JP3327284B2 - 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 an exposure apparatus, and more particularly, to an exposure apparatus having a light source for emitting light in an ultraviolet region.

[0002]

2. Description of the Related Art In a lithography process for manufacturing a semiconductor element or a liquid crystal substrate, an exposure apparatus for exposing a pattern image of a mask such as a reticle (photomask or the like) onto a photosensitive substrate via a projection optical system is used. Have been. In recent years, semiconductor integrated circuits have been developed in the direction of miniaturization, and in the lithography process, a method of shortening the exposure wavelength of a lithography light source has been considered as a means for further miniaturization.

At present, an exposure apparatus employing a KrF excimer laser having a wavelength of 248 nm as a stepper light source has already been developed. Also, a harmonic of a wavelength variable laser such as a Ti-sapphire laser, a fourth harmonic of a YAG laser having a wavelength of 266 nm, a fifth harmonic of a YAG laser having a wavelength of 213 nm, a mercury lamp having a wavelength of around 220 nm or 184 nm, and an ArF having a wavelength of 193 nm Excimer lasers and the like have attracted attention as candidates for short-wavelength light sources.

In a conventional exposure apparatus using a g-line, an i-line, a KrF excimer laser or a mercury lamp which emits light having a wavelength of about 250 nm as a light source, the emission spectrum lines of these light sources show oxygen absorption as shown in FIG. It did not overlap with the spectral region, and there was no inconvenience due to a decrease in light use efficiency due to oxygen absorption and ozone generation due to oxygen absorption. Therefore, these exposure apparatuses were basically able to perform exposure in an air atmosphere.

However, as shown in the figure, in a light source such as an ArF excimer laser, the emission spectrum line overlaps with the oxygen absorption spectrum region. Inconvenience due to the occurrence occurs. For example, if the transmittance of ArF excimer laser light in a vacuum or in an inert gas such as nitrogen or helium is 100% / m, the free-run state (natural emission state), that is, about 90% in an ArF broadband laser. / M, the transmittance is reduced to about 98% / m even when an ArF narrow band laser having a narrowed spectrum width and avoiding the oxygen absorption line as shown is used.

[0006] The decrease in transmittance is considered to be due to the absorption of light by oxygen and the effect of the generated ozone. The generation of ozone not only adversely affects the transmittance (light utilization efficiency), but also degrades the performance of the device due to the reaction with the optical material surface and other components and causes environmental pollution.

As described above, in an exposure apparatus having a light source such as an ArF excimer laser, it is necessary to fill the entire optical path with an inert gas such as nitrogen in order to avoid a decrease in light transmittance and generation of ozone. Is well known. In general, an exposure apparatus includes an illumination optical system for uniformly illuminating a reticle with light from a light source, a projection optical system for forming a circuit pattern formed on the reticle on a wafer, and supporting and moving the wafer appropriately. And stage means for positioning.

[0008]

In the exposure apparatus having the above structure, the illumination optical system, the reticle, and the projection optical system are hermetically enclosed by containers, and the air in each container is inert gas such as nitrogen gas. Exposure projection.
Since the illumination optical system and the projection optical system are basically composed of units that are not driven, once the inert gas atmosphere is formed, the inert gas atmosphere is not broken during a predetermined exposure and projection process. However, in the reticle portion, the inert gas atmosphere is broken each time the reticle is replaced, so it takes time to re-evacuate and fill the inert gas to form a desired inert gas atmosphere, and the throughput is significantly reduced. There was an inconvenience. Further, when a plurality of reticles are used for one wafer, there is a disadvantage that the reticle replacement frequency is further increased and the throughput is further reduced.

Further, around the reticle table on which the reticle is mounted, many members related to alignment of the reticle, such as an alignment sensor, are arranged, and the fluctuation due to the gas flow accompanying the re-introduction of the inert gas is caused by the atmosphere. , And may cause an alignment error. For this reason, after re-introducing the inert gas, the alignment of the reticle must be waited until the atmosphere is settled, and there is a disadvantage that it takes more time to re-create a desired inert gas atmosphere.

The present invention has been made in view of the above problems, and has as its object to provide an exposure apparatus capable of performing exposure in a required inert gas atmosphere and having improved throughput.

[0011]

According to the present invention, there is provided an illumination optical system (IL) for illuminating a first mask (R1) having a pattern formed by light from a light source (EXL). ) And a projection optical system (PL) for transferring an image of the pattern onto a substrate, wherein an inert member is provided between the optical member on the substrate side of the projection optical system (PL) and the substrate (W). Atmosphere forming means for forming a gas atmosphere, a first container surrounding the illumination optical system (IL), a second container surrounding the projection optical system (PL), and the first mask (R1) The first room (1) surrounding the
The first container, the second container, and the first chamber (1), respectively, so that the first container and the second chamber have a desired inert gas atmosphere. An exposure apparatus having a container and gas supply means for supplying an inert gas to each of the first chambers (1) is provided.

