JP2000021745A - Exposure equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To increase the efficiency of replacement with an inert gas in a lighting system container and minimize the time required for replacement of the atmosphere with an inert gas. An exposure apparatus that illuminates a mask via an illumination optical system with exposure light from an exposure light source and projects and exposes a pattern formed on the mask onto a photosensitive substrate via a projection optical system. An optical system disposed on the optical path of exposure light from the exposure light source to the mask is sealed in a container, and a specific gas is supplied into the container. The stirring fan is driven during supply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus that uses an ultraviolet ray or an excimer laser beam, which has a strong light flux and easily activates an atmospheric gas, as illumination light.

[0002]

2. Description of the Related Art In an exposure apparatus used for manufacturing a semiconductor, improvement in throughput and resolution has recently been demanded in order to make a pattern line width finer. Along with this, as the exposure light, an even higher illuminance is required, and the wavelength of the exposure light has been shortened.

However, in an exposure apparatus that uses i-line (wavelength λ = 365 nm) as exposure light and an exposure apparatus that uses exposure light having a shorter wavelength than i-line, the short-wavelength exposure light converts impurities in air into oxygen and photochemically. Is known to cause a reaction,
A product (cloudy substance) by such a reaction adheres to the glass member, and there is a disadvantage that opaque “clouding” occurs in the glass member. Here, as the cloudy substance, for example, ammonium sulfate (NH ₄ ) ₂ SO _{4, which} is generated when sulfurous acid (SO ₂ ) absorbs light energy to be in an excited state and reacts (oxidizes) with oxygen in the air, is exemplified. Can be This ammonium sulfate has a white tinge, and when adhered to the surface of an optical member such as a lens or a mirror, the above-mentioned "cloudy"
State. Then, the exposure light is scattered and absorbed by the ammonium sulfate, so that the transmittance of the optical system is reduced.

In particular, in a short wavelength region where the exposure light has a wavelength of 248 nm or less, which is shorter than the i-line, such as a KrF excimer laser, the exposure light causes a stronger photochemical reaction, and not only the above-mentioned "cloudiness" occurs, At the same time, there is a phenomenon in which the exposure light further reacts oxygen in the air to generate ozone, and both the residual oxygen and the generated ozone absorb the exposure light.

Therefore, an optical system such as a lens system or a projection lens system of a light source is housed in a container, and the air in the container is replaced with an inert gas such as nitrogen gas or another gas from which impurities have been removed. Methods for preventing contamination of each optical member have been developed.

[0006]

However, in recent years,
The illumination system of the exposure equipment is complicated and maintenance is indispensable to realize various illumination conditions and deformed illumination, and the space filled with inert gas is frequently exposed to outside air for work. Becomes In addition, many substances used as an inert gas are harmful to the human body, such as N ₂ and He ₂ . Therefore, it is necessary to ensure the safety by stopping the supply of the inert gas during the maintenance work. Therefore, the inside of the container is filled with the atmosphere during the maintenance work. Therefore, after the operation, it is necessary to replace the inert gas again. Similarly, when the exposure apparatus is stopped for a long period of time, replacement with an inert gas is required.

However, at present, the structure in the inert gas filling area in the illumination system is complicated, and there are many "stagnations" in which the inert gas is difficult to flow when the atmosphere is replaced with the inert gas. Since air accumulates in the stagnation and flows out little by little, the time until the inside of the container is completely replaced with the inert gas is significantly prolonged.

The present invention has been made in view of the above-mentioned unresolved problems of the prior art, and has been made to increase the efficiency of replacing a specific gas such as an inert gas in an illumination system container with a specific gas from the atmosphere. The purpose of the present invention is to minimize the time required for the replacement.

[0009]

In order to achieve the above object, a mask is illuminated by an exposure light from an exposure light source via an illumination optical system, and a pattern formed on the mask is projected via a projection optical system. An exposure apparatus that performs projection exposure on a photosensitive substrate, a container that seals an optical system disposed on an optical path of exposure light from the exposure light source to the mask, and a unit that supplies a specific gas into the container, It is characterized by having a fan for stirring the gas in the container and means for driving the stirring fan when supplying gas.

