JP2001249456A - Negative type resist composition and resist pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new negative type resist composition having improved sensitivity and resolution. SOLUTION: In the negative type resist composition, the molecular weight dispersity of a part insolubilized by exposure is 1-2. The composition contains a base resin comprising an alkali-soluble polymer, a photo-acid initiator capable of generating an acid when it absorbs radiation for image formation and degrades and an alicyclic alcohol having a reactive moiety capable of performing dehydration bonding reaction with the alkali-soluble group of the base resin in the presence of the acid generated from the photo-acid initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist composition, and more particularly to a chemically amplified negative resist composition which is developed with a basic aqueous solution after exposure.
The present invention also relates to a method for forming a high-sensitivity and high-resolution negative resist pattern using the negative resist composition. The resist composition and the method for forming a resist pattern according to the present invention can be advantageously used for manufacturing fine semiconductor devices such as LSIs.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, high integration of integrated circuits has progressed, and LSIs and VLSIs have been put into practical use. The capacity has increased to 1 gigabit, 4 gigabits, 16 gigabits,. Is 0.18μ
m, 0.15 .mu.m, 0.1 .mu.m... For this reason, it is essential to establish a fine processing technology, and in the lithography field, as a solution to the demand, the wavelength of the ultraviolet light of the exposure light source has been shifted to a shorter wavelength in the far ultraviolet region, and furthermore, in the deep ultraviolet region. It is said that an exposure technique using a light source having a wavelength of will soon be adopted in a mass production process. Accordingly, there is an urgent need to develop a resist material which has less light absorption at a short wavelength as described above and exhibits high sensitivity and high resolution. In addition, there is an urgent need to improve throughput in order to reduce costs.

In order to satisfy the above requirements, a photolithography technique using a krypton fluoride excimer laser (wavelength: 248 nm, hereinafter abbreviated as KrF) has been actively studied as a new exposure technique in the manufacture of semiconductor devices, and has been mass-produced. Are also being actively conducted. As a resist having a high sensitivity and a high resolution capable of coping with such a short wavelength light source, a resist composition using a concept called a chemical amplification type is disclosed by H.M. Ito et al. (JM Frechet et al., Proc. Microcircuit Eng., 2
60 (1982), H. Ito et al., Digest of Technical Paper
s of 1982 Symposium on VLSI Technology, 86 (1983),
H. Ito et al., "Polymers in Electronics", ACS S
ymposium Series 242, T. Davidson, ed., ACS, 11 (19
84), and U.S. Patent No. 4,491,628).

The above chemically amplified resist contains a base resin and a photoacid generator, and when exposed to imaging radiation, releases a small amount of acid from the photoacid generator, and subsequently releases heat. Addition (this heating is called “post-exposure bake” or “PEB”) causes an acid-catalyzed chain reaction to improve the apparent quantum yield and increase the sensitivity of the resist. In the above chemically amplified resist,
A positive resist for forming a positive pattern,
There is a negative resist for forming a negative pattern, but a positive resist has been mainly used in the past because of the availability of materials, the easiness of the process, and the obtained characteristics.

However, the development of a negative resist is also extremely important in industry. For example, one of the super-resolution techniques that have been actively studied in recent years is a method using a phase shift mask or a Levenson type mask that changes the phase of light. It is promising as a method for obtaining the resolution and sufficient depth of focus. When these masks are used, a negative resist is often suitable due to the limitation of the mask pattern. Therefore, there is a strong demand for providing a negative resist.

Looking at the negative chemically amplified resist, it is roughly divided into an alkali-soluble base resin, a photoacid generator which absorbs imaging radiation and decomposes to release an acid, and an acid catalyzed reaction. A substance called a polarity change type in which a substance causing a polarity change is contained in a resist, an alkali-soluble base resin, and a photoacid generator that absorbs imaging radiation and decomposes to release an acid And a substance called a cross-linking type in which a substance capable of causing a cross-linking reaction between resins is contained in a resist.

The former polarity-change type chemically amplified resist typically utilizes a pinacol transfer reaction,
For example, R. Sooriyakumaran et al. SPIE, 1466, 419 (199
1) and S. Uchino et al., SPIE, 1466, 429 (1991) disclose the technology. The acid-catalyzed reaction in such a resist proceeds as in the following formula (1).

[0008]

Embedded image That is, pinacol that is alkali-soluble changes to alkali-insoluble under the influence of acid and heat.
However, this type of chemically amplified resist has insufficient resolution. The reason is that pinacol itself changes to alkali-insoluble as described above due to the acid-catalyzed reaction, but the base resin itself does not become insoluble, so that a sufficient difference in solubility cannot be obtained.

