JPH0367257B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for forming a fine pattern using a photosensitive resin composition that has excellent developability with an alkaline aqueous solution and forms a positive image. With the rapid progress of the semiconductor industry in recent years, there has been a demand for wide-ranging improvements in functionality and properties in resist materials used in patterning semiconductor elements. In response to these demands, various types of photosensitive resin compositions have been put into practical use, and although each of them has its own characteristics, it also has many drawbacks. Among these photosensitive resins that have been put to practical use, photosensitive resin compositions containing aromatic azide compounds and novolac resins or polyhydroxystyrene resins as main components (for example, Japanese Patent Publication No. 1983-34902) use alkaline aqueous solutions. A major feature of this method is that it is possible to perform development at low temperatures. Many photosensitive resin compositions are known that use organic solvents as developing solutions, but in these cases, the pattern formed by development absorbs the solvent and swells, resulting in poor resolution, especially in the case of highly integrated semiconductor devices. This has been a major problem from the viewpoint of forming the fine patterns necessary for In addition, when an organic solvent is used as a developing solution, there are other problems such as countermeasures against harmful solvent vapor, treatment of large amounts of organic waste liquid, and conservation of petroleum resources, and improvements have been desired. In the developing method using an alkaline aqueous solution, the main component of the solution is water, so the formed resin pattern does not swell. For this reason, the photosensitive resin composition has excellent microfabricability, and is attracting attention as an effective method in terms of safety, health, and resource conservation. There is. However, these photosensitive resin compositions also have problems mainly due to the properties of the azide compound used as a photosensitizer. In the systems currently in use, the azide compounds used are in most cases highly crystalline solids, and when made into a solution, they precipitate out of the solution, and when made into a coating film, they precipitate out from the film. There were times when I did. A particular disadvantage is that during aqueous alkaline development, these crystals remain in the form of fine particles in the unexposed areas that are dissolved. Such residual development not only adversely affects post-processing after pattern formation, but also causes smearing between patterns or pattern cutting, making it impossible to use especially when high resolution is required. As a result, the characteristics of aqueous solution development cannot be utilized. For this reason, improved methods have been attempted to remove these by physical means such as spray development, but this is insufficient for semiconductor devices where even a single defect can result in a defective product. There are many aspects to this, and a more effective method has been desired, especially from the viewpoint of improving yield. An object of the present invention is to eliminate the drawbacks of the above-mentioned conventional techniques and to provide a pattern forming method with excellent microfabrication processability. In order to achieve the above objective, as a result of intensive studies focusing on improving the aromatic azide compound component of the photosensitive resin composition, it was found that if an aromatic azide compound that is in a liquid state at room temperature is used, microprocessability during pattern formation is improved. was found to be significantly improved. Here, liquid at room temperature means liquid at least at one point within the temperature range of 5 to 30°C. A method for removing fine aromatic azide compound particles found in unexposed areas that dissolve during development is as follows:
A method of cleaning with an organic solvent that dissolves these may be considered, but in this case, the pattern formed in the exposed area would also be dissolved, which is not appropriate. Another method is to make the aromatic azide compound itself into a liquid, which is a fundamental solution since the fine particle component is an aromatic azide compound. The difficulty in putting this method into practice lies in selecting an aromatic azide compound that is liquid and highly photosensitive. Therefore, as a result of synthesizing various aromatic azide compounds and examining their physical properties and photosensitivity, we found that the general formula (1) (However, -N ₃ is located at the meta or para position with respect to -X-R-Y, and X is

【formula】

【formula】

【formula】

One group selected from [Formula], R is -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ -, -
CH ₂ CH ₂ OCH ₂ CH ₂ CH ₂ −,

One group selected from [Formula], Y is -OH, _-NH2 , -N( _CH3 ) ₂ , -N
Represents one group selected from ( _C2H5 ) _{2 and} -N _{( C3H7} ) ₂ . ) is an aromatic azide compound represented by
It has been found that when combined with an alkali-soluble polymer, it has high photosensitivity and is liquid at room temperature. Using the photosensitive resin composition containing this liquid aromatic azide compound as one of its components, the pattern developed using an alkaline aqueous solution has a dissolving unexposed area that is similar to that when conventional crystalline aromatic azide is used. Phenomena such as fine particle precipitation and development residue were not observed, and the pattern was clean, and pattern defects were significantly reduced. Hereinafter, the photosensitive resin composition used in the fine pattern forming method of the present invention will be explained in more detail. Examples of the alkali-soluble polymer compound of the photosensitive resin composition used in the pattern forming method of the present invention include novolak resin (here, meaning a condensate of formaldehyde and carbolic acid, cresol, and other alkylphenols) or polyhydroxystyrene resin. etc. can be mentioned. Novolac resins can be used in the form of homocondensates or cocondensates, and polyhydroxystyrene resins can also be used in the form of homopolymers or copolymers (hereinafter, novolac resins, polyhydroxy (Wrap with styrene resin.) These may be used alone or in the form of a mixture of the two. Novolac resins and polyhydroxystyrene resins can also be obtained as commercial products. for example,
Examples of novolac resins include carbolic acid novolac resins, cresol novolac resins, and carbolic acid/cresol novolac resins, and examples of polyhydroxystyrene resins include poly-P-vinylphenol. The molecular weight, cocondensation composition ratio, and copolymerization composition ratio of these base resins can be arbitrarily changed depending on the purpose. The base resin used needs to be formed into a film at the temperature used as a photoresist, for example 10 to 100°C, and for this reason, the number average molecular weight is preferably 500 or more, preferably 1000 or more.
