JP2004047893A - Exposure system and pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the deterioration of a resist pattern which is caused by outgas from a resist film that has been subjected to pattern exposure. <P>SOLUTION: A wafer stage 3 for supporting a wafer 4 is provided at the bottom of a chamber 1. A first exposure optical system 5 for forming patterns, and a second exposure optical system 6 for detecting the outgas, are provided above the wafer stage 3. The optical system 5 carries out pattern exposure by selectively irradiating the resist film formed on the wafer 4 with extreme ultraviolet rays. The second optical system 6 carries out test exposure by locally irradiating the periphery of the resist film formed on the wafer 4 with extreme ultraviolet rays. An outgas detection means 7 for detecting the rate of the outgas from the resist film is provided at the side of the chamber 1. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exposure apparatus and a pattern forming method used in a semiconductor device manufacturing process or the like.
[0002]
[Prior art]
With the increasing integration of semiconductor integrated circuits and downsizing of semiconductor elements, accelerated development of lithography technology is desired. At present, pattern formation is performed by photolithography using a mercury lamp, a KrF excimer laser, an ArF excimer laser, or the like as exposure light, but a fine pattern having a rule of 0.1 μm or less, particularly a rule of 70 nm or less is used. to form has a wavelength shorter _{F 2} laser (wavelength: 157 nm band) such as a vacuum ultraviolet or extreme ultraviolet: with the application of (wavelength 1nm band ~30nm band) have been studied, such as EB projection exposure EB Is being considered for application.
[0003]
Hereinafter, a conventional pattern forming method using extreme ultraviolet light as exposure light will be described with reference to FIGS. 4 (a) to 4 (d).
[0004]
First, a chemically amplified resist material having the following composition is prepared.
[0005]
Poly ((t-butyl methacrylate)-(mevalonic lactone methacrylate)) (provided that t-butyl methacrylate: mevalonic lactone methacrylate = 50 mol%: 50 mol%) (base polymer) …………………… 2g
Triphenylsulfonium triflate (acid generator) 0.08 g
Propylene glycol monomethyl ether acetate (solvent) 20 g
[0006]
Next, as shown in FIG. 4A, a chemically amplified resist material having the above composition is applied on the substrate 100 to form a resist film 101 having a thickness of 0.2 μm. As shown in FIG. 4B, the resist film 101 is selectively irradiated with extreme ultraviolet rays (wavelength: 13.5 nm band) 102 to perform pattern exposure.
[0007]
Next, as shown in FIG. 4C, when the substrate 100 is heated on a hot plate at a temperature of 100 ° C. for 60 seconds, an acid is generated from the acid generator in the exposed portion 101a of the resist film 101, so that the alkaline region is heated. While it changes to be soluble in the developing solution, no acid is generated from the acid generator in the unexposed portion 101b of the resist film 101, so that it remains poorly soluble in the alkaline developing solution.
[0008]
Next, when the resist film 101 is developed with a 2.38 wt% tetramethylammonium hydroxide developing solution (alkaline developing solution), as shown in FIG. Thus, a resist pattern 103 having a line width of 0.07 μm is obtained.
[0009]
[Problems to be solved by the invention]
However, the cross-sectional shape of the resist pattern obtained by the conventional pattern forming method has deteriorated. When the film to be processed is etched using the resist pattern having the deteriorated shape as a mask, the shape of the obtained pattern is also deteriorated.
[0010]
By the way, in order to perform pattern exposure using extreme ultraviolet rays, it is necessary that the amount of outgas released from the pattern-exposed resist film is small. That is, when a large amount of outgas is released from the resist film, the outgas adheres to the mirror or mask of the exposure optical system and the illuminance of the exposure light decreases, so that the accuracy of the resist pattern is deteriorated or the throughput is reduced. I do.
[0011]
Therefore, in the conventional pattern forming method, it is considered that the outgas released from the resist film adheres to the exposure optical system, and the shape of the resist pattern is degraded.
[0012]
In view of the above, an object of the present invention is to prevent a situation in which the shape of a resist pattern is degraded due to outgas released from a resist film subjected to pattern exposure.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, an exposure apparatus according to the present invention is provided in a chamber, and a first exposure optical system for selectively irradiating a resist film made of a chemically amplified resist material with exposure light to perform pattern exposure. A system and an outgas detection means provided in the chamber and detecting the amount of outgas released from the resist film are provided.
