JPH09330862A - Method for adjusting aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of the accuracy management of an aligner by eliminating offsets caused by the errors of an alignment sensor and reference plate themselves. SOLUTION: A parameter value for adjusting an aligner is statistically found from the superposition error between a first-layer pattern formed by applying a resist to a reference plate carrying a reference mark pattern and printing a checking pattern to the resist in a state where the accuracy of an aligner meets a specification and a second-layer pattern measured with an alignment sensor and the parameter value is used as a base value. When the adjustment of the aligner becomes necessary due to a secular change, etc., the checking pattern used at the time of finding the base value is printed to the same reference plate as that used at the time of finding the base value and the superposition is measured with the alignment sensor and the parameter value for adjusting the aligner is calculated from the superposition error between the first- and second-layer patterns. Then a variation correcting parameter is obtained by subtracting the base value form the parameter value for adjusting the aligner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of adjusting an exposure apparatus used for manufacturing semiconductor elements, liquid crystal display elements and the like.

[0002]

2. Description of the Related Art In a lithography process for manufacturing a semiconductor device or a liquid crystal display device, a semiconductor wafer or a glass plate on which a device pattern formed on a reticle or a photomask (hereinafter referred to as a mask) is coated with a photosensitizer such as photoresist. An exposure device is used as a device for transferring with high resolution onto a photosensitive substrate such as.

In the exposure apparatus, it is necessary to align the mask and the photosensitive substrate with high accuracy in order to superimpose and expose the pattern of the next layer on the pattern already formed on the photosensitive substrate. . As an alignment sensor for that purpose, an LS that irradiates a laser beam onto a dot-column-shaped alignment mark on a photosensitive substrate and detects the mark position using the light diffracted or scattered by the mark.
A (Laser Step Alignment) method, FI that measures the image data of the alignment mark imaged by illuminating it with light with a wide wavelength band using a halogen lamp as a light source
A (Field Image Alignment) method or a diffraction grating-like alignment mark on the photosensitive substrate is irradiated with laser light with slightly different frequencies from two directions, and the two generated diffracted lights are caused to interfere with each other, and the alignment mark is obtained from the phase. LIA (Laser Interferometric Alignm)
ent) type alignment sensor. The alignment method is a TTL (through-the-lens) method that measures the position of the photosensitive substrate via the projection optical system, and a TTM (through method) that measures the positional relationship between the mask and the photosensitive substrate via the projection optical system and the mask. -The mask) method and the off-axis method that directly measures the position of the photosensitive substrate without using the projection optical system.

By detecting the positions of at least two points of the photosensitive substrate placed on the substrate stage by these alignment sensors, the position (rotation angle) in the translational direction and the rotational direction of the photosensitive substrate can be detected. . As a sensor used for measuring the rotation angle of the photosensitive substrate, TT
There are LIA type LIA type, TTL type LSA type, and off-axis type FIA type alignment sensors.

In addition to the alignment of the mask and the photosensitive substrate by these alignment sensors, the accuracy of the exposure apparatus itself,
For example, strict accuracy control is required for scaling of the stage drive system in the X and Y directions, orthogonality of the stage drive system, shift of the origin of the substrate stage in the X and Y directions, and lens magnification. Since the accuracy of these devices changes with time, conventionally, it is possible to periodically measure the device accuracy using a reference plate on which a reference pattern is formed by chrome etching and correct the device parameters to obtain the desired accuracy. It was done.

That is, a resist-coated reference plate is aligned by an exposure device to expose a pattern for checking overlay accuracy. After observing the reference plate where the check pattern was exposed, measure the reference mark of the chromium layer corresponding to the main scale and the mark position of the check pattern of the resist layer corresponding to the vernier scale with the alignment sensor of the device, The overlay error is calculated from the relative distance between the main scale and the vernier scale and its design value. By statistically processing the overlay error data obtained at a plurality of measurement points on the reference plate, scaling of the stage drive system in the X and Y directions, substrate stage rotation, orthogonality of the substrate stage drive system, X direction, and The device correction parameters such as the origin shift in the Y direction, the lens magnification error, and the mask stage rotation are calculated, stored in the device adjustment parameter file, and used for the correction.

