JPH10335208A - Exposure method for aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control the focusing position of a projection lens which is optimum for forming a projection pattern image in the exposure method using an optical stepper in a lithography step for printing a circuit pattern, formed on a reticle to a resist on a wafer. SOLUTION: A focus-detecting rectangular pattern CPa, susceptible to optical proximity effect, is provided on a reticle having an element circuit pattern for a projection pattern image RPa to be formed on a wafer, depending on the change of the exposure conditions. At exposure, the projection pattern image RPa of the focus-detecting pattern CPa is read to obtain its lateral length LxRPa , from which the correction value ΔF for correcting the deviation from the focus position of the projection lens is calculated. Thus a circuit pattern is exposed, while always correcting for the focus deviation of the projection lens.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method of an exposure apparatus for projecting a mask pattern formed on a reticle onto a wafer through a projection optical system, and more particularly to a method for exposing a circuit pattern of a semiconductor wafer to a semiconductor wafer. The present invention relates to an exposure method of a step-and-repeat type reduction projection light exposure apparatus used in a lithography process for printing on an upper resist.

[0002]

2. Description of the Related Art As is well known, in a manufacturing process of a semiconductor integrated circuit device such as a VLSI, in particular, in a lithography process, a step-and-repeat reduction projection type light exposure apparatus (optical stepper) is mainly used. Have been.

The optical stepper sequentially reduces and projects a circuit pattern of a semiconductor integrated circuit element formed on a reticle onto a semiconductor wafer through a projection lens, thereby forming the circuit pattern on a resist on the wafer. The projection pattern image is transferred.

At this time, unless the focal position of the projection lens is accurately adjusted, the projected image of the circuit pattern formed on the reticle will not be accurately formed on the wafer, and the projected image will be out of focus on the wafer. Since a pattern image is formed, a problem of so-called poor resolution occurs.

As described above, unless the exposure conditions of the optical stepper, including the focal position of the projection lens, are properly set, it is impossible to obtain a semiconductor integrated circuit device satisfying the desired characteristics.

Therefore, in order to prevent such a problem,
Conventionally, the following method has been adopted. For example,
A plurality of rectangular patterns having different line widths including a pattern smaller than the minimum line width of the circuit pattern formed on the reticle are changed for each shot by changing exposure conditions (focal position and exposure amount of the projection lens). It is sequentially transferred onto a semiconductor wafer.

Next, the line width of the resist pattern formed on the wafer by performing the development processing is measured by, for example, an SEM length measurement method using a scanning electron microscope or a television camera (IT).
The measurement is performed using an image processing method according to V) or a method of irradiating the resist pattern with spot light and detecting the scattered light.

[0008] Then, the optimum conditions for forming the resist pattern are determined from the line width, and the exposure conditions of the optical stepper such as the focal position of the projection lens and the exposure amount are adjusted in accordance with the optimum conditions.

In this way, after the exposure conditions are reset, the lithography process is started, and the circuit patterns formed on the reticle for the semiconductor integrated circuit are sequentially transferred onto the semiconductor wafer. Thus, a circuit pattern can be formed under optimal exposure conditions.

However, in the above-mentioned method using a scanning electron microscope for measuring the line width of the resist pattern, there is a problem that the microscope itself is very expensive and the measurement requires time.

Further, in the method of measuring the line width using the ITV or the spot light, it is difficult to measure the line width when the line width is about sub-micron, and even if the measurement can be performed, the error is large. was there.

In recent years, in view of the above-mentioned problems, it is possible to calculate the optimum forming conditions with high accuracy and in a short time by preventing the measurement accuracy of the resist pattern from being lowered, thereby shortening the setup time of the stepper. Exposure methods have been proposed (see, for example, JP-A-1-187817).
No.).

FIG. 12 shows an example of a linear pattern used for calculating the optimum forming conditions disclosed by the above proposal. FIG. 2A shows a case where a linear pattern is used.
Length L _CP that combines two wedge-shaped patterns symmetrically
5 shows a substantially rhombic pattern CP having the following pattern.

