JP2989064B2 - Pattern forming method of metal deposition film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a negative photosensitive composition
Relates the pattern forming method of the vapor-deposited metal film used, more particularly, a semiconductor integrated circuit, pattern of the photomask, Oite the pattern formation such as flat panel displays, the metal deposited film with a negative photosensitive resist of an alkali development type
And a method of forming the pattern.

[0002] The negative photosensitive composition used in the present invention comprises:
In order to form a reverse tapered (including overhanging) resist pattern, a lift-off (lift-o
It is suitable for a pattern forming method by the ff) method.

[0003]

2. Description of the Related Art As a photoresist (etching resist) used for forming a pattern on a substrate by wet etching or dry etching, various photosensitive compositions are known, both positive type and negative type. But,
At present, suitable photoresists for forming a pattern by the lift-off method (lift-off resists) are not always known.

In the lift-off method, a resist film on a substrate is first exposed in a pattern, developed, and then a metal is deposited on the substrate having the obtained resist pattern. Thereafter, if the resist portion is peeled off, a pattern of the metal vapor deposition film remains on the substrate. By the way, when a metal is deposited on a substrate having a resist pattern, a deposited film is formed on the resist pattern and on the substrate.
If the cross-sectional shape of the resist pattern is an overhang shape or a reverse taper shape, the deposited film formed on the substrate is
This is preferable because the resist pattern and the deposited film formed thereon are deposited independently of each other.

However, conventionally, there are few suitable photoresist materials capable of forming such a resist pattern for lift-off. Therefore, the processing steps of the etching resist are devised to form an overhang-shaped resist pattern, and the lift-off method is performed. For pattern formation.

For example, when a positive photoresist composed of a novolak resin and a quinonediazide compound is used as a lift-off resist, the resist film is treated with an organic solvent after exposure and before development to dissolve the surface of the resist film in a developing solution. There is known a method of forming an overhang resist pattern by lowering the speed. However, in this method, since the upper part of the resist pattern overhangs thinly like a eaves, the evaporative part deposited on the resist pattern sags, and short-circuits with the evaporative film formed on the substrate. Problem. In addition, since the entire resist film before development is hardly dissolved in the developing solution, there is a problem that the development speed tends to be uneven depending on the location.

[0007]

The purpose of the 0008] The present invention relates to a semiconductor integrated circuit, the photomask, a lift-off method using Oite the pattern formation such as flat panel displays, an alkali development type negative photosensitive composition Metal deposition film
An object of the present invention is to provide a method for forming a good pattern .

The inventors of the present invention have conducted intensive studies to solve the above-mentioned drawbacks of the prior art. As a result, they have found that a component which crosslinks by exposure to light or exposure and subsequent heat treatment, an alkali-soluble resin, and a compound which absorbs the exposure light. It has been found that, when a negative photosensitive composition containing at least one of the following is used as a developing solution, an alkaline aqueous solution can be used to form an overhang-like or reverse-tapered resist pattern particularly suitable for a lift-off method.

The negative photosensitive composition can be used as a normal etching resist because the shape of the resist pattern can be changed to a forward tapered shape by adjusting the exposure amount. The present invention has been completed based on these findings.

[0010]

According to the present invention, there is provided:
IfAfter exposing the resist film on the substrate in a pattern,
Image and then the resulting substrate with resist pattern
Metal is deposited on the top, and then the resist pattern is removed.
In the method of forming a pattern of a metal deposition film to be removed, (A) As a resist for forming a resist film,
 (A)Light that generates radicals by irradiation with actinic rays
A polymerization initiator and an unsaturated carbonized polymerizable by the radical.
Combination with a compound having a hydrogen group, or active light
A compound that generates an acid by irradiation with a ray,
Consisting of a combination with a crosslinking compound,Dew due to light rays
Cross-linking by light or exposure and subsequent heat treatment
Minutes, (B) an alkali-soluble resin, and (C)Azo dyeing
Material having (substituted) benzaldehyde and active methylene group
Styrene derivative obtained by condensation of
Dyes, arylbenzotriazoles, azomethine dyes
Food, curcumin, and xanthone
At least oneCompound that absorbs light for exposureTo
containsNegative photosensitive compositionUse (B) Adjust the amount of exposure to make the registration
Strike pattern, and (C) Use an aqueous alkaline solution as a developer for development.
Forming a pattern of a metal deposited film characterized by using
 Is provided.

