JPS6113733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation-sensitive composition, and more particularly to a radiation-sensitive composition that prevents a reaction from continuing even after radiation irradiation has stopped.

Conventionally, in optical lithography in which a photosensitive material is used as a photoresist for microfabrication, it is obvious that there is a limit to the machining accuracy on the order of the wavelength of light. In order to perform higher precision processing, electron beam,
Lithography using extremely short wavelength radiation such as X-rays has been proposed. When such radiation-sensitive materials are used as resists, they are called electron beam resists, X-ray resists, etc.

In the early stages of research, photoresists were sometimes used as electron beam resists, but specialized resists with desirable properties for electron beam or X-ray exposure are being developed.

As is well known, there are two types of radiation resists: positive type, in which the molecular chains are cut by radiation and the molecular weight decreases, and negative type, in which crosslinking occurs and the molecular weight increases due to radiation irradiation. be. In general, polymer substances with low molecular weight have high solubility in solvents, so a resist coated on a substrate is irradiated with radiation in a desired pattern, and then immersed in an appropriate solvent. The portion with a relatively low molecular weight is dissolved and removed, and the portion with a relatively high molecular weight remains. Therefore, when a certain figure is irradiated with radiation,
In the resist pattern obtained after development, the irradiated portion remains in the negative type, and the inverted pattern is obtained in the positive type. The sensitivity of a resist is difficult to uniquely determine because it depends on the development method, but the basic question is how many cuts or crosslinks occur in response to a certain amount of radiation irradiation.

When the present inventors attempted precision processing using a negative resist containing repeating units containing epoxy groups, they discovered that the reaction of this material continued even after radiation irradiation was stopped. , published some of the results (11th Semiconductor
Integrated Circuit Technology Symposium Lecture Collection, pages 72-77 (1976)). This fact means that when performing precise drawing on a substrate, if it takes a considerable amount of time to draw by irradiation, there will be a difference in size between the initially drawn part and the final drawn part. . To suppress this undesirable phenomenon,
A composition in which a radical scavenger is added to a negative resist containing repeating units containing epoxy groups,
The present inventors have already proposed this.

The present inventors conducted further research and found that the crosslinking reaction occurs not only in negative resists that occur due to ring opening of epoxy groups, but also in negative resists that crosslink due to carbon-carbon double bonds in the molecule. It was discovered that radicals generated by irradiation do not disappear even after irradiation has stopped, and a chain reaction proceeds, and that this unnecessary reaction after irradiation can be effectively suppressed by adding a reaction inhibitor such as a radical scavenger. We confirmed this and arrived at the present invention, which is extremely meaningful in practice.

That is, in the present invention, unsaturated 2
The object of the present invention is to provide a radiation-sensitive composition comprising a polymer substance containing a unit containing a double bond as an essential requirement and containing a reaction inhibitor to prevent the reaction from continuing even after radiation irradiation has stopped.

According to the present invention, by preventing the reaction from proceeding after the irradiation is stopped, fine processing can be realized without a large error from the intended design value. Furthermore, when performing precise drawing on a substrate, even if it takes a considerable amount of time to draw by irradiation, there is no risk of a difference in size between the initially drawn part and the last drawn part.

The invention will now be explained in detail by way of examples.

Reference Example 1 Drawing was performed by electron beam irradiation on a resist containing 14% by weight of cyclized polybutadiene without adding a reaction inhibitor. First, apply this resist onto a chrome blank using a spinner (6000 rpm), and
℃, prebake for 15 minutes,
A uniform film with a thickness of 0.7 μm was obtained. Using an electron beam exposure device, various patterns with different line widths and line spacings were drawn at an acceleration voltage of 20 KV and a radiation dose of 1 x 10 ^-5 coulombs/cm ² . After repeating drawing under exactly the same conditions on different positions on the same substrate after some time, the chrome blank substrate was taken out from the exposure device and stirred in JRS developer (manufactured by Japan Synthetic Rubber Co., Ltd.) for 60 seconds. It was immersed for development, and then immersed in n-butyl acetate for 30 seconds for rinsing to obtain a resist pattern.