500,000 or less, preferably 1,000 or more and 100,000 or less. A major feature of the aromatic azide compound of the photosensitive resin composition used in the pattern forming method of the present invention is that it is liquid at room temperature. An example of an aromatic azide compound that has sufficient photosensitivity and is liquid when combined with an alkali-soluble polymer is para(or meta)azidobenzoic acid 2-(N,
N-dimethylamino)ethyl, para (or meta)
Azidobenzoic acid 3-(N,N-dimethylamino)
Propyl, para (or meta)azidobenzoic acid 2-
Benzoic acid ester aromatic azide compounds such as hydroxyethyl, N,N-dimethyl-N'-para(or meta)azidobenzoylethylenediamine,
Benzoic acid amide aromatic azide compounds such as N,N-dimethyl-N'-para (or meta)azidobezoylpropylene diamine, para (or meta)
Azidocinnamic acid 2-(N,N-dimethylamino)
Ethyl, para (or meta)azidocinnamic acid 3-
Cinnamate ester aromatic azide compounds such as (N,N-dimethylamino)propyl, N,N-diethylamino-N'-para(or meta)azidobenzylideneacetylethylenediamine, N,N-
Cinnamic acid amide aromatic azide compounds such as dimethylamino-N'-para(or meta)azidobenzylideneacetylpropylene diamine, para(or meta)azido-α-cyanocinnamic acid 2-(N,
N-dimethylamino)ethyl, para (or meta)
Examples include aromatic azide compounds based on α-cyanocinnamate such as 3-(N,N-dimethylamino)propyl azide-α-cyanocinnamate. The above aromatic azide compound is synthesized, for example, by the method shown below. The benzoic acid ester aromatic azide compound is composed of azide benzoic acid chloride and N,
N-dialkylaminoalkanol is reacted to produce a hydrochloride of a benzoic acid ester aromatic azide compound. Next, by treating this with sodium hydroxide, the desired aromatic azide compound can be obtained. Similarly, benzoic acid amide-based aromatic azide compounds can be used to obtain the hydrochloride of the target compound by reacting the corresponding aromatic azide-based acid chloride compound with N,N-dialkylaminoalkylene diamine. It can be synthesized by treatment with an alkali such as sodium hydroxide. Among benzoic acid ester-based aromatic azide compounds, compounds with a hydroxyl group at one end of the molecule, such as 2-hydroxyethyl azidebenzoate, can be used to convert aromatic azide-based acid chloride compounds into organic compounds such as pyridine and triethylamine. It is obtained by reacting with a large excess of alkylene diol in the presence of a base. The blending ratio of the alkali-soluble polymer compound and the aromatic azide compound that is in a liquid state at room temperature in the photosensitive resin composition used in the pattern forming method of the present invention is based on the aromatic azide compound when the alkali-soluble polymer compound is 100 parts by weight. The azide compound is preferably used in an amount of 0.5 parts by weight to 150 parts by weight, more preferably 2 parts by weight to 100 parts by weight. If the amount is less than this range, the photosensitivity may not be sufficient for practical use, and if the amount is more than this range, the film forming ability may deteriorate significantly. many. The photosensitive resin composition used in the pattern forming method of the present invention is applied to the surface of a suitable substrate in the form of a solution dissolved in a suitable organic solvent. Therefore, the solvent used must be capable of dissolving all of the components of the photosensitive resin composition, and includes ketone types such as acetone, methyl ethyl ketone, and cyclohexanone, cellosolve types such as methyl cellosolve, ethyl cellosolve, and ethyl cellosolve acetate, ethyl acetate, Solvents such as esters such as butyl acetate can be used for these purposes. These may be used alone or in a mixed system of two or more types, as long as each component is soluble. The proportion of the solvent to be used is preferably within the range of 100 parts by weight to 10,000 parts by weight, and more preferably, when the total amount of the alkali-soluble polymer and aromatic azide compound is 100 parts by weight. It is preferably used in a range of 200 parts by weight to 5000 parts by