JP6406492B2 - Evaluation method, evaluation apparatus, and exposure system - Google Patents

Description

  The present invention relates to an evaluation technique for evaluating a processing condition of a pattern formed on a substrate, an exposure technique using the evaluation technique, and a device manufacturing technique using the evaluation technique.

In a lithography process for manufacturing a device (semiconductor device, etc.), a photosensitive resin (so-called resist) is applied to a substrate such as a semiconductor wafer (hereinafter simply referred to as a wafer) by a coater / developer, and the substrate is exposed. The mask pattern image is exposed by the apparatus, and the exposed substrate is developed and etched.
In addition, in order to increase the yield of devices to be finally manufactured, film thickness conditions (such as a set value of the applied film thickness) in the coater / developer, exposure conditions in the exposure apparatus, and / or etching time in the etching apparatus, etc. It is necessary to manage the machining conditions in a desired state with high accuracy. Exposure conditions in the exposure apparatus include an exposure amount (so-called dose), a focus position (a defocus amount of the substrate to be exposed with respect to the image plane of the projection optical system), and the like. In order to manage these processing conditions with high accuracy, it is necessary to evaluate those processing conditions with high accuracy.

  For example, as a conventional method for evaluating the focus position in the exposure conditions of an exposure apparatus, a pattern for mask evaluation is illuminated with illumination light whose chief ray is inclined, and the pattern image is changed while changing the height of the substrate on the stage. Is sequentially exposed to a plurality of shots on the substrate, the lateral shift amount of the resist pattern obtained by development after exposure is measured, and the focus position at the time of exposure of each shot is evaluated from the measurement result. (For example, refer to Patent Document 1).

US Patent Application Publication No. 2002/0100012

In order to further increase the yield of devices manufactured through the lithography process, it is desirable to evaluate the processing conditions such as the exposure conditions with higher accuracy and correct the processing conditions based on the evaluation result. Furthermore, in order to manufacture a device with high throughput (productivity), it is necessary to evaluate the processing conditions efficiently.
An aspect of the present invention has been made in view of such problems, and uses a substrate on which a pattern is formed to efficiently and precisely evaluate processing conditions when the pattern is formed. With the goal.

  According to the first aspect of the present invention, in the evaluation method for evaluating the processing conditions of the evaluation target pattern formed under the predetermined processing conditions, the surface of the evaluation target substrate on which the evaluation target pattern is formed is polarized on the surface. Irradiating light, receiving the diffracted light emitted from the surface by irradiation of the polarized light, detecting an amount defining the polarization state of the received diffracted light, and detecting the detected diffracted light There is provided an evaluation method including evaluating the processing conditions when the pattern to be evaluated is formed based on an amount defining the polarization state.

According to the second aspect, forming a pattern on the surface of the substrate, using the evaluation method of the aspect of the present invention, evaluating the processing conditions when the pattern is formed, and evaluating the evaluation method A semiconductor device manufacturing method including correcting a processing condition when forming a pattern according to a result is provided.
According to the third aspect, in the evaluation apparatus for evaluating the processing conditions of the evaluation target pattern formed under the predetermined processing conditions, the surface of the evaluation target substrate on which the evaluation target pattern is formed is irradiated with light. An illumination unit, a detection unit that detects light emitted from the surface by irradiation of the light from the illumination unit, and the evaluation target pattern when the evaluation target pattern is formed based on the state of the light detected by the detection unit An evaluation unit that evaluates the processing conditions, the illumination unit irradiates the surface with polarized light, the detection unit receives diffracted light emitted from the surface irradiated with the polarized light, The amount that defines the polarization state of the diffracted light is detected, and the evaluation unit forms the evaluation target pattern based on the amount that defines the polarization state of the diffracted light detected by the detection unit. Evaluate the processing conditions Valence device is provided.
In the first and third aspects, diffracted light other than the 0th-order light emitted from the surface may be detected.
Further, in the first aspect, the processing conditions may include a first processing condition and a second processing condition, and detecting the amount defining the polarization state of the diffracted light may be applied to the surface. The polarization of the diffracted light under the first evaluation condition and the second evaluation condition, which are different from each other in the incident angle of the polarized light, the wavelength of the polarized light, and the order of the diffracted light emitted from the surface. Detecting an amount that defines the state, and evaluating the processing condition when the pattern to be evaluated is formed is the polarization of the diffracted light detected under the first evaluation condition. The first processing condition is evaluated based on the amount that defines the state, and the second processing condition is evaluated based on the amount that defines the polarization state of the diffracted light detected under the second evaluation condition. Can include That.
Moreover, in the third aspect, the processing conditions may include a first processing condition and a second processing condition, and the detection unit includes an incident angle of the polarized light irradiated on the surface, and a wavelength of the polarized light. And an amount defining the polarization state of the diffracted light may be detected under a first device condition and a second device condition in which at least one condition of the order of the diffracted light emitted from the surface is different from each other, The evaluation unit evaluates the first processing condition based on the amount that defines the polarization state of the diffracted light detected by the detection unit under the first device condition, and the second device condition The second processing condition may be evaluated based on the amount that defines the polarization state of the diffracted light detected by the detector.

  According to a fourth aspect, there is provided an exposure system comprising a processing apparatus for forming a pattern on the surface of a substrate and the evaluation apparatus according to the aspect of the present invention, and adjusting the processing apparatus according to an evaluation result of the evaluation apparatus. Provided.

  According to the aspect of the present invention, it is possible to evaluate the processing conditions when the evaluation target pattern is formed with high accuracy and efficiency using the evaluation target substrate on which the evaluation target pattern is formed.

(A) is a figure which shows schematic structure of the evaluation apparatus which concerns on 1st Embodiment, (b) is a figure which shows the device manufacturing system which concerns on 1st Embodiment. (A) is a plan view showing the wafer in FIG. 1 (a), (b) is an enlarged view showing a part of the repetitive pattern in FIG. 2 (a), and (c) and (d) are repetitive pattern formations, respectively. It is an enlarged view which shows the image of the 1st and 2nd mask pattern for use. (A) is an enlarged perspective view showing a part of a repetitive pattern, (b) is a view showing the relationship between the polarization direction of incident light and the periodic direction (repetitive direction) of the repetitive pattern, and (c) is an enlarged view showing a hole pattern. It is sectional drawing. (A) is a figure which shows an example of the relationship between exposure amount and the change of a polarization state, (b) is a figure which shows an example of the relationship between a focus position and the change of a polarization state. It is a flowchart which shows an example of the method (condition extraction) which calculates | requires apparatus conditions (evaluation conditions). It is a flowchart which shows an example of the evaluation method of exposure conditions. (A) is a plan view showing an example of a shot arrangement of a conditioned wafer, (b) is an enlarged view showing one shot, and (c) is an enlarged view showing an example of an arrangement of a plurality of setting areas in the shot. . (A) and (b) are diagrams showing an example of the relationship between the exposure amount and the focus position and the Stokes parameter under the first apparatus condition, respectively, and (c) is used for obtaining the exposure amount from the Stokes parameter. It is a figure which shows an example of the curve performed. (A) and (b) are diagrams showing an example of the relationship between the exposure condition and the focus position and the Stokes parameter under the second apparatus condition, respectively, and (c) is used for obtaining the focus position from the Stokes parameter. It is a figure which shows an example of the curve performed. (A) And (b) is a figure which shows the distribution which converted and expressed the Stokes parameter S1 detected on the mutually different apparatus conditions into a brightness | luminance. (A) And (b) is a figure which shows the distribution which each converted and expressed the Stokes parameters S2 and S3 detected on the basis of a certain apparatus condition. (A) is an enlarged sectional view showing the principal part of the wafer in the second embodiment, (b) is an enlarged sectional view showing the principal part of the wafer in the next process, and (c) is a subsequent process of FIG. FIG. 4D is an enlarged sectional view showing a wafer, FIG. 4D is an enlarged sectional view showing a part of a pattern formed on the wafer, FIG. 5E is a diagram showing an example of a relationship between a spacer deposition amount and a Stokes parameter, and FIG. It is a figure which shows an example of the relationship between quantity and a Stokes parameter. It is a flowchart which shows a semiconductor device manufacturing method.

[First Embodiment]
A preferred first embodiment of the present invention will be described below with reference to FIGS. 1 (a) to 10 (b). FIG. 1A shows an evaluation apparatus 1 according to this embodiment, and FIG. 1B shows a device manufacturing system DMS according to this embodiment. In FIG. 1B, a device manufacturing system DMS includes a thin film forming apparatus (not shown) for forming a thin film on a surface (hereinafter referred to as a wafer surface) of a wafer (semiconductor wafer) as a substrate, and a resist as a photosensitive resin. A coater / developer 200 for coating and developing the wafer surface, an exposure apparatus 100 for exposing an image of a circuit pattern such as a semiconductor device on the wafer surface coated with the resist, and etching the wafer using the developed resist pattern as a mask. An etching apparatus 300 and an evaluation apparatus 1 that evaluates the processing conditions of this pattern using a pattern formed on the wafer surface after exposure and development (or after etching or the like) are provided. Further, the device manufacturing system DMS is a host computer that performs overall control of the evaluation apparatus 1, exposure apparatus 100, coater / developer 200, etching apparatus 300, etc., process management, and mediation of various information between these apparatuses. 600 and a transfer system 500 for transferring a wafer between the evaluation apparatus 1 to the etching apparatus 300 and the like.

  As the exposure apparatus 100, for example, an immersion scanning stepper (scanning projection exposure apparatus) disclosed in, for example, US Patent Application Publication No. 2007/242247 is used. Processing conditions that can be evaluated by the evaluation apparatus 1 include film thickness conditions (such as set values of film thickness) in the thin film forming apparatus and coater / developer 200, exposure conditions described later in the exposure apparatus 100, and etching conditions in the etching apparatus 300 ( Etching time etc.).

  In FIG. 1A, the evaluation apparatus 1 includes a stage 5 that supports a substantially disk-shaped wafer 10, and the wafer 10 transferred by a transfer system (not shown) is an upper surface (mounting surface) of the stage 5. And fixed and held by, for example, vacuum suction. Hereinafter, in a plane parallel to the upper surface of the stage 5 in an untilted state, the axis along the direction parallel to the paper surface of FIG. 1A is the XE axis, and the direction perpendicular to the paper surface of FIG. The axis along the direction perpendicular to the plane including the XE axis and the YE axis will be described as the ZE axis. The stage 5 passes through a first drive unit (not shown) that controls the rotation angle φ1 with the normal CA at the center of the upper surface of the stage 5 as a rotation axis, and the center of the upper surface of the stage 5, for example, and passes through the center of FIG. A second drive unit (not shown) for controlling a tilt angle φ2 (tilt angle of the wafer 10), which is an inclination angle with an axis TA (tilt axis) perpendicular to the paper surface (parallel to the YE axis) as a rotation axis. Via a base member (not shown).

  The evaluation apparatus 1 further includes an illumination system 20 that irradiates illumination light ILI as parallel light onto the surface (wafer surface) of the wafer 10 that is supported by the stage 5 and has a predetermined repetitive pattern formed on the surface, and the illumination light ILI. A light receiving system 30 that collects light (diffracted light, etc.) emitted from the wafer surface upon irradiation, an imaging device 35 that receives the light collected by the light receiving system 30 and images the wafer surface, and an imaging device An image processing unit 40 that processes the image signal output from 35 to obtain an amount (details will be described later) that defines the polarization state of the light that forms the image, and defines the polarization state thus obtained. And an arithmetic unit 50 that evaluates the above-described processing conditions using quantity information. The imaging device 35 includes an imaging optical system 35a that forms an image on the wafer surface, and a two-dimensional imaging device 35b such as a CCD or a CMOS. The imaging device 35b is, for example, the entire surface of the wafer surface of the wafer 10. The image is picked up collectively and an image signal is output. Note that the image pickup device 35b does not have to pick up an image of the entire surface of the wafer at once, and picks up an image of the surface including all the areas where the pattern is formed on the wafer surface and outputs an image signal. May be. Further, when the test pattern is formed only on a partial region of the entire wafer surface of the wafer 10, the image sensor 35b may capture only an image of the partial region.

  Further, as shown in FIG. 2A, exposure regions having a mask pattern as a unit are formed at predetermined intervals on the wafer surface by exposure of the exposure apparatus 100. Hereinafter, this exposure area is referred to as a shot 11. Some shots 11 have only one mask pattern exposed, while others have a plurality of mask patterns connected and exposed. In the shot 11, an area that finally becomes a single device after the exposure process is referred to as a chip below. There may be a plurality of chips in the shot 11, or one shot 11 may become one chip.

  In FIG. 1A, the image processing unit 40 is configured to generate a digital image of the wafer 10 based on the image signal of the wafer 10 input from the imaging device 35 (signal intensity for each pixel, signal intensity averaged for each shot, (Or signal intensity averaged for each region smaller than the shot), and a Stokes parameter (to be described later) as an amount defining the state of polarization obtained based on this information is output to the calculation unit 50. Note that the image processing unit 40 is configured to simply output digital image information (information on signal intensity distribution for each pixel, etc.) to the calculation unit 50. The calculation unit 50 includes an inspection unit 60 including calculation units 60a, 60b, and 60c that processes information such as Stokes parameters, a control unit 80 that controls operations of the image processing unit 40 and the inspection unit 60, and an image. A storage unit 85 for storing information and the like, and an evaluation result of processing conditions obtained by the control unit (not shown) of the coater / developer 200 and the control unit of the exposure apparatus 100 via the host computer 600 of FIG. (Not shown) and a signal output unit 90 for outputting to a control unit (not shown) of the etching apparatus 300. The signal output unit 90 may output the evaluation result directly to the coater / developer 200, the exposure apparatus 100, and the etching apparatus 300 without using the host computer 600. Further, the signal output unit 90 may be able to output the evaluation result only to a part of the coater / developer 200, the exposure apparatus 100, and the etching apparatus 300. In FIG. 1A, only the exposure apparatus 100 is shown for convenience of explanation. The image processing unit 40 and the calculation unit 50 may be configured as a whole by a computer, and the image processing unit 40, the inspection unit 60, the control unit 80, and the like may be functions on the computer software.