[0010]

By providing a fan in the gas filling space of the illumination system and driving it when replacing a specific gas from the atmosphere or the like, the flow velocity of the gas in the container is increased. As a result, the specific gas flows into the entire area inside the container, eliminating the air pool,
The specific gas to be replaced and the gas (atmosphere, etc.) that existed before that are mixed evenly in the entire region of the container. The mixed gas is discharged from the container through the discharge port, and a new pure specific gas is supplied from the supply port one after another,
The specific gas concentration uniformly rises throughout the space, and the replacement with the specific gas proceeds in a short time.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view for explaining a first embodiment. An exposure apparatus E1 according to the present embodiment uses an excimer laser (K).
rF, ArF, F _2, etc.), a light source lens system 2 as an optical system for shaping a laser beam L1 as illumination light emitted from the light source 1 into a light beam of a predetermined shape, and the light source lens system Laser light L formed into a predetermined shape by
1 comprises a projection lens system 6 for forming an image on a wafer W1 as a substrate via a reticle R1.

The light source lens system 2 includes a number of lenses and optical elements such as mirrors 4a and 4b, and illuminates an illumination area on the reticle with a uniform illuminance by the laser light L1 from the light source 1. The light source lens system 2 includes collimator lenses 5a and 5b, a fly-eye lens 8 as an optical integrator, and condenser lenses 7a, 7b and 7
c, constituted by subunits such as a blind unit 9 for defining the shape of the illumination area on the reticle R1. These light source lens systems 2 are disposed inside a container 3, and the inside of the container 3 is connected to a nitrogen gas supply device 11, a nitrogen gas supply line 12, and a nitrogen gas supply line 12 for supplying nitrogen gas which is an inert gas. It is connected via an electromagnetic valve 13 which is an on-off valve provided. Further, a gas exhaust line 15 and a solenoid valve 16 are connected to a gas exhaust device 14 for exhausting gas in the container 3.
Connected via A throttle valve may be provided instead of the solenoid valve.

The operation timing of the nitrogen gas supply device 11 and the gas exhaust device 14 is determined by the controller 10.
This is performed by the program set in.

During normal operation of the exposure apparatus, the solenoid valves provided in the nitrogen gas supply line 12 and the gas exhaust line 15 are set to be open continuously or intermittently so that the nitrogen gas is always replaced. You. When the optical components are arranged as described above, there are places such as 17a to 17e where nitrogen hardly flows. Reference numeral 18 denotes a gas stirring fan, and 19 denotes a fan driving circuit, which is driven and controlled by the controller 10. Container 3 for maintenance or other reasons
When the air conditioner is opened, the atmosphere flows into the container 3.
When operating the exposure apparatus again, it is necessary to replace the atmosphere in the container 3 from the atmosphere with an inert gas. In this case, nitrogen is supplied while the container 3 is sealed and the gas stirring fan 18 is rotated. This makes it difficult for nitrogen to flow in 17a-17.
A flow is forcibly created also at the portion e, and the atmosphere and nitrogen are easily mixed.

The inert gas is not limited to nitrogen,
Helium or the like may be used. In addition, a specific active gas such as clean dry air or ozone for cleaning optical members may be used instead of the inert gas.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. Here, the same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted. In the first embodiment, a fan is provided at one location to increase the flow rate of gas in the entire container, whereas in the second embodiment, one or one fan is directly provided at places 17a to 17e where air pools are expected to be formed. A plurality of gas stirring fans 18 are arranged to more reliably remove air pools.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. Here, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted. In the third embodiment, a wind direction control plate 20 is provided in front of the gas stirring fan 18 of the first embodiment.
By moving the control unit 21 at a fixed cycle or a random cycle by the control unit 21, the atmosphere and the nitrogen can be more uniformly stirred.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. Here, the above-mentioned first to first
Parts common to the third embodiment are denoted by the same reference numerals, and description thereof will be omitted. The fourth embodiment is different from the third embodiment in that the wind direction control plate 2 attached in front of the gas stirring fan 18 is used.
0 is controlled through the control unit 21 in accordance with the values of the oximeters 22 installed at a plurality of positions to encourage more positive and uniform mixing of the atmosphere and nitrogen.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIG. Here, the above-mentioned first to first
The same parts as in the fourth embodiment are denoted by the same reference numerals, and description thereof will be omitted. The fifth embodiment is the first to fifth embodiments.
Except when the gas agitating fan 18 of the fourth embodiment is being driven, the gas agitating fan 18 is isolated from the nitrogen-filled space in which the optical components are present by a partition 23. The motors and cables themselves can be sources of contaminants and are isolated from the space through which the laser passes.

