JPH11219893A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity of an aligner by improving the exposure control accuracy of the aligner. SOLUTION: The shielding time of a flux (luminous flux) (p) for lighting light from a light source is reduced to a half, by shielding the flux (p) from an edge side by means of two shutter blades 41a and 41b. In addition, the time required for canceling the shielding of the flux (p) can also be reduced to a half, by having the blades 41a and 41b rotate in the directions in which the blades 41a and 41b separate from each other from a state where the blades 41a and 41b shield the flux (p).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure apparatus used for manufacturing semiconductor elements, liquid crystal display substrates, and the like.

[0002]

2. Description of the Related Art In the manufacture of a semiconductor device or a liquid crystal display device, an exposure apparatus is used to apply an image of a pattern formed on a reticle or a photomask (hereinafter, referred to as a mask) to a semiconductor material coated with a photosensitive agent such as photoresist. Projection exposure is performed on a photosensitive substrate (hereinafter, simply referred to as a substrate) such as a wafer or a glass plate. One of the important factors in such an exposure apparatus is control of the exposure amount. Exposure amount control is performed by opening and closing a shutter provided in the illumination optical system. By performing this exposure amount control with high accuracy, it is possible to improve the yield and contribute to the improvement in productivity. For this reason, various measures have conventionally been taken to speed up the opening and closing of the shutter.

FIG. 8 is a view showing a shutter used in a conventional exposure apparatus. This shutter 4 has a motor 4
The shutter blade 41 is provided with a single shutter blade 41 that is driven to rotate by the rotation of the shutter blade 41.
The opening 44 is opened and closed by 43. For example, opening 4
When the blade 4 is not closed by the blade 42, the illumination light emitted from the light source of the exposure apparatus from the direction of the light passes through the opening 44 and travels in the direction of the light. When the opening 44 is closed, the shutter blade 41 rotates, for example, clockwise,
The blade 43 blocks the opening 44, so that the illumination light from the direction of is reflected by the blade 43 toward the direction.

FIG. 9 is an explanatory diagram showing a time change of the light intensity transmitted through the shutter 4 having such a configuration. As shown in FIG. 9, it takes time a to b from the start of the opening operation of the shutter 4 to the actual start of opening of the shutter 4. For example, as shown in FIG. 10, the distance s1 exists between the edge 42a of the blade 42 of the shutter 4 and the edge p1 of the flux (light flux) p of the illumination light, and the edge 42a of the blade 42 Light flux (luminous flux) p
It takes time to reach the edge p1. Next, at the time point c, the edge 42a of the blade portion 42 completely crosses the flux (light flux) p of the illumination light, and the intensity of the illumination light becomes maximum.

On the other hand, when the shutter 4 performs the closing operation, when the blade portion 43 of the shutter 4 starts the closing operation at the point of time d, the edge 43a of the blade portion 43 has the flux p of the illumination light at the point of time e. Reaches the edge p1 of f
At the point of time, the flux (light flux) p of the illumination light is completely shielded, and at the point of g, the blade portion 43 reaches the shielding complete position.
Here, the total exposure amount (total energy of the flux) due to the opening and closing of the shutter 4 is the area of the trapezoidal portion from time b to time f in FIG. In order to guarantee the total exposure amount, the exposure intensity is monitored by an exposure amount sensor, and the shutter 4 is closed when a predetermined exposure amount is reached.

At this time, if the shutter 4 is closed after detecting the specified exposure amount, an exposure amount between d and f in FIG. 9 is added, resulting in overexposure. This overexposure appears as, for example, a thick or narrow line width of the fine pattern.
Taking into account that the exposure amount in the period f is added, the closing operation of the shutter 4 is started at the time point d when (total exposure amount) − (d to f exposure amount) is sensed. ing.

[0007]

The amount of exposure by the shutter 4 shown in FIG. 9 is a theoretical one. Actually, when the shutter 4 is opened and closed, for example, as shown in FIG.
The diffraction of light by the edges 42a, 43a of the blades 42, 43 shown in FIG. At the time, the edge 42 of the blade portion
Since the speeds of the portions a and 43a are not constant, as shown in FIG. 11, transients occur immediately after the time point b, immediately before the time point c, immediately after the time point e, and immediately before the time point f. B to c and e
Since the time between the time f and the time f is long, an error in the exposure amount due to the opening and closing of the shutter 4 occurs, which hinders an improvement in productivity. The present invention has been made in view of such a problem, and an object of the present invention is to provide an exposure apparatus capable of improving productivity by improving the control accuracy of an exposure amount.

[0008]

In the present invention, the above object is achieved by contracting the opening and closing of the illumination light flux (luminous flux) by two shutter blades in half. That is, the present invention provides an exposure light source, an illumination optical system that irradiates a light beam from the exposure light source to a mask, a projection optical system that transfers an image of the mask onto a substrate, a photodetector that monitors an exposure amount, and an illumination device. A shutter device provided in the optical system;
Control means for controlling opening and closing of the shutter device based on the amount of exposure monitored by the photodetector, wherein the shutter device includes two shutter blades each having a rotation axis.

