JP3200244B2 - Scanning exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning exposure apparatus, and
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 of semiconductor devices and fine patterns
As the manufacturing process has progressed, slight changes in the manufacturing process have led to a decrease in yield due to an increase in the defective rate.

In particular, in a scanning type exposure apparatus which projects a pattern on a mask onto a wafer by relatively scanning the mask and the wafer with respect to a slit-like light beam, the slit length direction ( Exposure non-uniformity in the direction perpendicular to the scanning direction of the slit-shaped light beam) increases the defect rate when manufacturing a semiconductor device.

[0004]

FIG. 10A shows a state in which a plurality of element patterns are sequentially scanned and exposed in a wafer 14, and the hatched portions in the figure are exposure regions at a certain time. . The element pattern is exposed by repeating scanning and steps in the exposure area as indicated by arrows. In such an exposure method, FIG.
The exposure unevenness within one shot 14a (a range exposed by one scan) shown in FIG. 8C is substantially uniform in the x direction (direction parallel to the scanning direction) as shown in FIG. In the direction (direction perpendicular to the scanning direction), unevenness in the light intensity distribution of the slit-like light beam itself and unevenness in the exposure amount due to the difference in the width of the slit occur.

To correct exposure unevenness on a wafer during scanning exposure, as disclosed in Japanese Patent Application Laid-Open No. Sho 62-193125, the width of a slit is partially changed so that the exposure amount of each portion is changed. There is a way to adjust. FIG. 11 shows an example of a slit having a variable slit width in a scanning exposure apparatus that performs scanning exposure with a ring-shaped light beam. The slit is composed of a number of light shielding members, and the width of the slit is partially changed by adjusting the position by independently moving the many light shielding members. In this method, an extremely large number of movable light-shielding members are required in order to suppress the exposure unevenness, which results in a complicated mechanism.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 61-267722, there is a method of changing the illuminance distribution by moving a plurality of lenses in the illumination optical system in the optical axis direction. FIGS. 12 and 13 show such a plurality of lenses,
The change in the illuminance distribution due to the movement in the optical axis direction is shown. In FIG. 13, the horizontal axis indicates a position (distance from the optical axis) on the irradiated surface, and the vertical axis indicates the illuminance at each position (off-axis) when the illuminance on the optical axis (center) is set to 1. Is shown. FIG.
In the case of the lens position shown in FIG. 2A, the illuminance distribution is as shown in FIG. 13A, and in the case of the lens position shown in FIG. 12B, as shown in FIG. Illuminance distribution. In this example, the illuminance distributions (a) and (b) in FIG. 13 are set as extreme distributions, and the illuminance distribution can be changed continuously within the range of the oblique line in FIG. 13 depending on the lens position.

However, this change in the illuminance distribution changes with a quadratic curve or a curve close to the quadratic curve with respect to the reference as shown in FIGS. When the amount is determined, the correction amount of the illuminance at another image height is also uniquely determined. For example, moving the lens
Even if the illuminance distribution shown in FIG. 5A can be uniformly corrected as shown in FIG. 15B, the illuminance distribution shown in FIG. 15C can be corrected only to about FIG. 15D.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a scanning type exposure apparatus which can correct exposure unevenness accurately.

[0009] scanning exposure apparatus of the present invention, in order to achieve the above object, in a second direction intersecting with said first direction with an exposure beam with a cross sectional shape extending the mask and the exposed substrate in the first direction By scanning, the pattern of the mask is
In the apparatus for projecting on a substrate to be exposed, in the first direction,
An extended aperture defines the cross-sectional shape of the exposure beam.
Has a Mel throttle means, and said mask and intensity distribution changing means for varying the intensity distribution for the first direction in the exposure on the substrate of the exposure beam, said diaphragm means, said dew
Both ends of the cross section of the light beam in the first direction
At least two light-shielding members for defining an edge;
One side of the cross-sectional shape of the beam in the second direction
At least one light-blocking member defining an edge of
The other of the cross-sectional shape of the light beam in the second direction
At least two light-blocking members defining a side edge;
At least two light shielding members with respect to the second direction.
Means for changing the angle .

