JPH0757995A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To provide a method for forming a highly accurate resist pattern easily and stably by preventing abnormality in the profile of resist pattern in the vicinity of interface between a chemical amplification resist and a film to be micromachined. CONSTITUTION:A film to be micromachined, i.e., a carbon film 12, is formed on a silicon substrate 11 and a chemical amplifying resist film 13 is formed thereon. The resist film 13 is then exposed into a desired pattern and subjected to post exposure baking before it is developed to form a resist pattern. In such method for forming a resist pattern, the carbon film 12 is exposed to a gas containing active hydrogen under an environment containing no basic substance immediately after formation thereof and prior to formation of the resist film 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist pattern forming method in lithography, which is an important step in the manufacturing process of semiconductor devices, and more particularly to a resist pattern forming method using a chemically amplified resist.

[0002]

2. Description of the Related Art The degree of integration of a semiconductor integrated circuit is 4 in 2 to 3 years.
Although it is highly integrated at twice the speed, the pattern dimensions of circuit elements are becoming finer year by year, which requires strict control of dimensional accuracy. In the manufacture of semiconductor integrated circuits, a method of forming a fine resist pattern on a film to be processed such as a semiconductor thin film and etching the film to be processed using this pattern as a mask is adopted. This resist pattern forming step is usually performed by the following operation.

First, a solution containing a resin and a photosensitizer is applied on a film to be processed such as a semiconductor thin film and dried to form a resist film. Next, after performing an exposure process for selectively irradiating the resist film with an energy ray such as light, a mask pattern (resist pattern) is formed on the substrate by a development process. Conventionally, in forming such a pattern, a resist material using a phenolic resin, which is excellent in sensitivity to exposure light and dry etching resistance, is often used.

In order to miniaturize and improve the degree of integration of semiconductor integrated circuits, it is required to form a finer resist pattern. Therefore, ultraviolet light having a short wavelength is used as actinic radiation for pattern exposure of the resist. . When such a light source with a short wavelength is used, there is a problem that a sufficient amount of light does not reach the bottom of the resist due to attenuation of light in the resist film.

Therefore, recently, expectations for a chemically amplified resist utilizing an acid-catalyzed reaction with high dimensional accuracy and sensitivity are increasing. This chemically amplified resist material is composed of a resin containing a dissolution inhibitor and an acid generator (PA) for a positive resist.
G: Photo acid generator). When this resist is exposed, an acid is generated from PAG, this acid diffuses into the resist by post exposure bake (PEB), acts as a catalyst for the dissolution inhibitor, and dissociates it from the resin. As a result, the exposed portion becomes soluble in the developing solution and forms a positive pattern.

On the other hand, the negative resist is composed of a resin, a cross-linking agent and PAG, and the acid generated from PAG acts on the cross-linking agent as a catalyst to create active sites therein. The cross-linking of the resin progresses through the active points, and as a result, the cross-linked region becomes hardly soluble in the developing solution and thus forms a negative pattern.

Compared with the conventional non-chemical amplification type resist material having large absorption and low transparency, this chemical amplification type resist uses an acid-catalyzed reaction so that the photosensitizer can be reduced and the sensitivity is high. Since the absorption by the photosensitizer is small and the transparency is excellent, there is an advantage that the verticality of the side wall is good and it is easy to form a pattern with excellent dimensional accuracy.

However, this type of resist has the following problems. That is, the chemically amplified resist is very sensitive to the surrounding environment due to its high reactivity, and at the interface between the resist and a specific film to be processed such as a film containing BPSG, SOG, Al and carbon as one component. However, there is a problem that an abnormal resist pattern profile occurs. For example, the literature (Suga; Microelectronic Engine
ering 14 (1991) 249), it has been reported that an undercut of a pattern occurs on SOG in a chemically amplified negative resist. .

This phenomenon is presumed to be due to the following reasons. One is that the acid near the substrate interface generated by exposure is P
In the EB process, it diffuses in the film to be processed and is trapped in the film, so that the acid-catalyzed reaction in this region is inhibited. The other is that the impurities in the film diffuse in the vicinity of the substrate interface of the resist, thereby deactivating the acid generated particularly in the vicinity of the substrate interface in the exposed region of the resist.

As a result, in the positive resist, the generation of hydrophilic groups is suppressed in the exposed area, especially near the substrate interface, and the solubility in the developing solution becomes insufficient, so that FIG.
As a result, the formation of a poorly soluble layer will occur. The poorly soluble layer near the interface becomes a factor of dimensional fluctuation during etching of the film to be processed, and also becomes a major factor of deteriorating the side wall shape of the film after processing.

Further, in the case of a negative type resist, since the crosslinking reaction of the resist is suppressed, an undercut occurs in the pattern as shown in FIG. 7B, which makes it difficult to control the dimension, and in the worst case, the pattern is Falls. In FIG. 7, 1 is a substrate to be processed, 2 is a film to be processed, and 3 is a resist film.

