JP2011009411A - Optical characteristic measuring method, exposure method, and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure optical characteristics of a projection optical system by obtaining the optical characteristics of the projection optical system based on an average value of detection results.SOLUTION: A method of measuring optical characteristics includes a step (S518) of changing stepwise an irradiation amount (dose) of illumination light irradiated onto a wafer provided on a side of an image plane via a measuring pattern on a reticle and the projection optical system. In addition, while a position of the wafer (focus position) with respect to an optical axis direction of the projection optical system is changed stepwise for each irradiation amount (S504), an image of the measuring pattern is transferred (S510) to respective internal different regions of a plurality of shot regions on the wafer by a step-and-scan method under such conditions that the irradiation amount and the focus position are common. The image of the measuring pattern formed in the plurality of partial regions inside each of the plurality of shot regions on the wafer is detected. The optical characteristics of the projection optical system are obtained based on the average value of the detection results in the plurality of shot regions for each condition in common.

Description

  The present invention relates to an optical property measurement method, an exposure method, and a device manufacturing method, and more specifically, an optical property measurement method for measuring an optical property of a projection optical system, an exposure method using the optical property measurement method, and the method The present invention relates to a device manufacturing method using an exposure method.

  Semiconductor elements (integrated circuits) and the like have been highly integrated year by year, and accordingly, a projection apparatus such as a stepper, which is a manufacturing apparatus for semiconductor elements, has been required to have higher resolution. It is also important to improve the overlay accuracy of the pattern after the next layer on the pattern already formed on the object to be exposed. As a premise, it is necessary to accurately measure and evaluate the optical characteristics (including imaging characteristics) of the projection optical system, and to improve the optical characteristics of the projection optical system based on the evaluation results (including adjustment). become.

  Accurate measurement of the optical characteristics of the projection optical system, for example, the image plane (curvature), is based on the premise that the best focus position at each evaluation point (measurement point) in the field of view can be accurately measured.

  As an example of a method for measuring the best focus position of a projection optical system, for example, a method disclosed in Patent Document 1 is known. In this method, exposure is performed using a reticle on which a predetermined pattern (for example, a line and space pattern) is formed as a test pattern, and the test pattern is applied to a test wafer at a plurality of positions in the optical axis direction of the projection optical system. Transcript. A resist image (transferred pattern image) obtained by developing the test wafer is picked up by, for example, an imaging alignment sensor provided in the exposure apparatus, and the contrast of the test pattern image obtained from the picked-up data The best focus position is obtained based on the relationship between the value (for example, the dispersion of the luminance value of the pixel) and the wafer position in the optical axis direction of the projection optical system. For this reason, this method is also called a contrast focus method.

  However, the best focus position obtained by the above-mentioned contrast focus method is easily influenced by the exposure conditions of the test pattern, particularly the amount of energy (dose amount) given to the wafer, and is particularly used for the manufacture of the most advanced devices. In the apparatus (projection optical system), it has recently been found that the best focus position obtained by the contrast focus method is more sensitive to the dose.

  In the conventional contrast / focus method, only one test pattern image with the same exposure condition, that is, the same dose and the same focus position is formed on the wafer for the same evaluation point. Measurement of the best focus position is affected by the error.

US Patent Application Publication No. 2004/0179190

  The present invention has been made under the circumstances described above. From the first viewpoint, the projection optical system projects an image of a pattern arranged on the first surface onto an object arranged on the second surface side. An optical property measurement method for measuring an optical property of a system, which is irradiated onto an object arranged on the second surface side through a measurement pattern arranged on the first surface and the projection optical system. The amount of energy beam and the projection optics are changed stepwise while changing the position of the object with respect to the optical axis direction of the projection optical system stepwise. Repeatedly transferring the image of the measurement pattern sequentially to different partial areas inside each of the plurality of partitioned areas on the object under the condition that the position of the object in the optical axis direction of the system is common. That; As a result, an image of the measurement pattern formed in a plurality of partial areas inside each of the plurality of partitioned areas on the object is detected, and the average of the detection results in the plurality of partitioned areas for each of the common conditions Determining an optical characteristic of the projection optical system based on a value; and an optical characteristic measuring method including:

  According to this, since the optical characteristic of the projection optical system is obtained based on the average value of the detection results in the plurality of partitioned regions for each common condition, the measurement pattern image detection result is obtained by the averaging effect. Random error components (including those caused by errors in the amount of energy beam irradiated onto the object) are reduced, and the optical characteristics of the projection optical system can be measured with high measurement stability.

  From a second viewpoint, the present invention uses the optical characteristic measurement method of the present invention to project an image of a pattern arranged on the first surface onto an object arranged on the second surface side. Measuring the optical characteristics of the system; taking into account the measurement results of the optical characteristics, adjusting at least one of the optical characteristics of the projection optical system and the position of the object with respect to the optical axis direction of the projection optical system; Projecting an image of the pattern onto the object disposed on the second surface side through the projection optical system, and exposing the object.

  This makes it possible to form a pattern image on the object with high accuracy, that is, to expose the object with high accuracy.

  From a third aspect, the present invention is a device manufacturing method including: forming a pattern on an object using the exposure method of the present invention; and processing the object on which the pattern is formed. .

It is a figure which shows schematically the structure of the exposure apparatus which concerns on one Embodiment. 2A and 2B are diagrams showing measurement reticles R _TH and R _TV , respectively. It is a flowchart which simplifies and shows the processing algorithm of CPU in the main controller regarding the measuring method of the optical characteristic of the projection optical system in the exposure apparatus which concerns on this embodiment. It is a flowchart which shows the specific example of step 406 of FIG. It is a diagram showing a movement path of the exposure center at the time of exposure of the arrangement and step-and-scan method of the shot areas on wafer W _T. It is a diagram showing one shot area on the wafer W _T that evaluation point corresponding region is formed. It is a figure for demonstrating an evaluation score corresponding | compatible area | region. It is a figure which shows an example of the data for every dose amount which plotted the contrast value with respect to the focus position.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of an exposure apparatus 100 suitable for carrying out the optical characteristic measuring method of the present invention. The exposure apparatus 100 is a step-and-scan reduction projection exposure apparatus (a so-called scanning stepper (also referred to as a scanner)).

  The exposure apparatus 100 projects an image of the pattern formed on the illumination system IOP, the reticle stage RST holding the reticle R, and the reticle R onto the wafer W coated with a sensitive agent (here, a positive resist). A unit PU, a wafer stage WST that holds the wafer W and moves in the XY plane, a drive system 22 that drives the wafer stage WST, and a control system thereof are provided. The control system is mainly composed of a main controller 28 including a microcomputer (or a workstation) that performs overall control of the entire apparatus.

  The illumination system IOP includes, for example, a light source composed of an ArF excimer laser (output wavelength 193 nm) (or KrF excimer laser (output wavelength 248 nm)), and an illumination optical system connected to the light source via a light transmission optical system. . Illumination optical systems include, for example, an illuminance uniformizing optical system including an optical integrator, a beam splitter, an integrator sensor, a reticle blind, etc. (all of which are not disclosed), as disclosed in, for example, US Patent Application Publication No. 2003/0025890. Included). This illumination optical system shapes the laser beam emitted from the light source, and the shaped laser beam (hereinafter also referred to as illumination light) IL causes the X axis direction (the direction perpendicular to the paper surface in FIG. 1) on the reticle R. A slit-like illumination area that is elongated is illuminated with substantially uniform illuminance. Here, the illuminance (intensity) of the illumination light IL is measured by the integrator sensor, and the measurement result is sent to the main controller 28. The relationship between the output of the integrator sensor and the illuminance of the illumination light IL on the image plane is obtained in advance and stored in a memory inside the main controller 28.