FIG. 1B shows a change in the length L _RP of the projection pattern image (resist pattern) RP of the pattern CP due to a defocus of the projection lens.

FIG. 1C shows the relationship between the change in the length L _RP of the projection pattern image RP and the defocus amount. As described above, the length L _RP of the resist pattern RP formed on the semiconductor wafer by projecting the pattern CP changes in proportion to the defocus amount from the focus position of the projection lens. Therefore, for example, by measuring the length L _RP of the resist pattern RP with the alignment detector of the optical stepper, it is possible to detect the optimal focus position of the projection lens for forming the projection pattern image.

That is, in this method, as a result of the measurement by the alignment detector, the length L _{RP of the} resist pattern RP is obtained.
Is detected as the optimal focus position of the projection lens for forming a projection pattern image.

However, the pattern CP described above is
Since both ends are sharply pointed, for example, as shown in FIG.
As shown in (a), the length L _RP of the resist pattern _RP
Is 10 μm, the width of the center is 0.5 μm, and both ends are 0.1 μm.
When the size becomes about m, a part of the resist pattern RP corresponding to both ends of the pattern CP during development (FIG. 13B)
The broken line portion RP ′) of FIG.

This is because the thinned portion (RP ') of the resist pattern RP has weak adhesion to the underlying semiconductor wafer HW. In such a case, since the pattern CP cannot be faithfully reproduced in forming the resist pattern RP, for example, as shown in FIG. 13B, the actual length L _RP of the resist pattern RP is measured by the alignment detector. Between the measured value L _RP ′ and the measured value L _RP ′.

As described above, the inaccurate measurement of the actual length L _RP of the resist pattern RP makes it difficult to detect the optimum focus position of the projection lens for forming the resist pattern RP. there were.

Further, as described above, when the accuracy in forming the resist pattern RP is not guaranteed, the pattern RP may be erroneously recognized as a defect in a later reticle defect inspection.

[0021]

As described above, in the prior art, since the linear pattern used for calculating the optimum forming conditions has a sharp pointed shape at both ends, so-called pattern peeling easily occurs. When this pattern peeling occurs, the length of the resist pattern cannot be measured accurately, and as a result, there is a disadvantage that the optimum focus position of the projection lens for forming the resist pattern cannot be detected.

Accordingly, the present invention provides an exposure method for an exposure apparatus that can accurately calculate an exposure processing condition optimal for forming a projection pattern image and can control the exposure condition of the exposure apparatus with high accuracy. It is an object.

[0023]

In order to achieve the above object, in an exposure method of an exposure apparatus according to the present invention, an image is formed on a wafer by changing an exposure condition formed on a reticle. A first step of transferring a focus detection pattern having a shape easily affected by the optical proximity effect to the projected pattern image onto the wafer via a projection optical system, and forming the focus detection pattern on the wafer. A second step of calculating an optimum exposure processing condition for forming the projection pattern image from the projection pattern image of the focus detection pattern; and controlling the exposure condition based on the calculated optimum exposure processing condition. And a third step.

According to the exposure method of the exposure apparatus of the present invention, when a predetermined mask pattern formed on a reticle is projected and exposed on a wafer via a projection optical system, With the change of the defocus amount and the exposure amount, the projected pattern image formed on the wafer, a focus detection pattern of a shape easily affected by the optical proximity effect, via the projection optical system, A first step of transferring onto the wafer, and a correction of a defocus amount of the projection optical system that is at least optimal for forming the projection pattern image from a projection pattern image of the focus detection pattern formed on the wafer. A second step of calculating a value, a third step of adjusting a defocus amount of the projection optical system based on the calculated correction value, and a step of While adjusting the slag amount, a predetermined mask pattern formed on the reticle, through the projection optical system, it is made and a fourth step of the projection exposure onto the wafer.

