JPH10208997A - Method and apparatus forming pattern of resist film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a clear resist pattern if made fine by a resist pattern forming method using a chemically amplified resist for the pattern usable as an etching mask for forming a circuit pattern of a semiconductor integrated circuit device. SOLUTION: The method comprises steps of applying a chemically amplified resist contg. at least a base resist and photo-acid initiator onto a substrate 111 to form a resist film 112, exposing this film 111 to an exposure light to react this light with the photo-acid initiator in the film 112 to produce an acid therein, heating the exposed resist film 112 in a moistened atmosphere toe accelerate the solubility or cross link of the base resin with the acid and developing the resist film 112.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a resist film pattern, and more particularly, to a resist pattern used as an etching mask when forming a circuit pattern of a semiconductor integrated circuit device, and in particular, a chemically amplified resist. And a pattern forming apparatus.

In recent years, semiconductor integrated circuit devices have been required to have higher integration, and therefore, further miniaturization of circuit patterns has been required. For this reason, the exposure apparatus has been increasing the resolution and shortening the wavelength, and the resist is also required to have a higher resolution and more stable line width. Recently, highly sensitive chemically amplified resists containing a photoacid generator have been spotlighted and are being actively developed.

[0003]

2. Description of the Related Art A conventional method for forming a resist pattern using a chemically amplified resist will be described below. In order to perform a series of processes continuously, an inline system such as a pattern forming apparatus shown in FIG. 7 is employed. When forming a pattern using this in-line system, first, the substrate 101 is added to the spin coater 31 in the resist coating section.
Is placed thereon, and a resist is dropped. The spin coater 31 is rotated to apply a chemically amplified resist by a spin coating method (rotation coating method). A resist film 102 is formed on an object to be patterned on a substrate 101. At this time, the substrate 10
Since the thickness of the resist film formed is affected by the ambient temperature of the substrate 1, the temperature of the substrate 101 itself and the surrounding humidity are adjusted, and the humidity is adjusted by the temperature / humidity controller 37 as shown in FIG. The flow of the nitrogen gas or the atmospheric gas into the cup 32 also adjusts the airflow around the substrate 101 which affects the temperature distribution and the humidity distribution around the substrate 101. In the case of a ternary system, the chemically amplified resist contains a base resin, a photoacid generator, and a dissolution inhibitor in the case of a positive type.

Subsequently, the resist film 102 is heated by a first heating means 39 in order to cure the resist film 102 in a first heat treatment section. Next, in the exposure unit, the resist film 102 is exposed to exposure light via the reticle 41 or directly. In the exposed portion of the resist film 102, a reactive substance such as an acid is generated from the photoacid generator by the exposure.

Next, in a second heat treatment section, a heat treatment (PEB) after exposure is performed by a second heating means 43. Thereby, in the case of the positive chemically amplified resist, the release of the dissolution inhibiting effect of the dissolution inhibitor is promoted, and the generated acid solubilizes the base resin. At that time, the generated acid solubilizes many base resins as a catalyst in a developing solution, thereby increasing the sensitivity.

Subsequently, the resist film 1 after heating is developed in a developing section.
When immersed in the developing solution 44 and developed, the solubilized base resin is dissolved in the developing solution 44 and removed to form a pattern. In the above case, in the heat treatment after exposure, the second
A hot plate is used as the heating means 43 of FIG.
As shown in (b), a dry nitrogen gas is supplied into the chamber 42 in which the hot plate 43 is housed in consideration of the temperature distribution and the influence of sublimates from the resist film.

[0007]

In the conventional method for forming a pattern of a chemically amplified resist, the heat treatment (PEB) after exposure plays a major part in the reaction for solubilizing the base resin. High performance is required for temperature controllability, uniformity of in-plane temperature distribution, time controllability, and the like.

