship.

The DMD 64 is a device in which mirrors of about 16 μm ² are arranged in an array on a CMOS substrate, and the angle changes by ± 12 degrees depending on whether the CMOS memory is turned on or off. When the memory is ON, it is arranged so as to pass through the center of the optical axis of the illumination optical system. Since the NA (numerical aperture) of the illumination system is 10 degrees or less in angle, the light reflected by the DMD 64 in the area where the memory is OFF passes outside the NA of the illumination optical system, and illumination optics. The system is configured to be blocked by a diaphragm (not shown) of the system and not reach the wafer.

  In this embodiment, at the time of measuring the reflectance distribution, as shown in FIG. 12B, all the memory cells of the DMD 64 are turned on to uniformly illuminate the wafer. On the other hand, at the time of focus / tilt measurement, the DMD 64 is controlled so that an irradiation slit is generated on the wafer 3 as shown in FIG. Since the switching speed of the DMD 64 is as fast as 0.2 msec or less, it is possible to switch between focus measurement and reflectance distribution measurement even during exposure apparatus scanning.

  Now, the wavelength selection element 63 which is another point of the present embodiment will be described in detail. The wavelength selection element is an element that transmits only a spectrum having a predetermined wavelength out of light from a light source having a wide wavelength width. FIG. 13 shows an example of the transmission spectrum of this element, which transmits a full width at half maximum of about 20 nm.

  Next, the correction method of this embodiment using this wavelength selection element will be described.

First, in the shot layout of the wafer 3, one or a plurality of shots are selected (referred to as sample shots), and the wafer reflectivity distribution of the sample shot is measured by the wafer reflectivity distribution measurement system. The reflectance distribution is measured while switching the transmission wavelength of the wavelength selection element at this time. When a plurality of sample shots are selected, an average value of measurement values is obtained for each measurement point in the shot. Subsequently, the contrast of the reflectance is calculated based on the equation (2) using the measured value of the reflectance distribution. The reflectance contrast Csij (λ) is calculated for all wavelengths of light and all measurement points. Here, the subscript s is the sample shot number, i is the in-shot measurement position number in the slit longitudinal direction, j is the in-shot measurement position number in the scanning direction, and λ is the wavelength of the illumination light. FIG. 11 shows measurement points in the shot. In the present embodiment, as shown in FIG. 11, a total of 21 measurement points, that is, 7 points in the scanning direction and 3 points in the direction perpendicular to the scanning direction (slit longitudinal direction) are obtained for one exposure area 51. Have. Three focus / tilt measurement systems 33 are arranged in the slit longitudinal direction (X-axis direction) to measure three measurement points in the slit longitudinal direction, and the wafer stage WS is scanned in the Y-axis direction to scan direction (Y (Axial direction) 7 measurement points can be measured. Further, in order to expose a plurality of shots on the wafer 3, the wafer stage WS is stepped or scanned for each shot, and measurement is performed on the 21 measurement points shown in FIG. As the measurement points in the slit longitudinal direction, it is necessary to obtain the tilt amount ωy of the wafer 3 in the slit longitudinal direction at least, so two or more measurement points are required. Further, when it is necessary to measure the tilt amount ωx of the wafer 3 in the scan direction in the slit, measurement points at different positions in the scan direction in the exposure slit 50 and a focus / tilt measurement system 33 corresponding to the position are provided. Next, based on the signal contrast Csij (λ), the average of the reflectance contrast of all the sample shots is obtained, and the wavelength at which the reflectance contrast at the measurement position (i, j) in the shot is minimized Let λ be the optimum wavelength λopt (i, j) of each measurement position (i, j) in the shot. As shown in FIG. 10 of the previous embodiment, the smaller the reflectance contrast C, the smaller the offset E (measurement error). Therefore, it can be said that the measurement accuracy is good because the influence of signal waveform distortion is reduced. Therefore, a wavelength that minimizes the contrast of the reflectance may be selected. Here, the same effect can be obtained by selecting a wavelength that minimizes the phase unevenness of the reflected light in the measurement region of the focus / tilt measurement system 33 instead of the reflectance. The method for measuring the phase of the reflected light will be described in detail in a later embodiment.

  After selecting the optimum wavelength λopt (i, j), the DMD 64 is switched for focus detection and illuminated with the optimum wavelength λopt (i, j). From the signal waveform, the position X1, X2, position of the slit pattern image X3 is measured, the surface position of the wafer 3 is calculated based on the equation (1), and the average value Zm is obtained.