When we closely observed this resist pattern, we found that
Items that have been irradiated for 30 minutes (i.e., items that have been kept in a vacuum exposure device for 30 minutes), 1
The patterns that have been irradiated for 2 hours, 3 hours, 5 hours, and 20 hours have become thicker even though they were irradiated under the same conditions. It has been found that it is inconvenient if it takes more than 30 minutes.

Reference Example 2 An experiment similar to Reference Example 1 was conducted using Osaka Soda Daiso Tap A as a resist. Prepare a solution of 15% by weight of Diosodap A in cyclohexanone and apply it with a spinner (2000 rpm).
A 0.52 μm film was obtained. After drying naturally without hardening, apply an accelerating voltage using an electron beam exposure device.
Drawing was carried out in the same manner as in Reference Example 1 at 20 KV and an irradiation dose of 2.2×10 ⁻⁶ coulombs/cm ² . This was immersed in methyl ethyl ketone for 100 seconds and developed to obtain a resist pattern. This resist pattern also showed an increase in line width over time after irradiation.

Example 1 In the resist containing 14% by weight of cyclized polybutadiene used in Reference Example 1, 5% by weight of cyclized polybutadiene was added.
A composition was prepared by adding and mixing 1,1-diphenyl-2-picrylhydrazyl (DPPH) in an amount of % by weight. When an experiment was conducted in exactly the same manner as described in Reference Example 1, it was found that the irradiation amount was insufficient. In this case, it was necessary to increase it to 1.8×10 ^-6 coulombs/cm ² . By changing only this irradiation condition,
Otherwise, a resist pattern was obtained in exactly the same manner as in Reference Example 1.

When we closely observed this resist pattern, we found that
A pattern with a uniform line width was obtained within a range of up to 20 hours after irradiation.

Example 2 A composition in which 10% by weight of the DPPH used in Example 1 was added to the polymer component of the resist of Reference Example 1,
An experiment was conducted using the method described in Reference Example 1 for a composition in which 2.5% by weight of 2.5% by weight was added. However, the irradiation amount is different from that in Reference Example 1: 3.5×10 ^-6 coulombs/cm ² when 10% by weight is added, and 1.3×10 ^-6 coulombs/cm ² when 2.5% by weight is added. It was necessary to increase each. Even with the addition of 10% DPPH, the adhesion and chemical resistance of the resist were sufficient, and the resulting substrate with a uniform resist pattern was treated with a chrome etching solution (cerium ammonium nitrate with perchloric acid added). A chrome mask could be formed by immersing it in an aqueous solution for 45 seconds. In the case where 2.5% by weight of DPPH was added, the line width of the resist pattern increased, although slightly, as the time elapsed after irradiation.

Example 3 The same effect as in Example 1 was obtained by adding 5% by weight of galvinoxyl to the polymer component of the resist of Reference Example 1.

Example 4 DPPH was added to the resist, which was a 15% solution of Diosodap A used in Reference Example 2, at a ratio of 5% to the polymer component.
Reference Example 2 was applied to a composition in which 5% by weight of galvinoxyl was added and a composition in which 5% by weight of galvinoxyl was added.
The experiment was conducted using the method described above. However, it was necessary to increase the irradiation dose to 4×10 ^-6 coulombs/cm ² . The resist patterns obtained were uniform regardless of the time elapsed after irradiation.

Example 5 A composition in which 10% by weight of iodine was added to the polymeric component of the resist used in Reference Example 1 showed an inhibitory effect on the reaction after irradiation was stopped, but the magnitude of this effect was shown in Example 5. It wasn't even close to 1. However, the required irradiation dose was 1.2×10 ⁻⁶ coulombs/cm ² and did not show a significant increase.