The latter chemically amplified resist of the acid-catalyzed cross-linking reaction type typically utilizes a cross-linking reaction of an alkali-soluble resin with a melamine cross-linking agent such as methoxymethylol melamine.
al., J. Photopolym. Sci. Tech. 4, no.3 379 (1991)
A number of documents disclose the technology. The crosslinking reaction in such a resist proceeds as in the following formula (2).

[0010]

Embedded image When a melamine-based cross-linking agent is used as in this type of cross-linking type resist, a gelling reaction of the base resin (increase in molecular weight due to cross-linking of the base resin), a polar group of the resin (for example, a phenolic hydroxyl group), etc. The effect of reducing alkali dissolution by non-polarization resulting from crosslinking of the compound can be expected.
However, methoxymethylolmelamine used as a cross-linking agent has a low polarity in the first place, so that even with this type resist, a sufficient dissolution rate difference cannot be generated.

Therefore, it has been desired to provide a negative resist in which both the resin and the additive have a high polarity before the exposure and have a low polarity after the exposure.

[0012]

SUMMARY OF THE INVENTION The inventors of the present invention have previously made Japanese Patent Application No. 11-26081 as a resist meeting the above requirements.
No. 5 proposes a novel polarity-changeable high-performance negative resist composition. The proposed resist composition uses an alicyclic alcohol, preferably a tertiary alcohol having a sterically fixed structure, as an additive for insolubilizing alkali. This resist composition increases the difference in polarity between exposed portions and unexposed portions as compared with a conventional resist by a reaction represented by the following formula (3), thereby achieving high sensitivity, high contrast, and high resolution. This makes it possible to form a fine negative resist pattern having the same function.

[0013]

Embedded image And the present inventors, in relation to the negative resist,
As a result of further intensive studies, the present inventors have found suitable conditions for achieving higher sensitivity and higher resolution of the resist pattern, and have reached the present invention.

That is, the present invention focuses on the molecular weight dispersity of the base resin used on the first surface and makes it less than a predetermined value, and focuses on the molecular weight of the base resin used on the second surface. It has been found that by setting this to a predetermined range, it is possible to provide a negative resist composition with higher sensitivity and higher resolution, thereby completing the present invention.

Accordingly, it is a primary object of the present invention to provide a novel negative resist composition having dramatically improved sensitivity and resolution. Another object is to provide a method for forming a negative resist pattern using the novel negative resist composition.

[0016]

The object of the present invention is to provide a negative resist composition in which the molecular weight dispersity of a portion insolubilized by exposure is 1 or more and 2 or less, as described in claim 1, wherein the invention focuses on the molecular weight dispersity. Achieved by things.

According to the first aspect of the present invention, since the insolubilized portion is formed mainly by the reaction based on the change in polarity, there is no problem of swelling of the pattern, and the sensitivity and the resolution are greatly improved. Can provide things.

The molecular weight dispersity is a value obtained by calculating (weight average molecular weight / number average molecular weight). In conventional resists, the molecular weight varies greatly due to the crosslinking reaction, and the variation varies from molecule to molecule. Therefore, the molecular weight dispersity of the insolubilized portion is generally 3 to 4 or more. Yes, the resist composition of the present invention ranges from 1 to 2, and the polymer used is uniform. Since such a resist does not involve so-called "gelation" due to an increase in molecular weight, there is also an advantage that the resist after transferring a necessary pattern can be easily peeled off with an organic solvent or the like.

The negative resist composition according to claim 1 is decomposed by absorbing a base resin made of an alkali-soluble polymer and imaging radiation, as described in claim 2.
A photoacid generator capable of generating an acid, and an alicyclic alcohol having a reaction site capable of performing a dehydration bond reaction with an alkali-soluble group of the base resin in the presence of an acid generated from the photoacid generator. It can be configured as containing.

According to the second aspect of the present invention, since the composition contains an alkali-soluble group of the base resin and an alicyclic alcohol having a reaction site capable of performing a dehydration bond reaction, the polarity of the polymer when added to an alkali-soluble polymer is increased. The change can be increased and the etching resistance can be improved. Furthermore, since the molecular weight dispersity of the portion insolubilized by exposure is in the range of 1 or more and 2 or less, a negative resist composition having higher sensitivity and higher resolution can be obtained.

Further, in the negative resist composition, the molecular weight dispersion of the base resin is preferably 1 or more and 1.5 or less. When a base resin having such a molecular weight dispersion fraction is used, the molecular weight dispersion fraction of the portion insolubilized by exposure can be more reliably set to the range of 1 or more and 2 or less.