However, even if the hot plate 43 having high temperature controllability, uniformity of in-plane temperature distribution, and time controllability is used for the post-exposure bake (PEB), as shown in FIG. The resist pattern 102a may be distorted near the center in the thickness direction, or adjacent resist patterns 102b may be connected as shown in FIG. 9B.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has a method and an apparatus for forming a resist film capable of obtaining a sharp resist pattern even if the pattern is miniaturized. Is provided.

[0010]

SUMMARY OF THE INVENTION The first object of the present invention is to apply a chemically amplified resist containing at least a base resin and a photoacid generator onto a patterning object on a substrate. Forming a film, exposing the resist film with exposure light, reacting the exposure light with a photoacid generator in the resist film to generate an acid in the resist film, and Heating the exposed resist film in an atmosphere to promote solubilization or cross-linking of the base resin by the acid, and developing the resist film by a resist film pattern forming method. According to a second aspect of the present invention, there is provided the resist film pattern forming method according to the first aspect, wherein the humidified atmosphere is formed by passing a dried gas through water. The humidity of the humidified atmosphere is 10% or more and 80% or less, preferably 30% or more and 50% or less, which is the third invention. A fourth aspect of the present invention, which is solved by a method of forming a pattern of a resist film, is a resist coating unit, an exposure unit that exposes the resist film, a heating unit that heats the exposed resist film, and the exposed resist film. And a means for generating a gas whose humidity has been adjusted, and a means for guiding the gas whose humidity has been adjusted to the heating means.

In the pattern forming method using a chemically amplified resist, the inventor of the present invention adjusted the humidified atmosphere or humidity during the heat treatment after exposure to promote solubilization or cross-linking of the base resin by acid. It was found by experiments that the cutting of the resist pattern was improved by performing in an atmosphere, and the method was applied to the pattern forming method and the pattern forming apparatus of the present invention.

The humidified atmosphere can be obtained by blowing dry nitrogen or dry air into water, bubbling the gas, guiding the humidified gas to a heated portion of the exposed resist film, and discharging the gas. In addition, the humidity-adjusted atmosphere is obtained by, for example, branching the humidity-adjusted inert gas or atmospheric gas or the like that is led to the resist coating unit, guiding it to a heated portion of the resist film after exposure, and discharging it. .

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (1) First Embodiment FIG. 1 is a configuration diagram showing a pattern forming apparatus according to a first embodiment of the present invention. FIG. 2A is a side view showing details of a resist coating unit, and FIG. 2B is a side view showing details of a second heat treatment unit.

In the pattern forming apparatus shown in FIG. 1, an in-line system including a resist coating / developing apparatus SK-80BW (trade name) and a reduction projection exposure apparatus NSR-2005EX8A (trade name) is configured. In this case, in the resist coating / developing apparatus, the resist coating section includes a spin coater 1 for spin-coating the resist, a cup 2 for receiving unnecessary resist scattered by the rotation of the spin coater 1, and a resist discharging tool 5. is set up. As shown in FIG. 2A, a temperature and humidity controller 7 for adjusting the temperature and humidity in the cup 2 and a Introduce inert gas or atmospheric gas that generates airflow to the cup 2,
A gas pipe 6 and a gas inlet 3 to be introduced, and a flow control valve 8 for an inert gas or an atmospheric gas are provided.

The developing section is configured to be capable of spin development (paddle method) using a developing solution 24 such as TMAH (tetramethylammonium hydroxide) to develop the chemically amplified resist after exposure. Reference numeral 25 denotes a developing solution discharging tool, 26 denotes a waste liquid port, 27 denotes a spin developer, and 28 denotes a developing cup. Further, in the first heat treatment section, a first hot plate (first heating means) 9 for curing the applied chemically amplified resist film 112 by heating is provided. In the second heat treatment section,
By heating, the dissolution inhibiting effect of the dissolution inhibitor in the chemically amplified resist film 112 and the release of the crosslinking inhibiting effect of the crosslinking inhibitor are promoted, and the chemically amplified resist film 1 by the acid generated by the exposure is promoted.
A second hot plate (second heating means) 15 that promotes solubilization or cross-linking of the base material resin 12 and amplifies it is provided. The second hot plate 15 is the chamber 1
And a gas inlet 16 for introducing a humidified inert gas or the like into the chamber 14.
Is provided.