In a preferred form of the scanning type exposure apparatus according to the present invention, the intensity of the exposure beam in the first direction is provided with a photodetector having a slit-like opening which moves along the first direction. Means for detecting the distribution are provided.

[0011]

In one embodiment of the scanning exposure apparatus according to the present invention, the intensity distribution changing means includes a plurality of lenses movable in an optical axis direction.

In one embodiment of the scanning type exposure apparatus according to the present invention, the intensity distribution changing means comprises a plurality of optical elements having different transmittance characteristics of optical elements coated with different transmittance depending on the incident angle of the light beam, By disposing 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. With multiple lenses.

By using the scanning exposure apparatus of the present invention, semiconductor devices such as ICs and LSIs, imaging devices such as CCDs, display devices such as liquid crystal panels, and various devices such as magnetic heads are accurately manufactured with good yield. It becomes possible.

[0015]

FIG. 1 is a schematic view showing an embodiment of the present invention, in which semiconductor devices such as ICs and LSIs, imaging devices such as CCDs, display devices such as liquid crystal panels, and various devices such as magnetic heads are manufactured. 1 shows a scanning projection exposure apparatus for the present invention. Reference numeral 1 denotes a light source that emits ultraviolet light, such as an ultra-high pressure mercury lamp, and 1a denotes a light emitting unit of the light source 1. Reference numeral 2 denotes an elliptical mirror, and a light emitting unit 1a of the light source 1 is disposed near a first focal point of the elliptical mirror 2, and a light beam emitted from the light emitting unit 1a is condensed at a second focal point 3 of the elliptical mirror 2, and The light emitting unit image 1b is formed at the focal point 3. The light from the light emitting portion image 1b at the second focal point 3 is condensed on the light incident surface of the fly-eye lens 6 as an optical integrator via the condenser lens 4 and the mirror 5, and the light exit surface 6 of the fly-eye lens 6
A plurality of secondary light sources are formed near a. 7 is a reticle 12
A condenser lens (variable illuminance distribution lens) having a function of changing the illuminance distribution described above, and the lens 7 is used to reduce the aperture width of the luminous flux from the plurality of secondary light sources formed on the light exit surface 6a of the fly-eye lens 6. Pointing to a variable slit 9 that can be changed,
The variable slit 9 is Koehler-illuminated. 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 illumination area 90 in the reticle 12 is determined by the size / shape of the opening of the variable slit 9. Reference numeral 13 denotes a projection optical system including a refractive optical system and a catadioptric optical system, and projects the device pattern of the reticle 12 onto the wafer 14. 15 is a wafer chuck,
Reference numeral 16 denotes a wafer stage. The reticle 12 and the wafer 14 are respectively moved in a predetermined scanning direction in synchronization with a corresponding driving device (not shown) at a speed ratio corresponding to the magnification of the projection optical system 13, and at this time, the device pattern of the reticle 12 is moved. Crosses the illumination area 90, the device pattern of the reticle 12 is transferred onto the wafer 14.

Numeral 18 denotes a light quantity detector, which is a half mirror-8.
Receives a part of the exposure light that defines the illumination area 90, and detects the intensity. The exposure unevenness detecting circuit 19 includes a light amount detector 18.
The power input to the lamp 1 is controlled on the basis of the detection result by the above, and the illuminance of the illumination area 90 (entire) of the reticle 12 is maintained at a constant value. Reference numeral 17 denotes a second light amount detector which is mounted on the wafer stage 16 (another stage).
In some cases). The light amount detector 17 moves the wafer stage 16 to
0 (the image of the area 90) is scanned within the illumination area 10
The illuminance distribution within 0 is detected. The exposure unevenness detection circuit 19 detects the exposure unevenness that may occur when exposing the wafer 14 based on the detection result of the light amount detector 17. An output from the uneven exposure detecting circuit 19 causes the uneven exposure correcting circuit 20 to perform an operation of minimizing uneven exposure of the illumination area 100 by the illuminance distribution variable lens 7 and the variable slit 9.