The above-mentioned impurities in the film to be processed are contained in the clean room atmosphere such as HMDS used in the adhesion promoting process between the substrate and the resist, ammonia as a by-product thereof, and the curing agent used for the paint on the wall of the clean room. It is considered to be an inevitable basic substance. In fact, when the present inventors conducted an ion chromatography examination, it was found that about 10 times as much ammonia as the silicon substrate was adsorbed on the BPSG film. Also, BP
As a result of investigating the dependence of the film thickness of the hardly soluble layer on the amount of ammonia in the SG film, as shown in FIG. 8, there is a relationship that the less soluble layer of the resist increases as the amount of ammonia in the film increases. 1992 Autumn Society of Applied Physics, Lecture number
17pZM10 /).

This phenomenon of abnormal resist pattern is particularly remarkable on the film formed by the sputtering method and the CVD method. These films contain many active sites represented by dangling bonds in the film. It is presumed that this active site traps the acid in the exposed area or becomes an adsorption site for a large amount of basic substance. Literature (F.Ja
nsen ； J. Vac. Sci. Technol. A3, 605 (1985))
In the amorphous carbon film, the spin concentration in the film due to dangling bond is measured by the ESP method. According to this, the spin concentration in the amorphous carbon film was 10 ¹⁸ cm ^-3 . This concentration is almost the same as the concentration of acid generated in the exposed area and the concentration of adsorbed ammonia, and is sufficient to cause the above phenomenon.

Further, the chemically amplified resist is very sensitive to the surrounding environment due to its high reactivity. For example, in the process of positive resist as a reaction on the surface of the resist, the process from exposure to post exposure bake is performed. When the time is long, there is a problem that the eaves are formed in the pattern and the resolution is significantly lowered. In particular, when patterning is performed on a BPSG (boron-phosphorus silicate glass) film used as an interlayer insulating film for wiring, a poorly soluble layer for a developing solution is formed in the resist film near the interface between the substrate and the resist, There is a problem that the image quality is significantly impaired.

[0015]

As described above, in the conventional method of forming a resist pattern using a chemically amplified resist, a pattern is formed on a specific film to be processed such as a film containing carbon as a component. An abnormal pattern profile occurs near the interface between the film to be processed and the resist film due to the active sites in the film to be processed. For this reason, there is a problem that the resolution is remarkably lowered, and the dimensional controllability during processing of the film to be processed and the shape after processing are deteriorated. Further, in the patterning of the chemically amplified resist film on the BPSG film, there is a problem that a poorly soluble layer is generated in the resist film in the vicinity of the interface between the BPSG film and the resist film and the resolution is significantly lowered.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent abnormal occurrence of a resist pattern profile in the vicinity of an interface between a chemically amplified resist and a film to be processed by a simple method. It is an object of the present invention to provide a resist pattern forming method capable of stably obtaining a highly accurate pattern.

Another object of the present invention is to prevent the formation of a poorly soluble layer in the resist film in the resist film near the interface between the chemically amplified resist and the substrate to be processed, and to stably and highly accurately by a simple method. It is to provide a resist pattern forming method capable of obtaining a pattern.

[0018]

In order to solve the above problems, the present invention employs the following configurations. That is, according to the present invention (Claim 1), after forming a film to be processed on a substrate to be processed, a resist film is formed on the film to be processed, and then the resist film is pattern-exposed to a desired pattern, and then the resist film is formed. In a method of forming a resist pattern in which a heat treatment is performed and then a resist film is developed, the processed film is exposed to a gas containing active hydrogen immediately after the processed film is formed and before the chemically amplified resist film is formed. It is characterized by exposing. At this time, it is preferable to expose to a gas containing active hydrogen in an environment containing no basic substance.

Here, the gas containing active hydrogen is a gas used for binding to an active site represented by a dangling bond in the film to be processed and deactivating it.
Specifically, it refers to hydrogen plasma, radicals, and excited molecules. In addition to this, hydrogen gas activated by UV light, heat, etc. is also included in this.

Various methods can be used as a means for generating a gas containing active hydrogen. Specifically, a method of generating active species such as hydrogen plasma, radicals and excited molecules by an electric field or a magnetic field, or UV light,
There is a method of activating gas molecules of hydrogen by heat. Any material that can introduce hydrogen into the film to be processed may be used. As the plasma treatment, a method in which a discharge part is provided in a reaction vessel and hydrogen gas introduced into the reaction vessel is converted into plasma, and a chemical dry etching (CDE) method is used, is performed by microwaves outside the reaction vessel. There is a method of drawing the generated plasma into the container.