The pattern on the mask is projected onto the substrate as a substantially equal-sized erect image by a projection optical system fixedly arranged with respect to the illumination optical system. In this case, the amount of exposure applied to the substrate can be controlled by opening and closing the two shutter blades. According to the present invention, 2
By blocking the light beam from the exposure light source from the peripheral direction opposite to the center of the light beam by the shutter blades, the light shielding time can be reduced to half. Also,
By rotating in a direction away from each other from a state in which the light beam is shielded by the two shutter blades, the time required for releasing the light beam from the light can be halved. As a result, an error in the exposure amount due to the two shutter blades can be reduced, so that overexposure and the like can be suppressed. In this case, by rotating the two shutter blades in the same direction, the time required for shielding and releasing the light beam by the two shutter blades can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 7 is a schematic explanatory view of an exposure apparatus according to the present invention. Illumination light emitted from a light source 2 such as an ultra-high pressure mercury lamp disposed in an elliptical mirror 1 is reflected by a reflecting mirror 3 and advances to a shutter 4 for controlling an exposure amount. The exposure controlled by the shutter 4 is detected by an exposure sensor 5. The illumination light having passed through the shutter 4 passes through a lens 6 and a fly's eyes lens 7 for eliminating illuminance unevenness, and reaches a mask blind 8. The mask blind 8 adjusts the illumination range on the mask 12 by the illumination light by changing the size of the opening S.

The illumination light passing through the opening S of the mask blind 8 passes through a condenser lens 9 and is reflected by a reflecting mirror 10.
The light is reflected toward the condenser lens 11. The condenser lens 11 forms an image of the opening S of the mask blind 8 on the mask 12, and illuminates a desired area of the mask 12. An image of a shot pattern or an alignment mark existing in the illumination range of the mask 12 is formed on a substrate 14 coated with a resist by a projection lens 13, thereby exposing the pattern image of the mask 12 to a desired region of the substrate 14. Is done. The substrate 14 is held on an XY stage 15 by vacuum suction. This stage 15
Has a well-known structure in which a pair of blocks movable in directions perpendicular to each other are overlapped.

FIG. 1 is a schematic view showing an example of a shutter relating to an exposure apparatus according to the present invention. The difference between the shutter shown in FIG. 1 and the conventional shutter 4 shown in FIG. 41a and 41b. The shutter 4 includes two shutter blades 41a and 41b.
Thereby, the shielding (shutter closed) and the unblocking (shutter open) of the flux (light flux) p of the illumination light are performed. Also,
The shutter blades 41a and 41b are arranged, for example, point-symmetrically with respect to the illumination light flux, and the rotating shafts 40a and
40b is driven to rotate in the same direction (clockwise in the figure), whereby the shutter blades 41a,
41b is driven to rotate in the same direction.

In FIG. 1, the positions of the motors 40A and 40B are not on the same side with respect to the plane including the shutter blades 41a and 41b, and the respective rotations are considered based on the individual motors 40A and 40B. The direction of rotation of the shaft is reversed. However, when the shutter blades 41a and 41b are viewed from, for example, the motor 40A side, each of the shutter blades is rotating clockwise. Also, the motor 40A,
The direction of rotation by the driving force of the shutter blades 40B may be counterclockwise in both cases.
a, edge 42b, 43b of blade part 42, 43 of 41b
May be driven in such a way as to match near the center of the optical axis.

FIG. 2 is a view showing a state in which the shutter of FIG. 1 is mounted on a support plate.
The drive shafts 40a and 40b of B are rotatably supported by a support plate 45 having an opening 44. Further, the support plate 45 is provided with accommodation grooves 46 for rotatably accommodating the shutter blades 41a and 41b, and the accommodation grooves 46 prevent the shutter blades 41a and 41b from projecting from the support plate 45. It has become so. Of the blades 42, 43 provided in the shutter blades 41a, 41b, for example, the edge 42a of one blade 42 and the edge 43a of the other blade 43 coincide with each other on the opening 44, so that illumination is performed. The light flux p is blocked (shutter closed).

Next, the opening and closing operation of the shutter 4 in the exposure apparatus according to the present invention will be described. First, when the shutter 4 is in the closed state, as shown in FIG. 2B, the edges 42a, 43b of the blade portions 42, 43 of the shutter blades 41a, 41b.
43 a coincide with each other on the opening 44. In this state, when the opening operation of the shutter 4 is started, each motor 40
A, 40B, the shutter blades 41a, 41
1b rotates clockwise. At this time, substantially simultaneously with the start of the opening operation of the shutter 4, the edge 42 of the blade portion 42, 43
As shown in FIG. 3, the flux p of the illuminating light gradually begins to pass from the center portion toward the edge portion p1 through the opening portion 44 in FIG. When the edges 42a and 43a of the blades 42 and 43 completely cross the flux p of the illumination light at the time point c shown in FIG. 3, the intensity of the illumination light becomes maximum.