Further, as shown in FIG. 2B, a gas pipe 16 for guiding humidified inert gas or the like to the storage chamber 14 of the second hot plate 15 is provided at the gas inlet 16.
a is connected, and the other end of the gas pipe 17a is connected to a container 20 containing ultrapure water. Further, the container 20
The tip of another gas pipe 17b connected to the gas cylinder 19 is inserted into the ultrapure water 21 of FIG.
A gas flow control valve 18 is provided in the middle of the process.
The ultrapure water 21 is heated to a predetermined temperature of 20 ° C. to 70 ° C. by a hot plate (heating means) or the like. Thereby, the dry inert gas or the like guided from the gas cylinder 19 by the gas pipe 17b is blown into the ultrapure water 21 and humidified,
The humidified inert gas or the like is led to the chamber 14 through the gas pipe 17a.

In the exposure section, a reduction projection exposure apparatus is provided. A light source 11 for exposure light, an optical system 12 for narrowing the exposure light generated from the light source 11, and a mounting table 10 on which a semiconductor substrate 111 on which an object to be patterned is formed are mounted. A KrF excimer laser having a wavelength of 248 nm is used as exposure light. In addition, the numerical aperture (NA) is 0.1.
It is 50. Note that charged particles such as an electron beam (ionizing radiation) can be used as the exposure light.

Next, a method of forming a resist pattern on an object to be patterned on a semiconductor substrate using the pattern forming apparatus shown in FIGS. 1, 2A and 2B will be described with reference to FIG.
This will be described with reference to (a) to (d). FIG.
(D) is a sectional view. In addition, there are a positive type and a negative type in the chemically amplified resist, and the positive type chemically amplified resist is
Taking a ternary system as an example, it contains a base resin, a photoacid generator and a dissolution inhibitor, and a negative chemically amplified resist contains a base resin, a photoacid generator and a crosslinking inhibitor. Here, a positive resist is used as the chemically amplified resist.

First, the object to be patterned on the semiconductor substrate 111 is exposed to HMDS (hexamethyldisilazane) for processing. The HMDS process is performed to improve the adhesion between the semiconductor substrate 111 and the resist film 112. continue,
As shown in FIG. 3A, the semiconductor substrate 111 is placed on the spin coater 1 and a chemically amplified resist (TDUR-P)
009 (trade name)) is dropped, and the spin coater 1 is rotated to form a resist film 112 having a thickness of 0.78 μm on the object to be patterned. At this time, the temperature and the surrounding humidity of the semiconductor substrate 111 itself are adjusted so that a uniform resist film thickness is obtained, and an air or the like whose humidity is adjusted is flowed by an appropriate amount so that the temperature distribution and the humidity around the semiconductor substrate 111 are adjusted. Airflow adjustments that affect distribution are also made.

Next, the semiconductor substrate 111 is placed on a first hot plate (first heating means) 9 and is heated at a temperature of 90 ° C. for 90 seconds by flowing dry nitrogen to be cured. next,
As shown in FIG. 3B, a resist film 11 is formed according to a reticle 13 capable of forming a 0.35 μm line & space.
2 is exposed by exposure light. Thereby, the resist film 1
Exposure light and the photoacid generator react with each other in the exposed portion of 12, and an acid is generated from the photoacid generator. When using charged particles such as electron beams (ionizing radiation) as the exposure light,
Normally, the resist film 112 is directly scanned without passing through the reticle 13.

Subsequently, ultrapure water 2 heated to a temperature of 30 ° C.
Dry nitrogen gas having a dew point of 12 ° C. is blown into the inside 1 to perform bubbling, and the humidified nitrogen gas is introduced into the chamber 14 at a flow rate of 1 l / min. The humidity in the chamber due to the humidified nitrogen gas is about 45%. Then, as shown in FIG. 3C, the exposed resist film 112 is heated at a temperature of 100 ° C. for 90 seconds by a second hot plate (second heating means) 15 in a humidified nitrogen gas. By this heating, the dissolution inhibiting effect of the dissolution inhibitor in the chemically amplified resist film 112 is released, and the solubilization of the base resin of the chemically amplified resist film 112 by acid is promoted.