In the present specification, a resin having a molecular weight dispersity of 1 or more and 1.5 or less with respect to a base resin before exposure may be referred to as a “monodisperse resin”. The monodisperse resin only needs to be homogenized so as to fall within the above range, and the base resin may be constituted as a copolymer containing several different monomer units.

In the negative resist composition of the present invention, the weight average molecular weight of the base resin is preferably 2000 or more, and the weight average molecular weight of the base resin is preferably not less than 2000. Is more preferably 3,000 to 20,000. If the weight-average molecular weight of the base resin is too small, sensitivity and resolution are reduced. If the weight-average molecular weight is too large, the solubility is low, so that the dissolution rates before and after the reaction are low, and the solubility is unfavorably low. The most preferred weight average molecular weight range is from 5,000 to 10,000. When a base resin having a weight molecular weight within this range is used, a negative resist composition having high sensitivity and high resolution can be obtained. Here, the reason why the preferable molecular weight is specified by the weight average molecular weight is that the base resin is composed of a polymer.

The present invention also focuses on the molecular weight of each of the molecules of the polymer constituting the base resin used in the second aspect, and from the viewpoint of controlling the molecular weight, the alkali-soluble polymer according to claim 4 is used. And a photo-acid generator capable of generating an acid by absorbing and decomposing radiation for imaging, and an alkali of the base resin in the presence of an acid generated from the photo-acid generator. A negative resist composition comprising a soluble group and an alicyclic alcohol having a reactive site capable of performing a dehydration bond reaction, wherein the negative resist composition has a molecular weight of 20 in the base resin.
The above-mentioned object can also be achieved by a negative resist composition in which the components of 00 or less are 10% by weight or less.

The present inventors have confirmed that the use of a base resin containing a low-molecular-weight portion having a molecular weight of less than 2,000 sharply reduces the sensitivity and resolution of a resist. It is considered that such a low molecular weight portion is because the effect of inhibiting dissolution in a basic aqueous solution is unlikely to occur. Then, a low-molecular component having a molecular weight of 2000 or less is added to 1
It has been found that when the content is controlled to be 0% by weight or less, the influence of the above-mentioned inconveniences can be suppressed and a preferable negative resist composition can be obtained. This molecular weight 2000
It is more preferable that the following low molecular components be 3% by weight or less of the base resin. The molecular weight mentioned here is not the weight-average molecular weight described above, but is the (actual) molecular weight of each polymer molecule constituting the base resin.

As described above, the molecular weight in the base resin is 200
By setting the low molecular weight component, which is 0 or less, to 10% by weight or less, it is possible to obtain a resist composition having high sensitivity and high resolution. And a resist composition having high resolution.

Further, in the negative resist composition according to any one of claims 1 to 4, it is preferable that the base resin contains a phenolic polymer as described in claim 5. The phenolic resin is easy to adjust the molecular weight dispersity and to cut low molecular weight portions.

It is also preferable that the base resin is polyvinylphenol or a copolymer of vinylphenol and another monomer. Polyvinylphenol is preferably used as the base resin because it is easily available and easily monodispersed.

Further, in the negative resist composition according to any one of claims 1 to 5, it is preferable that the alicyclic alcohol has an adamantane structure as described in claim 6. When the alicyclic alcohol has an adamantane structure, insolubilization of the exposed portion can be further promoted.

The negative resist composition according to any one of claims 1 to 6, wherein the alicyclic alcohol has a tertiary alcohol structure having a stereochemically fixed structure. It is preferred to have. The alcohol having such a structure can further promote the insolubilization of the exposed portion.

In the negative resist composition according to the present invention, the tertiary alcohol is more preferably 1-adamantanol or a derivative thereof.

Further, in the negative resist composition according to any one of claims 1 to 8, the photoacid generator is selected from the group consisting of an onium salt, an organic halide, and a sulfonic acid ester. Preferably, the number is one.

In the negative resist composition according to the ninth aspect, the onium salt may be any one selected from the following formulas (A) to (D).

[0034]

Embedded image (Where X = CF ₃ SO ₃ , CF ₃ CF ₂ CF ₂ CF
₂ SO ₃ , SbF ₆ , AsF ₆ , BF ₄ , and PF _{6. In} the negative resist composition according to claim 9, the halogenated organic compound is a triazine having a halogen in the structure or a triazine having a halogen in the structure. An isocyanurate having a halogen may be used.

