JPH0737774A - Scanning aligner - Google Patents

Abstract

PURPOSE:To accurately correct exposure nonuniformity, by changing intensity distribution relative to a first direction of an exposure beam formed by a stop means capable of changing the aperture width relative to a second direction at a plurality of points along the first direction. CONSTITUTION:An exposure nonuniformity detecting circuit 19 controls electric power inputted in a lamp 1 according to the detection result of a first light quantity detector 18, and keeps the illuminance of (the whole) illumination region 90 of a reticle 12 to be a constant value. A second light quantity detector 17 is made to scan an illumination region 100 (the image of the region 90) by moving a wafer stage 16, and detects the illumination distribution of the illumination region 100. The exposure nonuniformity detecting circuit 19 detects exposure nonuniformity which is to be generated on a wafer 14, on the basis of the detection result of the light quantity detector 17. The output from the exposure nonuniformity detecting circuit 19 restrains exposure nonuniformity of the illumination region 100 clue to an illuminance distribution changing lens 7 and a viable slit 9 to a minimum via an exposure nonuniformity correcting circuit 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type exposure apparatus, especially I
The present invention relates to a scanning exposure apparatus used for manufacturing semiconductor devices such as C and LSI, imaging devices such as CCDs, display devices such as liquid crystal panels, and various devices such as magnetic heads.

[0002]

2. Description of the Related Art High integration and fine pattern of semiconductor devices
As manufacturing progresses, a slight change in the manufacturing process has led to a decrease in yield due to an increase in the defect rate.

Particularly, in a scanning type exposure apparatus for projecting a pattern on a mask onto a wafer by relatively scanning the mask and the wafer with respect to a slit-shaped light beam, the slit length direction ( Exposure unevenness in the direction perpendicular to the scanning direction of the slit-shaped light flux increases the defect rate in manufacturing semiconductor devices.

[0004]

FIG. 10A shows a state in which a plurality of element patterns are sequentially scanned and exposed within the wafer 14, and the hatched portion in the drawing indicates a certain time. This is the exposed area. The element pattern is exposed by repeating scanning and steps in this exposure area as shown by the arrow. In such an exposure method, as shown in FIG.
The exposure unevenness within one shot 14a (the range exposed by one scan) shown enlarged in FIG. 8B is almost uniform in the x direction (direction parallel to the scanning direction) as shown in FIG. 8C. However, in the y direction (direction perpendicular to the scanning direction), unevenness in the light intensity distribution of the slit-shaped light beam itself and unevenness in the exposure amount due to the difference in the slit width depending on the location occur.

To correct the exposure unevenness on the wafer during scanning exposure, as disclosed in Japanese Patent Laid-Open No. 62-193125, the width of the slit is partially changed and the exposure amount of each portion is changed. There is a way to adjust. FIG. 11 shows an example of slits with variable slit width in a scanning type exposure apparatus that performs scanning exposure with a ring-shaped light beam. The slit is composed of a large number of light shielding members, and the plurality of light shielding members are independently moved to adjust their positions, thereby partially changing the width of the slit. In this method, a large number of movable light-shielding members are required in order to suppress uneven exposure, resulting in a complicated mechanism.

On the other hand, as disclosed in JP-A-61-267722, there is also a method of changing the illuminance distribution by moving a plurality of lenses in the illumination optical system in the optical axis direction. 12 and 13 show a plurality of such lenses,
The change in the illuminance distribution due to the movement in the optical axis direction is shown. In FIG. 13, the horizontal axis represents the position on the illuminated surface (distance from the optical axis), and the vertical axis represents the illuminance at each position (off-axis) when the illuminance on the optical axis (center) is 1. Shows. Figure 1
In the case of the lens position shown in FIG. 2 (A), the illuminance distribution is as shown in FIG. 13 (a), and in the case of the lens position shown in FIG. 12 (B), it is as shown in FIG. 13 (b). The illuminance distribution is stable. In this example, the illuminance distributions (a) and (b) in FIG. 13 are made extreme distributions, and the illuminance distribution can be continuously changed within the shaded area in FIG. 13 depending on the lens position.

