JP2004134567A - Aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the invasion of external gas into a purge chamber through an opening provided on the purge chamber for the movement, operation or the like of an object. <P>SOLUTION: A space 30 for passing exposure light of far ultraviolet ray or the like is surrounded by the purge chamber 8. A transfer band 22 for transferring a reticle is arranged in the purge chamber 8 while a driving unit 21 for driving the transfer band 22 is arranged at the outside of the purge chamber 8. The opening 8a is formed on the purge chamber 8 while the transfer band 22 and the driving unit 21 are connected by a driving shaft 20 passing through the opening 8a. A gas supplying unit 19 for supplying an inert gas to the opening 8a is provided at the vicinity of the opening 8a, and the invasion of external gas of the purge chamber 8 through the opening 8a is prevented by the inert gas injected from the gas supplying unit 19. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exposure apparatus that transfers a pattern onto a substrate using exposure light, and a device manufacturing method using the exposure apparatus.
[0002]
[Prior art]
2. Description of the Related Art In a manufacturing process of a semiconductor device formed of an ultra-fine pattern such as an LSI or a super LSI, a reduced projection exposure apparatus is used in which a circuit pattern drawn on a mask is reduced and projected onto a substrate coated with a photosensitive agent and printed. ing. As the packaging density of semiconductor devices has increased, further miniaturization of patterns has been demanded, and the development of resist processes has responded to the miniaturization of exposure apparatuses.
[0003]
Means for improving the resolving power of the exposure apparatus include a method of changing the exposure wavelength to a shorter wavelength and a method of increasing the numerical aperture (NA) of the projection optical system.
[0004]
Regarding the exposure wavelength, a transition is being made from the i-line of 365 nm to a KrF excimer laser having an oscillation wavelength of around 248 nm, and an ArF excimer laser having an oscillation wavelength of around 193 nm and fluorine (F ₂ ) having an oscillation wavelength of around 157 nm. Excimer lasers are being developed.
[0005]
In a deep ultraviolet ray, in particular, in an ArF excimer laser having a wavelength of around 193 nm or a fluorine (F ₂ ) excimer laser having an oscillation wavelength of around 157 nm, a plurality of oxygen (O ₂ ) absorption bands exist in the band near these wavelengths. It is known.
[0006]
For example, a fluorine excimer laser has a short wavelength of 157 nm, and is being applied to an exposure apparatus. The wavelength of 157 nm is in a wavelength range generally called vacuum ultraviolet. In this wavelength range, the atmosphere hardly transmits light due to the large absorption of light by oxygen molecules.Therefore, fluorine excimer lasers can be applied only to environments where the pressure is reduced to a pressure close to vacuum and the oxygen concentration is sufficiently reduced. Can not. According to the document “Photochemistry of Small Molecules” (written by Hideo Okabe, A Wiley-Interscience Publication, 1978, p. 178), the absorption coefficient of oxygen at a wavelength of 157 nm is about 190 atm ⁻¹ cm ⁻¹ . This means that when light having a wavelength of 157 nm passes through a gas having an oxygen concentration of 1% at 1 atm, the transmittance per 1 cm is:
T = exp (−190 × 1 cm × 0.01 atm) = 0.150
To indicate that there is only one.
[0007]
Oxygen (O ₃ ) is generated by absorption of light by oxygen, and this ozone further increases light absorption and remarkably lowers transmittance. Attaches to the surface and reduces the efficiency of the optical system.
[0008]
Therefore, in the optical path of the exposure optical system of the projection exposure apparatus using far ultraviolet rays as a light source, such as an ArF excimer laser or a fluorine (F ₂ ) excimer laser, oxygen present in the optical path is purged by an inert gas such as nitrogen. A method has been adopted in which the concentration is suppressed to a low level of several ppm or less.