Further, as set forth in claim 10, the negative resist composition according to any one of claims 1 to 9 is applied on a substrate to be processed, and the formed resist film is irradiated with light of the resist composition. A method for forming a negative resist pattern comprising the above-described series of steps of selectively exposing the resist film after exposure to light with imaging radiation capable of exciting the decomposition of the acid generator and developing the exposed resist film with a basic aqueous solution, A sensitive and high-resolution resist pattern can be obtained.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a negative resist composition utilizing chemical amplification according to the present invention will be described as a preferred embodiment.

First, the negative resist composition comprises, as components directly involved in the reaction for forming a resist pattern, (1) a base resin made of an alkali-soluble polymer, and (2) radiation for imaging. (3) a photo-acid generator capable of absorbing and decomposing to generate an acid; and (3) having a reaction site for performing a dehydration bond reaction with the polymer of the base resin in the presence of the acid generated from the photo-acid generator. Alicyclic alcohols.

Each of the above components insolubilizes the exposed portion by the reaction represented by the above formula (3). Here, the reaction is explained in more detail by showing the formula (3) again. The alicyclic alcohol has a highly polar group such as an alcoholic hydroxyl group in the molecule. As the alicyclic alcohol, a tertiary alcohol having a stereochemically fixed structure is preferable. This is because the bond formed by the reaction between the alkali-soluble group of the base resin and the tertiary alcohol, for example, the ether structure is irreversibly fixed because of the three-dimensional structure. In this specification, the fact that it is difficult to regenerate to the state before the reaction based on the three-dimensional structure in this way is expressed as “stereochemically fixed”. Tertiary alcohols are preferred because they have high reactivity and easily cause a dehydration reaction. Due to the presence of an acid catalyst, such a substance reacts with a polar group (such as a phenolic hydroxyl group) of the base resin and is stably esterified or etherified.

In the following reactions shown in the examples, a reaction example in which polyvinyl phenol is used as a base resin and 1-adamantanol having a tertiary structure is added as an alicyclic alcohol will be described. .

[0040]

Embedded image By this one reaction, both the phenolic hydroxyl group of the base resin and the alcoholic hydroxyl group of the alicyclic alcohol are etherified, the polarity changes, and both become alkali-insoluble. That is, through this reaction, both the base resin and the alicyclic alcohol having high polarities before the exposure become low polarities after the exposure. Therefore, the exposed portion is insolubilized in the basic aqueous solution, and a negative pattern having high sensitivity and high resolution can be formed.

The route of the acid catalyzed reaction is the same as that described in the first embodiment.
In addition to pathways, other reactions can also occur incidentally. For example, a reaction in which adamantanol is added to a carbon atom located adjacent to a phenolic hydroxyl group of the base resin, a reaction in which adamantanol condenses with each other, and the like can be mentioned. These ancillary reactions also contribute to a decrease in polarity due to steric hindrance caused by proximity to a hydroxyl group.

In the above resist composition, the alicyclic alcohol used as the third reaction component is
Having a reaction site capable of performing a dehydration bond reaction with a base resin (alkali-soluble polymer) as a first reaction component in the presence of an acid generated from the photoacid generator and a reaction component of It is. This resist composition has the following advantages by using an alicyclic alcohol. (1)
Due to the bulky structure, a large change in polarity when added to the alkali-soluble polymer can be obtained, and (2) high etching resistance can be obtained when used as a resist.

According to the inventor's intensive studies, the negative resist of the present invention should have a molecular weight dispersity of 1.5 or less, preferably 1.3 or less with respect to the base resin. Further, by using a resin having a weight average molecular weight within a predetermined range, higher sensitivity and higher resolution are achieved.

The smaller the molecular weight dispersity of the base resin used, the more favorable the insolubilization reaction of the exposed portion can be caused. It is presumed that by reducing the molecular weight dispersity of the base resin to make the molecular weight uniform, each molecule becomes almost insoluble at the same time. When a negative resist composition using such a monodispersed resin as a base resin is exposed, the ratio is very small even when the case where the base resin is directly cross-linked by imaging radiation is considered. Thereafter, the molecular weight dispersity value of the portion does not exceed 2.

Further, by not including the above-mentioned portion having a weight molecular weight of 2,000 or less, preferably in the range of 3,000 to 20,000, a resist composition having further improved sensitivity and resolution can be obtained. In order to obtain a resist having higher sensitivity and higher resolution, it is recommended that the weight molecular weight be in the range of 5,000 to 10,000.

When the base resin is monodispersed, a blend of polymers having different weight molecular weights may be used. That is, even if the base resin is formed by blending polymers having different weight molecular weights of, for example, 5,000, 6000, and 7000 without including a portion having a weight molecular weight of 2,000 or less, the original monodispersed state is maintained. The same effect can be obtained.