  Finally, the exposure sequence of this embodiment will be described in detail. FIG. 14 is a flowchart for explaining an exposure method using the exposure apparatus. Referring to FIG. 14, first, the wafer 3 is carried into the exposure apparatus (step S1002), and it is determined whether or not the focus / tilt measurement system optimizes the wavelength of light that illuminates the measurement point (step S1003). . Whether or not to optimize the wavelength is registered in advance in the exposure apparatus.

  If wavelength optimization is required, the reflectance measurement system measures the wafer's reflectance distribution for all light wavelengths that can be used by the focus / tilt measurement system in the sample shot (step S1004), the surface reflectance information is stored (step S1005). Then, it is determined whether or not there is an unmeasured sample shot (unmeasured sample shot) (step S1006). If there is an unmeasured sample shot, measurement of the reflectance distribution of the unmeasured shot and reflectance distribution are performed. Information storage is repeated until there are no unmeasured sample shots.

  When measurement of the reflectance distribution of the sample shot and storage of the reflectance distribution information are completed (that is, when there is no unmeasured sample shot), measurement within the shot is performed based on the reflectance information of each sample shot stored in step S1007. The optimum wavelength λopt (i, j) is calculated for each point (step S1010).

  On the other hand, if it is not necessary to optimize the wavelength, the focus / tilt measurement system determines whether or not the optimum wavelength of light for illuminating the measurement point has been calculated (step S1008). Here, for example, the determination is made based on whether or not the optimum wavelength λopt (i, j) is calculated by the preceding wafer. If the optimum wavelength λopt (i, j) has been calculated, the process proceeds to step S1010. If the optimum wavelength λopt (i, j) has not been calculated, the same default wavelength is selected for all measurement points (step S1009), and the process proceeds to step S1010.

  In step S1010, the wavelength of the light that illuminates the measurement point by the focus / tilt measurement system is set to the optimum wavelength λopt (i, j) or the default wavelength. Thereafter, the wafer stage WS is driven to set the exposure shot at the exposure position (step S1011), and the exposure shot is focused / tilted using the optimum wavelength λopt (i, j) or the default wavelength light. The surface position is measured (step S1012).

Next, based on the surface position measured in step S1012, the wafer 3 is driven to correct focus and tilt (step S1013), and the pattern on the reticle 1 is exposed on the wafer 3 (step S1014). Then, it is determined whether or not there is a shot to be exposed (that is, an unexposed shot) (step S1015), and step S1011 and subsequent steps are repeated until there is no unexposed shot. When exposure of all exposure shots is completed, the wafer 3 is collected (step S1016), and the process ends. In addition, in each step of the sequence shown here, it is preferable that the steps that can be processed in parallel are processed in parallel in consideration of throughput.
[Third Embodiment]
Next, a third embodiment will be described. This embodiment shows an example of an embodiment in which the wafer reflectance distribution measurement system is different from that of the first embodiment. In the first embodiment, the reflectance (intensity) distribution of the wafer is measured. In the present embodiment, the wafer reflection is performed by an interference method in order to measure the distribution of phase information in addition to the intensity (amplitude). It is characterized by configuring a rate distribution measurement system.

  FIG. 15 shows the relationship between the optical axis of the focus / tilt measurement system 33 (the configuration is the same as that of the first embodiment and the description thereof will be omitted) and the optical axis of the wafer reflectance distribution measurement system 80 used in this embodiment. Is shown. The focus / tilt measurement system 33 illuminates and detects the illumination slit image 72 tilted from the XY axis so that the irradiation slit image 72 tilts from the XY axis. The wafer reflectance distribution measurement system 80 has an optical axis on the X axis. Has been placed.

  As shown in FIG. 16, in the wafer reflectance distribution measurement system 80, the light emitted from the coherent light source 73 is divided into two by the half mirror 74, the transmitted light is incident on the wafer 3, and the reflected light from the half mirror 74 is a reference. Incident on the mirror 75. The light source S3 uses a wavelength that matches the center wavelength of the light source S1 of the focus / tilt measurement system 33. The lights reflected by the wafer 3 and the reference mirror 75 are combined by the half mirror 76, and the combined light is received by the CCD camera 77 to obtain interference fringes. In FIG. 16, a collimator lens for adjusting the light beam to parallel light and an imaging lens are omitted.

  Next, a method for measuring the wafer reflectance distribution using the wafer reflectance distribution measuring system 80 will be described. As methods for analyzing interference fringes obtained by an interferometer (calculation of amplitude and phase distribution), there are a fringe scanning method (fringe scanning method) and a Fourier transform method as known techniques. Here, the amplitude / phase calculation method is shown by taking the fringe scan method as an example. In the fringe scanning method, the reference plane or the test surface is moved slightly in the optical axis direction, the distance between the two is changed, and the interference fringes are changed (also called scanning).