However, the change of the illuminance distribution changes with a quadratic curve or a curve close to the quadratic curve with respect to the reference as shown in a to e of FIG. 14, and the illuminance is corrected at a certain image height. Once the amount has been determined, the correction amount of the illuminance at other image heights is also uniquely determined. For example, by moving the lens,
Even if the illuminance distribution shown in FIG. 5 (A) can be corrected uniformly as shown in FIG. 15 (B), the illuminance distribution shown in FIG. 15 (C) may be corrected only to the extent shown in FIG. 15 (D).

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a scanning type exposure apparatus capable of accurately correcting exposure unevenness.

In order to achieve the above-mentioned object, the scanning exposure apparatus of the present invention has a second exposure beam which intersects the first direction with an exposure beam having a cross-sectional shape extending in the first direction through the mask and the substrate to be exposed.
In the apparatus for sequentially projecting the pattern of the mask on the substrate to be exposed by scanning in the direction of
A plurality of openings along the first direction, and the width of the opening in the second direction can be changed at a plurality of locations along the first direction.
It has diaphragm means for forming the exposure beam, and intensity distribution changing means for changing the intensity distribution of the exposure beam in the first direction.

In a preferred form of the scanning type exposure apparatus of the present invention, the intensity of the exposure beam in the first direction is provided with a photodetector or the like having a slit-shaped opening that moves along the first direction. A means for detecting the distribution is provided.

In a preferred form of the scanning type exposure apparatus of the present invention, the diaphragm means includes at least two light shielding members that define edges of both ends of the exposure beam in the first direction, and the exposure beam. And at least one light blocking member that defines an edge on one side in the second direction, and at least two light blocking members that define an edge on the other side in the second direction of the exposure beam. There is provided means for changing the angle of the edges of the two light shielding members defining the edge on the other side of the exposure beam in the second direction with respect to the first direction.

In one mode of the scanning type exposure apparatus of the present invention, the intensity distribution changing means includes a plurality of lenses that are movable in the optical axis direction.

In one mode of the scanning type exposure apparatus of the present invention, the intensity distribution changing means is provided with a plurality of optical elements having different transmittance characteristics coated with different transmittances depending on the incident angle of a light beam. By arranging a desired optical element of the plurality of optical elements in the vicinity of the pupil plane of the system, the intensity distribution of the exposure beam can be changed, and along with this, it can be moved in the optical axis direction. It is equipped with multiple lenses.

By using the scanning type exposure apparatus of the present invention, various devices such as semiconductor devices such as IC and LSI, imaging devices such as CCD, display devices such as liquid crystal panels, magnetic heads, etc. can be manufactured accurately with good yield. It will be possible.

[0015]

1 is a schematic view showing an embodiment of the present invention, in which semiconductor devices such as IC and LSI, image pickup devices such as CCD, display devices such as liquid crystal panels, and various devices such as magnetic heads are manufactured. 1 shows a scanning projection exposure apparatus for. Reference numeral 1 denotes a light source that emits ultraviolet rays such as an ultra-high pressure mercury lamp, and 1a denotes a light emitting portion of the light source 1. Reference numeral 2 denotes an elliptical mirror. The light emitting portion 1a of the light source 1 is arranged in the vicinity of the first focus of the elliptical mirror-2, and the light flux emitted from the light emitting portion 1a is condensed at the second focus 3 of the elliptical mirror-2. , The light emitting portion image 1b is formed at the second focal point 3. The light from the light emitting portion image 1b at the second focus 3 is condensed on the light incident surface of the fly-eye lens 6 which is an optical integrator via the condenser lens 4 and the mirror 5, and the fly-eye lens 6 emits light. Light exit surface 6
A plurality of secondary light sources are formed near a. 7 is a reticle 12
Is a condenser lens (variable illuminance distribution variable lens) having a function of changing the illuminance distribution above, and the lens 7 has an aperture width of light fluxes from a plurality of secondary light sources formed on the light exit surface 6 a of the fly-eye surface lens 6. To the variable slit 9 that can change
The variable slit 9 is illuminated with a cable. The variable slit 9 and the reticle 12 are arranged at optically conjugate positions via the imaging lens and the mirror 11, and the opening of the variable slit 9 forms an image on the device pattern forming surface of the reticle 12. Therefore, the size / shape of the opening of the variable slit 9 determines the size / shape of the illumination region 90 in the reticle 12. Reference numeral 13 denotes a projection optical system including a refracting optical system, a catadioptric optical system, and the like, which projects the device pattern of the reticle 12 onto the wafer 14. 15 is a wafer chuck,
16 is a wafer stage. The reticle 12 and the wafer 14 are synchronously moved in a predetermined scanning direction by a corresponding driving device (not shown) at a speed ratio according to the magnification of the projection optical system 13. At this time, the device of the reticle 12 is moved. The device pattern of the reticle 12 is transferred onto the wafer 14 as the pattern crosses the illumination area 90.