The mechanism of the crosslinking reaction that continues to occur even after irradiation has stopped is largely unknown, but since the diffusion rate of ions in solids is thought to be extremely slow, it is likely that the chain reaction caused by radicals is the main one. It is considered. The experimental facts about post-irradiation effects are already well known in the field of radiation chemistry, and post-polymerization (post-polymerization)
(For example, see "Radiation Polymerization" by Yoneho Tabata (Sangyo Tosho, published in 1962)).

Therefore, the application of the present invention is not limited to the examples given, but is considered to be applicable to all reactions produced by the same reaction mechanism. As examples of polymeric substances, cyclized polybutadiene and polydiallyl orthophthalate (disodap A) were given as examples, but like these two, unsaturated
Resists that cause crosslinking through double bonds, such as polybutadiene, styrene-butadiene copolymers, polymeric substances containing units having acrylic acid groups, methacrylic acid groups, etc. in side chains as polymeric repeating units, and polyvinylsiloxane. All silicone resins containing vinyl groups are expected to have similar effects. Among reaction inhibitors, radical scavengers include tri-p-nitrophenylmethyl, di-p-fluoroaniline, N-(3N-oxyanilino-1,3-
Stable radicals such as (dimethylbutylidene) aniline oxide, substituted products and homologs thereof, alkyl iodides, p-benzoquinone, anthraquinone,
Quinones such as chloranil, polyhydroxy compounds such as hydroquinone, catechol, p-butylcatechol, pyridine, methylaniline, p-phenylenediamine, N-N'-tetraethyl-p
- Amino compounds such as phenylenediamine, m-dinitrobenzene, 2,4-dinitrotoluene,
2,4-dinitrophenol, nitro compounds such as picric acid, nitrosobenzene, nitroso-β-
Nitroso compounds such as naphthol, organic sulfur compounds such as dithiobenzoyl sulfide, p-p'-ditolyltrisulfide, p,p'-ditolyltetrasulfide, ferric chloride, cupric chloride, Metal chlorides such as titanium trichloride and nickel dichloride are known.

Although these reaction inhibitors may have different suppressive effects on the reaction after radiation irradiation has stopped, those with a significant suppressive effect tend to increase the irradiation dose, that is, lower the sensitivity. The user can select the amount or type of additive depending on the required pattern accuracy. It is also known that when two or more types are added in combination, a remarkable synergistic effect appears. Therefore, the reaction inhibitor is not limited to those described in the examples, but all inhibitors of radical reactions and scavengers as inhibitors known in the field of radiation chemistry are included within the scope of the present invention. It is clear that

As mentioned above, by adding a reaction inhibitor to a negative resist containing unsaturated double bonds,
Reactions after irradiation is stopped can be suppressed.

Claims (1)

[Scope of Claims] 1. A polymeric substance containing as an essential condition a unit containing an unsaturated double bond in the polymerization repeating unit contains a reaction inhibitor in an amount of 5% by weight or more and 20% by weight or less based on the polymeric substance. A radiation-sensitive composition comprising: 2. The radiation-sensitive composition according to claim 1, wherein the reaction inhibitor is a radical scavenger. 3. The radiation-sensitive composition according to claim 2, wherein the radical scavenger is a stable radical. 4 Stable radicals include diphenylpicrylhydrazyl, tri-p-nitrophenylmethyl, di-p-
Fluoroaniline, N-(3N-oxyanilino-
4. The radiation-sensitive composition according to claim 3, which is 1,3-dimethylbutylidene)aniline oxide or galbinoxyl, a substituted product thereof, or a homologue thereof. 5. The radiation-sensitive composition according to claim 2, wherein the radical scavenger is iodine or alkyl iodide. 6. The radiation-sensitive composition according to claim 1, wherein the reaction inhibitor is a combination containing two or more types of radical scavengers and the like.