  In the evaluation apparatus 1, the illumination system 20 includes an illumination unit 21 that emits illumination light, and an illumination-side concave mirror 25 that reflects illumination light emitted from the illumination unit 21 toward the wafer surface as parallel light. The illumination unit 21 emits light having a predetermined wavelength (for example, different wavelengths λ1, λ2, λ3, etc.) out of light from the light source unit 22 according to a command from the control unit 80 and a light source unit 22 such as a metal halide lamp or a mercury lamp. A light control unit 23 for selecting and adjusting the intensity, a light guide fiber 24 for emitting light selected by the light control unit 23 and adjusted in intensity from a predetermined emission surface to the illumination side concave mirror 25, and a light guide fiber 24 And a polarizer 26 (illumination side polarization filter) that linearly polarizes the illumination light emitted from the exit surface. The polarizer 26 is, for example, a polarizing plate having a transmission axis. The polarizer 26 is rotatable about an axis that passes through the center of the surface 26 a on which illumination light emitted from the exit surface of the light guide fiber 24 is incident and is orthogonal to the surface 26 a. That is, the direction of the transmission axis of the polarizer 26 can be set to an arbitrary direction, and the vibration direction of the linearly polarized light converted by the polarizer 26 can be set to an arbitrary direction. The rotation angle of the polarizer 26 (the direction of the transmission axis of the polarizer 26) is controlled by a drive unit (not shown) based on a command from the control unit 80. As an example, the wavelength λ1 is 248 nm, λ2 is 265 nm, and λ3 is 313 nm. In this case, since the exit surface of the light guide fiber 24 is disposed at the focal point of the illumination-side concave mirror 25, the illumination light ILI reflected by the illumination-side concave mirror 25 is irradiated as a parallel light beam onto the wafer surface. The incident angle θ1 of the illumination light ILI with respect to the wafer 10 (the angle formed by the principal ray of the illumination light and the normal of the wafer surface) is determined by the command of the control unit 80 via the drive mechanism (not shown). Adjustment is possible by controlling the position of the emitting portion and the position and angle of the illumination-side concave mirror 25. In the present embodiment, the normal line of the wafer surface is parallel to the normal line CA of the stage 5.

  In this embodiment, the position and angle of the illumination-side concave mirror 25 are controlled by tilting the illumination-side concave mirror 25 about the tilt axis TA of the stage 5, and thereby the illumination light ILI incident on the wafer 10 (wafer surface). Is adjusted. In the present embodiment, as an example, it is composed of diffracted light ILD of a predetermined order m (m is a positive or negative integer other than 0) generated from the repeated pattern 12 (see FIG. 2A) formed on the wafer surface. The parallel light is received by the light receiving system 30.

  In this case, it is assumed that the incident direction of the illumination light ILI on the wafer surface (the direction of the intersection line between the incident surface of the illumination light ILI and the wafer surface) is parallel to a certain periodic direction (repetition direction) of the repetition pattern 12. Where P1 is the period (pitch) in the period direction and λ is the wavelength of the illumination light ILI, the incident angle θ1 of the illumination light ILI and the diffraction angle θ2 of the diffracted light ILD of order m (the principal ray of the diffracted light and the wafer surface) (The angle formed with the normal line) has the following relationship.

sin (θ1) −sin (θ2) = m · λ / P1 (1)
For this reason, when changing the incident angle θ1, the position of the exit portion of the light guide fiber 24 and the position and angle of the illumination-side concave mirror 25 are controlled, and the diffracted light emitted from the wafer 10 and incident on the light receiving system 30 The tilt angle φ2 of the stage 5 is controlled so that the diffraction angle θ2 of the ILD satisfies the relationship of the expression (1).

Since the polarizer 26 is installed on the optical path in this way, an inspection using a change in the polarization state of the diffracted light due to structural birefringence described later (hereinafter also referred to as a polarization inspection for convenience) is performed.
The light receiving system 30 includes a light receiving side concave mirror 31 disposed facing the stage 5 (wafer 10), a quarter wavelength plate 33 disposed on the optical path of light reflected by the light receiving side concave mirror 31, and 1 / And an analyzer 32 (light receiving side polarization filter) disposed in the optical path of the light that has passed through the four-wavelength plate 33, and the front focal point of the imaging optical system 35 a of the imaging device 35 is disposed at the focal point of the light receiving concave mirror 31. ing. For this reason, the parallel light (diffracted light ILD) emitted from the wafer surface is collected by the light receiving side concave mirror 31 and the imaging optical system 35a of the imaging device 35, and an image of the wafer surface is formed on the imaging surface of the imaging device 35b. Imaged. The analyzer 32 is also a polarizing plate having a transmission axis, for example, like the polarizer 26. The analyzer 32 passes through the center of the surface 32a on which the light reflected by the light-receiving side concave mirror 31 is incident, and is rotatable about an axis orthogonal to the surface 32a. That is, the direction of the transmission axis of the analyzer 32 can be set to an arbitrary direction, and the vibration direction of the linearly polarized light converted by the analyzer 32 can be set to an arbitrary direction. The rotation angle of the analyzer 32 (the direction of the transmission axis of the polarizing plate) is controlled by a drive unit (not shown) based on a command from the control unit 80. As an example, the transmission axis of the analyzer 32 can be set in a direction (crossed Nicols) orthogonal to the transmission axis of the polarizer 26. The quarter-wave plate 33 passes through the center of the surface 33a on which the light reflected by the light-receiving side concave mirror 31 is incident, and is rotatable about an axis orthogonal to the surface 33a. The rotation angle of the quarter-wave plate 33 can be controlled by a drive unit (not shown) based on a command from the control unit 80. For example, by processing a plurality of images of the wafer surface obtained by rotating the quarter-wave plate 33, a Stokes parameter that is an amount that defines the polarization state of the diffracted light ILD from the wafer 10 as described later is set. It can be obtained for each pixel.

  Further, an oxide film is formed on the surface of the wafer 10 by a thermal oxidation apparatus or a plasma CVD apparatus according to a process, or a conductive film is formed by a vacuum evaporation apparatus, a sputtering apparatus, a CVD apparatus, or the like. A resist is applied by the coater / developer 200. Then, a predetermined pattern is projected and exposed by the exposure apparatus 100 through a mask with respect to the uppermost resist. After the development of the resist by the coater / developer 200, the wafer 10 is transferred onto the stage 5 of the evaluation apparatus 1. Here, a repetitive pattern 12 (see FIG. 2A) is formed on the upper surface of the wafer 10 transferred onto the stage 5 through exposure and development processes by the exposure apparatus 100 and the coater / developer 200.

  Then, the wafer 10 is transferred by a not-shown alignment mechanism in the course of conveyance, a pattern in a shot of the wafer 10, a mark on the wafer surface (for example, a search alignment mark), or an outer edge (notch, orientation flat, uneven mark on the back surface, etc.) Is transferred onto the stage 5 in a state where alignment is performed with reference to. In the present embodiment, as shown in FIG. 2A, a plurality of shots 11 are arranged in two directions orthogonal to each other at predetermined intervals on the wafer surface, and a circuit pattern of a semiconductor device is included in each shot 11. As an example, a repeated pattern 12 in which a large number of hole patterns are arranged in a predetermined state is formed. In the following, on a plane parallel to the wafer surface, the X axis and the Y axis are taken along two orthogonal arrangement directions of the plurality of shots 11, and the axis perpendicular to the plane including the X axis and the Y axis is the Z axis. Will be described. In the present embodiment, the periodic direction (repeating direction) of the repeated pattern 12 on the wafer surface is a direction (X direction) parallel to the X axis.

  As an example, as shown in an enlarged view in FIG. 2B, the repetitive pattern 12 is a pattern in which a plurality of hole pattern groups 12b are arranged in the X direction at a period P1, and each hole pattern group 12b includes a resist 8 (Or another thin film 8a, see FIG. 3 (a)). A hole pattern 12a formed of a plurality of substantially circular recesses formed in FIG. 3 is arranged in the Y direction at a period P2. As an example, the diameter d of the hole pattern 12a is about 20 to 40 nm, the period P2 of the hole pattern 12a in the hole pattern group 12b is about twice the diameter d, and the period P1 of the plurality of hole pattern groups 12b is It is about 170-300 nm (for example, about 200 nm).

If a general period Px is substituted instead of the period P1 on the right side of Expression (1), the value on the left side of Expression (1) is 2 or less, and therefore the condition for generating at least the first-order diffracted light (m = 1) is The wavelength λ of the incident light is smaller than twice the period Px (the period Px is larger than λ / 2) as follows.
λ / Px <2 That is, λ <2 · Px (2)
For this reason, when the wavelength of the illumination light ILI is the above-described λ1 to λ3 (248 to 313 nm), diffracted light is not generated from the pattern of the period P2 (about 40 to 80 nm), but the period P1 (about 170 nm or more). Diffracted light is generated from the pattern. As a result, for the illumination light ILI, the plurality of hole pattern groups 12b of the repetitive pattern 12 are substantially equivalent to line patterns each having the Y direction as a longitudinal direction, and the repetitive pattern 12 has a Y direction in each direction. A plurality of line patterns having a line width d in the longitudinal direction can also be regarded as a periodic pattern arranged in the X direction with a period P1. For this reason, the periodic direction of the repeating pattern 12 is the X direction, and the period is P1.

  Further, when the repeated pattern 12 is formed on the wafer 10, as an example, a plurality of bright portions MP2 having a width d in the Y direction shown in FIG. In P2-d), a positive resist (dielectric) is exposed to a pattern image having a shape in which a plurality of dark portions MP1 whose longitudinal direction is the X direction are arranged in the Y direction at a period P2. Thereafter, a plurality of bright portions MP4 having a width d in the X direction and a longitudinal direction in the Y direction shown in FIG. 2D and a dark portion MP3 having a width in the X direction (P1-d) and the longitudinal direction in the Y direction are represented by X An image of a pattern having a shape arranged in the direction at a period P1 is superimposed on the resist and exposed. By developing the resist after the double exposure, a repetitive pattern 12 can be formed as an uneven resist pattern. Further, by performing etching using a resist pattern formed after the development, a repeated pattern having the same shape as the repeated pattern 12 can be formed on the base of the resist (a thin film such as an insulating film).

  The repeating pattern 12 may be a pattern made of metal, for example. Furthermore, the repeating pattern is not limited to a hole pattern or a plurality of hole pattern groups, and may be a line and space pattern, for example. In addition, when only the line and space pattern is formed in one shot, when only the hole pattern is formed, both the line and space pattern and the hole pattern are formed. There may be. A single shot 11 often includes a plurality of chip areas, but in FIG. 2A, it is assumed that there is one chip area in one shot for simplicity.

In the present embodiment, as an example, a case will be described in which the inspection unit 60 processes an image on the wafer surface as described later and evaluates (inspects) the exposure conditions of the exposure apparatus 100 as processing conditions.
Here, the exposure conditions are the exposure amount of the exposure apparatus 100 that has exposed the wafer 10 (so-called dose such as exposure energy), the focus position (the position of the image plane of the mask pattern in the optical axis direction of the projection optical system in the exposure apparatus, A projection optical system for exposure by an immersion method, exposure wavelength (center wavelength and / or half-value width), exposure wavelength (center wavelength and / or full width at half maximum), and the like. Temperature of the liquid between the wafer and the like. As an example, the exposure amount when performing double exposure on the resist as described above is, for example, the sum of the exposure amounts in the two exposures. As an example, the evaluation result of the exposure condition is output to a control unit (not shown) in the exposure apparatus 100 via the host computer 600, and the exposure apparatus 100 corrects the exposure condition (for example, offset) according to the evaluation result. Correction of variations and the like).

  An example of a method for performing evaluation or inspection based on a change in the polarization state of reflected light from the wafer surface using the evaluation apparatus 1 configured as described above will be described. In this case, the repetitive pattern 12 on the wafer surface in FIG. 2A is a hole pattern having a plurality of diameters d in the resist 8 (or other thin film 8a), as shown in FIGS. This is a pattern in which a plurality of hole pattern groups 12b including 12a are arranged in the X direction with a period P1.

  Here, as an example, the shape of the hole pattern 12a is a cylindrical shape with a diameter d centering on an axis parallel to the Z axis, and the shape when the diameter d is the design value ds is the ideal shape of the hole pattern 12a. Shape. The design value ds is ½ of the design value of the period P2 in each hole pattern group 12b. If the focus position or exposure amount in the exposure apparatus 100 deviates from an appropriate value, the periods P1 and P2 of the repeated pattern 12 hardly change, but the shape of each hole pattern 12a changes. For this reason, when the shape of each hole pattern 12a is ideal, it can be considered that the shape of the repeating pattern 12 which consists of several hole patterns 12a is ideal. Further, since each hole pattern group 12b can be regarded as a line pattern having a width d with the Y direction as the longitudinal direction, the repetitive pattern 12 having an ideal shape has an X direction with the Y direction as the longitudinal direction. Can be regarded as a pattern in which a plurality of line patterns having a width d and a substantially rectangular sectional shape are arranged in the X direction at a period P1.