[0007]

The value measured by the alignment sensor provided in the exposure apparatus includes an offset peculiar to the sensor. Further, the reference plate also includes an offset based on a mark forming error when the reference plate is manufactured. In the above-mentioned accuracy control of the conventional exposure apparatus, there is a problem that an accurate apparatus correction value cannot be obtained because the measurement value includes an offset due to the error of the alignment sensor or the reference plate itself. there were. The present invention has been made in view of the above problems of the conventional art, and an object thereof is to improve the accuracy of accuracy control of an exposure apparatus using a reference plate.

[0008]

According to the present invention, a check is performed by applying a resist to a reference plate on which a reference mark pattern (first layer pattern) is formed by chrome etching while the device accuracy is within the standard. The pattern (second layer pattern) is printed, the device adjustment parameters are obtained by statistical processing from the overlay error of the first layer pattern and the second layer pattern measured by the alignment sensor, and these are stored in the base data file as base values. .
This base value represents an offset peculiar to the alignment sensor of the exposure apparatus and a manufacturing error of the reference plate itself.

Next, when it becomes necessary to adjust the device due to a change with time or the like, the same check pattern (second layer pattern) as that at the time of deriving the base value is set on the same reference plate as that used for calculating the base value. Is printed, and overlay measurement is performed using an alignment sensor, and a device adjustment parameter is calculated from the overlay error between the first layer pattern and the second layer pattern. Then, a value obtained by subtracting the base value from the calculated device adjustment parameter is stored as a device variation correction parameter in the variation correction parameter file, and this variation correction parameter is used for the device adjustment.

During the second and subsequent device adjustments, the variation correction parameter stored at that time is added to the difference between the device adjustment parameter and the base value obtained by a similar procedure, and the result is renewed. It was stored in a fluctuation correction parameter file as a fluctuation correction parameter and used for adjusting the apparatus.

That is, according to the present invention, in an exposure apparatus adjusting method for transferring a mask pattern onto a photosensitive substrate, a plurality of reference marks are formed on a reference plate on which a plurality of reference marks are formed. The first step of exposing the check pattern and the overlay of the reference mark on the reference plate and the check pattern exposed in the first step are measured, and the device adjustment parameters are obtained from the measurement results and used as the base value. The second step of remembering,
The third step of exposing the check pattern on the reference plate after the second step, and the overlay of the reference mark on the reference plate and the check pattern exposed in the third step are measured, and the measurement result is used to determine the apparatus. A fourth step of obtaining an adjustment parameter, a difference between the apparatus adjustment parameter obtained in the fourth step and the base value is stored as a variation correction parameter, and the exposure apparatus is adjusted based on the variation correction parameter. And a step.

During the second and subsequent device adjustments in which the fluctuation correction parameters are already stored, in the fifth step, the difference between the device adjustment parameter obtained in the fourth step and the base value is stored at that time. The value obtained by adding the existing fluctuation correction parameter is stored as a new fluctuation correction parameter, and the exposure apparatus is adjusted based on this new fluctuation correction parameter.

The device adjustment parameters include scaling of the substrate stage drive system that moves the photosensitive substrate two-dimensionally, rotation error of the substrate stage, orthogonality error of the substrate stage drive system, origin shift of the substrate stage, and projection optics. It can be at least one of a system magnification error and a mask stage rotation error.

An offset unique to the sensor and an error component of the reference plate itself are commonly included in the device adjustment parameters obtained by the base value and the measurement during the subsequent adjustment. Therefore, when the base value is subtracted from the device adjustment parameter obtained by the measurement at the time of device adjustment, those offsets and errors are canceled and a parameter that purely reflects only the accuracy variation of the exposure apparatus is obtained. Therefore, if this is used as a variation correction parameter and the apparatus is adjusted using this variation correction parameter, the exposure apparatus can be returned to the original standard state.

During the second and subsequent device adjustments, in the fifth step, the variation correction parameter stored at that time is added to the difference between the device adjustment parameter obtained in the fourth step and the base value, and the actual value is added. The reason why the fluctuation correction parameter used for the apparatus adjustment is obtained is that the exposure apparatus has already been adjusted with the fluctuation correction parameter at that time. In other words, since the adjustment parameter is obtained by the exposure apparatus that is adjusted (biased) with the variation correction parameter at that time, the obtained variation correction parameter is set in the apparatus at that time. This is the change amount with respect to the fluctuation correction parameter that is present. Therefore,
In order to obtain the correction parameter necessary for the apparatus adjustment, in other words, the fluctuation correction parameter for returning to the exposure apparatus in the standard state, it is necessary to add the fluctuation correction parameter currently set in the apparatus.

