JPS60257521A - Exposure apparatus for forming pattern - Google Patents

Abstract

PURPOSE:To enable a fine pattern to be formed at a high speed and thereby to permit an improvement in productivity of an integrated circuit, by turning ON a light source when the relative positional relationship between a luminous flux and a substrate to be exposed to light reaches a preset one. CONSTITUTION:A wafer 7 retained on a stage is continuously moved in the direction of X at a rate of 100mm./sec. After chips 9 and 10 have been subjected to light exposure and when the positional relationship between the wafer 7 and a luminous flux 5 reaches one such as that illustrated, an excimer laser is made to emit a laser beam by a trigger from a position detection signal processing unit to sensitize a photoresist film 6. In this arrangement, an excimer laser which is a strong far-ultraviolet light source is employed, and exposure is effected by light in the shape of a pulse for a short period of time while a substrate to be exposed such as a wafer and the luminous flux passing through a mask or reticle are continuously moved relative to each other. It is therefore possible to form a fine pattern at extremely high speed and to greatly improve the productivity of an integrated circuit substrate.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an exposure device for forming a pattern that forms a latent image of a resist pattern on a substrate for an integrated circuit, and particularly relates to an exposure device for forming a pattern using two powerful deep ultraviolet light sources. By using an excimer laser, it is possible to form battens with high precision and high speed.

[Background of the invention]

Among the light sources for exposure in photolithography techniques used in the fabrication of integrated circuits, the most commonly used light source is ultraviolet light. The practical minimum batten size that can be realized by an exposure method using ultraviolet rays is about 1.5 uTn, but as integrated circuits become denser and larger, even finer battens will be required in the future.

One of the factors limiting the minimum batten size in ultraviolet exposure is the wavelength of the ultraviolet light (350 to 450 nm), so in order to obtain even finer battens, shorter wavelengths are desired. Therefore, 200~300n
A method using a wavelength of m has been developed. Deuterium lamps and Hg-Xe lamps are used as light sources, but their intensity is insufficient.

One disadvantage is that it takes several minutes or more for one exposure, and integrated circuits cannot be produced in large quantities and at high speed.

By the way, exposure methods using ultraviolet rays include a contact exposure method, a proximity exposure method, a one-to-one projection exposure method, and a reduction projection exposure method. Among these, the reduction projection exposure method is suitable for producing integrated circuits having two or less tones, but its weak point lies in its processing capacity. For example, when used in the production of integrated circuits called VLSIs, it is possible to achieve a throughput of only about 40 wafers/hour at most with a 4-inch diameter wafer. The biggest reason why processing performance cannot be improved is also called the step-and-repeat method. This method is based on the wafer movement method. In other words, the reticle is fixed, the wafer is accurately stopped at a predetermined position, the shutter is opened and exposed, the shutter is closed, and the wafer is then moved to a predetermined position and the shutter is opened and closed after the reticle is stopped. There is a cause. The time required for each operation varies depending on the usage conditions, but 256, which is said to be a full-scale ultra-LSI,
Assuming the case of a bit random access MOS memory, it is considered that it takes 0.8 to 1 second for movement and rest, and 0.2 seconds for exposure, that is, from opening to closing the shutter,
+. -6, M7, Ka. 'J IPJ* 'it a h
6.3 This is an essential problem with this method, which involves repeating movement and stopping while accurately controlling the position.

It is extremely difficult to speed up this process by an order of magnitude.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned problems in the prior art,
Capable of forming fine patterns at high speed.

Thereby, it is an object of the present invention to provide an exposure apparatus for forming a button, which makes it possible to improve the productivity of integrated circuits.

[Summary of the invention]

The features of the present invention are to achieve the above object.

an optical system that includes at least an excimer laser as a light source, and that forms a beam of light that irradiates the substrate to be exposed after the light from the light source passes through a mask, and a relative positional relationship between the beam of light and the substrate to be exposed; and a control system that causes the light source to emit light when the relative positional relationship reaches a preset positional relationship.