The reference mirror 75 is changed in the Z direction by an actuator (not shown) at a pitch at which the interference fringes are scanned by π / 2 within a range in which the interference fringes are scanned by exactly one cycle (2π), and the interference fringes are π / 2 during that time. Each time it is scanned, it captures the image four times (called the four-step method) and calculates the phase. If the intensity of each measurement time at the measurement point is I1, I2, I3, I4, the initial phase (φ) is
φ = tan ⁻¹ {(I4-I2) / (I1-I3)} (6)
Can be obtained from

The reflection intensity I is
I = (I1 + I3) / 2 (7)
It is.

  In this way, the phase distribution and intensity distribution in the irradiation slit 72 of the focus / tilt measurement system 33 are calculated.

  In this embodiment, based on the measured reflectance distribution (intensity, phase), an optical image detected by the focus / tilt measurement system 33 is calculated by an optical simulation each time, and an offset amount E is calculated. The measurement value Zm of the focus / tilt measurement system 33 is corrected.

  Further, as shown in FIG. 17, the configuration of the exposure apparatus in the present embodiment is a configuration called a twin stage, which is separated into an exposure station and a measurement station. The focus / tilt measurement system 33 and the wafer reflection are arranged in the measurement station. A rate distribution measurement system 80 is arranged. The wafer is first loaded into the measurement station, and the measurement of the surface shape of the wafer 3, the measurement of the reflectance distribution, and the calculation of the offset amount E based on the calculation of the optical simulation are performed at the measurement station. While the chuck 84 is fed, the offset amount E is corrected, and an accurate measurement value of the surface shape of the wafer 3 is obtained. Reference mark stands 80, 81 and 82 (not shown) integrated with the wafer chuck are also measured by the focus / tilt measurement system 33, and the wafer surface shape data is obtained as a difference from the plane formed by the reference mark stand. Stored in In the measurement station, the in-plane positional deviation of the wafer is also measured by an alignment scope (not shown). Alignment marks are formed on fiducial mark stands 80, 81, and 82 (not shown), and the surface of the wafer relative to the fiducial mark stand is measured by measuring the position of the alignment mark on the fiducial mark stand with an alignment scope. The internal position shift is stored in the exposure apparatus.

  As indicated by the arrow in FIG. 17, the position in the Z direction is measured by the second focus detection system 85 in which the reference mark base integrated with the wafer chuck 84 is sent to the exposure station and attached to the exposure station side. In the exposure station, positioning in the Z direction is performed. Since the reference mark stands 80, 81, and 82 do not have a reflectance distribution that causes a measurement offset in the focus detection system 85, accurate measurement in the Z direction is possible. Further, the in-plane position is determined by measuring and positioning the position of the alignment mark on the reference mark bases 80, 81, 82. During the scanning exposure of the pattern on the reticle 1, the wafer is measured by a measurement station so that the surface of the wafer 3 is positioned on the optimum image plane of the projection lens 2 based on the wafer surface shape stored in the exposure apparatus. Z / tilt control is performed.

  Further, the wafer is aligned with the exposure apparatus based on the in-plane position information of the wafer stored in the exposure apparatus.

  In this embodiment, the reflectance distribution measurement of all wafers may be performed, and a correction value (offset E) is obtained from the reflectance distribution measurement of the wafer at the head of the lot, and the correction value is used for the subsequent wafers. You may make it do. Further, instead of measuring all the shots to be exposed, as described in the second embodiment, several sample shots are selected, the reflectance distribution of the sample shots is measured, and the offset amount E is measured. An average value may be obtained for each measurement point in the shot between the sample shots, and the offset amount may be used for correcting the measurement value of each shot.

  As in the present embodiment, by measuring not only the intensity of the reflectance distribution of the wafer but also the distribution of the phase information, it is possible to obtain a special effect that more accurate correction accuracy can be obtained.

Although the present invention has been described using a plurality of embodiments, in the present invention, it can be easily understood by those skilled in the art that the same effect can be obtained by combining the elements of each embodiment. The explanation is omitted.
[Device manufacturing method]
Next, a semiconductor device manufacturing process using the exposure apparatus of this embodiment will be described. FIG. 19 is a diagram showing a flow of an entire manufacturing process of a semiconductor device. In step S1 (circuit design), a semiconductor device circuit is designed. In step S2 (mask fabrication), a mask is fabricated based on the designed circuit pattern.

