JP2000089475A - Exposing, coating and developing device, and resist pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the contllability of the line width of a resist pattern, to suppress occurrence of microbubbles on the interface between the resist and developer, and to decrease developing defects. SOLUTION: This device is equipped with a coating part to apply a resist on a semiconductor substrate, an irradiating part 12 of light to irradiate the resist surface with light (UV rays) to increase hydrophilicity of the resist surface, a projecting part 8 of exposure light to expose the resist through a reticle having a specified pattern as a mask to transfer the pattern of the reticle, and a developing part 11 to supply a developer to the resist to pattern the resist. By using the device, the resist surface is irradiated with light before projecting the exposure light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure coating / developing apparatus for applying a resist used in a photolithography process in the manufacture of a semiconductor device onto a wafer and patterning the resist by exposure and development, and a method of forming a resist pattern using the same. About.

[0002]

2. Description of the Related Art A conventional exposure coating / developing apparatus for forming a resist, which is used in a photolithography process in the manufacture of a semiconductor device, will be described below with reference to a schematic diagram of FIG. A resist is applied on the wafer by the exposure coating and developing apparatus shown in FIG. 4, and is patterned by exposure and development.

The indexer unit 1 includes a wafer cassette 2
The wafers 3 before and after the processing, which are loaded into the wafers 3, are stored. While the wafer 3 is loaded in the wafer cassette 2,
It is transported to the coater unit 4 and the resist is applied. The coater unit 4 is roughly classified into a spin coater and a roller coater. In many cases, a spin coater that forms a resist film by dropping a resist on a wafer 3 rotating in a horizontal state is used. The movement of the wafer cassette 2 is performed by the transfer arm 5, and the units in the exposure coating and developing apparatus are inlined.

After the application of the resist, the wafer cassette 2 is transferred to a hot plate 6 for pre-baking, and the resist is baked. The heat treatment (pre-bake) before the exposure is performed for the purpose of evaporating the residual solvent in the applied resist film and strengthening the adhesion between the resist and the wafer. Since the heat treatment is performed before exposure, the heating is performed in a temperature range in which the polymer constituting the resist is not polymerized or the additive does not thermally decompose.

[0005] The prebaking hot plate 6 is a flat metal plate subjected to a surface treatment. Generally, a heater is provided below the metal plate, and an exhaust hole is provided in a peripheral portion thereof. Alternatively, a baking device using an infrared lamp instead of a hot plate or a baking device of a hot air heating system may be provided.

[0006] A cooling plate 7 is provided alongside the pre-baking hot plate 6, and the heated wafer 3 is cooled by the cooling plate 7.
The cooling plate 7 is a flat metal plate cooled by circulation of cooling water or electronic cooling using a Peltier element.

[0007] Next, the wafer cassette 2 is
Transported to In the exposure projection device 8, exposure is performed on the wafer 3 using a reticle having a predetermined pattern as a mask, and the pattern is transferred to a resist. After the exposure, the wafer cassette 2 is transferred to the post-baking hot plate 9, where the wafer 3 is heated and the resist is cured.

The post-baking hot plate 9 is provided with a cooling plate 10 for cooling the heated wafer 3, similarly to the pre-baking hot plate 6. The cooling plate 10, like the cooling plate 7, is a flat metal plate cooled by circulation of cooling water or electronic cooling using a Peltier element.

Next, the wafer cassette 2 includes the developing unit 1
Then, the wafer 3 is immersed in an alkaline or organic solvent-based developer (dip type). Alternatively, the method of supplying the developer in the developing unit 11 may be a spin type or a spray type. When a positive resist is used, the resin in the exposed portion becomes soluble in the developer, and in the case of a negative resist, the resin in the exposed portion becomes insoluble. Thereafter, washing (spin rinsing) with pure water is performed to remove the solubilized resist.

The wafer cassette 2 is transported to the post-baking hot plate 9 again, and the wafer 3 is post-baked. Post-baking after the development is performed for the purpose of evaporating and removing the developing solution or the rinsing solution remaining on the resist, and also for hardening the resist to improve the adhesion to the wafer. The processing temperature and the processing time of the post-baking are set within a range where the formed resist pattern shape is not softened or deformed.

After the post-baking, the wafer 3 is cooled by the cooling plate 10 and the wafer cassette 2 is returned to the indexer unit 1. The above series of steps is summarized in the flowchart of FIG. As described above, application, exposure, and development of the resist are performed, and the resist is patterned.

