JPH1092727A - Projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize setting or selection of optimum exposure performance, corresponding to a product to be manufactured by making an illumination optical system have illumination region varying means for varying the width of an illumination region in a first direction, with respect to an illumination region on a mask. SOLUTION: To change the illumination width (slit width), a slit plate 61 on which a plurality of slits, having different widths are formed, provided on a turret. The slit plate 61 is rotated within a plane perpendicular to the illumination optical axis by a driving section 39. On the slit plate 61, a plurality of slits 62a to 62d having different widths are formed. When the widths of the slits are changed, the exposure performance changes. Thus, a semiconductor device of a high integration degree may be manufactured at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure apparatus used to manufacture a semiconductor device by exposing a design pattern on a resist on a substrate.

[0002]

2. Description of the Related Art In a one-shot exposure type exposure apparatus, when a projection optical system is constituted by a lens, an image forming area has a circular shape. However, since the semiconductor integrated circuit generally has a rectangular shape, the transfer area in the case of batch exposure is a rectangular area inscribed in a circular imaging area of the projection optical system. Therefore, even the largest transfer area has a diameter of 1 /
正方形 2 is a square with sides. On the other hand, the transfer area is enlarged by scanning and moving the reticle and wafer synchronously using a slit-shaped exposure area having a diameter approximately equal to that of the circular imaging area of the projection optical system. A scanning exposure method (step and scan method) has been proposed. In this method, when a projection optical system having an imaging area of the same size is used, a larger transfer area is secured as compared with the step-and-repeat method in which collective exposure is performed for each transfer area using a projection lens. be able to. That is, since there is no restriction by the optical system in the scanning direction, it is possible to secure only the stroke of the scanning stage, and it is possible to secure approximately √2 times the transfer area in the direction perpendicular to the scanning direction. .

An exposure apparatus for manufacturing a semiconductor integrated circuit is required to have an enlarged transfer area and an improved resolution in order to cope with the manufacture of a chip having a high degree of integration. The fact that a smaller projection optical system can be employed is advantageous from the viewpoint of optical performance and cost, and the exposure method of the step-and-scan method is attracting attention as a mainstream of future exposure apparatuses.

[0004]

SUMMARY OF THE INVENTION The inventors of the present invention have made various studies to improve the exposure performance of such a step-and-scan type exposure apparatus (scanning exposure apparatus). ) Has an effect on the exposure performance. However, for example, if the slit width is increased, the distortion is improved but the throughput is reduced. The invention has been reached.

That is, an object of the present invention is to provide an exposure apparatus capable of setting or selecting an optimum exposure performance according to a product to be manufactured.

[0006]

In order to achieve the above object, the present invention provides a light source for generating illumination light, an illumination optical system for illuminating a predetermined area with a light beam from the light source, and a pattern on a mask. A projection optical system for projecting onto the substrate, and scanning means for scanning the mask and the photosensitive substrate in a first direction in synchronization with each other, and sequentially forming a pattern image on the mask on the photosensitive substrate. In the apparatus, the illumination optical system may include an illumination area varying unit that varies a width of the illumination area in the first direction with respect to the illumination area on the mask.

[0007] In a preferred embodiment of the present invention, the illumination area variable means is provided in a position substantially optically conjugate with the mask in the vicinity of the mask surface or in the illumination optical system, or in a direction of the optical axis from the conjugate position thereof. The position of the light-shielding plate disposed at a position separated by a predetermined distance in the first direction is adjusted. Alternatively, the illumination area changing means selects one of a plurality of diaphragms having different widths in the first direction and optically substantially corresponds to the mask in the vicinity of the mask surface or in the illumination optical system. It is characterized by being arranged at a conjugate position or at a position separated from the conjugate position by a predetermined distance in the optical axis direction. In this case, the plurality of apertures are, for example, rectangular slits formed concentrically with the light-shielding plate in a disk-shaped light-shielding plate, and the illumination area changing unit adjusts the aperture selected by rotating the light-shielding plate. It is characterized by being arranged at a conjugate position or at a position separated by a predetermined distance from the conjugate position.

[0008]

According to the present invention, in the scanning type projection exposure apparatus, the width of the illumination area in the scanning direction can be changed according to the purpose, so that the optimum exposure characteristic as the projection apparatus according to the product is obtained. Can be set or selected. For example, the illumination area is narrowed when the priority is given to the throughput, and is expanded when the priority is given to the accuracy.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a state of an exposure apparatus according to an embodiment of the present invention viewed from a side.
FIG. 2 is a perspective view showing the appearance of the exposure apparatus. As shown in these figures, this exposure apparatus projects a part of the pattern of an original on a reticle stage 1 onto a wafer on a wafer stage 3 via a projection optical system 2, and The pattern of the reticle is exposed on the wafer by synchronously scanning the reticle and the wafer in the Y direction. This is a step-and-scan type exposure apparatus.

The reticle stage 1 is driven by a linear motor 4 in the Y direction,
a is driven in the X direction by the linear motor 5, and the Y stage 3 b is driven in the Y direction by the linear motor 6. The synchronous scanning of the reticle and the wafer is performed by driving the reticle stage 1 and the Y stage 3b at a constant speed ratio in the Y direction (for example, 4: -1, where "-" indicates that the directions are opposite). Do. The step movement in the X direction is performed by the X stage 3a.