In the latter method, the discharge region and the reaction region are physically separated, and there is no impact on the substrate to be processed due to radiation, ions, etc. Therefore, damage to the substrate to be processed can be reduced. In addition to this, a method of introducing hydrogen gas into a reaction vessel in a vacuum state and irradiating the gas with UV light to bring these gases into an excited state and introducing the generated active species into the film to be processed. The same effect can be obtained by further heating the gas in the reaction vessel and activating it with heat energy.

In the present invention, as an environment for carrying out the above means, an environment not containing a basic substance is realized. As a concrete method therefor, a method of making the inside of the reaction vessel into a vacuum state, or argon or There is a method of purging with an inert gas such as helium. However, the basic substance referred to here is a substance which directly causes the pattern abnormality of the resist, or a basic substance which indirectly causes the pattern abnormality of the resist as a decomposition product. , Does not include substances that do not participate in pattern abnormalities, such as certain quaternary amines.

Further, the treatment in the gas containing active hydrogen is carried out within 2 hours after the formation of the film to be processed in order to minimize the contamination from the basic substance in the atmosphere. In this case, the assumed concentration of the basic substance in the atmosphere is 10 ppb. Therefore, in an atmosphere of a basic substance with a lower concentration, the degree of contamination of the film to be processed by the basic substance in the atmosphere becomes small, so that the time from the formation of the film to the processing can be made longer. Is. Before performing the above treatment, the basic substance adsorbed in the film to be processed is removed by a method of heating the substrate or a method of washing with pure water or an aqueous solution having an effect of removing the basic substance. This is not the case.

Further, when there is a basic substance remaining in the film to be processed during the above treatment, the basic substance desorbed from the film to be processed due to temperature rise or ion bombardment is always kept in the reaction vessel. It is desirable to use a treatment method that also has an effect of removing such a material by exhausting it.

Further, according to the present invention (claim 2), a resist film containing a second compound which forms a film to be processed on a substrate to be processed and then generates an acid on the film to be processed by irradiation with actinic radiation. In the method for forming a resist pattern in which a resist film is formed, and then the resist film is exposed to a desired pattern, the resist film is heat-treated, and then the resist film is developed. It is characterized in that a first compound that generates an acid upon irradiation with actinic radiation is brought into contact with it.

Here, the second compound that generates an acid upon irradiation with actinic radiation is not particularly limited, and various known compounds and mixtures can be used. Also,
As a means for bringing the first compound into contact with the surface of the film to be processed, a solution containing the first compound may be brought into contact with the surface of the film to be processed. The solvent that dissolves the first compound may be any solvent that can dissolve the compound, and for example, organic solvents such as ethyl cellosolve acetate, ethyl lactate, propylene glycol monomethyl ether acetate, and methyl methoxypropionate can be used.

According to the present invention (claim 3), a chemically amplified resist film is formed on a film to be processed formed on a substrate to be processed, a desired pattern is exposed on the resist film, and then the resist film is formed. In the resist pattern forming method of developing the resist film after the heat treatment, the adhesion promoting treatment is performed on the surface of the film to be processed before the resist film is formed, and the film to be processed is further heat treated. There is.

Here, the adhesion promoting treatment is a treatment for making the surface of the film to be processed hydrophobic, and the treating agent used therefor is, for example, HMDS capable of introducing a trimethylsilyl group, but is not limited thereto. As the heat treatment performed between the adhesion promoting treatment and the resist film forming step, the substrate to be treated is heated to 100 ° C. or higher. Further, the leaving time from the heating of the substrate to be coated with the resist is set to 10 minutes or less, or the substrate to be processed is placed in an atmosphere purged with an inert gas during the leaving. .

[0029]

According to the present invention (Claim 1), the basic substance existing in the atmosphere immediately after the film to be processed is formed on the substrate to be processed is adsorbed to the film to be processed as much as causing the abnormal pattern. Previously, by exposing the film to be processed to a gas containing active hydrogen, preferably in an environment not containing a basic substance, a base to an active site represented by dangling bonds, which is often present in the film to be processed, is present. While suppressing the adsorption of volatile substances,
It can be deactivated by blocking this active site with hydrogen.

By the above method, since the diffusion of acid into the film or the adsorption of basic substances can be suppressed, the formation of the hardly soluble layer or the undercut in the vicinity of the interface with the film to be processed in the chemically amplified resist. Occurrence can be suppressed.
That is, dimensional controllability is good even when the film to be processed is etched, and a good pattern shape can be obtained.

Further, according to the present invention (claim 2), the first compound capable of generating an acid upon irradiation with actinic radiation can be made to exist at a high concentration in the vicinity of the interface between the substrate and the resist film. That is, prior to the application of the resist solution, a solution containing the first compound that generates an acid upon irradiation with actinic radiation is brought into contact with the substrate to be processed, and then ordinary resist application and post-application baking are performed to form a resist film. Thereby, the acid generator having a higher concentration than that in the resist film can be present near the interface between the resist film and the substrate.

