KR20070109466A - Manufacturing method of semiconductor device using immersion lithography process - Google Patents

Abstract

A method for manufacturing a semiconductor device by using an immersion lithography process is provided to prevent a photoresist pattern defect due to a water mark by performing a process for blowing an inactive gas and water cleaning to remove the water mark, before a bake process. After exposing, a water cleaning process and an inactive gas blowing process are performed to a photoresist surface, before performing a bake. A photoresist is formed on a semiconductor wafer(110). An exposure process is performed by using am immersion lithography exposure apparatus. The water cleaning and the inactive gas blowing process are performed to the surface of the photoresist. After exposing the resultant structure, a bake process is performed. The resultant structure is developed to get a required pattern.

Description

Manufacturing Method of Semiconductor Device Using Immersion Lithography Process

1A to 1E are process diagrams illustrating a method for manufacturing a semiconductor device using an immersion lithography process according to the prior art.

2 is a SEM photograph showing the number of watermark defects that occur when the immersion lithography process according to the prior art is used.

3A and 3B are schematic diagrams illustrating the generation of water droplets in an immersion lithography process according to the prior art.

4 is a schematic diagram showing a mechanism for generating defects by water droplets in an immersion lithography process according to the prior art.

5A-5D are schematic diagrams illustrating a T-top pattern formation mechanism by watermark in an immersion lithography process according to the prior art.

6A to 6F are process diagrams illustrating a method for manufacturing a semiconductor device using an immersion lithography process according to the present invention.

7 is a SEM photograph showing the number of watermark defects that occur when the immersion lithography process according to the present invention is used.

<Explanation of symbols for the main parts of the drawings>

10, 110: semiconductor wafer 12, 112: resist film

14, 114: exposure mask 16, 116: exposure lens

18, 118: water 20, 120: exposure area

22, 122: non-exposed areas 24, 124: water droplets

26: watermark 28: exposure stage

30: foreign matter 32: photoresist resin

34: dissolution inhibitor 36: photoacid generator

140: water sprayer 150: water sprayer

160: nitrogen injector

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device using an immersion lithography process. More particularly, the present invention relates to a method of manufacturing a semiconductor device by using an immersion lithography process. The present invention relates to a semiconductor device manufacturing method capable of removing a water mark.

In order to manufacture a semiconductor device which is gradually miniaturized, the size of the pattern is also gradually decreasing. In the meantime, research has been conducted toward developing an exposure apparatus and a corresponding resist in order to obtain a fine pattern.

In exposure equipment, an exposure light source is mainly a KrF of 248 nm wavelength or an ArF light source of 193 nm wavelength is applied to the production process, but gradually a short wavelength light source and a lens numerical aperture (F ₂ (157 nm) or EUV (13 nm), etc.) are applied. Efforts have been made to increase the numerical aperture.

However, when a new light source such as F ₂ is employed, a new exposure apparatus is required, which is not efficient in terms of manufacturing cost, and there is a problem that a method of increasing the numerical aperture also lowers the depth of focus.

Recently, immersion lithography processes have been developed to solve this problem. In the conventional exposure process, the exposure equipment uses air having a refractive index of 1.0 as a medium of the exposure beam between the wafer and the resist film on which the resist film is formed, whereas the immersion lithography process uses water having a refractive index of 1.0 or more as an intermediate medium (H). By using fluids such as ₂ O) or an organic solvent, the same effect as using a shorter wavelength light source or a lens having a high numerical aperture can be achieved even when using a light source of the same exposure wavelength, and there is no deterioration of the depth of focus. .

The immersion lithography process has an advantage that the depth of focus can be remarkably improved and a smaller fine pattern of less than 60 nm can be formed even using an existing exposure source.

Referring to FIG. 1A, a method of fabricating a semiconductor device using an immersion lithography process according to the related art is performed by forming a resist film 12 on an etched layer (not shown) on a semiconductor wafer 10, and then forming the resist film 12. Soft bake.

