JPH05323613A - Radiation sensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain a novel radiation sensitive resin compsn. having high sensitivity to radiation and excellent resistance to reactive ion etching with O2. CONSTITUTION:This radiation sensitive resin compsn. is a mixture of 0.5g polysiloxane represented by the formula and having 3,500wt. average mol.wt. and 1.2 specific dispersion with 50mg triphenylsulfonium trifluoromethanesulfonate and 4ml 2-ethyl methoxyacetate as a solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can be used as a constituent material of a resist used in the manufacture of semiconductor devices and the like, and is a novel radiation sensitive material which is sensitive to radiation such as light, electron beam, X-ray or ion beam. Resin composition.

[0002]

2. Description of the Related Art With the high integration of LSIs, a processing technique on the order of submicrons is required. for that reason,
For example, in an etching process in the manufacture of LSI, a dry etching technique that enables highly precise and fine processing is adopted.

Here, the dry etching technique means that a substrate to be processed is covered with a resist, the resist is patterned by using light or an electron beam, and the obtained pattern is used as a mask to react the substrate with reactive gas plasma. This is a technique for etching the portion exposed from the mask. Therefore, the resist used in the dry etching technique is composed of a material having a resolution of submicron order and sufficient resistance to reactive gas plasma.

However, since the step difference of the substrate to be processed becomes larger as the integration of the LSI becomes higher, the thickness of the resist layer is made flat so that the resist remains as a mask until the end of the substrate processing. So that it tends to be thicker. Therefore, in the case of light exposure, there is a restriction due to the depth of focus of the exposure optical system, and in the case of electron beam exposure, there is a restriction due to the phenomenon of electron scattering in the resist. It is becoming difficult to perform fine etching with precision. Therefore, various new resist processes have been studied, and a two-layer resist process has received attention as one of them.

This two-layer resist process is a thick polymer layer for flattening the steps of the substrate (usually a layer of polyimide or thermoset photoresist is used).
And a thin photoresist layer having O ₂ -RIE resistance formed thereon and used as a mask during substrate etching. A high resolution is secured by the thin resist layer which is the upper layer resist, and dry etching resistance during substrate processing is secured by the lower layer resist.

A silicon-containing polymer having a higher O ₂ -RIE resistance than the lower layer is suitable as a constituent material of the upper layer resist used in the two-layer resist process. A typical example thereof is a photocurable silicone resin. this is,
A silicone resin as a binder mixed with a photocrosslinking agent or a photopolymerization initiator, which can be used as a negative resist.

As a specific example of such a photocurable silicone resin, there is one disclosed in Japanese Patent Laid-Open No. 61-20030. This is composed of a resin having a double bond such as poly (acryloyloxymethylphenylethylsilsesquioxane) and bisazide, and could be used as a highly sensitive negative resist for ultraviolet rays under a nitrogen atmosphere.

As another example, Japanese Patent Publication No. 60-496
There is one disclosed in Japanese Patent No. 47. This is a system using polysilane as a photopolymerization initiator. Specifically, it has been shown that a composition of poly (organosiloxane) having a double bond and dodecamethylcyclohexasilane has good properties as an ultraviolet curable resin.

As another example, Japanese Patent Application Laid-Open No. 55-127.
There was one disclosed in Japanese Patent No. 023. this is,
This is a system using an organic peroxide as a photopolymerization initiator. This publication shows that by using various organic peroxides such as peroxyesters together with poly (organosiloxane) having a double bond, a uniform cured film can be obtained by UV irradiation. There is.

[0012] Further, there is one disclosed, for example, in Japanese Patent Laid-Open No. 1146446/1991, which is completely different from the one described above. This is OFPR-800
For general-purpose positive photoresists such as (Tokyo Ohka Kogyo Co., Ltd.), poly (phenylsilsesquioxane) and cis- (1,3,5,7-tetrahydroxy) -1,3,5,7 are used. -A small amount of tetraphenylcyclotetrasiloxane was added. According to this, a positive resist for the two-layer resist method, which was developable with an alkaline solution, was obtained.

It is also considered to use a binder other than poly (siloxane). For example, Japanese Patent Application Laid-Open No. 61-198151 discloses that a novolak resin having a trialkylsilyl group is used as a diazonaphthoquinone photosensitizer to form an upper layer resist having sensitivity to visible light.