By performing normal pattern exposure after forming the resist film by this method, the acid generator existing in the resist film and at the resist-substrate interface is decomposed to generate protons. Since the acid generator in the vicinity of the interface has a higher concentration than that in the resist film, the acid concentration in the resist film before development should compensate for the effect that the proton concentration sharply decreases near the interface with the substrate. As a result, it becomes possible to avoid an abnormality in the resist profile.

Further, according to the method of the present invention, since the same solvent as that used for the resist can be used as the solvent of the acid generator solution, the treatment is carried out in the coater-developer apparatus used for resist coating. It can be carried out. Therefore, the resist can be applied almost in no time after the treatment, and it is possible to prevent the substrate to be processed from re-adsorbing the basic substance from the atmosphere in the clean room.

According to the present invention (Claim 3), a resist film is formed on the substrate to be treated which has been subjected to the adhesion promoting treatment and the subsequent heat treatment, thereby eliminating hydroxyl groups on the surface of the substrate to be treated, Since the surface can be replaced with a hydrophobic group such as trimethylsilyl group, the influence on the chemically amplified resist of the substrate to be processed is suppressed, and it becomes insoluble in the developing solution in the resist film near the interface between the resist film and the substrate to be processed. Generation of layers can be suppressed, and dimensional variation of the pattern can be further reduced. Furthermore, by heating the substrate to be processed after performing the adhesion promoting process, the basic substance generated as a by-product in the adhesion promoting process can be desorbed. Moreover, by keeping the heating temperature below the decomposition temperature of the hydrophobic group on the surface, peeling of the resist during development can be prevented.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view showing a resist pattern forming process according to a first embodiment of the present invention.

First, as shown in FIG. 1A, a carbon film (processed film) 12 having a film thickness of 0.1 μm was formed on the surface of a silicon substrate (processed substrate) 11 by magnetron sputtering. The carbon film 12 is used as an antireflection film on the highly reflective substrate.

Next, as shown in FIG. 2A, the substrate 10 to be processed having the carbon film 12 formed on the silicon substrate 11 is placed in the reaction vessel 20. Parallel plate electrodes 21 and 22 are installed in the reaction container 20, and the substrate to be processed 1
0 is placed on the lower electrode 22. The inside of the reaction vessel 20 was evacuated to 100 mToor in advance, and hydrogen gas was introduced from the gas introduction port at a flow rate of 100 sccm to form parallel plate electrodes 21 and 2.
Between the two, the microwave power supply 23 applied a microwave having a frequency of 2.45 GHz at 1 kW for 5 minutes.

At this time, the period from the formation of the carbon film 12 as the film to be processed to the plasma treatment was 30 minutes. Further, the ammonia concentration in the atmosphere at this time is 10
It was ppb.

Then, as shown in FIG. 1 (b), a part of poly (p-vinylphenol) is t-coated on the carbon film 12.
A solution of a chemically amplified positive resist containing a polymer blocked with ert-butoxycarbonylmethyl group and triphenylsulfonium triflate is applied, and then a pre-exposure bake is performed on a hot plate at 90 ° C. for 90 seconds to obtain a thick film. A resist film 13 having a thickness of 1.0 μm was formed.

Then, as shown in FIG. 1C, a reduction projection exposure apparatus using an excimer laser beam (wavelength: 248.4 nm) using a mixed gas of krypton, fluorine, and helium was used to expose the carbon film 12. Mask 1 on resist film 13
Exposure light 15 is radiated via 4 to perform pattern exposure,
The exposed area 16 was formed. At this time, the energy intensity is 3
It was 0 mJ / cm ² .

Then, as shown in FIG. 1D, post exposure bake was performed on the hot plate 17 at 90 ° C. for 90 seconds, and after the post exposure bake was completed, the sample was cooled to 23 ° C. Thereafter, as shown in FIG. 1 (e), the film was immersed in a 2.38 wt% tetramethylammonium hydroxide (TMAH) aqueous solution for 90 seconds for development processing.

As a result of observing the pattern thus obtained with a scanning electron microscope (SEM), a line width of 0.
At 3 μm, a pattern with a good profile with vertical sidewall angles was obtained.

Thus, according to this embodiment, immediately after the carbon film 12 is formed, the substrate 10 to be processed is housed in the reaction container 20 and exposed to hydrogen plasma, so that the basic substance is adsorbed to the active sites. While suppressing, this active site can be blocked and deactivated with hydrogen. Therefore, it is possible to suppress the diffusion of the acid into the carbon film 12 or the adsorption of the basic substance, so that the formation of the hardly soluble layer or the undercut in the vicinity of the interface with the carbon film 12 in the chemically amplified resist 13 can be suppressed. It becomes possible. Therefore, it is possible to prevent abnormal occurrence of the resist pattern profile and obtain a highly accurate pattern. (Embodiment 2) This embodiment is basically the same as the first embodiment, and is different from the first embodiment in the processing method before resist formation. First, similarly to the first embodiment, a carbon film 12 having a film thickness of 0.1 μm was formed on the surface of the silicon substrate 11 by the magnetron sputtering method.

