JPH0262544A - Photoresist composition - Google Patents

Abstract

PURPOSE:To obtain the positive type photoresist compsn. adequate for lithography using deep UV rays and excimer laser as a light source by constituting the compsn. of a prescribed polymer and a compd. which generates an acid by active rays. CONSTITUTION:The polymer has the resin having an ether group as a resin component and having excellent transparency and has the structure expressed by formula. R1, R3 denote 1 to 5C alkyl groups; R2 is 1 to 10C alkyl group; 0.1<=m/(m+n)<=1. A photoacid generating agent such as diphenyl ethane deriv. which efficiently generates the acid by irradiation of deep UV rays and excimer laser light is used as the photosensitive component. Sufficient exposing of the exposed part of the resist down to the bottom is enabled by this constitution and the C-O bond of the essential component resin is cloven by the generated acid and heat to create the -OH group and to increase the alkaline solubility of the resin. As a result, a large difference is generated in the solubility with the unexposed part and the sensitivity, definition and development latitude of the resist are improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a photoresist composition suitable for forming a fine resist pattern, and more specifically, a photoresist composition suitable for forming a fine resist pattern. The present invention relates to a positive photoresist composition that has high sensitivity and high resolution, and also has excellent alkaline development tolerance. The photoresist composition of the present invention can be applied to LIS or ultra-LS.
In addition to being used to create high-density integrated circuits such as I, it can also be used to manufacture photomasks used in their manufacture, and is widely used in the field of electronic industry.

[Prior Art] In recent years, semiconductors have become increasingly highly integrated, and the demands for miniaturization are becoming more and more severe.

Therefore, in terms of manufacturing, it is becoming difficult to cope with conventional processes, and the introduction of new technologies is being considered. Efforts are being made to establish ultra-fine pattern processing technology by using deep ultraviolet rays with shorter wavelengths and excimer lasers instead of conventional ultraviolet rays as light sources used in lithography. Resist compositions used as excimer laser lithography resists include, for example, compositions whose main component is a resin that decomposes upon irradiation with actinic rays, such as polymethyl methacrylate or polymethyl glutarimide, and compositions such as Talesol. A composition has been proposed in which a naphthoquinonediazide sulfonic acid ester derivative is mixed as a photosensitizer with an alkali-soluble resin such as formaldehyde novolac resin.

However, although resist compositions containing the above-mentioned photodegradable resin as a main component have excellent resolution, they have poor sensitivity in the deep ultraviolet and excimer laser wavelength regions, and also have insufficient RIE resistance. There were some problems. Furthermore, although resist compositions using the naphthoquinonediazide sulfonic acid ester derivatives described above as photosensitizers have excellent sensitivity and RIE resistance, the naphthoquinonediazide sulfonic acid ester derivatives have poor absorption in the deep ultraviolet and excimer laser wavelength regions. Since it does not decrease after exposure, no matter what type of alkali-soluble resin is used as the main component, the surface layer of the resist will absorb light strongly, and the bottom of the resist will not be exposed sufficiently, resulting in the desired rectangular shape. The drawback was that it was difficult to obtain a resist pattern with a profile of .

[Problems to be Solved by the Invention] As described above, conventional photoresist compositions have poor sensitivity, resolution, and
There is no one that can satisfy all the requirements such as RIE resistance, and it is still difficult to say that it is practical.

Therefore, the present invention has been made to solve the above-mentioned problems. That is, an object of the present invention is to provide a positive photoresist composition that has high sensitivity and resolution for lithography using deep ultraviolet rays and excimer laser as a light source, and also has excellent alkaline development tolerance. It's about doing.

[Means for Solving the Problems] In view of the above circumstances, the present inventors have made extensive studies and have developed a highly transparent resin having an ether group as a resin component, and a deep ultraviolet and excimer as a photosensitive component. laser
By using a photoacid generator that can efficiently generate acid when irradiated with light, it is possible to fully expose the exposed part of the resist to the bottom, and the acid and heat generated in this exposed part can be used to The C-O bond of the resin, which is the main component, is cleaved to generate -OH groups,
The alkali solubility of the resin can be increased.