[0012]

However, each conventional resist (photosensitive resin composition) has the following problems.

First, since the photo-curing reaction which proceeds through organic radicals is generally inhibited by oxygen, a photosensitive resin composition using this type of reaction, for example, JP-A-61-200.
The exposure of the publication of No. 30 is, as seen in that publication,
High sensitivity cannot be achieved unless it is performed in a nitrogen atmosphere. This can also be said for the product disclosed in JP-A-55-127023, so that this product has a drawback that it takes a long time to cure although the properties of the cured film are improved. Further, according to the knowledge of the inventor of this application, it is difficult to realize a sufficiently high sensitivity for the product disclosed in Japanese Patent Publication No. 60-49647, though it is not as great as when bisazide is used, because of the presence of oxygen. I know that.

On the other hand, in the material disclosed in JP-A-61-144639, the addition amount of the silicon compound cannot be increased so much, and in the material disclosed in JP-A-61-198151, the silicon content in the binder used. However, none of them had a sufficient resistance to O ₂ -RIE. In addition, although these photosensitive resin compositions are formed by the same idea as a general-purpose positive photoresist having excellent fine workability, they are disclosed in JP-A-61-1.
Since the material disclosed in Japanese Patent No. 44639 discloses the addition of polysiloxane, and the material disclosed in Japanese Patent Application Laid-Open No. 61-198151 uses a silicon-containing novolac resin, it is realized by a general-purpose positive photoresist. It is difficult to maintain the difference in dissolution rate in the developing solution between the exposed and unexposed areas as it is.

Therefore, each of the conventional photosensitive resin compositions is
There are drawbacks that the throughput of manufacturing a semiconductor device cannot be increased, the resist pattern becomes thin during etching, and highly accurate substrate processing cannot be performed, or high resolution cannot be obtained.

The present invention has been made in view of the above points, and therefore an object of the present invention is to provide a radiation-sensitive resin composition having high sensitivity to radiation and excellent O ₂ -RIE resistance. To provide.

[0017]

In order to achieve this object, the radiation-sensitive resin composition of the present invention (hereinafter sometimes abbreviated as "composition") has the above-mentioned features. It is characterized by containing poly (siloxane) as a first component represented by the formula (1) and an acid generator as a second component that decomposes to generate an acid by the action of irradiation radiation. However, n is the degree of polymerization.

According to this structure, the poly (siloxane) used as the first component is a poly (siloxane) having a p-allyloxyphenyl group in its side chain. Since this p-allyloxyphenyl group causes cationic polymerization in the presence of acid, it functions as a crosslinking group. This is for example document I (Journal of Polymer Science, Part A-1 (J.
Polym.Sci.PartA-1), 5, 1254 (1967)) and in Reference II (Journal of Polymer Science Polymer Letter Edition (J.Polym.
Sci. Polym. Lett. Ed.), 17, 79 (1979)), it was reported that allyl (p-vinylphenyl ether) causes cationic polymerization and radical polymerization at the allyl position at high temperature (20 ° C). You can tell from the fact that you are there. Therefore,
When the composition of the present invention is selectively irradiated with radiation such as light, electron beam, X-ray, or ion beam, the acid generator in the irradiated portion generates an acid, and the acid generates poly (siloxane) in the irradiated portion. ) And acts on the p-allyloxyphenyl group to cause crosslinking at this portion. Therefore, the radiation-exposed portion of this composition becomes insoluble in the developer. The manner in which the above-mentioned crosslinking occurs in the radiation-irradiated portion of this composition is shown in the following formula (2).

[0019]

[Chemical 2]

On the other hand, in the non-irradiated portion of this composition, an appropriate amount of heat is applied to the composition (a temperature at which the Claisen rearrangement described below can occur and at which the thermal acid generator is not thermally decomposed). (About 100 to 180 ° C. is preferable.), The p-allyloxyphenyl group is changed to a p-hydroxy-m-allylphenyl group by Claisen rearrangement. Since the p-hydroxy-m-allylphenyl group is soluble in an alkaline solution, the non-irradiated portion of this composition can be selectively removed by an alkaline developer. The state of Claisen rearrangement in the non-irradiated portion of this composition is shown in the following formula (3).

[0021]

[Chemical 3]

Therefore, according to the present invention, a radiation-sensitive resin composition capable of forming a negative resist pattern with an alkaline developer is realized.

