JPH04344649A - Photoresist developing solution - Google Patents

Abstract

PURPOSE:To provide the photoresist developing solution capable of forming a good pattern high in resolution and small in the solubility of the unexposed parts of the photoresist. CONSTITUTION:This photoresist developing solution is characterized by mixing an alicyclic alcohols or ketones having at least one alkyl group, such as 2- methylcyclohexanol or 3-methylcyclohexan-one, with an aqueous solution of alkali, such as sodium hydroxide or tetraalkylammonium hydroxide in an amount of 0. 2-2wt.%.

Description

[Detailed description of the invention]

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0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoresist developer.

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[Prior art and problems to be solved by the invention] In recent years,
In the field of microelectronics, the degree of integration of integrated circuits is rapidly increasing. Therefore, the photoresist used for pattern formation is required to have high resolution, and generally a positive resist is used, which is a combination of a resin soluble in an alkaline aqueous solution and a naphthoquinone diazide compound as a photodegrading agent. Further, negative resists that are soluble in alkaline aqueous solutions and have improved resolution have been developed.

[0005]

An alkaline aqueous solution is used as a developer for such photoresists, but since photoresists are generally hydrophobic, they do not easily leak into the developer. For this reason, the developer causes uneven development due to non-uniform development, which may reduce the uniformity within the silicon wafer surface, which affects the yield of integrated circuits.

[0006]

Furthermore, for the same reason, in the case of a fine pattern, the developer cannot sufficiently penetrate to the base, causing problems such as edge cutting at the base, resulting in a decrease in dimensional accuracy.

[0007]

As a solution to this problem, it has been proposed to add various surfactants or organic solvents to the alkaline aqueous solution to improve the wettability of the photoresist. However, when a surfactant is added, it may reduce the development rate of the photoresist or reduce the ratio of dissolution rates of exposed and unexposed areas, ie, dissolution selectivity. This becomes a big problem as patterns become finer. Furthermore, the developer tends to foam, and the resulting foam may cause poor development.

[0008]

[0006] Furthermore, when adding an organic solvent, a large amount of organic solvent is generally required in order to produce an effect, and in such a case, as with surfactants, the development speed decreases and the organic solvent also damages the photoresist in non-exposed areas. Since the photoresist is melted, the remaining film rate of the photoresist decreases, and as a result, the cross-sectional shape of the resist pattern tends to deteriorate.

[0009]

[0007]Therefore, there has been a strong desire to develop a photoresist developer which has good wettability without reducing the photoresist development speed and dissolution selectivity, and which exhibits less foaming and less reduction in film retention.

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[0008]

[0011]

[Means for Solving the Problems] The present inventors have continued intensive research to solve the above problems. As a result, they discovered that the problem could be solved by blending a specific compound into an alkaline aqueous solution and proposed the present invention.

0012

That is, the present invention is a photoresist developer comprising 0.2 to 2% by weight of an alicyclic alcohol or ketone having at least one alkyl group in an alkaline aqueous solution.

[0013]

[0010] As the alkaline aqueous solution in the present invention, any conventionally known developer solution for photoresist can be used without any restriction. Specifically, aqueous solutions of alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; aqueous solutions of amines such as propylamine, butylamine, dibutylamine, and triethylamine; or trimethyl(2-hydroxyethyl)ammonium hydroxide; These include aqueous solutions of quaternary ammonium compounds such as tetramethylammonium hydroxide and tetraethylammonium hydroxide. Of these, especially trimethyl (2
Preference is given to using an aqueous solution of a quaternary ammonium compound such as -hydroxyethyl) ammonium hydroxide or tetramethylammonium hydroxide. Also,
An aqueous solution containing a combination of two or more of the above various alkaline compounds may be used. The concentration of the alkaline compound in the alkaline aqueous solution is preferably 0.1 to 10% by weight, preferably 1 to 5% by weight.

[0014]

The most important feature of the present invention is that the alkaline aqueous solution contains 0.2-2. By weight%.

[0015]

Examples of alicyclic alcohols having at least one alkyl group include alkyl-substituted compounds of cyclohexanol, specifically 2-methylcyclopentanol, 1-methylcyclohexanol, and 3-methylcyclohexanol. , 1,3-dimethylcyclohexanol, 2,4-dimethylcyclohexanol, and the like.

[0016]

Further, examples of alicyclic ketones having at least one alkyl group include cyclohexanone as a saturated ketone, cyclopentenone as an unsaturated ketone,
Alkyl substituted compounds of each ketone such as cyclohexenone, specifically 1-methylcyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 2,
4-dimethylcyclohexanone, 2,6-dimethylcyclohexanone, 3-methyl-2-cyclopentenone, 3
, 5,5-trimethyl-2-cyclohexenone and the like.