Since the dispersing rate of a monodisperse resin in a developing solution is generally very high, the dispersing rate is adjusted so as to decrease the dissolving rate as a copolymer of another monomer (eg, styrene, methoxystyrene, etc.) and vinylphenol. You may. In order to reduce the dissolution rate of the monodisperse resin, a small amount of novolak having a relatively low dissolution rate may be added.

The (actual) molecular weight of each molecule of the polymer constituting the base resin is 2%.
By controlling so as not to include a low molecular weight polymer having a molecular weight of 000 or less, it is possible to increase the sensitivity and resolution of the resist. The present inventors have presumed that such low molecular components hardly contribute to the effect of insolubilization, so that the sensitivity of the resist decreases.

When a base resin having a content of a low molecular component having a molecular weight of 2,000 or less of 10% by weight or less, preferably 3% by weight or less is used, a practically useful resist composition having high sensitivity and high resolution can be used. Can form an object. Here, as described above, it is preferable that the base resin is a monodisperse system. However, it is possible to obtain a preferable negative resist composition only by suppressing the content of the low molecular weight portion low.

As the base resin described in detail above, a polymer generally used conventionally can be used, and it is preferable to use a phenol resin. As the phenolic resin, novolak-based phenol novolak, cresol novolak, and vinyl-based polyvinylphenol can be used, but polyvinylphenol, which is easy to adjust the molecular weight dispersity and cut the low molecular weight portion, is used. Is more preferable.

The adjustment of the degree of molecular weight dispersion of the base resin and the cutting of the low molecular weight portion can be carried out by using a living anion polymerization method or a fractionation method such as gel permeation chromatography (GPC).

The above-mentioned effect obtained by making the base resin monodisperse can be seen in an alicyclic alcohol having a plurality of hydroxyl groups, but the polarity-change type of the above-mentioned formula (3) which does not involve a crosslinking reaction. This is particularly noticeable in a reaction system. That is, in the negative (insolubilizing) reaction of the resist of the present invention, a polarity change mainly occurs, and there is almost no increase in molecular weight. Therefore, no swelling occurs during development. Therefore, when the monodisperse resin is used as the base resin as described above, the molecular weight dispersity of the insolubilized portion after exposure is 2 or less, even in consideration of the case where the molecular weight increases due to direct crosslinking by the imaging radiation. Become.

Next, the alicyclic alcohol as the third reaction component and the photoacid generator as the second component will be described below.

As the alicyclic alcohol, those having the following structures can be used.

[0055]

Embedded image The amount of the alicyclic alcohol is about 2 to 60 parts, more preferably 15 to 40 parts, per 100 parts of the base resin. If the amount of the alicyclic alcohol is too small, the change in polarity due to the reaction is so small that the contrast required for a negative resist cannot be obtained. On the other hand, if the amount of the alicyclic alcohol is too large, a large amount of exposure is required to complete the reaction of the substituent, which is uneconomical. Further, when a large amount of alicyclic alcohol is added, the thermal characteristics of the entire resist composition are degraded, and problems such as precipitation during resist coating occur.

Further, as the second component photoacid generator,
General photoacid generators for resists, such as various halogenated organic substances, sulfonic acid esters, and onium salts, can be used. As the halogenated organic substance, those having the following structures can be used.

[0057]

Embedded image As the usable sulfonic acid ester, those having the following structures can be used.

[0058]

Embedded image However, an onium salt is particularly effective in inducing a binding reaction, and its use is particularly preferred. As the usable onium salts, those having the following structures can be used.

[0059]

Embedded image (Where X = CF ₃ SO ₃ , CF ₃ CF ₂ CF ₂ CF
₂ SO ₃ , SbF ₆ , AsF ₆ , BF ₄ , PF ₆ ) The amount of the photoacid generator is from 1 part to 3 parts per 100 parts of the base resin.
A range of 0 parts is preferred. If the amount is less than this, the progress of the reaction is reduced due to the small amount of acid generated even after exposure. This causes a decrease in sensitivity. On the other hand, if there are too many,
Troubles such as deposition may easily occur during coating, and the thermal characteristics of the resist may be deteriorated. In consideration of sensitivity and resolution, about 2 to 10 parts is particularly preferable.

Baking after exposure, so-called PEB is 60 to 1
The temperature range is 80 ° C, more preferably 90 to 120 ° C. If the temperature is too low, the effect of exciting the acid-catalyzed reaction by the acid is so small that the sensitivity cannot be improved. If the temperature is too high, a desired pattern size cannot be obtained due to an abnormal increase in the reaction amount.