Reference numeral 18 denotes a light quantity detector, which is a half mirror-8.
Due to this, a part of the exposure light that defines the illumination area 90 is received and the intensity is detected. The uneven exposure detection circuit 19 includes a light amount detector 18
The electric power input to the lamp 1 is controlled on the basis of the detection result of 1. to maintain the illuminance of the illumination area 90 (entire) of the reticle 12 at a constant value. Reference numeral 17 denotes a second light amount detector, which is mounted on the wafer stage 16 (another stage).
Sometimes placed on the). The light amount detector 17 moves the wafer stage 16 to move the illumination area 10
0 (the image of the area 90) and the illuminated area 10 is scanned.
The illuminance distribution within 0 is detected. The uneven exposure detection circuit 19 detects uneven exposure that may occur when the wafer 14 is exposed, based on the detection result of the light amount detector 17. The output from the exposure unevenness detection circuit 19 causes the exposure unevenness correction circuit 20 to perform an operation of minimizing the exposure unevenness of the illumination region 100 by the illuminance distribution variable lens 7 and the variable slit 9.

The exposure unevenness detecting method and the exposure unevenness correcting method in the apparatus of FIG. 1 will be described in detail below.

The unevenness of exposure is detected by using the light quantity detector 17 mounted on the wafer stage 16 as described above. Among the illuminance distributions of the illumination area 100 on the shot of the wafer-14, the unevenness of the illuminance distribution in the scanning direction has a small effect on the exposure unevenness. Therefore, here, the exposure unevenness is obtained by measuring the distribution of the integrated value of the illuminance distribution in the scanning direction in the direction orthogonal to the scanning direction (corresponding to the longitudinal direction of the opening of the slit 9). First, in order to measure the integrated value of the illuminance (light intensity) distribution in the scanning direction, the light amount detector 17
The light incident on is limited by a diaphragm longer than the illumination area 10 in the scanning direction, such as the slit 30 in FIG. 5, and is reduced by a light beam entering the light quantity detector 17 through this diaphragm (or an ND filter after passing through the diaphragm). (Light flux emitted) is detected photoelectrically, the light quantity detector 17 with a slit-like diaphragm is moved in a direction orthogonal to the scanning direction, and detection is repeated, and illuminance at each position along the orthogonal direction. Detect the integrated value of distribution. Instead of scanning the slit-shaped diaphragm in the direction orthogonal to the scanning direction to detect the exposure unevenness, the pinhole is scanned in the scanning direction and in the direction orthogonal to the scanning direction, and the direction orthogonal to the scanning direction (of the slit 9). The uneven exposure may be detected by measuring the distribution of the integrated value of the illuminance distribution in the scanning direction (corresponding to the longitudinal direction of the opening).

The exposure unevenness is corrected by using the illuminance distribution variable lens 7 and the variable slit 9. Variable slit 9 of FIG.
As shown in FIG. 2, five blades (light shielding plates) 9a to 9e are provided.
2A, 2B, and 2C, by changing the angle of the edges of the movable blades 9a and 9b with respect to the scanning direction, the direction along the direction orthogonal to the scanning direction is provided. The slit width at each position is changed linearly. For example, the angles θ _{1 of} the blades 9a and 9b with respect to the scanning direction,
θ ₂ is θ ₁ = θ ₂ = 90 as shown in FIG. In this case, the exposure amount distribution in the direction orthogonal to the scanning direction becomes uniform as shown in FIG. 3 (a), and the angles θ ₁ and θ ₂ are shown in FIG.
As shown in (B), θ ₁ = θ ₂ <90. At this time, the exposure amount distribution in the direction orthogonal to the scanning direction becomes the distribution shown in FIG. 3B, and the angles θ ₁ and θ ₂ are θ ₁ = θ ₂ > 90 as shown in FIG. 2C. In the case of, the exposure amount distribution in the direction orthogonal to the scanning direction becomes the distribution as shown in FIG. By changing the angles of the edges of the blades 9a and 9b of the variable slit 9 with respect to the scanning direction in this manner, the exposure amount distribution in the direction orthogonal to the scanning direction is changed as shown in FIG. The variable illuminance distribution lens 7 is disclosed in, for example, Japanese Patent Laid-Open No. 61-26772.
The illuminance distribution of the illumination regions 90 and 100 can be changed along a certain curve as shown in FIG. 13 by the lens system disclosed in Japanese Patent Publication No. Can be changed.