Referring to FIG. 1B, an exposure process using an exposure mask 14 and exposure equipment for immersion lithography is performed. It can be seen that water (H ₂ O) 18 is used as a medium of the exposure beam between the exposure lens 16 and the wafer 10 on which the resist film 12 is formed. At this time, components such as a photoacid generator, a quencher, and the like are released from the resist film 12 and dissolved in the water 18. The contaminated water 18 contaminates the surface of the lens 16 to improve the uniformity of the pattern line width. Lowers.

Referring to FIG. 1C, the exposure region 20 and the non-exposed region 22 are formed in the resist film 12 as a result of the exposure process, and the water droplets 24 are formed on the surface of the resist film 12.

Referring to FIG. 1D, the resultant is baked after exposure. As a result, the water droplets 24 evaporate and remain as watermarks 26. At this time, the water mark 26 consumes the acid in the exposure area 20 to prevent the dissolution inhibitor adhering to the photoresist resin from detaching during the baking process. If the desorption reaction does not occur, the exposure area 20 does not melt in the developer.

Referring to FIG. 1E, the resultant is developed to obtain a desired pattern. As a result, the defect in which the exposure area | region 20 below the water mark 26 which exists on the surface of the resist film 12 does not melt | dissolve in a developing solution, and a T-top pattern is formed.

FIG. 2 is a SEM photograph showing the number of watermark defects generated when the immersion lithography process according to the prior art is used, and the number of defects is 5000 to 10,000.

The generation of water droplets in the immersion lithography process according to the prior art will be described in more detail with reference to FIGS. 3A and 3B.

3A shows a state where the exposure stage 28 is stopped in the exposure process using the scanner type exposure equipment.

On the other hand, FIG. 3B shows the exposure stage 28 being scanned and moved to the right. As the stationary stage 28 is scanned, water droplets 24 are generated. When the stage 28 is moved to the right, the meniscus of the water 18 is bent to the left and burst. The water droplets 24 generated at this time fall onto the surface of the resist film 12.

Since the meniscus bursts faster as the scanning speed of the stage 28 increases, so much water droplet 24 also occurs. However, in the semiconductor process, even if the droplet 24 is increased, it is inevitable to increase the scanning speed of the scanner to increase productivity. Therefore, in the immersion lithography process, the development of a method capable of removing defects caused by the droplet 24 is essential.

If water droplets 24 are present on the surface of the resist film 12 as described above, water marks 26 are created during the subsequent process, and the water marks 26 make defects. Thus, defect formation by the water droplets 26 is performed. The mechanism is described with reference to FIG. 4. In FIG. 4, the top view is a plan view and the bottom view is a side view.

As the water is evaporated, the size of the water droplets 24 becomes smaller and smaller, and FIG. 4A shows an initial state in which the water droplets 24 are formed before baking after exposure and there is no foreign matter in the water droplets 24. (b) and (c) are in the post-exposure bake process. As the droplet 24 evaporates, the size thereof becomes smaller, and the foreign matter 30 gradually melts into the droplet from the surface of the resist film 12. . (d) is a state after the baking process after exposure, in which water is completely evaporated and only the foreign substance 30 left from the resist film 12 is left. The component of the foreign substance 30 varies depending on the type of photoresist, but mainly fluorine (F). ), Sulfur (S), which does not dissolve in the subsequent development process and remains as a defect.

In addition, a mechanism in which a T-top pattern is formed by a watermark in an immersion lithography process according to the prior art will be described with reference to FIGS. 5A to 5D.

FIG. 5A illustrates a state in which a resist film 12 is coated on an etched layer (not shown) on the semiconductor wafer 10 and then baked, and the resist film 12 includes a photoresist resin having a dissolution inhibitor 34 attached thereto (FIG. 32) and a photoacid generator 36.

5B is a state after exposure with an immersion lithography exposure apparatus, in which a water mark 26 is generated on the surface of the resist film 12 and the photo-acid generator 36 is emitted from the exposure region 20 of the resist film 12. Acid (H ⁺ ) is present, wherein the acid on the surface of the exposure area 20 is dissolved in the water mark 26 and disappears.