  On the other hand, when the exposure amount in the exposure apparatus 100 when forming the repeated pattern 12 is larger than an appropriate value, the diameter d of each hole pattern 12a is as large as the hole pattern 12Aa indicated by the dotted line in FIG. Conversely, when the exposure amount decreases, the diameter d of each hole pattern 12a decreases. When the exposure amount deviates from the appropriate value in this way, the line width d of the line pattern equivalent to each hole pattern group 12b changes, and the ratio between the line width d and the period P1 deviates from the design value.

When the focus position in the exposure apparatus 100 when forming the repeated pattern 12 deviates from an appropriate value, the cross-sectional shape of the hole pattern 12a is trapezoidal like a hole pattern 12Ba shown in an enlarged view in FIG. Become. This means that the cross-sectional shape of the line pattern equivalent to each hole pattern group 12b deviates from the ideal shape.
The evaluation apparatus 1 according to the present embodiment changes the polarization state of diffracted light from the wafer surface (so-called on the wafer surface) accompanying the change in the shape (including the cross-sectional shape) of the hole pattern 12a in the repetitive pattern 12 as described above. The exposure conditions are evaluated using the change in the polarization state of reflected light due to structural birefringence in the repetitive pattern 12. The structural birefringence of a pattern means that the refractive index (apparent refractive index) for incident light in multiple directions (for example, the periodic direction and the direction perpendicular thereto) varies depending on the structure of the pattern. To do. For example, when linearly polarized light enters the pattern, the structural birefringence of the pattern causes the reflected light or diffracted light from the pattern to be elliptically polarized or linearly polarized in a different direction. From the change in the polarization state of light or diffracted light, the change in the pattern structure from the ideal structure, and the change in the processing conditions (exposure conditions, etc.) when the pattern is formed with respect to the target value is evaluated. Can do. The change in the shape of the hole pattern 12 a of the repetitive pattern 12 appears for each shot 11 of the wafer 10 and for each of a plurality of regions in the shot 11.

  In order to evaluate the exposure condition from the change in the polarization state of the diffracted light from the wafer surface using the evaluation apparatus 1 of the present embodiment, the control unit 80 stores recipe information (apparatus condition or evaluation) stored in the storage unit 85. Condition and evaluation procedure) and perform the following processing. In the present embodiment, Stokes parameters S0, S1, S2, and S3 defined by the following equation of light diffracted on the wafer surface are measured as quantities that define the polarization state. Note that the axes orthogonal to each other in the plane perpendicular to the optical axis of the light are the x-axis and the y-axis, and the intensity of the linearly polarized light component (transversely polarized light) in the x direction is Ix, and the linearly polarized light component (longitudinal polarized light) in the y direction. The intensity of the linearly polarized light component in the direction inclined by 45 ° with respect to the x axis (45 ° polarized light) (Ipx) and the intensity of the linearly polarized light component in the direction inclined by 135 ° (−45 °) with respect to the x axis (135 The intensity of (polarized light) is Imx, the intensity of the clockwise circularly polarized component is Ir, and the intensity of the counterclockwise circularly polarized component is Il.

S0 = total intensity of luminous flux (3A)
S1 (intensity difference between horizontally polarized light and vertically polarized light) = Ix−Iy (3B)
S2 (intensity difference between 45 ° polarized light and 135 ° polarized light) = Ipx−Imx (3C)
S3 (intensity difference between clockwise and counterclockwise circularly polarized light components) = Ir-Il (3D)
The Stokes parameter S0 is the square root of the square sum of the other three Stokes parameters S1 to S3, and is normalized so that the Stokes parameter S0 is 1 below. In this case, the values of the other Stokes parameters S1 to S3 are in the range of −1 to +1. The Stokes parameters (S1, S2, S3) are, for example, (0, -1, 0) for perfect 135 ° polarization and (0, 0, 1) for perfect clockwise circular polarization.

  First, the wafer 10 on which the repeated pattern 12 to be inspected is formed on the stage 5 through the steps of resist application in the coater / developer 200, resist exposure in the exposure apparatus 100, and resist development in the coater / developer 200. Is placed at a predetermined position. As an example, the rotation angle of the stage 5 is such that the periodic direction A1 (X direction of the wafer surface) of the repeating pattern 12 on the wafer surface is incident direction A2 of the illumination light ILI on the wafer surface as shown in FIG. Is set to be parallel to

The tilt angle φ2 of the stage 5 is such that the light receiving system 30 can receive the m-order diffracted light ILD from the wafer 10, that is, the light received by the light receiving system 30 with respect to the incident angle θ1 of the incident illumination light ILI. The diffraction angle θ2 with respect to the wafer surface is set so as to be an angle determined by the above-described equation (1). For this reason, the diffraction angle θ <b> 2 is also a light receiving angle by the light receiving system 30.
Further, as an example, the angle of the polarizer 26 is such that the angle ψ formed by the polarization direction A3 (see FIG. 3B) on the wafer surface of the incident illumination light ILI with respect to the periodic direction A1 of the repeated pattern 12 is 45 °. Is set to be This is because the intensity of the component oscillating in the periodic direction A1 (X direction) of the electric vector of the illumination light ILI is equal to the intensity of the component oscillating in the Y direction orthogonal to the periodic direction A1, and from the wafer surface. In order to increase the detection sensitivity, which is a change in the amount (in this case, the Stokes parameter) that defines the polarization state with respect to the change in the exposure condition, by increasing the change in the polarization state due to the structural birefringence of the repeated pattern 12 in is there. However, when the detection sensitivity is increased by setting the angle ψ between the periodic direction A1 and the polarization direction A3 to 0 °, 30 °, 60 °, or the like, the angle ψ may be changed. Note that the angle ψ is not limited to these and can be set to an arbitrary angle. For example, the angle ψ can be set to 22.5 ° or 67.5 °.

  When the angle ψ is 45 °, the linearly polarized illumination light ILI passes through the repetitive pattern 12 in a state where the vibration direction of the electric vector (polarization direction A3) is inclined 45 ° with respect to the periodic direction A1 of the repetitive pattern 12. Incident light traverses in the periodic direction A1. The diffracted light ILD of the m-th order parallel light to be detected diffracted on the wafer surface is collected by the light receiving side concave mirror 31 of the light receiving system 30 and passes through the quarter wavelength plate 33 and the analyzer 32 to the imaging device 35. Reach the imaging surface. At this time, the polarization state of the diffracted light ILD changes to, for example, elliptically polarized light with respect to the linearly polarized light of the incident light due to the structural birefringence in the repeated pattern 12. As an example, the orientation of the transmission axis of the analyzer 32 is set to be orthogonal to the transmission axis of the polarizer 26 (in a crossed Nicols state). Accordingly, the analyzer 32 extracts a polarization component whose polarization direction is substantially perpendicular to the incident illumination light ILI from the diffracted light whose polarization state has changed from the wafer 10 (repetitive pattern 12), and introduces it to the imaging device 35. It is burned. As a result, an image of the wafer surface is formed on the imaging surface of the imaging device 35 by the polarization component extracted by the analyzer 32. It is also possible to take an image of the wafer surface by shifting the angle of the analyzer 32 by a predetermined angle from the crossed Nicols state.

  In the present embodiment, as an example, the Stokes parameters S0 to S3 indicating the polarization state of the reflected light from the wafer surface are obtained by the rotational phaser method. In this case, the rotation angle θ of the quarter-wave plate 33 is set to a plurality of angles (for example, at least four different angles) θi (i = 1, 2,...) Step by step, and the wafer surface at each rotation angle. The image is picked up by the image pickup device 35b, and the obtained image signal is supplied to the image processing unit 40. Information about the rotation angle of the quarter-wave plate 33 is also supplied to the image processing unit 40. At this time, when the Stokes parameter S0 (total intensity of each pixel) is Fourier-transformed with respect to the rotation angle θ of the quarter-wave plate 33, the 0th-order coefficient is a0 / 2, the sin2θ coefficient is b2, and the cos4θ coefficient is a4. When the coefficient of sin 4θ is b4, the Stokes parameters S1, S2, and S3 correspond to the coefficients a4, b4, and b2, respectively. Therefore, the image processing unit 40 can obtain the Stokes parameters S0 to S3.

Note that the rotational phaser method is described as a “method using a rotating λ / 4 plate” in, for example, the document “Tetsuo Tsuruta: Applied Optics II (Applied Physics), p.233 (Baifukan, 1990)”. . A detailed method for calculating the Stokes parameter is also described in Japanese Patent Application Laid-Open No. 2010-249627 filed by the present applicant.
The image processing unit 40 outputs the obtained Stokes parameter information for each pixel of the imaging device 35 to the inspection unit 60. The inspection unit 60 evaluates the exposure conditions in the exposure apparatus 100 used when forming the repeated pattern 12 of the wafer 10 using the information. As described above, when the Stokes parameter for each pixel of the image on the wafer surface is obtained, the incident angle θ1 of the illumination light ILI with respect to the wafer surface in the evaluation apparatus 1 (or the diffraction angle obtained from the equation (1) according to the incident angle θ1). θ2), wavelength λ of illumination light ILI (λ1 to λ3, etc.), rotation angle of polarizer 26 (direction of transmission axis), rotation angle of analyzer 32 (direction of transmission axis), order m of diffracted light ILD to be detected , And the combination of the rotation angle of the stage 5 (orientation of the wafer 10) and the like are called one apparatus condition. The apparatus conditions can also be called evaluation conditions. When the evaluation based on the change in the polarization state is performed as described above, the apparatus condition can also be called a polarization condition. A plurality of device conditions are included in the recipe information of the evaluation device 1 stored in the storage unit 85.

  In the present embodiment, an apparatus condition suitable for evaluating the exposure condition of the pattern formed on the wafer is selected from the plurality of apparatus conditions. As the apparatus conditions, at least one of the wavelength λ, the incident angle θ1, and the angle of the analyzer 32 may be used, or any other condition that can be adjusted in the evaluation apparatus 1 may be used. Note that the wavelength λ of the illumination light ILI, the incident angle θ1 of the illumination light ILI with respect to the wafer surface, and the rotation angle of the polarizer 26 (azimuth of the transmission axis) are examples of illumination conditions, and the rotation of the diffracted light ILD from the wafer surface. The folding angle θ2 (light receiving angle by the light receiving system 30) and the rotation angle of the analyzer 32 (the direction of the transmission axis) are examples of detection conditions of the detection unit, and the rotation angle of the stage 5 (the direction of the wafer 10) and the tilt of the stage 5 The angle φ2 (tilt angle of the wafer surface) is an example of the stage attitude condition.

  In the following description, as an example, the exposure conditions to be evaluated by the exposure apparatus 100 are the exposure amount (first exposure condition or first processing condition) and the focus position (second exposure condition or second processing condition). To do. At this time, when the exposure amount changes, the line width d of the line pattern substantially equivalent to the hole pattern group 12b of the repeated pattern 12 changes (the width of the cross section changes) as described above. When a polarized light beam is incident, as shown in FIG. 4A, the exposure amount during exposure of the pattern is from D1 (a state lower than the optimum value) to D5 (optimum value, so-called best dose amount Dbe). As an example, the polarization state of the reflected light from the wafer surface changes both the major axis direction (slope) and ellipticity of the elliptically polarized light. Further, since the major axis direction of elliptically polarized light corresponds to the Stokes parameter S2 and the ellipticity corresponds to the Stokes parameters S1 and S3, the Stokes parameters S1, S2, and S3 of the reflected light change when the exposure amount changes.

  On the other hand, when the focus position changes, the cross-sectional shape of the pattern changes as described above. Therefore, when a linearly polarized light beam is incident on the wafer surface, as shown in FIG. When the focus position changes from F1 (low state with respect to the optimum value) to F4 (optimum value, so-called best focus position Zbe) to F8 (high state with respect to the optimum value), as an example, reflection from the wafer surface In the polarization state of light, the major axis direction (tilt) of elliptically polarized light is substantially the same, and only the ellipticity tends to change. For this reason, when the focus position changes, the Stokes parameters S1 and S3 of the reflected light change relatively large, and the rate of change of the Stokes parameter S2 tends to be relatively small. By utilizing the fact that the Stokes parameters that change depending on the exposure conditions differ in this way, it becomes possible to inspect individual exposure conditions from the measured values of the Stokes parameters.

  4 (a) and 4 (b) show changes in elliptically polarized light reflected from an actual line-and-space pattern in which the ratio of the width of the line portion to the width of the space portion is 1: 1. Yes. In the repetitive pattern 12 of this embodiment, the part corresponding to the line pattern is actually the hole pattern group 12b, and the part corresponding to the space part (adjacent to the width d of the part corresponding to the line pattern). The width (P1-d) of the region between the two hole pattern groups 12b is about several times, for example. However, it is assumed that the change in the polarization state of the diffracted light from the repetitive pattern 12 due to the change in the exposure condition is qualitatively as shown in FIGS.

  In addition, as described above, the repetitive pattern 12 of the present embodiment changes almost in shape even if the exposure condition changes with respect to the width of the portion corresponding to the line pattern whose shape changes according to the change of the exposure condition. For example, the width of the portion corresponding to the space portion to be not widened is several times as large. In this case, if regular reflection light (0th-order diffracted light) from the wafer surface is detected, there is a small change in the amount that defines the polarization state when the exposure conditions change, so that the detection sensitivity may be lowered. . In contrast, in the present embodiment, first-order or higher-order diffracted light ILD is detected from the repetitive pattern 12 on the wafer surface, and most of the diffracted light ILD is a portion corresponding to the line pattern in the repetitive pattern 12 ( Light from a plurality of hole patterns 12a). For this reason, when the exposure condition is changed, the change (detection sensitivity) of the amount defining the polarization state of the diffracted light ILD due to the change in the shape of the plurality of hole patterns 12a is increased, and the repeated pattern 12 is formed. The exposure conditions can be evaluated with high accuracy.

