JP2003234281A - Exposure device, manufacturing method of device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the concentration of an inert gas in a vessel housing various kinds of members of an illumination system, a projection optical system, mechanical members or the like, and reduce the concentration of impurity gas generated from a resist applied on a wafer and reaching the projection optical system. <P>SOLUTION: An exposure device is constituted of a gas flow forming device which forms a local space for passing the inert gas in a light passage space including a space, through which exposure light between the projection optical system and a stage during exposing is passed, while a choking member is installed in the local space in a direction from the projection optical system toward the wafer. <P>COPYRIGHT: (C)2003,JPO

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 a device manufacturing method for projecting and transferring a pattern formed on a mask onto a substrate by using exposure light.

[0002]

2. Description of the Related Art In a photolithography process for manufacturing a semiconductor device or the like, an exposure apparatus is used which projects a pattern image of a mask (for example, a reticle) onto a photosensitive substrate through a projection optical system to expose it. In recent years, semiconductor integrated circuits have been developed in the direction of miniaturization, and in the photolithography process, the wavelength of the photolithography light source has been shortened.

However, vacuum ultraviolet rays, especially 250n
Light having a wavelength shorter than m, for example, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 19
3 nm), F ₂ laser (wavelength 157 nm), or YA
When light such as a harmonic of G laser is used as the exposure light, or when X-rays are used as the exposure light, the intensity of the exposure light is reduced due to the influence of the absorption of the exposure light by oxygen or the like. Was occurring.

Therefore, conventionally, in an exposure apparatus having a light source such as an F ₂ excimer laser, a sealed space for sealing only the optical path portion is formed, and for example, a gas containing no oxygen such as nitrogen is used to seal the sealed space. The gas was replaced to try to avoid a decrease in the transmittance of the exposure light.

11 and 12 show that an inert gas atmosphere is supplied to the space between the final optical member of the projection optical system (lens barrel) and the photosensitive substrate (wafer) by supplying the inert gas. It is a figure which shows the exposure apparatus which forms and exposes. In this exposure apparatus, a shielding member is provided around the space for separating the space above the exposure region and the atmosphere around the space, and an inert gas is supplied into the space from the periphery of the exposure region.

[0006]

However, as shown in FIG.
In the exposure apparatus shown in FIG. 1 and FIG. 12, the atmosphere accumulated in the steps or gaps around the wafer cannot be replaced with the inert gas until the atmosphere moves into the space. When the wafer stage moves at a high speed, the concentration decreases, and the inert gas concentration decreases due to the influence of entrainment, which causes uneven illuminance. Further, once the concentration of the inert gas in the space decreases, it takes time to return to the predetermined concentration of the inert gas, which causes a decrease in throughput.

Impurity gas such as organic gas is generated from the resist applied on the wafer. In the conventional exposure apparatus, the concentration of the impurity gas in the space cannot be sufficiently lowered, and the impurity gas causes a chemical reaction by the exposure light, which adheres to the lens of the projection optical system as contamination and causes a decrease in illuminance. Was there.

The same problem applies to the case where an inert gas is supplied to the periphery of the reticle, and when exposing the periphery of the reticle, the concentration of the inert gas in the space decreases and when the wafer stage moves at a high speed. The concentration of the inert gas was lowered due to the influence of entrainment in the sheet, which was a cause of uneven illuminance.

The present invention has been made in view of the above problems, and stabilizes the concentration of an inert gas in a container accommodating various members such as an illumination system, a projection optical system, and mechanical members, and further, An object of the present invention is to provide an exposure apparatus and a device manufacturing method capable of reducing the concentration of an impurity gas generated from a resist applied on a wafer and reaching a projection optical system.

[0010]

An exposure apparatus according to the present invention for achieving the above object comprises an optical path space including a substrate, a stage for holding the substrate, an optical system and a space between the stage during exposure. A gas flow forming device for forming a local space in which an inert gas flows, the gas flow forming device being placed on the optical system side with a narrow space between the substrate and the local space as compared with the local space. A diaphragm member is provided in the local space in the direction from the system to the substrate.