[0014]
According to the exposure apparatus of the present invention, since the chamber provided with the first exposure optical system for performing pattern exposure is provided with outgas detection means for detecting the amount of outgas released from the resist film, Since the amount of outgas released from the exposed resist film can be easily detected, it is possible to prevent a situation in which the shape of the resist pattern is deteriorated due to the outgas released from the patterned resist film.
[0015]
The exposure apparatus according to the present invention further includes a second exposure optical system provided in the chamber and performing test exposure by irradiating the resist film with exposure light to detect an amount of outgas released from the resist film. Is preferred.
[0016]
In this way, test exposure can be performed by irradiating exposure light with a smaller exposure amount than pattern exposure for mass production, so that a large amount of outgas is released from a resist film made of a chemically amplified resist material. Even so, it is possible to prevent a situation in which the outgas adheres to the exposure optical system in the chamber and the shape of the resist pattern is deteriorated due to a decrease in the irradiation amount.
[0017]
In the exposure apparatus according to the present invention, the first exposure optical system has means for performing test exposure by irradiating the resist film with exposure light to detect an amount of outgas released from the resist film. Is preferred.
[0018]
In this way, test exposure can be performed by irradiating exposure light with a smaller exposure amount than pattern exposure for mass production, so that a large amount of outgas is released from a resist film made of a chemically amplified resist material. Even so, it is possible to prevent a situation in which the outgas adheres to the exposure optical system in the chamber and the shape of the resist pattern is deteriorated due to a decrease in the irradiation amount.
[0019]
According to the pattern forming method of the present invention, a step of forming a first resist film made of a chemically amplified resist material and a step of selectively irradiating exposure light to the first resist film in a chamber are performed. (1) the step of performing exposure, and the step of detecting the amount of outgas released from the first resist film subjected to the first exposure by outgas detection means provided in the chamber; When the amount is equal to or less than the predetermined value, while the second exposure is performed by selectively irradiating the second resist film having the same composition as the chemically amplified resist material with the exposure light in the chamber, the detection is performed. Stopping the second exposure of the second resist film when the amount of outgas exceeds the predetermined value.
[0020]
According to the pattern forming method of the present invention, when the amount of outgas detected by the outgas detecting means provided in the chamber is equal to or less than a predetermined value, exposure light is selected for the second resist film having the same composition. When the detected amount of outgas exceeds a predetermined value while performing the pattern exposure by performing selective irradiation, the outgas adheres to the exposure optical system in the chamber to stop the second exposure to the second resist film. As a result, it is possible to prevent a situation in which the shape of the resist pattern is deteriorated due to the reduction in the irradiation amount.
[0021]
In the pattern forming method according to the present invention, both the first exposure and the second exposure can be performed in an atmosphere of an inert gas.
[0022]
In this case, N ₂ gas, He gas or Ar gas can be used as the inert gas.
[0023]
In the pattern forming method according to the present invention, both the first exposure and the second exposure can be performed under a vacuum state.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an exposure apparatus according to an embodiment of the present invention will be described with reference to FIG.
[0025]
FIG. 1 shows a cross-sectional structure of an exposure apparatus according to an embodiment of the present invention, in which a base 2 provided at the bottom of a chamber 1 whose inside is kept in a vacuum state or an atmosphere of an inert gas is provided. A wafer stage 3 is provided, and a wafer 4 on which a film to be processed and a resist film are formed is held by the wafer stage 3.
[0026]
Above the wafer stage 3, a first exposure optical system 5 for pattern formation and a second exposure optical system 6 for outgas detection are provided. The first exposure optical system 5 is for performing pattern exposure by selectively irradiating, for example, extreme ultraviolet rays to a resist film formed on the wafer 4. It has a structure. On the other hand, the second exposure optical system 6 serves to locally irradiate, for example, extreme ultraviolet rays to the peripheral portion of the resist film formed on the wafer 4 to release outgas from the resist film.
[0027]
Outgas detection means 7 for detecting the amount of outgas released from the resist film is provided on the side of the chamber 1, and the outgas detection means 7 transmits the outgas from the first exposure optical system 5 to the resist film. The amount of outgas released from the resist film when irradiated with extreme ultraviolet light, or the amount of outgas released from the resist film when the resist film is irradiated with extreme ultraviolet light from the second exposure optical system 6 To detect.