1゛ [Embodiments of the invention] The present invention will be explained in detail with reference to the following eight drawings.

FIG. 1' is a block diagram of a refractive optical system reduction projection type exposure apparatus according to the present invention. 1 is a light source that generates an excimer laser, 2 is an optical system that functions to shape the laser beam and control the exposure amount, 3 is a reticle, 4 is an optical system that converges and images the light beam that has passed through the reticle, and 5 is a laser A luminous flux, 6 a novolak positive photoresist film, 7 a wafer, and 8 a stage for holding and moving the wafer 7. The excimer laser uses KrF gas, has an oscillation wavelength of 249'nm, a pulse output of 700mJ, and a pulse width of 15nsec. The sensitivity of the photoresist film 6 is approximately 50 mJ/cJ. By the optical systems 2 and 4, the laser beam 5 is converged to a 10 mm square on the photoresist film 6, and has sufficient intensity to expose the resist with one pulse.

FIG. 2 is a diagram for explaining in detail the exposure operation in the exposure apparatus of FIG. 1, and 5 is a laser beam.

6 is a photoresist, 7 is a wafer, 9 and 10 are already exposed chips, 11 is a chip being exposed, 12 and 1
3 is the position of the chip to be exposed. The wafer 7 is held on the stage, and in the state shown in FIG.
It is continuously moving at a speed of 0mm/sec. When the chips 9 and 10 are exposed and the positional relationship between the wafer 7 and the light beam 5 becomes as shown in FIG. Expose to light. In this case, the structure is such that the signal processing can be performed while taking into account in advance the time delay between the interior of the 1-position detection signal processing section and the time from receiving the trigger to emitting light. Now, the pulse width of the excimer laser is 15n.
sec, and during this time the wafer 7 supporting the photoresist film 6 is moving at 100 mn/sec. Therefore.

The distance that the wafer moves during the time the pulsed light is emitted is only 0.0015 AM, which is negligible compared to the batten width used in integrated circuits. chip 1
After exposure 1, chips 12 and 13 are sequentially exposed. In the above example, the wafer was continuously moved in the X direction, but by combining movement with the Y direction, it is possible to expose the entire surface of the wafer with a chip pattern. FIG. 3 shows an example of a wafer movement path. When moving as shown in this figure, the time required to expose a 10+nm square chip on the entire surface of a 4-inch diameter wafer is about 6 seconds. Even taking into consideration the time for loading and unloading wafers, the throughput of one exposure device can achieve several hundred wafers/hour.

By the way, according to the above embodiment, the relative moving speed V between the wafer and the reticle is expressed by the following equation.

v (n+n+/5ec) = d (mm) X f
(Hz) Here, d is the repetitive exposure distance pitch, and f is the oscillation frequency of the excimer laser. This is because the maximum oscillation frequency of the excimer laser in this embodiment is 1507.

If d = 10 mn, the maximum value of relative movement speed is v =
It becomes 1500mm/see. Even in this case, 1
The distance the wafer moves in one pulse of 5 nsec is 0.0
It is as small as 225 IMl, and the time required to expose the entire surface of a 4-inch wafer is 0.4 seconds, making it possible to increase throughput by more than 200 times that of the conventional example.

FIG. 4 is an explanatory diagram of the optical systems 2 and 5 in the second embodiment. 14 is a laser beam, 15 is a filter for adjusting laser beam intensity, 16 is a lens for enlarging the laser beam, 17 is a lens for converting the expanded beam into parallel light, 18 is a reticle, and 19 is a wafer for the beam that has passed through the reticle. This is a lens that converges and forms an image on 20 planes. This embodiment illustrates the basic elements of the optical system, and many other modifications can be made using known techniques.

FIG. 5 shows another embodiment. This example illustrates a proximity exposure method. The photoresist film 23 formed on the wafer 24 is exposed by irradiating the light flux 21 that has passed through the mask 22 . The distance between the mask 2z and the photoresist film 23 is several to several tens, and the distance between the laser beam 21 and the wafer 2 is
4 and the photoresist film 23 while continuously changing the relative positional relationship with the photoresist film 23. mask 22
The pattern is transferred onto the photoresist film 23 at the same size.

