JPS6232451A - Developing solution for improved positive type photoresist - Google Patents

Abstract

PURPOSE:To enhance selective solubility of exposed and unexposed parts and to reduce temperature dependency of the solubility of the exposed parts by adding a specified amount of nonionic fluorinated surfactant to a developing solution using an organic base containing no metal ion as an essential agent for use in a positive type photoresist. CONSTITUTION:The nonionic fluorinated surfactant to be added to the developing solution is at least one selected from a group of fluorinated compounds represented by the formula: Rf-A-(CH2CH2O)m-R, embodied by CF3(CF2)7.(CH2 CH2O)10H and the like. It is added in an amount of 50-5,000ppm of the developing solution of the positive type photoresist using an organic base as an essential agent containing no metal ion, thus permitting the developing solution to improve wettability of the photoresist film, and to rise in velocity of spreading on the whole surface of a wafer and to enhance uniformity of development, accordingly, dependency of solubility on temperature to decrease, and allowance of a development process to be enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer for positive-type photoresists, and more specifically, a developer suitable for use in image formation using quinonediazide-based positive-type photoresists. As a result, wettability to the photoresist film is improved, dissolution selectivity between exposed and unexposed areas is improved, development defects do not occur, and the temperature dependence of dissolution in exposed areas is small, making it a good positive type. It relates to a photoresist developer and is useful for manufacturing semiconductor integrated circuit devices.

[Conventional technology]

Conventionally, when manufacturing semiconductor integrated circuit elements, integrated circuit manufacturing masks, printed wiring boards, printing boards, etc., selective processing is performed on the underlying substrate, such as etching or diffusion treatment. At this time, ultraviolet rays,
A film is formed using a composition sensitive to actinic rays such as rays and electron beams, so-called photoresists, and then imagewise exposed.
A method is used in which an image is formed by developing.

There are two types of photoresists: positive type and negative type. In the former type, exposed areas are dissolved by a developer, but unexposed areas are not dissolved, and in the latter type, it is the opposite type. A typical example of the former positive type photoresist is a combination of an alkali-soluble novolac resin as a base and a naphthoquinone diand compound as a photodegrading agent. For this naphthoquinonediazide-based positive photoresist, an alkaline aqueous solution is used as the developer, but when manufacturing semiconductor devices, it is recommended that the product characteristics be improved if an alkaline aqueous solution containing metal ions is used as the developer. Developers that do not contain metal ions, such as tetramethylammonium hydroxide (IBM [Technica
Disclosure Bulletin J Vol. 13, No. 7, Page 2009, 1970) and Colin (
Aqueous solutions such as those disclosed in US Pat. No. 4,239,661 are used.

One of the problems when forming images using positive photoresist is the change in sensitivity due to the temperature of the developer, so-called temperature dependence of the developer, and the line width of the resist image changes significantly depending on the temperature of the developer. Therefore, it is difficult to control the temperature in the static development method and spray development method that are currently widely used. For this reason, it is desired to improve the development properties of a developer with less temperature dependence during development.

By the way, static developing systems are becoming common in developing apparatuses used in the manufacture of semiconductor integrated circuits in order to automate the photoresist process. In this method, a developer is dropped onto the Ueno surface coated with a photoresist film, spread, and then the developer is dropped again after a certain period of time to develop the Ueno while it remains stationary. In this method, the spreading speed of the developer over the entire surface of the wafer is the key to determining the uniformity of the line width of the resist image within the sea urchin.
-The larger the diameter of the -, the more the problem of the developer spreading over the entire surface becomes a problem, and the wettability of the developer becomes more important. In order to improve wettability, JP-A-58-57128 discloses adding 1 to 50% of an organic solvent or surfactant to a positive photoresist such as tetramethylammonium hydroquine. Example t When a hydrophilic solvent such as alcohols or ethylene glycol monoalkyl ethers is added, a relatively small amount will have no effect on wettability, and if a relatively large amount is added, the portions of the resist image that should be left As a result, an image cannot be obtained due to the dissolution of up to 1
Even when a surfactant is used, there is a problem that the developing solution is temperature dependent, and as the temperature rises, the sensitivity increases and the amount of film loss in unexposed areas also increases.