[0012]

When a resist pattern is formed by using the above-mentioned conventional exposure coating and developing apparatus, microbubbles are generated on the resist surface in a resist development step, and defects (hereinafter referred to as development defects). Problem). Microbubbles are components that have dissolved in a resist or a developer under pressure and have been vaporized due to a change in pressure.

It is known that the frequency of occurrence of development defects depends on the wettability of the resist surface or the magnitude of the contact angle of the developer on the resist surface. 6A and 6B are cross-sectional views at the time of resist development. Resists 22 and 23 are formed on a semiconductor substrate 21, respectively, and the surface thereof is in contact with a developer 24.

As shown in FIG. 6A, when the resist 22 is hydrophilic and the contact angle α is small, microbubbles are less likely to occur and development defects are reduced. However, as shown in FIG. 6B, when the hydrophobicity of the resist 23 is high and the contact angle α ′ is large, microbubbles are easily generated, and the number of development defects increases.

FIGS. 7A and 7B are cross-sectional views showing a case where microbubbles 25 are generated during resist development. Resists 22 and 23 shown in FIGS. 7A and 7B
Are the resists 2 shown in FIGS. 6A and 6B, respectively.
2, 23. In the case of FIG. 7B in which the microbubbles 25 are easily generated, the portion where the developer 24 does not contact the resist 23 increases.

In the case shown in FIG. 7, when the developing device is changed in order to improve the developing defect of (B), for example, the developing nozzle is changed, the line width of (A) is good in the developing state. The controllability is affected, and the development defect of (A) increases. The affinity between the resist and the developing solution or the magnitude of the contact angle of the developing solution on the resist surface greatly differs depending on the combination of the resist resin and the developing solution. Therefore, it is difficult to change or replace the apparatus so as to match the hydrophilicity of the resist and the affinity between the resist and the developing solution.

Japanese Patent Application Laid-Open No. Hei 4-217258 discloses a method for improving the hydrophilicity of a resist by modifying the resist surface without changing the developing device. JP-A-4-21
According to the method for producing a resist pattern disclosed in Japanese Patent No. 7258,
After exposure of the resist, ozone generated by heating and irradiation of ultraviolet rays is reacted with the resist to impart hydrophilicity to the resist. For example, a methyl group of a resist made of a novolak resin is converted into an aldehyde by an ozone treatment to improve the hydrophilicity of the resist surface.

However, the above-mentioned Japanese Patent Application Laid-Open No. H4-2172 is disclosed.
According to the method described in JP-A-58-58, a reticle pattern is exposed and projected on a resist, and then ultraviolet irradiation is performed. Therefore, the formed resist pattern shape may be softened or deformed by the irradiation of ultraviolet light after exposure.

The present invention has been made in view of the above problems, and therefore, the present invention has high line width controllability of resist patterning and suppresses the generation of microbubbles at the interface between the resist and the developing solution. Another object of the present invention is to provide an exposure coating / developing apparatus capable of reducing development defects and a method of forming a resist pattern using the same.

[0020]

In order to achieve the above object, an exposure coating / developing apparatus according to the present invention comprises: a coating section for coating a resist on a semiconductor substrate; irradiating the resist surface with light; A light irradiating section for increasing the hydrophilicity of the resist, an exposure projecting section for exposing the resist using a reticle having a predetermined pattern as a mask, and transferring the reticle pattern to the resist, and supplying a developer to the resist. And a developing unit for patterning the resist.

The exposure coating and developing apparatus of the present invention preferably comprises
The light irradiator irradiates ultraviolet light.
Further, the exposure coating and developing apparatus of the present invention preferably has a heating means for performing a heat treatment on the resist applied on the semiconductor substrate. Further, the exposure coating and developing apparatus of the present invention is preferably characterized in that it has a heating means for performing a heat treatment on the resist exposed in the exposure projection section. The exposure coating and developing apparatus according to the present invention preferably includes a heating unit that performs a heat treatment on the resist developed in the developing unit.

This makes it possible to irradiate the resist with light, preferably ultraviolet light, before exposing and projecting the reticle pattern on the resist in the exposure coating and developing apparatus. Accordingly, it is possible to increase the hydrophilicity of the resist, increase the affinity between the resist and the developer, and reduce development defects.

Each unit in the exposure coating and developing apparatus of the present invention, that is, the coating unit, the light (ultraviolet light) irradiation unit, the exposure projection unit and the developing unit are inlined. Since the processing is performed by the automated transport means, continuous processing can be performed in the apparatus.