  Next, in the present embodiment, the evaluation apparatus 1 is used to detect light from a repetitive pattern on the wafer surface, and the exposure conditions (here, exposure amount and focus position) of the exposure apparatus 100 used to form the pattern. ) Will be described with reference to the flowchart of FIG. Since it is necessary to obtain an apparatus condition (evaluation condition) in advance for the evaluation, an example of a method for obtaining the apparatus condition (hereinafter also referred to as condition determination) will be described with reference to the flowchart of FIG. These operations are controlled by the control unit 80.

  First, in order to determine the conditions, a wafer 10a (see FIG. 7A) coated with a resist is prepared in the coater / developer 200 in step 102 of FIG. As shown in FIG. 7A, N shots 11 (N is an integer of about several 10 to 100, for example) are arranged on the surface of the wafer 10a with the scribe line region SL as an example. Hereinafter, the nth shot 11 on the surface of the wafer 10a is referred to as a shot SAn (n = 1 to N). Then, the resist-coated wafer 10a is transported to the exposure apparatus 100 in FIG. 1B, and the exposure apparatus 100 scans the wafer 10a, for example, in the scanning direction during scanning exposure (the direction along the Y axis in FIG. 7A). The exposure amount gradually changes between shots arranged in a), and the focus position gradually changes between shots arranged in a non-scanning direction (direction along the X axis in FIG. 7A) orthogonal to the scanning direction. As described above, a pattern of a mask (not shown) for a device that is actually a product is exposed on each shot SAn while changing the exposure conditions. In the present embodiment, the mask pattern images of FIGS. 2C and 2D are double-exposed.

Thereafter, by developing the exposed wafer 10a, one wafer (hereinafter referred to as a "conditional wafer") 10a in which the repeated pattern 12 is formed on each shot SAn under different exposure conditions is created. .
In the following, it is assumed that a defocus amount with respect to the best focus position Zbe (herein referred to as a focus value) is used as the focus position. With respect to the focus position, as an example, the focus value is set in seven steps from −60 nm to 0 nm to +60 nm in increments of 20 nm. Numbers 1 to 7 of the focus value F on the horizontal axis in FIG. 8B and the like to be described later correspond to the seven stages of focus values (−60 to +60 nm). Note that the focus value can be set in an arbitrary increment and at an arbitrary stage. For example, the focus value can be set at multiple stages in increments of 10 nm or 30 nm. Also, the focus value can be set, for example, in 17 steps from −200 nm to +200 nm in increments of 25 nm.

  As an example, the exposure amount is 7 steps (11.5 mJ, 13.0 mJ, 14.5 mJ, 16.0 mJ, 17.5 mJ, 19.0 mJ, 20. 5 mJ). Numbers 1 to 7 of the exposure amount D on the horizontal axis in FIG. 8A and the like described later correspond to the seven exposure amounts. The exposure amount can also be set at an arbitrary step amount and at an arbitrary stage (for example, 9 stages).

In addition, as an example, the exposure amount and focus value ranges of non-defective products are expressed as permissible ranges EG1 and EG2 (for example, exposure amount and focus value ranges that do not cause malfunction of the device after manufacture), respectively.
The conditionally adjusted wafer 10a of the present embodiment is a so-called FEM wafer (Focus Exposure Matrix wafer) that is exposed and developed by changing the exposure amount and the focus position in a matrix. If the number of shots with different combinations of exposure conditions obtained by the product of the number of focus value stages and the number of exposure dose stages is greater than the number of shots on the entire surface of one conditioned wafer 10a, a plurality of shots It is also possible to create a conditionally adjusted wafer.

  Conversely, for example, when the number of arrangements of shots SAn in the non-scanning direction is larger than the number of stages of change in focus value and / or when the number of arrangements in the scanning direction is larger than the number of stages of change in exposure amount, A plurality of shots having the same value and exposure amount may be formed, and the measurement values obtained for the shots having the same focus value and exposure amount may be averaged. In addition, for example, the influence of subtle application unevenness of the resist between the central portion and the peripheral portion of the wafer, the influence of the difference in the scanning direction of the wafer (+ Y direction or −Y direction in FIG. 7A) at the time of scanning exposure, etc. In order to reduce, a plurality of shots having different focus values and exposure amounts may be arranged at random.

  Next, the created conditioned wafer 10 a is transferred onto the stage 5 of the evaluation apparatus 1. Then, the control unit 80 reads out a plurality of device conditions from the recipe information in the storage unit 85. As a plurality of apparatus conditions, for example, the wavelength λ of the illumination light ILI is any one of the above λ1, λ2, and λ3, and the incident angle θ1 of the illumination light ILI is 10 °, 15 °, 30 °, 45 °, and 60 °. Assuming a condition that the polarizer angle or the polarization angle, which is the rotation angle of the polarizer 26 (the direction of the transmission axis), or the polarization angle is set to any angle in increments of 15 ° from 0 ° to 165 °. To do. In this case, when the polarizer angle is 45 °, the polarization direction A3 of the illumination light ILI incident on the wafer surface is a direction that intersects the periodic direction A1 of the repetitive pattern 12 clockwise at 45 °. Hereinafter, it is assumed that the diffracted light ILD received by the light receiving system 30 is + 1st order diffracted light (m = + 1) as an example. However, -1st order diffracted light or other 2nd order or higher order diffracted light may be received. Here, the wavelength λ is λn (n = 1 to 3), the incident angle θ1 is αm (m = 1 to 6), and the rotation angle of the polarizer 26 is βj (j = 1 to J, where J is an integer of 2 or more). Can be expressed by the condition ε (n−m−j). When the incident angle θ1 is set to a certain angle, the tilt axis TA of the illumination-side concave mirror 25 is centered so that the diffracted light ILD having the diffraction angle θ2 obtained by the above equation (1) is received by the light receiving system 30. The tilt angle φ2 of the stage 5 and / or the stage 5 is adjusted.

Further, the incident angle θ1 may be an arbitrary settable angle, and may be set at an interval of about 5 ° so as to be any one of 10 ° to 85 °, for example. Also, the polarizer angle may be set to a plurality of angles with the reference angle as a center, with the direction intersecting the periodic direction A1 of the repetitive pattern 12 on the wafer surface being 45 °.
Then, in the evaluation apparatus 1, with the conditioned wafer 10a placed on the stage 5, the wavelength of the illumination light ILI is set to λ1 (step 104), and the incident angle θ1 is set to α1 (together with the stage 5). ) (Step 106), the rotation angle of the polarizer 26 (polarizer angle) is set to β1 (step 108), and the quarter-wave plate 33 ( The rotation angle of the phase plate is set to an initial value (step 110). Then, under this apparatus condition, the illumination light ILI is irradiated onto the surface of the conditioned wafer 10a, and the imaging device 35 captures an image of the conditioned wafer 10a based on the diffracted light ILD from the conditioned wafer 10a. The image signal is output to the image processing unit 40 (step 112). Next, it is determined whether or not the quarter-wave plate 33 is set to all angles (step 114). If the quarter-wave plate 33 is not set to all angles, the quarter-wave plate 33 is set to, for example, about 1.41. The angle is rotated by ° (angle obtained by dividing the rotatable angle range 360 ° of the quarter-wave plate 33 by 256) (step 116), and the process returns to step 112 to capture an image of the conditioned wafer 10a. By repeating step 112 until the angle of the quarter-wave plate 33 is rotated by 360 ° in step 114, images of 256 wafers are picked up corresponding to different rotation angles of the quarter-wave plate 33. Since there are four unknowns regarding the Stokes parameters (S0 to S3), the angle of the quarter-wave plate 33 may be set to four different angles, for example, and only four images of the wafer may be captured. Any other number of images may be captured.

  Thereafter, the operation shifts from step 114 to step 118, and the image processing unit 40 sets the Stokes parameters S0 to S3 for each pixel of the image sensor 35b by the above-described rotational phaser method from the obtained digital images of 256 wafers. Ask. In the present embodiment, since the Stokes parameter S0 is standardized to be 1, the Stokes parameters that are actually obtained are S1 to S3 below. These Stokes parameters S1 to S3 are output to the first calculation unit 60a of the inspection unit 60, and the first calculation unit 60a obtains, as an example, an average value for each shot of each Stokes parameter (hereinafter referred to as a shot average value). The output is output to the second calculation unit 60b and the storage unit 85 in correspondence with the apparatus condition ε (n−m−j) and the exposure condition.

  Thereafter, it is determined whether or not the rotation angle of the polarizer 26 is set to all angles (step 120). If not set to all angles, the polarizer 26 is rotated by, for example, 15 ° to an angle β2. Set (step 122) and return to step 110. Then, the Stokes parameter for each pixel of the image on the wafer surface, the shot average value, and the like (steps 110 to 118) are executed by the rotational phaser method. Thereafter, when the rotation angles of the polarizer 26 are set to all the angles βj (j = 1 to J), the process proceeds from step 120 to step 124, and the incident angle θ1 of the illumination light ILI is set to all the angles. If not all angles are set, the illumination system 20 and the stage 5 are driven, the incident angle θ1 is set to α2, and the diffraction angle θ2 is set to a corresponding angle ( Step 126) and return to Step 108. Then, the Stokes parameters for each pixel of the image on the wafer surface, the shot average value, and the like (steps 108 to 122) are executed by the rotational phaser method.

  Thereafter, when the incident angles θ1 are set to all the angles αm (m = 1 to 6), the process proceeds from step 124 to step 128 to determine whether or not the wavelengths λ of the illumination light ILI are set to all the wavelengths. If the wavelength is not set to all wavelengths, the illumination unit 21 changes the wavelength λ to λ2 (step 130) and returns to step 106. Then, the Stokes parameters for each pixel of the image on the wafer surface, the shot average value, and the like (steps 106 to 126) are executed by the rotational phaser method. Thereafter, when the wavelengths λ are set to all the wavelengths λn (n = 1 to 3), the operation shifts from step 128 to step 132.

  In step 132, the second arithmetic unit 60b uses the Stokes parameter information measured for each shot of the conditionally adjusted wafer 10a under the above-described all apparatus conditions, and the Stokes parameters S1 to S3 measured under all the apparatus conditions. Then, a sensitivity (hereinafter also referred to as “dose sensitivity”) that is a change rate of the measurement value with respect to a change in exposure amount, and a sensitivity (hereinafter also referred to as a focus sensitivity) that is a change rate of the measurement value with respect to a change in focus value are obtained.

  In the second calculation unit 60b, among all the apparatus conditions ε (n−m−j), conditions regarding the Stokes parameters S1 to S3 are high in dose sensitivity and lower in focus sensitivity than the dose sensitivity. The first apparatus condition (or first evaluation condition) A is determined. As an example of the first apparatus condition A, the wavelength of the illumination light is λ2, the incident angle θ1 of the illumination light with respect to the wafer surface is 60 °, and the rotation angle (polarizer angle) of the polarizer 26 is 30 °.

  Under the first apparatus condition A, the Stokes parameters S1, S2, and S3 change as shown in FIGS. 8A and 8B with respect to the exposure amount D and the focus value F of the conditionally adjusted wafer 10a, respectively. Numerical values 1 to 7 on the horizontal axis in FIGS. 8A and 8B represent the respective stages when the exposure amount D and the focus value F are changed to the above-described seven stages, and the fourth stage is optimal. Value. The same applies to FIGS. 9A and 9B below. A non-defective range of the exposure amount D is represented by EG1, and a non-defective range of the focus value F is represented by EG2.

  8A and 8B, the solid curve (or broken line; the same applies hereinafter) B11 and B21, the dotted curves B12 and B22, and the dashed curves B13 and B23 are the exposure amount D and the focus value F, respectively. Represents the change of the Stokes parameters S1, S2 and S3 with respect to the change of. Since the change in the Stokes parameters S1 to S3 with respect to the change in the focus value F is smaller than the curves B21, B22, and b23 in FIG. 8B, the ratio of the change in the Stokes parameters S1 to S3 with respect to the change in the focus value F (focus sensitivity). Is low. Further, since the difference between the maximum value and the minimum value of the curves B11, B12, B13 in FIG. 8A is large, it can be seen that the dose sensitivity of the Stokes parameters S1 to S3 is high.

  In practice, a first threshold value and a second threshold value larger than the first threshold value may be determined in advance. At this time, the difference between the maximum value and the minimum value of each of the Stokes parameters S1 to S3 in the entire range of the focus value F (here, all of the seven levels) is smaller than the first threshold value, and the exposure amount. When the difference between the maximum value and the minimum value of each of the Stokes parameters S1 to S3 in the entire range of D (all values in seven stages here) is larger than the second threshold value, the dose sensitivity is high and the focus sensitivity is high. May be considered low. Then, a plurality of device conditions are obtained in which the dose sensitivity is high and the focus sensitivity is low, and the device conditions when the average value of the dose sensitivities of the Stokes parameters S1 to S3, for example, is the highest among the plurality of device conditions. The apparatus condition A may be selected. The average value of dose sensitivity is, for example, the average value of the difference between the maximum value and the minimum value of the Stokes parameters S1 to S3 in the entire range of the exposure dose D.