Next, the resist film 112 is developed by immersing it in a 2.38% aqueous solution of TMAH (developer) 24 for 60 seconds. As a result, as shown in FIG. 3D, the solubilized portion is dissolved, and a resist pattern 112a composed of a 0.35 μm line and space is formed. Next, the resist pattern 11 created as described above is used.
The result of observing 2c with a scanning electron microscope will be described. FIG. 4A is a cross-sectional view showing an observation result of the resist pattern 112c in the case of the first embodiment. For comparison, when promoting the solubilization of the base resin of the chemically amplified resist film 112, dry nitrogen or the like is introduced into the storage chamber 14 of the second heating means 15 without being subjected to moisture and heat-treated. FIG. 4B also shows the observation result of the resist pattern 112d.

According to the observation results, when the exposed resist film is heated in a humidified nitrogen gas,
As shown in (a), the cut of the resist pattern 112c after the development is improved. On the other hand, when heated in dry nitrogen or the like, as shown in FIG. 4B, adjacent resist patterns 112d of the developed resist pattern 112d were connected, and a good resist pattern 112d was not obtained.

It should be noted that similarly good results were obtained by using other dried inert gas or dry air instead of dry nitrogen. As described above, in the first embodiment of the present invention, since the post-exposure bake treatment that promotes the solubilization or cross-linking of the base resin by acid is performed in a humidified atmosphere, Even when the pattern is miniaturized, the cut of the resist pattern is improved.

Further, since the heating is performed in an atmosphere in which the humidity is adjusted, a sharp resist pattern can be formed with good reproducibility regardless of the humidity. This allows
The pattern of the semiconductor device can be further miniaturized, and the degree of integration can be further improved. (2) Second Embodiment FIG. 5 is a configuration diagram showing a pattern forming apparatus according to a second embodiment of the present invention.

As shown in FIG. 5, the difference from the first embodiment is that the storage chamber 14 of the second heating means 15
The humidity-adjusted air or the inert gas introduced into the cup 2 of the spin coater 1 in the resist coating unit is used as the humidity-adjusted gas to be introduced into the resist coating unit, and is branched toward the storage chamber 14 of the second heating means 15. That is, it is introduced into the storage chamber 14 of the second heating means 15. In the middle of a gas pipe 6a for guiding humidity-adjusted air or the like to the storage chamber 14 of the second heating means 15, gas flow adjusting means 8b is provided.
A gas flow control means 8a is provided in the middle of a gas pipe 6 for guiding air or an inert gas whose humidity has been adjusted to the cup 2 of the resist coating section. This is for adjusting the gas flow rate in the gas pipes 6a and 6 when one of them is stopped or the like. The other configuration of the pattern forming apparatus is similar to that of FIG.

Next, a method for forming a resist pattern on an object to be patterned on a semiconductor substrate 111 using the pattern forming apparatus according to the second embodiment will be described. A positive resist is used as the chemically amplified resist. In this case, when heating the exposed resist film 112, a resist pattern was formed by the same process and conditions as in the first embodiment except that air or the like under the following humidity conditions was introduced. Humidity adjusted to 45 ± 5
% And 35 ± 5%, resist patterns 112e and 112f were formed for each, and the shapes were observed. The observation results under each condition are shown in FIGS. 6 (a) and 6 (b), respectively.

As shown in the observation results, the observation results of the resist patterns 112e and 112f formed by the resist pattern forming method according to the second embodiment are similar to those in the first embodiment. Good resist patterns 112e and 112f were obtained. As described above, in the second embodiment of the present invention, since the post-exposure bake treatment that promotes the solubilization or cross-linking of the base resin by acid is performed in a humidity-controlled atmosphere, A sharp resist pattern can be formed with good reproducibility regardless of the humidity.

