JPH0567028B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a developer for positive photoresist,
More specifically, it is a developer that is particularly suitable for use in image formation using quinonediazide-based positive photoresists, and has improved wettability to photoresist films, improved dissolution selectivity between exposed and non-exposed areas, and improved development ability. The present invention relates to a good positive photoresist developer that does not cause defects and has little temperature dependence in dissolution of exposed areas, and is useful for manufacturing semiconductor integrated circuit devices and the like. [Prior Art] Conventionally, when manufacturing semiconductor integrated circuit elements, integrated circuit manufacturing masks, printed wiring boards, printing boards, etc., selective etching or diffusion treatment is applied to the underlying substrate. At this time, a film is formed using a composition sensitive to actinic rays such as ultraviolet rays, X-rays, and electron beams, so-called photoresist, in order to selectively protect the unprocessed portions of the underlying substrate. A method is used in which an image is then formed by imagewise exposure and development. This photoresist has positive type and negative type.
The former is a type in which the exposed area dissolves in the developer but the non-exposed area does not, and the latter is the opposite type. A typical example of the former positive type photoresist is a combination of an alkali-soluble novolak resin as a base and a naphthoquinonediazide compound as a photodegrading agent. An alkaline aqueous solution is used as a developer for this naphthoquinonediazide-based positive photoresist, but when manufacturing semiconductor devices, using an alkaline aqueous solution containing metal ions as a developer has a negative effect on product characteristics. , a developer that does not contain metal ions, such as tetramethylammonium hydroxide (IBM "Technical Disclosure Bulletin" Vol. 13,
No. 7, p. 2009, 1970) and choline (US Pat. No. 4,239,661). One of the problems when forming images using positive photoresists is the change in sensitivity due to the temperature of the developer, so-called temperature dependence of the developer. Because of this, 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 type developing apparatuses used in the manufacture of semiconductor integrated circuits are becoming common in order to automate the photoresist process. In this method, a developer is dropped onto the wafer surface coated with a photoresist film, spread, and then the developer is dropped again after a certain period of time to develop the wafer while the wafer remains stationary. In this method, the speed at which the developer spreads over the entire surface of the wafer is the key to determining the uniformity of the line width of the resist image within the wafer.The larger the diameter of the wafer, the more problematic the spread of the developer over the entire surface becomes. The wettability of the liquid is important. In order to improve wettability, JP-A-58-57128 discloses adding 1 to 50% by weight of an organic solvent or a surfactant, but for example, developing for positive photoresists such as tetramethylammonium hydroxide When a hydrophilic solvent such as alcohol or ethylene glycol monoalkyl ether is added to the liquid, a relatively small amount will have no effect on wettability, and a relatively large amount will dissolve even the parts of the resist image that should be left and cause the image to deteriorate. This means that you will not be able to obtain
Further, even when a surfactant is used, there is a problem that the developer is temperature dependent, and as the temperature increases, the sensitivity increases and the amount of film loss in unexposed areas also increases. In addition, in the developer for positive photoresist,
Characteristics such as completely dissolving the exposed area, hardly dissolving the unexposed area, and not causing any change in film thickness before and after development, so-called dissolution selectivity, are important, and Japanese Patent Application Laid-Open No. 58-9143 The publication discloses the addition of a quaternary ammonium type surfactant, and JP-A-58-150949 discloses the addition of a quaternary ammonium salt. Furthermore, in order to increase the contrast of positive photoresists, developing with a solution containing a combination of an alkali metal base and a nonionic fluorine-containing surfactant is disclosed in JP-A-60-12547. 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. [Problems to be Solved by the Invention] An object of the present invention is to solve such problems and to provide a method suitable for image formation using a naphthoquinonediazide-based positive photoresist, that is, having improved wettability to a photoresist film. To provide a developer for a positive photoresist which has improved dissolution selectivity between exposed and non-exposed areas, does not cause development defects, and has less temperature dependence of dissolution in exposed areas and can be used for manufacturing semiconductor integrated circuit elements. There is a particular thing. [Means for Solving the Problems] As a result of extensive research, the present inventors have found that the above objective can be achieved by adding a specific fluorine-based surfactant to a conventional positive photoresist developer. We have discovered that this can be achieved, and based on this knowledge, we have completed the present invention. That is, the present invention provides a positive photoresist developer containing an organic base containing no metal ions as a main ingredient.
50 to 5000 ppm of anionic fluorine-based surfactant
The object of the present invention is to provide a developer for a positive photoresist, which is characterized in that it contains the following: 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 they are. These include, for example, aryl and alkyl amines containing linear, branched or cyclic primary, secondary and tertiary amines, such as 1,3-diaminopropane. alkylene diamines, arylamines such as 4,4'-diaminodiphenylamine, bis-