According to a preferred embodiment of the present invention, the gas supply means has a second chamber for holding a second mask, which is to be replaced with the first mask, before transporting the second mask to the first chamber. Preferably, the inert gas is supplied to the second chamber. And it is desirable that each of the first container, the second container, the first chamber, and the second chamber communicates with an exhaust system. Further, the gas supply means includes the first container, the second container, and the first container.
It is desirable to supply an inert gas to each of the chamber and the second chamber via a valve. Further, it is preferable that the atmosphere forming means has a container surrounding a stage for holding the substrate. Further, it is preferable that the apparatus further includes an ionization unit that ionizes the inert gas supplied to the second chamber.

[0013]

According to the present invention, there is provided an exposure apparatus comprising: an illumination optical system for illuminating a first mask on which a pattern is formed with light from a light source; and a projection optical system for transferring an image of the pattern onto a substrate. Atmosphere forming means for forming an inert gas atmosphere between the optical member on the substrate side of the projection optical system and the substrate, a first container surrounding the illumination optical system, and a second container surrounding the projection optical system Container, and the first
A first chamber surrounding the mask, the first container, the second container, and the first chamber, respectively, in order to individually bring the first chamber into a desired inert gas atmosphere. , A gas supply means for supplying an inert gas to each of the second container and the first chamber.

As described above, in the exposure apparatus of the present invention, a plurality of independent spaces including the space surrounding the mask can be formed between the light source and the substrate, and a desired inert gas is provided for each space. An atmosphere can be formed.

For example, even if the space for accommodating the reticle is opened to the atmosphere when the reticle is replaced, the inert gas atmosphere in the other space will not be broken. Also, even if the inert gas atmosphere in the space containing the reticle is broken,
The desired inert gas atmosphere can be reformed independently of the other spaces.

Further, by supplying an ionized gas as an inert gas, static electricity of the reticle can be removed, and furthermore, the reticle can be prevented from being charged even during standby.

[0017]

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically illustrating a configuration of an exposure apparatus according to an embodiment of the present invention. The illustrated device is, for example, A
A light source EXL that emits short-wavelength laser light such as an rF excimer laser is provided. The light beam emitted from the light source EXL is reflected by a plurality of appropriately arranged mirrors and uniformly illuminates the reticle R via an appropriate illumination optical member. Light source E
An optical path from XL to the reticle R constitutes an illumination optical system IL. The illumination optical system IL is surrounded by a container, and the container is supplied with an inert gas such as a nitrogen gas via a valve V5.

The light transmitted through the reticle R is reflected by the projection optical system P
L reaches the surface of the wafer W mounted on a wafer stage (not shown) via various optical members constituting L,
The pattern on the reticle R is imaged. The projection optical system PL is also surrounded by a container, which is supplied with nitrogen gas via a valve V1. Furthermore, the reticle is also surrounded by a container, which is supplied with nitrogen gas via a valve V3.

The container surrounding the illumination optical system IL communicates with the exhaust duct via the valve V6, the oxygen sensor S, and the rotary pump RP. On the other hand, the projection optical system P
The container surrounding L is connected to the exhaust duct via the valve V2, the oxygen sensor S, and the rotary pump RP. The container surrounding the reticle communicates with the exhaust duct via the valve V4, the oxygen sensor S, and the rotary pump RP.

The final optical member of the projection optical system PL and the wafer W
A desired inert gas atmosphere is formed between these steps by an appropriate method. Specifically, the whole stage device on which the wafer W is mounted is surrounded by a container from the lower end of the projection optical system PL, and the container is filled with an inert gas. There is a method of forming an inert gas atmosphere by continuously supplying an inert gas to an open space therebetween.

FIG. 2 is a diagram schematically showing a configuration of a reticle portion of the exposure apparatus of FIG. As shown in FIG. 2, the apparatus of FIG. 1 has a first chamber 1 for hermetically surrounding a first reticle R1 to be projected and exposed. In the first room 1,
Reticle R1 is positioned on reticle table RT by the action of alignment section A. The illustrated device comprises a second chamber 2 adjacent to the first chamber 1. The first chamber 1 and the second chamber 2 are partitioned by a mechanical shutter S1 that can be freely opened and closed. Two arms 5, 6 of the reticle transport mechanism M are provided in the second chamber 2, and the first arm 5 holds the reticle R2 to be projected and exposed next without holding the first arm 5 at all. And waiting.