According to the exposure method of the exposure apparatus of the present invention,
A focus detection pattern that is easily affected by the optical proximity effect is used for the projected pattern image formed on the wafer, so that a part of the projected pattern image is missing, so-called pattern peeling is prevented. become able to. As a result, the accuracy in forming the projection pattern image can be guaranteed, and the measurement can be performed accurately.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a step-and-repeat type reduction projection type light exposure apparatus (optical stepper) according to the present invention.

That is, the illumination light from the light source 11 is applied to a reticle (mask) R as a projection original via a condenser lens 21. Then, the projection image from the reticle R is reduced by a telecentric projection lens (projection optical system) 41 on both sides or one side and projected onto the wafer HW.

At this time, the exposed surface of the wafer HW is coated with a photoresist, and the resist is exposed by a reduced pattern image projected through the projection lens 41.

The light source 11 includes light effective for exposing the photoresist coated on the exposed surface of the wafer HW,
For example, a mercury lamp that emits g-line or i-line light is used.

On reticle R, for example, a circuit pattern (mask pattern) of a semiconductor integrated circuit element corresponding to the reduced pattern image is formed. A focus detection pattern (details will be described later) is provided on a non-forming area of the circuit pattern, for example, on a dicing line (scribe line).

The reticle R is mounted on a reticle stage 31 fixed on the optical axis of the illumination light. The reticle stage 31 is provided with an opening 31a larger than the circuit pattern on the reticle R for transmitting the projected image.

As the projection lens 41, for example, an optical system in which the reticle R side is non-telecentric and the wafer HW side is telecentric is used. The projection lens 41 is provided movably in the optical axis direction of the illumination light, for example, according to the setting of the projection magnification by a control system 61 described later.

On the exposure surface of the wafer HW, a photoresist which is easily exposed by the illumination light from the light source 11 is coated. The wafer HW is mounted on a wafer stage 51 that is movable in an X-axis direction and a Y-axis direction perpendicular to the optical axis direction of the illumination light, and in a Z-axis direction parallel to the optical axis direction of the illumination light. It has become so.

Movement of the wafer stage 51 in the X-axis direction,
The movement in the Y-axis direction and the movement in the Z-axis direction are controlled by the control system 61 via drive mechanisms in the respective axial directions (not shown).

The position of the wafer stage 51 in the Z-axis direction is detected by a laser interferometer 52, for example. Similarly, the position of the wafer stage 51 in the X-axis direction and the position in the Y-axis direction are also detected by a laser interferometer (not shown), and the respective outputs are supplied to the control system 61. I have.

Further, the optical stepper is provided with, for example, a dimension measuring device 71 also serving as an alignment detector for focusing the projected image from the reticle R on the exposure surface on the wafer HW with high accuracy. Have been.

The dimension measuring device 71 includes, for example, a lamp 71a capable of irradiating a spot light on a projection pattern image corresponding to a focus detection pattern formed on an exposure surface of a wafer HW, Converter 71 that detects reflected light (diffraction light or scattered light) due to light
b and a half mirror 71c for guiding the reflected light to the photoelectric converter 71b.

The control system 61 controls the overall control of the optical stepper. For example, in addition to turning on the light source 11, moving the projection lens 41, and moving the wafer stage 51, From the output of the photoelectric converter 71b of the dimension measuring device 71, in order to correct a positional shift (focus shift) from the focus position of the projection lens 41 as an exposure processing condition optimal for forming a reduced pattern image (resist pattern). Of the wafer stage 51 in the Z-axis direction according to the correction value while calculating the correction value (the defocus amount or the difference from the in-focus position) of the laser interferometer 52. (Exposure conditions).

The control system 61 controls the position of the wafer stage 51 in the X-axis direction and the Y-axis direction based on the output of the photoelectric converter 71b of the dimension measuring device 71, and controls the reticle R and the reticle R. Positioning (alignment) with the wafer HW is performed.