  Reticle stage RST is arranged below illumination system IOP in FIG. Reticle R is placed on reticle stage RST. The reticle R is sucked and held on the reticle stage RST via a vacuum chuck or the like (not shown). Reticle stage RST can be finely driven in a horizontal plane (XY plane) by a reticle stage drive system (not shown), and has a predetermined stroke in the scanning direction (here, the Y axis direction which is the horizontal direction in FIG. 1). Scanned in range. Position information of the reticle stage RST is measured by the laser interferometer 14 via the movable mirror 12 fixed to the end thereof, and the measurement value of the laser interferometer 14 is supplied to the main controller 28. Instead of the movable mirror 12, the end surface of the reticle stage RST may be mirror-finished to form a reflective surface (corresponding to the reflective surface of the movable mirror 12).

  Projection unit PU is arranged below reticle stage RST in FIG. The projection unit PU includes a lens barrel 40 and a plurality of optical elements held in a predetermined positional relationship within the lens barrel 40, and a pattern of a first surface (object surface) is formed on a second surface (imaging surface). Projection optical system PL for projecting onto the projector. Here, as the projection optical system PL, a bilateral telecentric reduction system is used, and a refractive optical system including a plurality of lens elements (not shown) arranged in a direction parallel to the optical axis AXp (Z-axis direction) is used. It has been. A plurality of specific lens elements are movable, and are controlled by an imaging characteristic correction controller (not shown) based on a command from the main controller 28, whereby the optical characteristics (imaging characteristics) of the projection optical system PL are controlled. Characteristics), for example, magnification, distortion, coma aberration, field curvature, and the like are adjusted.

  The projection magnification of the projection optical system PL is ¼ as an example. For this reason, when the reticle R is illuminated with uniform illumination by the illumination light IL as described above, the pattern of the reticle R in the illumination area is reduced by the projection optical system PL and projected onto the wafer W. A reduced image of the pattern is formed in a part of the shot area. At this time, the projection optical system PL forms a reduced image in a part of its field of view (that is, a slit-shaped region (exposure region) conjugate with the illumination region with respect to the projection optical system PL). Note that the imaging characteristic correction controller described above adjusts at least one optical element (lens) of the projection optical system PL in order to adjust the optical characteristics of the projection optical system PL, that is, the imaging state of the pattern image on the wafer W. However, instead of or in combination with it, the characteristics of the illumination light IL (for example, the center wavelength, spectrum width, etc.) can be changed by controlling the light source, and the optical axis of the projection optical system PL. At least one of movement of the wafer W in the Z-axis direction parallel to AXp (and inclination with respect to the XY plane) may be performed.

  Wafer stage WST is arranged below projection optical system PL (on the −Z side). Wafer stage WST is mounted on XY stage 20 that moves along a XY plane on a base plate (not shown), and wafer table 18 that is mounted on XY stage 20 and holds wafer W by vacuum suction or the like via a wafer holder (not shown). Including.

  The wafer table 18 finely drives the wafer holder holding the wafer W in the Z-axis direction and the tilt directions with respect to the XY plane (the rotation direction about the X axis (θx direction) and the rotation direction about the Y axis (θy direction)). , Also called Z-tilt stage. The position information of the wafer table 18 is measured by a laser interferometer 26 that irradiates the movable mirror 24 with a laser beam (measurement beam) and receives reflected light from the movable mirror 24. The measurement information of the laser interferometer 26 is supplied to the main controller 28, and the main controller 28 based on the measurement information of the laser interferometer 26, the position information of the wafer table 18 in the direction of 5 degrees of freedom, that is, the X-axis direction. Position information in the Y-axis direction and rotation information (yawing (θz rotation that is rotation around the Z axis)), pitching (θx rotation that is rotation around the X axis), rolling (θy rotation that is rotation around the Y axis) Calculated). Instead of the movable mirror 24, the end surface (side surface) of the wafer table 18 may be mirror-finished to form a reflective surface (corresponding to the reflective surface of the movable mirror 24).

  Further, the position of the surface of the wafer W in the Z-axis direction and the amount of inclination with respect to the XY plane are, for example, an oblique incidence method having a light transmission system 50a and a light reception system 50b disclosed in US Pat. No. 5,448,332. It is measured by a focus sensor AFS comprising a multipoint focal position detection system. The measurement value of the focus sensor AFS is also supplied to the main controller 28.

  The main controller 28 controls the XY stage 20 via the drive system 22 based on the position information in the five-degree-of-freedom direction described above to thereby position the wafer W in the XY plane (including rotation in the θz direction). To control. The main controller 28 controls the position of the wafer W in the Z-axis direction and the inclination with respect to the XY plane by controlling the wafer table 18 via the drive system 22 based on the measurement value of the focus sensor AFS.

  Further, a reference plate FP is fixed on the wafer table 18 so that the surface thereof is the same height as the surface of the wafer W. On the surface of the reference plate FP, a reference mark used for baseline measurement of the alignment system AS described below is formed.

  In the present embodiment, an off-axis alignment system AS is provided on the side surface of the projection optical system PL. The alignment system AS includes, for example, an image processing type alignment sensor called an FIA (Field Image Alignment) system, and uses a reference mark formed on the reference plate FP and an alignment mark formed on the wafer W as detection targets. The position information of the detection target mark in the two-dimensional direction (X-axis direction and Y-axis direction) is measured.

  Here, the FIA system is a sensor that measures a mark position by illuminating a mark with broadband light such as a halogen lamp and performing image processing on the mark image. The alignment system AS includes, for example, an alignment sensor that irradiates the target mark with coherent detection light and detects the diffracted light generated from the target mark by interfering with (or in place of) the FIA system. May be.

  The alignment control device 16 performs A / D conversion on the output signal DS from the alignment system AS, performs arithmetic processing on the converted signal, and detects a mark position. The detection result is supplied from the alignment controller 16 to the main controller 28.

  Further, in the exposure apparatus 100 of this embodiment, although not shown, light having an exposure wavelength disclosed in, for example, US Pat. No. 5,646,413 is used above the reticle R. A pair of reticle alignment systems of the TTR (Through The Reticle) method is provided, and detection signals of the reticle alignment system are supplied to the main controller 28 via the alignment controller 16.

  In addition, an illuminance monitor and an illuminance unevenness on the wafer stage WST (wafer table 18) for measuring the illuminance and the illuminance distribution (unevenness) on the surface of the wafer W onto which the illumination light IL is projected through the projection optical system PL. A sensor (not shown) or the like is provided.

In the present embodiment, two reticles R _TH and R _TV are used to measure the optical characteristics of the projection optical system PL. FIG. 2A shows one of the reticles R _TH . FIG. 2A is a plan view of reticle _RTH viewed from the pattern surface side (lower surface side in FIG. 1). As shown in FIG. 2A, the reticle R _TH is composed of a rectangular (exactly square) glass substrate 42, and the pattern surface has a substantially rectangular pattern area PA defined by a light shielding band (not shown). In this example (example in FIG. 2A), almost the entire pattern area PA is a light-shielding portion by a light-shielding member such as chromium. The center of the pattern area PA (the center of the reticle R _TH here (matching reticle center)), and a total of 5 points of four corners of the portion of the inner pattern area PA, a predetermined width, for example, one side of the square 27μm aperture pattern ( Transmission regions) AP _{1 to} AP ₅ are formed, and measurement patterns (hereinafter abbreviated as patterns as appropriate) MP _H1 to MP _H5 are formed in the opening patterns AP _{1 to} AP ₅ , respectively. In this example, almost the entire pattern area PA is used as the light shielding part, but the pattern area PA may be used as the light transmitting part. In this case, both ends in the X-axis direction of the slit-shaped illumination area are defined by the above-described light-shielding bands. Therefore, light-shielding portions having predetermined widths (for example, the same width as the light-shielding bands) are provided at both ends in the Y-axis direction. May be.