The exposure apparatus according to the present invention comprises storage means,
The storage means stores a base data file in which a base value is described and a variation correction parameter file in which variation correction parameters are described. The control system of the exposure system
By referring to the contents of the variation correction parameter file stored in the storage unit, the substrate stage driving unit, the mask stage driving unit, the lens controller for adjusting the projection magnification of the projection optical system, and the like are controlled to set the exposure apparatus within the standard. Adjust to the state.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an example of an exposure apparatus according to the present invention. The exposure light IL emitted from the illumination optical system 1 illuminates the mask 2 on which a pattern to be exposed is formed with a substantially uniform illuminance. The mask 2 is held on a mask stage 3, and the mask stage 3 is supported so that it can be moved and finely rotated in a two-dimensional plane on a base 4. A main control system 6 that controls the operation of the entire apparatus controls the operation of the mask stage 3 via a mask stage driving device 5 on the base 4. Mask alignment system 25
Detects the alignment mark formed on the mask 2 and aligns the mask 2. The mask alignment system 25 includes the reference member 2 provided on the substrate stage 10.
Calibrated by 4.

Under the exposure light IL, the pattern image of the mask 2 is projected onto each shot area on the photosensitive substrate 8 via the projection optical system 7. The photosensitive substrate 8 is mounted on the substrate stage 10 via the substrate holder 9. Substrate stage 1
Reference numeral 0 denotes an XY stage for two-dimensionally positioning the photosensitive substrate 8 in a plane perpendicular to the optical axis 7a of the projection optical system 7, and the photosensitive substrate 8 in the direction (Z direction) parallel to the optical axis 7a of the projection optical system 7. And a θ stage for rotating the photosensitive substrate 8 minutely. A reference member 24 having a reference mark is provided on the substrate stage 10 at the same height as the surface of the photosensitive substrate 8.

A movable mirror 11 that moves together with the stage 10 is fixed on the upper surface of the substrate stage 10, and the movable mirror 1
A laser interferometer 12 is arranged so as to face 1. Although shown in a simplified manner in FIG. 1, the projection optical system 7
The movable mirror 11 is composed of a plane mirror having a reflection surface perpendicular to the X axis and a plane mirror having a reflection surface perpendicular to the Y axis. There is. Further, the laser interferometer 12 includes two laser interferometers for X-axis that irradiate the moving mirror 11 with a laser beam along the X-axis and a Y-axis for irradiating the moving mirror 11 with a laser beam along the Y-axis. X laser interferometer
The X coordinate and the Y coordinate of the substrate stage 10 are measured by one laser interferometer for the axis and one laser interferometer for the Y axis. The coordinate system (X, Y) composed of the X coordinate and the Y coordinate measured in this way is hereinafter referred to as a stage coordinate system.

The rotation angle of the substrate stage 10 is measured by the difference between the measured values of the two laser interferometers for the X axis. Information on the X coordinate, the Y coordinate, and the rotation angle measured by the laser interferometer 12 is supplied to the coordinate measuring circuit 12a and the main control system 6, and the main control system 6 monitors the supplied coordinates and drives the substrate stage drive device. The positioning operation of the substrate stage 10 is controlled via 13. Although not shown in FIG. 1, the mask side is also provided with the same interferometer system as the photosensitive substrate side.

An imaging characteristic control device 14 is mounted on the projection optical system 7. The image formation characteristic control device 14 adjusts, for example, an interval between predetermined lens groups in the lens groups forming the projection optical system 7 or a gas pressure in the lens chamber between the predetermined lens groups. The projection magnification and distortion of the projection optical system 7 are adjusted.

The main control system 6 has a storage unit, and while referring to the device parameters stored in the storage unit, the mask stage drive unit 5, the substrate stage drive unit 13, and the mask stage drive unit 13, so that a predetermined device precision is realized. Also, the imaging characteristic control device 14 is controlled. The storage unit of the main control system 6 stores a base data file that describes base values of device adjustment parameters, which will be described later, and a fluctuation correction parameter file that stores device parameters for correcting device fluctuations over time. .

An off-axis type LSA (Laser Step Alignment) type substrate alignment system 15 is arranged on the side surface of the projection optical system 7. In this substrate alignment system 15, alignment light emitted from a laser light source 16 such as a He-Ne laser or a semiconductor laser is made into a linear beam by a cylindrical lens 17, and a beam splitter 18, an objective lens 19 and an epi-illumination mirror 20 are provided. An image is formed as a linear beam in the vicinity of the alignment mark 29 on the photosensitive substrate 8 via the light.

