FR2842533A1 - Antireflective coating composition used in the production of intricate photoresist patterns, comprises polydimethylsiloxane in addition to crosslinker, crosslinking initiator, light absorbing agent and organic solvent - Google Patents

Abstract

An antireflective organic coating composition comprises a crosslinking agent, a light absorbing agent, a thermally activated acid generator, an organic solvent and a polydimethylsiloxane polymer. Independent claims are also included for: (1) a method of forming a photoresist by applying the claimed composition onto the surface of a layer intended to be attacked, heat treating the resulting material to generate crosslinks and form an anti-reflective organic film, applying a coating of photoresist onto the anti-reflective film, exposing to a source of light and developing; and (2) a semiconductor device fabricated using the claimed method.

Description

The present invention relates to an organic coating composition

  anti-reflective and a method for forming a photoresist pattern using the composition, preventing reflection of a lower film layer or a substrate of a photoresist film and reducing standing waves due to light and variations in the thickness of the photoresist itself, thereby increasing the uniformity of the photoresist pattern in connection with an extremely fine pattern formation process using photoresists for photoengraving using F2 type light having a wavelength of 157 nm, among other methods of manufacturing a semiconductor device. The present invention relates more particularly to an organic anti-reflective coating composition and to a method for forming photoresist patterns using such a composition, making it possible to prevent the absorption capacity of an anti-reflective film from being too high. and, therefore, to minimize the reflective power of the film so that it can effectively eliminate standing waves and increase the uniformity of the photoresist pattern, through the use of specific polymers based on organosilicon in addition to coating compositions

  organic anti-reflection traditionally available.

  It is known that during the extremely fine patterning processes used in the context of conventional semiconductor production methods, standing waves are created resulting from the optical properties of a lower film layer, that is to say say of the substrate of a photoresist film, and / or of a change in thickness of a photosensitive film, of the presence of reflective notches and / or of a variation of a critical dimension (hereinafter called "CD") of the photoresist pattern due to the diffracted light and the light reflected from the substrate. It has therefore been proposed to insert between the substrate and the photoresist a protective layer against reflection created on the substrate, by introducing materials having a very good capacity for absorbing light in the length ranges of wave of exposure light sources, protective layer called an anti-reflective film. This anti-reflective film can, generally, be classified in the category of inorganic anti-reflective films or in the category of organic anti-reflective films according to the types of materials.

used.

  In recent years, organic anti-reflective films have been widely used in extremely fine patterning processes, and their

  compositions must meet the following requirements.

  (1) After applying the anti-reflective film in layers and during the process of applying the photoresist over the film, it should not dissolve in a solvent of the photoresist. This is the reason why it is necessary that the film is designed to develop cross-linked structures during its application in a layer, the process consisting in applying the film in coating, then in carrying out a baking treatment while preventing production. other materials

  chemicals as by-products.

  (2) To prevent scattered reflection from the substrate, the film must contain certain materials to absorb light within the range of

  wavelengths of the exposure light source.

  (3) The method of applying the anti-reflective coating composition in a layer requires a particular catalyst to activate the crosslinking reaction. To meet the above requirements, conventional anti-reflective organic coating compositions generally include a cross-linking agent allowing the anti-reflective film to exhibit the required cross-linked structure, a light absorbing agent for absorbing light within the length range of the exposure light source, and a thermal acid generator like

  catalyst to activate the crosslinking reaction.

  However, it should be noted that although the organic anti-reflective film preferably requires a high absorbance since it must absorb light and serve to prevent the reflection of light on the substrate, as has been described above, the absorbance of light is not always proportional to reflectance. On the contrary, an excessively high absorbance of light can lead to a decrease in the amount of light penetrating through the anti-reflective film and lead to an increase in the reflectance of the latter, which makes it difficult to effectively reduce standing waves and the of a photoresist pattern

quality.

  Therefore, the absorbance of the organic anti-reflective film is preferably in the range of 0.3 to 0.6. However, most of the organic materials generally present in conventional anti-reflective organic coating compositions have an absorbance greater than 0.7 with respect to the light source F2 having a wavelength of 157 nm. Consequently, it is considered that the organic anti-reflective film formed using these known compositions has too high an absorbance with respect to this light, so that in the case of the extremely fine pattern formation method using the light F2 of wavelength 157 nm, standing waves cannot be reduced, which does not allow

  to obtain quality photoresist patterns.