FIG. 4 is an explanatory view showing a method of correcting the exposure unevenness by the variable illuminance distribution lens 7 and the variable slit 9, and a state of correcting the exposure unevenness in the y direction orthogonal to the scanning direction shown in FIG. 4 (A). Is shown. FIG. 4B shows how the illuminance distribution variable lens 7 changes the curved non-uniform exposure amount distribution of FIG. 4A into a linear distribution, and FIG. 4 (B) shows how a linear non-uniform exposure amount distribution is converted into a uniform exposure amount distribution.

By using the two exposure unevenness correcting means in this way, it is possible to minimize the exposure unevenness in the direction orthogonal to the scanning direction. The amount of movement of the movable lens of the variable illuminance distribution lens 7 in the direction of the optical axis and the tilt angle of the movable blade of the variable slit 9 when performing this correction are uniquely determined in advance by calculation in accordance with the exposure unevenness. You can
The exposure amount distribution may be optimized by repeatedly detecting and correcting the exposure unevenness using the light amount detector 17, etc., the illuminance distribution variable lens 7, and the variable slit 9.

FIG. 6 shows another embodiment of means for correcting uneven exposure. In this embodiment, an optical element 30a having a transparent parallel plane plate coated with a different transmittance depending on the incident angle of the light beam is arranged near the light exit surface 6a of the fly-eye lens 6 in the illumination optical system. , A desired optical element is selectively arranged from the plurality of optical elements (30a, 30b, ...) Having different characteristics in the vicinity of the light exit surface 6a to change the illuminance distribution on the wafer-14. FIG. 7 shows an exposure dose distribution when different optical elements are selectively arranged near the light exit surface 6a. This optical element may be used in combination with the variable slit 9 and the illuminance distribution variable lens 7, or may be used only with the variable slit 9.

Further, in the above embodiment, the angles θ ₁ and θ ₂ of the blades 9a and 9b of the variable slit 9 are θ ₁ = θ ₂
However, this is not always necessary. For example, when there is asymmetric exposure unevenness in the direction orthogonal to the scanning direction of the wafer 14, θ ₁ ≠ θ ₂ may be set.
Further, the movable blade of the variable slit 9 is not limited to the two blades 9a and 9b as shown in FIG. 2, and for example, three or four movable blades can be supplied. The angles may be set independently of each other.

In the above embodiment, an ultrahigh pressure mercury lamp is used as the light source, but as the light source, for example, an excimer lamp is used.
A laser such as a laser can also be used.

Next, an embodiment of a method of manufacturing a semiconductor device using the scanning projection exposure apparatus of FIG. 1 will be described. FIG. 8 shows a manufacturing flow of a semiconductor device (semiconductor chip such as IC or LSI, liquid crystal panel or CCD). In step 1 (circuit design), the circuit of the semiconductor device is designed. Step two
In (mask manufacturing), a mask (reticle 304) on which the designed circuit pattern is formed is manufactured. On the other hand, step 3
In (wafer-manufacturing), a wafer (wafer-306) is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique using the mask and the wafer prepared above. The next step 5 (assembly) called a post-process, Step 4 thus wafer created - a step of chip the, assembly process (dicing, Bonde _b ring), package - managing step (chip encapsulation) Etc. are included. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7).
To be done.

FIG. 9 shows a detailed flow chart of the wafer process. In step 11 (oxidation), the surface of the wafer (wafer 306) is oxidized. Step 12 (CV
In D), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 15 (resist processing)
Then, a resist (sensitive material) is applied to the wafer. In step 16 (exposure), the projection exposure apparatus exposes the wafer with an image of the circuit pattern of the mask (reticle 304). In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist are scraped off. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, a circuit pattern is formed on the wafer.