  Further, in the second arithmetic unit 60b, in order to interpolate the values of the Stokes parameters S1, S2, and S3 at arbitrary values between the seven levels of the exposure dose D, as an example, three values shown in FIG. By approximating the curves B11, B12, and B13 with a higher-order function or exponential function related to the exposure amount D, as shown in FIG. 8C, changes in the Stokes parameters S1, S2, and S3 with respect to the value of the exposure amount D, respectively. Curves B31, B32, and B33 representing are obtained. In addition, the horizontal axis of FIG.8 (c) represents the value of the exposure amount D centering on the best dose amount Dbe. As an example, the curves B32 and B33 are functions that monotonously increase when the exposure dose D increases, and the curve B31 is a function that monotonously decreases when the exposure dose D increases. These curves B31 to B33 are the first reference data. The second computing unit 60b causes the storage unit 85 to store the determined first device condition A and first reference data. The first reference data is, for example, a range of values of a plurality of stages of the Stokes parameters S1 to S3 for the curves B31 to B33 (for example, 100 continuous ranges obtained by equally dividing the range from −1 to +1). May be stored as a table to which the value of the corresponding exposure amount D is assigned. Further, for example, using the curves B31 to B33, a function (higher order function or exponential function) of the Stokes parameters S1 to S3 for calculating the exposure dose D from the values of the Stokes parameters S1 to S3 is obtained. You may memorize | store the function of S1-S3 as the 1st reference data. Thus, the first reference data can be stored in various formats.

  In the next step 134, in the second calculation unit 60b, the focus sensitivity is high and the dose sensitivity is higher than the focus sensitivity with respect to the Stokes parameters S1 to S3 in all the apparatus conditions ε (nm−j). The low condition is determined as the second apparatus condition (or second evaluation condition) B. As an example of the second apparatus condition B, the wavelength of the illumination light is λ1, the incident angle θ1 of the illumination light with respect to the wafer surface is 45 °, and the rotation angle (polarizer angle) of the polarizer 26 is 45 °.

Under the second apparatus condition B, the Stokes parameters S1, S2, and S3 change as shown in FIGS. 9A and 9B with respect to the exposure amount D and the focus value F of the conditionally adjusted wafer 10a, respectively.
9A and 9B, solid curves C11 and C21, dotted curves C12 and C22, and dashed curves C13 and C23 are Stokes parameters S1 and S2 with respect to changes in exposure dose D and focus value F, respectively. And the change in S3. From the curves C11, C12, and C13 of FIG. 9A, since the change in the Stokes parameters S1 to S3 with respect to the change in the exposure amount D is small, the ratio of the change in the Stokes parameters S1 to S3 with respect to the change in the exposure amount D (dose sensitivity). Is low. Moreover, since the difference between the maximum value and the minimum value of the curves C21, C22, and C23 in FIG. 9B is large, it can be seen that the focus sensitivity of the Stokes parameters S1 to S3 is high.

  In practice, as in the case of the first apparatus condition A described above, a third threshold value and a fourth threshold value that is larger than the third threshold value are determined in advance, and the exposure amount D in the entire range. The difference between the maximum value and the minimum value of the Stokes parameters S1 to S3 is smaller than the third threshold value, and the maximum value and the minimum value of the Stokes parameters S1 to S3 in the entire range of the focus value F When the difference is greater than the fourth threshold, it may be considered that the focus sensitivity is high and the dose sensitivity is low. Then, a plurality of device conditions are obtained in which the focus sensitivity is high and the dose sensitivity is low, and the device conditions when the average value of the focus sensitivity of the Stokes parameters S1 to S3 is the highest among the plurality of device conditions are determined. The apparatus condition B may be selected.

  Furthermore, in order to interpolate the values of the Stokes parameters S1, S2, and S3 at arbitrary values between the seven stages of focus values F, the second calculation unit 60b, for example, uses three curves C21 in FIG. 9B. , C22, and C23 are approximated by a higher-order function or an exponential function related to the focus value F, etc., as shown in FIG. 9C, curves C31 representing changes in the Stokes parameters S1, S2, and S3 with respect to the focus value F, respectively. , C32, C33. In addition, the horizontal axis of FIG.9 (c) represents the focus value F centering on the best focus position Fbe. As an example, the curve C31 is a function that changes in a mountain shape when the focus value F increases, the curve C32 is a function that decreases monotonously when the focus value F increases, and the curve C33 increases the focus value F. Is a monotonically increasing function. These curves C31 to C33 are the second reference data. The second calculation unit 60b causes the storage unit 85 to store the determined second device condition B and second reference data. The second reference data is also a table for assigning the corresponding focus value F to a range of values of a plurality of stages of the Stokes parameters S1 to S3, or for calculating the focus value F from the values of the Stokes parameters S1 to S3, for example. It may be stored as a function (higher order function or exponential function) of the Stokes parameters S1 to S3, and can be stored in various forms.

  Here, an example of the result of obtaining the Stokes parameter of the diffracted light actually generated from the conditioned wafer 10a is shown in FIGS. 10 (a) to 11 (b). FIGS. 10A to 11B show, as an example, Stokes parameters S1 to S3 obtained in a plurality of regions in a plurality of shots 11 of the conditionally adjusted wafer 10a under corresponding apparatus conditions. This is a value converted into luminance. 10A and 10B show the distribution of the Stokes parameter S1 obtained under the corresponding apparatus conditions. In the conditionally adjusted wafer 10a, the focus value F changes in the horizontal direction and the exposure amount D changes in the vertical direction. Therefore, the distribution in FIG. 10A shows that the focus sensitivity is high, and FIG. ) Distribution indicates a high dose sensitivity. FIGS. 11A and 11B show the distribution of Stokes parameters S2 and S3 obtained under the corresponding apparatus conditions. The distribution in FIG. 11A indicates that the dose sensitivity and focus sensitivity of the Stokes parameter S2 are both high, and the distribution in FIG. 11B indicates that the dose sensitivity and focus sensitivity of the Stokes parameter S3 are present.

With the above operation, the condition determination for obtaining the apparatus conditions used when the wafer exposure conditions are inspected is completed.
Next, the Stokes parameter of the diffracted light from the wafer surface is measured on the wafer on which the repeated pattern is formed in the actual device manufacturing process, using the two apparatus conditions obtained by the above-mentioned conditions by the evaluation apparatus 1. Then, from the measured Stokes parameters and the first and second reference data, the exposure amount (first exposure condition) and the focus position (second exposure condition) in the exposure conditions of the exposure apparatus 100 are as follows. evaluate. First, a wafer 10 having the same shot arrangement as that in FIG. 7A and serving as an actual product (device) coated with a resist is conveyed to the coater / developer 200 in FIG. 1A and coated with the resist. 10 is transferred to the exposure apparatus 100, and the exposure apparatus 100 exposes a mask (not shown) pattern for an actual product (device) to each shot SAn (n = 1 to N) of the wafer 10. The wafer 10 is transferred to the coater / developer 200 and the wafer 10 is developed. The exposure conditions at this time are optimum values for all shots, the exposure amount is the sum of the best dose amounts determined according to the masks (here, two masks), and the focus position is the best focus. Position.

  However, in actuality, the shot of the wafer 10 is caused by the influence of slight illuminance unevenness in the slit-like illumination area, for example, in the non-scanning direction and stage vibration (including vibration due to disturbance) in the exposure apparatus 100, for example. Variations in exposure amount and focus position may occur for each SAn (each repeated pattern for each shot SAn), and unintentional changes in exposure amount (changes from the best dose amount) and unintentional changes in focus position (best focus) Therefore, the exposure amount and the focus position are individually evaluated.

  In step 150 of FIG. 6, the wafer 10 after resist application, exposure, and development is loaded onto the stage 5 of the evaluation apparatus 1 of FIG. 1A through an alignment mechanism (not shown). And the control part 80 reads the 1st, 2nd apparatus conditions determined by said condition determination from the recipe information of the memory | storage part 85. FIG. First, the apparatus condition is set to the first apparatus condition A where the Stokes parameters S1 to S3 have high dose sensitivity and low focus sensitivity (step 152), and the rotation angle of the quarter-wave plate 33 (phase plate) is initially set. A value is set (step 110A). Then, the illumination light ILI is irradiated onto the wafer surface, and the imaging device 35 outputs an image signal of an image obtained by the diffracted light on the wafer surface to the image processing unit 40 (step 112A). Next, it is determined whether or not the quarter-wave plate 33 is set to all angles (step 114A). If the quarter-wave plate 33 is not set to all angles, the quarter-wave plate 33 is set to about 1.41 °, for example. It rotates by (an angle obtained by dividing the rotation angle range 360 ° by 256) (step 116A), and the process proceeds to step 112A to capture an image of the wafer 10. By repeating step 112A until the angle of the quarter-wave plate 33 is rotated by 360 ° in step 114A, images of 256 wafer surfaces corresponding to different rotation angles of the quarter-wave plate 33 are taken. . The angle of the quarter-wave plate 33 may be set to four different angles, for example, and only four images of the wafer may be taken, or any other number may be used.

  Thereafter, the operation proceeds to step 118A, and the image processing unit 40 obtains Stokes parameters S1, S2, and S3 for each pixel of the imaging device 35 from the obtained digital images of 256 wafers by the above-described rotational phaser method. . The values of these Stokes parameters are output to the first calculation unit 60a of the inspection unit 60, and the first calculation unit 60a obtains an average value (shot average value) for each shot of the Stokes parameters S1 to S3 as an example. 3 is output to the calculation unit 60c and the storage unit 85. Then, it is determined whether or not the inspection is performed under all the apparatus conditions (step 154). If all the apparatus conditions for inspection are not set, the second apparatus condition B is set at step 156 and then the step. Move to 110A. Then, after the acquisition of the Stokes parameters under the second apparatus condition B is completed, the operation proceeds to step 158.

  In step 158, the third calculation unit 60c of the inspection unit 60 calculates the values of the Stokes parameters S1, S2, and S3 for each shot of the wafer 10 obtained under the first apparatus condition A (referred to as S1a, S2a, and S3a). Is applied to the first reference data (curves B31 to B33 in FIG. 8C) stored in step 132 of FIG. 5 described above to determine the value D1x of the exposure amount D of the shot. As an example, in FIG. 8C, values S1a and S3a are applied to curves B31 and B33, respectively, to obtain exposure dose D values D1a and D3a. On the other hand, the slope of the curve B32 is small in the portion corresponding to the value S2a, and the change (error) in the exposure amount D corresponding to the change (error) in the value S2a may be enlarged. Therefore, as an example, the value S2a of the Stokes parameter S2 is not used here, and the average value of the exposure values D1a and D3a obtained from the values of the Stokes parameters S1 and S3 is used as the exposure value D value D1x of the shot. And Similarly, for example, when the value of the Stokes parameter S3 is in a range where the slope of the curve B33 is small, the value of the exposure amount D can be obtained from only the values of the Stokes parameters S1 and S2 without using the value of the Stokes parameter S3. Good. Note that three values of the exposure amount D may be obtained by applying the values of the three Stokes parameters S1 to S3 to the curves B31 to B33, respectively, and an average value of these three values may be used as the value D1x of the exposure amount D. In this way, the value of the exposure amount D is obtained from the values of the Stokes parameters S1 to S3 for all shots of the wafer 10.

  Then, the third calculation unit 60 c calculates a distribution (error distribution) of a difference (error) from the best dose amount Dbe of the exposure amount D for each shot of the wafer 10, and outputs this to the control unit 80. This error distribution also includes information on whether or not the exposure amount D of each shot is within the non-defective range EG1. The control unit 80 stores the error distribution of the exposure amount D for each shot in the storage unit 85 and displays it on a display device (not shown). For example, the third calculation unit 60c may output the calculated exposure amount D to the control unit 80 without obtaining the error distribution of the exposure amount D. Further, the control unit 80 may not display the error distribution of the exposure dose D or the exposure dose D on the display device.

  In the next step 160, the third calculation unit 60c uses the values of the Stokes parameters S1, S2, and S3 (S1b, S2b, and S3b) for each shot of the wafer 10 obtained in the second apparatus condition B as described above. The focus value F1x of the shot is obtained by applying to the second reference data (curves C31 to C33 in FIG. 9C) stored in 134. As an example, in FIG. 9C, focus values F2b and F3b are obtained by applying values S2b and S3b to curves C32 and C33, respectively. On the other hand, since the curve C31 changes in a mountain shape with respect to the focus value F, two focus values F1b and F4b are obtained corresponding to the value S1b of the Stokes parameter S1. At this time, of the two values F1b and F4b, the value F1b closer to the values F2b and F3b obtained from the other curves C32 and C33 is selected as the actual focus value F. As an example, an average value of the three focus values F1b, F2b, and F3b thus determined is set as the focus value F1x of the shot. In this way, the focus value F is obtained from the values of the Stokes parameters S1 to S3 for all shots of the wafer 10.

  Then, the third calculation unit 60 c calculates a difference (error) distribution (focus position error distribution) from the best focus position Fbe of the focus value F for each shot of the wafer 10, and outputs this to the control unit 80. This error distribution also includes information on whether or not the focus position of each shot is within the non-defective range EG2. The control unit 80 stores the error distribution of the focus position for each shot in the storage unit 85 and displays it on a display device (not shown). For example, the third calculation unit 60c may output the calculated focus position to the control unit 80 without obtaining the error distribution of the focus position. The control unit 80 may not display the focus position error distribution and the focus position on the display device.