  In view of the above problems with existing compositions, there is a need for improved anti-reflective organic coating compositions to effectively eliminate standing waves and to achieve stable photoresist patterns during the extremely fine patterning process at using an F2 type light source having a

157 nm wavelength.

  The present invention specifically aims to provide an organic anti-reflective coating composition which is capable of preventing the absorption of an anti-reflective film from being too high so that the latter can effectively eliminate standing waves, and which allows forming quality photoresist patterns using specific organosilicon polymers in addition to organic anti-reflective coating compositions

traditionally used.

  Another object of the present invention is to provide a photoresist patterning method comprising the use of the organic anti-reflective coating composition, which makes it possible to obtain a perpendicular photoresist pattern in an extremely fine patterning process.

  using a 157 nm F2 type light source.

  To achieve the above goals and according to a first aspect of the present invention, there is provided an organic anti-reflective coating composition, characterized in that it comprises a crosslinking agent for providing an anti-reflective film with a crosslinked structure; a light absorbing agent, which has a high absorbance in a wavelength range of an exposure light source; a thermal acid generator; an organic solvent; and a polymeric compound, such as a polydimethylsiloxane having a structure according to the following formula 1 and preferably a molecular weight in the range of 14,000

  at 21,000 (average molecular weight).

  (Formula 1) 1H3 CH3 Polydimethylsiloxane polymer which has a low absorbance of 0.1 or less against light having a wavelength of 157 nm can be added to the organic anti-reflective coating composition; therefore, the resulting anti-reflective coating composition has a preferable light absorbance range of 0.3 to 0.6 and minimizes the reflectance of the obtained anti-reflective film. The composition also includes a crosslinking agent or the like having an absorbance of not less than 0.7 in the case of 157 nm light, so that it effectively eliminates standing waves and forms patterns of

satisfactory photoresist.

  As described above, the polydimethylsiloxane polymer included in the coating composition according to the present invention has a molecular weight of 14,000 to 21,000, which corresponds to the characteristic molecular weight for the polymer (see Merck Index, twelfth edition, pages 544 and 545) An embodiment of the organic anti-reflective coating composition according to the present invention may contain materials present in conventional anti-reflective coating compositions, such as the light absorbing agent, preferably a polyvinylphenol polymer having a structure according to the following formula 2. This polyvinylphenol polymer which has a high absorbance to light having a wavelength of 157 nm and which contains hydroxyl groups to react with the crosslinking agent contained in the anti-reflective coating composition to generate a crosslinking bond is well known. and is present in these coating compositions as a light absorbing agent, so that the crosslinking bond makes it possible to protect the anti-reflective film formed against dissolution in the solvent

used for photoresist.

  (Formula 2) Alternatively, the crosslinking agent included in the coating composition of the present invention may, in general, include materials used in conventional anti-reflective organic coating compositions, preferably compounds based on acetal and more preferably polymers having a structure according to the following formula 3. These polymers have a molecular weight in a range of 3,000 to 100,000, generally suitable for a crosslinking polymer

applied to the composition.

(Formula 3) Rl

R. O OR2

  wherein R1 and R2 are each independently a substituted, branched and / or straight chain C1-C10 alkyl group; and R3 is hydrogen or methyl. Acetal-based compounds, such as the polymer of formula 3 above, react with a polyvinylphenol used as a light-absorbing agent and containing hydroxyl groups capable of creating crosslinking by the reaction of an alcohol in the presence of acid, to produce the crosslinking bond so that the organic anti-reflective film formed does not dissolve in the solvent of the photoresist due to this crosslinking bond. This polymer can be obtained by polymerizing (meth) acrylic aldehydes to prepare poly [(meth) acrylic aldehydes), then reacting the resulting materials with substituted, branched chain and / or main C1-Cl6 alkyl alcohol. . This polymer and its practical preparation have been described in Korean patent application No. 99-61343 (published before examination on July 5, 2001) and in Korean patent application No. 99-61344 (published before examination on July 5, 2001), all two filed on December 23, 1999 by the

filing this application.

  For the coating composition of the present invention, described above, the thermal acid generator can generally include conventional thermal acid generators, more preferably 2-hydroxycyclohexyl p-toluenesulfonate which has a structure according to the following formula 4 (Formula 4)

1

  As described above, the thermal acid generator is a catalyst intended to activate the crosslinking reaction between the

  crosslinking and the light absorbing agent.