Hereinafter, the present invention will be described in detail. The negative photosensitive composition of the present invention comprises the following three components (A) to
(C) is contained as an essential component. Component (A): a compound that crosslinks alone or with another compound upon exposure to light, or generates a catalyst for a crosslinking reaction or the like upon exposure and crosslinks with the compound itself or another compound through heat treatment after exposure. Compound or compound group. Component (B): soluble in a developer which is an aqueous alkaline solution,
And a resinous component substantially insoluble in water. Component (C): a component that absorbs exposure light involved in the crosslinking reaction of component (A).

The negative photosensitive composition of the present invention is used by coating it on a substrate in the form of a film. For this purpose, the composition is dissolved in an organic solvent to form a solution or is applied as a uniform powder. And the remaining solvent is dried if necessary. The substrate having a resist film made of the negative photosensitive composition thus obtained is exposed to a pattern by a conventional method, and is developed and used.

As a light source for exposure, mainly ultraviolet rays are used. After exposure in a pattern, heat treatment (post-exposure bake) is performed as it is or after exposure, and then an alkaline aqueous solution of an inorganic or organic compound is developed. And develop. After development, a negative pattern is formed on the substrate.

<Component (A)> As the component (A) of the negative photosensitive composition of the present invention, (1) a photopolymerization initiator which generates a radical upon irradiation with an actinic ray and a non-polymerizable initiator which is polymerized by the radical. A combination of a compound having a saturated hydrocarbon group and, if necessary, a sensitizer for increasing the efficiency of the photoreaction can be given.

Examples of the photopolymerization initiator include benzophenone derivatives, benzoin and benzoin ether derivatives. For these, it is necessary to select a conjugate system from the aspect of spectral sensitivity according to the wavelength of the light source for exposing the pattern, but the structure is not particularly limited.

As the compound having an unsaturated hydrocarbon group, (meth) acrylates, in particular, a polyfunctional compound having a plurality of (meth) acrylic acid residues are preferable.
It is preferable that the compound having a polyfunctional unsaturated hydrocarbon group has a certain degree of solubility in an alkaline aqueous solution as a developing solution, since the residue after development is reduced.

As the component (A), in addition to the above, a combination of (2) a compound capable of generating an acid upon irradiation with actinic rays (hereinafter abbreviated as "acid generator") and a compound capable of crosslinking by the acid can be mentioned. Can be

Examples of the compound that generates an acid by actinic light include aromatic sulfonates, aromatic iodonium salts, aromatic sulfonium salts, and aromatic compounds having an alkyl halide residue. These are preferably selected from the viewpoint of spectral sensitivity as in the case of the photopolymerization initiator described above.

Examples of the compound which is crosslinked by the acid generated from the acid generator include melamine-formaldehyde resin, alkyl etherified melamine resin, benzoguanamine resin, alkyl etherified benzoguanamine resin,
Examples include urea resins, alkyl etherified urea resins, urethane-formaldehyde resins, resole-type phenol formaldehyde resins, alkyl etherified resole-type phenol formaldehyde resins, and epoxy resins.

The proportion of the component (A) is not particularly limited, but is usually 0.1 to 20 parts by weight, preferably 0.5 to 20 parts by weight, per 100 parts by weight of the alkali-soluble resin of the component (B).
Use in the range of 5 parts by weight.

<Component (B)> The component (B) of the negative photosensitive composition of the present invention is a phenolic resin obtained by reacting a compound having a phenolic hydroxyl group with an aldehyde in the presence of an acid or alkali. Examples thereof include novolak resins obtained by addition-condensation of phenol or alkylphenol and formaldehyde with oxalic acid, and resole-type phenol resins obtained by subjecting similar raw materials to addition reaction or partial condensation under alkaline or neutral conditions.

Examples of the addition-polymerized polymer of an unsaturated alkyl group-substituted phenol compound include, for example, poly (p-vinylphenol), poly (p-isopropenylphenol), and homopolymers or copolymers of isomers of these monomers. Polymers.

Further, as a homo- or copolymer of unsaturated carboxylic acid or unsaturated carboxylic acid anhydride, (meth) acrylic acid, maleic acid, itaconic acid, etc., and the addition of these anhydrides and unsaturated hydrocarbons Polymeric polymers are mentioned. Natural resins such as rosin and shellac can also be used.

<Component (C)> As the component (C) of the negative-working photosensitive composition of the present invention, a compound having an absorption region in the wavelength region according to the wavelength of the light source for exposure is selected. Good.