[0009]
As described above, in an exposure apparatus using far ultraviolet light, particularly an ArF excimer laser having a wavelength of around 193 nm or a fluorine (F ₂ ) excimer laser having a wavelength of around 157 nm, ArF excimer laser light or fluorine (F ₂ ) is used. Since the excimer laser light is very easily absorbed by the substance, it is necessary to purge the optical path in the order of several ppm or less. The same can be said for water, and it is necessary to remove the water on the order of ppm or less.
[0010]
For this reason, in order to ensure the transmittance or stability of ultraviolet light, the ultraviolet light path around the reticle stage and wafer stage of the exposure apparatus is purged with an inert gas.
[0011]
When a member such as a reticle or a wafer is transferred into such a purge space (a space to be purged), a structure that allows the transfer hand to enter the purge space is employed, or the transfer hand is inserted into the purge space. Need to be placed.
[0012]
In a general transport hand, a lubricant such as grease is used for a guide or an actuator of a drive unit for driving the transport hand. Since the use of such a lubricant may cause a reduction in the purity of the inert gas in the purge space, the driving unit should be provided outside the purge space.
[0013]
Therefore, means for shielding the purge space in which the transfer hand is to be disposed and the space outside the purge target space in which the drive unit of the transfer hand is disposed is required.
[0014]
Conventionally, a bellows (bellows) made of a fluororesin material or the like has been used as such a shielding means.
[0015]
[Problems to be solved by the invention]
However, a structure in which a bellows is connected to a movable part such as a transfer hand has a problem that the bellows acts as a load on a driving unit and the durability of the bellows is low.
[0016]
The present invention has been made based on the recognition of the above problems, and for example, prevents external gas from entering the purge chamber through an opening provided in the purge chamber for moving or manipulating an object. The purpose is to do.
[0017]
[Means for Solving the Problems]
A first aspect of the present invention relates to an exposure apparatus that transfers a pattern to a substrate using exposure light, the apparatus includes a purge chamber surrounding a space through which the exposure light passes, and a movable body disposed in the purge chamber. A drive unit disposed outside the purge chamber to drive the movable body, a drive shaft connecting the movable body and the drive unit through an opening formed in the purge chamber, and an inert gas in the opening. And a gas supply unit for preventing gas from flowing from outside of the purge chamber to inside of the purge chamber through the opening. Although the exposure light is not particularly limited, for example, a fluorine excimer laser light, an ArF excimer laser light, or the like is preferable.
[0018]
According to a preferred embodiment of the present invention, it is preferable that the gas supply unit includes one or a plurality of nozzles for injecting gas toward the drive shaft.
[0019]
According to a preferred embodiment of the present invention, it is preferable that the driving section is configured to rotate and / or go straight on the driving shaft.
[0020]
According to a preferred embodiment of the present invention, it is preferable that the gas supply unit is configured to function as a hydrostatic bearing provided in the opening so as to guide the drive shaft.
[0021]
According to a preferred embodiment of the present invention, the apparatus further comprises a sensor for detecting a pressure in the purge chamber, wherein the gas supply unit controls supply of the inert gas to the opening based on an output of the sensor. It is preferable that it is comprised so that it may be.
[0022]
According to a preferred embodiment of the present invention, the apparatus preferably includes a purge mechanism for purging a gas in the purge chamber with an inert gas, separately from the gas supply unit.
[0023]
According to a preferred embodiment of the present invention, the apparatus further comprises a cleaning mechanism for supplying a cleaning gas (for example, oxygen and / or ozone) for cleaning the inside of the purge chamber into the purge chamber. Is preferred.
[0024]
According to a preferred embodiment of the present invention, the inert gas preferably includes at least one of nitrogen gas, helium gas, and argon gas.
[0025]
A second aspect of the present invention relates to an exposure apparatus that transfers a pattern to a substrate with exposure light, the apparatus including a purge chamber surrounding a space through which the exposure light passes, and an opening formed in the purge chamber. By supplying an inert gas to the opening and the movable body configured to be able to enter and exit the purge chamber, it is possible to prevent gas from flowing from the outside of the purge chamber to the inside of the purge chamber through the opening. And a gas supply unit.