  On the other hand, in step S3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step S4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer using the above-described mask and wafer using the above-described exposure apparatus by utilizing lithography technology. The next step S5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step S5. The assembly process (dicing, bonding), packaging process (chip encapsulation), etc. Process. In step S6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step S5 are performed. A semiconductor device is completed through these steps, and is shipped in step S7.

  The wafer process in step S4 has the following steps (FIG. 20). An oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, an electrode formation step for forming electrodes on the wafer by vapor deposition, an ion implantation step for implanting ions on the wafer, and applying a photosensitive agent to the wafer A resist processing step, an exposure step for transferring the circuit pattern to the wafer after the resist processing step by the above exposure apparatus, a development step for developing the wafer exposed in the exposure step, and an etching step for scraping off portions other than the resist image developed in the development step A resist stripping step that removes the resist that has become unnecessary after etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

It is a block diagram explaining the concept of this invention. It is a figure explaining the structure of the focus measurement system which is 1st Embodiment based on this invention. It is a figure explaining the exposure apparatus which is embodiment which concerns on this invention. It is a figure explaining the focus measurement mark used in the 1st embodiment concerning the present invention. It is a figure explaining the focus signal which is the 1st embodiment concerning the present invention. It is a figure which shows the structure of the wafer reflectance distribution measurement system of 1st Embodiment which concerns on this invention. It is a figure which shows the relationship between the measurement result of the wafer reflectance distribution measurement system of 1st Embodiment which concerns on this invention, and the measurement point of a focus measurement system. It is a figure which shows the definition of the contrast of the wafer reflectance of 1st Embodiment which concerns on this invention. It is a figure which shows the relationship between a reflectance contrast and the offset amount of a surface position measured value. It is a figure which shows the relationship between the reflectance contrast and the offset amount of the surface position measurement value with respect to a surface position measurement position. It is a figure which shows an example of the measurement point in the shot of a surface position detection system. It is a figure which shows the structure of the wafer reflectance distribution measurement system and surface position detection system of 2nd Embodiment which concerns on this invention. It is a figure which shows the transmitted light spectrum of the wavelength selection element of 2nd Embodiment which concerns on this invention. It is a figure explaining the exposure sequence of 2nd Embodiment which concerns on this invention. It is a figure which shows arrangement | positioning of the surface position detection system and wafer reflectance distribution measurement system of 3rd Embodiment based on this invention. It is a figure which shows the structure of the wafer reflectance distribution measurement system of 3rd Embodiment which concerns on this invention. It is a figure which shows the structure of the exposure apparatus of 3rd Embodiment which concerns on this invention. It is a figure which shows the signal correction method in the case of the conventional reflectance nonuniformity. It is a figure explaining the manufacturing flow of a microdevice. It is a figure explaining a wafer process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reticle 2 Projection lens 3 Wafer S1, S2, S3 Light source 17, 18 Mirror 15 Pattern board 16, 19, 26, 29, 62, 65-68 Lens D1, D2, D3 Light receiver 23 Optical demultiplexing means 24 Signal processing calculation Instrument 31 Illumination system for focus / tilt measurement system 32 Detection system for focus / tilt measurement system 33 Focus / tilt measurement system 34 Illumination system for reticle focus / tilt measurement system 35 Detection system for reticle focus / tilt measurement system 36 Reticle focus / tilt Measurement system 37 Wafer reflectance distribution measurement system illumination system 38 Wafer reflectance distribution measurement system detection system 39 Wafer reflectance distribution measurement system 40, 41, 74, 76 Half mirror 50 Exposure slit 51 Exposure shot area 63 Wavelength selection element 64 Digital Mirror device 73 Coherent light source 75 Mirror 77 CCD camera 0-82 Reference mark stand 84 Wafer chuck 85 Focus detection system 101 Interferometer 400 Focus signal processing system 401 Reticle focus signal processing system 402 Wafer reflectivity processing system 800 Exposure laser light source 801 Projection exposure illumination optical system 1000 Stage drive system 1100 Control system RS Reticle stage WS Wafer stage WS1 Wafer stage for exposure station WS2 Wafer stage for measurement station

Claims (17)