FIG. 2 shows an example of a focus detection pattern used for calculating the correction value. The focus detection pattern CPa is, for example, as shown in FIG. 3A, optically close to the projection pattern image RPa formed on the wafer HW due to the defocus of the projection lens 41 (change in exposure condition). It is a single rectangular pattern in which the corners, which are approximately 90 ° of a substantially square, are likely to be affected by the effect (the corners are rounded, so-called corner rounding phenomenon) and are arranged in the vertical and horizontal directions. .

In the case of the focus detection pattern CPa, for example, as shown in FIG. 3B, the roundness of the corner of the projection pattern image RPa gradually increases due to the defocus of the projection lens 41.

Accordingly, for example, as shown in FIG. 3C, the horizontal length Lx of the projection pattern image RPa
_{By calculating RPa} or length Ly _RPa in the vertical direction,
The amount of defocus with respect to the focus position for each defocus (correction value ΔF) can be accurately calculated.

Next, an exposure method according to an embodiment of the present invention will be briefly described with an optical stepper having the above configuration as an example. At the time of exposure, for example, the light source 11 and the wafer stage 51 are driven by the control system 61 for each shot, and the circuit pattern of the element formed on the reticle R is projected via the projection lens 41. A reduced pattern image corresponding to the circuit pattern is transferred.

Then, by repeating the projection of the circuit pattern while changing the position of the wafer HW, the reduced pattern image is transferred in a matrix by a step-and-repeat method on the exposure surface of the wafer HW.

At this time, the control system 61 calculates a correction value ΔF for correcting a defocus from the focus position of the projection lens 41 based on the measurement result of the dimension measuring device 71 and corrects the correction value. The position of the wafer stage 51 in the Z-axis direction is controlled according to the value ΔF.

The position of the wafer stage 51 in the X-axis direction and the Y-axis direction is controlled based on the measurement result of the dimension measuring device 71, and the reticle R and the wafer HW are aligned.

That is, for example, two opposing corners of the projection pattern image RPa of the focus detection pattern CPa formed on the reticle R transferred onto the wafer HW with the exposure of the circuit pattern. The length (size length) between them is measured by the dimension measuring device 71, and the result is taken in as the output of the photoelectric converter 71b.

[0048] Then, the projection pattern from the measurement result, for example, with determining the horizontal length Lx _RPa of the projected pattern image RPa, the horizontal direction indexing the length Lx _RPa, the focus position of the projection lens 41 Statue RP
The actual defocus amount of the projection lens 41 is obtained by comparing the length with the length a (design value or the like), and is calculated as a correction value ΔF.

Further, while checking the output from the laser interferometer 52, the position of the wafer stage 51 in the Z-axis direction is controlled according to the correction value ΔF, and the defocus from the focus position of the projection lens 41 is controlled. to correct.

[0050] Also, at that time, for example, as shown in FIG. 3, the output O ₇₁ of the photoelectric converter 71b, a projection pattern image RPa of the focus detection pattern CPa, known provided on the wafer HW Of the alignment mark (1st mark of the bar-in-bar) AM is calculated.

Then, the position of the wafer stage 51 in the X-axis direction is controlled so as to correct the positional deviation amount ΔLx, and similarly, the position of the wafer stage 51 in the Y-axis direction is controlled. And the above wafer HW
And position.

In this way, while correcting the defocus from the focus position of the projection lens 41 and aligning the reticle R with the wafer HW, the circuit pattern formed on the reticle R is adjusted. ,
By repeatedly projecting the wafer HW onto the exposure surface by the step-and-repeat method, the exposure process by the optical stepper is always performed under the optimal exposure condition.

As described above, the occurrence of so-called pattern peeling, in which a part of the projected pattern image of the focus detection pattern for detecting the focus shift from the focus position of the projection lens is lost, can be prevented.