Each of the patterns MP _Hn (n = 1 to 5) has, for example, a predetermined line width, for example, 0.6 μm, and a predetermined length, for example, three (or five) line patterns of about 9 μm have a predetermined pitch, For example, it is constituted by a multi-bar pattern arranged in the X-axis direction at 2.0 μm. Hereinafter, the pattern MP _Hn is also referred to as an H line pattern for convenience.

  Further, a pair of reticle alignment marks RM1 and RM2 are formed on both sides in the X-axis direction of the pattern area PA passing through the above-described reticle center (see FIG. 2A).

FIG. 2B shows another reticle R _TV . FIG. 2B is a plan view of reticle R _TV viewed from the pattern surface side (lower surface side in FIG. 1). As shown in FIG. 2B, the reticle R _TV has the glass substrate 42 as in the above-described reticle R _TH and has the above-described pattern region PA defined by a light shielding band (not shown) on its pattern surface. A pattern area PA ′ having the same shape and size as that of the pattern area PA ′ is formed. However, in this example, measurement patterns (hereinafter abbreviated as patterns as appropriate) MP _V1 to MP _V5 are formed inside the opening patterns AP _{1 to} AP ₅ , respectively. Each of the patterns MP _{V1 to} MP _V5 is configured by a _multibar pattern similar to the pattern MP _Hn except that the arrangement direction (periodic direction) is the Y-axis direction. Hereinafter, the pattern MP _Vn is also referred to as a V-line pattern for convenience. Note that the entire surface of the pattern area PA ′ may be a light transmission portion.

Next, regarding the method of measuring the optical characteristics of the projection optical system PL in the exposure apparatus 100 of the present embodiment, along with the flowchart of FIG. This will be described with reference to the drawings. In the following, for convenience of explanation, the term and sign of the measurement pattern (or pattern) MP _n are used, which means the pattern MP _Hn when the reticle R _TH is being used unless otherwise specified. When the reticle R _TV is in use, it means the pattern MP _Vn . Further, the description regarding the main control device 28 is omitted unless particularly necessary.

First, in step 402 in FIG. 3, the wafer is exchanged. Specifically, after unloading a wafer from the wafer table 18 via a wafer unloader (not shown), a test wafer (hereinafter simply referred to as a wafer) W _T (see FIG. 5) is transferred to the wafer via a wafer loader (not shown). Load on table 18. It should be noted that, when there is no wafer on the wafer table 18 performs only the loading of the wafer W _T.

  Next, in step 404, predetermined preparatory work such as reticle replacement and alignment of the reticle with respect to the projection optical system PL is performed.

Specifically, first, exchanging the reticle and the 1st reticle R _TH on the reticle stage RST via a reticle exchange mechanism (not shown). When there is no reticle on the reticle stage RST, simply loads the reticle R _TH.

Next, a pair of reticle alignment marks RM1 and RM2 of a pair of reference marks (not shown) on the reference plate FP and a reticle (reticle R _{TH in} this case) on the reticle stage RST by the above-described reticle alignment system (not shown). , Reticle stage RST and wafer stage WST are moved based on the measurement values of laser interferometers 14 and 26, respectively. Then, the position (including rotation) of reticle stage RST in the XY plane is adjusted based on the detection result of the above-described reticle alignment system.

In the present embodiment, scanning exposure is performed using the reticles R _TH and R _TV, and a dynamic optical characteristic of the projection optical system PL, for example, a dynamic image plane is obtained, so that the measurement pattern MP _n is obtained via the projection optical system PL. The position in the exposure area where the projection image (pattern image) is generated becomes an evaluation point at which the optical characteristic (for example, focus) of the projection optical system PL should be measured. Although the number of evaluation points is actually more than five, in the present embodiment, for the convenience of explanation, a total of five evaluation points (measurements) at the center and four corners of the exposure area (corresponding to the pattern area PA) are used. (Corresponding to the position of the pattern MP _n for use) is set. However, the number of evaluation points (measurement pattern MP _n ) may be at least one.

  When the predetermined preparation work is completed in this way, the process proceeds to the next step 406 (exposure processing subroutine).

In this subroutine, first, as shown in FIG. 4, in step 502, the amount per unit area of illumination light IL irradiated on wafer W _T (exposure amount), i.e. the dose of the target (target dose call) to initialize the _{P j.} That is, the initial value “1” is set to the counter j, and the target dose amount P _j is set to P ₁ (j ← 1). In the present embodiment, the counter j, together with the setting of the target dose, also used to set the movement target position of the X-axis direction of the wafer W _T during exposure. In the present embodiment, for example, the wafer W about the optimal dose to be expected from the sensitivity characteristics of been sensitive adhesive coated on a _T (resist), N as N Street (an example in ΔP increments from P ₁ to P _N The target dose amount (P _j = P _{1 to} P ₂₃ ) is set.

In the next step 503, the dose amount (energy amount per unit area) of the illumination light IL on the wafer surface (substantially coincides with the image plane of the projection optical system PL) is stabilized. Specifically, wafer stage WST (XY stage 20) is driven via drive system 22 while monitoring the measurement value of laser interferometer 26, and wafer stage WST (wafer table 18) is directly below projection optical system PL. The upper illuminance monitor is positioned, and emission of laser light (pulse light) from the light source is started. Then, the output of the illuminance monitor (the illuminance of the illumination light IL) is monitored to wait until the intensity (light quantity) of the illumination light IL is sufficiently stabilized. This is immediately after especially the laser light emission start, with the oscillation state of the laser is unstable, the transmittance of the illumination light IL is varied by the projection optical system PL absorbs illumination light IL, the wafer W _T This is because, while the dose of the illumination light IL applied to the light source does not become constant, the transmittance becomes constant after reaching a predetermined saturation value due to the absorption of the constant amount of illumination light IL.

  Then, when it is confirmed that the dose amount on the wafer surface is stable, the routine proceeds to step 504.

In the next step 504, the target focus position of the wafer W _T (Z-axis direction position) (hereinafter, referred to as a target focus position) to initialize the Z _i. That is, by setting the initial value "1" to the counter i sets the target focus position Z _i of the wafer W _T to Z ₁ (i ← 1). In the present embodiment, the counter i, together with the setting of the target focus position of the wafer W _T, is also used to set the movement target position in the Y-axis direction of the wafer W _T during exposure. In the present embodiment, for example, M (in the example, M = 13) target focus in increments of ΔZ from Z ₁ to Z _M centering on a known best focus position (design value, etc.) relating to the projection optical system PL. The position (Z _i = Z _{1 to} Z ₁₃ ) is set.