Further, in order to achieve the above object, a method of forming a resist pattern according to the present invention comprises the steps of: applying a resist on a semiconductor substrate; irradiating the entire surface of the resist with light; Raising the resist, exposing the resist using a reticle having a predetermined pattern as a mask, transferring the pattern of the reticle to the resist, supplying a developing solution to the resist, and developing the resist And characterized in that:

In the method for forming a resist pattern according to the present invention, preferably, the step of irradiating the entire surface of the resist with light is a step of irradiating ultraviolet light. As a result, the surface of the resist can be modified to increase the hydrophilicity, and the affinity between the resist and the developer can be increased. Therefore, in the developing step, the developing solution is uniformly diffused on the resist surface, so that development defects can be reduced.

Further, according to the resist pattern forming method of the present invention, ultraviolet irradiation is performed before exposure and projection of the reticle pattern. Therefore, unlike the case where the resist surface is modified by performing ultraviolet irradiation or the like after exposure and projection, it is possible to prevent the formed resist pattern from being damaged by the ultraviolet irradiation.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exposure coating / developing apparatus and a method for forming a resist pattern according to the present invention will be described below with reference to FIGS. FIG. 1 is a schematic diagram of an exposure coating and developing apparatus according to the present embodiment. FIG. 2 shows a flowchart of the method for forming a resist pattern according to the present embodiment.

The exposure coating / developing apparatus shown in FIG. 1 includes an indexer unit 1 like the conventional exposure coating / developing apparatus shown in FIG.
The wafers 3 before and after processing loaded in the wafer cassette 2 are stored. Wafer 3 is wafer cassette 2
Is loaded to the coater unit 4 and the resist is applied. The movement of the wafer cassette 2 is performed by the transfer arm 5, and the units in the exposure coating and developing apparatus are inlined.

After the application of the resist, the wafer cassette 2 is transported to the pre-baking hot plate 6, where the resist is baked. The heat treatment (pre-bake) before the exposure is performed for the purpose of evaporating the residual solvent in the applied resist film and strengthening the adhesion between the resist and the wafer. Since the heat treatment is performed before exposure, the heating is performed in a temperature range in which the polymer constituting the resist is not polymerized or the additive does not thermally decompose.

The pre-baking hot plate 6 is a flat metal plate that has been subjected to a surface treatment. Generally, a heater is provided below the metal plate, and an exhaust hole is provided in a peripheral portion. Alternatively, a baking device using an infrared lamp instead of a hot plate or a baking device of a hot air heating system may be provided. A cooling plate 7 is provided alongside the pre-baking hot plate 6, and the wafer 3 subjected to the heat treatment is cooled by the cooling plate 7. The cooling plate 7 is a flat metal plate cooled by circulation of cooling water or electronic cooling using a Peltier element.

Next, the wafer cassette 2 is transferred to the ultraviolet light irradiation unit 12. As a light source of the ultraviolet light irradiation unit 12, for example, a halogen lamp, a deuterium lamp, a mercury lamp, or various lasers can be used. By appropriately changing the power or time of the irradiation light, the contact angle between the resist surface and the developing solution can be reduced, and the hydrophilicity of the resist can be adjusted.

Next, the wafer cassette 2 is exposed
Transported to In the exposure projection device 8, exposure is performed on the wafer 3 using a reticle having a predetermined pattern as a mask, and the pattern is transferred to a resist. After the exposure, the wafer cassette 2 is transferred to the post-baking hot plate 9, where the wafer 3 is heated and the resist is cured.

The post-baking hot plate 9 is provided with a cooling plate 10 for cooling the heated wafer 3 similarly to the pre-baking hot plate 6. Like the cooling plate 7, the cooling plate 10 is a flat metal plate cooled by circulation of cooling water or electronic cooling using a Peltier element.

Next, the wafer cassette 2 is attached to the developing unit 1
Then, the wafer 3 is immersed in an alkaline or organic solvent-based developer (dip type). Alternatively, the method of supplying the developer in the developing unit 11 may be a spin type or a spray type. When a positive resist is used, the resin in the exposed portion becomes soluble in the developer, and in the case of a negative resist, the resin in the exposed portion becomes insoluble. Thereafter, washing (spin rinsing) with pure water is performed to remove the solubilized resist.

FIG. 3 shows an example of a sectional view of the developing step. 6A and 7A, FIG. 3A shows the case where the resist 22 has high hydrophilicity, and FIG. 3B shows the case where the resist 23 has high hydrophobicity. In the case of (B), by irradiating light of higher energy, (A) and (B)
Can be made to be substantially hydrophilic.
Therefore, good development processing can be performed on the resists 22 and 23 having different hydrophilicity without changing the developing device such as replacement of the developing nozzle.