Same as the previous embodiment.

High-speed exposure can be achieved.

FIG. 6 shows an embodiment of a reduction projection exposure apparatus using a reflective optical system. 28 is an excimer laser and a light source optical system having a function of enlarging and shaping the laser beam and a light amount adjustment function; 29 is a laser beam; 30 is a reticle; 31 is a reflective optical reduction system;
2 is a wafer with a photoresist film formed on its surface, 33
is the reflected and reduced laser beam. The wafer 32 is continuously moving with respect to the laser beam 33, and when the mutual positional relationship reaches a predetermined positional relationship, the excimer laser is emitted in pulses to form a reduced image of the reticle 30 on the surface of the wafer 32. .

FIG. 7 is a diagram illustrating the reflective optical system 31 in FIG. 6. 34 and 35 are reflecting mirrors. Parallel laser beam 2
After passing through the reticle 30, the light beam of the excimer laser shaped into the wafer 3
2 images are formed on the surface.

In the embodiments shown in FIGS. 6 and 7, similar to the embodiments shown in FIGS. 1 to 5, the speed is extremely high compared to the conventional example.

In addition, highly accurate patterns can be formed.

In the above embodiments, a KrF excimer laser was used, but
XeCJ XeF, ArF, F2. An excimer laser such as KrCQ can also be used. Also.

Instead of using an excimer laser alone, a combination of an excimer laser and a Raman shifter can also be used as the light source. Further, a dye laser excited by an excimer laser can also be used as a light source. Furthermore, the photosensitive resin is not limited to the above examples, and widely known materials can be used.

Furthermore, not only wafers but also photomask substrates and the like can be widely used as the substrate to be exposed. In addition, the optical system is not limited to the above-mentioned embodiments, and may be a known lens.

Reflectors, filters, etc. may be used.

In addition, in the two embodiments, the exposed substrate was moved in order to continuously change the relative positional relationship between the exposed substrate and the light beam, but the light beam may also be moved, or the light beam and the exposed substrate may be moved. Both of the exposed substrates may be moved.

〔Effect of the invention〕

As explained above, according to the present invention, an excimer laser, which is a powerful far-ultraviolet light source, is used to continuously move the light flux that has passed through the mask or reticle and the substrate to be exposed, such as a wafer, for a short period of time. Since the exposure is performed using pulsed light, fine patterns can be formed at extremely high speeds, which has the advantage of greatly improving the productivity of integrated circuit boards.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the apparatus according to the embodiment of the present invention, Fig. 2 is an explanatory diagram of the exposure order for explaining its operation, Fig. 3 is an explanatory diagram of wafer movement in Fig. 1, and Fig. 4 is a diagram in Fig. 1. FIG. 5 is a block diagram of another embodiment of the present invention, FIG. 6 is a block diagram of still another embodiment of the present invention, and FIG. 7 is a part of FIG. 6. It is a detailed explanatory diagram. <Explanation of symbols> 1... Excimer laser light source 2.4... Optical system 3, 18. 30... Reticle 5
, 14.21. ．． 29.33...Laser luminous flux 6.2
3... Photoresist film 7, 20. ．． 24.32...Wafer 8...Stage 9-13...Chip 15...Filter 16.17.19...Lens f 22'...
・Mask 34. 35...Reflector 28...Light source optical system 31...Reflective optical reduction system Patent applicant Nippon Telegraph and Telephone Public Corporation il Figure° Comic use 7 t3 Figure 1'4 Figure 1'5 Figure fang 6 Figure 0! Figure 7

Claims (1)

[Scope of Claims] An exposure apparatus used to form a latent image of a resist pattern on a substrate includes at least an excimer laser as a light source, and the light from the light source passes through a mask and then irradiates the substrate to be exposed. an optical system for forming a light beam; and means for continuously changing the relative positional relationship between the light beam and the substrate to be exposed. A control system for causing the light source to emit light when the relative positional relationship reaches a preset positional relationship.