In the present embodiment, as described below, while changing the position and the dose of illumination light IL irradiated on wafer W _T of the wafer W _T to an optical axis of the projection optical system PL respectively, patterns MP _n ( n = 1 to 5) exposure for transferring onto the wafer _{W T} to is performed. Further, in the present embodiment, a series of path to the end point E from the starting point B shown in FIG. 5 (hereinafter, referred to as route BE) exposed around the upper wafer W _T along the (center of the aforementioned exposure region In this embodiment, the exposure is performed once (exposure under one exposure condition determined according to the dose amount and the focus position) so that the optical axis AX of the projection optical system PL moves. the movement path of the wafer W _T is, are determined. In practice, although the wafer with respect to the exposure center of the fixed and the route BE is to move along the reverse path, in consideration of the comprehensibility of FIG. 5 shown and described, the wafer W _T The exposure center is shown to move along the path BE. Route BE is the same as when sequentially transferred by a so-called full alternately scan exposure patterns MP _n shot area (divided _area) S 1 _{to S 26,} a moving path of the exposure center to wafer _{W T.}

In the next step 506, by driving the wafer stage WST (XY stage 20) via the drive system 22 while monitoring the measurement values of laser interferometer 26, the wafer W _T, corresponding to the starting point of the route BE described above , the scanning start position for exposure of the shot area _{S 1} on the wafer _{W T} (for _{convenience, (X} i, and _{Y j))} is positioned. In this case, since i = 1, j = 1, the wafer _{W T} is positioned at the scanning start position (X1, Y1).

If the wafer W _T is positioned at the scanning start position, the reticle R _{TH (reticle} stage RST) during the scanning exposure will be described later with wafer W _{T (wafer} stage WST) and the relative scanning in the scanning direction (Y axis direction) Once, the wafer _W divided area (partial area) of the evaluation point corresponding area DB ₃ on _{T DA i} to the center of exposure is shown in Figure _6, the center of _j (here _{DA 1, 1} (see FIG. 6)) Will pass. The evaluation point corresponding area will be described later.

In the next step 508, the wafer table 18 while monitoring the measurement values from the focus sensor AFS and finely driven in the Z-axis direction and the tilt direction, the wafer W _T in the Z-axis direction position target focus position Z that is set to Set to _i (Z _{1 in} this case).

In the next step 510, while moving the wafer W _T along a path corresponding to the path BE, performs exposure by the step-and-scan method. Specifically, as through a drive system 22 while monitoring the measurement values of laser interferometer 26, the exposure center is moved on the wafer W _T in the direction of the arrow along the path BE to the end point E from the starting point B, wafer _{W T} to drive the wafer table 18 which is placed (wafer stage WST). In this case, when the exposure center moves in a straight section (see FIG. 5) in the path BE, the wafer table 18 (wafer stage WST) and the reticle stage RST are synchronized at a constant speed in the scanning direction (Y-axis direction). drive (relative scanning), and via the projection optical system PL on a shot region _S k of illuminating the reticle _{R TH} on the pattern wafer _{W T} by the illumination light IL when moving the constant velocity synchronized (k = 1 to 26) And transcribe. That is, as in the case of transferring a device pattern to the shot area _S 1 _{to S 26} on full alternate scanning by the wafer _{W T,} the shot area _S and the scan exposure on _k, the wafer table between shot areas 18 (wafer stage WST) These stepping operations are alternately repeated. Thus, as shown FIG. 6, the wafer _W divided area _{DA i} evaluation point corresponding area DB _n of _T on the shot area _{S 1 ~S 26 (n = 1~5} ), j (DA here _1,1 ), The pattern MP _Hn (n = 1 to 5) is transferred under the same exposure conditions (focus position Z _i and dose amount P _j ).

During exposure of the above, the main controller 28, the target dose of the dose Q is set on the wafer W _T such that (in this case P _1), performs the exposure control. The dose amount Q can be adjusted by changing at least one of the energy amount per pulse (pulse energy amount) of the illumination light IL and the number of pulses of the illumination light IL irradiated onto the wafer. In the present embodiment, the pulse energy amount of the illumination light IL is set sufficiently small, that is, smaller than the pulse energy amount set at the time of normal device manufacture, and the number of pulses is changed with respect to the pulse energy amount, The exposure amount is controlled with higher accuracy than in normal device manufacturing. Here, since the illuminance monitor cannot be used during exposure, the dose control is performed on the image plane based on the relationship between the output of the integrator sensor and the illuminance of the illumination light IL on the image plane. The transmittance is calculated by calculating the illuminance of the illumination light IL and substituting the amount of absorption of the illumination light of the projection optical system obtained from the output of the integrator sensor into the calculation formula for predicting the temporal change of the transmittance of the projection optical system. The dose is managed and adjusted by changing the number of pulses of the illumination light IL irradiated on the wafer in consideration of the calculated illuminance and transmittance of the illumination light IL. . The main control unit 28, each time the exposure of each divided area _{DA i, j} of evaluation point corresponding area DB _n shot area _{S k} shown in FIG. 6 (n = 1~5), the dose _{Q kij} Simultaneously with the control, the dose amount Q _kij (or the pulse energy amount and the pulse number) at the time of exposure is recorded in the exposure history.

In the next step 512, check the target focus position of the wafer W _T (the value of the counter i), the exposure of the predetermined range (namely from the target focus position Z ₁ Z _M) to determine whether or not it is completed. Here, since only the exposure of the first target focus position Z ₁ is completed, the process proceeds to step 514, the value of the counter i is incremented by 1 (i ← i + 1) with the target focus position of the wafer W _T Z _{i + 1} Change to (here Z ₂ ). After changing the target focus position, the process returns to step 506. Then, the processing (including judgment) of steps 506, 508, 510, 512, and 514 is repeated until the judgment in step 512 is affirmed.

However, when the above process is repeated, every time the value of i is incremented by 1, the main controller 28 shifts in the −Y direction by a predetermined step pitch ΔY from the scanning start position at the previous exposure in step 506. as the position _{(X j, Y i (=} Y i-1 -ΔY)) a target position, sequentially performs positioning of the wafer _{W T.} Thus, the value of i for each incremented by one, path BE on the wafer W _T of the center of exposure becomes the sequentially shifted by + Y direction by a predetermined step pitch [Delta] Y. The step pitch ΔY is determined to be equal to the width of the partition area DA _{i, j in} the Y-axis direction as shown in FIG. 7 by enlarging the evaluation point corresponding area DB _n .

Processing of steps 506,508,510,512,514 by repeated (including judgment), the evaluation point in the shot area _S 1 _{to S 26} on wafer _{W T} corresponding area DB _n (n = 1 to 5) The image of the measurement pattern MP _n (in this case, the pattern MP _Hn ) is transferred to each of the divided areas DA _{i, 1} (i = 2 to M).

On the other hand, when the exposure to the partition area DAM _{, 1} is completed and the determination in step 512 is affirmed, the process proceeds to step 516, where the target dose (the value of the counter j) is confirmed, and a predetermined range (that is, the target) exposure for P _N) from a dose P ₁ determines whether or not it is completed. Here, since the target dose amount set at that time is P ₁ , the determination in this step 516 is denied, and the routine proceeds to step 518.

In step 518, the value of the counter j is incremented by 1 (j ← j + 1), and the target dose is changed to P _{j + 1} (here, P ₂ ). After changing the target dose amount, the process returns to step 504. Then, main controller 28 repeats the processing (including determination) in steps 504, (506, 508, 510, 512, 514), 516, 518 until the determination in step 516 is affirmed.

