JPH06208947A - Method and device for processing resist - Google Patents

Abstract

PURPOSE:To provide a resist processing device which can prevent any influence caused by a resist processing environment and form a proper profiling resist pattern even by using a chemical amplification resist. CONSTITUTION:A coating chamber 1a for applying a chemical amplification resist film on a substrate to be processed, a baking chamber 1b for heating a resist film, and a developing chamber 1c for developing the resist film are formed as one body, and a coater developer 1 which is constructed so as to transfer the substrates to be processed among respective chambers without exposing them to the outer air outside the device and a reduction projection aligner 2 for pattern exposure against the resist film are connected by using a gate valve. Further, a resist processing device which successively performs forming, heating, exposing, heating, and developing processes for the resist film is provided with a filter 3 consisting of a material including acidic substances in the outer air lead-in part for the coater developer 1 and the outer air lead-in part for the reduction projection aligner 2 thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing technique, and more particularly to a resist processing method and a resist processing apparatus using a chemically amplified resist.

[0002]

2. Description of the Related Art Recently, the degree of integration of semiconductor integrated circuits is 2-3.
Highly integrated at a speed of 4 times a year, the pattern dimensions of circuit elements are becoming finer year by year, and strict control of the dimensional accuracy is required. Resist (photosensitive resin) used for manufacturing semiconductor devices
For this, a phenolic resin having excellent sensitivity to exposure light and excellent dry etching resistance is used.

At present, a positive resist composed of, for example, a novolac resin and a naphthoquinonediazide compound is widely used as a resist of a phenol resin, but from the viewpoint of demand for high resolution and improvement of sensitivity, chemical amplification utilizing a catalytic reaction is performed. Expectations for resists are increasing.

When the chemically amplified resist is a positive type,
It is roughly classified into a two-component system composed of a resin and a photo-acid generator, and a three-component system in which a dissolution inhibitor is added thereto. In the two-component system, a base resin is usually used in which a phenolic resin, which is originally alkali-soluble, is blocked with hydroxyl groups by an appropriate protective group (eg ester bond) to make it alkali-insoluble.

When this type of chemically amplified resist is exposed to light, the acid generated in the exposed area attacks the ester bond in the subsequent baking step to cause the elimination reaction of the protective group, resulting in the hydroxyl group of the base resin. Occurs and the exposed area becomes alkali-soluble. Since this reaction proceeds in a chain using an acid as a catalyst, it becomes extremely sensitive. In addition, this type of resist has high light transmittance even in Deep-UV (wavelength of 300 nm or less).

However, the lithographic process using the chemically amplified resist has the following problems. As described above, the chemically amplified resist has extremely high sensitivity, but is strongly affected by the surrounding environment in the patterning step. That is, depending on the resist processing environment, the surface of the resist film becomes difficult to dissolve in the developing solution, and the shape of the resist pattern deteriorates. In an extreme case, an eaves-like sparingly soluble layer is formed on the resist pattern.

[0007] Such deterioration of the shape of the resist pattern increases the dimensional conversion difference when the underlying substrate to be processed is etched, which makes it difficult to control the pattern size with high accuracy. Furthermore, in the conventional process using the chemically amplified resist, in addition to the above-mentioned hardly soluble layer,
There arises a problem that the dimension of the resist pattern changes due to a slight change in the resist processing environment.

[0008]

As described above, in the conventional lithography process using the chemically amplified resist, the shape of the resist pattern is deteriorated due to the influence of the resist processing environment, and in extreme cases, the upper part of the resist pattern is not formed. There was a problem that an eaves-like hardly soluble layer was formed on the surface.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent adverse effects due to the resist processing environment, and to obtain a good profile even if a chemically amplified resist is used. It is to provide a resist processing method and a resist processing apparatus capable of forming a resist pattern.

[0010]

The essence of the present invention resides in the use of a filter for trapping a basic substance in order to reduce the basic substance in the resist processing environment.