FIG. 2 is a schematic view showing the relationship between the alignment laser beam 23 and the alignment mark 29X for positioning in the X direction provided on the photosensitive substrate 8. The linear laser beam 23 irradiates an alignment mark (diffraction grating mark) 29X formed on the photosensitive substrate 8, and when the both are relatively scanned, diffracted light or scattered light is generated from the alignment mark 29X.

The diffracted light or scattered light from the alignment mark 29X enters the detector 22 via the mirror 20, the objective lens 19, the beam splitter 18, and the relay lens 21 of the substrate alignment system 15. Detector 22
The detection signal from is supplied to the coordinate position measuring circuit 12a. In the figure, only the alignment mark 29X for position detection in the X direction in which the dot rows are arranged in the Y direction is shown, and LSA is also X.
Only those for directional position detection are shown. In practice, the alignment mark 29 is also provided with an alignment mark for position detection in the Y direction in which dot rows are arranged in the X direction.
A is also provided for position detection in the Y direction.

From the output of the detector 22 and the measurement result of the laser interferometer 12 at that time, the coordinate position measuring circuit 12a
The stage coordinate system (X,
Y) The coordinates on the screen are obtained, and the measured coordinate values are used for the main control system 6
To supply. The substrate alignment system 15 used in the present invention is not limited to the LSA type, and other types may be adopted.

FIG. 3 is a schematic view of a test mask for exposing the check pattern on the reference plate. This test mask 40 has marks 41-at the four corners.
N (N = 1, 2, 3, 4) is provided. Each mark 41-N is a mark 41 for position measurement in the X direction.
-NX (N = 1, 2, 3, 4) and Y-direction position measuring mark 41-NY (N = 1, 2, 3, 4). The position measuring mark 41-NX in the X direction is a diffraction grating mark in which dot rows are arranged in the Y direction as schematically shown in FIG.
The Y-direction position measurement mark 41-NY is a diffraction grating mark in which dot rows are arranged in the X-direction.

FIG. 4 is an explanatory view of the reference plate. The reference plate 43 is formed by using, for example, a reference exposure device, and
It is produced by forming a pattern similar to the pattern of the test mask 40 shown in FIG. First, a chrome plate having a chrome layer deposited on the surface is coated with a photoresist, which is placed on a substrate stage of a reference exposure apparatus, and a pattern of a test mask is exposed by a step-and-repeat method. The exposed chrome plate is developed and then etched to leave a chrome layer only in the mark areas. Thus, a plurality of shot areas 27 are formed along the orthogonal coordinate system (α, β) on the plate.
-N (n = 1, 2, ..., 9) are arranged in a matrix form, and the reference plate 43 in which the pattern of the test mask 40 shown in FIG. 3 is formed in each shot area 27-n is obtained.

Each shot area 27 of the reference plate 43-
A reference position is defined for each n. For example, when the reference position is the center point 28-n of each shot area 27-n, the designed coordinate values of this reference point 28-n in the coordinate system (α, β) on the reference plate 43 are (C
_Xn , C _Yn ). Further, in this example, four marks 29-n, 30- are provided in each shot area 27-n.
n, 31-n, and 32-n are provided together. The coordinate system (x, y) on the shot area is set in each shot area 27-n in parallel with the coordinate system (α, β) on the reference plate of FIG. 4A, as shown in FIG. 4B. Then, the marks 29-n, 30-n, 31 in the coordinate system (x, y) are
Design coordinates of −n and 32-n are (S _1Xn , S
_1Yn ), ( _S2Xn , _S2Yn ), ( _S3Xn , _S3Yn ) and ( _S4Xn , _S4Yn ). It should be noted that the reference plate used in the present invention does not need to be formed by strictly controlling each mark position as long as the same reference plate is used at the time of acquiring the base data and at the time of acquiring the device adjustment parameter thereafter.