The main controller 28 initializes the value of i to 1 in step 504 every time the value of the counter j is incremented by 1 when the processing is repeated, and in step 506, the target position in the Y-axis direction is Y _1. Thus, with respect to the X-axis direction, a position (X _j (= X _j−1 −ΔX), Y ₁ ) shifted in the −X direction by a predetermined step pitch ΔX from the scanning start position at the previous exposure is set as the target position. , in order to position the wafer _{W T.} Thus, the value of i for each incremented by one, path BE on the wafer W _T of the exposure center and returned to the initial position in the Y-axis direction, and sequentially shifted to the predetermined step pitch ΔX only the + X direction Become. As shown in FIG. 7, the step pitch ΔX is set equal to the width of the partition area DA _{i, j in} the X-axis direction.

The above step 504, (506,508,510,512,514), by repeating the processing of 516 and 518 (including the judgment), the evaluation point in the shot area _S 1 _{to S 26} on wafer _{W T} corresponding area DB An image of the measurement pattern MP _n (in this case, the pattern MP _Hn ) is transferred to each of the divided areas DA _{i, j} (i = 1 to M, j = 2 to N) of _n (n = 1 to 5).

When the exposure for the target dose amount (P _{1 to} P _N ) in the predetermined range is completed in this way, the determination in step 516 is affirmed, the processing of this subroutine is terminated, and FIG. 3 (main routine) The process proceeds to step 408 (returns).

The process of step 406, once the exposure (13 × 23 = 299 as an example) M × N for each shot area _{S k} on wafer _{W T} is performed, the result, in each shot area _{S k} of the wafer _{W T} As shown in FIG. 5, five regions corresponding to each evaluation point are formed. In these five areas, that is, the above-described evaluation point corresponding areas DB _{1 to} DB ₅ (see FIGS. 6 and 7), N × M (23 × 13 = 299 as an example) with different exposure conditions are used. A transfer image (latent image) of the pattern MP _n (in this case, the pattern MP _Hn ) is formed. The evaluation point corresponding region DB _n (n = 1 to 5) corresponds to a plurality of evaluation points that should evaluate the optical characteristics (in this case, dynamic optical characteristics) of the projection optical system PL in the exposure area.

7, each evaluation point corresponding area DB _n on wafer W _T is shown enlarged. In this embodiment, M × N (= 13 × 23 = 299) virtual partition areas DA _{i, j} (i = 1 to M, arranged in a matrix of M rows and N columns (13 rows and 23 columns). j = 1 to n) to the pattern MP _n is transferred respectively formed the patterns MP _n is M × been transferred each of the n divided areas _{DA i,} evaluation point corresponding area DB _n consisting of _j is on the wafer _{W T} Is done. As shown in FIG. 7, the virtual partition areas DA _{i, j} are arranged so that the + X direction is the row direction (increase direction of j) and the + Y direction is the column direction (increase direction of i). ing.

In practice, as described above, pieces of divided areas (13 × 23 = 299 as an example) M × N to transfer image (latent image) is formed of a measurement pattern MP _n on wafer W _T is in the formed step, but than the evaluation point corresponding area DB _n are formed, if in the above description, for ease of explanation, evaluation point corresponding area DB _n is on the advance wafer W _T Such an explanation method is adopted.

In step 408 of FIG. 3, the wafer W _T, and unloaded from above the wafer table 18 via a wafer unloader (not shown), via wafer transport system (not shown), in-line connected to the coater to exposure apparatus 100 -Transport to a developer (not shown).

After transfer of the wafer W _T for coater developer, development of wafer W _T waits for the end proceeds to step 410. During the waiting time in step 410, development of the wafer W _T is performed by the coater developer. By the end of this development, in each shot area S _k on wafer W _T, the resist image of the evaluation points as shown in FIG 6 corresponding area DB _{n (n} = 1~5) are formed, the resist image is a sample for measuring the optical characteristic in the step 418 that the wafer W _T is described later formed.

In the wait state of step 410, when confirming that the development of wafer W _T is completed by a notice from the control system of the coater developer (not shown), the process proceeds to step 412.

In step 412, instructs the wafer loader (not shown), similar to step 402 described above to load the developed wafer W _T on the wafer table 18.

In the next step 414, using the developed wafer W _T, in order to obtain basic data that can be used to determine the optimal dose and optical properties, performs predetermined image processing.

Specifically, the main controller 28, for each evaluation point corresponding areas _DB 1 to DB ₅ in the shot area _S 1 _{to S 26} on wafer _{W T,} following a. ~ D. Perform the process.

a. First, a resist image of evaluation point corresponding area DB _n in each shot area S _k on wafer W _T, and imaged using the alignment system AS (FIA system), it captures the captured data. The alignment system AS divides the resist image into pixel units of the image sensor (CCD or the like) and supplies the density of the resist image corresponding to each pixel to the main controller 28 as 8-bit digital data (pixel data), for example. That is, the imaging data is composed of a plurality of pixel data. In this case, it is assumed that the pixel data value increases as the density of the resist image increases (closer to black). In this case, it is assumed that an area including N × M partition areas DA _{i, j} in the evaluation point corresponding area DB _n can be simultaneously (collectively) imaged by the alignment system AS.

b. Next, the outer edge of the evaluation point corresponding region DB _n is detected by performing image processing on the imaging data by a method disclosed in, for example, US Patent Application Publication No. 2004/0179190.

c. Next, the outer edge of the evaluation point corresponding area DB _n detected above, that is, the inside of the rectangular frame line is equally divided by using the number M in the vertical direction and the number N in the horizontal direction of the known partition areas, The partition areas DA _{1,1 to} DAM _{, N} are obtained. That is, each partition area DA _{i, j} (position information) is obtained using the outer edge as a reference.

d. Then, the partitioned regions DA _i of each evaluation point corresponding area DB _n in each shot area _{S k, j (i = 1~M} , j = 1~N) to form resist images each brightness information, for example the contrast The value E _{kn, ij} (also expressed as E _{i, j} for simplicity) is calculated, and the calculation result is stored in the memory. Here, the contrast value E _{i, j} is given by, for example, the variance (or standard deviation) of pixel data. Alternatively, the contrast value E _{i, j} is given as E _{i, j} = (L _MAX −L _MIN ) / (L _MAX + L _MIN ) from the maximum L _MAX and the minimum L _MIN of the pixel data values.

A. ~ D. Performs processing for all evaluation points corresponding area DB _n of all the shot area _{S k,} determined shot area _{S k,} evaluation point corresponding area DB _n, divided area DA _i, the contrast value _{E kn} for each _j, a _ij .

When the above image processing is completed, the process proceeds to the next step 416, and it is determined whether or not the processing using the reticle R _TV is completed. In this case, since the process using the reticle R _TV has not been performed yet, the determination in step 416 is denied and the process returns to step 402.

In step 402, the wafer is changed in the same manner as described above, and then in step 404, the reticle is changed. At this time, reticle R _TV is loaded on reticle stage RST instead of reticle R _TH . Further, preparatory work such as alignment of the reticle R _TV after the replacement with respect to the projection optical system PL is performed.

Thereafter, the processing using the reticle R _TV (the processing in steps 406 to 414) is performed in the same manner as described above.

In step 416, the main controller 28 determines again whether or not the processing using the reticle R _TV has been completed. In this case, since the process using the reticle R _TV has been completed, the determination here is affirmed and the routine proceeds to step 418.

  In step 418, the main controller 28 performs the following e. ~ G. The optimal dose amount is determined in accordance with the above procedure, and the best focus position and the like are obtained with respect to the determined optimal dose amount.

e. First, for each evaluation point corresponding area DB _n, (target) dose P _j and the type of measurement pattern (H line, V line) for each, each divided area DA i _calculated, the contrast value of _j E _{i, j} Is plotted on a graph in which the horizontal axis shown in FIG. 8 is the focus position Z _i and the vertical axis is the contrast value.