That is, the present invention (Claim 1) includes a film forming step of forming a chemically amplified resist film on a substrate, a first heating step of heating the resist film formed by the step, and a heating step of the step. The exposure step of performing pattern exposure on the resist film thus exposed, the second heating step of heating the resist film exposed by the step, and the developing step of developing the resist film heated by the step are successively performed. In the resist treatment method performed as described above, at least the exposure step of the resist film and the second heating step are performed in an atmosphere passing through a filter made of a material containing an acidic substance. Here, as preferred embodiments of the present invention (Claim 1), the following are mentioned.

(1) Not only the exposure step and the second heating step that are most affected by the basic substance in the atmosphere, but all the steps are performed in an atmosphere in which the filter is made of a material containing an acidic substance. What to do

(2) Not only pass through a filter made of a material containing an acidic substance for trapping a basic substance, but also pass through a filter for removing particles in the air.

The present invention (claim 2) provides a film forming part for forming a chemically amplified resist film on a substrate, a heating part for heating the resist film, and an exposing part for performing pattern exposure on the resist film. And a developing section for developing the resist film are integrally formed, and formation of the resist film, heating, exposure, heating,
A resist processing apparatus for continuously performing a developing step is characterized in that a filter made of a material containing an acidic substance is provided in an outside air introduction part of a chamber accommodating each part. Here, as preferred embodiments of the present invention (Claim 2), the following are mentioned.

(1) Not only providing a filter made of a material containing an acidic substance for trapping a basic substance, but also providing a filter for removing particles in the air. (2) In order to avoid pressure loss due to the installation of the filter,
Provide a pressure pump at the outside air introduction part (before the filter).

[0016]

When the chemically amplified resist is used as described above, the shape of the resist pattern may deteriorate depending on the resist processing environment. As a result of diligent research conducted by the present inventors to investigate the cause, it was revealed that the main factor that deteriorates the shape of the resist pattern is a basic substance (especially ammonia in the atmosphere) present in the resist processing environment. became. That is, when a trace amount of a basic substance such as ammonia is present in the resist processing environment, the acid generated by exposure is deactivated and loses its effectiveness as a catalyst, so that the surface of the resist film becomes difficult to dissolve in a developing solution, The shape of the resist pattern deteriorates. In an extreme case, an eaves-like sparingly soluble layer is formed on the resist pattern. Further, it was also clarified that the influence of the basic substance in the resist processing atmosphere was particularly large in the resist exposure step and the heating step after exposure.

Therefore, in the present invention (Claim 1), the exposure step and the second heating step of the resist film are performed in an atmosphere which has passed through a filter made of a material containing an acidic substance. Ammonia is trapped in the filter, and as a result, it becomes possible to process the resist in an environment where the ammonia concentration is extremely low. Here, since the filter is made of a material containing an acidic substance, the basic substance can be efficiently trapped.

Further, not only the exposure step and the second heating step but also all the steps are performed in an atmosphere passing through a filter made of a material containing an acidic substance, so that the influence of the basic substance in the atmosphere is exerted. Can be reduced. Furthermore, by using a filter made of a material containing an acidic substance and a filter for removing particles in the atmosphere together, it is possible to solve the problem of dust generation from the filter made of a material containing an acidic substance.

On the other hand, according to the present invention (Claim 2), the resist is processed in an environment where the ammonia concentration is low as in the case of Claim 1 by attaching the above-mentioned filter to the outside air introduction section of the chamber accommodating each section. The atmosphere in the chamber can be collectively controlled. Further, by using a filter made of a material containing an acidic substance and a filter for removing particles in the atmosphere together, it is possible to solve the problem of dust generation from the filter made of a material containing an acidic substance.

[0020]

The details of the present invention will be described below with reference to the illustrated embodiments. <Example 1>

FIG. 1 is a diagram showing a cross-sectional structure of a resist processing apparatus according to the first embodiment of the present invention. This device
A track (coater / developer) 1 that continuously performs resist coating, baking, and development processing and a reduction projection exposure apparatus 2 that performs pattern exposure are integrated.