At this time, the speeds of the edges 42a, 43a of the blades 42, 43 crossing the flux p of the illumination light are:
Since the number of shutter blades is twice as large as that of one shutter blade 41 shown in FIG. 8, the time between ab and c in FIG. 3 is substantially half the time between b and c in FIG. That is, the opening operation for the flux (light flux) p of the illumination light is undertaken in half by the two shutter blades 41a and 41b, whereby the time required to cross the flux p of the illumination light is reduced to half.

Next, when the blades 42, 43 of the shutter 4 start the closing operation at the time point d, the edges 42a, 43a of the blades 42, 43 start to block the flux p of the illumination light, and fg At this point, the flux (light flux) p of the illumination light is completely shielded. The point of this fg is determined by the
7 coincides with the edge 42a of the other blade 42 on the opening 44, and is also the time when the exposure sensor 5 in FIG. At this time, the speeds of the edges 42a and 43a of the blades 42 and 43 that cross the flux p of the illumination light are doubled as compared with the single shutter blade 41 shown in FIG. Therefore, the time between e to fg in FIG. 3 is approximately half of the time from e to f in FIG.

As described above, in this example, the flux (light flux) of the illumination light from the light source 2 is shielded from the edge p1 side by the two shutter blades 41a and 41b, so that the flux (light flux) of the illumination light is obtained. p can be halved, and the two shutter blades 41a,
By rotating in a direction away from each other from the state where the flux (light flux) p of the illumination light is blocked by 41b,
The time required for releasing the shielding of the flux (light flux) p of the illumination light can be halved. As a result, an error in the exposure amount due to the two shutter blades 41a and 41b can be reduced, so that overexposure can be suppressed.

In this example, each shutter blade 41
The case where the shutter blades 41a and 41b are arranged point-symmetrically has been described.
Needless to say, b may be arranged to be line-symmetric. Further, as shown in FIG. 4, a weight 47 may be provided at a position where the blade portions 42 and 43 face each other. By providing the weight 47, the weight balance of each of the blades 42, 43 is maintained, and the rotation of each of the blades 42, 43 is appropriately performed. Therefore, the shutter blades 41a, 41b are used as one blade to form the shutter blades. The total length can be shortened. In this case, it is desirable that the weight 47 be a weight proportional to the weight of each of the blades 42 and 43.

Further, as shown in FIG. 5, the shutter blades 41a and 41b may be arranged side by side. In this case, a driving force from a motor (not shown) is applied to one of the blades 43 via a driving gear 48 and a transmission gear 49 is provided.
By applying the driving force to the other blade portion 42 through the opening and closing, the opening and closing operations of the blade portions 42 and 43 can be performed without crossing each other, and one motor 40A and 40B described above can be used. The configuration can be simplified. Further, as shown in FIG. 6, a driving force from a motor (not shown) is applied to one of the blades 43 via a driving gear 48, and the driving force is applied from the blade 43 to the other blade 42. Alternatively, the configuration may be provided, so that the configuration can be further simplified.

[0021]

According to the present invention, the light from the exposure light source is shielded from the peripheral direction opposite to the center of the light by the two shutter blades, and the light is shielded by the two shutter blades. By rotating them in a direction away from each other, the time required for shielding and releasing the light flux can be halved, and the control accuracy of the exposure amount can be improved.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a state in which the shutter of FIG. 1 is mounted on a support plate.

FIG. 3 is a view showing an exposure amount by a shutter shown in FIG. 1;

FIG. 4 is a schematic view showing another example of the shutter according to the present invention.

FIG. 5 is a schematic view showing another example of the shutter according to the present invention.

FIG. 6 is a schematic view showing another example of the shutter according to the present invention.

FIG. 7 is a schematic view showing an exposure apparatus according to the present invention.

FIG. 8 is an explanatory view of a conventional shutter.

FIG. 9 is a view showing an exposure amount by a conventional shutter.

FIG. 10 is a diagram for explaining the operation of a conventional shutter.

FIG. 11 is a diagram for explaining the operation of a conventional shutter.

[Explanation of symbols]

4 shutter, 40A, 40B motor, 41a, 41
b: shutter blade, 42, 43 ... blade portion, 42b, 43
b ... edge, 44 ... opening, 45 ... support plate, 46
... accommodation groove, 47 ... weight, 48 ... drive gear, 49 ... transmission gear, p ... illumination light flux

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/30 516D

Claims (3)

[Claims] An exposure light source; an illumination optical system for irradiating a light beam from the exposure light source onto a mask; a projection optical system for transferring an image of the mask onto a substrate; a photodetector for monitoring an exposure amount; An exposure apparatus comprising: a shutter device provided in an illumination optical system; and control means for controlling opening and closing of the shutter device based on an exposure amount monitored by the photodetector, wherein each of the shutter devices has a rotation axis. An exposure apparatus comprising two shutter blades. 2. The exposure apparatus according to claim 1, wherein the two shutter blades shield a light beam from the exposure light source from a peripheral direction facing the light beam with the center of the light beam interposed therebetween. 3. The exposure apparatus according to claim 1, wherein the two shutter blades rotate in the same direction.