For positive photoresist developers, so-called dissolution selectivity is important, such as completely dissolving exposed areas, hardly dissolving unexposed areas, and not causing any change in film thickness before and after development. , JP-A-58-9143
In the publication, quaternary ammonium type surfactant, JP-A-5
No. 8-150949 discloses the addition of quaternary ammonium salts. Furthermore, in order to increase the contrast of positive photoresists, it is disclosed in JP-A-60-12547 that the developing solution is developed with a solution containing a combination of an alkali metal base and a nonionic fluorine-based surfactant. It goes without saying that not only is it impossible to obtain a stable resist image due to temperature dependence, but also that the use of an alkali metal base is undesirable for manufacturing semiconductor integrated circuit elements, as described above.

[Problem that the invention seeks to solve]

The purpose of the present invention is to solve the above-mentioned problems and to improve the wettability of the Sunawachi photoresist film, which is particularly suitable for image formation using a naphthoquinone diande-based positive photoresist, and to select the dissolution of exposed and non-exposed areas. It is an object of the present invention to provide a positive photoresist developer which can be used for manufacturing semiconductor integrated circuit elements, which has improved properties, does not cause development defects, and has less temperature dependence of dissolution in exposed areas.

[Failure to solve the problem]

As a result of extensive research, the present inventors discovered that the above objective could be achieved by adding a specific fluorine-based surfactant to a conventional positive photoresist developer, and based on this knowledge, As a result, the present invention was completed.

That is, the present invention provides a positive photoresist developer, which is characterized in that 50 to 5000 ppm of a nonionic fluorine-based surfactant is added to a positive photoresist developer whose main ingredient is an organic base that does not contain metal ions. This is what we provide.

The positive photoresist developer of the present invention, which has an organic base as its main ingredient that does not contain metal ions, is one in which only an organic base that does not contain metal ions, which is the main ingredient of the developer, is dissolved in water, and a conventional developer. This includes those containing commonly used additives.

As the metal ion-free organic base constituting the main ingredient of the developer, those conventionally used in this type of developer can be used as appropriate. Examples of such a substituent include linear, branched, or cyclic substituents.

Aryl and alkyl amines, including secondary and tertiary amines, such as alkylene diamines such as 1,3-diaminopropane, aryl amines such as 4,4'-diaminodiphenylamine, bis-(dialkylamino)imines, etc. Amines, 3 to 5 carbon atoms in the ring skeleton and 1 beta atom selected from nitrogen, oxygen and sulfur
or 2 heterocyclic bases, such as pyrrole,
Pyrrolidine, pyrrolidone, pyridine, morpholine, pyrazine, piperidine, oxazole, thiazole, or lower alkyl quaternary ammonium bases are used. Particularly preferred among these are tetramethylammonium hydroxide and trimethyl(2-hydroxyethyl)ammonium hydroxide (choline). Moreover, the above-mentioned organic bases not containing metal ions may be used alone or in combination of two or more.

In addition to wetting agents, stabilizers, and dissolution aids, additives that are commonly used in conventional developing solutions of the present invention include additives that improve the dissolution selectivity between exposed and unexposed areas of a positive photoresist film. These include cationic surfactant and non-surfactant quaternary ammonium compounds, and monohydric alcohols as additives to prevent thin film and scum residues that occur after the development of positive photoresist films. Each can be used alone or in combination.