The coater developer 1 is composed of a coating chamber 1a for coating a resist on a substrate to be processed, a bake chamber 1b for baking the resist, and a developing chamber 1c for developing the resist, and the substrate to be processed is an apparatus between these chambers. It can be transported without exposing it to the outside air. The bake chamber 1b may be separately provided for a portion for baking the resist before exposure and a portion for baking the resist after exposure. Further, the coater developer 1 and the reduction projection exposure apparatus 2 are connected by a gate valve or the like, and the substrate to be processed can be conveyed between these without being exposed to the outside air of the apparatus.

The reduction projection exposure apparatus 2 used here
Is an excimer laser stepper using a KrF excimer laser having a wavelength of 248 nm as a light source. As shown in the figure, in this apparatus, a filter 3 made of a material in which a phosphate is impregnated based on activated carbon is attached to the upper part of the coater developer 1 and the reduction projection exposure apparatus 2. The filter 3 has a function of removing ammonia in the atmosphere introduced into the apparatus.

With such a structure, the atmosphere (clean room air) outside the apparatus (outside the chamber that shields the exposure space of the coating chamber 1a of the coater developer 1, the bake chamber 1b, the developing chamber 1c, and the exposure device 2 from the outside). 4) passes through the filter 3, traps the basic substance therein, particularly ammonia, and introduces a clean atmosphere 5 into the chamber. In this equipment, when the atmosphere outside the equipment (clean room environment) and inside was sampled and the ammonia concentration was measured by ion chromatography, respectively, the ammonia concentration outside the equipment was 8 ppb, whereas the ammonia concentration inside the equipment was Was less than 0.3 ppb. As a result, the resist processing apparatus of this embodiment cleans the resist processing environment (reduction of ammonia in the atmosphere).
It has been proved to be extremely effective for. Next, a resist processing method using the above apparatus will be described with reference to the flowchart of FIG.

First, a substrate to be treated such as Si is introduced into the coating chamber 1a of the coater developer 1, and a positive electrode containing a sulfonium salt-based photoacid generator and a poly-p-hydroxystyrene ester compound is placed on the substrate to be treated. Apply chemically amplified resist.

Next, the substrate to be processed coated with the resist is conveyed from the coating chamber 1a to the bake chamber 1b, and the processing temperature is set to 95.
Bake at 1 ° C. for 1 minute. At this time, the substrate to be processed is only transported in the coater developer 1.
It is not exposed to the outside air of the device. The baking treatment is performed to remove the solvent component from the spin-coated liquid resist.

Next, the above-mentioned baked substrate to be processed is introduced into the exposure apparatus 2, and a desired pattern is exposed at an exposure wavelength of 248 nm. At this time, acid is generated in the exposed portion of the resist. Further, since the coater developer 1 and the exposure device 2 are connected by the gate valve, the substrate to be processed is not exposed to the outside air of the device.

Next, the substrate to be processed that has been subjected to the above-mentioned exposure processing is conveyed from the exposure apparatus 2 to the baking chamber 1b, where it is baked at a processing temperature of 95 ° C. for 1 minute. By this baking treatment, the acid generated in the exposed portion of the resist attacks the ester bond to cause the elimination reaction of the protective group, and as a result, the hydroxyl group of the base resin is developed and the exposed portion becomes alkali-soluble.

Then, the above-mentioned baked substrate to be processed is conveyed from the bake chamber 1b to the developing chamber 1c and used as a developing solution.
A development process is performed using 0.14 N TMAH (tri-methyl aluminum hydroxide aqueous solution). By this development treatment, the exposed portion of the resist which has already become alkali-soluble is melted and a resist pattern is obtained.

When the positive chemically amplified resist was exposed and developed in this manner, a resist pattern having a good shape could be formed as shown in FIG. 3 (a). On the other hand, the state in which the filter 3 of the device is removed (conventional method)
When the positive chemically amplified resist was patterned in Step 2, as shown in FIG. 3 (b), an eaves-like hardly soluble layer 8 was formed on the resist pattern. From this, the effectiveness of the resist processing apparatus of the present invention was verified in an actual lithographic process using a chemically amplified resist.