In more detail, in the present embodiment, the exposure amount by main controller 28 (the dose Q) but are accurately controlled, dose Q of illumination light IL on the actual wafer W _T is the target dose It does not necessarily match P _j . On the other hand, in the present embodiment, the measurement pattern MP _n is applied to all the plurality of shot regions S _k (k = 1 to 26) on the wafer W _T under the same exposure conditions (focus position Z _i and dose amount P _j. ). Therefore, main controller 28 uses previously determined in step 414, the partitioned regions DA _i of each evaluation point corresponding area DB _n in each shot area _{S k,} the contrast value of _{j E kn,} a _ij, common condition (the focus position, the dose) of the average value of the contrast values in the 26 shot areas _{S k} for each _{(ΣE k, ij / 26)} = aveE i, a _j, determined for each evaluation point corresponding area DB _n. The obtained average value aveE _{i, j} is plotted in the graph as the contrast value E _{i, j with} respect to the focus position Z _i . Contrast values E _{i, j} for the H and V lines are plotted in the same graph (see FIG. 8). The plot of the contrast value E _{i, j} is performed for each evaluation point corresponding region DB _n .

As can be seen from FIG. 8, the contrast value E _{i, j} is lower (higher) as the dose _Pj is higher (lower). Here, the contrast curve connecting the plot points with respect to the dose amount P _j in the optimal range (Opt. Dose) shows an ideal profile, that is, a mountain-shaped (convex) profile. Further, the optimum range (Opt.Dose) higher dose _{P j} (a dose _{P j} in the region Over Dose), the contrast curve indicates the profile of the mountain shape, the effective data is less. Further, the optimum range (Opt.Dose) lower dose _{P j} (a dose _{P j} in the region Under Dose), the lower the dose _{P j,} collapsed peak profile of the contrast curve, there is a dose _{P j} When the value is lower than the value, a valley-shaped (concave) profile is shown.

f. Next, for each evaluation point corresponding region DB _n , for each dose amount P _j and measurement pattern type (H line, V line), a contrast curve and / or each divided region DA _{i, j} (i = 1 to M, The optimum dose amount P _optn is obtained using the data of the contrast value E _{i, j} of the resist image formed at j = j). Here, the contrast curve shows an ideal profile at the optimum dose. Therefore, the main controller 28 gives, for example, an approximation function describing an ideal profile, performs least square fitting of the data of each contrast value E _{i, j} , and each contrast value from the curve (approximation function) after the fitting. The dose amount that minimizes the deviation (square error) of E _{i, j} is defined as the optimum dose amount P _optn . In addition, the main control device 28 determines the astigmatism (contrast for each of the V-line pattern and the H-line pattern, for example, when the deviation between the contrast curves for a plurality of doses is approximately the same. The dose amount P _j that minimizes the difference between the best focus positions obtained from the curve is the optimum dose amount P _optn .

Here, the main controller 28 confirms that the square error with respect to the contrast value E _{i, j} corresponding to the optimum dose amount P _optn is sufficiently small, and contrast value E _{i, j} that is remarkably far from the contrast curve, that is, Make sure there is no jump data. When there is jump data, it can be determined that the dose amount Q when the measurement pattern corresponding to the jump data is transferred to the partitioned area DA _ij is deviated from the target dose amount P _j . Therefore, the main controller 28 _replaces the jump data with the contrast value E _{kn, ij} corresponding to the dose amount Q _kij closest to the target dose amount P _j or uses the dose amount Q _kij by the method described _below . Te is corrected to a value corresponding to the target dose of P _j.

That is, the main controller 28 records the dose amount Q _kij (k = 1 to 26 (or pulse energy) recorded for each of the shot area S _k (k = 1 to 26) and the _divided areas DA _{i, j} included in the exposure history. The product of the quantity and the number of pulses)) is confirmed, and the contrast value E _{kn, ij} corresponding to the dose quantity Q _kij that is closest to the target dose quantity P _j is extracted therefrom. Then, the jump data is replaced with the contrast value E _{kn, ij} . Alternatively, instead of extracting the corresponding contrast value, the 26 contrast values E _{kn, ij} (k = 1 to 26) are weighted averaged using the dose amount Q _kij (k = 1 to 26), and the like. The contrast value E _{i, j} corresponding to the target dose amount P _j may be obtained.

In addition, when the relationship between the contrast value E and the dose amount Q is obtained in advance, the jump data is calculated using the relationship and the recorded dose amount Q _kij (k = 1 to 26). It is also possible to correct the contrast value E _{i, j} corresponding to the target dose amount P _j . Here, since the relationship between the contrast value E and the dose amount Q usually depends also on the focus Z, these three relationships may be obtained in a map format.

g. Next, the optical characteristic of the projection optical system PL, for example, the best focus position is calculated. Specifically, the main control device 28, based on the contrast data (contrast curve) of each evaluation point corresponding region DB _n corresponding to the optimal dose amount P _optn , for example, from the peak center of the contrast curve, H pattern, V pattern For each of these, the best focus position is obtained for each evaluation point corresponding region DB _n . Next, main controller 28 calculates, for each evaluation point corresponding area DB _n , the average value of the best focus positions obtained for each of the H pattern and V pattern as the best focus position at each evaluation point. Further, main controller 28 calculates the average value (or weighted average value) of the best focus positions at the evaluation points corresponding to evaluation point corresponding areas DB _{1 to} DB ₅ as the best focus position Z _best of projection optical system PL. .

The main controller 28 calculates the shape of the dynamic image plane based on the best focus position at each evaluation point. Further, the main controller 28 evaluates the evaluation points corresponding to the evaluation point corresponding regions DB _{1 to} DB ₅ based on the difference in the best focus position obtained for each of the H pattern and the V pattern for each evaluation point corresponding region DB _n. Astigmatism at may be calculated.

  In manufacturing the device, the main controller 28 performs the same step-and-scan exposure as described above, and transfers the pattern formed on the reticle R onto the wafer W. At this time, the main control device 28 corrects the optical characteristics of the projection optical system PL obtained as described above via an imaging characteristic correction controller (not shown). Adjust). Further, the main control device 28 effectively suppresses the occurrence of color unevenness due to defocusing by performing focus control of the wafer W with reference to the best focus position using the focus sensor AFS during exposure. . This makes it possible to transfer a fine pattern onto the wafer with high accuracy. The main controller 28 may calibrate the focus sensor with the best focus position as a reference prior to exposure.

As described above, according to the optical characteristic measuring method according to the present embodiment, the average value (? En k contrast value in the shot area S _k of a plurality (26) of each common conditions (focus position, the _{dose) ij} / 26) = aveE _{i, j} is used to obtain the optical characteristics of the projection optical system PL, so that the random error component included in the detection result of the measurement pattern image is reduced by the averaging effect, and the projection optical system It is possible to measure optical characteristics (for example, best focus position, dynamic image plane, etc.) of PL with high measurement stability.

Further, according to the optical characteristic measuring method according to the present embodiment, the pattern MP n the _(n = 1 to 5) upon exposure for transferring onto the wafer W _T, as an example, a pulse energy of illumination light IL normal The exposure amount (dose amount) can be accurately controlled by setting the amount smaller than the pulse energy amount set at the time of device manufacture and changing the number of pulses with respect to the pulse energy amount. Therefore, it is possible to reduce the influence of the control error of the exposure amount (dose amount) on the measurement result of the contrast / focus method.

