JPS61241745A - Negative type photoresist composition and formation of resist pattern - Google Patents

Abstract

PURPOSE:To form a negative type photoresist compsn. capable of submicron patterning with a reduction projection type aligner and superior in heat and dry etching resistances of the formed resist pattern by using a compsn. of novolak naphthoquinonediazidesulfonate ester. CONSTITUTION:The negative type photoresist compsn. is made of novolak naphthoquinonediazidesulfonate ester (NQN). Since it has high absorption coefft. in the region of 300-450nm wavelength and high sensitivity, it is especially adapted to a negative UV resist. It is rendered to a negative type, presumably, mainly by the photochemical change that this NQN is converted into indenecarboxylic acid by light irradiation, resulting in changing its polarity, and since it is not deteriorated in resolution by heating at 60-100 deg.C after the exposure and before development, it can be effectively enhanced in sensitivity.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a resist composition for microfabrication used in the manufacture of semiconductor devices, etc., and a method of forming a fine resist pattern on the order of submicrons using the same. .

(Prior Art) In recent years, demands for higher integration of semiconductor devices and the like have been increasing, and along with this, technical demands regarding the formation of fine patterns have also become increasingly strict. As a microfabrication technology that meets these demands, a resist pattern is formed using ionizing radiation such as electron beams, X-rays, and short wavelength ultraviolet rays, and then the resist pattern is precisely formed by dry etching using ions, plasma, etc. There is a need for a method for transferring to an underlying layer such as a substrate.

By the way, for the formation of fine patterns before and after IIL11, considering the resolution, the price of the device, and the throughput, a reduction projection type transfer device (aligner) using light is most promising. However, in this case, for the aligner, it is necessary to develop a lens with a large numerical aperture and a large exposure area, and on the other hand, for the resist, it is necessary to develop a lens with a high resolution and a large exposure area.
It is desired to develop an excellent resist material that is not affected by reflection from the substrate side.

Conventionally, positive photoresists made of novolac and naphthoquinone diazide, such as Az-1350J, are commonly used in reduction projection aligners.
(product name manufactured by SHIPLEY).

However, these photoresists have low absorption at the exposure wavelength of G-line (438n), and if the substrate has a high reflectance such as a layer or has a step, the influence of reflection from the substrate during exposure may occur. The receiver cannot form a beautiful and sharp pattern.

In order to prevent such reflection from affecting patterning, methods have been proposed in which an antireflection film is applied to the substrate and a method in which the resist is formed into a multilayer structure.

(Problem to be solved by this invention) However,
Such a method requires a complicated process, and furthermore, Az-1
7 Otoresist such as 350J does not have sufficient heat resistance.1 For example, the resist may blur at temperatures of about 100°C, or if the resist area is large, it may shrink, and furthermore, the resolution is not sufficient. There was a drawback.

The purpose of this application is to enable submicron patterning with a reduction projection aligner! An object of the present invention is to provide a negative photoresist composition in which the formed resist pattern has excellent heat resistance and dry etching resistance.

Another object of this application is to provide a resist pattern forming method using this resist composition.

(Means for Solving the Problems) In order to achieve the object of this application, in a negative photoresist composition for ultraviolet rays for forming a resist pattern according to the present invention, this composition is prepared using naphthoquinonediazide sulfone of novolak. It is characterized by being an acid ester.

Furthermore, in order to achieve the other object of this application, a film of novolak naphthoquinonediazide sulfonic acid ester was formed as a resist on this underlayer, this film was selectively exposed to ultraviolet light, and then developed. To form a negative resist pattern, this ultraviolet ray is applied at 300 to 4501 cm, and the film is developed using a developer containing benzene, monochlorobenzene, or alkylbenzene to remove the unexposed parts of the film. It is characterized by removal.

(Function) As described above, in the present invention, a photoresist film for ultraviolet rays is formed from novolac naphthoquinonediazide sulfonic acid ester (hereinafter simply referred to as NQN). This film is from 300 to '450! The unexposed portions are removed by developing with a developer in which benzene, monochlorobenzene or alkylbenzene is dissolved in cyclohexane or other suitable solvent. In this case, the furkylbenzene is xylene, It can be toluene or other similar alkylbenzenes.