5C shows a state after the exposure bake, in which an acid serves as a catalyst to desorb the dissolution inhibitor 34 from the photoresist resin 32, in which no desorption reaction occurs because no acid is present in the exposure region 20. .

5D shows that the T-top pattern is formed, and since the desorption reaction does not occur because there is no acid in the portion where the watermark 26 is generated, it is understood that the pattern is formed in the shape of the T-top because it is not dissolved in the developer. Can be. On the other hand, the non-exposed regions 22 of the resist film 12 also do not dissolve in the developing solution such as TMAH aqueous solution because the dissolution inhibitor 34 is attached to the photoresist resin 32 without being detached.

Accordingly, the present inventors have conducted extensive research and have completed the present invention by developing a semiconductor device manufacturing method that can solve the watermark defect by an immersion lithography process that can overcome the above-mentioned problems without developing expensive equipment. It was.

The present invention has been made to solve the problem that the watermark defect phenomenon occurs in the immersion lithography process as described above, the semiconductor device manufacturing that can effectively remove the watermark generated on the surface of the resist film during the immersion lithography process It is an object to provide a method.

In order to achieve the above object, the present invention provides a method of manufacturing a semiconductor device comprising the step of washing with water and blowing an inert gas on the surface of the resist film before baking after exposure using immersion lithography.

Specifically, the semiconductor device manufacturing method according to the present invention

Forming a resist film on the etched layer on the semiconductor wafer;

Performing an exposure process using an exposure apparatus for immersion lithography;

Water washing and blowing an inert gas onto the resist film surface;

Baking the resultant after exposure; And

Developing the result to obtain a desired pattern.

The method may further perform a pre-soak process in which the surface of the resist film is treated with deionized water after the resist film formation and before the exposure process.

In addition, the process of washing the water and blowing the inert gas is performed sequentially or simultaneously, wherein the spin speed is 200 rpm, deionized water is sprayed at a rate of 25 ml / sec, and nitrogen gas is 100-1000 ml /. Spray at a speed of sec.

The water is deionized water and the inert gas is nitrogen gas (N ₂ ).

In addition, the exposure process is a light source group consisting of G-line (436nm), i-line (365nm), KrF (248nm), ArF (193nm), F ₂ (157nm) and EUV (13nm) Is selected from.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the examples are only to illustrate the invention and the present invention is not limited by the following examples.

6A to 6F are process diagrams illustrating a method of manufacturing a semiconductor device using an immersion lithography process according to the present invention.

Referring to FIG. 6A, an ArF photoresist (TOK TARF-P6111) is coated on the etched layer (not shown) on the semiconductor wafer 110 to a thickness of 0.20 μm and soft baked at 130 ° C. for 90 seconds to form a resist film 112. ). As the ArF photoresist, all kinds of immersion resists, such as TOK Corp.'s TARF-P6111 and JSR's TCX-015 and Shin-Etsu's IOC-73, can be used.

Referring to FIG. 6B, deionized water is sprayed from the water injector 140 to wash the surface of the resist film 112 for 20 seconds or more. This is a pre-soak process in which components such as a photoacid generator, quencher, etc. present on the surface of the resist film 112 are removed before exposure.

By reducing the contamination of the exposure lens by this pre-soak process, the exposure uniformity can be improved, and as a result, the uniformity of the pattern line width can be improved. In addition, reducing the contamination of the exposure lens shortens the cleaning cycle of the lens and extends the life of the lens, thereby increasing the life of the exposure equipment.

Referring to FIG. 6C, an exposure process using an exposure mask 114 and exposure equipment for immersion lithography is performed. As the light source of the exposure process, G-line (436 nm), i-line (365 nm), KrF (248 nm), ArF (193 nm), F ₂ (157 nm) or EUV (13 nm) is used. .

It can be seen that water (H ₂ O) 118 is used as a medium of the exposure beam in the middle of the wafer 110 in which the exposure lens 116 and the resist film 112 of the exposure apparatus are formed. As a result of the exposure process, the exposed region 120 and the non-exposed region 122 are formed in the resist film 112, and the water droplet 124 is formed on the surface of the resist film 112.