Another object of the present invention is to provide a method for forming a negative resist pattern on a substrate to be processed using the novel resist composition as described above. The formation of the resist pattern of the present invention can be usually carried out as follows.

First, the resist composition of the present invention is applied on a substrate to be processed to form a resist film. The substrate to be processed can be a substrate usually used in semiconductor devices and other devices, and examples of the substrate include a silicon substrate, a glass substrate, and a non-magnetic ceramic substrate. Further, on these substrates, if necessary, additional layers such as a silicon oxide film layer, a metal layer for wiring, an interlayer insulating film layer, and a magnetic film may be present.
Further, various wirings, circuits, and the like may be formed. Further, these substrates may be subjected to a hydrophobic treatment according to a standard method in order to increase the adhesion of the resist film to the substrates. Suitable hydrophobizing agents include, for example, 1,1,1,
3,3,3-hexamethyldisilazane (HMDS) and the like can be mentioned.

As described above, the resist composition can be applied as a resist solution onto a substrate to be processed. The application of the resist solution may be a conventional technique such as spin coating, roll coating, or dip coating, and spin coating is particularly useful. The resist film thickness is about 0.1 ~
A range of 200 μm is recommended, but in the case of exposure with an excimer laser such as KrF or ArF, 0.1 to 15 μm
Range is recommended. Note that the thickness of the formed resist can be widely changed depending on factors such as the use thereof.

The resist film applied on the substrate is heated to about 60 to 180 ° C. before selectively exposing the resist film to the imaging radiation.
Prebaking at a temperature of about 30 to 120 seconds. This pre-bake can be performed by using a usual heating means in the resist process. Suitable heating means include, for example, a hot plate and an infrared heating oven.

Next, the resist film after prebaking is selectively exposed to radiation for image formation using a conventional exposure apparatus. Suitable exposure apparatuses include commercially available ultraviolet (far ultraviolet and deep ultraviolet) exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, and the like. Exposure can be selected under appropriate conditions each time. In particular, in the present invention, as described above, an excimer laser (a KrF laser having a wavelength of 248 nm and an ArF laser having a wavelength of 193 nm) can be advantageously used as an exposure light source. In addition, in the present specification, the use of the term “radiation” means radiation from any of these light sources.

By subjecting the exposed resist film to PEB, a polarity change occurs in which an alkali-soluble group is insoluble in a basic aqueous solution mainly by a protective reaction using an acid as a catalyst. This post-exposure bake can be performed in the same manner as the pre-bake as long as the protective reaction is sufficiently generated. For example, the baking temperature can be about 60-180 ° C. for about 30-120 seconds,
It is preferable to adjust according to a desired pattern size, shape, and the like.

After PEB, the resist film is developed with a basic aqueous solution as a developing solution. For this development, a conventional developing device such as a spin developer, a dip developer, or a spray developer can be used. Here, the basic aqueous solution used as the developer is not particularly limited, but may be an aqueous solution of a metal hydroxide belonging to Group I or II represented by potassium hydroxide or the like, or a metal ion such as tetraalkylammonium hydroxide. An organic basic aqueous solution that does not contain an organic basic solution may be used, but an aqueous solution of tetramethylammonium hydroxide (TMAH) is more preferable, and an additive such as a surfactant may be added to improve development hardening. As a result of the development, the unexposed area of the resist film is dissolved and removed, and only the exposed area remains on the substrate as a negative resist pattern. [Examples] Next, examples relating to preparation of a resist composition of the present invention and formation of a resist pattern will be described.

The following components (I) of a polyvinylphenol-based base resin, (II) a photoacid generator and (III) an alicyclic alcohol were prepared as components constituting the resist composition according to the examples. (I) Base resin (polyvinyl phenol) 1) Weight average molecular weight 12,000, molecular weight dispersity 2.0 (conventional product) 2) Weight average molecular weight 3,200, molecular weight dispersity 1.15 3) Weight average molecular weight 5 000, molecular weight dispersity 1.11 4) weight average molecular weight 10,000, molecular weight dispersity 1.11 2) +3) +4) (II) photoacid generator

[0069]

Embedded image (III) Alicyclic alcohol

[0070]

Embedded image A resist solution was prepared by dissolving ethyl lactate in combination with the above components, and compared with a commercially available negative resist composition (melamine-based) and a pinacol-based resist prepared for comparison. The resist composition and the pinacol-based resist of the present example were prepared by using a base resin: an alicyclic alcohol:
Photoacid generator = 10: 2: 1 (weight ratio). The obtained resist solution was filtered through a 0.2 μm Teflon ^TM membrane filter, and then spin-coated at 2000 rpm on a HMDS-treated silicon substrate.
Prebaked for 2 minutes at ° C. The pinacol used in the description of the prior art was used. Since the three melamine-based resists are commercially available products, their detailed compositions are unknown.