[0026]
A third aspect of the present invention relates to a device manufacturing method, comprising a step of transferring a pattern to a substrate using an exposure apparatus having any of the above-described features, and a step of developing the substrate. I do.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is applicable to any exposure apparatus in which the optical path of exposure light should be an inert gas atmosphere.However, the present invention is particularly applicable to an exposure apparatus that uses ultraviolet light as exposure light, particularly far ultraviolet light. Useful. As the far ultraviolet light, an ArF excimer laser light having a wavelength around 193 nm and a fluorine (F ₂ ) excimer laser light having a wavelength around 157 nm are typical.
[0028]
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[0029]
[First Embodiment]
FIG. 1 is a diagram showing a schematic configuration of a step-and-scan type projection exposure apparatus according to a preferred embodiment of the present invention. In FIG. 1, ultraviolet light introduced from an unillustrated ultraviolet light source into an illumination system 1 in an exposure apparatus illuminates a reticle 6 mounted on a reticle stage 7. A cover 4 surrounding the ultraviolet light path is provided from the lower end of the illumination optical system 1 on the reticle side to the vicinity of the reticle stage 7, and inside the cover 4, an inert gas (for example, nitrogen gas) serving as a purge gas is provided inside the cover 4. , A helium gas, an argon gas, or a mixed gas of two or more of them.
[0030]
By supplying an inert gas from inside the illumination optical system 1 to the space inside the cover 4 (the inside purge space) through the nozzle 2, impurities (exposed harmful substances) such as oxygen and moisture existing inside the cover 4 are removed. Purging can be performed with the inert gas. Further, the inert gas is supplied to the space (outside purge space) 30 surrounded by the purge chamber 8 outside the cover 4 through the supply port 16 and the inert gas is recovered from the recovery port 17 so that the inside of the purge chamber 8 can be recovered. Impurities can be further reduced to a lower concentration.
[0031]
In order to transfer the reticle 6 to the reticle stage 7, a transfer hand (movable body or moving body) 22 is disposed in the purge chamber 8. The reticle 6 may be transported from, for example, a reticle stocker disposed in the purge chamber 8, may be transported from a reticle stocker connected to the purge chamber 8, or may be disposed outside the purge chamber 8. The reticle may be transported from the reticle stocker via a reticle delivery box connected to the purge chamber 8.
[0032]
The drive unit 21 that drives the transfer hand 22 generally has bearings, guides, and the like, and uses grease for lubrication of these. It is desirable that the drive unit 21 is disposed outside the purge chamber 8 so that the grease does not become a source of impurities. Therefore, in this embodiment, the drive unit 21 is disposed outside the purge chamber 8, the opening 8 a is provided in the purge chamber 8, and a drive shaft (for example, a rotating shaft and a vertical shaft) 20 passing through the opening 8 a is provided. The transport hand 22 and the drive unit 21 are connected to each other.
[0033]
As shown in FIGS. 1 and 2, an inert gas (for example, a nitrogen gas, a helium gas, an argon gas, or a mixed gas of two or more thereof) is supplied to the opening 8a in the vicinity of the opening 8a. A gas supply port 19 is provided. Here, the gas supply port 19 has at least one nozzle, preferably a plurality of nozzles 19-1 to 19-4, and is preferably configured to inject an inert gas toward the drive shaft 20. By supplying an inert gas from the nozzles 19-1 to 19-4 to the opening 8a, it is possible to prevent a gas such as air from flowing into the purge chamber 8 from the outside to the inside through the opening 8a. Here, the gas such as air may contain impurities using the driving unit 21 as an impurity source. The gas supply port 19 may be provided outside the purge chamber 8 and near the opening 8a, or may be provided inside the purge chamber 8 and near the opening 8a.