Amines such as (dialkylamino)imines, heterocyclic bases having 3 to 5 carbon atoms and 1 or 2 heteroatoms selected from nitrogen, oxygen and sulfur in the ring skeleton, such as pyrrole, pyrrolidine , pyrrolidone, pyridine, morpholine, pyrazine, piperidine, oxazole, thiazole, or a lower alkyl quaternary ammonium base. 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 solubilizing agents, additives commonly used in conventional developing solutions of the present invention include:
Cationic surfactant and non-surfactant quaternary ammonium compounds for improving the dissolution selectivity between exposed and non-exposed areas of a positive photoresist film;
1 as an additive to prevent thin film and scum remaining after development of positive photoresist film.
These include alcohols and the like, and each of these can be used alone or in combination. The anionic fluorine-containing surfactant added to the developer of the present invention has the general formula ()R _f COOM and the general formula ()R' _f SO ₃ M [where R _f and R' _f are carbon numbers]. 2～
It is a fluorinated hydrocarbon group in which some or all of the hydrogen atoms in a saturated or unsaturated hydrocarbon group of 20 are replaced with fluorine atoms, and M is H, NH ₄ or N
(R ₁ R ₂ R ₃ R ₄ ), and R ₁ , R ₂ , R ₃ , and R ₄ are hydrogen atoms or lower alkyl groups, and are the same or different. At least one selected linear or branched perfluoroalkyl carboxylic acid _Co
F _2o+1 COOH, perfluoroalkyl sulfonic acid
C _o F _2o+1 SO ₃ H, fluorinated alkyl carboxylic acid C _o
F _2o+1 C _n H _2n COOH, fluorinated alkenyl carboxylic acid C _o F _2o+1 CH=CHC _n H _2n COOH, fluorinated alkyl sulfonic acid C _o F _2o+1 C _n H _2n SO ₃ H, Fluorinated alkenesulfonic acid C _o F _2o+1 CH=CHC _n H _2n
SO ₃ H [Here, n = 1 to 10, m = 1 to 15]
including the acid itself and its ammonium salts and tetraalkylammonium salts, specifically perfluorocaprylic acid C ₇ F ₁₅ COOH, perfluorooctyl sulfonic acid C ₈ F ₁₇ SO ₃ H, perfluorocaprylic acid ammonium C ₉ F ₁₉ COONH ₄ , tetramethylammonium perfluorocaprylate
C ₇ F ₁₅ COON (CH ₃ ) ₄ , C ₅ F ₁₁ (CH ₂ ) ₃ COOH, CF ₃
(CF ₂ ) ₃ CF (CF ₃ ) (CH ₂ ) ₁₀ COONH ₄ , CF ₃
Examples include, but are not limited to, (CF ₂ ) ₆ CH=CH(CH ₂ ) ₂ COONH ₄ and the like. Note that these may be used alone or in combination of two or more. The amount of anionic fluorine-based surfactant used in the present invention is 50 to
In the range of 5000 ppm, preferably in the range of 100 to 1000 ppm. If it is less than this range, there will be no wettability effect, and if it exceeds this range, the image shape obtained will lack sharpness, which is not preferable. [Function] Addition of an anionic fluorine-containing surfactant to a positive photoresist developer containing an organic base that does not contain metal ions improves the wettability of the developer to the photoresist film. It has the effect of improving the spreading rate over the entire surface of the wafer or the uniformity of development. If an anionic fluorine-based surfactant was not added, air bubbles would adhere to the surface of the photoresist film, making development impossible or taking time. The bubbles quickly spread uniformly over the entire surface of the photoresist film and float to the surface of the developer, allowing for good development. Furthermore, the addition of the anionic fluorine-containing surfactant of the present invention reduces the temperature change in the solubility characteristics of the positive photoresist developer, which is based on an organic base that does not contain metal ions, and expands the tolerance of the developing process. do. In particular, in the case of a developer based on tetraalkylammonium hydroxide, a positive photoresist is a combination of a novolac resin as a film-forming component and a polyhydroxybenzophenone ester of naphthoquinonediazide-5-sulfonic acid as a photosensitive component. When developing, if no fluorosurfactant is added, the developer temperature is
The solubility is highest at around ~25℃, and the solubility decreases at higher or lower temperatures, but
By adding the anionic fluorine-containing surfactant of the present invention, this temperature dependence is significantly reduced and the tolerability of the developing process is greatly improved. The addition of the anionic fluorine-based surfactant of the present invention acts on a developer based on an organic base that does not contain metal ions, spreads the developer uniformly over the photoresist film, and improves wettability. , and its activity is not impaired by temperature changes. [Example] Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 12, Comparative Examples 1 to 5 Tetramethylammonium hydroxide (TMAH) 2.38 as an organic base containing no metal ions
% and 4.2% choline are each dissolved in water to prepare a positive-working photoresist developer, and an anionic fluorine-based surfactant shown in Table 1 is added to each of these to prepare a positive-working photoresist developer of the present invention. And so. For comparison, a sample to which the above surfactant was not added was also prepared. Spinner (Tatsumo resist coater TR
A positive photoresist OFPR-5000 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was coated on a 4-inch silicon wafer to a film thickness of 1.3 μm, and prebaked at 110° C. for 90 seconds on a hot plate.
After exposure using a DSW4800 reduction projection exposure system (manufactured by GCA) and a test chart manufactured by Dai Nippon Printing Co., Ltd., static development was performed using the developer prepared above using a homemade static developing device, and pure water After rinsing with water for 30 seconds and drying with nitrogen gas, the resulting resist pattern on the wafer was observed. The results are shown in Table 1. The developer of the present invention was able to uniformly develop the wafer surface within a short time without any dimensional variation, whereas the conventional developer required a long time and resulted in poor development in a short time. It was hot.