  The organic anti-reflective film which does not dissolve in the solvent of the photoresist can be formed firstly by the application in coating of this thermal acid generator on the wafer of the device and / or of the semiconductor element. , then by carrying out a heat treatment, such as cooking, to generate an acid from the thermal acid generator and, consequently, induce the crosslinking reaction described above in the presence

of the resulting acid.

  With respect to the anti-reflective organic coating composition of the present invention, the polyvinylphenol polymer of formula 1 used as the light absorbing agent is preferably contained in an amount of 50 to 400% by weight based on the total amount of the crosslinking agent included in the present composition, while the thermal acid generator is preferably contained in an amount of 10 to 200% by weight relative to the amount of the crosslinking agent. In addition, the organic solvent is preferably contained in an amount of 1,000 to 10,000% by weight based on the total amount of the crosslinking agent and the light absorbing agent included in the present composition. For its part, the polydimethylsiloxane is preferably present in an amount of 20 to 100% by weight relative to the total amount of the crosslinking agent and the light absorbing agent included.

in the composition.

  Thanks to these respective components having the compositions indicated above, the anti-reflective organic coating composition of the present invention can provide effective protection against scattered reflection from the bottom film layer, that is to say from the substrate. of the photoresist film, while preventing lateral attack on the lower part of the components of the crosslinking reaction, thereby allowing quality perpendicular photoresist patterns to be obtained. In addition, thanks to the fact that the composition contains polymethylsiloxane in the proportion indicated above, the anti-reflective film formed can have an optimal absorbance of light having a wavelength of 157 nm, suitable for effectively eliminating standing waves due to the reflection of the substrate. In another embodiment of the present invention, the organic anti-reflective coating composition may further comprise a crown ether compound as an acid diffusion inhibitor, more preferably 18-crown-6 ( 1, 4, 7, 10, 13, 16- hexaoxacyclooctadecane) having a structure according to the following formula 5 (Formula 5) O This crown ether-based compound is a compound having a circular crown-like structure like that represented by formula 5 above, and containing oxygen atoms inside this circular structure. The oxygen atoms contained in this compound are optionally capable of interacting with certain cations, the size of which corresponds to that of the cavity in the central part of the circular structure of the organic solvent. In other words, if the above compound is added to the coating composition of the present invention, it can prevent diffusion of acid towards the lower part of the photoresist and, therefore, lateral attack resulting from this diffusion, even if an acid is generated by the reaction of the developer and polyvinylphenol during the formation of the photoresist pattern, which makes it possible to obtain a pattern of

  quality perpendicular photoresist.

  This acid diffusion inhibitor is preferably contained in an amount of 30 to 500 mol% relative to the amount of the acid generator

  thermal included in the composition.

  According to a second aspect of the present invention, there is provided a method for forming patterns of it photoresist, characterized in that it comprises the steps which consist in applying the organic anti-reflective coating composition of the present invention to the surface of a layer intended to be attacked; subjecting the resulting material to a baking treatment to produce a crosslinking bond and form an anti-reflective organic film; and apply the photoresist as a coating over the anti-reflective film formed, expose the applied film to a light source, then develop the latter to form

  the desired photoresist patterns.

  Since the photoresist pattern forming method of the present invention uses a coating composition containing polydimethylsiloxane, it allows the formed anti-reflective film to have an absorbance of light which is in the range of 0, 3 to 0.6 in the presence of an F2 type light source having a wavelength of 157 nm and to minimize the reflectivity of the film, thereby effectively reducing standing waves. It will therefore be understood that the method of the present invention makes it possible to produce a high quality anti-reflective film suitable for use in an extremely fine pattern formation method using a source of

  light of type F2 having a wavelength of 157 nm.

  An embodiment of the photoresist pattern forming method according to the present invention preferably comprises a baking treatment carried out at a temperature of about 150 to 3000C for 1 to minutes. Under these conditions, an acid is generated by the thermal acid generator to form crosslinking bonds within the anti-reflective film and therefore, to produce the desired anti-reflective film which does not dissolve in the solvent of the photoresist. Furthermore, in accordance with the method of the present invention described above, the baking treatment can also be carried out before and / or after the step of exposing the steps of forming the photoresist pattern and, preferably, in the range of

  temperatures of around 70 to 200 ° C.

  It will be understood that the anti-reflective organic coating composition and the photoresist pattern formation method using it, according to the present invention, can find application in particular extremely fine pattern formation methods using ArF, KrF, ultraviolet radiation. distant (DUV) including EUV (extreme ultraviolet radiation), electron beam, X-rays or ion beams, although they are generally employed in the extremely fine pattern formation process using a source of

type F2 light.