(Embodiment of Device Production Method) Next, an embodiment of a device production method using the above-described exposure apparatus will be described. FIG. 6 shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micromachines, etc.). Step 1
In (Circuit Design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. Step 3 (wafer manufacturing)
Then, a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process,
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. 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. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 7 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 exposure apparatus having the gas replacement mechanism described above 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 production method of this embodiment, it is possible to produce a highly integrated device, which was conventionally difficult to produce, at low cost.

[0023]

As described above, according to the present invention, when the gas filling space is replaced with a specific gas from the atmosphere or the like, the gas in the container is agitated by the gas agitating fan and the gas in the entire space in the container is made uniform. As a result, it is possible to perform reliable replacement in a shorter time without leaving air pockets. As a result, even after exposing the gas-filled space to the atmosphere for maintenance or the like, the replacement with the specific gas is completed earlier, and the exposure apparatus can be quickly returned to the operable state. Can be held down.

[Brief description of the drawings]

FIG. 1 is a view schematically showing an overall configuration of an exposure apparatus according to a first embodiment.

FIG. 2 is a view schematically showing an overall configuration of an exposure apparatus according to a second embodiment.

FIG. 3 is a diagram illustrating an example of a specific configuration of a maintenance space of an exposure apparatus according to a third embodiment.

FIG. 4 is a diagram illustrating an example of a specific configuration of a maintenance space of an exposure apparatus according to a fourth embodiment.

FIG. 5 is a diagram illustrating an example of a specific configuration of a maintenance space of an exposure apparatus according to a fifth embodiment.

FIG. 6 is a diagram showing a flow of manufacturing a micro device.

FIG. 7 is a diagram showing a detailed flow of a wafer process in FIG. 6;

[Explanation of symbols]

E1: Excimer laser stepper, L1: Laser beam, R
1: reticle, W1: wafer, 1: light source, 2: light source lens system, 3: container, 4a, 4b: mirror, 5a, 5b: collimator lens, 6: projection lens system, 7a to 7c: condenser lens, 8: Fly-eye lens, 9: blind part, 10: controller, 11: nitrogen gas supply device, 1
2: nitrogen gas supply line, 13: solenoid valve, 14: gas exhaust device, 15: gas exhaust line, 16: solenoid valve, 17a
17e: a place where nitrogen hardly flows, 18: a gas stirring fan, 19: a fan drive power supply unit, 20: a wind direction control plate, 21: a wind direction control plate control unit, 22: an oxygen concentration meter, 23: a partition wall.

Claims (7)

[Claims] An exposure apparatus that illuminates a mask via an illumination optical system with exposure light from an exposure light source and projects and exposes a pattern formed on the mask onto a photosensitive substrate via a projection optical system. A container for enclosing an optical system disposed on an optical path of exposure light from the exposure light source to the mask, a unit for supplying a specific gas into the container, a fan for stirring gas in the container, and a gas supply Means for driving the stirring fan at times. 2. The exposure apparatus according to claim 1, wherein the specific gas is an inert gas or a specific active gas. 3. The exposure according to claim 1, further comprising a wind direction control mechanism attached to the stirring fan, and means for moving the wind direction control mechanism at a constant or random cycle. apparatus. 4. A gas concentration meter having a plurality of gas meters at a plurality of positions in the container, and means for moving the wind direction control mechanism controls a wind direction according to a concentration value measured by the gas concentration meter and a measurement position. The exposure apparatus according to claim 3, wherein: 5. The exposure apparatus according to claim 1, further comprising: a unit that isolates the gas stirring fan from a space where the optical component exists except during operation. . 6. The exposure apparatus according to claim 1, wherein the exposure light source includes an excimer laser. 7. A device manufacturing method, comprising manufacturing a device using the exposure apparatus according to claim 1.