  After that, under the control of the control unit 80 of the evaluation apparatus 1, the exposure error distribution for each shot of the wafer 10 is transferred from the signal output unit 90 to the control unit (not shown) of the exposure apparatus 100 via the host computer 600. Information on (exposure unevenness) and focus position error distribution (defocus amount distribution) is provided (step 162). In response to this, a control unit (not shown) of the exposure apparatus 100 sets the exposure amount and / or the focus position when, for example, the unevenness of the exposure amount and / or the distribution of the defocus amount exceeds a predetermined allowable range. In order to correct, for example, correction of the width distribution in the scanning direction of the illumination area at the time of scanning exposure and / or adjustment of the offset of the height of the wafer surface is performed. This reduces the exposure error and the defocus amount during the subsequent exposure. Thereafter, in step 164, the exposure apparatus 100 exposes the wafer under the corrected exposure conditions.

  According to this embodiment, the Stokes parameter is detected under two apparatus conditions using the wafer 10 on which a pattern for a device that is actually a product is formed, and the conditions shown in FIG. By applying the detected Stokes parameter value to the first and second reference data obtained in the extraction step, the exposure amount and the focus position in the exposure condition of the exposure apparatus 100 used at the time of forming the pattern Can be requested. At this time, since the sensitivity to the focus position of the Stokes parameters S1 to S3 is low in the first device condition A, the values of the Stokes parameters S1 to S3 detected under the first device condition A are used. Even if the focus position when the wafer 10 is exposed deviates from an appropriate value, the exposure amount can be obtained with high accuracy without being substantially affected by the focus position.

  Further, in the second apparatus condition B, since the sensitivity to the exposure amount of the Stokes parameters S1 to S3 is low, by using the values of the Stokes parameters S1 to S3 detected under the second apparatus condition B, the wafer is used. Even if the exposure amount at the time of exposing 10 deviates from an appropriate value, the focus position can be obtained with high accuracy without being substantially affected by the exposure amount.

  In other words, the ratio (sensitivity) of the change in the Stokes parameter with respect to the change in the exposure amount and the focus position is different in each apparatus condition, and the change in the Stokes parameter with respect to the change in the exposure amount and the focus position is also between the two apparatus conditions. By utilizing the fact that the ratios (sensitivities) of each other are different from each other, the exposure amount and the focus position can be individually evaluated and inspected with high accuracy. Therefore, by correcting the exposure conditions in the exposure apparatus 100 based on this evaluation result, the exposure conditions for subsequent wafers can be brought closer to an appropriate range, and the device can be manufactured with high accuracy and high yield.

  As described above, the evaluation direction and the evaluation apparatus 1 of the present embodiment evaluates the exposure conditions of the pattern formed on the wafer 10 under predetermined exposure conditions (exposure amount, focus position, etc.) as an example of processing conditions. And a device. Then, the evaluation method irradiates linearly polarized illumination light ILI (polarized light) onto the surface (wafer surface) of the wafer 10 as an example of the evaluation target substrate on which the repetitive pattern 12 as an example of the evaluation target pattern is formed. Step 112A, Steps 112A and 118A for receiving the diffracted light ILD emitted from the wafer surface by irradiation of the illumination light ILI and detecting the Stokes parameters S1 to S3 (the amount defining the polarization state) of the received diffracted light ILD; And 158 and 160 for evaluating the exposure conditions when the repeated pattern 12 is formed based on the detected Stokes parameters S1 to S3.

  The evaluation apparatus 1 also includes an illumination system 20 (illumination unit) that irradiates the surface of the wafer 10 on which the repeated pattern 12 is formed with linearly polarized illumination light ILI, and diffracted light emitted from the wafer surface by the illumination light ILI. Based on the imaging device 35 and the image processing unit 40 (detection unit) that receive the ILD and detect the Stokes parameters S1 to S3 of the diffracted light ILD, and the repetitive pattern based on the detected Stokes parameters S1 to S3 of the diffracted light ILD And an operation unit 50 (evaluation unit) that evaluates the exposure conditions when forming 12.

  According to the present embodiment, the Stokes parameters S1 to S3 are detected and determined in advance using the wafer 10 having the repetitive pattern 12 for a device that is actually a product provided by exposure under predetermined exposure conditions. The detected Stokes parameters S1 to S4 are applied to the first and second reference data (curves B31 to B33 in FIG. 8C and curves C31 to C33 in FIG. 9C). Thus, the exposure conditions in the exposure apparatus 100 when the repeated pattern 12 is formed are obtained. At this time, since the Stokes parameters can be detected under the apparatus conditions (evaluation conditions) in which the change in the values of the Stokes parameters S1 to S3 is large with respect to the change in the exposure conditions, that is, the apparatus conditions in which the sensitivity of the Stokes parameters is high, it is repeated. Using the wafer 10 on which the pattern 12 is formed, the exposure conditions when the repeated pattern 12 is formed can be evaluated with high accuracy and efficiency.

  Further, in this embodiment, since the diffracted light ILD from the wafer 10 is detected and the Stokes parameter of the diffracted light ILD is obtained, the repeated pattern 12 has a portion (hole) whose shape changes greatly according to changes in exposure conditions. The width in the X direction of the portion (flat portion between the plurality of hole pattern groups 12b) whose shape hardly changes even when the exposure condition changes is larger than the width in the X direction (periodic direction) of the pattern group 12b). Even with such a pattern, the Stokes parameter changes greatly with respect to changes in exposure conditions. For this reason, the exposure conditions when the repeated pattern 12 is formed can be evaluated with high accuracy.

  Of the conventional methods for evaluating the focus position as the exposure condition, the method of measuring the lateral shift amount of the resist pattern is difficult to increase the measurement efficiency and illuminates the mask evaluation pattern with illumination light whose chief ray is inclined. Therefore, it has been difficult to accurately measure the focus position when performing exposure using an actual device pattern. On the other hand, according to the present embodiment, an actual device pattern can be used, and it is not necessary to measure the shape of the formed resist pattern. Therefore, in the process of forming the actual device pattern The exposure conditions can be obtained efficiently and with high accuracy.

  Further, in the present embodiment, the calculation unit 50 has first and second apparatus conditions (first and second evaluation conditions) for evaluating exposure conditions when the repeated pattern 12 is formed on the surface of the wafer 10. Is obtained based on the Stokes parameters S1 to S3 of the diffracted light from the surface of the conditionally adjusted wafer 10a on which the repetitive pattern 12 is formed with a known combination of exposure conditions (for example, exposure amount and focus position) (steps 104 to 104). 136). As a result, when the wafer 10 is evaluated, the Stokes parameters need only be obtained using the obtained apparatus conditions or evaluation conditions, so that the wafer 10 can be evaluated efficiently.

  Further, in this embodiment, since the pattern processing condition (exposure condition) is evaluated using the amount that defines the polarization of the diffracted light, for example, it is diffracted more than when the amount that defines the polarization of the regular reflection light is used. More device conditions can be selected using the conditions such as the order as the device conditions. Therefore, in determining the conditions, it is possible to obtain a highly sensitive apparatus condition and reference data for each processing condition (exposure condition), and to evaluate the processing condition (exposure condition) with higher accuracy.

  The device manufacturing system DMS of the present embodiment includes an exposure system. The exposure system includes an exposure apparatus 100 as a processing apparatus that forms a pattern on the surface of the wafer 10 (substrate), and the evaluation apparatus 1 of the present embodiment. And the exposure conditions of the exposure apparatus 100 are adjusted according to the evaluation result of the evaluation apparatus 1. According to this exposure system, the exposure apparatus 100 can be efficiently and highly accurately used so that a pattern having a target shape is formed on the surface of the wafer using a wafer that is actually used for device manufacture. The exposure conditions in can be adjusted.

In the above embodiment, the following modifications are possible.
First, in the above embodiment, the first and second reference data (curves B31 to B33 in FIG. 8C and curves C31 to C33 in FIG. 9C) are obtained by the calculation unit 50 of the evaluation device 1. However, the reference data may be obtained by, for example, the host computer 600 as an arithmetic device different from the evaluation device 1. In this case, the reference data is supplied from the host computer 600 to the control unit 80 of the calculation unit 50 of the evaluation apparatus 1, and the control unit 80 stores the reference data in the storage unit 85. Then, as shown in FIG. 6, when obtaining the exposure conditions, the reference data stored in the storage unit 85 may be used.

  Moreover, in said embodiment, although the pattern of evaluation object is a pattern which consists of several hole pattern 12a, the pattern of evaluation object is orthogonal to the predetermined direction, for example with the several line pattern which makes a predetermined direction a longitudinal direction. A line and space pattern periodically arranged in the direction may be used. The ratio between the line width of the line pattern and the width of the space portion is arbitrary, and may be approximately 1: 1, for example.

  Moreover, in said embodiment, incident angle (theta) 1 (diffraction angle (theta) 2) of illumination light controls the position of the injection | emission part of the light guide fiber 24, and the position and angle of the illumination side concave mirror 25 via a drive mechanism not shown. And adjusting the tilt angle φ2 of the wafer 10 through the second driving unit. In addition to this adjustment method, the diffraction angle θ2 of the diffracted light ILD detected by the light receiving system 30 is adjusted by controlling the position and angle of the imaging device 35 while tilting the light receiving concave mirror 31 about the tilt axis TA. May be.

  In the above embodiment, the exposure conditions are evaluated using the Stokes parameters S1 to S3. However, the exposure condition may be evaluated using at least one of the Stokes parameters S0 to S3. Further, different Stokes parameters may be used when evaluating the exposure amount and the focus position in the exposure conditions.

  In the above embodiment, both the exposure amount and the focus position in the exposure conditions are evaluated. However, at least one of the exposure amount and the focus position may be evaluated. When only the exposure amount is obtained, the exposure amount may be obtained from the value of the Stokes parameter obtained under the first apparatus condition A in step 158 of FIG. When only the focus position is obtained, the focus position may be obtained from the value of the Stokes parameter obtained in the second apparatus condition B in step 160 without executing step 158 in FIG.

In the above embodiment, the exposure amount and the focus position are evaluated as the exposure conditions. As the exposure conditions, the exposure light wavelength, the illumination conditions (for example, the coherence factor (σ value), and the projection optical system in the exposure apparatus 100 are evaluated. In order to evaluate the numerical aperture of the liquid or the temperature of the liquid during the immersion exposure, the evaluation of the above embodiment may be used.
In the above embodiment, the exposure condition is evaluated as the processing condition. However, the film thickness condition in the coater / developer 200 as the processing condition is evaluated together with the exposure condition or separately from the exposure condition. May be. The film thickness condition includes a set value of the film thickness of the resist applied to the wafer, variations in the film thickness, and the like.

  When evaluating the film thickness conditions using the evaluation apparatus 1, as an example, a plurality of wafers coated with resists with different film thicknesses by the coater / developer 200 in the process corresponding to the condition determination of FIG. After preparing and exposing each shot of these wafers with the exposure apparatus 100, those wafers are developed and the pattern 12 is formed repeatedly. Thereafter, the Stokes parameters of the diffracted light from the wafers are detected under a plurality of apparatus conditions, and the value of at least one Stokes parameter among the Stokes parameters S1 to S3 is detected with respect to the change in the resist film thickness. The apparatus condition to be increased is obtained, and reference data indicating the relationship between the Stokes parameter and the film thickness is obtained. Thereafter, in the process corresponding to the evaluation method of FIG. 6, the Stokes parameters detected under the apparatus conditions are applied to the reference data, so that the resist film thickness of the wafer 10 on which the repetitive pattern 12 is formed is determined. The average value and the variation for each shot can be obtained.

Furthermore, film thickness conditions and exposure conditions can also be evaluated by using a plurality of wafers having different film thicknesses as the above-described FEM wafers.
In addition, when an oxide film or a conductive film is formed as a resist base in the substrate exposed by the exposure apparatus, a pattern such as an oxide film or a conductive film is formed by a process such as etching after developing the resist. The In order to form this pattern with high accuracy, it is preferable to evaluate the film thickness conditions of the oxide film or the conductive film. In this case, the above-described resist film is obtained by placing the wafer on which the pattern of the oxide film or conductive film is formed on the stage 5 in FIG. 1A and obtaining the Stokes parameter of the diffracted light from the wafer. Similarly to the case where the thickness is evaluated, the film thickness condition of the oxide film or the conductive film can also be evaluated.

In the above embodiment, the wafer is evaluated under two apparatus conditions (evaluation conditions). However, the wafer may be evaluated under at least one apparatus condition (evaluation conditions). . Further, the wafer may be evaluated under three or more apparatus conditions (evaluation conditions).
In the above embodiment, the obtained Stokes parameter value is applied to the reference data to obtain the exposure conditions and the like. However, in a process corresponding to the condition determination process in FIG. For example, simultaneous equations for calculating a plurality of machining conditions to be evaluated may be obtained from the Stokes parameters S1 to S3 (or two of them). In this case, in the process corresponding to the evaluation process of FIG. 6, the value of the machining condition to be evaluated is obtained simply by substituting the values of Stokes parameters S1 to S3 and the like detected under the apparatus conditions into the simultaneous equations. be able to.

  Further, the wavelength λ, the incident angle θ1, and the rotation angle of the polarizer 26 included in the first and second apparatus conditions are merely examples, and the apparatus conditions include other arbitrary values that can be changed by the evaluation apparatus 1. Conditions can be included. For example, the condition that the rotation angle of the analyzer 32 is set to a plurality of angles at intervals of, for example, an arbitrary angle (for example, about 5 °) around the crossed Nicol state, the order m of the diffracted light to be detected, and the stage 5 A rotation angle (an angle in the periodic direction A1 of the repetitive pattern 12 of the wafer 10 with respect to the incident direction A2 of the illumination light ILI (an orientation of the wafer 10)) or the like can be included in the apparatus conditions.