The nonionic fluorosurfactant added to the developer of the present invention has the general formula n(-A-(CH,Cl-120-E)
-I also [in the formula, Rf is a perfluoroalkyl group having 3 to 5 carbon atoms, and A is a direct bond + CH2moSO, NR, -1
-4-CH2+-0-, (-CH2+-CON Rf-
1-so3-, -co.

and -8o2N(R3)CH, Co2-, where R is a hydrogen atom or has 1 carbon atom.
-18 acyl group or alkyl group, n is 0-2
an integer of 0, m is an integer of 0 to 5, R,, R2, R3 are the same or different hydrogen atoms, an alkyl group having 1 to 6 carbon atoms, or +CI4. CH2O+it, and X is 1 to 20
R4 is an alkyl group having 1 to 6 carbon atoms]
At least one kind selected from the group of fluorine atom-containing compounds represented by, specifically CF3 (CF, ),
・(C11□CFt20)1oH% CF3(CF2
)7So□N(C2H,)(CH,CH,0),4H.

CF, (CF2), SO,N (C,H,) CH
2COO(CH2CH2O), o), 1, CF, (CF
2), -(CF,)3・C0N(CII3)(CH
2 (shiH20), OH, etc., but are not limited thereto.

Further, each of these may be used alone or in combination of two or more.

The amount of nonionic fluorine-based surfactant used in the present invention is in the range of 50 to 5000 ppm to a positive photoresist developer whose main ingredient is an organic base that does not contain metal ions.
It is preferably in the range of 100 to 11000 pi). If it is less than this range, it will become wet and there will be no effect on the properties, and if it exceeds this range, the resulting image shape will lack sharpness, which is undesirable.

[Effect]

Addition of a nonionic fluorine-based surfactant to a positive-type photoresist developer based on an organic base that does not contain metal ions improves the wettability of the developer to the photoresist film, and improves the wetting properties of the developer. It has the effect of improving the spreading speed over the entire surface or the uniformity of development. If a nonionic fluorine-based surfactant was not added, air bubbles would adhere to the surface of the photoresist film, making development impossible or requiring a long time to develop, but with the addition of a surfactant, the developer solution The photoresist film spreads uniformly over the entire surface at an early stage, and air bubbles rise to the surface of the developer, allowing for good development.

Furthermore, the addition of the nonionic fluorine-based surfactant of the present invention reduces temperature changes in the solubility characteristics of a positive photoresist developer whose main ingredient is an organic base that does not contain metal ions, thereby increasing the tolerance of the developing process. do. In particular, in the case of a developer based on tetraalkylammonium hydroxide, a positive photoresist is developed in combination with a novolac resin as a film-forming component and a polyhydroxybenzophenone ester of naphthoquinone diazide-5-sulfonic acid as a photosensitive component. When a fluorine-based surfactant is not added, the solubility is highest when the developer temperature is around 20 to 25°C, and the solubility decreases even if the temperature is higher or lower than this, but the present invention By adding a nonionic fluorosurfactant, this temperature dependence is significantly reduced and the tolerability of the developing process is greatly improved.

Note that when the developer is choline, caustic potash, caustic soda, sodium silicate, etc., the higher the temperature, the higher the sensitivity, and the greater the solubility of the unexposed area. In addition, in the case of a positive photoresist whose photosensitive component is a naphthoquinonediazide sulfonic acid ester of a polyhydroxy compound such as alkyl gallate, novolac resin, or polyhydroxybenzene, the sensitivity is high when the developer temperature is high, and film loss in unexposed areas is reduced. big.

By adding the nonionic fluorosurfactant of the present invention to these positive photoresist developing solutions, the temperature dependence is reduced and the tolerability of the developing process is greatly improved.

The addition of the nonionic fluorine-based surfactant of the present invention acts on a developer based on an organic base that does not contain metal ions, so that the developer spreads uniformly over the photoresist film and improves wettability. It does not lose its activity even under temperature changes.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Examples 1-7. Comparative Examples 1 to 5 2.38'l of tetramethylammonium hydroxide (TMAH) and 4.2 liters of choline as organic bases containing no metal ions were dissolved in water to prepare a positive photoresist developer, and each of these A nonionic fluorine-based surfactant shown in Table 1 was added to prepare a developer for a positive photoresist of the present invention.

For comparison, a sample to which the above surfactant was not added was also prepared.

