JPS6154246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a resist image, and more particularly to a method for producing a fine resist image using electron beams, X-rays, or deep ultraviolet rays having a wavelength of 3000 Å or less.

Conventionally, photolithography technology, which forms a resist pattern by irradiating light, has been used to manufacture devices that require microscopic processing, such as purple product circuits and bubble memory devices. It is well known that since there is a limit in the wavelength order of light, techniques for forming even finer patterns by irradiation with deep ultraviolet rays, X-rays, electron beams, etc. have been developed and are already being put into practical use.

In the early stages of research, photoresists were sometimes used as the resists used to form patterns by irradiating electron beams, Research and development of materials suitable for deep ultraviolet irradiation is being carried out both in Japan and abroad, and there are already many publications.

As is well known, there are two types of resist: positive type and negative type. Positive type resists become easily soluble in solvents when irradiated, and are dissolved and removed during development processing, resulting in a pattern with unirradiated areas remaining. It is something that can be done. In the negative type, the resist in the irradiated area becomes poorly soluble or insoluble, and a pattern in which the irradiated area remains is obtained by development. In other words, when the same pattern is irradiated, an image of the irradiation pattern or its inverted image can be obtained depending on whether the resist is negative or positive, so both types of resist can be used depending on the purpose. is advantageous.

Many materials have been proposed for positive electron beam resists, including polymethyl methacrylate, polybutene-1-sulfone, and polymethyl isopropenyl ketone.
Many negative-type materials have been proposed, including polyglycidyl methacrylate, copolymers containing glycidyl methacrylate, epoxidized polybutadiene, and polydiallyl phthalate.

In general, positive resists have excellent resolution but are difficult to obtain with high sensitivity, and negative resists, on the other hand, are easy to obtain with high sensitivity but have difficulty in resolution. However, some of the materials mentioned above are already in practical use, and masks have already been manufactured by electron beam lithography. However, in recent years, dry processes have become more
Namely, ion milling, sputter etching,
As techniques such as plasma etching are used to etch resist images onto substrates, resist materials are required to have high resistance to these etching methods, that is, dry etching resistance. I'm getting used to it. Conventionally, resists mainly targeted for mask manufacturing have required sensitivity, resolution, and etching resistance. For example, for chrome mask manufacturing, resistance to ceric ammonium nitrate aqueous solution is required for wet etching of chromium, and dry etching is required. Resistance in the process was not considered.

As a result of research on the dry etching resistance of resist materials, it has been found that the resistance is significantly improved when a conjugated ring such as a phenyl group is included in the molecule. AZ resist (trade name, Shipley Co., Ltd.), which is a photoresist, has good dry etch resistance, but it also contains many phenyl groups. However, the most important polymer containing many phenyl groups is polystyrene, and in fact, polystyrene has the best dry etch resistance among the currently known resists. Moreover, living polymerization can relatively easily produce a nearly monodisperse material, ideally achieving the condition of small molecular weight dispersion, which is essential for improving the performance of negative resists. For this reason, patterning using monodisperse polystyrene as a negative resist has been attempted. The disadvantage is that it is a material with low crosslinking efficiency, so in order to obtain practical sensitivity it is necessary to use a material with an extremely high molecular weight; using polystyrene with a molecular weight of 600,000, the practical sensitivity is approximately 2 × 10 ^-5 Coulomb/cm ² , and in order to obtain a sensitivity of 1×10 ^-5 coulomb/cm ² , a material with a molecular weight of 1 million or more is required. These negative resists, which have increased sensitivity due to higher molecular weight, have relatively fewer crosslinking points, so they are extremely susceptible to swelling in solvents, making it often difficult to manufacture fine resist patterns. . Near-nonpolar solvents having aromatic rings such as benzene and xylene, and chlorinated solvents such as chlorobenzene and dichloroethane, which have been conventionally proposed as developing solutions for polystyrene, are undesirable because they cause severe swelling of high molecular weight polystyrene. Tests showed that a recently proposed mixed solution of methyl ethyl ketone and isopropanol did not have sufficient solubility in polystyrene, and during development, the polystyrene in the portions that were intended to be dissolved became fine particles and peeled off from the substrate surface. It was found that this method was not suitable for practical use because it was impossible to remove any residue.