The wafer stage 3 is provided on a stage base 7, and the stage base 7 is connected to three stages through three dampers 8.
It is supported on a floor at a point. The reticle stage 1 and the projection optical system 2 are provided on a barrel base 9, and the barrel base 9 is supported on a base frame 10 mounted on a floor or the like via three dampers 11 and columns 12. I have. The damper 8 is an active damper for actively damping or removing vibrations in six axial directions. However, a passive damper may be used, or the damper 8 may be supported without a damper.

The exposure apparatus includes a distance measuring means 13 such as a laser interferometer and a micro encoder for measuring the distance between the lens barrel base 9 and the stage base 7 at three points.

The light projecting means 21 and the light receiving means 22 constitute a focus sensor for detecting whether or not the wafer on the wafer stage 3 is located on the focus surface of the projection optical system 2. That is, the wafer is irradiated with light from an oblique direction by the light projecting means 21 fixed to the lens barrel base 9, and the position of the reflected light is detected by the light receiving means 22, whereby the direction of the optical axis of the projection optical system 2 is adjusted. Of the wafer surface is detected.

In this configuration, when the wafer is loaded onto the wafer stage 3 through the transport path between the two columns 12 at the front of the apparatus by the transport means (not shown), and the predetermined alignment is completed, the exposure apparatus While repeating the scanning exposure and the step movement, the reticle pattern is exposed and transferred to a plurality of exposure regions on the wafer. At the time of scanning exposure, the reticle stage 1 and the Y stage 3b are moved at a predetermined speed ratio in the Y direction (scanning direction) to scan a pattern on the reticle with slit-like exposure light, and to project a wafer with the projected image. To expose a pattern on the reticle to a predetermined exposure area on the wafer. During the scanning exposure, the height of the wafer surface is measured by the focus sensor, and the height and tilt of the wafer stage 3 are controlled in real time based on the measured values, and focus correction is performed. When the scanning exposure for one exposure region is completed, the X stage 3a is driven in the X direction to move the wafer stepwise, thereby positioning the other exposure region with respect to the start position of the scanning exposure and performing the scanning exposure. The combination of the step movement in the X direction and the movement for scanning exposure in the Y direction allows each of the exposure areas to be sequentially and efficiently exposed to a plurality of exposure areas on the wafer. , The scanning direction of either positive or negative Y, the order of exposure to each exposure area, and the like are set.

In the apparatus shown in FIG. 1, light emitted from a laser interferometer light source (not shown) is introduced into a reticle stage Y-direction laser interferometer 24. The light introduced into the Y-direction laser interferometer 24 is transmitted to the laser interferometer 24 by a beam splitter (not shown) in the laser interferometer 24.
The light is divided into light directed toward a fixed mirror (not shown) and light directed toward the Y-direction movable mirror 26. The light traveling to the Y-direction moving mirror 26 passes through the Y-direction length measuring optical path 25 and enters the Y-direction moving mirror 26 fixed to the reticle stage 4. The light reflected here returns to the beam splitter in the laser interferometer 2 through the Y-direction length measuring optical path 25 again, and is superimposed on the light reflected by the fixed mirror. The movement distance in the Y direction is measured by detecting a change in light interference at this time. The movement distance information measured in this way is fed back to a scanning controller (not shown), and positioning control of the scanning position of the reticle stage 4 is performed. Similarly, the Y stage 3b controls the scanning position based on the length measurement result by the wafer stage Y direction laser interferometer 23.

FIG. 3 shows an example of the configuration of the illumination optical system in the apparatus shown in FIG. In FIG. 1, reference numeral 31 denotes a fly-eye lens, which is composed of a group of a plurality of minute lenses, receives a light beam from an unillustrated illumination light source such as an excimer laser or the like, and emits a plurality of secondary light sources near a light exit surface. Form. 32 is a condensing optical system for condensing the light beam from the fly-eye lens 31,
33a and 33b are movable slits for determining the width of illumination, and 3
Reference numeral 5 denotes an imaging lens that projects the light-collecting surface 34 onto the reticle R via the mirror 36. The reticle R is scanned in the scanning direction indicated by the arrow a. The light-collecting surface 34 has an optically conjugate positional relationship with the reticle R, and the movable slits 33a and 33b are located at a position separated from the light-collecting surface 34 by a predetermined distance Δd in the optical axis direction. Thus, the movable slits 33a, 33b
Of the movable slit 33 by shifting
The light amount distribution in the scanning direction of the illumination area on the reticle R determined by a and 33b is a trapezoidal distribution as shown in FIG. Reference numeral 39 denotes a drive system for changing the slit width, which drives the movable slits 33a and 33b in a direction indicated by an arrow b perpendicular to the scanning direction and the direction of the illumination optical axis, thereby obtaining the slit width (scanning of the illumination area on the reticle R). The width in the direction is narrowed or expanded, and the light amount distribution is changed to a solid line 41 or a broken line 42 in FIG.
Can be changed as shown in FIG.