Hereinafter, a method for detecting uneven exposure and a method for correcting uneven exposure in the apparatus shown in FIG. 1 will be described in detail.

The detection of exposure unevenness is performed by using the light amount 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 little influence on the unevenness of the exposure. Therefore, in this case, 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, a light amount detector 17 is used.
5 is limited by a stop longer than the illumination area 10 in the scanning direction, such as the slit 30 in FIG. 5, and the light flux entering the light quantity detector 17 via the stop (or reduced by an ND filter or the like after passing through the stop). (Light beam emitted) is photoelectrically detected, and the detection is repeated by moving the light amount detector 17 with a slit-shaped aperture in a direction orthogonal to the scanning direction, and the illuminance at each position along the orthogonal direction is repeated. Detect the integrated distribution value. Instead of scanning the slit diaphragm in the direction orthogonal to the scanning direction to detect exposure unevenness, the pinhole is scanned in the scanning direction and the direction orthogonal to the scanning direction to scan in the direction orthogonal to the scanning direction (the direction of the slit 9). Irradiation unevenness may be detected by measuring the distribution of integrated values of the illuminance distribution in the scanning direction with respect to the longitudinal direction of the opening).

For correcting uneven exposure, an illuminance distribution variable lens 7 is used.
And a variable slit 9. The variable slit 9 in FIG. 1 has five blades (light shielding plates) 9a to 9 as shown in FIG.
e, and by changing the angle of the edges of the movable blades 9a, 9b with respect to the scanning direction as shown in FIGS. 2A, 2B, and 2C, each of the movable blades 9a, 9b along the direction orthogonal to the scanning direction. The slit width at the position is changed linearly. For example, the angle θ1 with respect to the scanning direction of the blades 9a and 9b
, Θ2 are θ1 = θ2 = 90 as shown in FIG.
In the case of, the exposure distribution in the direction orthogonal to the scanning direction becomes uniform as shown in FIG. 3A, and the angles .theta.1 and .theta.
Θ1 = θ2 <90 as shown in FIG. In the case of (1), the exposure amount distribution in the direction orthogonal to the scanning direction is as shown in FIG. 3B, and the angles .theta.1 and .theta.2 are as shown in FIG. In the case of, the exposure amount distribution in the direction orthogonal to the scanning direction becomes a distribution as shown in FIG. By changing the angle of the edges of the blades 9a and 9b of the variable slit 9 with respect to the scanning direction, the exposure distribution in the direction orthogonal to the scanning direction is changed as shown in FIG. The illuminance distribution variable lens 7 is disclosed in, for example,
No. 2 discloses a lens system as shown in FIG.
Changing the illuminance distribution of the illumination areas 90 and 100
Therefore, the exposure amount distribution in the direction orthogonal to the scanning direction can be changed.

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

The use of the two exposure unevenness correcting means makes it possible to minimize exposure unevenness in a direction orthogonal to the scanning direction. The amount of movement of the movable lens of the variable illuminance distribution lens 7 in the optical axis direction and the inclination angle of the movable blade of the variable slit 9 when performing this correction are uniquely determined in advance by calculation in accordance with exposure unevenness. You can stay,
The exposure amount distribution may be optimized by repeating detection and correction of exposure unevenness using the light amount detector 17 and the like, the illuminance distribution variable lens 7 and the variable slit 9.

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

In the above embodiment, the angles θ ₁ and θ ₂ of the blades 9 a and 9 b of the variable slit 9 are defined as θ ₁ = θ ₂
However, it is not always necessary. For example, when there is a non-uniform exposure unevenness in a direction orthogonal to the scanning direction of the wafer 14, θ ₁ θθ ₂ may be set.
The movable blades of the variable slit 9 are not limited to two blades 9a and 9b as shown in FIG. 2, but three or four movable blades are supplied. The angles may be set independently of each other.