Next, a method for adjusting the exposure apparatus shown in FIG. 1 using the reference plate 43 shown in FIG. 4 and the test mask 40 shown in FIG. 3 will be described. First, the acquisition of the base data regarding the device adjustment parameters of the exposure apparatus will be described. The acquisition of the base data is performed in a state where the apparatus accuracy of the exposure apparatus shown in FIG. 1 is within the standard. The test mask 40 is aligned by the mask alignment system 25 and held on the mask stage 3. The reference plate 43 coated with photoresist is placed on the substrate stage 10 of the exposure apparatus, and the reference plate 43 is aligned using the substrate alignment system 15. Thereafter, while the substrate stage driving device 13 is stepping the substrate stage 10, each shot area 2 of the reference plate 43 is
The pattern of the test mask 40 is exposed by superimposing it on 7-n. After the exposure of all the shot areas 27-1 to 27-9 is completed, the reference plate 43 is unloaded from the substrate stage 10 and development is performed.

After the development, the reference plate 43 having the mark formed by the resist on the surface is placed on the substrate stage 10 of the exposure apparatus again, and the substrate alignment system 15 forms a test pattern (chrome mark) on the reference plate 43. The positional deviation at each point is measured from the relative distance to the overlay pattern (resist mark). After that, the apparatus adjustment parameter of the exposure apparatus is obtained and stored as a base value in the base file. The device adjustment parameter can be obtained by, for example, the same statistical calculation as EGA (Enhanced Global Alignment) described in JP-A-61-44429.

The method of obtaining the device adjustment parameters will be described below. Here, as device adjustment parameters for the substrate stage system, scaling Rx in the X direction of the stage drive system, scaling Ry in the Y direction of the stage drive system, rotation error Θ of the stage with respect to the stage coordinate system (X, Y), stage Orthogonality error W in which the X-direction and Y-direction feeds are not exactly orthogonal, the X-direction shift O _X of the stage origin with respect to the stage coordinate system,
And a shift O _{Y in the} Y direction. A magnification error M of the projection optical system will be considered as a device adjustment parameter for the projection optical system. Further, a rotation error θ of the mask stage with respect to the stage coordinate system (X, Y) is considered as a device adjustment parameter for the mask stage system. When there is such an error, the design coordinate values (C _Xn , C _Yn ) of the reference points of the respective shot areas become the coordinates (C ′ _Xn , C ′ _Yn ) represented by the following equation [Equation 1]. Moving.

[0033]

[Equation 1]

Here, the orthogonality error W and the residual rotation error Θ
When the linear approximation is performed assuming that is a small amount, [Equation 1] is expressed as [Equation 2] below.

[0035]

[Equation 2]

Further, if there is a magnification error M of the projection optical system 7 and a rotation error θ of the mask stage 3, design coordinate values (S) on the coordinate system (x, y) of an arbitrary shot area 27-n will be described.
_{Mark 29-} located at _NXn , S _NYn ) (N = 1 to 4)
n, 30-n, 31-n and 32-n are formed at the coordinates (S ′ _NXn , S ′ _NYn ) represented by the following [ _Equation 3]. However, linear approximation was performed assuming that the orthogonality error w and the rotation error θ are minute amounts. In the expression of the coordinate values (S _NXn , S _NYn ), n represents the number of the shot area, and N represents the position within the shot.

[0037]

(Equation 3)

In FIG. 4B, the array coordinate value of the reference point 28-n of an arbitrary shot area 27-n on the stage coordinate system (X, Y) is (C _Xn , C _Yn ). Therefore, an arbitrary mark 29-n on that arbitrary shot area is
Design coordinate values (D _NXn , D _NYn ) on the stage coordinate system (X, Y) of up to 32-n are expressed as in the following [ _Equation 4]. However, as described above, the alignment marks 29-n to 32-n are distinguished by the value of N (1 to 4).

[0039]

(Equation 4)

When the test mask 40 is exposed by the exposure apparatus of FIG. 1, the marks 29-n, 30-n, 31-n, 3 are formed.
If the coordinates of the position where 2-n should actually be on the stage coordinate system (X, Y) are (F _NXn , F _NYn ) (N = 1 to 4), this coordinate value (F _NXn , F _NYn ) is From [Equation 2] and [Equation 3], the following [Equation 5] is used.

[0041]

(Equation 5)

Here, the scaling Rx in the α direction and the scaling Ry in the β direction in [Equation 5] are expressed by the following [Equation 6] using new parameters Γx and Γy, respectively.

[0043]

## EQU00006 ## Rx = 1 + .GAMMA.x, Ry = 1 + .GAMMA.y

Two parameters Γ indicating these changes
When [Equation 5] is rewritten using x and Γy, [Equation 5] becomes approximately like [Equation 7] below.