[0028]
Hereinafter, a pattern forming method performed using the exposure apparatus according to one embodiment of the present invention will be described with reference to FIGS. 2 (a) to 2 (c) and 3 (a) to 3 (c).
[0029]
First, a first chemically amplified resist material having the following composition is prepared.
[0030]
Poly ((t-butyl methacrylate)-(mevalonic lactone methacrylate)) (provided that t-butyl methacrylate: mevalonic lactone methacrylate = 50 mol%: 50 mol%) (base polymer) …………………… 2g
Triphenylsulfonium triflate (acid generator) 0.08 g
Propylene glycol monomethyl ether acetate (solvent) 20 g
[0031]
Next, as shown in FIG. 2A, the first chemically amplified resist material was applied on the substrate 10 to form a first resist film 11 having a thickness of 0.2 μm. Thereafter, inside the chamber 1 in which the inside is kept in a vacuum state, as shown in FIG. 2 (b), a pole emitted from the second exposure optical system 6 is formed on the periphery of the first resist film 11. The first exposure is performed by irradiating ultraviolet rays (wavelength: 13.5 nm band) 12 with an exposure amount of 100 mJ / cm ² . By doing so, the outgas is released from the first resist film 11, so that the outgas detecting means 7 detects the amount of the outgas. In this case, since the amount of outgas detected by the outgas detecting means 7 exceeds a predetermined reference value (50 ng), the amount of outgoing light from the first exposure optical system 5 is applied to the first resist film 11. The pattern exposure is stopped without selectively irradiating ultraviolet rays.
[0032]
Then, a second chemically amplified resist material having the following composition is newly prepared.
[0033]
Poly ((2-methyl-2-adamantyl acrylate)-(mevalonic lactone methacrylate)) (however, 2-methyl-2-adamantyl acrylate: mevalonic lactone methacrylate = 50 mol%: 50 mol%) (base polymer) ............ 2g
Triphenylsulfonium nonaflate (acid generator) 0.08 g
Propylene glycol monomethyl ether acetate (solvent) 20 g
[0034]
Next, as shown in FIG. 2C, the above-mentioned second chemically amplified resist material is applied on the substrate 10 to form a second resist film 13 having a thickness of 0.2 μm. I do.
[0035]
Next, the amount of outgas released from the second resist film 13 made of the second chemically amplified resist material is predicted to be equal to or less than a predetermined reference value (50 ng). As shown in FIG. 3A, the peripheral portion is not irradiated with extreme ultraviolet rays emitted from the second exposure optical system 6 and inside the chamber 1 in which the inside is kept in a vacuum state, as shown in FIG. The resist film 13 is selectively irradiated with extreme ultraviolet rays 14 emitted from the first exposure optical system 5. Note that this exposure step is performed to detect outgassing, and thus corresponds to the first exposure.
[0036]
By doing so, the outgas is released from the second resist film 13, and the amount of the outgas is detected by the outgas detecting means 7. In this case, since the amount of outgas detected by the outgas detecting means 7 is 5 ng, which is lower than the predetermined reference value (50 ng), as shown in FIG. Heat for 60 seconds at a temperature of ° C. In this way, the acid is generated from the acid generator in the exposed portion 13a of the second resist film 13 and changes to be soluble in the alkaline developer, while the unexposed portion 13b of the second resist film 13 Since no acid is generated from the acid generator, the compound remains poorly soluble in an alkaline developer.
[0037]
Next, when the second resist film 13 is developed with a 2.38 wt% tetramethylammonium hydroxide developing solution (alkaline developing solution), an unexposed portion 13b of the second resist film 13 is formed. , A resist pattern 15 having a line width of 0.07 μm and an excellent pattern shape can be obtained.
[0038]
Since the amount of outgas released from the second resist film 13 made of the second chemically amplified resist material is equal to or less than a predetermined reference value, hereinafter, the outgas detection means 7 does not detect the outgas, After a resist film made of the second chemically amplified resist material is formed, an electrode emitted from the first exposure optical system 5 to the resist film is formed inside the chamber 1 in which the inside is kept in a vacuum state. After selectively irradiating ultraviolet rays 14, the resist film that has been subjected to pattern exposure is developed to form a resist pattern. Note that this exposure step corresponds to the second exposure because it is performed for mass production.