The suitable molecular weight range of the first component, poly (siloxane), can be arbitrarily selected according to the coating property of the radiation-sensitive resin composition on a substrate. If the radiation-sensitive resin composition is used as a resist, for example, it is possible to form a solid film, be soluble in a solvent for preparing a resist coating solution, and be easy to filter with a filter. , It is necessary to obtain the desired resolution, so its molecular weight is 500-
100,000 It is good to set it as the range of 1000-10000 preferably.

Further, the cross-linking of the poly (siloxane) as the first component at the irradiated portion is caused by the action of a small amount of acid from the acid generator as the second component, and therefore the radiation-sensitive resin composition. Since the exposure amount at the time of exposing the composition will be an exposure amount capable of generating a desired (catalytic amount) acid from the acid generator, the composition becomes highly sensitive.

Further, since poly (siloxane) as the first component has a silicon-oxygen bond in the main chain, it can be efficiently converted into silicon dioxide during the process of treatment with oxygen plasma, so that dry etching resistance is also secured. It

As the acid generator which is the second component of the radiation-sensitive resin composition of the present invention, various conventionally known ones can be used. However, hydrohalic acid is not very suitable because it has a weak catalytic action. For example, various sulfonium salts represented by the following formula (I) and formula (II), various iodonium salts represented by the following formula (III) and formula (IV), and the following formula (V)
And various aromatic compounds having at least one trichloromethyl group as represented by the formula (VI), various p-toluenesulfonates represented by the following formula (VII), and the like. It is preferable because it generates a stronger acid.

[0027]

[Chemical 4]

[0028]

[Chemical 5]

However, X in the formulas (I) to (IV)
^- is, for example, _{^{BF 4 -, AsF 6 -,}} SbF 6 -, Cl
Represents O ₄ ⁻ or CF ₃ SO ₃ ^−, and R ¹ in the formula (V) is, for example, CCl ₃ or the above formula (A),
Represents a group represented by (B), (C), (D) or (E), R ² in formula (VI) is, for example, Cl or H, and R ³ is, for example, Cl or CCl ₃ . And R ⁴ in formula (VII) represents, for example, a group represented by formula (F) or formula (G) above.

The above-mentioned acid generators are commercially available or, for example, JV Crivero (JV Cri).
Velo) [Journal of Polymer Science, Polymer Chemistry Edition (J. Polymer Sci., Polymer C
hem. Ed. , 18, 2677 (1980)] and [22, 69 (1984)].

These acid generators are preferably added in an amount of 0.01 to 50% by weight, preferably 0.05 to 30% by weight, based on the weight of the poly (siloxane) used. If it is out of this range, the sensitivity of the radiation-sensitive resin composition will be low, or the coating film will be fragile.

When the radiation-sensitive resin composition is used, when the composition is applied onto a substrate by spin coating to form this film on the substrate, a solvent for preparing a coating solution for that purpose is required. Examples of this solvent include 2-methoxyethyl acetate, methyl isobutyl ketone (MIBK), cellosolve acetate, methyl cellosolve acetate, dioxane and the like.

In using the radiation-sensitive resin composition, the film of the composition is irradiated with radiation and then the sample is heat-treated to promote enhancement of the action of the acid generator in the radiation-irradiated portion. be able to.

[0034]

EXAMPLES Examples of the radiation-sensitive resin composition of the present invention will be described below. However, the materials used and the numerical conditions such as the amount thereof, the processing time, the processing temperature, and the film thickness mentioned in the following description are only suitable examples within the scope of the present invention. Therefore, the present invention is not limited to these conditions.

1. Synthesis of poly (siloxane) represented by formula (1) 1-1. Synthesis of p-hydroxy-m-allylphenyltrimethoxysilane First, p-hydroxy-m-allylphenyltrimethoxysilane as a silane monomer for obtaining the poly (siloxane) represented by the formula (1) was prepared as follows. To synthesize.

122 g of p-hydroxybenzaldehyde
Is dissolved in 1 liter of THF (tetrahydrofuran), and then 248 g of allyl bromide is added dropwise to this solution. The solution is stirred overnight at room temperature, after which potassium bromide is filtered off. THF from this filtrate
Is distilled off and the residue is distilled under reduced pressure to obtain 105 g of p-allyloxybenzaldehyde.