Further, preferably, the gas flow forming device is provided with an air supply port and an air discharge port facing each other in a location near the optical system in the local space, and the throttle member is a plate-shaped member and the air supply port outlet. Alternatively, it is installed on at least one substrate side of the exhaust port inlet in a direction substantially along the gas flow.

Further, preferably, the gas flow forming device is provided with two air supply ports opposed to a position in the local space near the optical system, and the throttle member is a plate-like member at the air supply port outlet. It is installed on the substrate side in a direction substantially along the gas flow.

Further, preferably, the gas flow forming device is provided with two air supply ports opposed to a position in the local space near the optical system, and an air supply device opposed to a position in the local space near the substrate. An aperture and an exhaust port are provided, and the throttle member is installed in the middle of the two pairs of air supply and exhaust ports in a direction substantially along the gas flow.

A device manufacturing method according to the present invention for achieving the above object has the following configuration. That is, the device manufacturing method includes a transfer step of transferring a pattern onto a wafer coated with a photosensitive material using an exposure apparatus, and a developing step of developing the wafer, the exposure apparatus forming a pattern. A projection optical system for projecting the exposure light applied to the reticle onto the wafer, a stage that holds the wafer and is movable on a plane, and an exposure light between the projection optical system and the stage during exposure. It comprises a gas flow forming device for forming a local space in which an inert gas flows in an optical path space including a space through which the diaphragm passes, and a diaphragm member is provided in the local space in a direction from the projection optical system to the wafer.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 and 2 are views showing a part of an exposure apparatus according to Embodiment 1 of the present invention. This exposure apparatus includes, for example, a light source that generates short-wavelength laser light such as an F ₂ excimer laser (not shown) as illumination light, and the illumination light (exposure light) of the light source is transmitted through an appropriate illumination optical member to a reticle. Illuminate (mask) uniformly. The light (exposure light) that has passed through the reticle passes through various optical members that make up the projection optical system and is transferred onto the surface of the wafer mounted on the wafer stage installed in the chamber having the air supply unit and the exhaust unit. Where the reticle pattern is imaged.

The wafer stage on which the wafer is placed has three wafer stages.
It is configured to be movable in the dimensional directions (XYZ directions).
The pattern of the reticle is sequentially projected and transferred onto the wafer by a so-called stepping and repeat method in which stepping movement and exposure are repeated. Moreover, even when the present invention is applied to a scan exposure apparatus, the configuration is almost the same.

At the time of exposure, an inert gas (for example, nitrogen gas, helium gas, etc.) whose temperature and impurity concentration are controlled with high accuracy is passed through an air supply valve to expose light in a gas flow forming device below the projection optical system. It is supplied from the air supply port to the local space including the space through which the air passes and its surroundings. A part of the inert gas supplied to the local space is recovered at the exhaust port and exhausted through the exhaust valve. The arrow in FIG. 1 indicates the flow of the inert gas.

Further, basically, the oxygen concentration of the exposure atmosphere in the local space is lowered by making the local space positive pressure with respect to the surrounding atmosphere. Therefore, the amount of the inert gas leaking from the local space to the peripheral space is larger than the exhaust amount exhausted through the exhaust valve. The inert gas leaking out of the local space is collected and exhausted by the exhaust unit together with the atmosphere in the chamber supplied from the air supply unit. In the chamber atmosphere, since the local space including the exposure atmosphere is highly accurately controlled in temperature and impurity concentration by the gas flow forming device,
The gas supplied from the air supply unit may be a gas having a relatively moderate temperature and impurity concentration controlled as long as allowed.

The opening and closing and the opening of the air supply valve and the exhaust valve are controlled by the environmental controller. Normally, the air supply valve and the exhaust valve are open, and the inert gas is always supplied into the local space regardless of the position of the stage. However, if the stage is removed from under the local space, such as during wafer replacement and maintenance, temporarily stop the supply of inert gas or reduce the supply amount, and before the stage re-enters the local space after wafer replacement. Supply started,
Alternatively, control for returning the supply amount may be performed.

The environment controller, the stage controller, and other controllers (not shown) are controlled by the main controller.
It is centrally controlled in various operations such as wafer exchange, alignment operation, and exposure operation. The control content of the main controller and the operating state of the exposure apparatus are monitored by the monitoring apparatus.