weight. In addition to an alkali-soluble polymer, an aromatic azide compound that is in a liquid state at room temperature, and a solvent, the photosensitive resin composition used in the pattern forming method of the present invention may further contain secondary components depending on the purpose. I don't mind. Examples of these include thermal polymerization inhibitors to measure storage stability, surfactants to improve "wettability" with the substrate, antihalation agents to prevent halation from the substrate, and Adhesion improvers, dyes, pigments, fillers, flame retardants, sensitizers, etc. for improving adhesion may be used. Next, each pattern forming process will be explained individually. As a method for applying the photosensitive resin composition to the support substrate, methods such as rotational application using a spinner, dipping, spraying, and printing can be selected depending on the purpose. These are then dried at an appropriate temperature (below 120°C, preferably 70-100°C) to form a film. The coating film thickness can be adjusted by the coating means, the solid content concentration of the solution, and the viscosity. A relief pattern can be obtained by irradiating the photosensitive resin composition formed into a coating film on a supporting substrate with ultraviolet rays in places, and then dissolving and removing the unexposed portions with a developer. The irradiation source is not limited to ultraviolet rays, but may also be radiation such as X-rays and electron beams. The optimal irradiation dose required for sensitization varies depending on the composition, but is 5 to 500 mJ/cm ² for ultraviolet rays, 10 to 500 mJ/cm ² for X-rays, and 1 × 10 ^-6 for electron beams.
It is desirable to irradiate by selecting an appropriate amount from the range of ~5×10 ⁻⁵ C/cm ² depending on the purpose. The photosensitive resin composition used in the present invention can be developed with an alkaline solution as described above. Examples of these include aqueous solutions of tetraalkylammonium hydroxide such as tetramethylammonium hydroxide, inorganic alkaline aqueous solutions such as tribasic sodium phosphate, and sodium hydroxide; However, it is not limited to these. Development can be carried out by a dipping method, a spray developing method, or the like. The desired temperature range for development is 5-60℃.
℃, but since the development rate depends on the temperature conditions, it is desirable to select it depending on the purpose. Even if a liquid aromatic azide compound is used, if the component ratio increases, development will occur in which these substances adhere to the substrate surface. As a result, patterns can be formed extremely cleanly and with a high yield. After development, a rinsing treatment is performed to remove the developer from the substrate and clean the surface of the substrate, and water is preferably used as the rinsing agent for this purpose. In addition, organic solvents may be used as long as they have good miscibility with the developer and do not dissolve the formed pattern. Examples of these include, but are not limited to, ethanol, isopropyl alcohol, and the like. Furthermore, a mixture of water and an organic solvent may be used. The treatment can be carried out by dipping, spraying, etc. The present invention will be explained below by way of examples. still,
Parts in the examples indicate parts by weight. Example 1 10 parts of carbolic acid novolak resin was added to cyclohexanone.
A solution of the photosensitive resin composition was prepared by dissolving 90 parts of the photosensitive resin composition and then dissolving 1 part of 2-hydroxyethyl paraazidobenzoate. At this time, paraazidobenzoic acid 2-
Hydroxyethyl instantly dissolved to form a homogeneous solution. Next, this solution was filtered under pressure using a filter with 1 mμ pores. The obtained solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to form a 0.8 μm layer.
A thick coating film was obtained. This coating film was closely covered with a striped quartz photomask and irradiated with ultraviolet light for 5 seconds from a distance of 30 cm using a 500 W Xe-Hg lamp.