[0039]
According to this embodiment, only when the amount of outgas detected by the outgas detecting means 7 is equal to or smaller than a predetermined reference value, pattern exposure and development are performed to form a resist pattern. It is possible to prevent a situation in which the outgas adheres to the mirror or mask or the like and the illuminance of the exposure light is reduced, so that a resist pattern having a good cross-sectional shape can be formed.
[0040]
In the above embodiment, the chamber 1 is provided with the first exposure optical system 5 for pattern formation and the second exposure optical system 6 for outgas detection. Can be omitted. In this case, the amount of outgas emitted when the resist film is irradiated with extreme ultraviolet light emitted from the first exposure optical system 5 is detected, and the detected amount of outgas is determined by a predetermined reference value. When the value is equal to or less than the value, a resist film is formed using the same chemically amplified resist material, while when the detected amount of outgas exceeds a predetermined reference value, a resist film is formed using a different chemically amplified resist material. I do.
[0041]
In the above-described embodiment, the first exposure and the second exposure are performed inside the chamber 1 in which the inside is kept in a vacuum state. However, an inert gas such as N ₂ gas is used instead. The first and second exposures may be performed in an atmosphere of He gas or Ar gas.
[0042]
Further, in the above embodiment uses extreme ultraviolet as exposure light, there is no particular limitation on the wavelength of the exposure light, F ₂ laser light extreme ultraviolet wavelengths 1nm band ~30nm band, wavelength 157nm band, EB projection exposure or the like can be used.
[0043]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the exposure apparatus or pattern formation method which concerns on this invention, the situation where the shape of a resist pattern deteriorates due to the reduction of irradiation amount by outgas adhering to the exposure optical system in a chamber can be prevented. .
[Brief description of the drawings]
FIG. 1 is a sectional view of an exposure apparatus according to an embodiment of the present invention.
FIGS. 2A to 2C are cross-sectional views showing each step of a pattern forming method according to an embodiment of the present invention.
FIGS. 3A to 3C are cross-sectional views illustrating respective steps of a pattern forming method according to an embodiment of the present invention.
FIGS. 4A to 4D are cross-sectional views showing each step of a conventional pattern forming method.
[Explanation of symbols]
Reference Signs List 1 chamber 2 base 3 wafer stage 4 wafer 5 first exposure optical system 6 second exposure optical system 7 outgas detection means 10 substrate 11 first resist film 12 extreme ultraviolet light 13 second resist film 13a exposed portion 13b unexposed Part 14 extreme ultraviolet rays 15 resist pattern

Claims (7)

A first exposure optical system that is provided in the chamber and selectively irradiates a resist film made of a chemically amplified resist material with exposure light to perform pattern exposure;
An exposure apparatus provided in the chamber and comprising an outgas detection means for detecting an amount of outgas released from the resist film. A second exposure optical system provided in the chamber and irradiating the resist film with exposure light to perform test exposure in order to detect an amount of outgas released from the resist film. The exposure apparatus according to claim 1, wherein The first exposure optical system includes means for irradiating the resist film with exposure light to perform test exposure in order to detect an amount of outgas released from the resist film. Item 1. An exposure apparatus according to Item 1. Forming a first resist film made of a chemically amplified resist material;
Performing a first exposure by selectively irradiating the first resist film with exposure light in the chamber;
A step of detecting an amount of outgas released from the first resist film subjected to the first exposure by an outgas detection unit provided in the chamber;
When the detected amount of outgas is equal to or less than a predetermined value, the second resist film having the same composition as the chemically amplified resist material is selectively irradiated with exposure light in the chamber to form a second resist film. A step of stopping the second exposure of the second resist film when the detected amount of the outgas exceeds a predetermined value while performing the exposure. The pattern forming method according to claim 4, wherein both the first exposure and the second exposure are performed in an atmosphere of an inert gas. The inert gas, a pattern forming method according to claim 5, characterized in that the N ₂ gas, He gas or Ar gas. The pattern forming method according to claim 4, wherein both the first exposure and the second exposure are performed under a vacuum condition.

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