That is, a rectangular pattern which is likely to be affected by the optical proximity effect is used as a focus detection pattern in a projection pattern image formed on a wafer. As a result, the projection pattern image by the focus detection pattern can be faithfully reproduced, so that the accuracy in forming the projection pattern image can be guaranteed. Therefore, it is possible to accurately calculate the optimum focus position (defocus amount) of the projection lens for forming the projection pattern image without using expensive measuring equipment, and to control the exposure condition of the exposure apparatus with high accuracy. It becomes.

In particular, since the focus detection pattern is formed on the reticle for the circuit, the defocus of the projection lens can be corrected in parallel with the exposure process without requiring the development process. The transfer of the pattern can always be performed under the optimal exposure condition.

Moreover, by using the projected pattern image of the focus detection pattern as the second mark in the bar-in-bar type alignment mechanism, it is possible to easily correct the defocus and simultaneously align the reticle and the wafer. It is possible.

Further, since the accuracy in forming the projection pattern image can be ensured, it is also possible to reduce the erroneous recognition of the pattern image as a defect in the later reticle defect inspection.

In the embodiment of the present invention described above, the case where the defocus of the projection lens is corrected based on the horizontal length _LxRPa of the projection pattern image of the focus detection pattern. I explained, but not limited to this,
For example, the present invention can be similarly implemented by using the length Ly _{RPa of the} projection pattern image in the vertical direction, and when the correction is made based on the lengths in both the vertical and horizontal directions, the length can be changed in any one direction. Control with higher accuracy than in the case of correction can be performed.

Also, after correcting the defocus of the projection lens in advance using a correction reticle provided with only the focus detection pattern, the circuit pattern is exposed using the circuit reticle. good.

Further, the correction of the defocus of the projection lens is not limited to the case where the position of the wafer stage is controlled.
It is also possible to correct by directly controlling the position of the projection lens.

Regarding the exposure conditions, it is also possible to correct the defocus of the projection lens regardless of the exposure amount, for example, to correct the defocus of the projection lens while keeping the exposure amount constant. Alternatively, the exposure amount can be adjusted while the projection lens is kept at the focal position.

As a dimension measuring device, for example,
The projection pattern image of the focus detection pattern may be measured without using a projection lens, or an electron beam may be used.

Further, the focus detection pattern is not limited to a single pattern consisting of one rectangular pattern having a substantially square shape. For example, as shown in FIG. 4, a plurality of single patterns (a plurality of rectangular patterns) are formed. It is also possible to configure by the second configuration example).

FIG. 9A shows two rectangular patterns cp.
Focus detection pattern C in which ₁ and cp ₂ are arranged in the horizontal direction
Pb, in this case, two rectangular patterns c
When the exposure condition is controlled such that the total length (La _RPb ) of the projection pattern images (RPb) of p ₁ and cp ₂ is maximum and the interval length (Lb _RPb ) between the projection pattern images is minimum. In this case, it is possible to perform measurement with a dimension measuring apparatus with a high sensitivity of about √2 (route 2) of the above exposure method.

FIG. 7B shows n rectangular patterns cp.
₁ , cp ₂ ,..., Cp _n indicate the focus detection patterns CPb ′ arranged in the horizontal direction. In this case, when the exposure condition is controlled in the same manner, It becomes possible to perform measurement by a dimension measuring device with a high sensitivity of about Δn (route n) times the exposure method.

Further, the focus detection pattern may be constituted by an aggregate pattern formed by arbitrarily combining a plurality of rectangular patterns. FIG. 5 shows, for example, a focus detection pattern (third configuration example) CP in which a plurality of rectangular patterns cp are continuously arranged in large and small rectangular frames.
In this case, the horizontal length (Lx _RPc (or vertical length (Ly _RPc ))) of one of the projection pattern images and the vertical length of the other projection pattern image (Ly _RPc (or lateral length (Lx _RPc ))) (or either one)
By controlling the exposure conditions to maximize
Almost the same effects as the above-described exposure method can be expected.