  Further, in step 118, all shots SAn (see FIG. 7B) except for the scribe line region SL of the condition-controlled wafer 10a (region that becomes a boundary when chips are separated in the device dicing process) are supported. The Stokes parameters of the pixels to be calculated may be calculated, and the calculation results may be averaged to obtain the shot average value. The reason why the shot average value is calculated in this way is to suppress the influence of the aberration of the projection optical system of the exposure apparatus 100 and the like. In order to further suppress the influence of the aberration or the like, for example, a value obtained by averaging the Stokes parameters of the corresponding pixels in the partial area CAn in the central portion of the shot SAn in FIG.

  However, the influence of the aberration of the projection optical system (error distribution given to the digital image) can be obtained in advance, and the influence of the aberration can be corrected at the stage of the digital image. In this case, instead of the shot average value, the average value is calculated for each setting region 16 (see FIG. 7C) such as a rectangle of I (I is an integer of several tens) within the shot SAn. For example, the subsequent processing may be performed using the average value of the setting area 16 at the same position in the shot SAn. The arrangement of the setting areas 16 is, for example, 8 rows in the scanning direction and 6 columns in the non-scanning direction, but the size and arrangement are arbitrary.

Further, when the wafer 10 is evaluated, the average value of the Stokes parameters may be detected for all the setting areas 16 in all shots of the wafer, and the exposure conditions and the like may be evaluated for each setting area 16.
Further, in step 162 in FIG. 6, information on the error distribution (dose unevenness) of the exposure amount on the entire surface of the wafer 10 and the error distribution (defocus amount distribution) of the focus position is obtained from the signal output unit 90 from the host computer 600. It may be output directly to a control unit (not shown) of the exposure apparatus 100 without going through.

  In the above-described embodiment, whether or not these amounts are in the non-defective range is evaluated from the exposure amount D and the focus position F obtained from the Stokes parameters. On the other hand, for example, when the Stokes parameters S1 and S2 are obtained under a certain apparatus condition and the exposure amount D is evaluated from these values, the non-defective range is determined in the two-dimensional distribution of the Stokes parameters S1 and S2. It is possible to set this two-dimensional distribution as reference data for determining the quality of the exposure amount. In this case, the values of the parameters S1 and S2 may be represented by (S1, S2), and the non-defective product range may be approximately inside a circle having the following center coordinates (sa, sb) and radius sr. When the value obtained by substituting the measured parameter values (S1, S2) into the arithmetic expression on the left side of Equation (5) satisfies Equation (5), the measured value is such that the exposure amount D is within the non-defective range. You are doing something.

(S2-sa) ² + (S3-sb) ² ≦ sr ² (5)
Similarly, regarding the focus position, a non-defective range or the like may be set in a two-dimensional distribution of Stokes parameters S1, S2 (or S2, S3, etc.).
In the above-described embodiment, the exposure amount and the focus position are obtained by applying the values of the three Stokes parameters S1 to S3 to the reference data. In addition, a set of values of the Stokes parameters S1, S2, and S3 obtained under a certain apparatus condition (evaluation condition) in the evaluation apparatus 1 may be expressed on the Poincare sphere. In this case, as an example, from a certain point on the Poincare sphere (for example, a point set in a step corresponding to the condition setting step in FIG. 5) to a point determined by a set of values of the three Stokes parameters S1, S2, and S3. An exposure amount or a focus position can be obtained from the distance.

  In the above-described embodiment, the reference data (the curves B31 to B33 in FIG. 8C and the curves B31 to B33 in FIG. 8C) are used by using the conditioned wafer 10a on which the repeated pattern is formed by exposure of the exposure apparatus 100 in the condition setting in FIG. Curves C31 to C33) of (c) were obtained, and using this reference data, the exposure conditions (exposure amount and focus position) of the exposure apparatus 100 used for determining the conditions were obtained during the evaluation of FIG. However, at the time of evaluation in FIG. 6, an exposure apparatus (not shown) different from the exposure apparatus 100 using the reference data (curves B31 to B33 in FIG. 8C and curves C31 to C33 in FIG. 9C). The exposure conditions may be obtained. In this case, a wafer on which a pattern is formed by an exposure apparatus different from the exposure apparatus 100 may be evaluated as in steps 158 to 160 in FIG. 6 and the exposure apparatus may be corrected as in step 162. Further, the wafer on which the pattern is formed by the exposure apparatus 100 is evaluated as in steps 158 to 160 in FIG. 6 described above, and the exposure apparatus different from the exposure apparatus 100 is corrected in step 162 from the evaluation result. Good.

Further, the inspection unit 60 may not only determine the exposure conditions (processing conditions) but also determine the quality of the determined exposure conditions. In this case, the signal output unit 90 may provide a warning to the exposure apparatus 100 or the host computer 600 that the exposure conditions are not appropriate based on the quality determination result. This pass / fail judgment may be performed, for example, by comparing the obtained exposure condition with a predetermined threshold value.
Further, at least one of the apparatus conditions and the reference data obtained by determining the conditions of the evaluation apparatus 1 is used in another machine of the evaluation apparatus 1, and the repetitive pattern formed on the wafer surface in the actual device manufacturing process with the machine. The processing conditions may be evaluated. The modification of the first embodiment described above can also be applied to the second embodiment described below.

[Second Embodiment]
A second embodiment will be described with reference to FIGS. Also in this embodiment, the device manufacturing system DMS in FIG. 1B is used, and the evaluation apparatus 1 in FIG. 1A is used to evaluate the processing conditions. In the present embodiment, the processing conditions of a wafer on which a repetitive pattern with a fine period is formed by a so-called spacer double patterning method (or sidewall double patterning method) are evaluated.

  In the spacer double patterning method, first, as shown in FIG. 12A, the surface of the hard mask layer 17 of the wafer 10d is coated with a resist by the coater / developer 200, the pattern is exposed by the exposure apparatus 100, and developed. Thus, a repetitive pattern 13 composed of a line-and-space pattern in which line portions 3A of a plurality of resist patterns are arranged at a period P is formed. When the illumination light ILI is irradiated on the repetitive pattern 13, regular reflection light ILR and first-order diffracted light ILD are generated. Thereafter, as shown in FIG. 12B, the line portion 3A is reduced to a line portion 3B having a line width of 1/2 by slimming, and a spacer layer 18 is deposited so as to cover the line portion 3B with a thin film forming apparatus (not shown). To do. Thereafter, only the spacer layer 18 of the wafer 10d is etched by the etching apparatus 300, and then only the line portion 3B is removed by the etching apparatus 300, whereby the line width is formed on the hard mask layer 17 as shown in FIG. A repetitive pattern is formed in which a plurality of spacer portions 18A of approximately P / 4 are arranged with a period P / 2. Thereafter, by etching the hard mask layer 17 using the plurality of spacer portions 18A as a mask, the hard mask portions 17A having a line width of approximately P / 4 are arranged with a period P / 2 as shown in FIG. A repeated pattern 17B is formed. Thereafter, as an example, by repeating the device layer 10da of the wafer 10d using the repetitive pattern 17B as a mask, a repetitive pattern with a very fine period can be formed. Furthermore, it is also possible to form a repeating pattern with a period of P / 4 by repeating the above steps.

  When the evaluation apparatus 1 is used to illuminate the wafer 10d with the illumination light ILI and detect the diffracted light ILD from the repetitive pattern 17B of the wafer 10d, the wavelength λ of the illumination light ILI is the period of the repetitive pattern 17B as described above. It is necessary to be smaller than twice (P / 2). However, when there is a pattern block in which the repeated pattern 17B is arranged with a larger period, it is possible to detect diffracted light from this pattern block. In this case, the wavelength λ of the illumination light ILI can be made longer.

Furthermore, in the present embodiment, as processing conditions of the repetitive pattern 17B by the device manufacturing system DMS, the deposition time ts (thin film deposition amount) of the spacer layer 18 in FIG. 12B by the thin film forming apparatus (not shown), and the etching apparatus Assume that the etching time te (etching amount) of the spacer layer 18 by 300 is evaluated.
In this case, in the process corresponding to the condition setting process of FIG. 5, the spacer double patterning process of FIGS. 12A to 12D is combined with, for example, five kinds of deposition times ts and five kinds of etching times te. The process is executed by 25 (= 5 × 5) processes, and a repeated pattern 17B is formed on each shot of 25 conditioned wafers (not shown). It is assumed that the best deposition time (appropriate deposition time) is tsbe and the best etching time (appropriate etching amount) is teve.

  A plurality of (25 in this case) created conditionally adjusted wafers are sequentially transferred onto the stage 5 of the evaluation apparatus 1 in FIG. Each of the plurality of conditionally adjusted wafers is irradiated with linearly polarized illumination light ILI under the plurality of apparatus conditions ε (n−m−j), and the imaging unit 35 and the image processing unit 40 As in the first embodiment, Stokes parameters S1 to S3 of, for example, the first-order diffracted light ILD from the conditionally adjusted wafer are obtained by the rotational phaser method. Then, the calculation unit 50 obtains a first device condition C in which the sensitivity of the Stokes parameters S1 to S3 with respect to the deposition time ts is high and the sensitivity of the Stokes parameters S1 to S3 with respect to the etching time te is low. Furthermore, by interpolating a curve (not shown) indicating the relationship between the Stokes parameters S1 to S3 obtained under the first apparatus condition C and the deposition time ts, as shown in FIG. Curves D11, D12, D13 (first reference data) indicating the relationship between the parameters S1, S2, S3 and the deposition time ts are obtained. The horizontal axis of FIG. 12E is the deposition time ts of the spacer layer 18 centered on the best deposition time (appropriate deposition time) tsbe, and the non-defective range EG3 of the deposition time ts is also shown.

  Further, a second apparatus condition D is obtained in which the sensitivity of the Stokes parameters S1 to S3 with respect to the etching time te is high and the sensitivity of the Stokes parameters S1 to S3 with respect to the deposition time ts is low. Further, by interpolating a curve (not shown) indicating the relationship between the Stokes parameters S1 to S3 obtained under the second apparatus condition D and the deposition time ts, as shown in FIG. Curves D21, D22, D23 (second reference data) indicating the relationship between the parameters S1, S2, S3 and the etching time te are obtained. The horizontal axis of FIG. 12F is the etching time te of the spacer layer 18 centering on the best etching time (appropriate etching amount) teve, and the non-defective range EG4 of the etching time te is also shown.

  Thereafter, in a process corresponding to the evaluation process of FIG. 6, the wafer 10 d on which the repeated pattern 17 </ b> B of FIG. 12D for actual device manufacture is formed is placed on the stage 5 of the evaluation apparatus 1. The imaging unit 35 and the image processing unit 40 are configured to calculate the Stokes parameters S1 to S3 of the first-order diffracted light ILD from the wafer 10d under the first apparatus condition C and the second apparatus condition D, respectively, by the rotational phaser method. Find the value. Then, the Stokes parameters S1 to S3 obtained under the first apparatus condition C are applied to the curves D11 to D13 (first reference data) in FIG. Time ts and this error distribution are obtained. Similarly, by applying the Stokes parameters S1 to S3 obtained under the second apparatus condition D to the curves D21 to D23 (second reference data) in FIG. Find the error distribution.

  Further, under the control of the control unit 80, an error distribution (uneven film thickness) of the deposition time ts of the spacer layer 18 on the entire surface of the wafer 10 is transmitted from the signal output unit 90 to the thin film forming apparatus (not shown) via the host computer 600. ) Information is provided. In response to this, the thin film forming apparatus adjusts, for example, the deposition time. Similarly, the error output (etching unevenness) information of the etching time te on the entire surface of the wafer 10 is provided from the signal output unit 90 to the etching apparatus 300 via the host computer 600. In response to this, the etching apparatus 300 adjusts the etching time, for example. As a result, the repeated pattern 17B having the period P / 2 can be manufactured with high accuracy during the subsequent spacer double patterning process.

Further, as processing conditions in the double patterning process, in addition to the etching amount and the spacer deposition amount, for example, exposure conditions (exposure amount, focus position, etc.) in the exposure apparatus 100 and / or film thickness conditions in the coater / developer 200. You may make it evaluate (setting value etc. of the film thickness of a resist).
Note that the reference data of FIGS. 12E and 12F may also be created by the host computer 600, and the created reference data may be stored in the storage unit 85 of the evaluation apparatus 1.

  In each of the above embodiments, the illumination system 20 of the evaluation apparatus 1 in FIG. 1A collectively illuminates the entire surface of the wafers 10 and 10d with linearly polarized illumination light ILI (polarized light), The imaging device 35 (detection unit) includes an imaging element 35b that captures an image of the entire surface of the wafer 10, 10d. For this reason, the processing conditions of the repeated patterns 12 and 17B formed on each shot on the entire surface of the wafers 10 and 10d can be efficiently evaluated.

  On the other hand, an illumination system that illuminates a part of the surface of the wafer 10 (test substrate) with polarized light, an imaging device that captures an image of a part of the surface of the wafer 10, and a surface parallel to the surface of the wafer 10. An evaluation apparatus (not shown) including a stage movable in the X direction and the Y direction may be used. In the evaluation apparatus of this modification, the wafer 10 is moved by the stage so that the entire surface of the wafer 10 is sequentially irradiated with polarized light from the illumination system. In this modification, the surface of the wafer 10 is divided into a plurality of portions, and the processing conditions of the repeated pattern 12 formed in each portion are sequentially evaluated. Since the evaluation apparatus of this modification can be reduced in size, for example, it can be incorporated in the exposure apparatus 100 on-body. In this case, since the stage of the evaluation apparatus can also be used as the wafer stage (not shown) of the exposure apparatus 100, the configuration of the evaluation apparatus can be further simplified.