Spinner (Tatsumo resist coater TR, -40
A positive photoresist OF I) R-5000 (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to a 4-inch silicon wafer using 00) to a film thickness of 1.3 μm.
Prebaking was performed on a hot plate at 110°C for 90 seconds.

After exposure using a DSW4800 reduction projection exposure system (manufactured by GCA) and a test chart manufactured by Dainippon Printing Co., Ltd., static development was performed using the developer prepared above using a homemade static developing device, and pure water was used. After rinsing with water for 30 seconds, the resulting resist pattern on the wafer was observed by drying with nitrogen gas. The results are shown in Table 1. The developer of the present invention was able to develop uniformly within the surface in a short period of time without any dimensional variation, whereas the conventional developer required a long development time. , development was poor in a short period of time.Example 8 Tetramethylammonium hydroxide (TMA I() 2.38%) was used as an organic base containing no metal ions.
is dissolved in water to make a developing solution for Bone-type photoresist, and a nonionic fluorine-based surfactant CFx (CF2
)? (CH2CH2O)1oH1CF3(CF2)7
(CH2)3 CON (CH2)2(CH7CL-1
, 0) 1014 , CF, (CF2) 7802N (
500 ppm of each of Cd(,) (CH2CH,O)14I-1 was added.

A photoresist film was prepared in exactly the same manner as in Examples 1 to 7, and the temperature of the developer was changed in 5°C increments within the range of 15 to 40°C, and the minimum exposure time (minimum exposure time required to faithfully reproduce the image) was determined as the sensitivity. ms) was measured. As shown in the figure, the temperature dependence of the developer was clearly reduced by adding the surfactant.

〔Effect of the invention〕

The developing solution of the present invention has good uniformity in developing a positive photoresist film, and the uniformity of the line width of the resist image in the photoresist film is significantly improved compared to the conventional one. In addition, the development time is half that of conventional products that do not contain nonionic fluorosurfactants (e.g., 60 seconds vs. 3 seconds).
A good resist image was obtained even at 0 seconds). Furthermore, the temperature dependence of the developer, especially in the case of an aqueous tetraalkylammonium hydroxide solution, is significantly reduced compared to conventional solutions that do not contain surfactants, significantly improving the tolerability of the developing process and facilitating process control. It became.

[Brief explanation of drawings]

The figure is a graph showing changes in the sensitivity of the developer depending on temperature, and shows the cases in which a nonionic fluorine-based surfactant was added to the developer (1 to 3) and the case in which it was not added (4). 1, CF3(CF2)7 (CH2CH2O)10
H500prim2, CF3 (CF2), (Cl2
)3CON (CH3)(CH2C)120 ), oi
(00ppm 3, CF3(CF2)7 S 02N (c, n,)
(CH2CH2O)! 4H00ppm

Claims (3)

[Claims] (1) A positive-working photoresist developer characterized by adding 50 to 5000 ppm of a nonionic fluorine-based surfactant to a positive-working photoresist developer whose main ingredient is an organic base that does not contain metal ions. (2) Nonionic fluorosurfactants have a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, Rf is the number of carbon atoms 3
~5 perfluoroalkyl group, A is a direct bond ▲
There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -SO_3-, -
CO_2- and -SO_2N(R_3)CH_2CO
A group selected from the group consisting of _2-, R is a hydrogen atom or an acyl group or alkyl group having 1 to 18 carbon atoms, n is an integer of 0 to 20, m is an integer of 0 to 5, R_
1, R_2, and R_3 are the same or different hydrogen atoms, alkyl groups having 1 to 6 carbon atoms, or ▲numerical formulas, chemical formulas, tables, etc.▼, x is an integer from 1 to 20, and R_4 is 1 carbon atom. The developer for positive photoresists according to claim (1), which is at least one kind selected from the group of fluorine atom-containing compounds represented by (3) Claims (1) to (2) wherein the metal ion-free organic base is at least one selected from tetraalkylammonium hydroxide and choline.
Developer solution for positive photoresist described in section )