As described above, the first chamber 1 is connected to the exhaust system and the gas supply system via the valve, while the second chamber 2 is provided with the ionized nitrogen through the valve V7 and the ionized gas generator 4. Gas is supplied.
In the ionized gas generator 4, for example, nitrogen gas is ionized by a two-photon absorption effect by ultraviolet light irradiation. The second chamber 2 communicates with an exhaust duct via a valve V8, an oxygen sensor S, and a rotary pump.

Further, the third chamber 3 is adjacent to the second chamber 2 via the second shutter S2. In the third chamber 3, a reticle cassette (reticle library) RC for accommodating a plurality of reticles is provided. In the reticle cassette RC, reticles R3 to RN to be sequentially projected and exposed are provided.
Is housed.

In the exposure apparatus according to the embodiment of the present invention configured as described above, the first chamber 1
And the second chamber 2 is in the atmosphere, and the shutters S1 and S2 are open. Next, the first and second arms 5 and 6 of the transport mechanism M are actuated, and the reticles R1 and R2 from the reticle cassette RC in the third chamber 3 respectively.
And take it out. The first arm 5 holding the reticle R1 passes through the second chamber 2, places the reticle R1 on the reticle table RT in the first chamber 1, and returns to the second chamber 2. On the other hand, the second arm 6 holding the reticle R2
When returning to the second chamber 2, the apparatus enters a standby state without going to the first chamber 1.

When the first and second arms 5 and 6 respectively hold the reticles R1 and R2 and leave the third chamber 3, the shutter S2 is closed and the reticle R is inserted into the first chamber 1.
When 1 is conveyed and the first arm 5 leaves the first chamber 1, the shutter S1 is closed. When the shutters S1 and S2 are closed, the first chamber 1 and the second chamber 2 are individually evacuated, and the first chamber 1 is filled with nitrogen gas.
Is filled with an appropriately ionized nitrogen gas. The filling pressure is equal to or higher than the atmospheric pressure.

When the first chamber 1 is filled with a nitrogen gas to form a desired inert gas atmosphere, the alignment unit A is operated to position the reticle R1 on the reticle table RT. After the positioning of the reticle R1, a predetermined projection exposure is performed. That is, the circuit pattern formed on the reticle R1 is transferred to each exposure area of the wafer W.

When the projection exposure of the reticle R1 is completed, the shutter S1 is opened and the transport mechanism M is operated to exchange the exposed reticle R1 with the next reticle R2 to be exposed. Specifically, the first arm 5 is introduced into the first chamber 1 to hold the exposed reticle R1, and is carried into the second chamber 2, and the second arm 5 that holds the reticle R2 to be exposed next.
Is introduced into the first chamber, and the reticle R2 is placed on the reticle table RT. When the reticle R2 is placed on the reticle table RT and the second arm 6 leaves the first chamber 1 and returns to the second chamber 2, the shutter S1 is closed.

While the shutter S1 is opened and then closed again, the ionized nitrogen in the second chamber 2 flows into the first chamber 1, but the inert gas atmosphere in the first chamber 1 is substantially reduced. It is not broken, and almost no flow of the atmosphere occurs. Therefore, immediately after the shutter S1 is closed, the positioning of the reticle R2 can be immediately performed, and a predetermined projection exposure can be started.

On the other hand, the shutter S2 is opened immediately after the shutter S1 is closed, the first arm 5 holding the exposed reticle R1 is introduced into the third chamber 3, and the reticle R1 is moved to a predetermined position in the reticle cassette RC. Return to the position,
The second arm 6 is introduced into the third chamber 3 to hold the reticle R3 to be waited in the second chamber 2 for the next exposure, and
It is transported into the chamber 2.

When the first arm 5 and the second arm 6 holding the reticle R3 return into the second chamber 2, the shutter S2 is closed. When the shutter S2 is closed, the second chamber 2 is evacuated and filled with an appropriately ionized nitrogen gas at a pressure higher than the atmospheric pressure to recreate a desired inert gas atmosphere. Reforming of the inert gas atmosphere in the second chamber 2 is performed during the projection exposure of the reticle R2.

By repeating the above steps, projection exposure can be performed by sequentially changing the reticle without substantially breaking the inert gas atmosphere in the first chamber 1.

In this embodiment, the second chamber 2 and the first chamber 1
An ionized active gas atmosphere is formed inside (gradually after the first reticle exchange). The reticle cassette RC and the reticle R are easily charged in the cleaning step and the transport step, and the circuit pattern on the reticle may be damaged by static electricity. In this embodiment, since the charge of the reticle can be neutralized by neutralizing the charge by the action of the ionized inert gas, the circuit pattern of the reticle is not damaged by the static electricity.