  According to a third aspect of the present invention, there is also provided a semiconductor device produced using the method of forming

  photoresist pattern according to the present invention.

  The present invention will now be described in more detail with reference to examples which are presented by way of illustration only and should not be considered as limiting the

scope of the invention.

  Determination of the absorbance of light of an anti-reflective organic film prepared by the conventional process

COMPARATIVE EXAMPLE 1

  To 13 g of a propylene glycol methyl etheracetate solvent were added and dissolved 0.13 g of a crosslinking agent of formula 6 below, 0.26 g of polyvinylphenol of formula 2 and 0.085 g of a

  thermal acid generator of formula 4 above.

  The resulting mixture was then filtered through a 0.2 µm fine filter to prepare the anti-reflective organic coating composition. The composition obtained was applied by coating by centrifugation on a silicon wafer, baked at 2400C for seconds to generate crosslinking bonds and thus form the desired anti-reflective film. The resulting anti-reflective film was subjected to a determination of light absorbance in the presence of two light sources ArF 193 nm and F2 157 nm. The results of the

  determination are shown in the following Table 1.

(Formula 6) CH30 OCHa

COMPARATIVE EXAMPLE 2

  The procedure of Comparative Example 1 was repeated, except that the amount of polyvinylphenol was 0.13 g instead of 0.26 g. The absorbances of light in the presence of the two light sources (157 nm and 193 nm) have been determined for the film

  resulting and are shown in Table 1.

COMPARATIVE EXAMPLE 3

  The procedure of Comparative Example 1 was repeated, except that the amounts of the crosslinking agent and the polyvinylphenol were 0.26 g and 0.13 g respectively. Likewise, the absorbances of light in the presence of the two light sources (157 nm and 193 nm) were determined for the resulting film and are indicated

in Table 1.

  Table 1 Absorbances of light in the presence of light sources of 157 nm and 193 nm for the anti-reflection film prepared by the conventional method Absorbance Example Example Comparative example 1 comparative 2 comparative 3 Source of 0.89 0.85 0.79 light 157 nm Source of 0.82 0.70 0.48 light 193 nm Determination of the absorbances of light of anti-reflective organic films prepared by means of the present invention

EXAMPLE 1

  To 13 g of a propylene glycol methyl etheracetate solvent were added and dissolved 0.13 g of a crosslinking agent of formula 6, 0.26 g of polyvinylphenol of formula 2, 0.085 g of a generator thermal acid of formula 3 and 0.13 g of polydimethylsiloxane polymer of formula 1 above. The resulting mixture was then filtered through a 0.2 gm fine filter to prepare the organic anti-reflective coating composition. The composition obtained was subjected to a determination of the absorbance of light in the presence of light of 157 nm in accordance with the procedure used in the preceding comparative examples. The results of the

  determination are shown in the following Table 2.

EXAMPLE 2

  The procedure of Example 1 was repeated, except that the amount of polyvinylphenol was 0.13 g instead of 0.26 g. The absorbance of light in the presence of a 157 nm light source was determined for

  the resulting film and is shown in Table 2.

EXAMPLE 3

  The procedure of Example 1 was repeated except that the amounts of the crosslinking agent and the polyvinylphenol were 0, 26 g and 0.13 g, respectively. Likewise, the absorbance of light in the presence of a 157 nm light source was determined for the resulting film and is indicated in

Table 2.

Table 2

  Absorbance of light in the presence of a light source of 157 nm for the anti-reflective film prepared according to the present invention Absorbance Example 1 Example 2 Example 3 Source of 0.54 0.48 0.58 light 157 nm As shown in the examples Comparative 1 to 3 and Examples 1 to 3 above, the anti-reflective film prepared using the conventional method must comprise relative compositions of its crosslinking agent and of its light absorbing agent determined to have absorbances from 0.3 to 0.6, due to the relatively low absorbance of the crosslinking agent in the presence of an ArF type light source (193 nm). However, in the case of the 157 nm light source F2, the crosslinking agent and the light absorbing agent both have an absorbance of 0.7 or more, so that the anti-reflective film has a absorbance too high to be used in a patterning process

  extremely fine using this light source.

  In contrast, the anti-reflective coating composition of the present invention comprises a polydimethylsiloxane polymer having an absorbance of 0.1 or less in the presence of a light source of 157 nm and allows an anti-reflective film having an absorbance in the preferable range to be produced. from 0.3 to 0.6 in the presence of a 157 nm light, the minimum reflectivity of this allowing the coating composition of the present invention to effectively suppress reflection from the film substrate and

  to eliminate standing waves.

