JPH0721641B2 - Negative resist pattern forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a negative resist pattern used in the manufacture of semiconductor devices and the like, and particularly to a negative film suitable for submicron-order fine processing. The present invention relates to a mold resist pattern forming method.

(Prior Art) In recent years, a technique capable of forming a fine pattern has been required in order to manufacture these devices as semiconductor devices become highly integrated. Various techniques such as photolithography, X-ray lithography, and electron beam lithography have been proposed as a technique for responding to the request. Each of these lithographic techniques is an integration of various elements such as exposure technique, etching technique, resist material and the like, all of which are important for obtaining a fine pattern. Has a great influence on the resolution of the pattern and the throughput of the manufacturing process, and is one of the major factors for obtaining a desired fine pattern. Therefore, the development of new resists with excellent performance has been vigorously pursued.

The applicant of this application also used a novel resist, naphthoquinonediazide sulfonate of novolak (hereinafter,
Abbreviated as LMR. A resist consisting of, for example, JP-A-59-
It has been proposed in Japanese Patent 146047 and Japanese Patent Laid-Open No. 59-181535. This LMR is highly sensitive to electron beams and far-ultraviolet rays, has a sensitivity 10 times higher than that of PMMA (polymethylmethacrylate), and has excellent dry etching resistance. The resist pattern does not sag even at the baking temperature. Further, according to the method of the above publication, the exposed resist is developed using an acetic acid ester or an alkyl ketone solvent as a developing solution, and the resist pattern thus obtained is capable of forming a fine pattern on the order of submicrons. It could be done enough.

(Problems to be solved by the invention) However, when the above-mentioned LMR is exposed to ultraviolet rays of 350 to 450 nm, the exposed LMR cannot be developed with the above-described acetic ester or alkylketone-based developer, Therefore, there is a problem that a desired negative resist pattern cannot be obtained. Therefore, it is not possible to use an optical stepper, which is expected to be capable of forming a pattern on the order of submicrons, for patterning an LMR using light having a wavelength of 350 to 450 nm.

The object of the present invention is to eliminate the above-mentioned problems,
It is possible to obtain a desired resist pattern even with LMR exposed by 50 nm light, and to obtain a desired resist pattern even when exposed with deep ultraviolet rays or electron beams as in the past. It is to provide a method for forming a negative resist pattern capable of

(Means for Solving the Problems) In order to achieve this object, the negative resist pattern forming method of the present invention comprises a step of applying a naphthoquinone diazide sulfonic acid ester of novolak on a substrate to form a resist layer. And a step of exposing the above resist layer to ultraviolet rays or ionizing radiation, and a step of immersing the above exposed resist layer in water and then developing with a solution containing an organic solvent.

In carrying out the present invention, it is preferable to use monochlorobenzene, alkylbenzene, chlorinated alkane, chlorinated alkene, and the like, which are weakly polar organic solvents, as the above-mentioned organic solvent.

Further, in forming a negative resist pattern, if baking is performed after exposure, it is preferable to immerse the resist layer in water after the baking and before the development.

(Function) In the method for forming a negative resist pattern of the present invention, the developing solution contains an organic solvent having a weak polarity such as monochlorobenzene, and the exposed resist layer is treated with water before development with this developing solution. Is soaked in. This developing solution insolubilizes the portions of the LMR exposed by ultraviolet rays, far ultraviolet rays or ionizing radiation and dissolves the unexposed portions, so that desired development can be carried out.

Furthermore, although it is not clear, it is thought that the distortion of the LMR film is alleviated by immersing the exposed resist layer in water before development, and as is clear from the experimental results described later, a thick film thickness is obtained. Even with the formed LMR, desired development is performed without causing cracks in the LMR.

(Examples) Examples of the present invention will be described below. However, although the following description of the present invention is given with reference to preferable specific devices within the scope of the present invention, numerical conditions, etc.,
These are merely examples, and the present invention relates to these devices,
It is clear that the conditions are not the only ones.

Hereinafter, the resist pattern forming method of the present invention will be described with reference to FIGS. 1 (A) to 1 (C). It should be noted that these figures respectively show the cross section of the wafer according to the progress of formation of the resist pattern.

Example 1 First, 25% by weight of LMR was dissolved in methyl cellosolve acetate (MCA), and this solution was filtered through a filter having pores of 0.2 μm to prepare a resist solution. Incidentally, MCA
The amount of LMR dissolved therein is preferably in the range of 10 to 40% by weight based on MCA, and in such a case, a film having good LMR can be obtained.

A plurality of, for example, silicon substrates 11 as a base were prepared and these silicon substrates were divided into two groups. The above-mentioned resist solution was applied on one group of silicon substrates by spin coating to form a resist layer 13 having a thickness of 1.5 μm, and the other group of silicon substrates was coated with a 1.0 μm film by the same method. A thick resist layer 13 was formed (see FIG. 1 (A)). These silicon substrates were prebaked at a temperature of 90 ° C. for 60 seconds using a hot plate. Next, using a 1/5 reduction projection aligner (NA = 0.35), a g-line (wavelength is
The resist layer 13 of each silicon substrate 11 was selectively exposed to light 21 of 435.8 nm) (see FIG. 1 (B)). This exposure was performed with a dose amount of 150 mJ / cm ₂ . Then, using a hot plate, the silicon substrate was baked at a temperature of 110 ° C. for 60 seconds in this case. When the exposure is performed with light having a single wavelength, it is preferable to perform the baking after the exposure, which reduces the influence of standing waves on the resist layer. The baking temperature is changed to an appropriate value according to the design of the resist pattern. In addition, when exposure is performed using multiple wavelengths, baking may not be necessary, and the presence or absence of this baking may be changed according to the design of the resist pattern.