That is, FIG. 6C illustrates a state in which an exposure stage (not shown) is scanned and moved to the right, where water droplets 124 are generated while the stationary stage is scanned. When the stage moves to the right, the meniscus of the water 118 is bent to the left to burst, and the water droplets 124 generated at this time fall to the surface of the resist film 112.

Referring to FIG. 6D, a post-soak process of spraying deionized water from the water sprayer 150 and nitrogen gas from the nitrogen sprayer 160 on the surface of the resist film 112 is performed. At this time, the spin speed is 200 rpm, deionized water is injected at a rate of 25 ml / sec, and nitrogen gas is injected at a rate of 100 to 1000 ml / sec.

As a result of this post soak process, the water mark generated by the water droplets 124 is washed with deionized water, and the deionized water is rapidly dried by the blown nitrogen gas, whereby watermark marks appear on the surface of the resist film 112. It will not remain.

The process of washing the deionized water and blowing nitrogen gas is performed sequentially or simultaneously.

Referring to FIG. 6E, the resultant is baked at 130 ° C. for 90 seconds.

Referring to FIG. 6F, when the exposure area 120 is developed for 20 seconds or more using a TMAH 2.38 wt% aqueous solution, the non-exposure area 122 remains as a resist pattern.

FIG. 7 is an SEM photograph showing the number of watermark defects generated when the immersion lithography process according to the present invention is used. The number of defects is 50 to 100, the number of which is 1/100 compared to the conventional art. It can be seen that the decrease.

On the other hand, preferred embodiments of the present invention for the purpose of illustration, those skilled in the art will be able to various modifications, changes, substitutions and additions through the spirit and scope of the appended claims, such modifications and changes are as follows It should be regarded as belonging to the claims.

As described above, in the present invention, by performing the process of washing the water and blowing the inert gas before baking after exposure using immersion lithography, the water mark existing on the surface of the resist film is removed to effectively prevent the resist pattern defect due to the water mark. Can be prevented, and as a result, semiconductor production yield is improved.

In addition, in the present invention, the exposure uniformity may be improved by reducing the contamination of the exposure lens by performing the pre-soak process before the exposure process, and as a result, the uniformity of the pattern line width may be improved. In addition, reducing the contamination of the exposure lens shortens the cleaning cycle of the lens and extends the life of the lens, thereby increasing the life of the exposure equipment.

Claims (8)

In the semiconductor device manufacturing method using an immersion lithography process, A method of manufacturing a semiconductor device, comprising the steps of: washing water and blowing an inert gas onto the resist film surface before baking after exposure. The method of claim 1 wherein the method is Forming a resist film on the etched layer on the semiconductor wafer; Performing an exposure process using an exposure apparatus for immersion lithography; Water washing and blowing an inert gas onto the resist film surface; Baking the resultant after exposure; And Developing the resultant to obtain a desired pattern. The method according to claim 1 or 2, The method further comprises a pre-soak process for treating the surface of the resist film with deionized water after the resist film formation and before the exposure process. The method according to claim 1 or 2, The process of washing the water and blow the inert gas is a semiconductor device manufacturing method characterized in that performed sequentially or at the same time. The method according to claim 1 or 2, In the process of washing the water and blowing the inert gas, the spin speed is 200 rpm, deionized water is sprayed at a rate of 25 ml / sec, and nitrogen gas is sprayed at a rate of 100 to 1000 ml / sec. Semiconductor device manufacturing method. The method according to claim 1 or 2, The water is a semiconductor device manufacturing method characterized in that the deionized water. The method according to claim 1 or 2, The inert gas is a nitrogen gas (N ₂ ) characterized in that the semiconductor device manufacturing method. The method according to claim 1 or 2, The exposure process is carried out with a light source from the group consisting of G-line (436 nm), i-line (365 nm), KrF (248 nm), ArF (193 nm), F ₂ (157 nm) and EUV (13 nm). A method of manufacturing a semiconductor device, characterized in that performed using the selected one.

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