[0067] Incidentally, for example, as shown in FIG. 6, one of the pattern image RPc ₁ or other pattern image RPc ₂ of the projected pattern image RPc, as utilized as a 1st mark or 2nd mark in the alignment mechanism of the bar Invar type Focus detection pattern (CPc ')
As described above, simultaneously with the correction of the defocus of the projection lens, the alignment between the reticle and the wafer (the amount of lateral displacement ΔLx and the amount of vertical displacement ΔL
Ly calculation) can also be easily performed.

FIG. 7 shows, for example, a focus detection pattern (fourth configuration) in which a plurality of rectangular patterns cp are continuously arranged in the vertical and horizontal directions without gaps so that the vertical and horizontal directions are respectively line-symmetric. Example) CPd, in which case the horizontal length (Lx _RPd ) and the vertical length (Ly _RPd ) of the projected pattern image ( _RPd ) are both maximum (or one of them). By controlling the exposure conditions so as to satisfy the above, substantially the same effects as in the above-described exposure method can be expected.

FIG. 8 shows, for example, a certain direction (here,
A focus detection pattern (fifth configuration example) CP in which a plurality of rectangular patterns cp are continuously arranged in the vertical and horizontal directions without gaps so as to be line-symmetric with respect to a diagonal line from the upper left to the lower right.
In this case, the horizontal length (Lx) from the outward corner portion (o) to the inward corner portion (i) in the projected pattern image (RPe).
_By controlling the exposure conditions so that both ( _RPe ) and the length (Ly _RPe ) in the vertical direction (or any one of them) are maximized, substantially the same effect as the above-described exposure method can be expected. .

The focus detection pattern C shown in FIG.
Pd and the focus detection pattern CPe shown in FIG.
In addition to the case where each of them is configured as a single pattern, for example, as shown in FIG. 4, it is also possible to arrange several patterns to form one focus detection pattern.

FIG. 9 shows, for example, as a focus detection pattern (sixth configuration example) CPf, one set pattern CPfa in which a plurality of rectangular patterns cp are continuously arranged at least in the vertical direction, and a light proximity effect CPf. This is an example in which a rectangular pattern CPfb, which is less likely to have an effect, is configured to be opposed to the rectangular pattern CPfb.

In this case, the rectangular pattern CPfb
Since the degree of pattern deformation at the time of defocusing is small, it is easy to calculate the distance from the aggregate pattern CPfa. As a result, the interval length (L _RPf ) of the focus detection pattern CPf in the projection pattern image ( _RPf ) By controlling the exposure conditions so that is minimized, substantially the same effect as the above-described exposure method can be expected.

In each of the above-described focus detection patterns, a case where each of the focus detection patterns is formed using a substantially square-shaped rectangular pattern has been described. However, a rectangular pattern having another shape (angle) is used. It is also possible to configure.

Further, as a focus detection pattern having a shape that is likely to be affected by the optical proximity effect, for example, FIG.
0, as shown in FIG.
Focus detection pattern (seventh configuration example) having a structure in which the tip of a sharper corner portion is divided into a plurality of portions CP
It can also be constituted by g.

In this case, the focus detection pattern CPg is
Projection pattern image (RPg) due to change in exposure conditions
In this case, the length of the projected pattern image (L _RPg ) can be accurately measured because the leading end of the pattern becomes short, that is, the occurrence of the so-called pattern shortening phenomenon can be suppressed. Almost the same effect can be expected.

Similarly, for example, as shown in FIG. 11, when a focus detection pattern (eighth configuration example) CPh having a structure in which the tip end of a rectangular rectangular pattern cpb is divided into a plurality of parts, The length (L _RPh ) of the projected pattern image (RPh) can be accurately measured, and a sufficient effect can be expected.