However, in the case where the solubility is low in an aqueous alkali solution as a developing solution, it is liable to remain on the substrate after development, so that an acidic residue such as a phenolic hydroxyl group, a carboxy group or a sulfonyl group is imparted to the aqueous solution to give an alkali. Those with increased solubility in aqueous solutions are preferred. In order to solve the problem of generation of residues, it is preferable to select a compound having a higher absorbance so that a sufficient absorbance can be obtained with a small amount of addition. When the formed resist pattern is exposed to a high temperature in a post-baking or sputtering step, the compound may sublime and contaminate the apparatus, and therefore, a compound having a low sublimability is preferable.

The component (C) of the present invention includes so-called azo dyes, for example, azobenzene derivatives, azonaphthalene derivatives, azobenzene or azonaphthalene-substituted arylpyrrolidone, and complex compounds such as pyrazolone, benzopyrazolone, pyrazole, imidazole and thiazole. And a ring arylazo compound.

In these arylazo compounds, the length and the substituent of the conjugated system are appropriately selected in order to set the absorption wavelength in a desired region. For example, sulfonic acid (metal salt) group, sulfonic acid ester group, sulfone group, carboxy group,
By substituting with an electron-withdrawing group such as a cyano group, a (substituted) aryl or alkylcarbonyl group, or a halogen, an absorption region can be set at a short wavelength. Further, the absorption wavelength may be set to a long wavelength region by an electron donating group such as an amino group, a hydroxy group, an alkoxy group, or an aryloxy group substituted by a (substituted) alkyl, (substituted) aryl or polyoxyalkylene group. it can.

As the substituent, there are a group which lowers the solubility in alkali such as an amino group and a group which increases the solubility in alkali such as a carboxy group and a hydroxy group. It is desirable to appropriately select such that the sensitivity of the object becomes a practical level.

In the case of azo dyes, various compounds can be used in a wide wavelength range of 200 to 500 nm by selecting the structure of the compound. Such selection of the length of the conjugated system and the substituents also applies to compounds other than the azo dye.

As a compound mainly corresponding to a light source of the order of 300 to 400 nm, a styrene derivative obtained by condensing (substituted) benzaldehyde with a compound having an active methylene group can be mentioned. Examples of the substituent of benzaldehyde include a (hydroxy, alkoxy or halo) alkylamino group, a polyoxyalkyleneamino group, a hydroxy group, a halogen, an alkyl group, an alkoxy group, an alkyl and an arylcarbonyl group. As the compound having an active methylene group, for example, acetonitrile, α-
Examples include 1,3-diketones such as cyanoacetate, α-cyanoketones, malonate and acetoacetate.

It is also possible to use methine dyes and arylbenzotriazoles obtained by condensing arylpyrazolone and arylaldehyde, azomethine dyes obtained as condensates of amine and aldehyde, and natural compounds such as curcumin and xanthone. .

Further, the development characteristics are adjusted by using a compound which changes the solubility in alkali while simultaneously absorbing exposure light, such as a quinonediazidosulfonic acid ester of a dye having an arylhydroxy group or a bisazide compound, or a crosslinking reaction. Is also good.

The proportion of the component (C) used in the present invention is optimal depending on the film thickness in which the photosensitive composition of the present invention is used. Good. Component (C) is generally used in an amount of 0.1 to 15 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the alkali-soluble resin of component (B).

<Negative photosensitive composition> The negative photosensitive composition of the present invention may be used as a powder, but usually, the above components (A) to (C) are uniformly dissolved in a solvent. , Filtered and used. The solid content in the solution is usually about 10 to 40% by weight.

Examples of the solvent include alcohols such as propanol and butanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone;
Acetates such as ethyl acetate, butyl acetate, and isoamyl acetate; cyclic ethers such as tetrahydrofuran and dioxane; methyl cellosolve, ethyl cellosolve, butyl cellosolve, and the like; further, ethyl cellosolve acetate, butyl cellosolve acetate, γ-butyrolactone, propylene glycol monomethyl ether acetate; Examples include ethyl lactate, ethyl ethoxypropionate, and ethyl pyruvate.

An additive such as a surfactant can be added to the negative photosensitive composition of the present invention, if desired.

In the method of using the negative photosensitive composition of the present invention, first, the composition is uniformly coated on a substrate by spin coating or the like.
Heat treatment at 80 to 110 ° C. to form a dry film of 0.5 to several μm. Next, pattern exposure is performed using a desired light source. When the negative photosensitive composition of the present invention comprises an unsaturated carboxylic acid copolymer, a photopolymerization initiator, a polyfunctional (meth) acrylate and a light-absorbing compound, it can be developed as it is. In the case of a system containing a compound that generates an acid by light and a compound that crosslinks with the acid, 100 to 1 after exposure for the purpose of accelerating the crosslinking reaction.
After a heat treatment of about 30 ° C. (post-exposure bake: hereinafter abbreviated as “PEB”), development is performed.