Next, 25.5 g of methyltriphenylphosphonium bromide, 7.8 g of potassium t-butoxide and 1
0.5 g of 8-crown-6-ether is dissolved in 150 ml of dry THF and this solution is cooled with water. 10.5 of the above-mentioned p-allyloxybenzaldehyde was added to this solution.
What melt | dissolved g in 100 ml THF is dripped in 10 minutes. The solution is returned to room temperature and then reacted overnight.
After extracting the reaction product with ethyl acetate / water, the solvent is distilled off from the organic layer. The residue is purified by silica gel chromatography to give 6.5 g of p-allyloxystyrene.

Next, 5.0 g of trimethoxysilane was put into a reactor purged with nitrogen, and 1 mol / mol thereof was further added.
Add a few drops of an IPA (isopropyl alcohol) solution of chloroplatinic acid at a concentration of 1 (liter). After 15 minutes, 10 g of the above-mentioned p-allyloxystyrene 6.5 g was placed in this reactor.
What was dissolved in ml of toluene is added. After reacting the one in the reactor for 16 hours at a temperature of 60 ° C., it is cooled, diluted with cyclohexane and then filtered through Celite. The filtrate was evaporated under reduced pressure to give p-hydroxy-m-allylphenethyltrimethoxysilane 10
g is obtained.

1-2. Polymerization of silane monomer 10 g of p-hydroxy-m-allylphenethyltrimethoxysilane synthesized as described above is dissolved in 240 ml of methyl isobutyl ketone (MIBK), and 1.0 g of triethylamine and 15 ml of water are added to this solution. The liquid is heated to 60 ° C. and reacted for 16 hours. After cooling, it is diluted with MIBK and then washed with water. The organic layer is distilled off under reduced pressure to obtain 5 g of polymer.

Next, this polymer is dissolved in 20 ml of THF, and 2 ml of trimethylchlorosilane and 2 ml of triethylamine are added to this solution and reacted overnight.
The reaction product is extracted with MIBK / water, the organic layer is distilled under reduced pressure to obtain a polymer, and the polymer is precipitated in methanol to obtain 4 g of the target poly (siloxane).

The molecular weight of this polymer was measured by GPC (gel permeation chromatography) to find that Mw = 35.
00, Mw / Mn = 1.2.

2. Preparation of composition (resist solution) Poly (siloxane) synthesized as described above (Mw = 35
00, Mw / Mn = 1.2) 0.5 g, and 50 mg of triphenylsulfonium trifluoromethanesulfonate as an acid generator (in formula (I), X ⁻ is CF ₃ SO ₃ ^— ). Mix with 4 ml of ethyl 2-methoxyacetate. The composition of Example (resist solution) was obtained by filtering this with a membrane filter having pores with a diameter of 0.2 μm.
To prepare.

3. Patterning Experiment The resist solution of the example prepared as described above is applied on a silicon wafer by spin coating. This silicon wafer is prebaked for 1 minute at a temperature of 80 ° C. using a hot plate to form a film having a thickness of 0.25 μm on the silicon wafer. Then, an electron beam drawing device (ELS3300 manufactured by Elionix Co., Ltd.) is used to draw a number of evaluation figures on the sample under a condition of an accelerating voltage of 20 KV while changing the exposure amount. The exposed sample is baked after exposure for 2 minutes at a temperature of 160 ° C. using a hot plate. Then, this sample was 2.38% (2.38 g / 100 ml)
Is developed for 30 seconds with an aqueous tetramethylammonium hydroxide solution, and rinsed with pure water for 30 seconds. This allows
A resist pattern was obtained in which the electron beam non-irradiated portion of the film was dissolved in the developing solution.

Next, the remaining film thickness after development is measured by a Taly step (a film thickness meter manufactured by Rank Taylor Hobson Co.). A curve, which is a value obtained by normalizing the value with the initial film thickness, is plotted against the logarithm of the exposure amount, that is, a characteristic curve is created.
As a result, the sensitivity and contrast were determined to be 15 μC / cm ² and 3.0, respectively. Further, when the resist pattern was observed with a scanning electron microscope (SEM), it was found that a line and space of 0.5 μm was resolved. The exposure dose required to obtain this pattern was 20 μC / cm ² .