Next, as shown in FIG. 2B, the substrate 10 to be processed is evacuated to 100 mToor in advance, and the reaction container 24 is evacuated.
Placed inside. After that, hydrogen gas is introduced into the microwave discharge tube 25 installed outside the reaction container 24 at a flow rate of 500 sccm, and the activated hydrogen gas is introduced into the reaction container 24, whereby the carbon film 12 as a film to be processed is introduced. Hydrogen was introduced. The conditions for microwave discharge were a frequency of 2.45 GHz and a power of 1 kW.

At this time, the period from the formation of the carbon film 12 as the film to be processed to the above plasma treatment was 30 minutes. Further, the ammonia concentration in the atmosphere at this time is 10
It was ppb.

After this, in the same way as the first embodiment,
Formation of the chemically amplified positive resist film 13, exposure of a desired pattern, post exposure bake, and development processing were performed. As a result, similar to the first embodiment, the line width is 0.3 μm.
A good profile pattern was obtained with a vertical sidewall angle at m. (Embodiment 3) This embodiment is basically the same as the first embodiment, and is different from the first embodiment in the processing method before resist formation. First, a carbon film having a thickness of 0.1 μm was formed on the surface of a silicon substrate by a magnetron sputtering method.

Next, as shown in FIG. 3A, the substrate 10 to be processed is evacuated to 100 mTorr in advance, and the reaction container 26 is evacuated.
Placed inside. Then, hydrogen gas was introduced into the reaction vessel 26 at a flow rate of 500 sccm. The reaction container 26 can irradiate the UV light from the xenon-mercury lamp to the gas in the reaction container 26 from the upper part of the container through the quartz plate 27. Next, the introduced hydrogen gas was activated by UV irradiation to introduce hydrogen into the carbon film 12 as the film to be processed.

At this time, the time from the formation of the carbon film 12 as the film to be processed to the light irradiation treatment was set to 30 minutes.
Also, the ammonia concentration in the atmosphere at this time is 10 ppb.
Met.

From this point onward, as in the first embodiment,
Formation of the chemically amplified positive resist film 13, exposure of a desired pattern, post exposure bake, and development processing were performed. As a result, similar to the first embodiment, the line width is 0.3 μm.
A good profile pattern was obtained with a vertical sidewall angle at m.

Incidentally, in a reaction vessel into which hydrogen gas was introduced,
Similar results were obtained by introducing a mixed gas of hydrogen and argon or helium for pressure adjustment. (Embodiment 4) This embodiment is basically the same as the first embodiment, and is different from the first embodiment in the processing method before resist formation. First, similarly to the first embodiment, a carbon film 12 having a film thickness of 0.1 μm was formed on the surface of the silicon substrate 11 by the magnetron sputtering method.

Next, as shown in FIG. 3B, the substrate 10 to be processed was placed in the quartz reaction container 28 that had been evacuated to 100 mToor in advance. Then, hydrogen gas was introduced into the reaction vessel 28 at a flow rate of 500 sccm. A heating wire 29 is arranged around the reaction container 28 so that the gas and the substrate in the reaction container 28 can be heated. A thermocouple 30 is arranged on the substrate so that the temperature of the substrate can be confirmed. Next, hydrogen gas was introduced, and the temperature of the substrate was set to 200 ° C.
After heating for 0 minute, hydrogen was introduced into the carbon film 12 as the film to be processed.

At this time, it took 30 minutes from the formation of the carbon film 12 as the film to be processed to the above heat treatment.
Also, the ammonia concentration in the atmosphere at this time is 10 ppb.
Met.

After this, in the same manner as in the first embodiment,
Formation of the chemically amplified positive resist film 13, exposure of a desired pattern, post exposure bake, and development processing were performed. As a result, similar to the first embodiment, the line width is 0.3 μm.
A good profile pattern was obtained with a vertical sidewall angle at m.

In this case as well, similar results were obtained by introducing a mixed gas of hydrogen and argon or helium into the reaction vessel into which hydrogen gas had been introduced in order to adjust the pressure.
In order to verify the effect of the present invention, the present invention was applied to the substrate to be processed on which the film to be processed was previously exposed to a basic atmosphere. First, a carbon film 12 having a film thickness of 0.1 μm is formed on the surface of a silicon substrate 11 by magnetron sputtering in the same manner as in the first embodiment.
0 was left in an atmosphere of 10 ppb ammonia for 3 days.
After that, the substrate 10 to be processed was washed with pure water at room temperature for 10 minutes and dried by a spin dry method.