In this embodiment, as the filter material attached to the upper part of the apparatus, activated carbon as a base impregnated with phosphate is used, but other than this, for example, ion exchange fiber having an acidic functional group may be used. Can be used. Further, when there is concern about dust generation from the filter material that removes ammonia in the atmosphere, a filter such as a dust filter that removes particles in the atmosphere may be used together. <Example 2>

FIG. 4 is a view showing the sectional structure of a resist processing apparatus according to the second embodiment of the present invention. Note that FIG.
The same parts as those of the above are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, a filter unit 10 in which a filter 3 composed of ion-exchange fiber having a sulfonic acid group and a dust filter 9 are integrated and a pressure pump 11 are provided outside the resist processing apparatus. The atmosphere purified by the unit 10 is sent to the inside of the apparatus by a pressure pump 11.

With such a structure, the same effect as that of the first embodiment can be obtained, and the filter 3 can be used.
The dust generated from the can be removed by the filter 9.
Further, even when pressure loss due to installation of these filters 3 and 9 is concerned, a sufficient amount of clean atmosphere can be introduced into the resist environment.

Also in the case of this example, it was confirmed that the ammonia concentration inside the apparatus was a very low value of 0.3 ppb or less. Further, when a positive chemically amplified resist containing a sulfonium acid-based photoacid generator and an ester compound of poly-p-hydroxystyrene was patterned using this apparatus, it was found to have a good shape as in the first embodiment. A resist pattern could be formed. <Example 3>

In this example, the same apparatus configuration as that shown in FIG. 4 was adopted, and ion exchange fiber having a carboxyl group was used as a filter material for removing ammonia. Even when a positive chemically amplified resist was patterned using such a resist processing apparatus, a good resist pattern could be formed as in the first embodiment.

The present invention is not limited to the above embodiments. In the examples, all steps from resist coating to development were carried out in an atmosphere passing through a filter formed of a material containing an acidic substance. Sufficient effect can be obtained even if it is performed only in the process up to the heat treatment step. Further, the apparatus configuration is not limited to that shown in FIGS. 1 and 4, and may be any configuration capable of continuously performing resist coating → first heat treatment → exposure → second heat treatment → development. In addition, various modifications can be made without departing from the scope of the present invention.

[0038]

As described in detail above, according to the present invention, in order to reduce the basic substance in the resist processing environment, by using the filter for trapping the basic substance, the basic substance in the resist processing atmosphere is reduced. The concentration of the substance can be made sufficiently low and a resist pattern having a good profile can be formed even when using a chemically amplified resist that is easily affected by the atmosphere.

[Brief description of drawings]

FIG. 1 is a diagram showing a sectional structure of a resist processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing process in the first embodiment.

FIG. 3 is a view showing a cross-sectional shape of a resist pattern formed by the present invention and a conventional resist processing method.

FIG. 4 is a diagram showing a sectional structure of a resist processing apparatus according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coater developer 2 ... Reduction projection exposure apparatus 3 ... Ammonia adsorption filter 4 ... Atmosphere before purification (clean room air) 5 ... Atmosphere after purification 6 ... Substrate 7 to be treated 7 ... Resist 8 ... Eaves-like insoluble layer 9 ... Dust Filter 10 ... Filter unit 11 ... Pressure pump 12 ... Atmosphere introduction pipe

Front page continuation (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03F 7/38 511 7124-2H 7352-4M H01L 21/30 361 H 7352-4M 361 K

Claims (2)

[Claims] 1. A film forming step of forming a chemically amplified resist film on a substrate, a first heating step of heating the resist film formed by the step, and a pattern for the resist film heated by the step. In a resist processing method, an exposure step of performing exposure, a second heating step of heating the resist film exposed by the step, and a developing step of developing the resist film heated by the step are performed in succession, A resist processing method, characterized in that at least the exposure step and the second heating step of the resist film are performed in an atmosphere which has passed through a filter made of a material containing an acidic substance. 2. A film forming portion for forming a chemically amplified resist film on a substrate, a heating portion for heating the resist film, an exposing portion for performing pattern exposure on the resist film, and developing the resist film. In a resist processing apparatus in which a developing section is integrally formed, and a resist film is formed, heated, exposed, heated, and developed in succession, a material containing an acidic substance is provided in an outside air introduction section of a chamber accommodating each section. A resist processing apparatus, which is provided with a filtered filter.