In this embodiment, the third chamber 3 is in the atmosphere, but an exhaust system and a gas supply system are connected to the third chamber 3 to form an inert gas atmosphere in the third chamber 3. You may be able to do it. In the present embodiment, a two-arm transfer mechanism has been described as an example. However, it is apparent that a reticle exchange operation can be performed with one arm by installing a reticle standby table in the second chamber.

Further, in this embodiment, an example is shown in which nitrogen gas is used as an inert gas. However, if the inert gas does not have an oxygen absorption spectrum in the exposure wavelength region, a gas such as helium is used. You may. Further, the projection optical system PL can effectively apply the present invention to any of a reflection system, a catadioptric system, and a refraction system. As described above, in this embodiment, the first chamber that hermetically surrounds the first reticle to be projected and exposed, and the second chamber adjacent to the first chamber are provided. Between the first chamber and the second chamber, for example, a mechanical opening / closing mechanism (shutter)
Each chamber is connected to an exhaust system such as a vacuum pump and an inert gas supply system. A reticle transport mechanism is provided in the second chamber, and a second reticle to be projected and exposed next is in a standby state. As described above, the exposure apparatus of the present invention has two independent sealable chambers, and a desired inert gas atmosphere can be individually formed in each chamber. When replacing the reticle, first, the opening and closing mechanism between the first chamber and the second chamber is opened to communicate the first chamber and the second chamber, and then the reticle transport mechanism is operated to operate the first reticle and the second reticle.
Replace reticle. After the replacement of the reticle, the opening / closing mechanism is closed to cut off the communication between the first chamber and the second chamber. First
Since both the chamber and the second chamber are filled with the inert gas, the inert gas atmosphere in the first chamber is not broken during the above-described process. Further, since only a minimal gas flow is generated in the first chamber due to the transport of the reticle, a change in the refractive index of the atmosphere due to the gas flow is substantially avoided, and the reticle alignment operation is performed quickly. Therefore, the next projection exposure can be started immediately after the reticle exchange. During projection exposure with the replaced second reticle, the reticle transport mechanism is operated to replace the exposed first reticle remaining in the second chamber with a third reticle to be projected and exposed next. At this time, the inert gas atmosphere in the second chamber is broken, but a desired inert gas atmosphere may be re-formed using the time until the end of the projection exposure with the replaced second reticle.

[0035]

As described above, according to the exposure apparatus of the present invention,
A plurality of independent sealable spaces including a space surrounding the mask can be formed between the light source and the substrate, and an independent desired inert gas atmosphere can be formed for each space. In particular, when the reticle is replaced, the influence on the inert gas atmosphere in another space can be reduced.

According to another aspect of the present invention, static electricity in the reticle can be removed by setting the space for accommodating the reticle to an ionized inert gas atmosphere. Therefore, damage to the circuit pattern formed on the reticle is avoided, and the reliability of the device is significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a configuration of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a configuration of a reticle unit in FIG. 1;

FIG. 3 is a diagram showing an absorption spectrum of oxygen.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st chamber 2 2nd chamber 3 3rd chamber 4 Ionized gas generator 5 1st arm 6 2nd arm R Reticle RT Reticle table A Alignment part S1 Shutter S2 Shutter M Transport mechanism

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 502

Claims (7)

(57) [Claims] A first pattern formed by light from a light source ;
An illumination optical system that illuminates the mask, and an exposure apparatus that includes a projection optical system that transfers the image of the pattern onto a substrate , wherein the optical member on the substrate side of the projection optical system and the substrate
Atmosphere forming means for forming an inert gas atmosphere therebetween, a first container surrounding the illumination optical system, a second container surrounding the projection optical system, and a second container surrounding the first mask. One chamber, the first container, the second container, and the first chamber
In order to obtain the desired inert gas atmosphere individually,
The first container, the second container, and the first chamber;
An exposure apparatus comprising: a gas supply unit that supplies an inert gas to each of them. 2. A second mask exchanged with the first mask.
A second chamber is provided for holding a workpiece before transferring it to the first chamber.
The gas supply means supplies the inert gas to the second chamber.
The exposure apparatus according to claim 1, wherein the supply is performed . 3. The method according to claim 1, wherein the first container, the second container,
Each of the first chamber and the second chamber communicates with an exhaust system.
The exposure apparatus according to claim 2, wherein the exposure is performed. 4. The gas supply means comprises: the first container;
That of the second container, the first chamber, and the second chamber
An apparatus according to claim 2 or claim 3, characterized in that to supply the inert gas through the valve, respectively. 5. The atmosphere forming means holds the substrate.
A container surrounding the stage
An apparatus according to any one of claims 4 to Motomeko 1. 6. The exposure apparatus according to claim 2, further comprising an ionizing means for ionizing the inert gas supplied to the second chamber. 7. The exposure apparatus according to claim 1, wherein the inert gas is nitrogen or helium.