Further, according to the optical characteristic measuring method according to the present embodiment, as in normal device fabrication, i.e., the exposure of the step-and-scan along a path BE (see FIG. 5), on the wafer W _T The measurement pattern MP _n is transferred, and the optical characteristics of the projection optical system PL are evaluated using the measurement pattern MP _n . Therefore, accurate measurement corresponding to actual exposure is possible. Here, it is also possible to evaluate the optical characteristics of the projection optical system PL for each scanning direction (± Y direction) of exposure.

  Further, according to the exposure apparatus 100 of the present embodiment, the main controller 28 accurately measures the optical characteristics of the projection optical system PL by the above-described optical characteristic measurement method, and takes into account the measurement result of the optical characteristics to perform projection. By adjusting at least one of the optical characteristics of the optical system PL and the position of the wafer W with respect to the direction of the optical axis AXp, the pattern image formed on the reticle R is projected onto the wafer W via the projection optical system PL, and the wafer W is exposed. This makes it possible to transfer a fine pattern onto the wafer with high accuracy.

In the above embodiment, a common condition (the focus position, the dose) Mean value of the contrast values in the 26 shot areas S _k for each _{(ΣE k, ij / 26)} = aveE i, a _j, evaluation points corresponding The optical characteristics of the projection optical system PL are obtained using the average value aveE _{i, j} obtained for each region DB _n . However, not limited thereto, it is also possible to determine the optical characteristics of the projection optical system PL by using the average value of the contrast values in some of the plurality of shot areas of the 26 pieces of shot areas S _k.

Alternatively, instead of _obtaining such an average value, the above-described jump data is replaced with the target dose in the same manner as the case where the contrast value E _{kn, ij} corresponding to the dose amount Q _kij closest to the target dose amount P _j is replaced. The contrast value E _{kn, ij} corresponding to the dose amount Q _kij closest to the amount P _j is extracted, and using this contrast value, the dose amount is determined and the best focus position of the projection optical system is determined in the same procedure as described above. Calculation may be performed. As will be described later, it is also possible to extract the contrast value E _{kn, ij} corresponding to the dose amount Q _kij closest to the target dose amount P _j from the shape (profile) of the contrast curve.

Alternatively, the obtained raw contrast value is corrected to the contrast value E _{i, j} corresponding to the target dose amount P _j in the same manner as in the case of correcting the jump data described above, and the corrected contrast value is obtained. By using the same procedure as described above, the dose amount may be determined and the best focus position of the projection optical system may be calculated. Even in this case, the influence of the dose control error can be reduced, so that the optical characteristics of the projection optical system PL can be accurately measured.

Further, in the above embodiment _, the extraction, correction, and the like of the contrast value E _{kn, ij} corresponding to the dose amount Q _kij closest to the target dose amount P _j described above may be applied to the contrast values other than the jump data. good. Also, if the distribution of the light amount of the illumination light IL irradiated on the exposure region on the wafer W _T is not constant, in advance by using the uneven illuminance sensor or the like to measure the illuminance unevenness in the exposure area, using the result of the contrast The value E _{kn, ij} may be corrected.

In the above embodiment, the main controller 28 determines the amount of illumination light IL emitted from the illumination system IOP and the dose amount Q (energy amount per pulse of the illumination light IL and the number of pulses) during exposure. Is being monitored. However, since the illumination light IL may be absorbed or scattered by the lens elements constituting the projection optical system PL, these amounts do not necessarily reflect the dose of the illumination light IL applied to the wafer. Therefore, it is also possible to measure environmental quantities such as temperature and pressure in the projection optical system PL, and evaluate the loss of the illumination light IL in the projection optical system PL based on the results. During exposure, the amount of illumination light IL emitted from the illumination system IOP and the dose amount Q at the time of exposure are stable, and in addition, by confirming that the environmental amount is stable, it is applied to at least the wafer. It can be determined that the dose of the illumination light IL is stable. Therefore, main controller 28 monitors the environmental quantity in projection optical system PL together with the intensity of illumination light IL in step 510, and after confirming that both of them are sufficiently stable, it starts exposure. It's also good. The main controller 28 records the environmental quantity in the projection optical system PL together with the dose Q at the time of exposure in the exposure history, and uses these records to evaluate appropriate contrast data E _knij when evaluating the optical characteristics. It is good also as sorting.

In the above embodiment, the best focus position, field curvature, or astigmatism is obtained as the optical characteristics of the projection optical system. However, the optical characteristics are not limited to these, and other aberrations may be used. In the above embodiment, the surface of the wafer W _T by a positive resist was assumed that sensitive layer is formed, this is not limited, it may be formed sensitive layer by a negative resist.

In the above-described embodiment, the entire evaluation point corresponding area is imaged simultaneously. However, for example, one evaluation point corresponding area may be divided into a plurality of areas and imaged. At this time, for example, the entire evaluation point corresponding region may be set in the detection region of the alignment system AS, and a plurality of portions of the evaluation point corresponding region may be imaged at different timings, or a plurality of portions of the evaluation point corresponding region May be sequentially set in the detection region of the alignment system AS and imaged. Furthermore, although the plurality of partition regions constituting one evaluation point corresponding region DB _n are formed adjacent to each other, for example, a part (at least one partition region) is formed as a detection region of the alignment system AS described above. You may form apart more than the distance corresponding to the magnitude | size. That is, the arrangement (layout) of a plurality of partition regions may be determined according to the size of the detection region of the alignment system AS so that the entire evaluation point corresponding region can be imaged simultaneously.

  In each of the above embodiments, the measurement pattern is transferred onto the wafer by scanning exposure, but still exposure may be used instead of scanning exposure. In this case, it is necessary to use a measurement reticle in which a measurement pattern is arranged in an area within a pattern area corresponding to the slit-shaped illumination area described above. In this case, it is possible to measure the static optical characteristics of the projection optical system by the same procedure as in the above embodiment.

  In addition, the exposure apparatus of the above embodiment may be an immersion type disclosed in, for example, International Publication No. 99/49504, US Patent Application Publication No. 2005/0259234, and the like, via a projection optical system and a liquid. By transferring the measurement pattern image onto the wafer, the optical characteristics of the projection optical system including the liquid can be measured.

  In the above embodiment, for example, the object to be imaged may be a latent image formed on a resist at the time of exposure. The wafer on which the image is formed is developed, and the wafer is etched. An obtained image (etched image) or the like may be used. In addition, the photosensitive layer on which an image on an object such as a wafer is formed is not limited to a photoresist, and may be any layer that can form an image (a latent image and a visible image) by irradiation with light (energy). It may be an optical recording layer, a magneto-optical recording layer, or the like.

  Further, in the above-described embodiment, the case where the resist image is picked up by the alignment type FIA sensor provided in the exposure apparatus is exemplified, but the present invention is not limited to this, and a dedicated image pickup apparatus (for example, an optical microscope) provided outside the exposure apparatus. Etc.), a resist image may be taken. In the above-described embodiment, the pattern image on the wafer is detected using the imaging type FIA system. However, in this measurement apparatus, the light receiving element (sensor) is not limited to the imaging element such as a CCD. Therefore, the data (pattern image measurement result by the measurement device) used in the above-described contrast information calculation is not limited to the imaging data.

When the L / S pattern is used as the measurement pattern, the duty ratio and the period direction may be arbitrary. When a periodic pattern is used as the measurement pattern MP _n , the periodic pattern is not limited to the L / S pattern, but may be a pattern in which dot marks are periodically arranged, for example.