[0045]

(Equation 7)

Eight device adjustment parameters Γx (= Rx-1) and Γy (=) included in the coordinate conversion formula of the above [Formula 7].
Ry-1), Θ, W , O X, O Y, M, θ can be determined for example by the least squares method. The numerical value of the apparatus adjustment parameter thus obtained is stored as a base value in the base file of the storage area in the main control system 6 of the exposure apparatus. As is clear from the above description, this base value is the value of the apparatus adjustment parameter when the exposure apparatus has the accuracy within the standard, and the alignment system 15, 25 provided in the exposure apparatus. And an offset peculiar to the reference plate and a mark forming error of the reference plate.

Next, with reference to the flow chart of FIG. 5, a method for newly measuring the apparatus adjustment parameter after obtaining the base data and adjusting the exposure apparatus based on the parameter will be described. The measurement of the device adjustment parameter is performed using the same reference plate 43 as that used when acquiring the base data. The test mask 40 shown in FIG. 3 is aligned and held by the mask alignment system 25 on the mask stage 3 of the exposure apparatus.

First, a resist is applied to the reference plate 43 (S11). Then, the reference plate 43 coated with the resist is placed on the substrate stage 10 of the exposure apparatus,
After aligning at a predetermined position using the substrate alignment system 15, the pattern of the test mask 40 is exposed on each shot area 27-n (n = 1 to 9) on the reference plate 43. When the exposure of one shot area is completed, the main control system 6 causes the substrate stage driving device 13 to step the substrate stage 10 in the X and Y directions by a predetermined distance, and moves the next shot area to the lower side of the projection optical system 7. Positioning and exposing are repeated. When the exposure of all shot areas is completed, the reference plate 43 is unloaded from the reference stage and developed (S12).

Next, the developed reference plate 43 is placed on the substrate stage 10 of the exposure apparatus again, and the substrate alignment system 15 is used to superimpose the reference pattern on the reference plate consisting of chrome marks and the resist mark. The relative distance of the alignment pattern is measured (S13). Using the positional deviation data obtained at each measurement point, the device adjustment parameter Γx (= Rx-
1), Γy (= Ry- 1), Θ, W, O X, O Y, M, θ
Is calculated (S14).

Now, each device adjustment parameter Γx, Γ
The base values of y, Θ, W, O _X , O _Y , M, and θ are β ₁ , respectively.
beta _2, ..., when the beta _8, vector beta for these base values and the component _{(β 1, β 2, ...} , β 8) consider. Also,
The device adjustment parameter Γx obtained in step 14,
The values of Γy, Θ, W, O _X , O _Y , M, and θ are α ₁ , α ₂ , and
, Α ₈ , consider a vector α _m (α _m1 , α _m2 , ..., α _m8 ) having these values as components. Step 15
Then, the variation correction parameters γ _m1 , γ _m2 , ..., γ _m8 are obtained by subtracting the base value of the parameter from the device adjustment parameter obtained in step 14 and written in the variation correction parameter file (S15). γ _m1 , γ _m2 ,…,
vector γ _m (γ _m1 to the gamma _m8 and components, γ _m2, ...,
Considering γ _m8 ), the calculation in step 15 can be expressed as the following [Equation 8]. The subscript _m attached to the vectors α _m and γ _m indicates that the device adjustment this time is the m-th device adjustment after the base data is acquired.

[0051]

Γ _m = α _m −β

If the apparatus adjustment this time is the first adjustment (m = 1) since the base data was acquired, the process proceeds from step 16 to step 18 to obtain the determined parameters γ ₁₁ , γ ₁₂ ,. , Γ ₁₈ are written in the fluctuation correction parameter file in the main control system 6. Continued Step 19
Then, the exposure apparatus is adjusted according to the contents of the variation correction parameter file. That is, in the subsequent pattern exposure, the drive control of the substrate stage drive unit 13 is adjusted with reference to the variation correction parameter file in which the values of the components of the parameters γ ₁₁ , γ ₁₂ , ..., γ ₁₈ are written. By this, the stepping scale, rotation of the substrate stage 10,
The orthogonality and the shift of the origin are adjusted, and the imaging characteristic control device 14
To adjust the magnification of the projection optical system 7 and adjust the drive control of the mask stage drive device 5 to adjust the rotation of the mask stage 3. By this device adjustment, the exposure device can perform the pattern exposure in a state within the same standard as when the base data was acquired.