In the present invention, this NQN has a large extinction coefficient for wavelengths of 300 to 450 nm and is highly sensitive, so it is particularly suitable for use as a negative photoresist for ultraviolet rays. Furthermore, it is thought that the mechanism by which this NQN resist material becomes negative is mainly due to the change of quinone diazide into indene carboxylic acid upon irradiation with light, that is, the change in polarity.

Further, heating at 60 to 100° C. after exposure and before development has the effect of increasing sensitivity without reducing resolution.

As described above, the NQN photoresist of the present invention utilizes the photoreaction of quinone diazide, and a photosensitive group is introduced by directly esterifying the OH group of novolac with naphthoquinone diazide sulfonic acid chloride. In addition, it has the effect of increasing solubility in nonpolar solvents such as monochlorobenzene and xylene.

In addition, the extinction coefficient of this NQN photoresist at the line is 1.5/μm, which is higher than the conventional resist Az-13.
It is extremely large compared to 0.2/JL■ of 50J, so
Even when a layered substrate with high reflectance is used as the underlayer, it is not substantially affected by reflection from the substrate, and therefore a beautiful and sharp pattern can be formed. Furthermore, since this NQN is not swollen by the developer used in the invention described above, a pattern with high resolution can be obtained.

Furthermore, this NQN does not sag even at a high temperature of about 200° C., and shrinks less, although it varies somewhat depending on the form of the pattern, and has superior heat resistance characteristics compared to conventional ones.

Furthermore, since the naphthoquinonediazide sulfonic acid ester of novolak has excellent dry etching resistance, the underlying layer can be etched using plasma etching.

(Examples) Examples of the present invention will be described below. The following examples will be described in detail using materials and numerical conditions within a specific preferred range of the present invention, but these conditions are merely illustrative and the present invention is not limited thereto. it is obvious.

Support 1" In this example, a silicon wafer is used as the base layer,
A photoresist film is deposited thereon. To form a resist film, novolac naphthoquinone diazide sulfonic acid ester (NQN) is dissolved in 10% to 40% by weight methyl cellosolve acetate, and the solution is mixed with 0.2% by weight of methyl cellosolve acetate.
After filtration with a so-called filter, it was coated onto a wafer with a thickness of 0.7 IL layer by spin coating.

Next, the wafer on which the NQN film was formed was prebaked at a temperature of 70° C. for about 30 minutes.

Next, exposure was performed using a 5:1 reduction type aligner.

Selective exposure was carried out using J-line as the exposure wavelength and at a dose of 50 J/cm 2 , thereby transferring a photomask pattern to this NQN film. after that.

The exposed wafer with the NQN film was baked at a temperature of 100° C. for about 30 minutes.

Next, in this example, monochlorobenzene l at a volume ratio of 1
This NQN film was developed for 35 seconds using a mixed solution of 23° C. in a ratio of 1 part O to cyclohexane as a developer. Subsequently, when rinsing was performed with cyclohexane for 10 seconds, grooves were formed in the unexposed areas under the opaque part of the photomask where the ultraviolet rays did not hit, exposing the surface of the underlayer, and creating a negative resist pattern. was formed.

When the resist pattern thus formed was observed with a scanning electron microscope (SEX), it was confirmed that a beautiful and sharp negative resist pattern with an almost rectangular cross-sectional shape was formed. It was also confirmed that the lines and spaces of the 6 Hiro layer were resolved.

In this example, the board is an M board, and the outside of the scenery is the example
Film formation, exposure, and development were performed under the same conditions.

According to the same electron microscope observation as described above, it was found that a line-and-space resist pattern of 0.7 ILm was obtained.

I) In this example, when the resist pattern formed according to Example I was baked at 150° C. and then observed under an electron microscope, no sagging of the resist due to baking was observed.

For comparison, Az-1350J was patterned under the same conditions and baked at 150°C.