Here, since the inert gas leaked from the local space is caused to flow due to the atmosphere in the chamber as described above, it is entangled during the high speed movement of the wafer stage, and the atmosphere in the gaps / steps around the wafer is also increased. Was not replaced before entering the local space, and there was a possibility that the oxygen concentration in the local space would rise.

Therefore, in the first embodiment, in order to quickly reduce the oxygen concentration in the local space to within the set value, the gas flow forming device is installed on the projection optical system side with the wafer and the narrow space separated from each other. The distance H1 between the gas flow forming device in the narrow space and the wafer is about ⅕ or less of the distance H0 between the projection optical system in the local space and the wafer so that the oxygen concentration in the local space can be lowered more quickly within the set value. it can. Also, the length along the gas flow in a narrow space
It is likewise preferable to set L1 to be twice as long as H1 or longer.

The outer shape of the gas flow forming device may be a shape obtained by extending the cross section of the gas flow forming device in the depth direction of the paper surface of FIG. 1 or may be rotationally symmetrical with respect to the exposure optical axis. The shape is not limited to.

Further, in the local space, for example, an organic gas is generated from the resist applied to the wafer, the organic gas reacts with the exposure light, and the contamination adheres to the surface of the lens of the projection optical system, resulting in the clouding of the lens. There is a possibility that the intensity of the exposure light may be reduced.

Therefore, in the first embodiment, the exit of the air supply port in the local space is provided with a diaphragm member for reducing the cross-sectional area of a part of the local space in the direction from the projection optical system to the wafer. The squeezing member suppresses the generation of a vortex that the gas in the local space reaches from the wafer side to the projection optical system side about the direction perpendicular to the paper surface, and therefore the organic gas generated from the resist applied to the wafer is quickly discharged. Therefore, the concentration of the organic gas or the like reaching the lens of the projection optical system can be sufficiently reduced, and the clouding of the lens can be suppressed. Further, since the flow of the inert gas in the local space becomes smooth, as a result, the oxygen concentration in the local space can be lowered more quickly.

The location of the throttle member is not limited to the air supply side of the local space as shown in FIG. 2, but may be provided on the air discharge side as shown in FIG. 3, or as shown in FIG. It may be provided on both the exhaust side.

As a modification, as shown in FIG. 5, the exhaust mechanism of FIG. 2 may be changed to an air supply mechanism, and air supply ports facing each other in the local space may be provided with throttle members. In this case, the amount of inert gas supplied from each air supply port, the length and position of the throttle member need not be particularly symmetrical, and an asymmetrical structure as shown in FIG. 6 is more effective in preventing contamination.

Further, as another modification, as shown in FIG. 7, instead of providing a throttling member, the wafer side of the gas flow forming device near the outlet of the air supply port is shaved to widen a part of the narrow space. An effect equivalent to that of providing the diaphragm member can be expected.

Although the diaphragm member is fixed in these embodiments, a driving mechanism for moving the diaphragm member is added,
The diaphragm member may be moved depending on the exposure state. In this case, for example, it is possible to increase the projection amount of the diaphragm member during movement of the stage to prevent the concentration of the inert gas from decreasing, and reduce the projection amount of the diaphragm member to a position where the exposure light is not blocked during exposure. Is.

In this embodiment, the projection optical system, the wafer and the wafer stage have been specifically described. However, as shown in FIG. 13, the same can be applied to the illumination optical system, the reticle and the reticle stage. .

(Embodiment 2) In Embodiment 2, as shown in FIG. 8, two gas supply / exhaust systems of the gas flow forming apparatus are prepared, the projection optical system side is provided with two opposed air supply ports, and the wafer side is supplied with air. The air port and the exhaust port are opposed to each other, and the throttle member is provided in the middle of these two pairs of air supply and exhaust ports.

According to the above construction, the two opposing air supply ports and the diaphragm member on the projection optical system side suppress the impurity gas generated from the resist applied to the wafer and reaching the projection optical system, and the wafer side is suppressed. Impurity gas can be promptly discharged to the outside by the gas flow formed by the air supply port and the exhaust port.

(Application Example of Exposure Apparatus) Next, a semiconductor device manufacturing process using the above-described exposure apparatus will be described.