If the adjustment of the exposure apparatus this time is the second or subsequent adjustment after the acquisition of the base data (m ≧ 2), the process proceeds from step 16 to step 17. In step 17,
As represented by the following [Equation 9], the value of the parameter γ _m-1 stored in the fluctuation correction parameter file at that time is added to the fluctuation correction parameter (α _m −β) obtained in step 15. Is added, and a new variation correction parameter γ _m
Is calculated.

[0054]

Γ _m = γ _m-1 + (α _m −β)

Next, in step 18, the obtained parameters γ _m1 , γ _m2 , ..., γ _m8 are written in the fluctuation correction parameter file in the main control system 6. In the following step 19, the exposure apparatus is adjusted according to the contents of the fluctuation correction parameter file. That is, at the time of subsequent pattern exposure, referring to the variation correction parameter file in which the values of the respective components of the parameters γ _m1 , γ _m2 , ..., γ _m8 are written,
The stepping scale, rotation, orthogonality, and shift of the origin of the substrate stage 10 are adjusted by adjusting the drive control of the substrate stage driving device 13, and the imaging characteristic control device 14 is controlled to adjust the magnification of the projection optical system 7. The mask stage 3 is adjusted by adjusting the drive control of the mask stage drive device 5.
Adjust the rotation of. By this device adjustment, the exposure device
The pattern exposure can be performed in the same standard as when the base data was acquired.

[0056]

According to the present invention, an accurate correction value for an exposure apparatus that does not include an offset due to an error in the alignment sensor or the reference plate itself can be obtained, so that the exposure apparatus can be adjusted with high accuracy and easily. You can

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an exposure apparatus according to the present invention.

FIG. 2 is a diagram illustrating a relationship between an alignment mark and a laser beam in an LSA type alignment system.

FIG. 3 is a schematic view of a test mask.

FIG. 4 is an explanatory view of a reference plate.

FIG. 5 is a flowchart illustrating a procedure of device adjustment.

[Explanation of symbols]

1 ... Illumination optical system, 2 ... Mask, 3 ... Mask stage, 4
... base, 5 ... mask stage drive device, 6 ... main control system, 7 ... projection optical system, 8 ... photosensitive substrate, 9 ... substrate holder, 10 ... substrate stage, 11 ... moving mirror, 12 ... laser interferometer, 12a ... Coordinate measuring circuit, 13 ... Substrate stage drive device, 14 ... Imaging characteristic control device, 15 ... Substrate alignment system, 16 ... Laser light source, 17 ... Cylindrical lens, 19 ... Objective lens, 22 ... Detector, 24 ... Reference member, 25 ... Mask alignment system, 29 ... Alignment mark, 40 ... Test mask, 43 ... Reference plate

Claims (3)

[Claims] 1. A method of adjusting an exposure apparatus for transferring a mask pattern onto a photosensitive substrate, wherein a plurality of check patterns corresponding to the plurality of reference marks are formed on a reference plate on which a plurality of reference marks are formed. The first step of exposing, the overlay of the reference mark on the reference plate and the check pattern exposed in the first step is measured, and an apparatus adjustment parameter is obtained from the measurement result and stored as a base value. A second step; a third step of exposing the check pattern on the reference plate after the second step; an overlay of the reference mark on the reference plate and the check pattern exposed in the third step Fourth, measuring the alignment and obtaining the device adjustment parameter from the measurement result
And a difference between the device adjustment parameter obtained in the fourth step and the base value is stored as a variation correction parameter,
And a fifth step of adjusting the exposure apparatus based on the variation correction parameter. 2. In the fifth step, a value obtained by adding a variation correction parameter stored at that time to a difference between the device adjustment parameter obtained in the fourth step and the base value is newly changed. The exposure apparatus adjusting method according to claim 1, wherein the exposure apparatus is stored as a parameter for adjustment, and the exposure apparatus is adjusted based on the new variation correction parameter. 3. The apparatus adjustment parameter includes scaling of a substrate stage drive system that two-dimensionally moves while placing the photosensitive substrate, rotation error of the substrate stage, orthogonality error of the substrate stage drive system, and the substrate. 2. The exposure apparatus adjusting method according to claim 1, wherein at least one of a stage origin shift, a projection optical system magnification error, and a mask stage rotation error.