By using the manufacturing method of this embodiment, it becomes possible to manufacture a highly integrated semiconductor device, which has been difficult in the past.

[0028]

As described above, according to the present invention, exposure unevenness can be accurately corrected.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the configuration and function of the variable slit shown in FIG.

FIG. 3 is a diagram showing how the exposure amount distribution is changed by the variable slit shown in FIG.

FIG. 4 is an explanatory diagram showing a manner of correcting exposure unevenness using the variable illuminance distribution lens and the variable slit shown in FIG. 1;

FIG. 5 is an explanatory diagram for explaining a method of detecting an exposure amount distribution.

FIG. 6 is a diagram showing another embodiment of means for correcting uneven exposure.

FIG. 7 is a diagram showing how the exposure amount distribution is changed by the correction means in FIG.

FIG. 8 is a diagram showing a manufacturing flow of a semiconductor device.

FIG. 9 is a diagram showing the wafer process of FIG. 8;

FIG. 10 is an explanatory diagram showing a state of scanning exposure.

FIG. 11 is a diagram showing an example of a variable slit.

FIG. 12 is a diagram showing an example of a configuration of an illuminance distribution variable lens.

FIG. 13 is an explanatory diagram showing a change in illuminance distribution by the illuminance distribution variable lens.

FIG. 14 is another explanatory diagram showing changes in the illuminance distribution by the illuminance distribution variable lens.

FIG. 15 is an explanatory diagram showing correction of uneven illuminance by a variable illuminance distribution lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mercury lamp 2 Elliptical mirror 4 Condenser lens 6 Fly-eye lens 7 Illuminance distribution variable lens 9 Variable slits 9a, 9b Movable blade 10 Imaging lens 12 Reticle 13 Projection optical system 14 Wafer 15 Wafer chuck 16 Wafer stage -17, 18 Light amount detector 19 Exposure unevenness detection circuit 20 Exposure unevenness correction circuit 30a, 30b Illuminance distribution variable element

Claims (9)

[Claims] 1. The pattern of the mask is scanned by scanning the mask and the substrate to be exposed with an exposure beam having a cross-sectional shape extending in the first direction in a second direction intersecting the first direction. A scanning type exposure apparatus for sequentially projecting onto an exposure target substrate, comprising: an opening extending in the first direction, wherein the width of the opening in the second direction can be changed at a plurality of locations along the first direction. A scanning exposure apparatus comprising: a diaphragm means for forming a beam; and an intensity distribution changing means for changing an intensity distribution of the exposure beam in the first direction. 2. The scanning exposure apparatus according to claim 1, further comprising means for detecting an intensity distribution of the exposure beam in the first direction. 3. The scanning exposure apparatus according to claim 1, wherein the intensity distribution changing unit includes a plurality of lenses that are movable in the optical axis direction. 4. The intensity distribution changing means comprises a plurality of optical elements having different transmittance characteristics coated with different transmittances depending on the incident angle of a light beam, and the plurality of optical elements among the plurality of optical elements are provided. 4. The scanning exposure apparatus according to claim 1, wherein the intensity distribution of the exposure beam is changed by disposing a desired optical element near the pupil plane of the system. 5. The diaphragm means includes at least two light-shielding members that define edges of both ends of the exposure beam in the first direction, and one edge of the exposure beam in one side of the second direction. 2. The scanning type exposure apparatus according to claim 1, further comprising at least one light-shielding member that defines an edge of the exposure beam, and at least two light-shielding members that define an edge of the exposure beam on the other side in the second direction. . 6. The device according to claim 5, further comprising means for changing an angle of the edges of the two light shielding members defining the other side edge of the exposure beam in the second direction with respect to the first direction. Scanning exposure equipment. 7. The scanning exposure apparatus according to claim 2, wherein the intensity distribution detecting means includes a photodetector having a slit-shaped opening that moves along the first direction. 8. The exposure beam is changed by the intensity distribution changing means.
2. The scanning type exposure apparatus according to claim 1, wherein the intensity distribution of the beam in the second direction is changed. 9. A device manufacturing method, comprising the step of transferring a device pattern of a mask onto a substrate to be exposed by using the scanning type exposure apparatus according to any one of claims 1 to 8.