Under these circumstances, the inventor searched for a solvent that would not significantly swell high-molecular-weight polystyrene and had sufficient solubility, and found that cyclic compounds containing oxygen in the ring, particularly tetrahydrofuran, are suitable as solvents. The present invention was achieved by discovering that.

That is, the present invention applies electron beams to polystyrene.
The present invention provides a method for producing a resist image by irradiating X-rays or deep ultraviolet rays to make the resist insoluble in a solvent, and then dissolving and removing the unirradiated portions using a phenomenon liquid containing, for example, 10 to 100 volume percent of tetrahydrofuran. be. If necessary, after processing with a developer, rinsing treatment may be performed with a solvent having a lower solubility than the developer.

According to the present invention, a fine resist image can be obtained using high molecular weight polystyrene as a negative resist.

The invention will be explained in detail below using examples.

Example 1 5 g of monodisperse polystyrene with a molecular weight of 600,000 and a dispersion of 1.1 or less was dissolved in 95 g of xylene and filtered through a 0.2 μm filter to obtain a resist solution. It was applied by spin coating (3000 revolutions/min 20 seconds) and clinched at 110°C for 30 minutes to obtain a uniform coating film with a thickness of 0.5 microns. Using an electron beam exposure device with an accelerating voltage of 20 KV, latent images were created by drawing patterns of various sizes with an exposure dose of 2.2 x 10 ^-5 coulombs/cm ² , and then developed by immersing them in tetrahydrofuran for 60 seconds. . When the resulting resist pattern was observed, it was found that even a resist pattern with a width of 0.3 microns was completely formed, indicating excellent resolution.

Example 2 The resist solution used in Example 1 was applied by spin coating (1500 revolutions/minute for 20 seconds) and hardened at 110° C. for 30 minutes to obtain a uniform coating film with a thickness of about 0.75 microns. Electron beam exposure was performed in the same manner as in Example 1, followed by immersion in a mixed solution of 3 volumes of tetrahydrofuran and 1 volume of ethanol for 60 seconds for development.
A resist pattern of 0.5 microns or less was also completely formed.

Example 3 The resist solution used in Example 1 was applied by spin coating (1000 rpm, 20 seconds) and hardened at 110° C. for 30 minutes to obtain a uniform coating film with a thickness of about 1 micron. Drawing was performed by electron beam exposure in the same manner as in Example 1, and then developed by immersion in a mixture of 3 volumes of tetrahydrofuran and 1 volume of ethanol for 60 seconds, and then immediately immersed in a mixture of 5 volumes of methyl ethyl ketone and 2 volumes of ethanol. I soaked it for 30 seconds and rinsed it.

When I observed the resulting resist pattern, I found that
The 0.5 micron single wire was also well formed.

In addition, when the resist film is about 1 micron thick, as in Example 1, for comparison, tetrahydrofuran
When the film was immersed for 60 seconds and developed, slight swelling was observed.

As described in detail above, by developing polystyrene using a developer containing tetrahydrofuran, it is possible to produce a negative pattern with excellent resolution with extremely little swelling.

Claims (1)

[Scope of Claims] 1. A method of manufacturing a resist image by irradiating polystyrene with electron beams, X-rays or deep ultraviolet rays to make it insolubilized in a solvent, and then dissolving and removing the unirradiated portions using a developer. 1. A method for producing a resist image, wherein the method is tetrahydrofuran or a solution containing tetrahydrofuran. 2 Tetrahydrofuran contained in the developer is 10~
2. The method for producing a resist image according to claim 1, wherein the resist image is 100% by volume.