The resist film obtained above was subjected to pattern exposure using the following three types of exposure apparatuses.

(1) i-ray exposure apparatus (wavelength 365 nm) (2) KrF excimer laser stepper (NA = 0.4
(5, wavelength: 248 nm) (3) Electron beam exposure apparatus (output: 50 kV) The exposure pattern is 0.4 μm line and space (L / S) for i-line and 0.25 μmL / for KrF laser.
S, and the electron beam was 0.2 μmL / S. Subsequently, a post-exposure bake (PE) was performed at 120 ° C. for 2 minutes.
After B), the film was developed with an aqueous solution of 2.38 tetramethylammonium hydroxide (TMAH) for 30 seconds and rinsed with deionized water for 60 seconds. The resolution of the obtained negative resist pattern was evaluated. Table 1 compares the prepared resist compositions and shows the results.

[0073]

[Table 1] The four-level evaluation symbols, ◎, ◎, Δ, and × used in Table 1 above are as follows.

A: The cross-sectional shape of the formed pattern is rectangular. The difference between the pattern top dimension and the pattern bottom dimension is less than 0.5% of the exposure pattern dimension.

：: The cross-sectional shape of the formed pattern is rectangular. The difference between the pattern top dimension and the pattern bottom dimension is within 0.5 to 1% of the exposure pattern dimension.

Δ: The cross-sectional shape of the formed pattern is substantially rectangular. The difference between the pattern top dimension and the pattern bottom dimension is within 1 to 5% of the exposure pattern dimension.

X: The cross-sectional shape of the formed pattern is slightly tapered. The difference between the pattern top dimension and the pattern bottom dimension is greater than 5% of the exposure pattern dimension.

From the results shown in Table 1, it can be confirmed that the negative resist composition of this example has high sensitivity and high resolution as compared with the cited general conventional product.

Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the specific embodiments, and various modifications may be made within the scope of the present invention described in the appended claims. Can be modified and changed.

The following items are further disclosed with respect to the above description.

(1) A negative resist composition wherein the molecular weight dispersity of the portion insolubilized by exposure is 1 or more and 2 or less.

(2) A base resin composed of an alkali-soluble polymer, a photoacid generator capable of absorbing and decomposing imaging radiation to generate an acid, and a photoacid generator generated from the photoacid generator. Item 2. The negative resist composition according to item 1, which contains an alkali-soluble group of the base resin and an alicyclic alcohol having a reaction site capable of performing a dehydration bond reaction in the presence thereof.

(3) The molecular weight dispersion of the base resin is 1
Item 3. The negative resist composition according to item 1 or 2, wherein the content is 1.5 or less.

(4) The negative resist composition according to item 2 or 3, wherein the weight average molecular weight of the base resin is 2,000 or more.

(5) The negative resist composition according to item 4, wherein the base resin has a weight average molecular weight of 3,000 to 20,000.

(6) A base resin made of an alkali-soluble polymer, a photoacid generator capable of absorbing an imaging radiation and decomposing to generate an acid, and the presence of an acid generated from the photoacid generator A negative resist composition containing an alkali-soluble group of the base resin and an alicyclic alcohol having a reaction site capable of performing a dehydration bond reaction, wherein the molecular weight of the base resin is 2,000 or less. A negative resist composition comprising 10% by weight or less of a component.

(7) The negative resist composition according to any one of Items 1 to 6, wherein the base resin contains a phenolic polymer.

(8) The negative resist composition according to item 7, wherein the base resin is polyvinyl phenol or a copolymer of vinyl phenol and another monomer.

(9) The negative resist composition according to any one of Items 1 to 8, wherein the alicyclic alcohol has an adamantane structure.

(10) The negative resist composition according to any one of items 1 to 9, wherein the alicyclic alcohol has a tertiary alcohol structure having a stereochemically fixed structure.

(11) The negative resist composition according to item 10, wherein the tertiary alcohol is 1-adamantanol or a derivative thereof.

(12) The photoacid generator is an onium salt,
Items 1 to 11 characterized by being one selected from the group consisting of halogenated organic substances and sulfonic acid esters
The negative resist composition according to any one of the above.

(13) The negative resist composition according to item 12, wherein the onium salt is any one selected from the group consisting of the compounds (A) to (D).