As a light source for exposure, 436 nm, 40
A mercury emission line spectrum of 5 nm, 365 nm, 254 nm or the like, a KrF excimer laser light source of 248 nm, or the like can be used.

In the negative type composition of the present invention, the exposed portion crosslinks and acts on the negative type, so that when the exposure amount exceeds a certain amount, the resist film starts to remain after development. This exposure energy is called Eth. A resist pattern having a cross-sectional shape of an overhang or a reverse taper is usually obtained with an exposure amount of about twice or less of Eth. When the exposure amount is further increased, a resist pattern having a forward taper shape instead of an overhang shape or a reverse taper shape is obtained, so that it can be subjected to a normal etching method.

[0040]

The present invention will be described more specifically below with reference to examples and comparative examples. Parts and% in Examples and Comparative Examples are based on weight unless otherwise specified.

Example 1 The composition ratio of methacrylic acid: methyl methacrylate was 20:
80 parts, 100 parts of methacrylic acid-methyl methacrylate copolymer having a weight average molecular weight of 30,000, 6 parts of pentaerythritol tetraacrylate, Michler's ketone 2
Part, and 4- (4-dimethylaminophenylazo)-
Dissolve 2 parts of phenol in 330 parts of a mixed solvent of ethyl cellosolve acetate / ethyl cellosolve = 60/40,
The solution was filtered through a 0.22 μm membrane filter to prepare a negative photosensitive composition solution.

The above composition was spin-coated on a silicon single crystal wafer substrate and prebaked on a hot plate at 90 ° C. for 60 seconds to obtain a wafer having a resist film having a thickness of 1.5 μm. The illuminance ratio of g-line / i-line was 7 /
The sensitivity was measured by exposing through a step tablet using a PLA501F contact exposure apparatus in a state of 5 (mW / cm ² ). When paddle development was performed with a 0.5% NaOH aqueous solution for 60 seconds, the sensitivity was 87 mJ / cm ² .

In the same manner, the wafer on which the resist film having a thickness of 1.5 μm was formed was subjected to a sensitivity through a mask for evaluating resolution.
(Eth) was exposed from 0.2 to 2.6 times the sensitivity in increments of 0.2. Development was the same as for the sensitivity measurement.
The wafer was cracked, and the cross section of the pattern was observed with a scanning electron microscope. Exposure amount is 1.4 to 2.0 times the sensitivity (Eth)
In the double range, the edges of all the patterns having a size of 3 μm line and space or more had an inversely tapered shape. The surface alone did not become heissed.

The aluminum wiring forming procedure by the lift-off method was applied to the wafer having the resist pattern formed as described above as follows. Illuminance at 254 nm is 1.
After irradiating the resist pattern with a high pressure mercury lamp of ² mW / cm ² for 200 seconds to harden the resist pattern, aluminum is vacuum deposited by placing the wafer on a hot plate set at 200 ° C. with the resist pattern side up, and about 4000 ° C. A deposited film having a film thickness of? Next, the vacuum-deposited wafer is
The wafer was shaken in dimethyl sulfoxide heated to 0 ° C., washed with isopropyl alcohol and dried to remove the resist pattern.

As a result of observing the state of the resist pattern in a vacuum-deposited state and the state after peeling by an electron microscope, there was no wraparound of aluminum under the reverse tapered portion of the edge of the resist pattern, and there was no deformation of the reverse taper. Was. The pattern formed by the aluminum vapor-deposited film after the resist pattern was stripped had no short circuit or disconnection, and no edge pattern on the aluminum pattern was observed.

[Example 2] Novolak resin 100 having a weight average molecular weight of 5200, which was addition-condensed with formaldehyde in the preparation of m-cresol / p-cresol = 60/40.
Parts, 10 parts of hexamethoxymethylated melamine, 2- (4
-Methoxynaphthyl) -4,6-bis (trichloromethyl) -S-triazine (3 parts), 4- (4-dimethylaminophenylazo) -phenol (2 parts), and a compound having the following structure (1 part) were treated with ethyl cellosolve acetate 300. The mixture was dissolved in the mixture and filtered through a membrane filter to prepare a photosensitive composition.

[0047]

Embedded image

As an exposure apparatus, an NSR1755i7A type i-line stepper (illuminance: 500 mW / cm ² ) was used.
At the time of sensitivity measurement, exposure was performed through a quartz plate while changing the exposure amount. After the exposure, sensitivity measurement and pattern formation were performed in the same manner as in Example 1 except that post-exposure baking was performed on a hot plate at 110 ° C. for 90 seconds, and paddle development was performed with a 2.38% aqueous solution of tetramethylammonium hydroxide for 60 seconds. went. Sensitivity is 30mJ / cm ²
1.5 μm in the range of 1.2 to 2.0 times (Eth)
In all the patterns over the line and space, the edges became reverse tapered , and no scissors were observed.