  In the above embodiment, the position information of wafer stage WST is measured using an interferometer system. However, the present invention is not limited to this. For example, an encoder system that detects a scale (diffraction grating) provided on the upper surface of wafer stage WST. May be used. In this case, it is preferable that a hybrid system including both the interferometer system and the encoder system is used, and the measurement result of the encoder system is calibrated using the measurement result of the interferometer system. Further, the position of the wafer stage may be controlled by switching between the interferometer system and the encoder system or using both.

  Further, in the above-described embodiment, the case where the present invention is applied to the scanner has been described. However, not only a static exposure type projection exposure apparatus such as a stepper but also a step-and-stitch type exposure apparatus, a photo repeater, and the like. It can be suitably applied.

Furthermore, the light source of the exposure apparatus to which the present invention is applied is not limited to a KrF excimer laser or an ArF excimer laser, but may be an F ₂ laser (wavelength 157 nm) or another pulsed laser light source in the vacuum ultraviolet region. In addition, as the illumination light for exposure, for example, a fiber doped with erbium (or both erbium and ytterbium), for example, an infrared or visible single wavelength laser beam oscillated from a DFB semiconductor laser or fiber laser. Harmonics that are amplified by an amplifier and wavelength-converted to ultraviolet light using a nonlinear optical crystal may be used. Further, an ultra-high pressure mercury lamp that outputs a bright line (g-line, i-line, etc.) in the ultraviolet region may be used.

  Further, the projection optical system PL may be any of a refraction system, a catadioptric system, and a reflection system, and may be any of a reduction system, a unit magnification system, and an enlargement system.

  Furthermore, the present invention relates to an exposure apparatus for transferring a device pattern onto a glass plate, a thin film magnetic head, which is used for manufacturing not only an exposure apparatus used for manufacturing a semiconductor element but also a display including a liquid crystal display element and a plasma display. Also used in the manufacture of exposure equipment used to manufacture device patterns, exposure devices used to transfer device patterns onto ceramic wafers, imaging devices (CCDs, etc.), micromachines, DNA chips, etc., and masks or reticles can do.

  A semiconductor device includes a step of functional / performance design of a device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and an image of a reticle pattern by the exposure apparatus of the above-described embodiment. The wafer is manufactured through a step of generating the wafer, a step of developing the wafer, a step of etching the developed wafer, a device assembly step (including a dicing process, a bonding process, and a package process), an inspection step, and the like. In this case, in the lithography step, the exposure method described above is executed using the exposure apparatus of the above embodiment, and a device pattern is formed on the wafer. Therefore, a highly integrated device can be manufactured with high productivity.

  The optical property measurement method of the present invention is suitable for measuring the optical property of a projection optical system. The exposure method of the present invention is suitable for transferring a pattern onto an object via a projection optical system. The device manufacturing method of the present invention is suitable for manufacturing an electronic device.

28 ... main control unit, 100 ... exposure apparatus, AS ... alignment system, MP _n ... measurement patterns, DB _n ... evaluation point corresponding area, DA _{i, j} ... divided region, PL ... projection optical system, S k _... shot area , W _T ... wafer.

Claims (16)

An optical characteristic measurement method for measuring an optical characteristic of a projection optical system that projects an image of a pattern arranged on a first surface onto an object arranged on a second surface side,
The amount of energy beam irradiated onto the object disposed on the second surface side via the measurement pattern disposed on the first surface and the projection optical system is changed stepwise, and each energy is changed. Regarding the amount of beam, the position of the object in the optical axis direction of the projection optical system and the position of the object in the optical axis direction of the projection optical system are common while changing the position of the object in stages. Repetitively transferring the image of the measurement pattern to different partial areas inside each of the plurality of divided areas on the object with respect to a condition;
As a result of the repetition, an image of the measurement pattern formed in a plurality of partial regions inside each of a plurality of partition regions on the object is detected, and the detection result of the plurality of partition regions for each common condition is detected. Obtaining an optical characteristic of the projection optical system based on an average value;
An optical characteristic measuring method including:   The optical characteristic measurement method according to claim 1, wherein when the amount of the energy beam is changed step by step, the control accuracy of the amount of the energy beam is set with higher accuracy than when the device pattern image is projected.   When transferring the image of the measurement pattern, the energy beam is irradiated onto the object after confirming that the irradiation state of the energy beam including the environmental state in the projection optical system is sufficiently stable. The optical property measuring method according to claim 1 or 2. Each time an image of the measurement pattern is transferred onto the object, an irradiation condition including at least one of the intensity of the energy beam and an irradiation time is recorded,
The optical characteristic measurement method according to claim 1, wherein in the measurement of the optical characteristic, a detection result of the image of the measurement pattern is corrected based on the recorded irradiation condition.   The optical characteristic measurement method according to claim 4, wherein a detection result of the measurement pattern image is corrected using a relationship between the detection result obtained in advance and the irradiation condition. The relationship is determined with respect to the position of the object in the optical axis direction,
The optical characteristic measurement method according to claim 5, wherein when the optical characteristic of the projection optical system is obtained, the detection result of the image of the measurement pattern is corrected based on the position of the object in the optical axis direction.   When determining the optical characteristics of the projection optical system, the detection result of the position of the object and the measurement pattern image with respect to the optical axis direction of the projection optical system with respect to the amount of the energy beam irradiated on the object; The optical property measurement method according to claim 1, wherein the optical property is obtained based on the relationship.   The optical characteristic measurement method according to claim 7, wherein when the optical characteristic of the projection optical system is obtained, the relation is verified, and when the relation is ideal, the optical characteristic is obtained based on the relation.   9. When obtaining the optical characteristics of the projection optical system, the relationship is approximated by a curve, and the relationship is verified based on at least one of a shape of the curve and a deviation of the relationship from the curve. Optical property measurement method.   When determining the optical characteristics of the projection optical system, an optimal amount of the energy beam for measuring the optical characteristics of the projection optical system is determined based on the detection result of the image of the measurement pattern, and the optimal amount The optical characteristic measuring method according to claim 1, wherein the optical characteristic is obtained based on the detection result corresponding to the above. The measurement pattern includes first and second patterns in which the first and second axes orthogonal to each other in the first surface are arranged directions, respectively.
When determining the optical characteristics of the projection optical system, first and second relationships between the position of the object in the optical axis direction of the projection optical system and the detection results of the images of the first and second patterns, respectively. The optical property measurement method according to claim 1, wherein the optical property is obtained based on the first and second relationships. Detecting the image of the measurement pattern includes capturing the image;
The optical characteristic measurement method according to claim 1, wherein the detection result is a calculation result of light / dark information in each of the plurality of partitioned regions obtained by imaging.   13. When the image of the measurement pattern is transferred onto the object, the measurement pattern and the object are synchronously driven in a direction orthogonal to the optical axis of the projection optical system. The optical property measuring method described in 1. A projection optical system for projecting an image of a pattern arranged on the first surface onto an object arranged on the second surface side using the optical characteristic measurement method according to any one of claims 1 to 13. Measuring the optical properties of;
In consideration of the measurement result of the optical characteristic, at least one of the optical characteristic of the projection optical system and the position of the object with respect to the optical axis direction of the projection optical system is adjusted, and the image of the pattern is converted into the projection optical system. And exposing the object by projecting onto the object disposed on the second surface side through the exposure method. The object has a sensitive layer;
The exposure method according to claim 14, wherein the object is exposed by irradiating the sensitive layer with an energy beam. Forming a pattern on an object using the exposure method according to claim 14 or 15;
Processing the object on which the pattern has been formed.

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