[0034]
The drive shaft 20 can be guided by a contact-type bearing such as a rolling bearing, for example, but may also be guided by a hydrostatic bearing. In the latter case, the gas supply port 19 can be configured as a static pressure bearing, and can be attached near the opening 8a of the purge chamber 8. In this case, the gas supply port 19 has a function of sealing the purge chamber 8 and a function of guiding the drive shaft 20.
[0035]
The ultraviolet light transmitted through the reticle 6 enters the wafer 14 placed on the wafer stage 13 via the projection optical system 9. A cover 12 surrounding the ultraviolet light path is provided from the lower end of the projection optical system 9 on the wafer side to the vicinity of the wafer stage 13. Inside the cover 12, an inert gas (for example, nitrogen gas) serving as a purge gas is provided inside the cover 12. , A helium gas, an argon gas, or a mixed gas of two or more of them.
[0036]
By supplying an inert gas from the inside of the projection optical system 9 to the space inside the cover 12 (the inside purge space) through the nozzle 10, impurities (exposed harmful substances) such as oxygen and moisture existing inside the cover 12 are removed. Purging can be performed with the inert gas. As a result, impurities inside the cover 12 can be sufficiently removed, but the inert gas is also supplied to a space (outer purge space) 15 surrounded by the partition wall 27 outside the cover 12 through a supply port (not shown). May be supplied. Thereby, the impurities inside the cover 12 can be removed at a lower concentration.
[0037]
Here, the space 15 outside the cover 12 is a space surrounded by the projection optical system base 25 and the wafer stage base 26 in addition to the partition wall 27. It is preferable that the partition wall 27 be a bellows-like elastic body so that vibration and deformation from the wafer stage base 26 to the projection optical system base 25 are hardly transmitted. Alternatively, the partition wall 27 may be formed of a rigid body instead of a bellows shape, and a small gap may be provided over the entire circumference without connecting the partition wall 27 and the projection optical system base 25. As a result, since the inert gas leaks to the outside through the gap, an extra flow rate is required, but the transmission of vibration and deformation from the wafer stage base 26 to the projection optical system base 25 is reduced. Alternatively, a configuration may be adopted in which the stage damper 28 is eliminated, the partition 27 is formed of a rigid body instead of a bellows shape, and the wafer stage base 26 is suspended from the projection optical system base 25 by the partition 27.
[0038]
According to this embodiment, the drive unit 21 as an impurity source is disposed outside the purge chamber 8 and the drive unit 21 and the transfer hand 22 are connected to each other by the drive shaft 20 through the opening 8a. Impurities can be reduced. Further, by supplying an inert gas from the gas supply port 19 to the opening 8 a of the purge chamber 8, it is possible to prevent gas such as air (outside air) from entering the inside of the purge chamber 8 from the outside. Such a mechanism could be understood as an inert gas air curtain.
[0039]
Therefore, according to this embodiment, it is possible to reduce impurities or harmful substances in the optical path, which are problematic when using ultraviolet light, particularly far ultraviolet light, as exposure light. Thereby, the transmittance of the exposure light can be stably maintained, and the adhesion of impurities or exposure harmful substances to the optical element or the like arranged in the optical path, the deterioration of the optical element, and the like can be suppressed.
[0040]
Although the above embodiments relate to a step-and-scan type exposure apparatus, the present invention can be applied to other exposure apparatuses, for example, a step-and-repeat type exposure apparatus.
[0041]
Further, in the above embodiment, gas such as air is prevented from entering the inside of the purge chamber 8 from the outside through the opening 8a formed in the purge chamber 8 surrounding the optical path on the reticle stage side. The same idea can be applied to, for example, a partition wall 27 (purge chamber) surrounding an optical path on the wafer stage 13 side. That is, an opening for passing a moving body such as a drive shaft through the partition wall 27 and a gas supply unit for supplying an inert gas to the opening may be provided.