The resist pattern forming method of the present invention includes a step of immersing the exposed resist layer in water after completion of baking when such baking is performed, or after completion of exposure when not baking and before development. There is. In the case of this embodiment, in a water tank in which the water temperature is kept at 32 ° C,
Each of the exposed and baked silicon substrates was immersed for 2 minutes, and then dried with a nitrogen (N ₂ ) blower. Next, as a developing solution containing an organic solvent, in the case of this embodiment, an organic solvent having a weak polarity such as monochlorobenzene is included, and for example, a developing solution which is a mixed solution of cyclohexane 1.5 (volume ratio) to monochlorobenzene 10 is used. As a result, the resist layer with a thickness of 1.0 μm is developed for 40 seconds, and the resist layer with a thickness of 1.5 μm is developed for 60 seconds. The unexposed part was removed. The developed product was rinsed with cyclohexane for 10 seconds. The resist pattern 13a of each silicon substrate thus formed
When the scanning electron microscope (SEM) was used to observe (Fig. 1 (C)), a 0.7 μm punched pattern was resolved in each case, and a resist film thickness of 1.0 μm was also observed. No crack was found around the punched pattern even when the thickness was 1.5 μm.

In addition, the temperature of the water for immersing the exposed resist layer is 10 to 40
The temperature range is preferably in the range of ℃, and when the water temperature is higher than 40 ℃, the occurrence of cracks around the pattern could not be suppressed even if the dipping treatment was performed. It was also found that the longer the immersion time, the greater the effect, but the occurrence of cracks can be prevented if the time is about 1 to 5 minutes.

Even when the organic solvent is a suitable organic solvent other than chlorobenzene, for example, alkylbenzene, chlorinated alkane such as dichloromethane, or chlorinated alkene such as trichlorethylene, the same effect as that of the example is expected. You can do it.

Comparative Example The resist layer was not soaked in water after the completion of exposure, and the resist layer was formed, pre-exposure baking, exposure, post-exposure baking and development were performed in the same manner as in Example 1.

When the resist pattern of each silicon substrate of the comparative example formed in this way was observed by SEM, a 0.7 μm punched pattern was resolved in all cases, but with a resist film thickness of 1,5 μm, Generation of cracks was observed around the pattern. On the other hand, in the case of 1.0 μm, no crack was found around the punched pattern.

Further, in the resist pattern forming method as in Example 1, when the exposure was carried out using ionizing radiation, a desired resist pattern similar to that in Example 1 could be obtained, but the same formation as in Comparative Example. In the resist pattern obtained by the method, cracks were observed when the LMR film thickness was large as in the comparative example.

(Effects of the Invention) As is clear from the above description, according to the resist pattern forming method of the present invention, a weakly polar organic solvent such as monochlorobenzene is contained as a developing solution for the resist layer constituted by LMR. Since it is used, it was exposed by a high energy source such as ionizing radiation and deep ultraviolet rays.
Not only LMR, but also LMR exposed to ultraviolet rays in the long wavelength region of 350 to 450 nm can be developed, and in any case, the desired resist pattern could be obtained. .

Furthermore, by immersing the exposed resist layer in water before development, it was possible to obtain a resist pattern without causing cracks in the LMR even when the film thickness of the LMR was large.

Therefore, the LMR, which is an excellent resist, can be used for forming a fine pattern without being restricted by the wavelength of the exposure source and even when a resist layer having a large film thickness is required.

Furthermore, since the negative resist pattern forming method of the present invention does not require the provision of new equipment or the like, there is no fear of increasing the manufacturing cost at all, and in this respect also, the industrial value is very large. is there.

[Brief description of drawings]

1 (A) to 1 (C) are process diagrams of forming a resist pattern, which are used for explaining the negative resist pattern forming method of the present invention. 11 …… Underlayer (silicon substrate) 13 …… Resist layer (LMR) 13a …… Resist pattern 21 …… UV rays or ionizing radiation.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaki Asano 1-9-17 Azabudai, Minato-ku, Tokyo Within Fuji Yakuhin Kogyo Co., Ltd. (72) Kenji Kobayashi 1-9-17 Azabudai, Minato-ku, Tokyo Fuji Yakuhin Kogyo Co., Ltd.

Claims (2)

[Claims] 1. A step of applying a naphthoquinonediazide sulfonic acid ester of novolak on a substrate to form a resist layer, a step of exposing the resist layer to ultraviolet rays or ionizing radiation, and a step of immersing the exposed resist layer in water. And a step of developing with a solution containing an organic solvent afterwards. 2. The method of forming a negative resist pattern according to claim 1, wherein the organic solvent is monochlorobenzene.