Then, as in the first embodiment, the substrate 10 to be processed is evacuated to 100 mToor in the reaction chamber 20.
And a hydrogen gas was introduced at a flow rate of 100 sccm, and a microwave having a frequency of 2.45 GHz was applied to the parallel plate electrodes 21 and 22 at 1 kW for 5 minutes. The period from the pure water cleaning to the plasma treatment was 10 minutes.

After this, similarly to the first embodiment,
Formation of the chemically amplified positive resist film 13, exposure of a desired pattern, post exposure bake, and development processing were performed. As a result, similar to the first embodiment, the line width is 0.3 μm.
A good profile pattern was obtained with a vertical sidewall angle at m.

Similarly, in order to verify the effect of the present invention,
The present invention was applied to a substrate to be processed on which a film to be processed was previously exposed to a basic atmosphere. First, similarly to the first embodiment, a carbon film 12 having a film thickness of 0.1 μm is formed on the surface of a silicon substrate 11 by a magnetron sputtering method, and the substrate 10 to be processed is placed in an ammonia atmosphere of 10 ppb for 3 days. I left it. Then, the substrate 10 to be processed is
Heat at 00 ° C for 10 minutes, leave on cooling plate for 30 seconds,
Cooled to room temperature.

Then, as in the first embodiment, the substrate 10 to be processed is placed in the reaction vessel 20 which has been evacuated to 100 mToor in advance, hydrogen gas is introduced at a flow rate of 100 sccm, and the parallel plate electrodes 21 and 22 are subjected to frequency. A microwave of 2.45 GHz was applied at 1 kW for 5 minutes. The period from the pure water cleaning to the plasma treatment was 10 minutes.

After this, similarly to the first embodiment,
Formation of the chemically amplified positive resist film 13, exposure of a desired pattern, post exposure bake, and development processing were performed. As a result, similar to the first embodiment, the line width is 0.3 μm.
A good profile pattern was obtained with a vertical sidewall angle at m.

When the carbon film was not subjected to the treatments of Examples 1 to 4 and the same treatments as those of the Example were carried out except this step, the obtained pattern was as shown in FIG. 7 (a). As shown, a 0.1 μm-thick undeveloped layer was formed in the resist film in the vicinity of the interface between the film to be processed containing carbon as one component and the resist film as shown in FIG.

Although carbon is used as the film to be processed in the first to fourth embodiments, it can be applied to various conductive films other than carbon, and further to an insulating film. . Also, active hydrogen was used as a treatment for deactivating the active sites in the film to be processed, but other elements other than hydrogen can be used as long as they do not adversely affect the film to be processed. Is. (Embodiment 5) FIG. 4 is a sectional view showing a resist pattern forming step according to a fifth embodiment of the present invention. In this example, an acid generator having a higher concentration than that of the resist film is present at the interface between the resist film and the film to be processed.

First, as shown in FIG. 4A, a carbon film 42 was deposited on a bare silicon substrate 41 by a DC sputtering method so as to have a film thickness of 100 nm. Then
As shown in FIG. 4 (b), a solution 44 in which triphenylsulfonium trifluoromethanesulfonic acid was dissolved as a first acid generator 43 in ethyl cellosolve acetate to a concentration of 1% was placed on the substrate. The acid generator solution 44 was applied to the entire surface of the substrate by pouring the solution and rotating the substrate at 500 rpm, and then the substrate was rotated at 5000 rpm to volatilize the solvent.

Next, as shown in FIG. 4 (c), a positive chemically amplified resist 46 composed of the second acid generator 45, polyvinylphenol and ethyl cellosolve acetate is applied in a thickness of 1 μm, and then hot at 95 ° C. for 90 seconds. The solvent in the resist 46 is removed by heating on the plate.

The acid generator 45 contained in the resist 46 may be the same as or different from the one contained in the acid generator solution 44 of FIG. 4B. Next, as shown in FIG. 4D, KrF excimer light is pattern-exposed through a photomask 47, and then 95
The photosensitive reaction was allowed to proceed by baking after exposure at 90 ° C. for 90 seconds. After that, alkali development was performed for 90 seconds with a tetramethylammonium hydroxide aqueous solution to form a resist pattern 49 as shown in FIG.

As a result of observing a cross section of the resist pattern thus formed by SEM, it was confirmed that a good resist profile was formed in which the cross section was vertical and there was no residual resist at the bottom.

Although triphenylsulfonium trifluoromethanesulfonic acid was used as the acid generator in this embodiment, any substance can be used as long as it can generate an acid upon irradiation with actinic radiation used for exposure. For example, diazonium salts, phosphonium salts, sulfonium salts, iodonium salts _{CF 3 SO 3, p-CH} 3 PhSO 3 -, p-
A salt such as NO ₂ PhSO ₃ ⁻ , an organic halogen compound, orthoquinone-diazide sulfonium chloride or the like can be used.