The focus detection pattern CPg shown in FIG. 10 and the focus detection pattern CPh shown in FIG.
Are each configured as a single pattern,
For example, several patterns can be arranged side by side to form one focus detection pattern. Others
Of course, various modifications can be made without departing from the scope of the present invention.

[0078]

As described in detail above, according to the present invention, it is possible to accurately calculate an exposure processing condition optimal for forming a projection pattern image, and to control an exposure condition of an exposure apparatus with high accuracy. An exposure method for an exposure apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a step-and-repeat type reduction projection type light exposure apparatus according to the present invention.

FIG. 2 is a schematic diagram of a focus detection pattern shown to explain an operation according to the embodiment of the present invention.

FIG. 3 is a schematic view similarly illustrating an alignment operation between a reticle and a wafer using a focus detection pattern.

FIG. 4 is a schematic diagram showing another configuration example (second configuration example) of the focus detection pattern.

FIG. 5 is a schematic diagram showing another configuration example (third configuration example) of the focus detection pattern.

FIG. 6 is a schematic diagram for explaining an alignment operation when a focus detection pattern as a third configuration example is used.

FIG. 7 is a schematic diagram showing another configuration example (fourth configuration example) of the focus detection pattern.

FIG. 8 is a schematic diagram showing another configuration example (fifth configuration example) of the focus detection pattern.

FIG. 9 is a schematic diagram showing another configuration example (sixth configuration example) of the focus detection pattern.

FIG. 10 is a schematic diagram showing another configuration example (seventh configuration example) of the focus detection pattern.

FIG. 11 is a schematic diagram showing another configuration example (eighth configuration example) of the focus detection pattern.

FIG. 12 is a schematic diagram of a linear pattern shown to explain a conventional technique and its problems.

FIG. 13 is a schematic view showing a conventional linear pattern.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Light source 21 ... Condenser lens 31 ... Reticle stage 31a ... Opening 41 ... Projection lens 51 ... Wafer stage 52 ... Laser interferometer 61 ... Control system 71 ... Dimension measuring device 71a ... Lamp 71b ... Photoelectric converter 71c ... Half mirror AM: alignment marks CPa, CPb, CPb ', CPc, CPd, CPe,
CPf, CPg, CPh ... focus detection pattern _{cp, cp 1, cp 2,} cp 3, cp n ... rectangular pattern cpa ... rhombic rectangular pattern cpb ... rectangular rectangular pattern CPfa ... collective pattern CPfb ... Rectangular Jo pattern HW ... wafer R ... reticle _{RPa, RPc, RPc 1, RPc} 2 ... projected pattern image

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Kazuo Tawarayama 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Inside the Toshiba Yokohama office

Claims (24)