【table】

〔Effect of the invention〕

The developer of the present invention has good uniformity in developing a positive photoresist film, and the uniformity of line width of a resist image within a wafer is significantly improved compared to the conventional developer. In addition, a good resist image was obtained even when the development time was half that of the conventional one (for example, 60 seconds vs. 30 seconds) compared to the conventional one without the addition of anionic fluorine-based surfactant. Furthermore, the temperature dependence of the developing solution, especially in the case of an aqueous tetraalkylammonium hydroxide solution, is significantly reduced compared to conventional solutions that do not contain surfactants, and the tolerance of the developing process is significantly improved, making process control easier. Summer.

[Brief explanation of the drawing]

The figure is a graph showing changes in the sensitivity of the developer depending on temperature, and shows the results with and without the addition of anionic fluorine surfactant (C ₇ F ₁₅ COONH ₄ ) at different amounts (100ppm, 50ppm, 1000ppm). (0).

Claims (1)

[Scope of Claims] 1. For positive photoresist, characterized in that 50 to 5000 ppm of an anionic fluorine-based surfactant is added to a positive photoresist developer whose main ingredient is an organic base that does not contain metal ions. developer. 2 Anionic fluorine-based surfactants have the general formula ()R _f COOM and the general formula ()R′ _f SO ₃ M [wherein R _f and R′ _f are saturated or unsaturated with 2 to 20 carbon atoms. A fluorinated carbon group in which some or all of the hydrogen atoms of a saturated hydrocarbon group are replaced with fluorine atoms, M is H, NH ₄ or N (R ₁ R ₂ R ₃ R ₄ ), and R ₁ , R ₂ ,
R ₃ and R ₄ are hydrogen atoms or lower alkyl groups, and are the same or different. Developer for photoresist. 3. The positive photoresist developer according to claims 1 to 2, wherein the organic base that does not contain metal ions is at least one selected from tetraalkylammonium hydroxide and choline.