Surface position measuring means for measuring the position of the surface to be measured;
A reflectance measuring means for measuring the reflectance of the surface to be measured;
Parameter optimization means for optimizing the measurement parameters of the surface position measuring means based on the reflectance distribution of the surface to be measured measured by the reflectance measuring means,
The surface position measuring means measures the position of the surface to be measured using the optimized measurement parameter. The parameter optimization means includes means for determining an offset based on a relationship between a predetermined reflectance distribution and a measurement offset of the surface position measurement means,
The measurement apparatus according to claim 1, wherein the measurement surface position is determined by correcting the measurement value of the surface position measurement unit with the offset. The surface position measuring unit includes a first illumination unit that irradiates a surface to be measured with a slit-shaped pattern, and a detecting unit that receives reflected light from the surface to be measured.
The measuring apparatus according to claim 2, wherein the reflectance measuring unit includes a second illuminating unit having the same wavelength, incident angle, and polarization state as the first illuminating unit.   The reflectance measuring means receives reflected light from the surface to be measured, measures the reflectance distribution and the phase distribution, and uses the reflectance distribution and the phase distribution to calculate the measurement offset of the surface position measuring means. The measuring apparatus according to claim 1, wherein the measuring apparatus is characterized.   The measurement apparatus according to claim 1, wherein an optical simulation based on a measurement value of the reflectance measurement unit is used for calculating the offset.   5. The measuring apparatus according to claim 1, wherein a measurement value and an exposure result of the reflectance measuring unit are used for the calculation of the offset. The surface position measuring means has means for irradiating light of a plurality of wavelengths to detect the position of the surface to be measured,
The reflectance measuring means has means for irradiating light of a plurality of wavelengths,
The parameter optimizing unit is a unit that selects, from the measurement value of the reflectance measuring unit, a wavelength that minimizes the reflectance unevenness of the measurement region on the measurement target surface of the surface position measuring unit or the phase unevenness of the reflected light. Have
The measurement apparatus according to claim 1, wherein the surface position measurement unit measures the position of the surface to be measured using light having a wavelength determined by the parameter optimization unit.   8. The measuring apparatus according to claim 7, wherein a tunable liquid crystal filter is used as means for selectively irradiating a plurality of wavelengths.   The measuring apparatus according to claim 7, wherein a plurality of LDs or LEDs having different wavelengths are used as means for selectively irradiating a plurality of wavelengths.   The measurement apparatus according to claim 1, wherein the numerical aperture of the surface position measurement unit is the same as or smaller than the numerical aperture of the reflectance measurement unit.   2. The measuring apparatus according to claim 1, wherein switching between the surface position measuring unit and the reflectance measuring unit is performed by a digital mirror device arranged on the same optical path.   A measurement apparatus according to any one of claims 1 to 11 is mounted, the substrate surface is corrected to an optimum exposure image surface position based on the measurement value of the surface position measurement means, and the original and the substrate are relatively relative to each other. An exposure apparatus for exposing the original pattern on the substrate by scanning. A surface position measuring means for measuring the position of the substrate surface, correcting the substrate surface to an optimum exposure image surface position based on the measurement value of the surface position measuring means, and relatively scanning the original and the substrate; An exposure apparatus that exposes an original pattern on a substrate,
Illuminating means for irradiating light from an oblique direction to an area of at least two points in the direction orthogonal to the scanning direction;
Detecting means for detecting reflected light from the substrate;
Reflectivity measurement means for measuring the reflectance distribution corresponding to the irradiation area of the illumination means;
Based on the reflectance distribution of the substrate measured by the reflectance measuring means, the parameter optimization means for optimizing the measurement parameters of the surface position measuring means,
The surface position measuring means obtains the position in the height direction of the measurement point on the substrate using the measurement parameter determined by the parameter optimization means, and averages the exposure area from information from at least two measurement points. An exposure apparatus that calculates height and inclination. The parameter optimization means includes means for determining an offset E based on a relationship between a predetermined reflectance distribution and a measurement offset E of the surface position measurement means,
14. The exposure apparatus according to claim 13, wherein the position of the substrate surface is determined by correcting the measurement value of the surface position measuring means with the offset E. The surface position measuring means has means for measuring the position of the substrate surface by irradiating light of a plurality of wavelengths,
The reflectance measuring means has means for irradiating light of a plurality of wavelengths and measuring the reflectance of the substrate surface,
The parameter optimizing means has means for selecting, from the measurement values of the reflectance measuring means, a wavelength that minimizes the reflectance unevenness of the measurement region on the substrate of the surface position measuring means or the phase unevenness of the reflected light. ,
15. The exposure apparatus according to claim 14, wherein the surface position measurement unit measures the position of the substrate surface using light having a wavelength determined by the parameter optimization unit.   16. A device manufacturing method, wherein a semiconductor device is manufactured using the exposure apparatus according to any one of claims 12 to 15. A surface position measuring process for measuring the position of the surface to be measured;
A reflectance measurement process for measuring the reflectance of the surface to be measured;
A parameter optimization step of optimizing measurement parameters in the surface position measurement step based on the reflectance distribution of the measurement target surface measured in the reflectance measurement step;
In the surface position measuring step, the position of the surface to be measured is measured using the optimized measurement parameter.

Images