As a result, we have discovered that it is possible to create a large difference in alkali solubility between the exposed and unexposed areas, and as a result, the sensitivity, resolution, and development tolerance of the resist can be improved. I was able to complete it.

That is, the present invention provides a polymer represented by the following general formula (1) (wherein R, R3 is a hydrogen atom or a group selected from an alkyl group having 1 to 5 carbon atoms, and R2 is a group having 1 to 10 carbon atoms). represents a group selected from alkyl groups, Q, l ≦m/ (
m+n)≦1. ) and a compound capable of generating an acid upon irradiation with actinic rays. The photoresist composition of the present invention will be explained in detail below.

In the photoresist composition of the present invention, the C-0 bond of the resin having an ether bond is cleaved by heat treatment in the presence of an acid to generate an -OH group, resulting in increased alkali solubility. Although heat treatment is not necessarily necessary, −
It is desirable to perform this for the purpose of promoting the production of 011 groups.

The lower limit of the proportion of structural units having ether bonds in the resin is desirably 10% or more of the total structural units of the resin. If this ratio is less than 10%, it will adversely affect the developability of the resist. The upper limit of the ratio is not limited and can be determined within a range that does not adversely affect the alkali solubility of the resin and the development characteristics of the resist.

Such a resin having an ether bond can be produced by radical polymerization or ionic polymerization of alkoxystyrene. Further, it can be produced by radical copolymerization or ionic copolymerization of alkoxystyrene and hydroxystyrene. Specific examples of these resins include, but are not limited to, those shown below.

In addition, the resin was determined by the gel permeation chroma+ method (GPC method) using polystyrene as a standard.
a average molecule it (MW) is 2. rJu~to.

000 preferably 3,000 to 20. Use NO. If the above range is exceeded, the sensitivity, resolution, heat resistance,
This has an adverse effect on film performance and adhesion to the substrate.

Next, the compounds used as photosensitive components in the photoresist composition of the present invention are those that generate acids when irradiated with deep ultraviolet rays, excimer laser, etc., and many of these compounds are generally widely known.

Examples of such compounds include halogenated diphenylethane derivatives represented by the following general formula (n), sulfonic acid ester derivatives represented by the following general formula (m), and iodonium salts represented by the following general formula (IV). Alternatively, sulfonium salts represented by the following general formula (V) may be mentioned.

R9-0502-RIO (■) Each of the atoms R, , R, is a hydrogen atom, a halogen atom, or an alkyl group.

The sulfonic acid ester derivative represented by the general formula (III) above generates sulfonic acid upon irradiation with actinic rays, and R9 in the formula is a group that blocks the hydrogen site of the sulfonic acid. As such a group, the halogenated diphenylethane derivative represented by the above general formula (II) produces a halogen acid upon irradiation with actinic rays, and R4 in the formula is a hydrogen atom, a halogen atom, or an alkyl group. , alkoxy group, hydroxyl group, or nitro group, R6 is a hydrogen atom, hydroxyl group, or R
+s CON H- (R1, is an alkyl group.)
, Ro is a halogen (RIt is an alkylene group, alkenylene group, or arylene group, R, , R, , R,, SR
, and R28 are each an alkyl group or an aryl group,
R2,,R,.

is an aryl group, and R2 and R2 are each a hydrogen atom, an alkyl group, or an aryl group. ) can be mentioned. Moreover, R8o is an alkyl group or an aryl group.

The iodonium salt represented by the above general formula (IV) and the sulfonium salt represented by the above general formula (V) produce a Lewis acid upon irradiation with actinic rays, and R1 in the formula
1, R1□, RI3 and R14 are aryl groups, Rls is an alkyl group or aryl group, X is BF, -PF, -As
F, -5bF6C1o, -.