In the above embodiment, an ultra-high pressure mercury lamp is used as a light source.
Lasers such as lasers 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 (a semiconductor chip such as an IC or an LSI, a liquid crystal panel or a CCD). In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2
In (Mask production), a mask (reticle 304) on which the designed circuit pattern is formed is produced. 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 lithography using the prepared mask and wafer. 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) And the like. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (Step 7)
Is done.

FIG. 9 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the surface of the wafer (wafer 306). Step 12 (CV
In D), an insulating film is formed on the surface of the wafer. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. Step 14 (ion implantation) implants ions into the wafer. Step 15 (resist processing)
Then, a resist (sensitive material) is applied to the wafer. Step 16 (exposure) uses the projection exposure apparatus to expose the wafer using the image of the circuit pattern on the mask (reticle 304). Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist are removed. In step 19 (resist stripping), unnecessary resist 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 is 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 the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration and a function of a variable slit in FIG. 1;

FIG. 3 is a diagram showing a state of a change in an exposure amount distribution by a variable slit in FIG. 1;

FIG. 4 is an explanatory diagram showing a state in which exposure unevenness is corrected using the illuminance distribution variable 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 a means for correcting exposure unevenness.

FIG. 7 is a diagram showing a state of a change in an exposure amount distribution by the correction unit in FIG. 6;

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

FIG. 9 is a view showing a wafer process of FIG. 8;

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

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

FIG. 12 is a diagram illustrating 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 illustrating a change in illuminance distribution by the illuminance distribution variable lens.

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mercury lamp 2 elliptical mirror 4 condenser lens 6 fly-eye lens 7 variable illumination distribution lens 9 variable slit 9 a, 9 b movable blade 10 imaging lens 12 reticle 13 projection optical system 14 wafer 15 wafer chuck 16 wafer stay Reference signs 17, 18 Light intensity detector 19 Exposure unevenness detection circuit 20 Exposure unevenness correction circuit 30a, 30b Illuminance distribution variable element

Claims (7)

(57) [Claims] The method according to claim 1] pattern of the mask by at exposure beam by scanning in a second direction intersecting with said first direction having a cross-sectional shape of the mask and the exposed substrate extending in a first direction
In a scanning exposure apparatus that projects onto the substrate to be exposed,
Before the exposure beam by an opening extending in the first direction
Serial and stop means for defining the cross-sectional shape, the exposure bi - and an allowed to change the mask and the intensity distribution for the first direction in the exposure on the substrate of beam intensity distribution changing means, the throttle
The means comprises a first direction of the cross-sectional shape of the exposure beam.
At least two light-shielding portions defining edges at both ends with respect to
Material, in the second direction of the cross-sectional shape of the exposure beam
At least one shade defining one side edge
Member and the second direction of the cross-sectional shape of the exposure beam
At least two screens defining the other side edge with respect to
A light member, and the second member of each of the at least two light shielding members.
Means for changing angles with respect to two directions . 2. A claims, characterized in that it comprises means for detecting the intensity distribution for the first direction of said exposure beam
Item 2. A scanning exposure apparatus according to Item 1 . Wherein the intensity distribution changing unit, claims, characterized in that it comprises a plurality of lenses movable in an optical axis direction
The scanning exposure apparatus according to claim 1 or 2 . 4. The intensity distribution changing means comprises a plurality of optical elements having different transmittance characteristics of optical elements coated with different transmittances depending on the incident angle of light rays, and a desired one of the plurality of optical elements. The scanning exposure apparatus according to claim 1, wherein an intensity distribution of the exposure beam is changed by disposing an optical element near a pupil plane of the system. 5. The apparatus according to claim 1, wherein said intensity distribution detecting means is provided in said first direction.
Photodetector with slit-shaped opening
The scanning exposure apparatus according to claim 2, wherein
Place. 6. The exposure beam changing means according to claim 1 , wherein
Changing the intensity distribution of the system in the second direction.
The scanning exposure apparatus according to claim 1, wherein: 7. The method according to claim 1, wherein:
Mask devices putter with a scanning exposure equipment according
Transferring the pattern onto the substrate to be exposed.
Device manufacturing method.