  As is clear from the description

  above, the organic anti-reflective coating composition of the present invention may have a preferable absorbance of 0.3 to 0.6 in the presence of a 157nm F2 light source to produce a desirable anti-reflective film having minimum reflectivity in presence of this light, so that the composition makes it possible to effectively remove a reflection from the substrate of the photoresist film and to eliminate standing waves, thereby forming

  quality photoresist patterns.

  In addition, the present invention advantageously makes it possible to produce an excellent anti-reflective organic film which can be used in a process for forming an extremely fine pattern using a F2 light source of 157 nm, a process which is considered to be the main process. of training

photoresist pattern of the future.

  Although the previous description focused on

  different preferred embodiments of the present invention, this is of course not limited to the specific examples described and illustrated here, and those skilled in the art will readily understand that it is possible to make numerous variants and modifications to them.

  without departing from the scope of the invention.

Claims (16)

REVENDI CAT IONS   1. An anti-reflective organic coating composition, characterized in that it comprises a crosslinking agent for providing an anti-reflective film with a crosslinked structure; a light absorbing agent, which has a high absorbance in a wavelength range of an exposure light source; a thermal acid generator; an organic solvent; and a polydimethylsiloxane polymer having a structure according to formula 1 below: (Formula 1) CH3 CH3 2. Composition according to claim 1, characterized in that it comprises, as light-absorbing agent, a polyvinylphenol polymer having a structure according to formula 2 below: (Formula 2) 3. Composition according to claim 1, characterized in that the crosslinking agent comprises polymers having a structure according to the following formula 3, and a molecular weight in a range of 3,000 to 100,000: (Formula 3) R10 OR2   wherein R1 and R2 are each independently a substituted, branched and / or straight chain C1Clo alkyl group; and R3 is hydrogen or methyl. 4. Composition according to claim 1, characterized in that the thermal acid generator comprises 2-hydroxycyclohexyl p-toluenesulfonate having a structure according to formula 4 below: (Formula 4) 5. Composition according to claim 2, characterized in that the polyvinylphenol polymer used as light absorbing agent is contained in an amount of 50 to 400% by weight relative to the amount of the crosslinking agent included in the composition.   6. Composition according to claim 4, characterized in that the thermal acid generator is contained in an amount of 10 to 200% by weight relative to the amount of the crosslinking agent included in the composition.   7. Composition according to claim 1, characterized in that the organic solvent is contained in an amount of 1000 to 10 000% by weight relative to the total amount of the crosslinking agent and the light absorbing agent included in the composition. 8. Composition according to claim 1, characterized in that the polydimethylsiloxane polymer is contained in an amount of 20 to 100% by weight relative to the total amount of the crosslinking agent and of the light absorbing agent included in the composition.   9. Composition according to claim 1, characterized in that it also comprises, as acid diffusion inhibitor, 18couronne-6 (l, 4, 7, 10, 13, 16-hexaoxacyclooctadecane) having a structure according to formula 5 below: (Formula 5) o0 o Q   to 10. Composition according to claim 9, characterized in that the acid diffusion inhibitor is contained in an amount of 30 to 500 mol% relative to the amount of the acid generator   thermal included in the composition.   11. A method of forming a photoresist pattern, characterized in that it comprises the steps which consist in: applying the organic anti-reflective coating composition according to any one of   Claims 1 to 10 on the surface of a layer   intended to be attacked; subjecting the resulting material to a baking treatment to generate crosslinking bonds and to form an anti-reflective organic film; and apply a photoresist coating to the anti-reflective film formed, expose the applied film to a light source, then develop it to form the photoresist pattern.   12. Method according to claim 11, characterized in that the cooking treatment is carried out at a   temperature from 150 to 3000C for 1 to 5 minutes.   13. Method according to claim 11, characterized in that the step of forming the pattern also comprises an additional baking treatment before and / or after the exposure step.   14. Method according to claim 13, characterized in that the cooking treatment is carried out at a temperature from 70 to 2000C.   15. The method of claim 11, characterized in that it is implemented in a process for forming an extremely fine photoresist pattern using F2, ArF, KrF, far ultraviolet radiation (DUV) comprising EWV, a beam   electronics, x-rays or an ion beam.   16. Semiconductor device characterized in that it is manufactured using the process of the claim 11.