4. O ₂ -RIE Resistance A thermosetting resist layer having a thickness of 2 μm is formed as a lower layer on a silicon wafer. Next, the resist solution of the example is applied onto this lower layer by spin coating. Next, this silicon wafer is heated to 80 ° C. using a hot plate.
Pre-baking is performed at a temperature of 1 minute for 1 minute to form a film having a thickness of 0.25 μm as an upper layer made of the composition of the example.
Then, this film is exposed to an electron beam according to the procedure of the above-mentioned patterning experiment, baked after exposure, developed and rinsed.

The obtained sample was used as DEM45 manufactured by Nichiden Anelva.
Oxygen gas flow rate 50s using dry etcher called 1
Oxygen plasma etching is performed for 40 minutes under the conditions of ccm, RF power density of 0.12 W / cm ² and gas pressure of 1.3 Pa.

This plasma-etched sample is SEM
As a result of the observation, it was found that a 0.5 μm line-and-space pattern having a thickness of about 2 μm was formed in a substantially vertical shape. The exposure dose for obtaining such a pattern was 20 μC / cm ² .

Although the examples of the radiation-sensitive resin composition of the present invention have been described above, the present invention is not limited to these examples.

For example, even when the acid generator is a suitable one other than those used in the examples, such as those represented by the above formulas (I) to (VII), the above-mentioned examples are also applicable. The same effect as can be obtained.

Further, in the above-mentioned examples, the radiation-sensitive resin composition was exposed using an electron beam as the radiation. However, the radiation used for this exposure is not limited to the electron beam, but may be light or X-ray. Alternatively, the same effect as in the embodiment can be obtained by using other radiation such as an ion beam.

[0051]

As is apparent from the above description, according to the radiation-sensitive resin composition of the present invention, when the radiation-sensitive resin composition is selectively irradiated with the radiation, the radiation-irradiated portion is crosslinked by cationic polymerization, and the radiation-sensitive resin composition is also exposed. In the non-irradiated part, Claisen rearrangement occurs by applying an appropriate amount of heat to the composition, so that phenol soluble in an aqueous alkali solution is produced. Therefore, a negative type pattern can be formed with the alkaline aqueous solution.

Further, since the crosslinking of the poly (siloxane) as the first component at the irradiated portion is caused by the action of a small amount of acid from the acid generator as the second component, the radiation-sensitive resin composition concerned. Since the exposure amount at the time of exposing the composition will be an exposure amount capable of generating a desired (catalytic amount) acid from the acid generator, the composition becomes highly sensitive.

Further, since poly (siloxane) as the first component has a silicon-oxygen bond in the main chain, it is efficiently converted into silicon dioxide during the process of treatment with oxygen plasma, so that dry etching resistance is also secured. It

Therefore, it is highly sensitive to radiation and O ₂
-Because it is possible to provide a radiation-sensitive resin composition having excellent RIE resistance, for example, shortening of exposure time in the manufacture of semiconductor devices,
High-precision etching processing becomes possible.

Further, when this composition is used as the upper layer resist in the two-layer resist method, the composition can be developed by an alkaline aqueous solution, so that the lower layer is adversely affected as compared with the case where an organic solvent is used as the developing solution. Less is.
Further, since it is not necessary to use an organic solvent, it is possible to obtain the effects of reducing adverse effects on the human body and environment and saving resources.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03F 7/029 7/038 505 7/26 511 7124-2H H01L 21/027

Claims (5)

[Claims] 1. A radiation-sensitive resin composition comprising a poly (siloxane) represented by the following formula (1) and an acid generator that decomposes to generate an acid by the action of irradiation radiation. (However, n is the degree of polymerization.). [Chemical 1] 2. The sulfonium salt is used as the acid generator, and its addition amount is 0.0 based on the weight of the poly (siloxane) used.
The radiation-sensitive resin composition according to claim 1, which is 1 to 50%. 3. The iodonium salt is used as the acid generator, and the addition amount thereof is 0.0 based on the weight of the poly (siloxane) used.
The radiation-sensitive resin composition according to claim 1, which is 1 to 50%. 4. The acid generator is an aromatic compound having at least one trichloromethyl group, and the addition amount thereof is 0.01 to 50% with respect to the weight of poly (siloxane) used. Item 2. The radiation-sensitive resin composition according to item 1. 5. The p-toluenesulfonate as the acid generator, and the addition amount thereof is 0.01 to 50% with respect to the weight of the poly (siloxane) used.
The radiation-sensitive resin composition described.