Further, the method of bringing the acid generator solution into contact with the substrate is not limited to the method of this embodiment. For example, the substrate before resist film formation may be dipped in the acid generator solution for a certain period of time, or may be atomized and sprayed on the surface of the layer to be processed. Further, in order to sufficiently permeate the acid generator into the layer to be processed, the acid generator solution may be kept stationary in contact with the layer to be processed, or the substrate may be heated in that state.

Although KrF excimer light is used as the exposure light in this embodiment, various exposure wavelengths can be used without being limited to this. Further, the first acid generator contained in the acid generator solution that is brought into contact with the substrate before the resist coating need not be the same as the second acid generator contained in the resist. The generator and the second acid generator are selected such that they decompose at different wavelengths to generate an acid, and the exposure light at the time of pattern exposure before or after the pattern exposure for decomposing the second acid generator. The first acid may be decomposed by exposing the entire surface with light having a different wavelength. (Embodiment 6) FIG. 5 is a sectional view showing a resist pattern forming process according to a sixth embodiment of the present invention. In this embodiment, an adhesion promoting process is performed on the substrate surface before resist formation.

First, as shown in FIG. 5A, atmospheric pressure C is applied to the surface of the silicon substrate 51 formed in a predetermined element region.
A BPSG film 52 having a thickness of 0.8 μm was formed by the VD method. Next, after performing adhesion promoting treatment on the surface of the substrate, the substrate was heated at 100 ° C. for 30 minutes on the hot plate 53 as shown in FIG. 5B.

Here, the adhesion promoting treatment was performed as follows. The substrate is loaded into a closed chamber equipped with a hot plate and a HMDS supply device. The substrate is heated to 100 ° C. On the other hand, nitrogen is bubbled through the HMDS, and the nitrogen containing the HMDS is introduced into the chamber. The processing time of the substrate is 60 seconds. The substrate heating temperature and processing time may be set so that the resist does not peel off during development and the resist does not splash on the substrate during resist application.

The effect of the HMDS treatment on the profile abnormality of the chemically amplified resist is considered as follows. It is considered that ammonia in the substrate, which is mentioned as the cause of the profile abnormality at the resist substrate interface of the chemically amplified resist, is taken into the substrate together with water. It is believed that this water exists in the substrate around the polar groups such as OH groups via hydrogen bonds. Therefore, by blocking the OH group with a hydrophobic substituent with a silane coupling agent such as HMDS, adsorption of water is prevented, which in turn prevents adsorption of ammonia.

Further, by heating the substrate which has been subjected to this treatment, ammonia remaining in the substrate is removed, and since the surface is hydrophobic, re-adsorption of water can be prevented.

When HMDS is used as the treating agent, NH ₃ is generated as a by-product, and it is considered that this NH ₃ is also desorbed by the heat treatment after the treatment. H as a treatment
In addition to MDS, any substance that can introduce a trimethylsilyl group onto the surface of the substrate can be used.

Next, as shown in FIG. 5D, a chemically amplified negative resist was spin-coated on this substrate. The standing time from substrate heating to resist film formation is 10 minutes. Then, the resist is pre-exposure baked on a hot plate at 125 ° C. for 90 seconds to give a thickness of 1.0 μm.
The resist film 54 of was formed.

Then, similarly to the first embodiment, pattern exposure is performed by a reduction projection exposure apparatus using an excimer laser, and then post exposure bake is performed,
Further, it was developed with an aqueous TMAH solution.

As a result, a pattern having a good profile with vertical side wall angles as shown in FIG. 6A was obtained. The heat treatment of the BPSG film after the adhesion promoting treatment was not carried out, and the same treatment as in the sixth embodiment was carried out except this step. The obtained pattern had a sidewall angle as shown in FIG. 6 (b). A small undeveloped layer having a thickness of 0.1 μm was formed in the resist film 54 near the interface between the BPSG film 52 and the resist film 54. (Embodiment 7) This embodiment is basically the same as the sixth embodiment. The difference from the sixth embodiment is that the substrate is placed in an inert gas after the heat treatment after the adhesion promoting treatment. I have to leave it. That is, if there is a waiting time after the above heat treatment until the next processing is started, the substrate is not left in the atmosphere but is left in an inert substrate.

First, as in the sixth embodiment, FIG.
As shown in (b), the BPSG film 52 having a thickness of 0.8 μm was formed on the surface of the silicon substrate 51 by the atmospheric pressure CVD method, and then the adhesion promoting process was performed. Then, the substrate was heated at 100 ° C. for 30 minutes. Next, as shown in FIG. 5C, the substrate was placed in a container 55 and left in an inert gas for 1 hour, and then a chemically amplified negative resist was spin-coated on the substrate. The standing time from the end of standing in the inert substrate to the formation of the resist film is 10 minutes.