[0042]
Further, in the above-described embodiment, the configuration in which the drive shaft 8a is always present in the opening 8a is described. However, the present invention relates to a moving mechanism configured to be able to move in and out of the purge chamber 8 through the opening 8a. It is also applicable to configurations having a body.
[0043]
[Second embodiment]
This embodiment provides a modification of the first embodiment. In this embodiment, as shown in FIG. 3, a pressure sensor 23 for detecting a pressure in a space (outer purge space) 30 in the purge chamber 8 and an opening (pressure value) based on the output (pressure value) of the pressure sensor 23 are provided. A gas supply control unit 24 for controlling the supply of the inert gas to the unit 8a is added. Here, the gas supply control unit 24 adjusts the pressure in the purge chamber 8 to the external pressure by adjusting, for example, the flow rate or pressure of the inert gas supplied to the gas supply port 19 based on the output of the pressure sensor 23. Is kept constant regardless of the fluctuation of
[0044]
Hereinafter, effects of such control will be described. The inside of the lens barrel of the illumination optical system 1 and the projection optical system 9 is also purged with an inert gas to remove impurities (exposed harmful substances) and is almost a closed system. Therefore, when the external pressure fluctuates, a pressure difference may occur between the illumination optical system 1 and the outside and between the inside and the outside of the lens barrel. Therefore, for example, the sheet glass 5 arranged at the lower end of the illumination optical system 1 or the sheet glass 18 arranged at the lower end of the projection optical system 9 is deformed according to the pressure difference, and the optical performance changes. is there.
[0045]
Therefore, in this embodiment, the pressure in the space (outside purge space) 30 in the purge chamber 8 is controlled to be constant, so that the space between the illumination optical system 1 and the outside and the inside and the outside of the lens barrel as described above. No pressure difference is generated, and a change in optical performance due to atmospheric pressure fluctuation is suppressed.
[0046]
[Third Embodiment]
This embodiment provides a modification of the first and second embodiments. In the first and second embodiments, only the supplied inert gas into the purging chamber 8 and the like, this embodiment, as shown in FIG. 4, oxygen as the cleaning gas in inert gas (O ₂ ) And / or a mechanism for mixing ozone (O ₃ ).
[0047]
At the time of normal exposure, the inert gas is supplied to the purge chamber 8 or the like by closing the valve 104 without mixing a cleaning gas such as oxygen and / or ozone with the inert gas.
[0048]
On the other hand, at an appropriate timing other than the time of the normal exposure, for example, at a standby time when the exposure apparatus is not operating, or during the normal exposure at specified time intervals, or when the reticle is mounted on the reticle stage By opening the valve 104, a trace amount of a cleaning gas such as oxygen and / or ozone is mixed with an inert gas and supplied to the purge chamber 8 or the like, and the dummy exposure is performed without loading the wafer onto the wafer stage 13. The operation is performed for a certain period of time or until a prescribed image plane illuminance is reached.
[0049]
Hereinafter, the effect of such control will be described. Exposure wavelength is far ultraviolet, especially in short wavelength exposure light such as ArF excimer laser light or fluorine excimer laser light, the exposure light decomposes impurities such as organic molecules in gas, and carbon film or A carbon-containing film, ie, an organic compound, is deposited. Therefore, the transmittance of the optical element gradually decreases, and the illuminance of the image surface decreases, which causes a decrease in throughput.
[0050]
In the first and second embodiments, the space in which the reticle 6 and the wafer 14 are arranged is purged with an inert gas to reduce the impurity concentration to the utmost limit. There is. Further, for example, during or before exposure, degassing occurs from the resist applied to the wafer or the adhesive layer between the resist and the wafer, and impurities are generated in the vicinity of the sheet glass 18 at the lower end of the projection optical system 9. May be present. Further, for example, a reticle to which a trace amount of impurities is attached is carried in and the impurities are partially evaporated, or degassed from an adhesive layer between the reticle and the pellicle frame or from an adhesive layer between the reticle frame and the pellicle. In some cases, the impurities are present near the exposure surface of the reticle, the sheet glass 5 at the lower end of the illumination optical system 1, or the optical element surface at the upper end of the projection optical system 9. In these cases, the organic compounds decomposed and generated by the light exposure adhere to and accumulate on these optical elements, and the transmittance of the optical elements gradually decreases.