[Claims] 1. A projection optical system according to claim 1, wherein a projection pattern image formed on a reticle and formed on a wafer with a change in exposure conditions is provided with a focus detection pattern having a shape easily affected by an optical proximity effect. A first step of transferring onto the wafer via a system, and calculating an optimum exposure processing condition for forming the projection pattern image from a projection pattern image of the focus detection pattern formed on the wafer. An exposure method for an exposure apparatus, comprising: a second step; and a third step of controlling the exposure condition based on the calculated optimal exposure processing condition. 2. The exposure apparatus according to claim 1, wherein the focus detection pattern is a rectangular pattern in which a corner portion of the projection pattern image is rounded according to a change in exposure conditions. Method. 3. The exposure method according to claim 1, wherein the focus detection pattern is a single pattern including one rectangular pattern. 4. The exposure method according to claim 1, wherein the focus detection pattern is composed of a plurality of single patterns. 5. The exposure method according to claim 1, wherein the focus detection pattern is an aggregate pattern formed by combining a plurality of rectangular patterns. 6. The exposure method according to claim 1, wherein the focus detection pattern comprises a plurality of aggregated patterns. 7. The exposure apparatus according to claim 1, wherein the focus detection pattern comprises the aggregate pattern and a pattern having a shape that is hardly affected by an optical proximity effect. Exposure method. 8. The exposure apparatus according to claim 1, wherein a predetermined mask pattern projected and exposed on the wafer is formed on the reticle via the projection optical system. Method. 9. The method according to claim 2, wherein the second step is to calculate an optimum exposure processing condition for forming the projection pattern image from a size length of the projection pattern image of the focus detection pattern. Item 6. An exposure method of the exposure apparatus according to Item 1. 10. The method according to claim 1, wherein the second step calculates an exposure processing condition optimal for forming the projection pattern image from an interval length between the projection pattern images of the focus detection pattern. An exposure method for the exposure apparatus according to claim 1. 11. The exposure method according to claim 1, wherein the third step adjusts a defocus amount of the projection optical system. 12. The first, second, and third steps are performed when the mask pattern formed on the reticle is projected and exposed on the wafer via the projection optical system. The exposure method of the exposure apparatus according to claim 1, wherein: 13. In the first, second and third steps, the mask pattern of the reticle on which a predetermined mask pattern is formed is projected and exposed on the wafer via the projection optical system. 2. The exposure method according to claim 1, wherein the exposure is performed before the exposure. 14. A step of calculating an amount of misalignment between the position of the reticle and the position of the wafer using a projection pattern image of the focus detection pattern formed on the wafer, and the calculated misalignment. Adjusting the position of the wafer with respect to the reticle according to an amount. 15. An exposure method of an exposure apparatus for projecting and exposing a predetermined mask pattern formed on a reticle onto a wafer via a projection optical system, wherein a change in a defocus amount and a change in the exposure amount formed on the reticle. A first pattern for transferring a focus detection pattern having a shape easily affected by the optical proximity effect to the projection pattern image formed on the wafer via the projection optical system onto the wafer. And a second step of calculating, from the projection pattern image of the focus detection pattern formed on the wafer, at least a correction value of a defocus amount of the projection optical system that is optimal for forming the projection pattern image. A third step of adjusting a defocus amount of the projection optical system based on the calculated correction value; and A predetermined mask pattern formed on a serial reticle via the projection optical system, an exposure method for an exposure apparatus characterized by comprising a fourth step of the projection exposure onto the wafer. 16. The pattern according to claim 15, wherein the focus detection pattern is a rectangular pattern in which a corner portion of the projected pattern image is rounded with a change in the defocus amount and the exposure amount. Exposure method of exposure apparatus. 17. The exposure method according to claim 15, wherein the focus detection pattern is a single pattern composed of one rectangular pattern. 18. The focus detection pattern according to claim 15, wherein the focus detection pattern comprises a plurality of single patterns.
Or the exposure method of the exposure apparatus according to any one of the above items 17. 19. The exposure method according to claim 15, wherein the focus detection pattern is an aggregate pattern formed by combining a plurality of rectangular patterns. 20. The focus detection pattern according to claim 15, wherein the focus detection pattern comprises a plurality of aggregate patterns.
Or the exposure method of the exposure apparatus according to any one of the above items 19. 21. The exposure apparatus according to claim 15, wherein the focus detection pattern comprises the aggregate pattern and a pattern having a shape that is less likely to be affected by the optical proximity effect. Exposure method. 22. The second step of calculating a correction value of a defocus amount of the projection optical system optimal for forming the projection pattern image from a size length of the projection pattern image of the focus detection pattern. 2. The method according to claim 1, wherein
6. The exposure method of the exposure apparatus according to 5. 23. In the second step, a correction value of a defocus amount of the projection optical system that is optimal for forming the projection pattern image is calculated from an interval length between the projection pattern images of the focus detection pattern. 2. The method according to claim 1, wherein
6. The exposure method of the exposure apparatus according to 5. 24. A step of calculating an amount of misalignment between the position of the reticle and the position of the wafer using a projection pattern image of the focus detection pattern formed on the wafer, and the calculated misalignment. Adjusting the position of the wafer with respect to the reticle according to an amount.