Next, as shown in FIG. 5 (d), the resist film was pre-exposure baked on a hot plate at 125 ° C. for 90 seconds to form a resist film having a thickness of 1.0 μm.
Then, similarly to the first embodiment, pattern exposure is performed by a reduction projection exposure apparatus using an excimer laser, post exposure bake is performed, and then TM exposure is performed.
It was developed with an AH aqueous solution.

As a result, a pattern having a good profile with vertical side wall angles as shown in FIG. 6A was obtained. After the BPSG film was heat-treated, it was left in the atmosphere for 1 hour without being left in the inert gas, and otherwise the same treatment as in the seventh embodiment was performed, and the obtained pattern was as shown in FIG. As shown in (b), the sidewall angle is small, and the thickness of the resist film near the interface between the BPSG film and the resist film is 0.1 μm.
m of undeveloped layer had been formed.

[0080]

As described above, the present invention (Claim 1).
According to the method, immediately after forming the film to be processed on the substrate to be processed,
By exposing to a gas containing active hydrogen in an environment containing no basic substance, it is possible to suppress the influence of the film to be processed on the chemically amplified resist, and to obtain a pattern with a good profile using the resist. it can.

According to the present invention (Claim 2), the presence of the acid generator having a higher concentration than that of the resist at the interface between the resist and the film to be processed causes chemical amplification that is easily influenced by the underlying substrate. Even when a resist is used, a resist pattern having a good profile can be formed, and the problems such as the deterioration of the shape of the bottom of the resist pattern and the formation of the hardly soluble layer, which are found in the conventional method, can be solved.

According to the present invention (Claim 3), heat treatment is performed after the adhesion promoting treatment on the substrate to be treated, and the substrate leaving time after the heat treatment until the resist film forming step is within 10 minutes. By doing so, the influence from the substrate to be processed can be reduced, and a pattern with a good profile can be obtained using the chemically amplified resist. Also, the same effect can be obtained by placing the substrate to be processed in an inert gas from the heat treatment to the resist film forming step.

[Brief description of drawings]

FIG. 1 is a sectional view showing a resist pattern forming process according to a first embodiment.

FIG. 2 is a diagram showing an example of a processing apparatus used in the first and second embodiments.

FIG. 3 is a diagram showing an example of a processing apparatus used in third and fourth embodiments.

FIG. 4 is a sectional view showing a resist pattern forming step according to a fifth embodiment.

FIG. 5 is a sectional view showing a resist pattern forming step according to sixth and seventh embodiments.

FIG. 6 is a cross-sectional view showing profiles of resist patterns according to sixth and seventh embodiments in comparison with a conventional example.

FIG. 7 is a cross-sectional view for explaining problems when a chemically amplified resist is used.

FIG. 8 is a characteristic diagram showing the relationship between the amount of ammonia and the film thickness of the hardly soluble layer.

[Explanation of symbols]

11, 41, 51 ... Silicon substrate 12, 42 ... Carbon film (working film) 13, 46, 54 ... Resist film 14, 47 ... Mask 15 ... Exposure light 16 ... Exposure area 17 ... Hot plate 20, 24, 2
6, 28 ... Reaction vessels 21, 22 ... Parallel plate electrodes 25 ... Microwave discharge tube 27 ... Quartz plate 29 ... Heat wire 30 ... Thermocouple 43 ... First acid generator 44 ... Acid generator solution 45 ... Second acid Generating agent 49 ... Resist pattern 52 ... BPSG film (work film) 53 ... Hot plate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location G03F 7/039 7/38 501 7124-2H 7352-4M H01L 21/30 571 (72) Inventor Tamaki Makiko 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Within the Toshiba Research and Development Center, a stock company (72) Inventor, Kiyoko Takase 25-1 Ekimaehonmachi, Kawasaki-ku, Kawasaki-shi, Kanagawa 1 Toshiba Microelectronics Co., Ltd.

Claims (3)

[Claims] 1. A film to be processed is formed on a substrate to be processed,
Exposing the film to be processed to a gas containing active hydrogen, forming a chemically amplified resist film on the film to be processed, and exposing the resist film to a desired pattern,
A resist pattern forming method comprising: a step of heat-treating the resist film; and a step of developing the resist film. 2. A step of bringing a surface of a film to be processed formed on a substrate to be processed into contact with a first compound that generates an acid by irradiation with actinic radiation, and irradiating the film to be processed with actinic radiation. A step of forming a resist film containing a second compound that generates an acid, a step of exposing the resist film to a desired pattern, a step of heat-treating the resist film, and a step of developing the resist film. A method for forming a resist pattern, comprising: 3. A step of rendering the surface of a film to be processed formed on a substrate to be processed hydrophobic, a step of heat treating the film to be processed, and a chemically amplified resist film formed on the film to be processed. And a step of exposing the resist film to a desired pattern, a step of heat-treating the resist film, and a step of developing the resist film.