[0051]
Therefore, if a small amount of ozone is mixed with an inert gas and the purge space is purged, and these optical elements are irradiated with exposure light, the organic compounds deposited by the so-called ozone cleaning effect are oxidized and decomposed, and the decomposition products are further decomposed. Is prevented from being formed. Alternatively, when exposure light is irradiated to those optical elements in a state where a small amount of oxygen is mixed with an inert gas and purged, oxygen is converted to ozone by a photochemical reaction, and thus ozone cleaning is performed in the same manner as when ozone is mixed. The effect is obtained. Therefore, by performing this between the exposures as described above, it is possible to prevent a decrease in image plane illuminance and maintain a high throughput at all times.
[0052]
[Application example of exposure apparatus]
Next, a manufacturing process of a semiconductor device using the above exposure apparatus will be described. FIG. 5 is a diagram showing a flow of the entire semiconductor device manufacturing process. In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask fabrication), a mask is fabricated 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 referred to as a pre-process in which an actual circuit is formed on the wafer by lithography using the above-described 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 assembly such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). 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. Through these steps, a semiconductor device is completed and shipped (step 7).
[0053]
FIG. 6 is a diagram showing 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. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to transfer a circuit pattern onto a wafer. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. Step 19 (resist stripping) removes unnecessary resist after etching. By repeating these steps, multiple circuit patterns are formed on the wafer.
[0054]
【The invention's effect】
According to the present invention, it is possible to prevent external gas from entering the purge chamber through an opening provided in the purge chamber for moving or manipulating an object, for example.
[Brief description of the drawings]
FIG. 1 is a view schematically showing a configuration of a projection exposure apparatus according to a preferred embodiment of the present invention.
FIG. 2 is a plan view schematically showing the vicinity of an opening provided in a purge chamber.
FIG. 3 is a view showing a pressure maintaining mechanism of a purge chamber according to a preferred embodiment of the present invention.
FIG. 4 is a diagram schematically showing a gas supply system according to a preferred embodiment of the present invention.
FIG. 5 is a diagram showing a flow of an overall semiconductor device manufacturing process.
FIG. 6 is a diagram showing a detailed flow of a wafer process.
[Explanation of symbols]
1: illumination optical system, 2: nozzle, 3: flow of inert gas (purge gas), 4: cover, 5: sheet glass, 6: reticle, 7: reticle stage, 8: purge chamber, 8a: opening, 9 : Projection optical system, 10: nozzle, 11: flow of purge gas, 12: cover, 13: wafer stage, 14: wafer, 15: purge area, 16: supply port, 17: recovery port, 18: sheet glass, 19: Gas supply unit, 19-1 to 19-4: nozzle, 20: drive shaft, 21: drive unit, 22: transport hand, 23: pressure sensor, 24: gas supply control unit, 25: projection optical system surface plate, 26 : Wafer stage surface plate, 27: partition, 28: stage damper, 101: inert gas supply source, 102: cleaning gas supply source, 103: valve, 104: valve

Claims (1)

An exposure apparatus that transfers a pattern onto a substrate with exposure light,
A purge chamber surrounding a space through which the exposure light passes;
A movable body disposed in the purge chamber;
A driving unit disposed outside the purge chamber and driving the movable body;
A drive shaft connecting the movable body and the drive unit through an opening formed in the purge chamber;
A gas supply unit that supplies an inert gas to the opening to prevent a gas from flowing from outside the purge chamber to the inside of the purge chamber through the opening;
An exposure apparatus comprising:

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