The wafer cassette 2 is transported to the post-baking hot plate 9 again, and the wafer 3 is post-baked. Post-baking after the development is performed for the purpose of evaporating and removing the developing solution or the rinsing solution remaining on the resist, and also for hardening the resist to improve the adhesion to the wafer. The processing temperature and the processing time of the post-baking are set within a range where the formed resist pattern shape is not softened or deformed.

After the post-baking, the wafer 3 is cooled by the cooling plate 10 and the wafer cassette 2 is returned to the indexer section 1. As shown in FIG. 2, the application, exposure, and development of the resist are performed by the above-described series of steps, and the resist is patterned.

According to the exposure coating / developing apparatus and the resist pattern forming method of the embodiment of the present invention, the surface of the resist is modified to increase the hydrophilicity, and the generation of microbubbles at the interface between the resist and the developer is suppressed. Thus, development defects can be reduced. The exposure coating / developing apparatus and the resist pattern forming method of the present invention are not limited to the above embodiment. For example, after exposing the wafer 3 in the exposure projection device 8, the wafer 3 may be transported to the developing unit 11 without performing the heat treatment, and the developing process may be performed. Others
Various changes can be made without departing from the spirit of the present invention.

[0039]

According to the exposure coating and developing apparatus of the present invention, it is possible to perform light irradiation (preferably ultraviolet light irradiation) on the resist surface before exposing and projecting the reticle pattern on the resist. ADVANTAGE OF THE INVENTION According to the resist pattern forming method of this invention, it becomes possible to increase the hydrophilicity of the resist surface, suppress the generation of microbubbles at the interface between the resist and the developer, and reduce development defects.

[Brief description of the drawings]

FIG. 1 is a schematic view of an exposure coating and developing apparatus of the present invention.

FIG. 2 is a flowchart showing each step of a method for forming a resist pattern according to the present invention.

FIG. 3 is a cross-sectional view when a resist formed by using the exposure coating and developing apparatus of the present invention is developed. (A) shows a case where the hydrophilicity of the resist surface is high, and (B) shows a case where the hydrophobicity of the resist surface is high.

FIG. 4 is a schematic view of a conventional exposure coating and developing apparatus.

FIG. 5 is a flowchart showing each step of a conventional resist pattern forming method.

FIG. 6 is a cross-sectional view when a resist formed using a conventional exposure coating and developing apparatus is developed. (A) shows a case where the hydrophilicity of the resist surface is high, and (B) shows a case where the hydrophobicity of the resist surface is high.

FIG. 7 is a cross-sectional view when a resist formed using a conventional exposure coating and developing apparatus is developed. (A) shows a case where the hydrophilicity of the resist surface is high, and (B) shows a case where the hydrophobicity of the resist surface is high.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Indexer part, 2 ... Wafer cassette, 3 ... Wafer, 4 ... Coater unit (coating unit), 5 ... Transfer arm, 6 ... Pre-baking hot plate, 7, 10 ...
Cooling plate, 8: Exposure projection device, 9: Hot plate for post-baking, 11: Developing unit, 12: Ultraviolet light irradiation unit, 21: Semiconductor substrate, 22, 23: Resist, 24: Developing solution, 25: Microbubble.

Claims (7)

[Claims] 1. A coating unit for applying a resist on a semiconductor substrate, a light irradiating unit for irradiating the resist surface with light to increase the hydrophilicity of the resist surface, and a reticle having a predetermined pattern on the resist. An exposure / coating / developing apparatus comprising: an exposure / projection unit that exposes the resist to transfer the reticle pattern onto the resist; and a developing unit that supplies a developer to the resist to pattern the resist. 2. The exposure coating and developing apparatus according to claim 1, wherein said light irradiator irradiates ultraviolet light. 3. The exposure coating and developing apparatus according to claim 1, further comprising heating means for performing a heat treatment on the resist applied on the semiconductor substrate. 4. The exposure coating and developing apparatus according to claim 1, further comprising heating means for performing a heat treatment on the resist exposed in the exposure projection section. 5. The exposure coating and developing apparatus according to claim 1, further comprising heating means for performing a heat treatment on the resist developed in the developing section. 6. A step of applying a resist on a semiconductor substrate, a step of irradiating light to the entire surface of the resist to increase the hydrophilicity of the resist surface, and forming a reticle having a predetermined pattern on the resist. A resist pattern forming method, comprising: exposing as a mask to transfer the reticle pattern to the resist; and supplying a developing solution to the resist to develop the resist. 7. The method according to claim 6, wherein the step of irradiating the entire surface of the resist with light is a step of irradiating ultraviolet light.