The pattern became sagging and the cross-sectional shape became round.

Actual jth IN A resist film is formed in the same manner as in Example I, and 1
When exposed at a dose of 00 sJ/cm2, developed for 80 seconds using a solution of 10 parts xylene to 1 part cyclohexane at 23°C, and rinsed with cyclohexane, a line and space of 0.7 JL was obtained. A negative pattern was obtained.

As a comparative example, a resist film was formed by coating Az-1350J It on a silicon wafer to a film thickness of 1.0 IL layer, and then prebaking was performed at 80° C. for 20 minutes.

Exposure was carried out at a dose of 80 sJ/cm 2 using the same reduction projection type apparatus as used in Example I.

Using monochlorobenzene at 23°C as a developer,
When the resist film was developed for seconds, both the exposed and unexposed parts of the resist film were not dissolved at all, and therefore no resist pattern could be formed. In Az-1350J, quinone diazide, which is a photosensitizer, changes to indenecarboxylic acid, but it is understood that patterning cannot be performed because the novolac and photosensitizer are not dissolved in a nonpolar solvent such as monochlorobenzene.

Retaining mouth 1J Az-135 (I
A resist film of J is formed, exposed to light, and Az-135
When developed with an alkaline developer for OJ, a pattern up to the IIL irises could be dissolved, but a pattern with dimensions smaller than that could not be formed.

It should be noted that the above-mentioned embodiments are only examples of the present invention, and it is clear that the present invention is not limited thereto.For example,
The base layer may be other than the substrate.

Furthermore, it is known that the above-mentioned NQN can form a positive pattern by developing it with an alkaline developer after exposure, but when used as a positive type, this resist has a large extinction coefficient, so the cross section of the pattern becomes trapezoidal, a desirable rectangular pattern cannot be obtained, and it cannot be used as a positive type for forming fine patterns.

(Effects of the Invention) As is clear from the above explanation, the negative photoresist composition of the present invention has excellent dry etching resistance, and can be used as a negative photoresist with nonpolar solvents such as monochlorobenzene and xylene. Patterns can be formed. Moreover, since this NQN composition does not swell with these developers, a pattern with high resolution can be obtained.

Furthermore, this NQN has excellent heat resistance, and although it depends on the form of the pattern, there is no problem with shrinkage up to about 200"O, and all pattern forms have good shrinkage and blurring. The temperature that does not pose a problem is 150~1B (1℃
The temperature is about.

Furthermore, NQN has a large extinction coefficient in the wavelength range of 300 to 45 nm, so it is highly sensitive and even when formed as a resist on a reflective or stepped substrate, the reflection of light will not affect patterning. Since there is no influence, the pattern can be formed almost in accordance with the mask pattern.

In this way, using a resist with high sensitivity, high resolution, and excellent dry etching resistance, 300 to 450 nm
Since the resist pattern is exposed to ultraviolet rays of m and is processed using a developer suitable for this, it is possible to form a beautiful and sharp resist pattern on the order of submicrons even when patterning is performed using a reduction projection aligner.

Therefore, the resist pattern forming method of the present invention
It is suitable for use in manufacturing highly integrated semiconductor devices such as I.

Patent applicant: Oki Electric Industry Co., Ltd. Same as above, Fuji Pharmaceutical Industry Co., Ltd., Agent: Patent attorney Takashi Ogaki 1 (','
,,” Procedural Amendment April 7, 1986

Claims (2)

[Claims] (1) A negative photoresist composition for ultraviolet rays for forming a resist pattern, characterized in that the composition is a naphthoquinonediazide sulfonic acid ester of novolac. (2) Forming a film of naphthoquinonediazide sulfonic acid ester of novolac as a resist on the base layer, selectively exposing the film to ionizing radiation, and then developing it to form a negative resist pattern. , Negative type, characterized in that the ionizing radiation is ultraviolet rays of 300 to 450 nm, and the film is developed using a developer containing benzene, monochlorobenzene or alkylbenzene to remove unexposed parts of the film. How to form a resist pattern.