Specific examples of such photoacid generators include Ga-N
H-0-5OzGCH co(]IF-3) (III-4) (m-5) (m-6) (n-1) (n-2) (n-
3) (m-1) (m-2) (IV-1
) (IV-2) (V-1) (V-2), etc., but are not limited to these. Further, these photoacid generator agents can be used alone or in combination of two or more.

The content of the photoacid generator in the present invention is desirably 0.01 to 20 parts by weight, preferably 0.05 to 1 part by weight, per 100 parts by weight of the resin.

If the content is too large, pattern accuracy will be adversely affected.

The photoresist composition according to the present invention is soluble in organic solvents, and when used in the fabrication of integrated circuits, it is usually used in solutions (
It is used in the form of a resist solution). In this case, the composition is generally 1 to 50% by weight, preferably 5 to 3%, in an organic solvent.
It is dissolved and adjusted at a ratio of 0% by weight. In this case, the solvent to be used is such that each constituent component of the negative photoresist composition of the present invention is uniformly dissolved, and the organic solvent is evaporated after coating on the surface of a substrate such as silicon or aluminum. It is preferable that a smooth coating film be obtained. Specifically, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl cellosolve, ethyl cellosolve, butyl cellosolve,
Examples include, but are not limited to, cellosolve solvents such as methyl cellosolve acetate and ethyl cellosolve acetate, ether solvents such as tetrahydrofuran and diethylene glycol dimethyl ether, and ester solvents such as ethylene glycol monoethyl ester and ethylene glycol monomethyl acetate. The above organic solvents may be used alone or in combination of two or more.

In addition to the above-mentioned components, the photoresist composition of the present invention may optionally contain sensitizing columns, dyes, plasticizers, other resins, various inhibitors such as thermal reaction inhibitors, adhesion improvers, etc. I can do it.

With the negative photoresist composition of the present invention, a relief pattern can be formed by conventional photoresist techniques by adjusting the resist solution as described above. The method for forming this relief pattern will be explained below.

First, a resist solution prepared as described above is applied to a substrate. This application to the substrate can be performed using, for example, a spinner. This is then heated to a temperature of 60-120°C, preferably 80-120°C.
Dry at 100°C for 20-60 minutes. After drying, the coated film is irradiated with deep ultraviolet rays and excimer laser through a positive photomask chart.

Next, the substrate is heat-treated at a temperature of 120° C. or lower using a hot plate or the like.

Thereafter, a relief pattern is obtained by washing out the exposed area with a developer. As the developer, a weak alkaline aqueous solution of sodium hydroxide, potassium hydroxide, sodium metasilicate, tetramethylammonium hydroxide, etc., having a concentration of 5% by weight or less, can be used. The resist pattern thus formed has good resolution and contrast.

Furthermore, a substrate can be etched using the photoresist composition of the present invention and the pattern formed as described above as a mask.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

(Production Example 1) p-terl-butoxysitylene 2G and azobisisobutyronitrile (AIRN
)0.5g and tetrahydrofuran (THF) 40m
Added l. Thereafter, the flask was cooled to -70°C, degassed under vacuum, and replaced with argon. After repeating this operation three times in total, the reaction was carried out at 75° C. for 20 hours. After the reaction was completed, the reaction mixture was poured into 1,000 ml of methanol to obtain a polymer. The obtained polymer was diluted with acetone-methanol system.
Purification was carried out by repeated precipitation to obtain 13 g of polymer. The weight average molecular weight of the polymer was 8.500 as determined by gel permeation chromatography (CPC).

(Production Example 2) 15 g of p-isopropoxystyrene, 5 g of p-hydroxystyrene, 0.4 g of azobisisobutyronitrile (AIBN), and 40 ml of tetrahydrofuran (THF) were added to a 700 ml eggplant-shaped flask. Thereafter, the flask was cooled to -70°C, degassed under vacuum, and replaced with argon. After repeating this operation three times in total, the reaction was carried out at 75° C. for 20 hours. After the reaction is completed, 1.000ml of the reaction mixture is
of methanol to obtain a copolymer.