[0017]

[0014] The alkyl group in the above alicyclic compound is not limited by the number of carbon atoms, but methyl and ethyl groups are preferred, with methyl being particularly preferred.

[0018]

The alicyclic compound must have at least one alkyl group. When a compound without an alkyl group is used, it is not effective in improving wettability, and a large amount of the compound must be added in order to obtain the effects of the present invention. This is not desirable because of the adverse effects mentioned above.

[0019]

[0016] It appears that the greater the number of alkyl groups, the more the wettability is improved, but at the same time, the solubility of the alicyclic compound in the developing solution deteriorates, and the amount added is limited, so there is a limit to the effect. be.

[0020]

For these reasons, it is necessary that the alicyclic compound having an alkyl group in the present invention has an appropriate balance between wettability improving effect and solubility. A suitable number is 1 to 3.

[0021]

[0018] In the present invention, the blending amount of the alicyclic compound is as follows:
The amount is 0.2 to 2% by weight, preferably 0.4 to 1.5% by weight, based on the alkaline aqueous solution. If this amount is less than 0.2% by weight, the wettability of the above-mentioned developer to the photoresist will be insufficient, while if it is more than 2% by weight, the photoresist in the non-exposed area will dissolve in the compound, resulting in a residual film. As a result, the shape of the resist pattern deteriorates.

[0022]

The developer of the present invention can be applied to both positive type and negative type photoresists without any limitation as long as it is an alkaline aqueous solution soluble photoresist. It is preferably applied to a positive resist in which a naphthoquinone diazide compound is combined with an alkaline aqueous solution-soluble resin. Examples of the alkaline aqueous solution-soluble resin include novolak resin, polyhydroxystyrene, and derivatives thereof. Further, examples of the above-mentioned negative resist include those in which a resin soluble in an alkaline aqueous solution is combined with a bisazide compound such as 4,4'-diazidodiphenyl sulfide or 4,4'-diazidophenylmethane.

[0023]

The developing method using the developer of the present invention is not particularly limited, and known methods such as the immersion method and the paddle method can be applied.

[0024]

The developer of the present invention may contain additives commonly used in conventional developers, if desired. Examples of such additives include wetting agents, stabilizers, solubilizing agents, and the like, and these can be added alone or in combination of two or more.

[0025]

[0022]

[0026]

[Effects] The photoresist developer of the present invention has good wettability to photoresists and good photoresist development speed. Further, no decrease in solubility selectivity was observed. Therefore, when this developer is used for photoresist, for example, a good pattern with high resolution can be produced without the pattern base being trailed or developing not being completed within the development time and leaving undeveloped parts. can be formed. Furthermore, since the photoresist in non-exposed areas is hardly dissolved, the remaining film rate is good.

[0027]

[0023]

[0028]

EXAMPLES In order to explain the present invention more specifically, Examples and Comparative Examples will be given below, but the present invention is not limited to these Examples in any way. Example 1~
11 and Comparative Examples 1 to 3

[0029]

A developing solution was prepared by blending the compounds shown in Table 1 with a 2.4% by weight aqueous solution of tetramethylammonium hydroxide.

[0030]

Next, a positive type photoresist containing a combination of novolac resin and naphthoquinone diazide compound was coated on the silicon wafer to a thickness of 1.3 μm, and then prebaked at 90° C. for 30 minutes in a clean oven. A stepper (manufactured by Nikon Corporation) is placed on this silicon wafer.
After baking the pattern with SR-1505G), development was performed by dipping at a temperature of 22° C. for 1 minute using the developer prepared above. The photoresist pattern thus obtained was observed using a scanning electron microscope, and the presence or absence of development residue and the shape of the pattern were evaluated.

[0031]

[0026] In addition, two types of silicon wafers that had been subjected to only the prebaking were separately prepared, and the following two evaluations were carried out.

1. Developed under the same conditions as above,
Film thickness meter (manufactured by Nanometric, Nanospec Model 2)
00), the resist film thickness was measured and the remaining film rate was determined. The residual film rate is defined by the formula below.

2. In order to check the degree of wetting, the developer was dropped onto the photoresist, and the contact angle of the developer was measured using a contact angle meter (Model CA-S150, manufactured by Kyowa Kaimen Kagaku Co., Ltd.).

In this case, the smaller the contact angle, the better the wettability.

[0035]

The above results are shown in Table 1. In addition, in Table 1, when observing the pattern, the shape of the pattern is ○ if the cross section of the pattern is a good rectangle and the base has a good hem, while the shape of the pattern is poor or the base has a hem. Those that occurred are indicated as ×.

[0036]

[0028]

[0037]

[Table 1]

Claims (1)

[Claims] 1. A photoresist developer comprising 0.2 to 2.0% by weight of an alicyclic alcohol or ketone having at least one alkyl group added to an alkaline aqueous solution.