In each of the above embodiments, the Stokes parameter is obtained by the rotational phaser method. However, the Stokes parameter may be obtained by the rotational analyzer method. In the rotational analyzer method, instead of rotating the quarter-wave plate 33, a plurality of images are taken while rotating the analyzer 32, and Stokes parameters S0 to S3 are obtained from the obtained plurality of images.
In each of the above embodiments, the amount that defines the polarization state of light from the wafer is represented by a Stokes parameter. However, the quantity that defines the polarization state may be represented by a Jones vector (Jones Vector) composed of two rows of complex column vectors for representing the polarization characteristics of the optical system in the so-called Jones notation. The Jones notation is described, for example, in the reference `` M. Totzeck, P. Graeupner, T. Heil, A. Goehnermeier, O. Dittmann, DSKraehmer, V. Kamenov and DGFlagello: Proc. SPIE 5754, 23 (2005) ''. As shown, a Jones matrix (Jones Matrix) composed of a 2 × 2 complex matrix (polarization matrix) for representing the polarization characteristics of the optical system, and a polarization state converted by the optical system It is described by Jones vector.

Further, a condition that defines the state of polarization may be expressed using both the Stokes parameter and the Jones vector. Furthermore, the conditions that define the state of polarization can be expressed by a so-called Mueller matrix.
In each of the above embodiments, the exposure apparatus 100 may be a scanning stepper that uses an immersion exposure method, or may be a dry scanning stepper or a stepper. Furthermore, the above-described embodiment is also used when the exposure apparatus uses an EUV exposure apparatus that uses EUV light (Extreme Ultraviolet Light) having a wavelength of 100 nm or less as exposure light, or an electron beam exposure apparatus that uses an electron beam as an exposure beam. Is applicable.

  In each of the above embodiments, the linearly polarized light obtained by converting the light from the light source unit 22 into linearly polarized light by the polarizer 26 is illuminated to the wafer. However, the light that illuminates the wafer is not linearly polarized light. It is also possible (see FIG. 1 (a)). For example, the wafer may be illuminated with circularly polarized light. In this case, for example, by providing a ¼ wavelength plate in addition to the polarizer 26, the light from the light source unit 22 is converted into circularly polarized light by the polarizer 26 and the ¼ wavelength plate to illuminate the wafer. Further, the wafer may be illuminated with elliptically polarized light other than circularly polarized light. A known configuration other than the above can be applied to the configuration for converting the light from the light source unit 22 into linearly polarized light or elliptically polarized light (elliptical polarized light including circularly polarized light). In addition to the light source that emits non-polarized light, such as a metal halide lamp or a mercury lamp, a light source that emits linearly polarized light or elliptically polarized light can also be used as the light source unit 22. In this case, the polarizer 26 can be omitted.

  Further, in each of the above embodiments, the quarter wavelength plate 33 is disposed on the optical path of the light reflected by the light receiving side concave mirror 31 of the light receiving system 30, but is not limited to this arrangement. For example, the quarter wavelength plate 33 may be disposed in the illumination system 20. Specifically, in the illumination system 20, the quarter-wave plate 33 may be disposed on the optical path of the light from the light guide fiber 24 that has passed through the polarizer 26. In this case, the quarter wavelength plate 33 is disposed on the optical path between the polarizer 26 and the illumination-side concave mirror 25.

In each of the above embodiments, the evaluation apparatus 1 is a part of the device manufacturing system DMS. However, the evaluation apparatus 1 may be used alone to evaluate the processing conditions from, for example, a pattern formed on a wafer. Good.
In addition, as shown in FIG. 13, a semiconductor device (not shown) includes a design process (step 221) for designing the function and performance of the device, and a mask manufacturing process for manufacturing a mask (reticle) based on the design process (step 221). Step 222), a substrate manufacturing process (Step 223) for manufacturing a wafer substrate from a silicon material or the like, a substrate processing process (Step 224) for forming a pattern on the wafer by the device manufacturing system DMS or a pattern forming method using the same. It is manufactured through an assembly process (step 225) including a dicing process for assembling a device, a bonding process, a packaging process, and the like, and an inspection process (step 226) for inspecting the device. In the substrate processing step (step 224), a coater / developer 200 applies a resist to the wafer, an exposure apparatus 100 exposes the mask pattern onto the wafer, and a coater / developer 200 develops the wafer. And an evaluation process (inspection process) for evaluating processing conditions such as film thickness conditions and / or exposure conditions using light from the wafer by the evaluation apparatus 1.

In such a device manufacturing method, the processing conditions are evaluated using the evaluation apparatus 1 described above, and the processing conditions are corrected based on the evaluation results, thereby improving the yield of the finally manufactured semiconductor. it can.
In the device manufacturing method of the present embodiment, the method of manufacturing a semiconductor device has been particularly described. However, the device manufacturing method of the present embodiment can be applied to a semiconductor material such as a liquid crystal panel or a magnetic disk in addition to a device using a semiconductor material. The present invention can also be applied to the manufacture of devices using other materials.

  Note that the requirements of the above-described embodiments can be combined as appropriate. Some components may not be used. In addition, as long as it is permitted by law, the disclosure of all published publications and US patents related to the inspection devices and inspection methods cited in the above embodiments and modifications are incorporated herein by reference.

  DMS ... Device manufacturing system, 1 ... Evaluation device, 5 ... Stage, 10 ... Wafer, 10a ... Conditional wafer, 12 ... Repeated pattern, 12a ... Hole pattern, 20 ... Illumination system, 30 ... Light receiving system, 35 ... Imaging unit, DESCRIPTION OF SYMBOLS 40 ... Image processing part, 50 ... Operation part, 60 ... Inspection part, 85 ... Memory | storage part, 100 ... Exposure apparatus, 200 ... Coater / developer

Claims (20)

In the evaluation method for evaluating the processing conditions of the evaluation target pattern formed under the predetermined processing conditions,
Irradiating the surface of the evaluation target substrate on which the evaluation target pattern is formed with polarized light;
Receiving diffracted light other than zero-order light emitted from the surface by irradiation of the polarized light, and detecting an amount defining a polarization state of the received diffracted light;
Evaluating the processing conditions when the evaluation target pattern is formed based on an amount defining the polarization state of the detected diffracted light;
Evaluation method including The processing conditions observed including a first processing condition and the second processing condition,
Detecting an amount that defines the polarization state of the diffracted light,
Under the first evaluation condition and the second evaluation condition, at least one of the incident angle of the polarized light irradiated on the surface, the wavelength of the polarized light, and the order of the diffracted light emitted from the surface is different from each other. Detecting an amount defining the polarization state of the diffracted light,
Evaluating the processing conditions when forming the evaluation target pattern,
The first processing condition is evaluated based on an amount defining the polarization state of the diffracted light detected under the first evaluation condition, and the diffracted light detected under the second evaluation condition The evaluation method according to claim 1, further comprising: evaluating the second processing condition based on an amount that defines the polarization state . The pattern to be evaluated formed on the surface is formed through a lithography process including thin film formation by a thin film forming apparatus, exposure by an exposure apparatus, and etching by an etching apparatus,
The first processing condition and the second processing condition are two conditions among a film forming condition of the thin film by the thin film forming apparatus, an exposure amount and a focus state in the exposure apparatus, and an etching condition in the etching apparatus. The evaluation method according to claim 2. Evaluating the processing conditions when forming the evaluation target pattern,
Reference data including information on the relationship between the amount of polarization of the diffracted light emitted from the substrate on which the pattern is formed on the surface under the known processing conditions and the known processing conditions, and emission from the evaluation target substrate 4. The evaluation method according to claim 2, further comprising evaluating the processing condition of the pattern to be evaluated based on an amount defining the polarization state of the diffracted light.   The evaluation method according to claim 4, comprising storing the reference data.   The reference is based on an amount that illuminates a substrate having a pattern formed on the surface under known processing conditions with polarized light and defines the polarization state of the diffracted light detected from the diffracted light emitted from the surface of the substrate. The evaluation method according to claim 4, further comprising obtaining data. Each of the first evaluation condition and the second evaluation condition is at least one of an illumination condition for irradiating the surface of the substrate to be evaluated with the polarized light and a light receiving condition for receiving the diffracted light emitted from the surface. only including,
The first evaluation condition is such that a change in an amount that defines the polarization state of the diffracted light with respect to a change in the first processing condition is an amount that defines a polarization state of the diffracted light with respect to a change in the second processing condition. Is a condition that is greater than the change,
The second evaluation condition is such that a change in an amount that defines the polarization state of the diffracted light with respect to a change in the second processing condition is an amount that defines a polarization state of the diffracted light with respect to a change in the first processing condition. Is a condition that is greater than the change,
The evaluation method according to claim 2, further comprising obtaining the first evaluation condition and the second evaluation condition . The first evaluation condition and the second evaluation condition are: a first relative angle between a polarization direction of the polarized light irradiated on the surface of the evaluation target substrate and a periodic direction of the evaluation target pattern, and irradiation on the surface. A second relative angle between the polarization direction of the polarized light and the polarization direction of the polarization component to be detected among the diffracted light emitted from the surface, the incident angle of the polarized light irradiated on the surface, and the polarization The evaluation method according to claim 7, comprising at least one value of a wavelength of light and an order of the diffracted light emitted from the surface.   The evaluation method according to claim 1, wherein the amount defining the polarization state of the diffracted light includes at least one of a Stokes parameter or a Jones vector. Forming a pattern on the surface of the substrate;
Evaluating the processing conditions when the pattern is formed using the evaluation method according to claim 1;
Correcting the processing conditions for forming the pattern according to the evaluation result of the evaluation method. In the evaluation apparatus for evaluating the processing conditions of the evaluation target pattern formed under the predetermined processing conditions,
An illumination unit for irradiating light on the surface of the evaluation target substrate on which the evaluation target pattern is formed;
A detection unit for detecting light emitted from the surface by irradiation of the light from the illumination unit;
Based on the state of light detected by the detection unit, an evaluation unit that evaluates the processing conditions when the evaluation target pattern is formed;
With
The illumination unit irradiates the surface with polarized light,
The detection unit receives diffracted light other than zero-order light emitted from the surface irradiated with the polarized light, and detects an amount that defines a polarization state of the diffracted light;
The evaluation unit evaluates the processing condition when the evaluation target pattern is formed based on an amount that defines the polarization state of the diffracted light detected by the detection unit. The processing conditions observed including a first processing condition and the second processing condition,
The detection unit includes a first apparatus condition and a second condition in which at least one of an incident angle of the polarized light irradiated on the surface, a wavelength of the polarized light, and an order of the diffracted light emitted from the surface is different from each other. Under apparatus conditions, detect the amount that defines the polarization state of the diffracted light,
The evaluation unit evaluates the first processing condition based on an amount defining the polarization state of the diffracted light detected by the detection unit under the first device condition, and the second device condition The evaluation apparatus according to claim 11, wherein the second processing condition is evaluated based on an amount that defines the polarization state of the diffracted light detected by the detection unit under the condition . The pattern to be evaluated formed on the surface is formed through a lithography process including thin film formation by a thin film forming apparatus, exposure by an exposure apparatus, and etching by an etching apparatus,
The first processing condition and the second processing condition are two conditions among a film forming condition of the thin film by the thin film forming apparatus, an exposure amount and a focus state in the exposure apparatus, and an etching condition in the etching apparatus. The evaluation apparatus according to claim 12. The evaluation unit is
Reference data including information on the relationship between the amount of polarization of the diffracted light emitted from the substrate on which the pattern is formed on the surface under the known processing conditions and the known processing conditions, and emission from the evaluation target substrate The evaluation apparatus according to claim 12 or 13, wherein the processing condition of the pattern to be evaluated is evaluated based on an amount defining the polarization state of the diffracted light.   The evaluation apparatus according to claim 14, further comprising a storage unit that stores the reference data. The evaluation unit is
The reference is based on an amount that illuminates a substrate having a pattern formed on the surface under known processing conditions with polarized light and defines the polarization state of the diffracted light detected from the diffracted light emitted from the surface of the substrate. The evaluation device according to claim 14 or 15, wherein data is obtained. Each of the first device condition and the second device condition is at least one of an illumination condition for irradiating the surface of the evaluation target substrate with the polarized light and a light receiving condition for receiving the diffracted light emitted from the surface. only including,
The evaluation unit is
Change in the amount defining the polarization state of the diffracted light with respect to a change in the first processing condition is larger than the change in the amount defining the polarization state of the diffracted light with respect to a change in the second machining condition the first Equipment conditions and
Change in the amount defining the polarization state of the diffracted light with respect to a change in the second machining condition is greater than the change in the amount defining the polarization state of the diffracted light with respect to a change in the first machining condition and the second and device conditions, the evaluation device according to any one of claims 12 to 16 asking you to. The first device condition and the second device condition are respectively a first relative angle between a polarization direction of the polarized light irradiated from the illumination unit to the surface and a periodic direction of the pattern, and from the illumination unit to the surface. A second relative angle between the polarization direction of the irradiated polarized light and the polarization direction of the polarization component detected by the detection unit of the diffracted light emitted from the surface, and the surface is irradiated from the illumination unit The evaluation apparatus according to claim 17, comprising at least one value among an incident angle of the polarized light, a wavelength of the polarized light irradiated from the illumination unit, and an order of the diffracted light detected by the detection unit.   The evaluation device according to any one of claims 11 to 18, wherein the amount defining the polarization state of the diffracted light includes at least one of a Stokes parameter or a Jones vector. A processing apparatus for forming a pattern on the surface of the substrate;
An evaluation apparatus according to any one of claims 11 to 19,
An exposure system that adjusts the processing apparatus in accordance with an evaluation result of the evaluation apparatus.

Images