As a result, the pattern of the semiconductor device can be further miniaturized, and the degree of integration can be further improved. In the first and second embodiments, a positive type chemically amplified resist is used. However, the present invention can be applied to a negative type chemically amplified resist.

[0030]

As described above, in the present invention, the post-exposure baking is performed in a humidified atmosphere or a humidity-controlled atmosphere to promote solubilization or crosslinking of the base resin with an acid. Therefore, even when the resist pattern is miniaturized, the cut of the resist pattern is improved.

Further, by heating in an atmosphere where the humidity is adjusted, a sharp resist pattern can be formed with good reproducibility regardless of the humidity. As a result, the pattern of the semiconductor device can be further miniaturized, which can contribute to further improvement in the degree of integration.

[Brief description of the drawings]

FIG. 1 is a side view of a pattern forming apparatus according to a first embodiment of the present invention.

FIG. 2A is a side view showing details of a resist coating unit of the pattern forming apparatus according to the first embodiment of the present invention. FIG. 2B is a side view showing details of the second heat treatment section of the pattern forming apparatus according to the first embodiment of the present invention.

FIGS. 3A to 3D are cross-sectional views illustrating a pattern forming method according to the first embodiment of the present invention.

FIG. 4A is a sectional view of a resist pattern formed by the pattern forming method according to the first embodiment of the present invention. FIG. 4B is a cross-sectional view of a resist pattern formed by the pattern forming method according to the comparative example.

FIG. 5 is a side view showing a partial configuration of a pattern forming apparatus according to a second embodiment of the present invention.

FIGS. 6A and 6B are cross-sectional views of resist patterns formed under different humidity conditions by a pattern forming method according to a second embodiment of the present invention.

FIG. 7 is a side view of a pattern forming apparatus according to a conventional example.

FIG. 8A is a side view showing details of a resist coating unit of a pattern forming apparatus according to a conventional example. FIG. 8B is a side view showing details of a second heat treatment unit of the pattern forming apparatus according to the conventional example.

FIG. 9 is a cross-sectional view of a resist pattern formed by a pattern forming method according to a conventional example.

[Explanation of symbols]

 1 spin coater, 2 cups, 3,16 gas inlet, 4 exhaust port, 5 resist discharger, 6,6a, 17a, 17b gas pipe, 7 temperature and humidity controller, 8,8a, 8b, 18 gas flow control valve, Reference Signs List 9 first hot plate (first heating means), 10 mounting table, 11 light source, 12 optical system, 13 reticle, 14 chamber, 15 second hot plate (second heating means), 19 gas cylinder, 20 container , 21 ultrapure water, 22 hot plate (heating means), 24 developer, 25 developer discharging tool, 26 waste liquid outlet, 27 spin developer, 28 development cup, 111 semiconductor substrate (substrate), 112 resist film, 112a non-exposure Part, 112b exposed part, 112c-112f resist pattern.

Claims (5)

[Claims] 1. A step of applying a chemically amplified resist containing at least a base resin and a photoacid generator onto a patterning object on a substrate to form a resist film, and exposing the resist film with exposure light Reacting the exposure light with a photoacid generator in the resist film to generate an acid in the resist film; and heating the exposed resist film in a humidified atmosphere, A method for forming a resist film pattern, comprising: a step of promoting solubilization or crosslinking of the base resin by an acid; and a step of developing the resist film. 2. The method according to claim 1, wherein the humidified atmosphere is formed by passing a dried gas through water. 3. The method according to claim 1, wherein the humidity of the humidified atmosphere is 10% or more and 80% or less. 4. The method according to claim 1, wherein the humidity of the humidified atmosphere is 30% or more and 50% or less. 5. A resist coating unit, an exposure unit for exposing a resist film, a heating unit for heating the exposed resist film, a developing unit for developing the exposed resist film, and a humidity-adjusted gas. And a means for guiding the humidity-adjusted gas to the heating means.