The above Δd can be set to 0 or −. That is, the movable slits 33a and 33b can be placed on the light-collecting surface 34,
It is also possible to place it on the side close to 5. However, when the movable slits 33a and 33b are placed on the light-collecting surface 34, the light amount distribution in the scanning direction becomes rectangular.

FIG. 5 shows another example of the configuration of the illumination optical system in the apparatus shown in FIG. The movable slits 33a and 33b are arranged near the reticle R.

FIG. 6 shows another example of the configuration of the illumination optical system in the apparatus shown in FIG. In order to change the illumination width (slit width), a slit plate 61 in which a plurality of slits having different widths are formed is arranged on a turret (not shown), and the driving unit 39 moves the slit plate 61 to a plane perpendicular to the illumination optical axis. Is rotated as shown by the arrow c. As shown in FIG. 7, a plurality of slits 62a to 62d having different widths w are formed in the slit plate 61.

In the scanning exposure apparatus of FIG. 1, when the width of the slit is changed, the exposure characteristics change. For example, as the slit width increases, the throughput decreases because the scanning distance between the reticle stage and the wafer stage must be extended accordingly.

Table 1 shows the relationship between the slit width and each exposure characteristic studied by the present inventors.

[0022]

[Table 1]

Therefore, by appropriately setting the slit width with reference to Table 1, it is possible to select or set an optimum exposure characteristic within a range permitted by the exposure apparatus and perform exposure. For example, when giving priority to throughput and running cost, the slit width may be reduced, and when giving priority to accuracy, the slit width may be increased.

[0024] Example of manufacture of microdevices Figure 8 is a microdevice (IC or LSI, etc. of the semiconductor chip,
2 shows a flow of manufacturing a liquid crystal panel, a CCD, a thin-film magnetic head, a micromachine, and the like. In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4
The (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) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. Step 6
In (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 9 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are 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 conventionally difficult to manufacture, at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a side view of a scanning exposure apparatus to which the present invention is applied;

FIG. 2 is a perspective view showing an appearance of the exposure apparatus of FIG.

FIG. 3 is a diagram illustrating an example of a configuration of an illumination optical system in FIG. 1;

FIG. 4 is a graph showing a light amount distribution of an illumination area on a reticle in a scanning direction in FIG. 3;

FIG. 5 is a diagram illustrating another configuration example of the illumination optical system in FIG. 1;

FIG. 6 is a diagram showing still another configuration example of the illumination optical system in FIG. 1;

FIG. 7 is a plan view of the slit plate in FIG. 6;

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

FIG. 9 is a diagram showing a detailed flow of a wafer process in FIG. 8;

[Explanation of symbols]

1: reticle stage, 2: projection optical system, 3: wafer stage, 3a: X stage, 3b: Y stage, 3c:
Flat stage, 3d: wafer chuck, 4, 5,
6: linear motor, 7: stage base, 8: damper,
9: lens barrel surface plate, 10: base frame, 11: damper,
12: prop, 13: distance measuring means, 18, 19: center of gravity,
20: cross section of exposure light, 21: light projecting means, 22: light receiving means, 23, 24: laser interferometer, 25: laser measuring optical path, 26, 27: moving mirror, 31: fly-eye lens, 3
2: condensing optical system, 33a, 33b: movable slit, 3
4: condensing surface, 35: imaging lens, 36: mirror, 39:
Movable slit drive systems 41, 42: light quantity distribution, 61: slit plates 61, 62a to 62d: slit.

Claims (5)

[Claims] 1. A light source for generating illumination light, an illumination optical system for illuminating a predetermined area with a light beam from the light source, a projection optical system for projecting a pattern on a mask onto a photosensitive substrate, the mask and the photosensitive substrate A projection exposure apparatus that has a scanning unit that scans in a first direction in synchronization with each other, and sequentially forms a pattern image on the mask on the photosensitive substrate. ,
A projection exposure apparatus, comprising: an illumination area varying unit that varies a width of the illumination area in the first direction. 2. The illumination area variable means is located in the vicinity of the mask surface or in a position optically substantially conjugate with the mask in the illumination optical system or at a position separated from the conjugate position by a predetermined distance in the optical axis direction. 2. The projection exposure apparatus according to claim 1, wherein a position of the light-shielding plate disposed in the first direction is adjusted. 3. The illumination area changing means selects one of a plurality of diaphragms having different widths in the first direction and optically connects the mask in the vicinity of the mask surface or in the illumination optical system. 2. The projection exposure apparatus according to claim 1, wherein the projection exposure apparatus is disposed at a substantially conjugate position or at a position separated from the conjugate position by a predetermined distance in the optical axis direction. 4. The plurality of stops are rectangular slits formed concentrically with the light-shielding plate in a disk-shaped light-shielding plate, and the illumination area changing means is configured to turn the light-shielding plate to select the selected stop. Is disposed at the conjugate position or at a position separated by a predetermined distance from the conjugate position.
The projection exposure apparatus according to claim 1. 5. A semiconductor device manufactured using the projection exposure apparatus according to claim 1.