Spray development was performed using a 0.15N potassium hydroxide aqueous solution, and then washing was performed with water to obtain a sharp edge relief pattern. The pattern is clean, with no crystal precipitation images seen when crystalline aromatic azide compounds are used, and no development residue between patterns due to this component. I was able to transcribe it. Example 2 A solution of a photosensitive resin composition was prepared by dissolving 10 parts of cresol novolac resin in 120 parts of ethyl cellosolve acetate, and then dissolving 2 parts of 2-(N,N-dimethylamino)ethyl paraazidobenzoate. did. At this time, paraazidobenzoic acid 2-(N,N-
Dimethylamino)ethyl instantly dissolved to become a homogeneous solution. This solution was then filtered under pressure using a 1 μm pore filter. The obtained solution was spin-coated onto a ceramic substrate using a spinner, and then dried at 70°C for 20 minutes to form a 0.8 μm layer.
A thick coating film was obtained. This coating film was closely covered with a striped quartz photomask and irradiated with ultraviolet light for 5 seconds from a distance of 30 cm using a 500 W Xe-Hg lamp.
Spray development was performed using a 0.2N aqueous sodium hydroxide solution, and then washing was performed with water to obtain a sharp relief pattern on the end surface. The pattern was sufficiently clean as shown in Example 1. Example 3 A solution of a photosensitive resin composition was prepared by dissolving 10 parts of polyparavinylphenol in 120 parts of ethyl cellosolve acetate, and then dissolving with 3 parts of 3-(N,N-dimethylamino)propyl metaazidobenzoate. did. As shown in Example 1, the aromatic azide component dissolved instantly upon addition in this case as well. This solution was then filtered under pressure using a 1 μm pore filter. The obtained liquid was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to obtain a coating film with a thickness of 0.9 μm. This coating film was closely covered with a striped quartz photomask and irradiated with ultraviolet light for 5 seconds from a distance of 30 cm using a 500 W Xe-Hg lamp. 0.2
Spray development was performed using a specified aqueous solution of tetramethylammonium hydroxide, followed by washing with water to obtain a sharp relief pattern on the edge surface. The pattern was sufficiently clean as seen in Example 1. Example 4 A solution of a photosensitive resin composition was prepared by dissolving 10 parts of carbolic acid novolac resin in 40 parts of methyl cellosolve acetate, and then dissolving 3 parts of N,N-dimethyl-N'-paraazidobenzoylethylenediamine. As seen in Example 1, the aromatic azide component dissolved instantly upon addition. This solution was then filtered under pressure using a 1 μm pore filter. The obtained solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to form a 0.9 μm layer.
A thick coating film was obtained. This coating film was closely covered with a striped quartz photomask and irradiated with ultraviolet light for 5 seconds from a distance of 30 cm using a 500 W Xe-Hg lamp.
Spray development was performed using an aqueous solution of 0.2N tetramethylammonium hydroxide, followed by washing with water to obtain a sharp relief pattern on the edge surface. The pattern was sufficiently clean as seen in Example 1. Example 5 A solution of a photosensitive resin composition was prepared by dissolving 10 parts of carbolic acid novolac resin in 100 parts of methyl cellosolve acetate, and then dissolving 3 parts of 2-(N,N-dimethylamino)ethyl paraazidocinnamate. .
When the aromatic azide component was added, it instantly dissolved to become a homogeneous solution. Next, this solution was filtered under pressure using a filter with 1 μm pores. The obtained solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to form a 1.0 μm layer.
A thick coating film was obtained. This coating film was closely covered with a striped soda glass photomask and irradiated with ultraviolet light for 10 seconds from a distance of 30 cm using a 500 W high-pressure mercury lamp. Spray development was performed using an aqueous solution of 0.2N tetramethylammonium hydroxide, followed by washing with water to obtain a sharp relief pattern on the edge surface. The pattern was clean enough to be comparable to that seen in Example 1. Example 6 A solution of a photosensitive resin composition was prepared by dissolving 10 parts of carbolic acid novolak resin in 100 parts of methyl cellosolve acetate, and then dissolving 4 parts of N,N-diethylamino-N'-paraazidobenzylideneacetylethylenediamine. . When added, the aromatic azide component instantly dissolved to form a homogeneous solution. Next, this solution was filtered under pressure using a filter with 1 μm pores. The obtained liquid was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to obtain a coating film with a thickness of 1.1 μm. This coating film was closely covered with a striped soda glass photomask and irradiated with ultraviolet light for 10 seconds from a distance of 30 cm using a 500 W high-pressure mercury lamp. Developed by immersion method using an aqueous solution of 0.2N tetramethylammonium hydroxide,
Next, wash with water to create sharp reliefs on the edges.