FIG. 9 shows the flow of the whole manufacturing process of the semiconductor device.

In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask making), a mask is made based on the designed circuit pattern. On the other hand, in step 3 (wafer manufacturing), a wafer 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 mask and wafer described above.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer manufactured in step 4, including an assembly process (dicing, bonding), a packaging process (chip encapsulation). Etc. including the assembling process. In step 6 (inspection),
Inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. The semiconductor device is completed through these processes, and is shipped in step 7.

FIG. 10 shows a detailed flow of the wafer process.

In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern is transferred onto the wafer by the above-mentioned exposure apparatus. In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. In step 19 (resist peeling), the unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

[0040]

As described above, according to the present invention,
Stabilizes the concentration of the inert gas in the container that houses the illumination system, projection optical system, and various members such as mechanical members, and further adjusts the impurity gas concentration generated from the resist applied to the wafer and reaching the projection optical system. Exposure equipment that can be lowered,
A device manufacturing method can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a part of an exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram in which the configuration of FIG. 1 of Embodiment 1 of the present invention is omitted.

FIG. 3 is a diagram showing a modification of the exposure apparatus of FIG. 2 according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a modification of the exposure apparatus of FIG. 2 according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a modification of the exposure apparatus of FIG. 2 according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a modification of the exposure apparatus of FIG. 2 according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a modification of the exposure apparatus of FIG. 2 according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a part of an exposure apparatus according to a second embodiment of the present invention.

FIG. 9 is a flowchart of the overall manufacturing process of a semiconductor device.

FIG. 10 is a flowchart of an overall manufacturing process of a semiconductor device.

FIG. 11 is a diagram showing a part of a conventional exposure apparatus.

FIG. 12 is a diagram showing a part of a conventional exposure apparatus.

FIG. 13 is a diagram showing an example in which a gas flow forming device is installed in a space between an illumination optical system and a reticle in the first embodiment of the present invention.

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Claims (7)

[Claims] 1. An exposure apparatus for projecting exposure light irradiated on a patterned reticle onto a wafer, a substrate, a stage for holding the substrate, an optical system and a space between the stage during exposure. A gas flow forming device that forms a local space in which an inert gas flows in an optical path space that includes the gas flow forming device, and the gas flow forming device is mounted on the optical system side with a narrow space between the substrate and the local space. An exposure apparatus comprising a diaphragm member in the local space in a direction from the optical system to the substrate. 2. The gas flow forming device comprises an air supply port and an air discharge port facing each other in a location near the optical system in the local space, and the throttle member is a plate-like member, and the gas supply port outlet or the gas exhaust port. The exposure apparatus according to claim 1, wherein the exposure apparatus is installed on at least one substrate side of the inlets in a direction substantially along the gas flow. 3. The gas flow forming device comprises two air supply ports facing each other in the local space near the optical system, and the throttle member is a plate-shaped member on the substrate side of the air supply port outlet. The exposure apparatus according to claim 1, wherein the exposure apparatus is installed substantially along a gas flow. 4. The gas flow forming device is provided with two air supply ports opposed to a position near the optical system in the local space, and an air supply port and an exhaust gas opposed to a position near the substrate in the local space. The exposure apparatus according to claim 1, further comprising an opening, wherein the diaphragm member is installed in the middle of the two pairs of air supply / exhaust openings in a direction substantially along the gas flow. 5. The exposure apparatus according to claim 1, wherein the substrate is a reticle, and the stage is a reticle stage. 6. The substrate according to claim 1, wherein the substrate is a wafer, and the stage is a wafer stage.
The exposure apparatus according to any one of 1. 7. A device manufacturing method, comprising: a transfer step of transferring a pattern onto a wafer coated with a photosensitive material using an exposure apparatus; and a developing step of developing the wafer,
The exposure apparatus comprises a substrate, a stage for holding the substrate, and a gas flow forming device for forming a local space in which an inert gas flows in an optical path space including a space between the optical system and the stage during exposure. The device for manufacturing a device, wherein the flow forming apparatus is mounted on the optical system side with a narrow space from the substrate, and a diaphragm member is provided in the local space in a direction from the optical system to the substrate.