(14) The negative resist composition according to item 12, wherein the halogenated organic substance is a triazine having a halogen in the structure or an isocyanurate having a halogen in the structure.

(15) The negative resist composition according to any one of Items 1 to 14, is applied onto a substrate to be processed, and the formed resist film is used for imaging capable of exciting the decomposition of the photoacid generator in the resist composition. A method of forming a negative resist pattern, comprising the above series of steps of selectively exposing to light with radiation and developing the exposed resist film with a basic aqueous solution.

[0096]

As is clear from the above description, according to the first aspect of the present invention, since the insolubilized portion is formed mainly by the reaction based on the change in polarity, the problem of swelling of the pattern occurs. Thus, a negative resist composition having dramatically improved sensitivity and resolution can be provided. According to the second and third aspects of the present invention, since an alkali-soluble group of the base resin and an alicyclic alcohol having a reaction site capable of performing a dehydration bond reaction are contained, it is added to an alkali-soluble polymer. Sometimes the polarity change can be increased, and the molecular weight dispersity of the part insolubilized by exposure,
Alternatively, since the weight average molecular weight is within a predetermined range, a negative resist composition having higher sensitivity and higher resolution can be obtained. Further, according to the invention of claim 4, a negative resist composition having high sensitivity and high resolution can be obtained. Further, according to the invention of claims 7 to 9, a more preferable negative resist composition can be formed.
Further, according to the tenth aspect, a resist pattern having high sensitivity and high resolution can be obtained.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) C08L 101/14 C08L 101/14 H01L 21/027 H01L 21/30 502R (72) Inventor Junichi Ima Nakahara-ku, Kawasaki City, Kanagawa Prefecture 4-1-1 Kamiodanaka, Fujitsu Limited (72) Inventor Koji Nozaki 4-1-1, Kamikadanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited (72) Miwa Ozawa Nakahara-ku, Kawasaki City, Kanagawa Prefecture 4-1-1 Kamiodanaka F-term within Fujitsu Limited (Reference) 2H025 AA01 AA02 AB16 AC04 AC08 AD01 BD01 BE00 BE07 BE08 BE10 BJ05 CB17 CB28 CB43 CB45 CC17 CC20 FA01 FA12 4J002 AA051 BC121 CC031 EB076 EB106 EC246 EU196 EU196 EU196 186 FD207 4J100 AB07P BA02H BA02P BA03P BC04H BC04P BC07H BC07P BC09H BC09P BC12H BC12P BC43H BC43P CA01 CA04 HA19 HC09 JA38

Claims (10)

[Claims] 1. A negative resist composition wherein the molecular weight dispersity of a portion insolubilized by exposure is 1 or more and 2 or less. 2. A base resin comprising an alkali-soluble polymer, a photoacid generator capable of absorbing and decomposing imaging radiation to generate an acid, and the presence of an acid generated from the photoacid generator. 2. The negative resist composition according to claim 1, further comprising an alkali-soluble group of the base resin and an alicyclic alcohol having a reaction site capable of performing a dehydration bonding reaction. 3. The weight average molecular weight of the base resin is 200.
3. The negative resist composition according to claim 2, wherein the value is 0 or more. 4. A base resin composed of an alkali-soluble polymer, a photoacid generator capable of absorbing an imaging radiation and decomposing to generate an acid, and an acid generated from the photoacid generator. ,
A negative resist composition comprising an alkali-soluble group of the base resin and an alicyclic alcohol having a reaction site capable of performing a dehydration bond reaction, wherein a component having a molecular weight of 2,000 or less in the base resin is A negative resist composition, wherein the content is 10% by weight or less. 5. The negative resist composition according to claim 1, wherein the base resin contains a phenolic polymer. 6. The negative resist composition according to claim 1, wherein the alicyclic alcohol has an adamantane structure. 7. The negative resist composition according to claim 1, wherein the alicyclic alcohol has a tertiary alcohol structure having a stereochemically fixed structure. 8. The negative resist composition according to claim 7, wherein the tertiary alcohol is 1-adamantanol or a derivative thereof. 9. The negative resist according to claim 1, wherein the photoacid generator is one selected from the group consisting of an onium salt, a halogenated organic compound, and a sulfonic acid ester. Composition. 10. The negative resist composition according to claim 1, which is applied on a substrate to be processed, and the formed resist film can excite decomposition of a photoacid generator of the resist composition. A method for forming a negative resist pattern, comprising the above series of steps of selectively exposing to light with imaging radiation and developing the exposed resist film with a basic aqueous solution.