I got the pattern. The pattern was clean enough to be comparable to that seen in Example 1. Example 7 10 parts of polyparavinylphenol was dissolved in 100 parts of methyl cellosolve acetate, and then 3 parts of 2-(N,N-dimethylamino)ethyl paraazide α-cyanocinnamate was dissolved to prepare a photosensitive resin composition. A solution was prepared. When added, the aromatic azide component instantly dissolved to form a homogeneous solution. Next, add this solution to
Pressure was applied using a filter with 1 μm pores. The obtained liquid was spin-coated onto a silicon wafer using a spinner, and then dried at 70° C. for 20 minutes to obtain a coating film of 0.9 μm. This coating film was closely covered with a striped soda glass photomask and irradiated with ultraviolet light for 10 seconds from a distance of 30 cm using a 500 W high-pressure mercury lamp. Developed by immersion method using an aqueous solution of 0.2N tetramethylammonium hydroxide,
Next, wash with water to create sharp reliefs on the edges.
I got the pattern. The pattern was clean enough to be comparable to that seen in Example 1. Example 8 A solution of a photosensitive resin composition was prepared by dissolving 10 parts of polyparavinylphenol resin in 100 parts of ethyl cellosolve acetate, and then dissolving 0.5 part of 2-hydroxyethyl paraazidobenzoate. When added, the aromatic azide component instantly dissolved to form a homogeneous solution. Next, this solution was filtered under pressure using a filter with 1 μm pores. The obtained solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to form a 0.7 μm layer.
A coating film was obtained. This coating film was closely covered with a striped quartz photomask and irradiated with ultraviolet light for 15 seconds from a distance of 30 cm using a 500 W high-pressure mercury lamp. 0.2
Spray development was performed using a specified aqueous solution of tetramethylammonium hydroxide, followed by washing with water to obtain a sharp relief pattern on the edge surface.
The pattern was clean enough to be comparable to that seen in Example 1. Comparative Example 10 parts of carbolic acid novolac resin was dissolved in 40 parts of methyl cellosolve acetate, and then 1 part of 4,4'-diazide acetophenone, a crystalline azide compound, was added as a fine powder and stirred at room temperature for 10 hours. However, the azide compound was not completely dissolved. Furthermore, the liquid was heated to 50°C in order to dissolve the azide compound, but it did not completely dissolve. This liquid was then pressurized using a 1 μm pore filter. The obtained solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to form a 0.9 μm layer.
A coating film was obtained. This coating film was closely covered with a striped quartz photomask and irradiated with ultraviolet light for 15 seconds from a distance of 30 cm using a 500 W Xe-Hg lamp. 0.2
A relief pattern was obtained by spray development using a specified aqueous solution of tetramethylammonium hydroxide and subsequent washing with water. In the unexposed areas washed away by the developer, fine particles of the azide compound can be seen everywhere, especially fine particles of 1 to 3 μm.
In the m-wide line and space pattern, there were many parts where the lines were spaced by crystals of the azide compound. As described in detail above, the fine pattern forming method of the present invention can solve the problem of forming fine patterns using a conventional photosensitive resin composition consisting of an alkali-soluble polymer and an aromatic azide compound. Developability with aqueous solutions was significantly improved. The fine pattern forming method of the present invention is particularly excellent in terms of pattern resolution, and is useful for forming patterns of highly integrated semiconductors.

Claims (1)

[Claims] 1 General formula (1) in a liquid state on a substrate at room temperature (However, -N ₃ is located at the meta or para position with respect to -X-R-Y, X is one group selected from [Formula] [Formula] [Formula] [Formula], R is -CH ₂ CH ₂ −, −
CH ₂ CH ₂ CH ₂ −, −CH ₂ CH ₂ OCH ₂ CH ₂ CH ₂ −, one group selected from [Formula], Y is −OH, −NH ₂ , −N(CH ₃ ) ₂ , − N
Represents one group selected _from ( _C2H5 ) ₂ and _-N ( _C3H7 ) ₂ . ), a homo-condensed novolac resin, a co-condensed novolac resin,
A photosensitive resin composition consisting of at least one alkali-soluble polymer compound selected from polyhydroxystyrene homopolymer and polyhydroxystyrene copolymer and a solvent is applied and dried to form a photosensitive resin film. A method for forming a fine pattern, which is characterized in that the film is formed, locally exposed to light, and then developed with an alkaline aqueous solution to dissolve and remove unexposed areas.