The aluminum lift-off procedure was applied to the wafer having the above resist pattern in the same manner as in the first embodiment. There was no deformation of the resist pattern and no wraparound of aluminum under the reverse taper. Further, the aluminum pattern after the resist pattern was peeled did not have any disconnection, short-circuit, roundness or the like.

[Comparative Example 1] Novolak resin 100 having a weight average molecular weight of 9800, which was addition-condensed with formaldehyde in the preparation of m-cresol / p-cresol = 60/40.
And 2,3,4-trihydroxybenzophenone and o-naphthoquinonediazide-5-sulfonic acid chloride in an amount of 20 parts of an esterified product dissolved in 360 parts of ethyl cellosolve acetate, filtered and subjected to a positive working photo. A resist was prepared.

The resist was spin-coated on a single-crystal silicon wafer substrate and baked on a hot plate at 100 ° C. for 60 seconds to obtain a wafer having a 1.5 μm-thick resist film. This wafer was treated with xylene / ethyl acetate = 1
After immersing in a solvent having a weight ratio of / 1 at room temperature for 30 seconds, it was dried.
Sensitivity measurement and pattern formation were performed in the same manner as in Example 1 except that 2.38% tetramethylammonium hydroxide was used as a developer.

The sensitivity was 60 mJ / cm ² . The resist pattern is resolved at a dose of 1.8 times or more for a size of 2 μm line and space or more.
A 3000 cm thick eaves was formed. But,
The lower part of the Hisashi had a swell, and the tip did not reach the bottom edge of the resist pattern.

Aluminum lift-off was performed on the above-described wafer in the same procedure as in Example 1. In the resist pattern after vapor deposition, the eaves hang down, and in some places, the aluminum vapor deposited film deposited on the resist pattern was connected to the aluminum vapor deposited film on the substrate. After the resist pattern was peeled off, portions that could not be peeled off due to the connection between the aluminum vapor-deposited films and the aluminum pattern were observed.

[0054]

According to the present invention, a Ri <br/> developable by an alkaline aqueous solution, a good reverse tapered (overhanging
The resist pattern ) and lift-off method
A pattern that can form a good metallized film pattern.
A method for forming a turn is provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/306 H01L 21/306 N (72) Inventor Hiromi Kanai 1-2-1 Yoko, Kawasaki-ku, Kawasaki-shi, Kanagawa Pref. (56) References JP-A-58-42040 (JP, A) JP-A-64-28362 (JP, A) JP-A-64-54441 (JP, A) JP-A-1-164937 (JP, A) JP-A-1-124842 (JP, A) JP-A-2-296245 (JP, A) JP-A-4-151665 (JP, A) JP-A-59-142538 (JP, A) Kaihei 2-275453 (JP, A) JP-B 62-44258 (JP, B2) European publication 436174 (EP, A2)

Claims (2)

(57) [Claims] (1)Exposure of resist film on substrate in pattern
After developing, then the obtained resist pattern
A metal is deposited on the substrate having the
In the pattern formation method of the metal deposition film to remove the turn
hand, (A) As a resist for forming a resist film,
 (A)Light that generates radicals by irradiation with actinic rays
A polymerization initiator and an unsaturated carbonized polymerizable by the radical.
Combination with a compound having a hydrogen group, or active light
A compound that generates an acid by irradiation with a ray,
Consisting of a combination with a crosslinking compound,Dew due to light rays
Cross-linking by light or exposure and subsequent heat treatment
Minutes, (B) an alkali-soluble resin, and (C)Azo dyeing
Material having (substituted) benzaldehyde and active methylene group
Styrene derivative obtained by condensation of
Dyes, arylbenzotriazoles, azomethine dyes
Food, curcumin, and xanthone
At least oneCompound that absorbs light for exposureTo
containsNegative photosensitive compositionUse (B) Adjust the amount of exposure to make the registration
Strike pattern, and (C) Use an aqueous alkaline solution as a developer for development.
Pattern formation method of metallized film characterized by using
Law. 2. The component (B) is added to 100 parts by weight of the component
(A) is 0.1 to 20 parts by weight, and component (C) is 0.1
The metal vapor according to claim 1, which is used in each proportion of from 15 to 15 parts by weight.
A method for forming a pattern for deposition.