The obtained copolymer was purified by precipitation twice using an acetone-methanol system to obtain 12 g of a copolymer. The weight average molecular weight of the copolymer was determined by gel permeation chromatography (G
It was 7,300 from PC) measurement.

The proportion of alkoxy in the copolymer was 70% according to 'H-NMR.

(Example 1) 3 g of the polymer obtained in Production Example 1 and 0.13 g of 1,1-bis(p-chlorophenyl)-2゜22-trichloroethane as a photoacid generator were mixed with 13i of cyclohexanone.
This solution was filtered under pressure using a 0.2 μm pore filter to prepare a resist solution. This resist solution was coated onto a silicon wafer using a spin coater at 2.800 rpm, and prebater was performed at 80° C. for 40 minutes to obtain a coating film of 1.0 μm.

Next, this resist film was subjected to 115 reduction projection exposure using a +F excimer laser stepper. After heat-treating the exposed silicon wafer at 100°C for 60 seconds on a hot plate, it was immersed in a 2.3% tetramethylammonium hydroxide aqueous solution for 60 seconds for development, and then rinsed by immersing it in water for 30 seconds. A sensitivity curve was obtained by plotting the film against the exposure amount, and the exposure amount at which the remaining film after development was O was defined as the sensitivity. The sensitivity of this resist was 73 m1/cJl.

Furthermore, using this resist, in the same manner as above, a resist film with a thickness of 1.0 μm was formed on a silicon wafer, and through a chrome mask having a pattern, 115 reduction projection exposure was performed using a KrF excimer laser stepper. . Furthermore, this resist film was diluted with a 2.3% aqueous solution of tetramethylammonium hydroxide (20°C) for 60°C.
A resist pattern was formed by developing for seconds and washing with water for 30 seconds. As a result of observing the pattern thus formed using an electron microscope, it was found that a fine pattern of 0.75 μm with a good profile was resolved.

(Example 2) Results obtained in the same manner as in Example 1 except that α-tosyloxydeoxybenzoin was used instead of 1,1-bis(p-chlorophenyl)-2,2,2-)lichloroethane. , a sensitivity of 87 mi/crl was obtained. In addition, as a result of observing the formed pattern with an electron microscope,
It was found that a fine pattern of 0.75 μm with a good profile was resolved.

(Example 3) Using the copolymer obtained in Production Example 2 instead of the polymer in Example 1, 1. The same procedure was performed except that diphenyliodonium tetrafluoroborate was used instead of I-bis (p-chlorophenyl)-2,2,2-trichloroethane, and as a result, a sensitivity of 82 mi/d was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a fine pattern of 0.75 μm with a good profile was resolved.

(Example 4) The same procedure as in Example 3 was performed except that triphenylsulfonium hexafluorophosphate was used instead of diphenyliodonium tetrafluoroborate, and as a result, a sensitivity of 97 m1/cnf was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a fine pattern of 0.75 μm with a good profile was resolved.

[Effects of the Invention] As explained above, the photoresist composition of the present invention not only has excellent sensitivity and resolution when used in lithography using deep ultraviolet rays and excimer laser as a light source, but also has excellent sensitivity and resolution during development. As a result of its excellent tolerability under alkaline development conditions, fine resist patterns with good profiles can be formed.

Is it possible to get a

Claims (1)

[Claims] (1) Polymer represented by the following general formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) (In the formula, R_1 and R_3 are hydrogen atoms or carbon atoms from 1 to 5
R_2 represents a group selected from alkyl groups having 1 to 10 carbon atoms, and 0.1≦m/(m+n)≦1. ) and a compound capable of generating an acid upon irradiation with actinic rays.